package database

import (
	"errors"
	"fmt"
	"io/fs"
	"log/slog"
	"sort"
	"strings"

	"bunker/commons"
	"bunker/server/internal/services/core"

	"github.com/pressly/goose/v3"
)

var errMigrationsAlreadyRegistered = errors.New("migrations already registered")

func (d *database) applyMigrations() error {
	d.logger.Info("Migrating database...")

	modules := make([]string, 0)

	for module := range d.migrations {
		modules = append(modules, module)
	}

	sort.Strings(modules)

	_ = goose.SetDialect(string(goose.DialectPostgres))

	gooseLogger := commons.NewGooseLogger(d.logger)
	goose.SetLogger(gooseLogger)

	for _, module := range modules {
		d.logger.Info("Migrating database for module...", "module", module)

		goose.SetBaseFS(d.migrations[module])
		goose.SetTableName(strings.ReplaceAll(module, "/", "_") + "_migrations")

		if err := goose.Up(d.db.DB, "migrations"); err != nil {
			return fmt.Errorf("%w: applying migrations for module '%s': %w", core.ErrDatabase, module, err)
		}

		moduleDBVersion, err := goose.GetDBVersion(d.db.DB)
		if err != nil {
			return fmt.Errorf("%w: get database version for module '%s': %w", core.ErrDatabase, module, err)
		}

		d.version += moduleDBVersion

		d.logger.Info(
			"Database for module migrated to latest version",
			"module", module,
			"module_db_version", moduleDBVersion,
			"db_version", d.version,
		)
	}

	d.logger.Info("Database migrated.", "version", d.version)

	return nil
}

func (d *database) RegisterMigrations(moduleName string, fSys fs.FS) error {
	slog.Debug("Registering migrations for service.", "service", moduleName)

	if _, found := d.migrations[moduleName]; found {
		return fmt.Errorf(
			"%w: RegisterMigrations: module '%s': %w",
			core.ErrDatabase,
			moduleName,
			errMigrationsAlreadyRegistered,
		)
	}

	d.migrations[moduleName] = fSys

	slog.Debug("Migrations for service successfully registered.", "service", moduleName)

	return nil
}