package db

import (
	_ "embed"
	"errors"
	"fmt"
	"os"

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

	"git.offline-twitter.com/offline-labs/gas-stack/pkg/textutils"
)

type DBConfig struct {
	// // Tracks whether the DB connector has been initialized
	// is_initialized bool

	// The SQL schema of the database under management
	sql_schema *string

	// Database starts at version 0.  First migration brings us to version 1
	migrations     *[]string
	version_number uint
}

func Init(schema *string, migrationsList *[]string) DBConfig {
	return DBConfig{
		sql_schema:     schema,
		migrations:     migrationsList,
		version_number: uint(len(*migrationsList)),
	}
}

func (c DBConfig) Create(path string) (*sqlx.DB, error) {
	// First check if the path already exists
	_, err := os.Stat(path)
	if err == nil {
		return nil, ErrDatabaseAlreadyExists
	} else if !errors.Is(err, os.ErrNotExist) {
		return nil, fmt.Errorf("path error: %w", err)
	}

	// Create DB file
	fmt.Printf("Creating.............   %s\n", path)
	db, err := sqlx.Open("sqlite3", path)
	if err != nil {
		return nil, fmt.Errorf("opening db: %w", err)
	}

	// Initialize schema
	if _, err = db.Exec("pragma foreign_keys=on; pragma journal_mode=WAL;"); err != nil {
		return nil, fmt.Errorf("running pragma statements: %w", err)
	}
	if _, err = db.Exec(*c.sql_schema); err != nil {
		return nil, fmt.Errorf("creating schema: %w", err)
	}

	return db, nil
}

func (c DBConfig) Connect(path string) (*sqlx.DB, error) {
	db, err := sqlx.Open("sqlite3", path)
	if err != nil {
		return nil, fmt.Errorf("opening db: %w", err)
	}
	if _, err = db.Exec("pragma foreign_keys=on; pragma journal_mode=WAL;"); err != nil {
		return nil, fmt.Errorf("running pragma statements: %w", err)
	}

	err = c.CheckAndUpdateVersion(db)
	return db, err
}

func (c DBConfig) CheckAndUpdateVersion(db *sqlx.DB) error {
	var version uint
	err := db.Get(&version, "select version from db_version")
	if err != nil {
		return fmt.Errorf("couldn't check database version: %w", err)
	}

	if version > c.version_number {
		return VersionMismatchError{c.version_number, version}
	}

	if c.version_number > version {
		fmt.Print(textutils.ColorYellow)
		fmt.Printf("================================================\n")
		fmt.Printf("Database version is out of date.  Upgrading database from version %d to version %d!\n", version,
			c.version_number)
		fmt.Print(textutils.ColorReset)
		c.UpgradeFromXToY(db, version, c.version_number)
	}

	return nil
}

// UpgradeFromXToY runs all the migrations from version X to version Y, and update the `database_version` table's `version_number`
func (c DBConfig) UpgradeFromXToY(db *sqlx.DB, x uint, y uint) {
	for i := x; i < y; i++ {
		fmt.Print(textutils.ColorCyan)
		fmt.Println((*c.migrations)[i])
		fmt.Print(textutils.ColorReset)

		// Execute the migration in a transaction
		tx, err := db.Beginx()
		if err != nil {
			panic(err)
		}
		tx.MustExec((*c.migrations)[i])
		tx.MustExec("update db_version set version = ?", i+1)
		if err := tx.Commit(); err != nil {
			panic(err)
		}

		fmt.Print(textutils.ColorYellow)
		fmt.Printf("Now at database schema version %d.\n", i+1)
		fmt.Print(textutils.ColorReset)
	}
	fmt.Print(textutils.ColorGreen)
	fmt.Printf("================================================\n")
	fmt.Printf("Database version has been upgraded to version %d.\n", y)
	fmt.Print(textutils.ColorReset)
}

type VersionMismatchError struct {
	EngineVersion   uint
	DatabaseVersion uint
}

func (e VersionMismatchError) Error() string {
	return fmt.Sprintf(
		`This profile was created with database schema version %d, which is newer than this application's database schema version, %d.
Please upgrade this application to a newer version to use this profile.  Or downgrade the profile's schema version, somehow.`,
		e.DatabaseVersion, e.EngineVersion,
	)
}