package database

import (
	"database/sql"
	"embed"
	"fmt"
	"log/slog"

	"github.com/golang-migrate/migrate/v4"
	"github.com/golang-migrate/migrate/v4/database/sqlite3"
	"github.com/golang-migrate/migrate/v4/source/iofs"
	_ "github.com/mattn/go-sqlite3"
)

//go:embed migrations/*.sql
var migrations embed.FS

func Open(dbPath string) (*sql.DB, error) {
	connStr := dbPath + "?_journal_mode=WAL&_foreign_keys=1"

	migrationDb, err := sql.Open("sqlite3", connStr)
	if err != nil {
		return nil, fmt.Errorf("open db for migrations: %w", err)
	}
	if err := migrationDb.Ping(); err != nil {
		migrationDb.Close()
		return nil, fmt.Errorf("ping db: %w", err)
	}
	if err := runMigrations(migrationDb); err != nil {
		migrationDb.Close()
		return nil, fmt.Errorf("run migrations: %w", err)
	}
	migrationDb.Close()

	db, err := sql.Open("sqlite3", connStr)
	if err != nil {
		return nil, fmt.Errorf("open db: %w", err)
	}
	if err := db.Ping(); err != nil {
		db.Close()
		return nil, fmt.Errorf("ping db: %w", err)
	}
	return db, nil
}

func runMigrations(db *sql.DB) error {
	sourceDriver, err := iofs.New(migrations, "migrations")
	if err != nil {
		return fmt.Errorf("create migration source: %w", err)
	}

	driver, err := sqlite3.WithInstance(db, &sqlite3.Config{})
	if err != nil {
		return fmt.Errorf("create database driver: %w", err)
	}

	m, err := migrate.NewWithInstance("iofs", sourceDriver, "sqlite3", driver)
	if err != nil {
		return fmt.Errorf("create migrate instance: %w", err)
	}
	defer m.Close()

	currentVersion, _, err := m.Version()
	if err != nil && err != migrate.ErrNilVersion {
		return fmt.Errorf("get current migration version: %w", err)
	}

	if err == migrate.ErrNilVersion {
		slog.Info("running database migrations", "currentVersion", "none")
	} else {
		slog.Info("running database migrations", "currentVersion", currentVersion)
	}

	upErr := m.Up()
	if upErr != nil && upErr != migrate.ErrNoChange {
		return fmt.Errorf("run migrations: %w", upErr)
	}

	newVersion, dirty, versionErr := m.Version()
	if versionErr != nil && versionErr != migrate.ErrNilVersion {
		return fmt.Errorf("get migration version after execution: %w", versionErr)
	}

	if upErr == migrate.ErrNoChange {
		slog.Info("no pending migrations", "currentVersion", currentVersion)
	} else if dirty {
		slog.Warn("migration completed but database is in dirty state", "version", newVersion)
	} else {
		if err == migrate.ErrNilVersion {
			slog.Info("migrations completed", "appliedVersion", newVersion)
		} else if currentVersion != newVersion {
			slog.Info("migrations completed", "fromVersion", currentVersion, "toVersion", newVersion)
		} else {
			slog.Info("migrations completed", "version", newVersion)
		}
	}

	return nil
}