package cmd

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"strings"
	"time"

	"github.com/spf13/cobra"
	"github.com/yourorg/devour/internal/projectstate"
	"github.com/yourorg/devour/internal/scraper"
	"github.com/yourorg/devour/internal/search"
	"github.com/yourorg/devour/internal/storage"
)

var syncCmd = &cobra.Command{
	Use:   "sync",
	Short: "Synchronize with configured sources",
	Long: `Fetch updates from all configured sources.

Checks each source for changes (using hash or timestamp comparison)
and updates the local docs + index accordingly.

Examples:
  devour sync                    # Sync all sources
  devour sync --source my-docs   # Sync specific source
  devour sync --rebuild          # Full rebuild`,
	RunE: runSync,
}

var (
	syncSource  string
	syncRebuild bool
	syncForce   bool
)

func init() {
	syncCmd.Flags().StringVarP(&syncSource, "source", "s", "", "sync specific source only")
	syncCmd.Flags().BoolVar(&syncRebuild, "rebuild", false, "rebuild entire index")
	syncCmd.Flags().BoolVarP(&syncForce, "force", "f", false, "force sync even if no changes detected")
}

func runSync(cmd *cobra.Command, args []string) error {
	cfg, err := loadAppConfig()
	if err != nil {
		return err
	}

	if syncRebuild {
		fmt.Println("🔄 Rebuilding local index from configured sources...")
	} else {
		fmt.Println("🔄 Syncing configured sources...")
	}

	if len(cfg.Sources) == 0 {
		fmt.Println("No sources configured. Add sources in devour.yaml first.")
		return nil
	}

	state, err := projectstate.LoadSourceState(cfg.Storage.MetadataDir)
	if err != nil {
		return err
	}

	updated := 0
	skipped := 0
	failed := 0
	totalDocs := 0

	for _, srcCfg := range cfg.Sources {
		if syncSource != "" && srcCfg.Name != syncSource {
			continue
		}

		source := sourceFromConfig(srcCfg)
		if source.Type == "" {
			if source.URL != "" {
				source.Type = detectSourceType(source.URL)
			} else if source.Path != "" {
				source.Type = scraper.SourceTypeLocal
			}
		}
		if source.Name == "" {
			source.Name = extractName(source.URL)
		}
		applySourceProfile(source)

		fmt.Printf("\n• %s (%s)\n", source.Name, source.Type)
		s := scraper.NewScraper(source.Type, toScraperConfig(cfg, 0))
		if s == nil {
			failed++
			fmt.Printf("  ✗ unsupported source type: %s\n", source.Type)
			continue
		}

		key := source.Name
		if key == "" {
			key = chooseSourceLabel(source)
		}
		lastHash := ""
		if prev := state.Sources[key]; prev != nil {
			lastHash = prev.Hash
		}

		needsUpdate := syncForce || syncRebuild
		newHash := lastHash
		if !needsUpdate {
			changed, hash, detectErr := s.DetectChanges(context.Background(), source, lastHash)
			if detectErr != nil {
				fmt.Printf("  ⚠ change detection failed (%v), scraping anyway\n", detectErr)
				needsUpdate = true
			} else {
				needsUpdate = changed
				newHash = hash
			}
		}

		if !needsUpdate {
			skipped++
			fmt.Println("  ✓ no changes")
			continue
		}

		docs, scrapeErr := s.Scrape(context.Background(), source)
		if scrapeErr != nil {
			failed++
			fmt.Printf("  ✗ scrape failed: %v\n", scrapeErr)
			state.Sources[key] = &projectstate.SourceState{
				Name:      source.Name,
				Type:      string(source.Type),
				URL:       source.URL,
				Hash:      lastHash,
				LastSync:  time.Now(),
				DocCount:  0,
				LastError: scrapeErr.Error(),
			}
			continue
		}

		saved, saveErr := storage.SaveDocuments(docs, storage.SaveOptions{
			Format:      "json",
			OutputDir:   cfg.Storage.DocsDir,
			AllowEmpty:  false,
			PrintWriter: nil,
		})
		if saveErr != nil {
			failed++
			fmt.Printf("  ✗ save failed: %v\n", saveErr)
			continue
		}

		if newHash == "" {
			h := sha256.New()
			for _, d := range docs {
				if d == nil {
					continue
				}
				fmt.Fprintf(h, "%s|%s|%s\n", d.ID, d.Hash, d.URL)
			}
			newHash = hex.EncodeToString(h.Sum(nil))
		}

		state.Sources[key] = &projectstate.SourceState{
			Name:      source.Name,
			Type:      string(source.Type),
			URL:       source.URL,
			Hash:      newHash,
			LastSync:  time.Now(),
			DocCount:  saved.Count,
			LastError: "",
		}

		updated++
		totalDocs += saved.Count
		fmt.Printf("  ✓ updated (%d docs)\n", saved.Count)
	}

	if err := projectstate.SaveSourceState(cfg.Storage.MetadataDir, state); err != nil {
		return err
	}

	if syncRebuild || updated > 0 {
		engine := search.NewEngine(cfg)
		if _, err := engine.Rebuild(context.Background()); err != nil {
			return fmt.Errorf("rebuild index: %w", err)
		}
	}

	fmt.Printf("\nSync summary: updated=%d skipped=%d failed=%d docs=%d\n", updated, skipped, failed, totalDocs)
	if failed > 0 {
		return fmt.Errorf("sync completed with failures")
	}
	if syncSource != "" && updated == 0 && skipped == 0 && failed == 0 {
		return fmt.Errorf("source %q not found in config", syncSource)
	}
	if strings.TrimSpace(syncSource) != "" {
		fmt.Printf("Synced source: %s\n", syncSource)
	}
	return nil
}