package api

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"sort"
	"strconv"
	"strings"

	"github.com/alexedwards/scs/v2"
	"github.com/go-chi/chi/v5"
	"github.com/jackc/pgx/v5/pgconn"
	"github.com/kindredsystems/silo/internal/auth"
	"github.com/kindredsystems/silo/internal/config"
	"github.com/kindredsystems/silo/internal/db"
	"github.com/kindredsystems/silo/internal/partnum"
	"github.com/kindredsystems/silo/internal/schema"
	"github.com/kindredsystems/silo/internal/storage"
	"github.com/rs/zerolog"
	"gopkg.in/yaml.v3"
)

// Server holds dependencies for HTTP handlers.
type Server struct {
	logger        zerolog.Logger
	db            *db.DB
	items         *db.ItemRepository
	projects      *db.ProjectRepository
	relationships *db.RelationshipRepository
	schemas       map[string]*schema.Schema
	schemasDir    string
	partgen       *partnum.Generator
	storage       *storage.Storage
	auth          *auth.Service
	sessions      *scs.SessionManager
	oidc          *auth.OIDCBackend
	authConfig    *config.AuthConfig
	itemFiles     *db.ItemFileRepository
	broker        *Broker
	serverState   *ServerState
}

// NewServer creates a new API server.
func NewServer(
	logger zerolog.Logger,
	database *db.DB,
	schemas map[string]*schema.Schema,
	schemasDir string,
	store *storage.Storage,
	authService *auth.Service,
	sessionManager *scs.SessionManager,
	oidcBackend *auth.OIDCBackend,
	authCfg *config.AuthConfig,
	broker *Broker,
	state *ServerState,
) *Server {
	items := db.NewItemRepository(database)
	projects := db.NewProjectRepository(database)
	relationships := db.NewRelationshipRepository(database)
	itemFiles := db.NewItemFileRepository(database)
	seqStore := &dbSequenceStore{db: database, schemas: schemas}
	partgen := partnum.NewGenerator(schemas, seqStore)

	return &Server{
		logger:        logger,
		db:            database,
		items:         items,
		projects:      projects,
		relationships: relationships,
		schemas:       schemas,
		schemasDir:    schemasDir,
		partgen:       partgen,
		storage:       store,
		auth:          authService,
		sessions:      sessionManager,
		oidc:          oidcBackend,
		authConfig:    authCfg,
		itemFiles:     itemFiles,
		broker:        broker,
		serverState:   state,
	}
}

// dbSequenceStore implements partnum.SequenceStore using the database.
type dbSequenceStore struct {
	db      *db.DB
	schemas map[string]*schema.Schema
}

func (s *dbSequenceStore) NextValue(ctx context.Context, schemaName string, scope string) (int, error) {
	// For now, use schema name as ID. In production, you'd look up the schema UUID.
	return s.db.NextSequenceValue(ctx, schemaName, scope)
}

// Error response structure.
type ErrorResponse struct {
	Error   string `json:"error"`
	Message string `json:"message,omitempty"`
}

// writeJSON writes a JSON response.
func writeJSON(w http.ResponseWriter, status int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(v)
}

// writeError writes an error JSON response.
func writeError(w http.ResponseWriter, status int, err string, message string) {
	writeJSON(w, status, ErrorResponse{Error: err, Message: message})
}

// Health check handlers

// HandleHealth returns basic health status.
func (s *Server) HandleHealth(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, http.StatusOK, map[string]string{
		"status": "ok",
		"mode":   string(s.serverState.Mode()),
	})
}

// HandleReady checks database and storage connectivity.
func (s *Server) HandleReady(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	// Check database
	if err := s.db.Pool().Ping(ctx); err != nil {
		writeError(w, http.StatusServiceUnavailable, "database_unavailable", err.Error())
		return
	}

	storageStatus := "ok"
	if s.storage != nil {
		if err := s.storage.Ping(ctx); err != nil {
			storageStatus = "unavailable"
		}
	} else {
		storageStatus = "not_configured"
	}

	writeJSON(w, http.StatusOK, map[string]any{
		"status":      "ready",
		"database":    "ok",
		"storage":     storageStatus,
		"mode":        string(s.serverState.Mode()),
		"sse_clients": s.broker.ClientCount(),
	})
}

// Schema handlers

// SchemaResponse represents a schema in API responses.
type SchemaResponse struct {
	Name        string            `json:"name"`
	Version     int               `json:"version"`
	Description string            `json:"description"`
	Separator   string            `json:"separator"`
	Format      string            `json:"format"`
	Segments    []SegmentResponse `json:"segments"`
	Examples    []string          `json:"examples,omitempty"`
}

// SegmentResponse represents a schema segment.
type SegmentResponse struct {
	Name        string            `json:"name"`
	Type        string            `json:"type"`
	Description string            `json:"description,omitempty"`
	Required    bool              `json:"required"`
	Values      map[string]string `json:"values,omitempty"`
	Length      int               `json:"length,omitempty"`
}

// HandleListSchemas lists all available schemas.
func (s *Server) HandleListSchemas(w http.ResponseWriter, r *http.Request) {
	schemas := make([]SchemaResponse, 0, len(s.schemas))
	for _, sch := range s.schemas {
		schemas = append(schemas, schemaToResponse(sch))
	}
	writeJSON(w, http.StatusOK, schemas)
}

// HandleGetSchema returns a specific schema.
func (s *Server) HandleGetSchema(w http.ResponseWriter, r *http.Request) {
	name := chi.URLParam(r, "name")
	sch, ok := s.schemas[name]
	if !ok {
		writeError(w, http.StatusNotFound, "not_found", "Schema not found")
		return
	}
	writeJSON(w, http.StatusOK, schemaToResponse(sch))
}

// FormFieldDescriptor describes a single field in the form descriptor response.
type FormFieldDescriptor struct {
	Name        string   `json:"name"`
	Type        string   `json:"type"`
	Widget      string   `json:"widget,omitempty"`
	Label       string   `json:"label"`
	Required    bool     `json:"required,omitempty"`
	Default     any      `json:"default,omitempty"`
	Unit        string   `json:"unit,omitempty"`
	Description string   `json:"description,omitempty"`
	Options     []string `json:"options,omitempty"`
	Currency    string   `json:"currency,omitempty"`

	// Item-field specific
	DerivedFromCategory map[string]string `json:"derived_from_category,omitempty"`
	SearchEndpoint      string            `json:"search_endpoint,omitempty"`
}

// FormFieldGroupDescriptor describes an ordered group of resolved fields.
type FormFieldGroupDescriptor struct {
	Key    string                `json:"key"`
	Label  string                `json:"label"`
	Order  int                   `json:"order"`
	Fields []FormFieldDescriptor `json:"fields"`
}

// HandleGetFormDescriptor returns the full form descriptor for a schema.
func (s *Server) HandleGetFormDescriptor(w http.ResponseWriter, r *http.Request) {
	schemaName := chi.URLParam(r, "name")

	sch, ok := s.schemas[schemaName]
	if !ok {
		writeError(w, http.StatusNotFound, "not_found", "Schema not found")
		return
	}

	result := map[string]any{
		"schema_name": sch.Name,
		"format":      sch.Format,
	}

	// Category picker with auto-derived values_by_domain
	if sch.UI != nil && sch.UI.CategoryPicker != nil {
		picker := map[string]any{
			"style": sch.UI.CategoryPicker.Style,
		}

		vbd := sch.ValuesByDomain()

		stages := make([]map[string]any, 0, len(sch.UI.CategoryPicker.Stages)+1)
		for _, stage := range sch.UI.CategoryPicker.Stages {
			stg := map[string]any{
				"name":  stage.Name,
				"label": stage.Label,
			}
			if stage.Values != nil {
				stg["values"] = stage.Values
			}
			stages = append(stages, stg)
		}

		// Auto-add subcategory stage from values_by_domain
		if vbd != nil {
			stages = append(stages, map[string]any{
				"name":             "subcategory",
				"label":            "Type",
				"values_by_domain": vbd,
			})
		}

		picker["stages"] = stages
		result["category_picker"] = picker
	}

	// Item fields
	if sch.UI != nil && sch.UI.ItemFields != nil {
		result["item_fields"] = sch.UI.ItemFields
	}

	// Resolve field groups into ordered list with full field metadata
	if sch.UI != nil && sch.UI.FieldGroups != nil {
		groups := s.resolveFieldGroups(sch, sch.UI.FieldGroups)
		result["field_groups"] = groups
	}

	// Category field groups
	if sch.UI != nil && sch.UI.CategoryFieldGroups != nil {
		catGroups := make(map[string][]FormFieldGroupDescriptor)
		for prefix, groups := range sch.UI.CategoryFieldGroups {
			catGroups[prefix] = s.resolveCategoryFieldGroups(sch, prefix, groups)
		}
		result["category_field_groups"] = catGroups
	}

	// Field overrides (pass through)
	if sch.UI != nil && sch.UI.FieldOverrides != nil {
		result["field_overrides"] = sch.UI.FieldOverrides
	}

	writeJSON(w, http.StatusOK, result)
}

// resolveFieldGroups converts field group definitions into fully resolved descriptors.
func (s *Server) resolveFieldGroups(sch *schema.Schema, groups map[string]schema.FieldGroup) []FormFieldGroupDescriptor {
	result := make([]FormFieldGroupDescriptor, 0, len(groups))
	for key, group := range groups {
		desc := FormFieldGroupDescriptor{
			Key:   key,
			Label: group.Label,
			Order: group.Order,
		}
		for _, fieldName := range group.Fields {
			fd := s.resolveField(sch, fieldName)
			desc.Fields = append(desc.Fields, fd)
		}
		result = append(result, desc)
	}
	// Sort by order
	sort.Slice(result, func(i, j int) bool {
		return result[i].Order < result[j].Order
	})
	return result
}

// resolveCategoryFieldGroups resolves category-specific field groups.
func (s *Server) resolveCategoryFieldGroups(sch *schema.Schema, prefix string, groups map[string]schema.FieldGroup) []FormFieldGroupDescriptor {
	result := make([]FormFieldGroupDescriptor, 0, len(groups))
	for key, group := range groups {
		desc := FormFieldGroupDescriptor{
			Key:   key,
			Label: group.Label,
			Order: group.Order,
		}
		for _, fieldName := range group.Fields {
			fd := s.resolveCategoryField(sch, prefix, fieldName)
			desc.Fields = append(desc.Fields, fd)
		}
		result = append(result, desc)
	}
	sort.Slice(result, func(i, j int) bool {
		return result[i].Order < result[j].Order
	})
	return result
}

// resolveField builds a FormFieldDescriptor from item_fields or property_schemas.defaults.
func (s *Server) resolveField(sch *schema.Schema, name string) FormFieldDescriptor {
	fd := FormFieldDescriptor{Name: name}

	// Check item_fields first
	if sch.UI != nil && sch.UI.ItemFields != nil {
		if def, ok := sch.UI.ItemFields[name]; ok {
			fd.Type = def.Type
			fd.Widget = def.Widget
			fd.Label = def.Label
			fd.Required = def.Required
			fd.Default = def.Default
			fd.Options = def.Options
			fd.DerivedFromCategory = def.DerivedFromCategory
			fd.SearchEndpoint = def.SearchEndpoint
			s.applyOverrides(sch, name, &fd)
			return fd
		}
	}

	// Check property_schemas.defaults
	if sch.PropertySchemas != nil && sch.PropertySchemas.Defaults != nil {
		if def, ok := sch.PropertySchemas.Defaults[name]; ok {
			fd.Type = def.Type
			fd.Label = name // Use field name as label if not overridden
			fd.Default = def.Default
			fd.Unit = def.Unit
			fd.Description = def.Description
			fd.Required = def.Required
			s.applyOverrides(sch, name, &fd)
			return fd
		}
	}

	// Fallback — field name only
	fd.Label = name
	fd.Type = "string"
	s.applyOverrides(sch, name, &fd)
	return fd
}

// resolveCategoryField builds a FormFieldDescriptor from category-specific property schema.
func (s *Server) resolveCategoryField(sch *schema.Schema, prefix, name string) FormFieldDescriptor {
	fd := FormFieldDescriptor{Name: name, Label: name, Type: "string"}

	if sch.PropertySchemas != nil {
		if catProps, ok := sch.PropertySchemas.Categories[prefix]; ok {
			if def, ok := catProps[name]; ok {
				fd.Type = def.Type
				fd.Default = def.Default
				fd.Unit = def.Unit
				fd.Description = def.Description
				fd.Required = def.Required
			}
		}
	}

	s.applyOverrides(sch, name, &fd)
	return fd
}

// applyOverrides applies field_overrides to a field descriptor.
func (s *Server) applyOverrides(sch *schema.Schema, name string, fd *FormFieldDescriptor) {
	if sch.UI == nil || sch.UI.FieldOverrides == nil {
		return
	}
	ov, ok := sch.UI.FieldOverrides[name]
	if !ok {
		return
	}
	if ov.Widget != "" {
		fd.Widget = ov.Widget
	}
	if ov.Currency != "" {
		fd.Currency = ov.Currency
	}
	if len(ov.Options) > 0 {
		fd.Options = ov.Options
	}
}

func schemaToResponse(sch *schema.Schema) SchemaResponse {
	segments := make([]SegmentResponse, len(sch.Segments))
	for i, seg := range sch.Segments {
		segments[i] = SegmentResponse{
			Name:        seg.Name,
			Type:        seg.Type,
			Description: seg.Description,
			Required:    seg.Required,
			Values:      seg.Values,
			Length:      seg.Length,
		}
	}
	return SchemaResponse{
		Name:        sch.Name,
		Version:     sch.Version,
		Description: sch.Description,
		Separator:   sch.Separator,
		Format:      sch.Format,
		Segments:    segments,
		Examples:    sch.Examples,
	}
}

// Item handlers

// ItemResponse represents an item in API responses.
type ItemResponse struct {
	ID              string         `json:"id"`
	PartNumber      string         `json:"part_number"`
	ItemType        string         `json:"item_type"`
	Description     string         `json:"description"`
	CurrentRevision int            `json:"current_revision"`
	CreatedAt       string         `json:"created_at"`
	UpdatedAt       string         `json:"updated_at"`
	SourcingType    string         `json:"sourcing_type"`
	LongDescription *string        `json:"long_description,omitempty"`
	ThumbnailKey    *string        `json:"thumbnail_key,omitempty"`
	FileCount       int            `json:"file_count"`
	FilesTotalSize  int64          `json:"files_total_size"`
	Properties      map[string]any `json:"properties,omitempty"`
}

// CreateItemRequest represents a request to create an item.
type CreateItemRequest struct {
	Schema          string         `json:"schema"`
	Category        string         `json:"category"`
	Description     string         `json:"description"`
	Projects        []string       `json:"projects,omitempty"`
	Properties      map[string]any `json:"properties,omitempty"`
	SourcingType    string         `json:"sourcing_type,omitempty"`
	LongDescription *string        `json:"long_description,omitempty"`
}

// HandleListItems lists items with optional filtering.
func (s *Server) HandleListItems(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	opts := db.ListOptions{
		ItemType: r.URL.Query().Get("type"),
		Search:   r.URL.Query().Get("search"),
		Project:  r.URL.Query().Get("project"),
	}

	if limit := r.URL.Query().Get("limit"); limit != "" {
		if l, err := strconv.Atoi(limit); err == nil {
			opts.Limit = l
		}
	}
	if offset := r.URL.Query().Get("offset"); offset != "" {
		if o, err := strconv.Atoi(offset); err == nil {
			opts.Offset = o
		}
	}

	items, err := s.items.List(ctx, opts)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to list items")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to list items")
		return
	}

	// Batch-fetch file attachment stats
	ids := make([]string, len(items))
	for i, item := range items {
		ids[i] = item.ID
	}
	fileStats, _ := s.items.BatchGetFileStats(ctx, ids)

	response := make([]ItemResponse, len(items))
	for i, item := range items {
		response[i] = itemToResponse(item)
		if fs, ok := fileStats[item.ID]; ok {
			response[i].FileCount = fs.Count
			response[i].FilesTotalSize = fs.TotalSize
		}
	}

	writeJSON(w, http.StatusOK, response)
}

// HandleFuzzySearch performs fuzzy search across items.
func (s *Server) HandleFuzzySearch(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	q := r.URL.Query().Get("q")
	if q == "" {
		writeJSON(w, http.StatusOK, []FuzzyResult{})
		return
	}

	fieldsParam := r.URL.Query().Get("fields")
	var fields []string
	if fieldsParam != "" {
		fields = strings.Split(fieldsParam, ",")
	}

	limit := 50
	if l := r.URL.Query().Get("limit"); l != "" {
		if parsed, err := strconv.Atoi(l); err == nil && parsed > 0 {
			limit = parsed
		}
	}

	// Pre-filter by type and project via SQL (no search term)
	opts := db.ListOptions{
		ItemType: r.URL.Query().Get("type"),
		Project:  r.URL.Query().Get("project"),
		Limit:    500, // reasonable upper bound for fuzzy matching
	}

	items, err := s.items.List(ctx, opts)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to list items for fuzzy search")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to search items")
		return
	}

	responses := make([]ItemResponse, len(items))
	for i, item := range items {
		responses[i] = itemToResponse(item)
	}

	results := FuzzySearch(q, responses, fields, limit)
	writeJSON(w, http.StatusOK, results)
}

// HandleCreateItem creates a new item with generated part number.
func (s *Server) HandleCreateItem(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	var req CreateItemRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_json", err.Error())
		return
	}

	// Default schema
	schemaName := req.Schema
	if schemaName == "" {
		schemaName = "kindred-rd"
	}

	// Generate part number (no longer includes project)
	input := partnum.Input{
		SchemaName: schemaName,
		Values: map[string]string{
			"category": req.Category,
		},
	}

	// Determine item type from category
	itemType := "part"
	if len(req.Category) > 0 {
		switch req.Category[0] {
		case 'A':
			itemType = "assembly"
		case 'T':
			itemType = "tooling"
		}
	}

	properties := req.Properties
	if properties == nil {
		properties = make(map[string]any)
	}
	properties["category"] = req.Category

	// Retry loop: if the generated part number collides with an existing
	// item (sequence counter out of sync), generate a new one and retry.
	const maxRetries = 5
	var item *db.Item
	for attempt := 0; attempt < maxRetries; attempt++ {
		partNumber, err := s.partgen.Generate(ctx, input)
		if err != nil {
			s.logger.Error().Err(err).Msg("failed to generate part number")
			writeError(w, http.StatusBadRequest, "generation_failed", err.Error())
			return
		}

		item = &db.Item{
			PartNumber:      partNumber,
			ItemType:        itemType,
			Description:     req.Description,
			SourcingType:    req.SourcingType,
			LongDescription: req.LongDescription,
		}
		if user := auth.UserFromContext(ctx); user != nil {
			item.CreatedBy = &user.Username
		}

		err = s.items.Create(ctx, item, properties)
		if err == nil {
			break // success
		}

		// Check if this is a duplicate key error — retry with next sequence
		var pgErr *pgconn.PgError
		if errors.As(err, &pgErr) && pgErr.Code == "23505" {
			s.logger.Warn().
				Str("part_number", partNumber).
				Int("attempt", attempt+1).
				Msg("duplicate part number, retrying with next sequence value")
			continue
		}

		// Non-duplicate error, fail immediately
		s.logger.Error().Err(err).Msg("failed to create item")
		writeError(w, http.StatusInternalServerError, "create_failed", err.Error())
		return
	}

	if item == nil || item.ID == "" {
		s.logger.Error().Int("retries", maxRetries).Msg("exhausted retries for part number generation")
		writeError(w, http.StatusConflict, "duplicate_part_number", "Could not generate a unique part number after multiple attempts")
		return
	}

	// Tag item with projects if provided
	if len(req.Projects) > 0 {
		for _, projectCode := range req.Projects {
			if err := s.projects.AddItemToProjectByCode(ctx, item.ID, projectCode); err != nil {
				s.logger.Warn().Err(err).Str("project", projectCode).Msg("failed to tag item with project")
			}
		}
	}

	resp := itemToResponse(item)
	writeJSON(w, http.StatusCreated, resp)
	s.broker.Publish("item.created", mustMarshal(resp))
}

// HandleGetItemByUUID retrieves an item by its stable UUID (the items.id column).
// Used by silo-mod to resolve FreeCAD document SiloUUID properties to part numbers.
func (s *Server) HandleGetItemByUUID(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	uuid := chi.URLParam(r, "uuid")

	item, err := s.items.GetByID(ctx, uuid)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get item by UUID")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get item")
		return
	}
	if item == nil || item.ArchivedAt != nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	response := itemToResponse(item)
	if fileStats, err := s.items.BatchGetFileStats(ctx, []string{item.ID}); err == nil {
		if fs, ok := fileStats[item.ID]; ok {
			response.FileCount = fs.Count
			response.FilesTotalSize = fs.TotalSize
		}
	}

	writeJSON(w, http.StatusOK, response)
}

// HandleGetItem retrieves an item by part number.
// Supports query param: ?include=properties to include current revision properties.
func (s *Server) HandleGetItem(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get item")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get item")
		return
	}
	if item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	response := itemToResponse(item)

	// File attachment stats
	if fileStats, err := s.items.BatchGetFileStats(ctx, []string{item.ID}); err == nil {
		if fs, ok := fileStats[item.ID]; ok {
			response.FileCount = fs.Count
			response.FilesTotalSize = fs.TotalSize
		}
	}

	// Include properties from current revision if requested
	if r.URL.Query().Get("include") == "properties" {
		revisions, err := s.items.GetRevisions(ctx, item.ID)
		if err == nil {
			for _, rev := range revisions {
				if rev.RevisionNumber == item.CurrentRevision {
					response.Properties = rev.Properties
					break
				}
			}
		}
	}

	writeJSON(w, http.StatusOK, response)
}

// UpdateItemRequest represents a request to update an item.
type UpdateItemRequest struct {
	PartNumber      string         `json:"part_number,omitempty"`
	ItemType        string         `json:"item_type,omitempty"`
	Description     string         `json:"description,omitempty"`
	Properties      map[string]any `json:"properties,omitempty"`
	Comment         string         `json:"comment,omitempty"`
	SourcingType    *string        `json:"sourcing_type,omitempty"`
	LongDescription *string        `json:"long_description,omitempty"`
}

// HandleUpdateItem updates an item's fields and/or creates a new revision.
func (s *Server) HandleUpdateItem(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get item")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get item")
		return
	}
	if item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	var req UpdateItemRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_json", err.Error())
		return
	}

	// Update item fields if provided
	fields := db.UpdateItemFields{
		PartNumber:      item.PartNumber,
		ItemType:        item.ItemType,
		Description:     item.Description,
		SourcingType:    req.SourcingType,
		LongDescription: req.LongDescription,
	}

	if req.PartNumber != "" {
		fields.PartNumber = req.PartNumber
	}
	if req.ItemType != "" {
		fields.ItemType = req.ItemType
	}
	if req.Description != "" {
		fields.Description = req.Description
	}

	// Update the item record (UUID stays the same)
	if user := auth.UserFromContext(ctx); user != nil {
		fields.UpdatedBy = &user.Username
	}
	if err := s.items.Update(ctx, item.ID, fields); err != nil {
		s.logger.Error().Err(err).Msg("failed to update item")
		writeError(w, http.StatusInternalServerError, "update_failed", err.Error())
		return
	}

	// Create new revision if properties provided
	if req.Properties != nil {
		rev := &db.Revision{
			ItemID:     item.ID,
			Properties: req.Properties,
			Comment:    &req.Comment,
		}
		if user := auth.UserFromContext(ctx); user != nil {
			rev.CreatedBy = &user.Username
		}

		if err := s.items.CreateRevision(ctx, rev); err != nil {
			s.logger.Error().Err(err).Msg("failed to create revision")
			writeError(w, http.StatusInternalServerError, "revision_failed", err.Error())
			return
		}
	}

	// Get updated item (use new part number if changed)
	item, _ = s.items.GetByPartNumber(ctx, fields.PartNumber)
	resp := itemToResponse(item)
	writeJSON(w, http.StatusOK, resp)
	s.broker.Publish("item.updated", mustMarshal(resp))
}

// HandleDeleteItem permanently deletes an item.
// Use query param ?soft=true for soft delete (archive).
func (s *Server) HandleDeleteItem(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")
	soft := r.URL.Query().Get("soft") == "true"

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get item")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get item")
		return
	}
	if item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	if soft {
		if err := s.items.Archive(ctx, item.ID); err != nil {
			s.logger.Error().Err(err).Msg("failed to archive item")
			writeError(w, http.StatusInternalServerError, "archive_failed", err.Error())
			return
		}
	} else {
		if err := s.items.Delete(ctx, item.ID); err != nil {
			s.logger.Error().Err(err).Msg("failed to delete item")
			writeError(w, http.StatusInternalServerError, "delete_failed", err.Error())
			return
		}
	}

	w.WriteHeader(http.StatusNoContent)
	s.broker.Publish("item.deleted", mustMarshal(map[string]string{"part_number": partNumber}))
}

// Revision handlers

// RevisionResponse represents a revision in API responses.
type RevisionResponse struct {
	ID             string         `json:"id"`
	RevisionNumber int            `json:"revision_number"`
	Properties     map[string]any `json:"properties"`
	FileKey        *string        `json:"file_key,omitempty"`
	FileChecksum   *string        `json:"file_checksum,omitempty"`
	FileSize       *int64         `json:"file_size,omitempty"`
	CreatedAt      string         `json:"created_at"`
	CreatedBy      *string        `json:"created_by,omitempty"`
	Comment        *string        `json:"comment,omitempty"`
	Status         string         `json:"status"`
	Labels         []string       `json:"labels"`
}

// RevisionDiffResponse represents the API response for revision comparison.
type RevisionDiffResponse struct {
	FromRevision int                          `json:"from_revision"`
	ToRevision   int                          `json:"to_revision"`
	FromStatus   string                       `json:"from_status"`
	ToStatus     string                       `json:"to_status"`
	FileChanged  bool                         `json:"file_changed"`
	FileSizeDiff *int64                       `json:"file_size_diff,omitempty"`
	Added        map[string]any               `json:"added,omitempty"`
	Removed      map[string]any               `json:"removed,omitempty"`
	Changed      map[string]db.PropertyChange `json:"changed,omitempty"`
}

// UpdateRevisionRequest represents a request to update revision status/labels.
type UpdateRevisionRequest struct {
	Status *string  `json:"status,omitempty"`
	Labels []string `json:"labels,omitempty"`
}

// RollbackRequest represents a request to rollback to a previous revision.
type RollbackRequest struct {
	Comment string `json:"comment,omitempty"`
}

// HandleListRevisions lists revisions for an item.
func (s *Server) HandleListRevisions(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get item")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get item")
		return
	}
	if item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	revisions, err := s.items.GetRevisions(ctx, item.ID)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get revisions")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get revisions")
		return
	}

	response := make([]RevisionResponse, len(revisions))
	for i, rev := range revisions {
		response[i] = revisionToResponse(rev)
	}

	writeJSON(w, http.StatusOK, response)
}

// HandleGetRevision retrieves a specific revision.
func (s *Server) HandleGetRevision(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")
	revStr := chi.URLParam(r, "revision")

	revNum, err := strconv.Atoi(revStr)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid_revision", "Revision must be a number")
		return
	}

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil || item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	revisions, err := s.items.GetRevisions(ctx, item.ID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get revisions")
		return
	}

	for _, rev := range revisions {
		if rev.RevisionNumber == revNum {
			writeJSON(w, http.StatusOK, revisionToResponse(rev))
			return
		}
	}

	writeError(w, http.StatusNotFound, "not_found", "Revision not found")
}

// HandleUpdateRevision updates the status and/or labels of a revision.
func (s *Server) HandleUpdateRevision(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")
	revStr := chi.URLParam(r, "revision")

	revNum, err := strconv.Atoi(revStr)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid_revision", "Revision must be a number")
		return
	}

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get item")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get item")
		return
	}
	if item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	var req UpdateRevisionRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_json", err.Error())
		return
	}

	// Validate that at least one field is being updated
	if req.Status == nil && req.Labels == nil {
		writeError(w, http.StatusBadRequest, "invalid_request", "Must provide status or labels to update")
		return
	}

	err = s.items.UpdateRevisionStatus(ctx, item.ID, revNum, req.Status, req.Labels)
	if err != nil {
		if err.Error() == "revision not found" {
			writeError(w, http.StatusNotFound, "not_found", "Revision not found")
			return
		}
		s.logger.Error().Err(err).Msg("failed to update revision")
		writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
		return
	}

	// Return updated revision
	rev, err := s.items.GetRevision(ctx, item.ID, revNum)
	if err != nil || rev == nil {
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get updated revision")
		return
	}

	writeJSON(w, http.StatusOK, revisionToResponse(rev))
}

// HandleCompareRevisions compares two revisions and returns their differences.
func (s *Server) HandleCompareRevisions(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")

	// Get query parameters for from and to revisions
	fromStr := r.URL.Query().Get("from")
	toStr := r.URL.Query().Get("to")

	if fromStr == "" || toStr == "" {
		writeError(w, http.StatusBadRequest, "invalid_request", "Must provide 'from' and 'to' query parameters")
		return
	}

	fromRev, err := strconv.Atoi(fromStr)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid_revision", "'from' must be a number")
		return
	}

	toRev, err := strconv.Atoi(toStr)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid_revision", "'to' must be a number")
		return
	}

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get item")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get item")
		return
	}
	if item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	diff, err := s.items.CompareRevisions(ctx, item.ID, fromRev, toRev)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to compare revisions")
		writeError(w, http.StatusBadRequest, "comparison_failed", err.Error())
		return
	}

	response := RevisionDiffResponse{
		FromRevision: diff.FromRevision,
		ToRevision:   diff.ToRevision,
		FromStatus:   diff.FromStatus,
		ToStatus:     diff.ToStatus,
		FileChanged:  diff.FileChanged,
		FileSizeDiff: diff.FileSizeDiff,
		Added:        diff.Added,
		Removed:      diff.Removed,
		Changed:      diff.Changed,
	}

	writeJSON(w, http.StatusOK, response)
}

// HandleRollbackRevision creates a new revision by copying from an existing one.
func (s *Server) HandleRollbackRevision(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")
	revStr := chi.URLParam(r, "revision")

	revNum, err := strconv.Atoi(revStr)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid_revision", "Revision must be a number")
		return
	}

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get item")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get item")
		return
	}
	if item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	var req RollbackRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil && err.Error() != "EOF" {
		writeError(w, http.StatusBadRequest, "invalid_json", err.Error())
		return
	}

	// Generate comment if not provided
	comment := req.Comment
	if comment == "" {
		comment = fmt.Sprintf("Rollback to revision %d", revNum)
	}

	var createdBy *string
	if user := auth.UserFromContext(ctx); user != nil {
		createdBy = &user.Username
	}
	newRev, err := s.items.CreateRevisionFromExisting(ctx, item.ID, revNum, comment, createdBy)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to create rollback revision")
		writeError(w, http.StatusBadRequest, "rollback_failed", err.Error())
		return
	}

	s.logger.Info().
		Str("part_number", partNumber).
		Int("source_revision", revNum).
		Int("new_revision", newRev.RevisionNumber).
		Msg("rollback revision created")

	writeJSON(w, http.StatusCreated, revisionToResponse(newRev))
	s.broker.Publish("revision.created", mustMarshal(map[string]any{
		"part_number":     partNumber,
		"revision_number": newRev.RevisionNumber,
		"rollback_from":   revNum,
	}))
}

// Part number generation

// GeneratePartNumberRequest represents a request to generate a part number.
type GeneratePartNumberRequest struct {
	Schema   string `json:"schema"`
	Project  string `json:"project"`
	Category string `json:"category"`
}

// HandleGeneratePartNumber generates a part number without creating an item.
func (s *Server) HandleGeneratePartNumber(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	var req GeneratePartNumberRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_json", err.Error())
		return
	}

	schemaName := req.Schema
	if schemaName == "" {
		schemaName = "kindred-rd"
	}

	input := partnum.Input{
		SchemaName: schemaName,
		Values: map[string]string{
			"project":  req.Project,
			"category": req.Category,
		},
	}

	partNumber, err := s.partgen.Generate(ctx, input)
	if err != nil {
		writeError(w, http.StatusBadRequest, "generation_failed", err.Error())
		return
	}

	writeJSON(w, http.StatusOK, map[string]string{"part_number": partNumber})
}

// Schema value management handlers

// AddSchemaValueRequest represents a request to add a new enum value.
type AddSchemaValueRequest struct {
	Code        string `json:"code"`
	Description string `json:"description"`
}

// UpdateSchemaValueRequest represents a request to update an enum value description.
type UpdateSchemaValueRequest struct {
	Description string `json:"description"`
}

// HandleAddSchemaValue adds a new value to an enum segment.
func (s *Server) HandleAddSchemaValue(w http.ResponseWriter, r *http.Request) {
	schemaName := chi.URLParam(r, "name")
	segmentName := chi.URLParam(r, "segment")

	sch, ok := s.schemas[schemaName]
	if !ok {
		writeError(w, http.StatusNotFound, "not_found", "Schema not found")
		return
	}

	// Find the segment
	var segment *schema.Segment
	for i := range sch.Segments {
		if sch.Segments[i].Name == segmentName {
			segment = &sch.Segments[i]
			break
		}
	}
	if segment == nil {
		writeError(w, http.StatusNotFound, "not_found", "Segment not found")
		return
	}
	if segment.Type != "enum" {
		writeError(w, http.StatusBadRequest, "invalid_segment", "Segment is not an enum type")
		return
	}

	var req AddSchemaValueRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_json", err.Error())
		return
	}

	if req.Code == "" || req.Description == "" {
		writeError(w, http.StatusBadRequest, "invalid_request", "Code and description are required")
		return
	}

	// Check if code already exists
	if _, exists := segment.Values[req.Code]; exists {
		writeError(w, http.StatusConflict, "already_exists", "Value code already exists")
		return
	}

	// Add the new value
	segment.Values[req.Code] = req.Description

	// Save to file
	if err := s.saveSchema(sch); err != nil {
		s.logger.Error().Err(err).Msg("failed to save schema")
		writeError(w, http.StatusInternalServerError, "save_failed", err.Error())
		return
	}

	writeJSON(w, http.StatusCreated, map[string]string{"code": req.Code, "description": req.Description})
}

// HandleUpdateSchemaValue updates an enum value's description.
func (s *Server) HandleUpdateSchemaValue(w http.ResponseWriter, r *http.Request) {
	schemaName := chi.URLParam(r, "name")
	segmentName := chi.URLParam(r, "segment")
	code := chi.URLParam(r, "code")

	sch, ok := s.schemas[schemaName]
	if !ok {
		writeError(w, http.StatusNotFound, "not_found", "Schema not found")
		return
	}

	// Find the segment
	var segment *schema.Segment
	for i := range sch.Segments {
		if sch.Segments[i].Name == segmentName {
			segment = &sch.Segments[i]
			break
		}
	}
	if segment == nil {
		writeError(w, http.StatusNotFound, "not_found", "Segment not found")
		return
	}
	if segment.Type != "enum" {
		writeError(w, http.StatusBadRequest, "invalid_segment", "Segment is not an enum type")
		return
	}

	// Check if code exists
	if _, exists := segment.Values[code]; !exists {
		writeError(w, http.StatusNotFound, "not_found", "Value code not found")
		return
	}

	var req UpdateSchemaValueRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_json", err.Error())
		return
	}

	if req.Description == "" {
		writeError(w, http.StatusBadRequest, "invalid_request", "Description is required")
		return
	}

	// Update the value
	segment.Values[code] = req.Description

	// Save to file
	if err := s.saveSchema(sch); err != nil {
		s.logger.Error().Err(err).Msg("failed to save schema")
		writeError(w, http.StatusInternalServerError, "save_failed", err.Error())
		return
	}

	writeJSON(w, http.StatusOK, map[string]string{"code": code, "description": req.Description})
}

// HandleDeleteSchemaValue removes an enum value.
func (s *Server) HandleDeleteSchemaValue(w http.ResponseWriter, r *http.Request) {
	schemaName := chi.URLParam(r, "name")
	segmentName := chi.URLParam(r, "segment")
	code := chi.URLParam(r, "code")

	sch, ok := s.schemas[schemaName]
	if !ok {
		writeError(w, http.StatusNotFound, "not_found", "Schema not found")
		return
	}

	// Find the segment
	var segment *schema.Segment
	for i := range sch.Segments {
		if sch.Segments[i].Name == segmentName {
			segment = &sch.Segments[i]
			break
		}
	}
	if segment == nil {
		writeError(w, http.StatusNotFound, "not_found", "Segment not found")
		return
	}
	if segment.Type != "enum" {
		writeError(w, http.StatusBadRequest, "invalid_segment", "Segment is not an enum type")
		return
	}

	// Check if code exists
	if _, exists := segment.Values[code]; !exists {
		writeError(w, http.StatusNotFound, "not_found", "Value code not found")
		return
	}

	// Delete the value
	delete(segment.Values, code)

	// Save to file
	if err := s.saveSchema(sch); err != nil {
		s.logger.Error().Err(err).Msg("failed to save schema")
		writeError(w, http.StatusInternalServerError, "save_failed", err.Error())
		return
	}

	w.WriteHeader(http.StatusNoContent)
}

// saveSchema writes the schema back to its YAML file.
func (s *Server) saveSchema(sch *schema.Schema) error {
	// Build the schema file structure
	schemaFile := schema.SchemaFile{
		Schema: *sch,
	}

	data, err := yaml.Marshal(schemaFile)
	if err != nil {
		return err
	}

	filename := filepath.Join(s.schemasDir, sch.Name+".yaml")
	return os.WriteFile(filename, data, 0644)
}

// Helper functions

func itemToResponse(item *db.Item) ItemResponse {
	return ItemResponse{
		ID:              item.ID,
		PartNumber:      item.PartNumber,
		ItemType:        item.ItemType,
		Description:     item.Description,
		CurrentRevision: item.CurrentRevision,
		CreatedAt:       item.CreatedAt.Format("2006-01-02T15:04:05Z07:00"),
		UpdatedAt:       item.UpdatedAt.Format("2006-01-02T15:04:05Z07:00"),
		SourcingType:    item.SourcingType,
		LongDescription: item.LongDescription,
		ThumbnailKey:    item.ThumbnailKey,
	}
}

func revisionToResponse(rev *db.Revision) RevisionResponse {
	labels := rev.Labels
	if labels == nil {
		labels = []string{}
	}
	return RevisionResponse{
		ID:             rev.ID,
		RevisionNumber: rev.RevisionNumber,
		Properties:     rev.Properties,
		FileKey:        rev.FileKey,
		FileChecksum:   rev.FileChecksum,
		FileSize:       rev.FileSize,
		CreatedAt:      rev.CreatedAt.Format("2006-01-02T15:04:05Z07:00"),
		CreatedBy:      rev.CreatedBy,
		Comment:        rev.Comment,
		Status:         rev.Status,
		Labels:         labels,
	}
}

// File upload/download handlers

// CreateRevisionRequest represents a request to create a new revision.
type CreateRevisionRequest struct {
	Properties map[string]any `json:"properties"`
	Comment    string         `json:"comment"`
}

// HandleCreateRevision creates a new revision for an item (without file).
func (s *Server) HandleCreateRevision(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get item")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get item")
		return
	}
	if item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	var req CreateRevisionRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_json", err.Error())
		return
	}

	rev := &db.Revision{
		ItemID:     item.ID,
		Properties: req.Properties,
		Comment:    &req.Comment,
	}
	if user := auth.UserFromContext(ctx); user != nil {
		rev.CreatedBy = &user.Username
	}

	if err := s.items.CreateRevision(ctx, rev); err != nil {
		s.logger.Error().Err(err).Msg("failed to create revision")
		writeError(w, http.StatusInternalServerError, "revision_failed", err.Error())
		return
	}

	writeJSON(w, http.StatusCreated, revisionToResponse(rev))
	s.broker.Publish("revision.created", mustMarshal(map[string]any{
		"part_number":     partNumber,
		"revision_number": rev.RevisionNumber,
	}))
}

// HandleUploadFile uploads a file and creates a new revision.
func (s *Server) HandleUploadFile(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")

	// Check storage is configured
	if s.storage == nil {
		writeError(w, http.StatusServiceUnavailable, "storage_unavailable", "File storage not configured")
		return
	}

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get item")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get item")
		return
	}
	if item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	// Parse multipart form (max 100MB)
	if err := r.ParseMultipartForm(100 << 20); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_form", err.Error())
		return
	}

	// Get the file
	file, header, err := r.FormFile("file")
	if err != nil {
		writeError(w, http.StatusBadRequest, "missing_file", "File is required")
		return
	}
	defer file.Close()

	// Get optional fields
	comment := r.FormValue("comment")
	propertiesJSON := r.FormValue("properties")

	var properties map[string]any
	if propertiesJSON != "" {
		if err := json.Unmarshal([]byte(propertiesJSON), &properties); err != nil {
			writeError(w, http.StatusBadRequest, "invalid_properties", "Properties must be valid JSON")
			return
		}
	} else {
		properties = make(map[string]any)
	}

	// Determine the next revision number
	nextRevision := item.CurrentRevision + 1

	// Generate storage key
	fileKey := storage.FileKey(partNumber, nextRevision)

	// Determine content type
	contentType := header.Header.Get("Content-Type")
	if contentType == "" {
		contentType = "application/octet-stream"
	}

	// Upload to storage
	result, err := s.storage.Put(ctx, fileKey, file, header.Size, contentType)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to upload file")
		writeError(w, http.StatusInternalServerError, "upload_failed", err.Error())
		return
	}

	// Create revision with file metadata
	rev := &db.Revision{
		ItemID:       item.ID,
		Properties:   properties,
		FileKey:      &result.Key,
		FileVersion:  &result.VersionID,
		FileChecksum: &result.Checksum,
		FileSize:     &result.Size,
		Comment:      &comment,
	}
	if user := auth.UserFromContext(ctx); user != nil {
		rev.CreatedBy = &user.Username
	}

	if err := s.items.CreateRevision(ctx, rev); err != nil {
		s.logger.Error().Err(err).Msg("failed to create revision")
		writeError(w, http.StatusInternalServerError, "revision_failed", err.Error())
		return
	}

	s.logger.Info().
		Str("part_number", partNumber).
		Int("revision", rev.RevisionNumber).
		Str("file_key", fileKey).
		Int64("size", result.Size).
		Msg("file uploaded")

	writeJSON(w, http.StatusCreated, revisionToResponse(rev))
}

// HandleDownloadFile downloads the file for a specific revision.
func (s *Server) HandleDownloadFile(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")
	revStr := chi.URLParam(r, "revision")

	// Check storage is configured
	if s.storage == nil {
		writeError(w, http.StatusServiceUnavailable, "storage_unavailable", "File storage not configured")
		return
	}

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil || item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	// Parse revision number (or use "latest")
	var revNum int
	if revStr == "latest" {
		revNum = item.CurrentRevision
	} else {
		revNum, err = strconv.Atoi(revStr)
		if err != nil {
			writeError(w, http.StatusBadRequest, "invalid_revision", "Revision must be a number or 'latest'")
			return
		}
	}

	// Get revision to find file key
	revisions, err := s.items.GetRevisions(ctx, item.ID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get revisions")
		return
	}

	var revision *db.Revision
	for _, rev := range revisions {
		if rev.RevisionNumber == revNum {
			revision = rev
			break
		}
	}

	if revision == nil {
		writeError(w, http.StatusNotFound, "not_found", "Revision not found")
		return
	}

	if revision.FileKey == nil {
		writeError(w, http.StatusNotFound, "no_file", "Revision has no associated file")
		return
	}

	// Get file from storage
	var reader interface {
		Read(p []byte) (n int, err error)
		Close() error
	}

	if revision.FileVersion != nil && *revision.FileVersion != "" {
		reader, err = s.storage.GetVersion(ctx, *revision.FileKey, *revision.FileVersion)
	} else {
		reader, err = s.storage.Get(ctx, *revision.FileKey)
	}

	if err != nil {
		s.logger.Error().Err(err).Str("key", *revision.FileKey).Msg("failed to get file")
		writeError(w, http.StatusInternalServerError, "download_failed", err.Error())
		return
	}
	defer reader.Close()

	// Set response headers
	filename := partNumber + "_rev" + strconv.Itoa(revNum) + ".FCStd"
	w.Header().Set("Content-Type", "application/octet-stream")
	w.Header().Set("Content-Disposition", "attachment; filename=\""+filename+"\"")
	if revision.FileSize != nil {
		w.Header().Set("Content-Length", strconv.FormatInt(*revision.FileSize, 10))
	}

	// Stream file to response
	buf := make([]byte, 32*1024)
	for {
		n, readErr := reader.Read(buf)
		if n > 0 {
			if _, writeErr := w.Write(buf[:n]); writeErr != nil {
				s.logger.Error().Err(writeErr).Msg("failed to write response")
				return
			}
		}
		if readErr != nil {
			break
		}
	}
}

// HandleDownloadLatestFile downloads the file for the latest revision.
func (s *Server) HandleDownloadLatestFile(w http.ResponseWriter, r *http.Request) {
	chi.URLParam(r, "partNumber") // ensure URL param is consumed
	r = r.WithContext(context.WithValue(r.Context(), chi.RouteCtxKey, chi.RouteContext(r.Context())))

	// Add "latest" as the revision param and delegate
	rctx := chi.RouteContext(r.Context())
	rctx.URLParams.Add("revision", "latest")
	s.HandleDownloadFile(w, r)
}

// Project handlers

// ProjectResponse represents a project in API responses.
type ProjectResponse struct {
	ID          string `json:"id"`
	Code        string `json:"code"`
	Name        string `json:"name,omitempty"`
	Description string `json:"description,omitempty"`
	CreatedAt   string `json:"created_at"`
}

// CreateProjectRequest represents a request to create a project.
type CreateProjectRequest struct {
	Code        string `json:"code"`
	Name        string `json:"name,omitempty"`
	Description string `json:"description,omitempty"`
}

// UpdateProjectRequest represents a request to update a project.
type UpdateProjectRequest struct {
	Name        string `json:"name"`
	Description string `json:"description"`
}

// HandleListProjects lists all projects.
func (s *Server) HandleListProjects(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	projects, err := s.projects.List(ctx)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to list projects")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to list projects")
		return
	}

	response := make([]ProjectResponse, len(projects))
	for i, p := range projects {
		response[i] = projectToResponse(p)
	}

	writeJSON(w, http.StatusOK, response)
}

// HandleCreateProject creates a new project.
func (s *Server) HandleCreateProject(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	var req CreateProjectRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_json", err.Error())
		return
	}

	if req.Code == "" {
		writeError(w, http.StatusBadRequest, "invalid_request", "Project code is required")
		return
	}

	// Validate project code format (2-10 alphanumeric characters)
	if len(req.Code) < 2 || len(req.Code) > 10 {
		writeError(w, http.StatusBadRequest, "invalid_code", "Project code must be 2-10 characters")
		return
	}

	project := &db.Project{
		Code:        req.Code,
		Name:        req.Name,
		Description: req.Description,
	}
	if user := auth.UserFromContext(ctx); user != nil {
		project.CreatedBy = &user.Username
	}

	if err := s.projects.Create(ctx, project); err != nil {
		s.logger.Error().Err(err).Msg("failed to create project")
		writeError(w, http.StatusInternalServerError, "create_failed", err.Error())
		return
	}

	writeJSON(w, http.StatusCreated, projectToResponse(project))
}

// HandleGetProject retrieves a project by code.
func (s *Server) HandleGetProject(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	code := chi.URLParam(r, "code")

	project, err := s.projects.GetByCode(ctx, code)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get project")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get project")
		return
	}
	if project == nil {
		writeError(w, http.StatusNotFound, "not_found", "Project not found")
		return
	}

	writeJSON(w, http.StatusOK, projectToResponse(project))
}

// HandleUpdateProject updates a project.
func (s *Server) HandleUpdateProject(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	code := chi.URLParam(r, "code")

	var req UpdateProjectRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_json", err.Error())
		return
	}

	if err := s.projects.Update(ctx, code, req.Name, req.Description); err != nil {
		s.logger.Error().Err(err).Msg("failed to update project")
		writeError(w, http.StatusInternalServerError, "update_failed", err.Error())
		return
	}

	project, _ := s.projects.GetByCode(ctx, code)
	writeJSON(w, http.StatusOK, projectToResponse(project))
}

// HandleDeleteProject deletes a project.
func (s *Server) HandleDeleteProject(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	code := chi.URLParam(r, "code")

	if err := s.projects.Delete(ctx, code); err != nil {
		s.logger.Error().Err(err).Msg("failed to delete project")
		writeError(w, http.StatusInternalServerError, "delete_failed", err.Error())
		return
	}

	w.WriteHeader(http.StatusNoContent)
}

// HandleGetProjectItems lists items in a project.
func (s *Server) HandleGetProjectItems(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	code := chi.URLParam(r, "code")

	project, err := s.projects.GetByCode(ctx, code)
	if err != nil || project == nil {
		writeError(w, http.StatusNotFound, "not_found", "Project not found")
		return
	}

	items, err := s.projects.GetItemsForProject(ctx, project.ID)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get project items")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get items")
		return
	}

	response := make([]ItemResponse, len(items))
	for i, item := range items {
		response[i] = itemToResponse(item)
	}

	writeJSON(w, http.StatusOK, response)
}

// HandleGetItemProjects lists projects for an item.
func (s *Server) HandleGetItemProjects(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil || item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	projects, err := s.projects.GetProjectsForItem(ctx, item.ID)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to get item projects")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get projects")
		return
	}

	response := make([]ProjectResponse, len(projects))
	for i, p := range projects {
		response[i] = projectToResponse(p)
	}

	writeJSON(w, http.StatusOK, response)
}

// AddItemProjectRequest represents a request to add projects to an item.
type AddItemProjectRequest struct {
	Projects []string `json:"projects"`
}

// HandleAddItemProjects adds project tags to an item.
func (s *Server) HandleAddItemProjects(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil || item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	var req AddItemProjectRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_json", err.Error())
		return
	}

	for _, code := range req.Projects {
		if err := s.projects.AddItemToProjectByCode(ctx, item.ID, code); err != nil {
			s.logger.Warn().Err(err).Str("project", code).Msg("failed to add project")
		}
	}

	// Return updated project list
	projects, _ := s.projects.GetProjectsForItem(ctx, item.ID)
	response := make([]ProjectResponse, len(projects))
	for i, p := range projects {
		response[i] = projectToResponse(p)
	}

	writeJSON(w, http.StatusOK, response)
}

// HandleRemoveItemProject removes a project tag from an item.
func (s *Server) HandleRemoveItemProject(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	partNumber := chi.URLParam(r, "partNumber")
	projectCode := chi.URLParam(r, "code")

	item, err := s.items.GetByPartNumber(ctx, partNumber)
	if err != nil || item == nil {
		writeError(w, http.StatusNotFound, "not_found", "Item not found")
		return
	}

	if err := s.projects.RemoveItemFromProjectByCode(ctx, item.ID, projectCode); err != nil {
		s.logger.Error().Err(err).Msg("failed to remove project")
		writeError(w, http.StatusInternalServerError, "remove_failed", err.Error())
		return
	}

	w.WriteHeader(http.StatusNoContent)
}

func projectToResponse(p *db.Project) ProjectResponse {
	return ProjectResponse{
		ID:          p.ID,
		Code:        p.Code,
		Name:        p.Name,
		Description: p.Description,
		CreatedAt:   p.CreatedAt.Format("2006-01-02T15:04:05Z07:00"),
	}
}