package api

import (
	"context"
	"crypto/rand"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"net/http"

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

// HandleRunnerHeartbeat updates the runner's heartbeat timestamp.
func (s *Server) HandleRunnerHeartbeat(w http.ResponseWriter, r *http.Request) {
	runner := auth.RunnerFromContext(r.Context())
	if runner == nil {
		writeError(w, http.StatusUnauthorized, "unauthorized", "Runner identity required")
		return
	}

	// Heartbeat already updated by RequireRunnerAuth middleware
	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
}

// HandleRunnerClaim claims the next available job matching the runner's tags.
func (s *Server) HandleRunnerClaim(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	runner := auth.RunnerFromContext(ctx)
	if runner == nil {
		writeError(w, http.StatusUnauthorized, "unauthorized", "Runner identity required")
		return
	}

	job, err := s.jobs.ClaimJob(ctx, runner.ID, runner.Tags)
	if err != nil {
		s.logger.Error().Err(err).Msg("failed to claim job")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to claim job")
		return
	}
	if job == nil {
		writeJSON(w, http.StatusNoContent, nil)
		return
	}

	// Look up the full definition to send to the runner
	var defPayload map[string]any
	if job.JobDefinitionID != nil {
		rec, err := s.jobs.GetDefinitionByID(ctx, *job.JobDefinitionID)
		if err == nil && rec != nil {
			defPayload = rec.Definition
		}
	}

	s.broker.Publish("job.claimed", mustMarshal(map[string]any{
		"job_id":    job.ID,
		"runner_id": runner.ID,
		"runner":    runner.Name,
	}))

	writeJSON(w, http.StatusOK, map[string]any{
		"job":        job,
		"definition": defPayload,
	})
}

// HandleRunnerStartJob transitions a claimed job to running.
func (s *Server) HandleRunnerStartJob(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	runner := auth.RunnerFromContext(ctx)
	if runner == nil {
		writeError(w, http.StatusUnauthorized, "unauthorized", "Runner identity required")
		return
	}

	jobID := chi.URLParam(r, "jobID")
	if err := s.jobs.StartJob(ctx, jobID, runner.ID); err != nil {
		writeError(w, http.StatusBadRequest, "start_failed", err.Error())
		return
	}

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

// HandleRunnerUpdateProgress updates a running job's progress.
func (s *Server) HandleRunnerUpdateProgress(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	runner := auth.RunnerFromContext(ctx)
	if runner == nil {
		writeError(w, http.StatusUnauthorized, "unauthorized", "Runner identity required")
		return
	}

	jobID := chi.URLParam(r, "jobID")
	var req struct {
		Progress int    `json:"progress"`
		Message  string `json:"message,omitempty"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_body", "Invalid JSON body")
		return
	}

	if err := s.jobs.UpdateProgress(ctx, jobID, runner.ID, req.Progress, req.Message); err != nil {
		writeError(w, http.StatusBadRequest, "update_failed", err.Error())
		return
	}

	s.broker.Publish("job.progress", mustMarshal(map[string]any{
		"job_id":   jobID,
		"progress": req.Progress,
		"message":  req.Message,
	}))

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

// HandleRunnerCompleteJob marks a job as completed.
func (s *Server) HandleRunnerCompleteJob(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	runner := auth.RunnerFromContext(ctx)
	if runner == nil {
		writeError(w, http.StatusUnauthorized, "unauthorized", "Runner identity required")
		return
	}

	jobID := chi.URLParam(r, "jobID")
	var req struct {
		Result map[string]any `json:"result,omitempty"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_body", "Invalid JSON body")
		return
	}

	if err := s.jobs.CompleteJob(ctx, jobID, runner.ID, req.Result); err != nil {
		writeError(w, http.StatusBadRequest, "complete_failed", err.Error())
		return
	}

	s.broker.Publish("job.completed", mustMarshal(map[string]any{
		"job_id":    jobID,
		"runner_id": runner.ID,
	}))

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

// HandleRunnerFailJob marks a job as failed.
func (s *Server) HandleRunnerFailJob(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	runner := auth.RunnerFromContext(ctx)
	if runner == nil {
		writeError(w, http.StatusUnauthorized, "unauthorized", "Runner identity required")
		return
	}

	jobID := chi.URLParam(r, "jobID")
	var req struct {
		Error string `json:"error"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_body", "Invalid JSON body")
		return
	}

	if err := s.jobs.FailJob(ctx, jobID, runner.ID, req.Error); err != nil {
		writeError(w, http.StatusBadRequest, "fail_failed", err.Error())
		return
	}

	s.broker.Publish("job.failed", mustMarshal(map[string]any{
		"job_id":    jobID,
		"runner_id": runner.ID,
		"error":     req.Error,
	}))

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

// HandleRunnerAppendLog appends a log entry to a job.
func (s *Server) HandleRunnerAppendLog(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	runner := auth.RunnerFromContext(ctx)
	if runner == nil {
		writeError(w, http.StatusUnauthorized, "unauthorized", "Runner identity required")
		return
	}

	jobID := chi.URLParam(r, "jobID")
	var req struct {
		Level    string         `json:"level"`
		Message  string         `json:"message"`
		Metadata map[string]any `json:"metadata,omitempty"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_body", "Invalid JSON body")
		return
	}

	if req.Level == "" {
		req.Level = "info"
	}

	entry := &db.JobLogEntry{
		JobID:    jobID,
		Level:    req.Level,
		Message:  req.Message,
		Metadata: req.Metadata,
	}
	if err := s.jobs.AppendLog(ctx, entry); err != nil {
		s.logger.Error().Err(err).Msg("failed to append job log")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to append log")
		return
	}

	writeJSON(w, http.StatusCreated, entry)
}

// HandleRunnerSyncDAG allows a runner to push DAG results for a job's item.
func (s *Server) HandleRunnerSyncDAG(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	runner := auth.RunnerFromContext(ctx)
	if runner == nil {
		writeError(w, http.StatusUnauthorized, "unauthorized", "Runner identity required")
		return
	}

	jobID := chi.URLParam(r, "jobID")

	// Get the job to find the item
	job, err := s.jobs.GetJob(ctx, jobID)
	if err != nil || job == nil {
		writeError(w, http.StatusNotFound, "not_found", "Job not found")
		return
	}
	if job.ItemID == nil {
		writeError(w, http.StatusBadRequest, "no_item", "Job has no associated item")
		return
	}

	// Delegate to the DAG sync handler logic
	var req dagSyncRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid_body", "Invalid JSON body")
		return
	}

	if req.RevisionNumber == 0 {
		// Look up current revision
		item, err := s.items.GetByID(ctx, *job.ItemID)
		if err != nil || item == nil {
			writeError(w, http.StatusNotFound, "not_found", "Item not found")
			return
		}
		req.RevisionNumber = item.CurrentRevision
	}

	// Convert and sync nodes
	nodes := make([]db.DAGNode, len(req.Nodes))
	for i, n := range req.Nodes {
		state := n.ValidationState
		if state == "" {
			state = "clean"
		}
		nodes[i] = db.DAGNode{
			NodeKey:         n.NodeKey,
			NodeType:        n.NodeType,
			PropertiesHash:  n.PropertiesHash,
			ValidationState: state,
			Metadata:        n.Metadata,
		}
	}

	if err := s.dag.SyncFeatureTree(ctx, *job.ItemID, req.RevisionNumber, nodes, nil); err != nil {
		s.logger.Error().Err(err).Msg("failed to sync DAG from runner")
		writeError(w, http.StatusInternalServerError, "internal_error", "Failed to sync DAG")
		return
	}

	// Build key→ID map and sync edges
	keyToID := make(map[string]string, len(nodes))
	for _, n := range nodes {
		keyToID[n.NodeKey] = n.ID
	}

	if len(req.Edges) > 0 {
		if err := s.dag.DeleteEdgesForItem(ctx, *job.ItemID, req.RevisionNumber); err != nil {
			s.logger.Error().Err(err).Msg("failed to delete old edges")
			writeError(w, http.StatusInternalServerError, "internal_error", "Failed to sync DAG edges")
			return
		}
		for _, e := range req.Edges {
			sourceID, ok := keyToID[e.SourceKey]
			if !ok {
				continue
			}
			targetID, ok := keyToID[e.TargetKey]
			if !ok {
				continue
			}
			edgeType := e.EdgeType
			if edgeType == "" {
				edgeType = "depends_on"
			}
			edge := &db.DAGEdge{
				SourceNodeID: sourceID,
				TargetNodeID: targetID,
				EdgeType:     edgeType,
				Metadata:     e.Metadata,
			}
			if err := s.dag.CreateEdge(ctx, edge); err != nil {
				s.logger.Error().Err(err).Msg("failed to create edge from runner")
			}
		}
	}

	s.broker.Publish("dag.updated", mustMarshal(map[string]any{
		"item_id":    *job.ItemID,
		"job_id":     jobID,
		"runner":     runner.Name,
		"node_count": len(req.Nodes),
		"edge_count": len(req.Edges),
	}))

	writeJSON(w, http.StatusOK, map[string]any{
		"synced":     true,
		"node_count": len(req.Nodes),
		"edge_count": len(req.Edges),
	})
}

// generateRunnerToken creates a new runner token. Returns raw token, hash, and prefix.
func generateRunnerToken() (raw, hash, prefix string) {
	rawBytes := make([]byte, 32)
	if _, err := rand.Read(rawBytes); err != nil {
		panic(fmt.Sprintf("generating random bytes: %v", err))
	}

	raw = "silo_runner_" + hex.EncodeToString(rawBytes)

	h := sha256.Sum256([]byte(raw))
	hash = hex.EncodeToString(h[:])

	prefix = raw[:20] // "silo_runner_" + first 8 hex chars

	return
}

// loadAndUpsertJobDefs loads YAML definitions from a directory and upserts them into the database.
func loadAndUpsertJobDefs(ctx context.Context, dir string, repo *db.JobRepository) (map[string]*jobdef.Definition, error) {
	defs, err := jobdef.LoadAll(dir)
	if err != nil {
		return nil, fmt.Errorf("loading job definitions: %w", err)
	}

	for _, def := range defs {
		defJSON, _ := json.Marshal(def)
		var defMap map[string]any
		json.Unmarshal(defJSON, &defMap)

		rec := &db.JobDefinitionRecord{
			Name:           def.Name,
			Version:        def.Version,
			TriggerType:    def.Trigger.Type,
			ScopeType:      def.Scope.Type,
			ComputeType:    def.Compute.Type,
			RunnerTags:     def.Runner.Tags,
			TimeoutSeconds: def.Timeout,
			MaxRetries:     def.MaxRetries,
			Priority:       def.Priority,
			Definition:     defMap,
			Enabled:        true,
		}
		if err := repo.UpsertDefinition(ctx, rec); err != nil {
			return nil, fmt.Errorf("upserting definition %s: %w", def.Name, err)
		}
	}

	return defs, nil
}