package common

import (
	"context"
	"database/sql"
	"embed"
	"fmt"
	"log/slog"
	"path"
	"regexp"
	"strconv"
	"strings"

	"github.com/nyttikord/avl"
)

var regexpMigration = regexp.MustCompile(`(\d{3})-(.*)\.sql`)

type migrationData struct {
	id      uint64
	name    string
	content string
}

func Migrate(ctx context.Context, log *slog.Logger, db *sql.DB, migrations embed.FS, dir string) error {
	entries, err := migrations.ReadDir(dir)
	if err != nil {
		return err
	}
	tree := avl.NewKeySimple[uint64, migrationData]()
	for _, entry := range entries {
		if strings.HasSuffix(entry.Name(), ".sql") {
			log.Debug("reading migration...", "path", dir+"/"+entry.Name())
			subs := regexpMigration.FindStringSubmatch(entry.Name())
			if len(subs) < 3 {
				return fmt.Errorf("invalid migration name %s", entry.Name())
			}
			id, _ := strconv.ParseUint(subs[1], 10, 16)
			b, err := migrations.ReadFile(path.Join(dir, entry.Name()))
			if err != nil {
				return err
			}
			tree.Insert(id, migrationData{id, subs[2], string(b)})
		} else {
			log.Warn("invalid migration entry, skipping", "path", dir+"/"+entry.Name())
		}
	}
	for _, mig := range tree.Sort() {
		log.Debug("migrating...", "id", mig.id, "name", mig.name)
		_, err := db.ExecContext(ctx, mig.content)
		if err != nil {
			log.Error("migrating", "id", mig.id, "name", mig.name)
			return err
		}
	}
	return nil
}