package main

import (
	"database/sql"
	"errors"
	"fmt"
	"log"
	"os"
	"path/filepath"

	"github.com/golang-migrate/migrate/v4"
	"github.com/golang-migrate/migrate/v4/database/sqlite3"
	_ "github.com/golang-migrate/migrate/v4/source/file"
	_ "github.com/mattn/go-sqlite3"
	"github.com/spf13/cobra"
	"github.com/spf13/viper"
)

var (
	migrationsDir string
	steps         int
)

var migrateCmd = &cobra.Command{
	Use:   "migrate",
	Short: "Manage database migrations",
	Long:  `Commands for managing database migrations in the MCIAS system.`,
}

var migrateUpCmd = &cobra.Command{
	Use:   "up [steps]",
	Short: "Apply migrations",
	Long: `Apply all or a specific number of migrations.
If steps is not provided, all pending migrations will be applied.`,
	Run: func(cmd *cobra.Command, args []string) {
		runMigration("up", steps)
	},
}

var migrateDownCmd = &cobra.Command{
	Use:   "down [steps]",
	Short: "Revert migrations",
	Long: `Revert all or a specific number of migrations.
If steps is not provided, all applied migrations will be reverted.`,
	Run: func(cmd *cobra.Command, args []string) {
		runMigration("down", steps)
	},
}

var migrateVersionCmd = &cobra.Command{
	Use:   "version",
	Short: "Show current migration version",
	Long:  `Display the current migration version of the database.`,
	Run: func(cmd *cobra.Command, args []string) {
		showMigrationVersion()
	},
}

func init() {
	rootCmd.AddCommand(migrateCmd)
	migrateCmd.AddCommand(migrateUpCmd)
	migrateCmd.AddCommand(migrateDownCmd)
	migrateCmd.AddCommand(migrateVersionCmd)

	migrateCmd.PersistentFlags().StringVarP(&migrationsDir, "migrations", "m", "database/migrations", "Directory containing migration files")
	migrateCmd.PersistentFlags().IntVarP(&steps, "steps", "s", 0, "Number of migrations to apply or revert (0 means all)")
}

func runMigration(direction string, steps int) {
	dbPath := viper.GetString("db")
	logger := log.New(os.Stdout, "MCIAS Migration: ", log.LstdFlags)

	absPath, err := filepath.Abs(migrationsDir)
	if err != nil {
		logger.Fatalf("Failed to get absolute path for migrations directory: %v", err)
	}

	if _, err := os.Stat(absPath); os.IsNotExist(err) {
		logger.Fatalf("Migrations directory does not exist: %s", absPath)
	}

	db, err := openDatabase(dbPath)
	if err != nil {
		logger.Fatalf("Failed to open database: %v", err)
	}
	defer db.Close()

	driver, err := sqlite3.WithInstance(db, &sqlite3.Config{})
	if err != nil {
		logger.Fatalf("Failed to create migration driver: %v", err)
	}

	m, err := migrate.NewWithDatabaseInstance(
		fmt.Sprintf("file://%s", absPath),
		"sqlite3", driver)
	if err != nil {
		logger.Fatalf("Failed to create migration instance: %v", err)
	}

	if direction == "up" {
		if steps > 0 {
			err = m.Steps(steps)
		} else {
			err = m.Up()
		}
		if err != nil && !errors.Is(err, migrate.ErrNoChange) {
			logger.Fatalf("Failed to apply migrations: %v", err)
		}
		logger.Println("Migrations applied successfully")
	} else if direction == "down" {
		if steps > 0 {
			err = m.Steps(-steps)
		} else {
			err = m.Down()
		}
		if err != nil && !errors.Is(err, migrate.ErrNoChange) {
			logger.Fatalf("Failed to revert migrations: %v", err)
		}
		logger.Println("Migrations reverted successfully")
	}
}

func showMigrationVersion() {
	dbPath := viper.GetString("db")
	logger := log.New(os.Stdout, "MCIAS Migration: ", log.LstdFlags)

	db, err := openDatabase(dbPath)
	if err != nil {
		logger.Fatalf("Failed to open database: %v", err)
	}
	defer db.Close()

	driver, err := sqlite3.WithInstance(db, &sqlite3.Config{})
	if err != nil {
		logger.Fatalf("Failed to create migration driver: %v", err)
	}

	absPath, err := filepath.Abs(migrationsDir)
	if err != nil {
		logger.Fatalf("Failed to get absolute path for migrations directory: %v", err)
	}

	m, err := migrate.NewWithDatabaseInstance(
		fmt.Sprintf("file://%s", absPath),
		"sqlite3", driver)
	if err != nil {
		logger.Fatalf("Failed to create migration instance: %v", err)
	}

	version, dirty, err := m.Version()
	if err != nil {
		if errors.Is(err, migrate.ErrNilVersion) {
			logger.Println("No migrations have been applied yet")
			return
		}
		logger.Fatalf("Failed to get migration version: %v", err)
	}

	logger.Printf("Current migration version: %d (dirty: %t)", version, dirty)
}

func openDatabase(dbPath string) (*sql.DB, error) {
	dbDir := filepath.Dir(dbPath)
	if err := os.MkdirAll(dbDir, 0755); err != nil {
		return nil, fmt.Errorf("failed to create database directory: %w", err)
	}

	db, err := sql.Open("sqlite3", dbPath)
	if err != nil {
		return nil, fmt.Errorf("failed to open database: %w", err)
	}

	return db, nil
}