package lib

import (
	"database/sql"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"sort"
	"strings"

	"github.com/tursodatabase/go-libsql"
)

var DBClient *sql.DB

func InitDB() error {
	dbUrl := os.Getenv("DATABASE_URL")
	dbToken := os.Getenv("DATABASE_AUTH_TOKEN")

	if dbUrl == "" || dbToken == "" {
		return fmt.Errorf("database configuration missing")
	}

	connector, err := libsql.NewEmbeddedReplicaConnector(
		"./himbot.db",
		dbUrl,
		libsql.WithAuthToken(dbToken),
	)

	if err != nil {
		return fmt.Errorf("failed to create client: %w", err)
	}

	client := sql.OpenDB(connector)
	DBClient = client

	return runMigrations()
}

type Migration struct {
	Version int
	Up      string
	Down    string
}

func loadMigrations() ([]Migration, error) {
	var migrations []Migration
	migrationFiles, err := filepath.Glob("migrations/*.up.sql")
	if err != nil {
		return nil, fmt.Errorf("failed to read migration files: %w", err)
	}

	for _, upFile := range migrationFiles {
		// Extract version from filename (000001_create_users_table.up.sql -> 1)
		baseName := filepath.Base(upFile)
		version := 0
		fmt.Sscanf(baseName, "%d_", &version)

		downFile := strings.Replace(upFile, ".up.sql", ".down.sql", 1)

		upSQL, err := ioutil.ReadFile(upFile)
		if err != nil {
			return nil, fmt.Errorf("failed to read migration file %s: %w", upFile, err)
		}

		downSQL, err := ioutil.ReadFile(downFile)
		if err != nil {
			return nil, fmt.Errorf("failed to read migration file %s: %w", downFile, err)
		}

		migrations = append(migrations, Migration{
			Version: version,
			Up:      string(upSQL),
			Down:    string(downSQL),
		})
	}

	sort.Slice(migrations, func(i, j int) bool {
		return migrations[i].Version < migrations[j].Version
	})

	return migrations, nil
}

func runMigrations() error {
	// Create migrations table if it doesn't exist
	_, err := DBClient.Exec(`
		CREATE TABLE IF NOT EXISTS schema_migrations (
			version INTEGER PRIMARY KEY,
			applied_at DATETIME DEFAULT CURRENT_TIMESTAMP
		)`)
	if err != nil {
		return fmt.Errorf("failed to create schema_migrations table: %w", err)
	}

	migrations, err := loadMigrations()
	if err != nil {
		return err
	}

	for _, migration := range migrations {
		var exists bool
		err := DBClient.QueryRow(
			"SELECT EXISTS(SELECT 1 FROM schema_migrations WHERE version = ?)",
			migration.Version).Scan(&exists)
		if err != nil {
			return fmt.Errorf("failed to check migration status: %w", err)
		}

		if !exists {
			tx, err := DBClient.Begin()
			if err != nil {
				return fmt.Errorf("failed to start transaction: %w", err)
			}

			// Run migration
			_, err = tx.Exec(migration.Up)
			if err != nil {
				tx.Rollback()
				return fmt.Errorf("failed to apply migration %d: %w", migration.Version, err)
			}

			// Record migration
			_, err = tx.Exec(
				"INSERT INTO schema_migrations (version) VALUES (?)",
				migration.Version)
			if err != nil {
				tx.Rollback()
				return fmt.Errorf("failed to record migration %d: %w", migration.Version, err)
			}

			err = tx.Commit()
			if err != nil {
				return fmt.Errorf("failed to commit migration %d: %w", migration.Version, err)
			}

			log.Printf("Applied migration %d", migration.Version)
		}
	}

	log.Println("Database migrations completed successfully")
	return nil
}

func StoreUser(discordID, username string) error {
	// Check if user exists
	var exists bool
	err := DBClient.QueryRow(
		"SELECT EXISTS(SELECT 1 FROM users WHERE discord_id = ?)",
		discordID).Scan(&exists)
	if err != nil {
		return fmt.Errorf("failed to check user existence: %w", err)
	}

	// If user doesn't exist, insert them
	if !exists {
		_, err = DBClient.Exec(
			"INSERT INTO users (discord_id, username) VALUES (?, ?)",
			discordID, username)
		if err != nil {
			return fmt.Errorf("failed to store user: %w", err)
		}
		log.Printf("New user stored: %s (%s)", username, discordID)
	}

	return nil
}