package fix

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/steveyegge/beads/internal/configfile"
)

// DatabaseConfig auto-detects and fixes metadata.json database/JSONL config mismatches.
// This fixes the issue where metadata.json gets recreated with wrong JSONL filename.
//
// bd-afd: bd doctor --fix should auto-fix metadata.json jsonl_export mismatch
func DatabaseConfig(path string) error {
	if err := validateBeadsWorkspace(path); err != nil {
		return err
	}

	beadsDir := filepath.Join(path, ".beads")

	// Load existing config
	cfg, err := configfile.Load(beadsDir)
	if err != nil {
		return fmt.Errorf("failed to load config: %w", err)
	}
	if cfg == nil {
		// No config exists - nothing to fix
		return fmt.Errorf("no metadata.json found")
	}

	fixed := false

	// Check if configured JSONL exists
	if cfg.JSONLExport != "" {
		jsonlPath := cfg.JSONLPath(beadsDir)
		if _, err := os.Stat(jsonlPath); os.IsNotExist(err) {
			// Config points to non-existent file - try to find actual JSONL
			actualJSONL := findActualJSONLFile(beadsDir)
			if actualJSONL != "" {
				fmt.Printf("  Updating jsonl_export: %s → %s\n", cfg.JSONLExport, actualJSONL)
				cfg.JSONLExport = actualJSONL
				fixed = true
			}
		}
	}

	// Check if configured database exists
	if cfg.Database != "" {
		dbPath := cfg.DatabasePath(beadsDir)
		if _, err := os.Stat(dbPath); os.IsNotExist(err) {
			// Config points to non-existent file - try to find actual database
			actualDB := findActualDBFile(beadsDir)
			if actualDB != "" {
				fmt.Printf("  Updating database: %s → %s\n", cfg.Database, actualDB)
				cfg.Database = actualDB
				fixed = true
			}
		}
	}

	if !fixed {
		return fmt.Errorf("no configuration mismatches detected")
	}

	// Save updated config
	if err := cfg.Save(beadsDir); err != nil {
		return fmt.Errorf("failed to save config: %w", err)
	}

	return nil
}

// findActualJSONLFile scans .beads/ for the actual JSONL file in use.
// Prefers beads.jsonl over issues.jsonl, skips backups and merge artifacts.
func findActualJSONLFile(beadsDir string) string {
	entries, err := os.ReadDir(beadsDir)
	if err != nil {
		return ""
	}

	var candidates []string
	for _, entry := range entries {
		if entry.IsDir() {
			continue
		}
		name := entry.Name()

		// Must end with .jsonl
		if !strings.HasSuffix(name, ".jsonl") {
			continue
		}

		// Skip merge artifacts and backups
		lowerName := strings.ToLower(name)
		if strings.Contains(lowerName, "backup") ||
			strings.Contains(lowerName, ".orig") ||
			strings.Contains(lowerName, ".bak") ||
			strings.Contains(lowerName, "~") ||
			strings.HasPrefix(lowerName, "backup_") {
			continue
		}

		candidates = append(candidates, name)
	}

	if len(candidates) == 0 {
		return ""
	}

	// Prefer beads.jsonl over issues.jsonl (canonical name)
	for _, name := range candidates {
		if name == "beads.jsonl" {
			return name
		}
	}

	// Fall back to first candidate
	return candidates[0]
}

// findActualDBFile scans .beads/ for the actual database file in use.
// Prefers beads.db (canonical name), skips backups and vc.db.
func findActualDBFile(beadsDir string) string {
	entries, err := os.ReadDir(beadsDir)
	if err != nil {
		return ""
	}

	var candidates []string
	for _, entry := range entries {
		if entry.IsDir() {
			continue
		}
		name := entry.Name()

		// Must end with .db
		if !strings.HasSuffix(name, ".db") {
			continue
		}

		// Skip backups and vc.db
		if strings.Contains(name, "backup") || name == "vc.db" {
			continue
		}

		candidates = append(candidates, name)
	}

	if len(candidates) == 0 {
		return ""
	}

	// Prefer beads.db (canonical name)
	for _, name := range candidates {
		if name == "beads.db" {
			return name
		}
	}

	// Fall back to first candidate
	return candidates[0]
}