// Package factory provides functions for creating storage backends based on configuration.
package factory

import (
	"context"
	"fmt"
	"path/filepath"
	"time"

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

// BackendFactory is a function that creates a storage backend
type BackendFactory func(ctx context.Context, path string, opts Options) (storage.Storage, error)

// backendRegistry holds registered backend factories
var backendRegistry = make(map[string]BackendFactory)

// RegisterBackend registers a storage backend factory
func RegisterBackend(name string, factory BackendFactory) {
	backendRegistry[name] = factory
}

// Options configures how the storage backend is opened
type Options struct {
	ReadOnly    bool
	LockTimeout time.Duration
}

// New creates a storage backend based on the backend type.
// For SQLite, path should be the full path to the .db file.
// For Dolt, path should be the directory containing the Dolt database.
func New(ctx context.Context, backend, path string) (storage.Storage, error) {
	return NewWithOptions(ctx, backend, path, Options{})
}

// NewWithOptions creates a storage backend with the specified options.
func NewWithOptions(ctx context.Context, backend, path string, opts Options) (storage.Storage, error) {
	switch backend {
	case configfile.BackendSQLite, "":
		if opts.ReadOnly {
			if opts.LockTimeout > 0 {
				return sqlite.NewReadOnlyWithTimeout(ctx, path, opts.LockTimeout)
			}
			return sqlite.NewReadOnly(ctx, path)
		}
		if opts.LockTimeout > 0 {
			return sqlite.NewWithTimeout(ctx, path, opts.LockTimeout)
		}
		return sqlite.New(ctx, path)
	default:
		// Check if backend is registered (e.g., dolt with CGO)
		if factory, ok := backendRegistry[backend]; ok {
			return factory(ctx, path, opts)
		}
		// Provide helpful error for dolt on systems without CGO
		if backend == configfile.BackendDolt {
			return nil, fmt.Errorf("dolt backend requires CGO (not available on this build); use sqlite backend or install from pre-built binaries")
		}
		return nil, fmt.Errorf("unknown storage backend: %s (supported: sqlite, dolt)", backend)
	}
}

// NewFromConfig creates a storage backend based on the metadata.json configuration.
// beadsDir is the path to the .beads directory.
func NewFromConfig(ctx context.Context, beadsDir string) (storage.Storage, error) {
	return NewFromConfigWithOptions(ctx, beadsDir, Options{})
}

// NewFromConfigWithOptions creates a storage backend with options from metadata.json.
func NewFromConfigWithOptions(ctx context.Context, beadsDir string, opts Options) (storage.Storage, error) {
	cfg, err := configfile.Load(beadsDir)
	if err != nil {
		return nil, fmt.Errorf("loading config: %w", err)
	}
	if cfg == nil {
		cfg = configfile.DefaultConfig()
	}

	backend := cfg.GetBackend()
	switch backend {
	case configfile.BackendSQLite:
		return NewWithOptions(ctx, backend, cfg.DatabasePath(beadsDir), opts)
	case configfile.BackendDolt:
		// For Dolt, use a subdirectory to store the Dolt database
		doltPath := filepath.Join(beadsDir, "dolt")
		return NewWithOptions(ctx, backend, doltPath, opts)
	default:
		return nil, fmt.Errorf("unknown storage backend in config: %s", backend)
	}
}

// GetBackendFromConfig returns the backend type from metadata.json
func GetBackendFromConfig(beadsDir string) string {
	cfg, err := configfile.Load(beadsDir)
	if err != nil || cfg == nil {
		return configfile.BackendSQLite
	}
	return cfg.GetBackend()
}