package engine

import (
	"encoding/json"
	"fmt"
	"log/slog"
	"os"
	"path/filepath"
	"sort"
	"strings"

	"github.com/local/glpi-neural-brain/internal/graph"
	"github.com/local/glpi-neural-brain/internal/model"
)

type articleProvenanceMetadata struct {
	ArticleID             string   `json:"article_id"`
	Action                string   `json:"action"`
	TargetNodeID          string   `json:"target_node_id"`
	SourceNodeIDs         []string `json:"source_node_ids"`
	Confidence            float64  `json:"confidence"`
	GenerationDepth       int      `json:"generation_depth"`
	ProductiveSourceCount int      `json:"productive_source_count"`
	AISourceCount         int      `json:"ai_source_count"`
	ProductionRatio       float64  `json:"production_ratio"`
	SourceFingerprint     string   `json:"source_fingerprint"`
	SynthesisModel        string   `json:"synthesis_model"`
	ReviewModel           string   `json:"review_model"`
	Pipeline              string   `json:"pipeline"`
	Planning              struct {
		Reason string `json:"reason"`
	} `json:"planning"`
	GroundedResearch []struct {
		URL string `json:"url"`
	} `json:"grounded_research_evidence"`
}

// reconcileArticleProvenance repairs provenance edges that may have been lost
// by older staging reconciliation logic. article-metadata is the durable source
// of truth for source/target provenance after an accepted draft was written.
func (e *Engine) reconcileArticleProvenance() graph.MutationStats {
	var stats graph.MutationStats
	root := filepath.Join(e.Cfg.DataDir, "article-metadata")
	files, err := filepath.Glob(filepath.Join(root, "*.json"))
	if err != nil {
		slog.Warn("article provenance metadata glob failed", "error", err)
		return stats
	}
	snapshot := e.Graph.Snapshot()
	existing := make(map[string]bool, len(snapshot.Edges))
	for _, edge := range snapshot.Edges {
		existing[articleProvenanceSemanticKey(edge.Source, edge.Target, edge.Type)] = true
	}
	for _, path := range files {
		raw, err := os.ReadFile(path)
		if err != nil {
			continue
		}
		var meta articleProvenanceMetadata
		if err := json.Unmarshal(raw, &meta); err != nil || strings.TrimSpace(meta.ArticleID) == "" {
			continue
		}
		articleNodeID := graph.ID("knowledge", meta.ArticleID)
		articleNode, ok := e.Graph.GetNode(articleNodeID)
		if !ok {
			continue
		}
		if articleNode.Metadata == nil {
			articleNode.Metadata = map[string]any{}
		}
		// Older staging JSONs did not persist ai_think provenance. Restore the
		// structural metadata from the durable sidecar so restart/reimport cannot
		// erase source lineage or make readiness blind to missing edges.
		needsMetadataRepair := strings.TrimSpace(fmt.Sprint(articleNode.Metadata["subtype"])) != "knowledge_synthesis" ||
			strings.TrimSpace(fmt.Sprint(articleNode.Metadata["action"])) != strings.TrimSpace(meta.Action) ||
			strings.TrimSpace(fmt.Sprint(articleNode.Metadata["target_node_id"])) != strings.TrimSpace(meta.TargetNodeID) ||
			intMetadataValue(articleNode.Metadata["generation_depth"]) != meta.GenerationDepth ||
			strings.TrimSpace(fmt.Sprint(articleNode.Metadata["source_fingerprint"])) != strings.TrimSpace(meta.SourceFingerprint) ||
			!sameStringSet(engineStringSlice(articleNode.Metadata["source_node_ids"]), meta.SourceNodeIDs)
		if needsMetadataRepair {
			articleNode.Metadata["subtype"] = "knowledge_synthesis"
			articleNode.Metadata["action"] = meta.Action
			articleNode.Metadata["target_node_id"] = meta.TargetNodeID
			articleNode.Metadata["source_node_ids"] = append([]string(nil), meta.SourceNodeIDs...)
			articleNode.Metadata["confidence"] = meta.Confidence
			articleNode.Metadata["generation_depth"] = meta.GenerationDepth
			articleNode.Metadata["productive_source_count"] = meta.ProductiveSourceCount
			articleNode.Metadata["ai_source_count"] = meta.AISourceCount
			articleNode.Metadata["production_ratio"] = meta.ProductionRatio
			articleNode.Metadata["source_fingerprint"] = meta.SourceFingerprint
			articleNode.Metadata["synthesis_model"] = meta.SynthesisModel
			articleNode.Metadata["review_model"] = meta.ReviewModel
			articleNode.Metadata["pipeline"] = meta.Pipeline
			stats.Add(e.Graph.UpsertNodeWithStats(articleNode))
		}
		confidence := meta.Confidence
		if confidence <= 0 {
			confidence = .8
		}
		add := func(edge model.Edge) {
			edge.Origin = "knowledge-synthesis"
			edge.Status = "staging"
			if edge.Confidence == 0 {
				edge.Confidence = confidence
			}
			if edge.Weight == 0 {
				edge.Weight = .65
			}
			semanticKey := articleProvenanceSemanticKey(edge.Source, edge.Target, edge.Type)
			if existing[semanticKey] {
				return
			}
			edge.ID = graph.EdgeID(edge.Source, edge.Target, edge.Type, edge.Origin)
			stats.Add(e.Graph.UpsertEdgeWithStats(edge))
			existing[semanticKey] = true
		}
		for _, sourceID := range meta.SourceNodeIDs {
			sourceID = strings.TrimSpace(sourceID)
			if sourceID == "" {
				continue
			}
			if _, ok := e.Graph.GetNode(sourceID); !ok {
				continue
			}
			add(model.Edge{Source: articleNodeID, Target: sourceID, Type: "synthesized_from", Weight: .65, Explanation: meta.Planning.Reason})
		}
		if target := strings.TrimSpace(meta.TargetNodeID); target != "" {
			if _, ok := e.Graph.GetNode(target); ok {
				action := safeArticleAction(meta.Action)
				if action != "skip" {
					add(model.Edge{Source: articleNodeID, Target: target, Type: "proposes_" + action, Weight: .8, Explanation: meta.Planning.Reason})
				}
			}
		}
		for _, evidence := range meta.GroundedResearch {
			if strings.TrimSpace(evidence.URL) == "" {
				continue
			}
			researchID := graph.ID("external", evidence.URL)
			if _, ok := e.Graph.GetNode(researchID); ok {
				add(model.Edge{Source: articleNodeID, Target: researchID, Type: "grounded_by", Weight: .65, Explanation: "Persistierter, vom Reviewer verwendeter Beleg"})
			}
		}
	}
	return stats
}

func articleProvenanceSemanticKey(source, target, edgeType string) string {
	return strings.TrimSpace(source) + "\x00" + strings.TrimSpace(target) + "\x00" + strings.TrimSpace(edgeType)
}

func intMetadataValue(value any) int {
	switch v := value.(type) {
	case int:
		return v
	case int64:
		return int(v)
	case float64:
		return int(v)
	case float32:
		return int(v)
	default:
		return 0
	}
}

func engineStringSlice(value any) []string {
	switch values := value.(type) {
	case []string:
		return append([]string(nil), values...)
	case []any:
		out := make([]string, 0, len(values))
		for _, raw := range values {
			if text := strings.TrimSpace(fmt.Sprint(raw)); text != "" {
				out = append(out, text)
			}
		}
		return out
	default:
		return nil
	}
}

func sameStringSet(a, b []string) bool {
	a = append([]string(nil), a...)
	b = append([]string(nil), b...)
	for i := range a {
		a[i] = strings.TrimSpace(a[i])
	}
	for i := range b {
		b[i] = strings.TrimSpace(b[i])
	}
	sort.Strings(a)
	sort.Strings(b)
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}