package model

import (
	"database/sql"
	"log"

	_ "github.com/mattn/go-sqlite3"

	"xengineering.eu/ceres/model/migrations"
)

type DB sql.DB

func OpenDB(path string) *DB {
	db, err := sql.Open("sqlite3", path)
	if err != nil {
		log.Fatal(err)
	}

	err = db.Ping()
	if err != nil {
		log.Fatal(err)
	}

	return (*DB)(db)
}

func (db *DB) Transaction(f func(*sql.Tx) error) error {
	tx, err := (*sql.DB)(db).Begin()
	if err != nil {
		log.Printf("Failed to start database transaction: %v", err)
		return err
	}
	defer func() {
		if tx.Rollback() == nil {
			log.Println("Rolled back transaction")
		}
	}()

	err = f(tx)
	if err != nil {
		log.Printf("Failed transaction: %v", err)
		return err
	}

	return tx.Commit()
}

func (db *DB) IsEmpty() bool {
	var number int

	_ = db.Transaction(func(tx *sql.Tx) error {
		cmd := `SELECT COUNT(*) FROM sqlite_master WHERE type='table'`
		rows, err := tx.Query(cmd)
		if err != nil {
			log.Fatal(err)
		}
		defer rows.Close()

		if !rows.Next() {
			log.Fatalf("No rows on request of database table number")
		}

		err = rows.Scan(&number)
		if err != nil {
			log.Fatalf("Failed to scan number of database tables to integer")
		}

		return nil
	})

	return number == 0
}

func (db *DB) setupMinimal(execVersion string) error {
	return db.Transaction(func(tx *sql.Tx) error {
		cmd := `
CREATE TABLE metadata (
	key   TEXT PRIMARY KEY,
	value TEXT
);
INSERT INTO metadata
	(key, value)
VALUES
	('version', ?);
`
		_, err := tx.Exec(cmd, execVersion)
		return err
	})
}

func (db *DB) Version() string {
	var version string

	_ = db.Transaction(func(tx *sql.Tx) error {
		rows, err := tx.Query(`SELECT value FROM metadata WHERE key='version';`)
		if err != nil {
			log.Fatal(err)
		}
		defer rows.Close()

		if !rows.Next() {
			log.Fatalf("No rows on request of database version")
		}

		err = rows.Scan(&version)
		if err != nil {
			log.Fatalf("Failed to scan database version to string")
		}

		return nil
	})

	return version
}

func (db *DB) Migrate(execVersion string) {
	err := db.Transaction(func(tx *sql.Tx) error {
		if db.IsEmpty() {
			log.Println("Starting with empty database")
			err := db.setupMinimal(execVersion)
			if err != nil {
				log.Fatalf("Failed to setup minimal database schema: %v", err)
			}

			log.Println("Executing initial migration")
			err = migrations.Migration001(tx)
			if err != nil {
				return err
			}
		}

		dbVersion := db.Version()
		if dbVersion != execVersion {
			log.Fatalf(
				"Database version '%s' does not match executable version '%s'",
				dbVersion,
				execVersion,
			)
		}

		return nil
	})
	if err != nil {
		log.Fatalf("Fatal: Database migration failed")
	}
}

func (db *DB) CreateExamples() {
	err := db.Transaction(func(tx *sql.Tx) error {
		recipes := RecipeTestData()

		for _, recipe := range recipes {
			err := recipe.Create(tx)
			if err != nil {
				return err
			}
		}

		return nil
	})
	if err != nil {
		log.Fatalf("Failed to inject example recipes: %v", err)
	}
}

func (db *DB) Close() {
	err := (*sql.DB)(db).Close()
	if err != nil {
		log.Printf("Failed to close database: %v\n", err)
	} else {
		log.Println("Closed database")
	}
}