package api

import (
	"encoding/json"
	"net/http"
	"strings"

	"github.com/go-chi/chi/v5"
	"github.com/kindredsystems/silo/internal/db"
)

// LocationResponse is the API representation of a location.
type LocationResponse struct {
	ID           string         `json:"id"`
	Path         string         `json:"path"`
	Name         string         `json:"name"`
	ParentID     *string        `json:"parent_id,omitempty"`
	LocationType string         `json:"location_type"`
	Depth        int            `json:"depth"`
	Metadata     map[string]any `json:"metadata,omitempty"`
	CreatedAt    string         `json:"created_at"`
}

// CreateLocationRequest represents a request to create a location.
type CreateLocationRequest struct {
	Path         string         `json:"path"`
	Name         string         `json:"name"`
	LocationType string         `json:"location_type"`
	Metadata     map[string]any `json:"metadata,omitempty"`
}

// UpdateLocationRequest represents a request to update a location.
type UpdateLocationRequest struct {
	Name         string         `json:"name"`
	LocationType string         `json:"location_type"`
	Metadata     map[string]any `json:"metadata,omitempty"`
}

func locationToResponse(loc *db.Location) LocationResponse {
	return LocationResponse{
		ID:           loc.ID,
		Path:         loc.Path,
		Name:         loc.Name,
		ParentID:     loc.ParentID,
		LocationType: loc.LocationType,
		Depth:        loc.Depth,
		Metadata:     loc.Metadata,
		CreatedAt:    loc.CreatedAt.Format("2006-01-02T15:04:05Z07:00"),
	}
}

// HandleListLocations lists all locations. If ?tree={path} is set, returns that
// subtree. If ?root=true, returns only root-level locations (depth 0).
func (s *Server) HandleListLocations(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	treePath := r.URL.Query().Get("tree")
	if treePath != "" {
		locs, err := s.locations.GetTree(ctx, treePath)
		if err != nil {
			s.logger.Error().Err(err).Str("tree", treePath).Msg("failed to get location tree")
			writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get location tree")
			return
		}
		writeJSON(w, http.StatusOK, locationsToResponse(locs))
		return
	}

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

	writeJSON(w, http.StatusOK, locationsToResponse(locs))
}

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

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

	if req.Path == "" {
		writeError(w, http.StatusBadRequest, "invalid_request", "Path is required")
		return
	}
	if req.Name == "" {
		writeError(w, http.StatusBadRequest, "invalid_request", "Name is required")
		return
	}
	if req.LocationType == "" {
		writeError(w, http.StatusBadRequest, "invalid_request", "Location type is required")
		return
	}

	// Normalize: trim slashes
	req.Path = strings.Trim(req.Path, "/")

	loc := &db.Location{
		Path:         req.Path,
		Name:         req.Name,
		LocationType: req.LocationType,
		Metadata:     req.Metadata,
	}
	if loc.Metadata == nil {
		loc.Metadata = map[string]any{}
	}

	if err := s.locations.Create(ctx, loc); err != nil {
		if strings.Contains(err.Error(), "parent location") || strings.Contains(err.Error(), "does not exist") {
			writeError(w, http.StatusBadRequest, "invalid_parent", err.Error())
			return
		}
		if strings.Contains(err.Error(), "duplicate key") || strings.Contains(err.Error(), "unique") {
			writeError(w, http.StatusConflict, "already_exists", "Location path already exists")
			return
		}
		s.logger.Error().Err(err).Str("path", req.Path).Msg("failed to create location")
		writeError(w, http.StatusInternalServerError, "create_failed", err.Error())
		return
	}

	writeJSON(w, http.StatusCreated, locationToResponse(loc))
}

// HandleGetLocation retrieves a location by path. The path is the rest of the
// URL after /api/locations/, which chi captures as a wildcard.
func (s *Server) HandleGetLocation(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	path := strings.Trim(chi.URLParam(r, "*"), "/")

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

	loc, err := s.locations.GetByPath(ctx, path)
	if err != nil {
		s.logger.Error().Err(err).Str("path", path).Msg("failed to get location")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to get location")
		return
	}
	if loc == nil {
		writeError(w, http.StatusNotFound, "not_found", "Location not found")
		return
	}

	writeJSON(w, http.StatusOK, locationToResponse(loc))
}

// HandleUpdateLocation updates a location by path.
func (s *Server) HandleUpdateLocation(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	path := strings.Trim(chi.URLParam(r, "*"), "/")

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

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

	if req.Name == "" {
		writeError(w, http.StatusBadRequest, "invalid_request", "Name is required")
		return
	}
	if req.LocationType == "" {
		writeError(w, http.StatusBadRequest, "invalid_request", "Location type is required")
		return
	}

	meta := req.Metadata
	if meta == nil {
		meta = map[string]any{}
	}

	if err := s.locations.Update(ctx, path, req.Name, req.LocationType, meta); err != nil {
		if strings.Contains(err.Error(), "not found") {
			writeError(w, http.StatusNotFound, "not_found", "Location not found")
			return
		}
		s.logger.Error().Err(err).Str("path", path).Msg("failed to update location")
		writeError(w, http.StatusInternalServerError, "update_failed", err.Error())
		return
	}

	loc, _ := s.locations.GetByPath(ctx, path)
	writeJSON(w, http.StatusOK, locationToResponse(loc))
}

// HandleDeleteLocation deletes a location by path. Rejects if inventory exists.
func (s *Server) HandleDeleteLocation(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	path := strings.Trim(chi.URLParam(r, "*"), "/")

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

	if err := s.locations.Delete(ctx, path); err != nil {
		if strings.Contains(err.Error(), "inventory record") {
			writeError(w, http.StatusConflict, "has_inventory", err.Error())
			return
		}
		if strings.Contains(err.Error(), "not found") {
			writeError(w, http.StatusNotFound, "not_found", "Location not found")
			return
		}
		s.logger.Error().Err(err).Str("path", path).Msg("failed to delete location")
		writeError(w, http.StatusInternalServerError, "delete_failed", err.Error())
		return
	}

	w.WriteHeader(http.StatusNoContent)
}

func locationsToResponse(locs []*db.Location) []LocationResponse {
	result := make([]LocationResponse, len(locs))
	for i, l := range locs {
		result[i] = locationToResponse(l)
	}
	return result
}