package mysqlite

import (
	"database/sql"
	"embed"
	"fmt"
	"io/fs"
	"log"
	"strconv"
	"strings"
	"zombiezen.com/go/sqlite"
)

type ReadDirFileFS interface {
	fs.ReadDirFS
	fs.ReadFileFS
}

func (db *Db) MigrateDb(migrations ReadDirFileFS) error {
	// Read all migrations
	migrationFiles, err := migrations.ReadDir("")
	if err != nil {
		log.Fatalf("error reading migration files: %v", err)
	}
	var migrationsByVersion = make(map[int]string)
	latestVersion := 0
	for _, f := range migrationFiles {
		versionStr := f.Name()
		version, err := strconv.Atoi(strings.SplitN(versionStr, "_", 2)[0])
		if err != nil {
			log.Fatalf("invalid version number for migration script: %v", err)
		}
		migrationsByVersion[version] = versionStr
		latestVersion = max(latestVersion, version)
	}

	// Get current migration version from user_version
	var currentVersion int
	err = d.QuerySingle("PRAGMA user_version", &currentVersion)
	if err != nil {
		log.Fatalf("error getting current version: %v", err)
	}
	log.Printf("Current database migration version is %d, latest version is %d", currentVersion, latestVersion)

	// If we are no up-to-date, bring the db up-to-date
	for currentVersion != latestVersion {
		targetVersion := currentVersion + 1
		migrationFile := migrationsByVersion[targetVersion]
		log.Printf("migration to version %s", migrationFile)
		migrationScript, err := migrations.ReadFile(migrationFile)
		if err != nil {
			log.Fatalf("error opening migration script %s: %v", migrationScript, err)
		}

		tx, err := db.Begin()
		if err != nil {
			log.Fatalf("error beginning transaction: %v", err)
		}
		defer tx.MustRollback()

		err = tx.QuerySingle(string(migrationScript))
		if err != nil {
			log.Fatalf("error performing migration: %v", err)
		}

		err = tx.QuerySingle(fmt.Sprintf("PRAGMA user_version = %d", targetVersion))
		if err != nil {
			log.Fatalf("error updating version: %v", err)
		}

		err = tx.Commit()
		if err != nil {
			log.Fatalf("error commiting transaction: %v", err)
		}
		currentVersion = targetVersion
	}

	log.Println("All migrations applied")
	return nil
}

func rollbackIgnoringErrors(tx *sql.Tx) {
	err := tx.Rollback()
	if err != nil {
		log.Printf("error rolling back: %v", err)
	}
}