package sql

import (
	"fmt"
	log "github.com/Sirupsen/logrus"
	"github.com/go-gorp/gorp/v3"
	"regexp"
	"time"
)

var (
	autoIncrementRE = regexp.MustCompile(`(?i)\bautoincrement\b`)
	serialRE = regexp.MustCompile(`(?i)\binteger primary key autoincrement\b`)
	dateTimeTypeRE = regexp.MustCompile(`(?i)\bdatetime\b`)
	tinyintRE = regexp.MustCompile(`(?i)\btinyint\b`)
	longtextRE = regexp.MustCompile(`(?i)\blongtext\b`)
	ifExistsRE = regexp.MustCompile(`(?i)\bif exists\b`)
	dropForeignKey = regexp.MustCompile(`(?i)\bdrop foreign key\b`)
)

// prepareMigration converts migration SQLite-query to current dialect.
// Supported MySQL and Postgres dialects.
func (d *SqlDb) prepareMigration(query string) string {
	switch d.sql.Dialect.(type) {
	case gorp.MySQLDialect:
		query = autoIncrementRE.ReplaceAllString(query, "auto_increment")
		query = ifExistsRE.ReplaceAllString(query, "")
	case gorp.PostgresDialect:
		query = serialRE.ReplaceAllString(query, "serial primary key")
		query = identifierQuoteRE.ReplaceAllString(query, "\"")
		query = dateTimeTypeRE.ReplaceAllString(query, "timestamp")
		query = tinyintRE.ReplaceAllString(query, "smallint")
		query = longtextRE.ReplaceAllString(query, "text")
		query = dropForeignKey.ReplaceAllString(query, "drop constraint")
	}
	return query
}

// isMigrationApplied queries the database to see if a migration table with this version id exists already
func (d *SqlDb) isMigrationApplied(version *Version) (bool, error) {
	exists, err := d.sql.SelectInt(d.prepareQuery("select count(1) as ex from migrations where version=?"), version.VersionString())

	if err != nil {
		fmt.Println("Creating migrations table")
		query := d.prepareMigration(initialSQL)
		if _, err = d.exec(query); err != nil {
			panic(err)
		}

		return d.isMigrationApplied(version)
	}

	return exists > 0, nil
}

// Run executes a database migration
func (d *SqlDb) applyMigration(version *Version) error {
	fmt.Printf("Executing migration %s (at %v)...\n", version.HumanoidVersion(), time.Now())

	tx, err := d.sql.Begin()
	if err != nil {
		return err
	}

	query := version.GetSQL(version.GetPath())
	for i, query := range query {
		fmt.Printf("\r [%d/%d]", i+1, len(query))

		if len(query) == 0 {
			continue
		}

		q := d.prepareMigration(query)
		_, err = tx.Exec(q)
		if err != nil {
			handleRollbackError(tx.Rollback())
			log.Warnf("\n ERR! Query: %v\n\n", q)
			return err
		}
	}

	if _, err := tx.Exec(d.prepareQuery("insert into migrations(version, upgraded_date) values (?, ?)"), version.VersionString(), time.Now()); err != nil {
		handleRollbackError(tx.Rollback())
		return err
	}

	fmt.Println()

	return tx.Commit()
}

// TryRollback attempts to rollback the database to an earlier version if a rollback exists
func (d *SqlDb) tryRollbackMigration(version *Version) {
	fmt.Printf("Rolling back %s (time: %v)...\n", version.HumanoidVersion(), time.Now())

	data := dbAssets.Bytes(version.GetErrPath())
	if len(data) == 0 {
		fmt.Println("Rollback SQL does not exist.")
		fmt.Println()
		return
	}

	query := version.GetSQL(version.GetErrPath())
	for _, query := range query {
		fmt.Printf(" [ROLLBACK] > %v\n", query)

		if _, err := d.exec(d.prepareMigration(query)); err != nil {
			fmt.Println(" [ROLLBACK] - Stopping")
			return
		}
	}
}

func (d *SqlDb) Migrate() error {
	fmt.Println("Checking DB migrations")
	didRun := false

	// go from beginning to the end
	for _, version := range Versions {
		if exists, err := d.isMigrationApplied(version); err != nil || exists {
			if exists {
				continue
			}

			return err
		}

		didRun = true
		if err := d.applyMigration(version); err != nil {
			d.tryRollbackMigration(version)

			return err
		}
	}

	if didRun {
		fmt.Println("Migrations Finished")
	}

	return nil
}