package db

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

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

var (
	// 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
)

var (
	ErrTargetExists = errors.New("target already exists")
)

// Colors for terminal output
const (
	ColorReset  = "\033[0m"
	ColorBlack  = "\033[30m"
	ColorRed    = "\033[31m"
	ColorGreen  = "\033[32m"
	ColorYellow = "\033[33m"
	ColorBlue   = "\033[34m"
	ColorPurple = "\033[35m"
	ColorCyan   = "\033[36m"
	ColorGray   = "\033[37m"
	ColorWhite  = "\033[97m"
)

func Init(schema *string, migrationsList *[]string) {
	sql_schema = schema
	migrations = migrationsList
	version_number = uint(len(*migrations))
	is_initialized = true
}

func Create(path string) (*sqlx.DB, error) {
	// First check if the path already exists
	_, err := os.Stat(path)
	if err == nil {
		return nil, ErrTargetExists
	} 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 := sqlx.MustOpen("sqlite3", path+"?_foreign_keys=on&_journal_mode=WAL")
	db.MustExec(*sql_schema)

	return db, nil
}

func Connect(path string) (*sqlx.DB, error) {
	db := sqlx.MustOpen("sqlite3", fmt.Sprintf("%s?_foreign_keys=on&_journal_mode=WAL", path))
	err := CheckAndUpdateVersion(db)
	return db, err
}

func 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 > version_number {
		return VersionMismatchError{version_number, version}
	}

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		fmt.Printf("Database version is out of date.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

	return nil
}

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

		db.MustExec((*migrations)[i])
		db.MustExec("update db_version set version = ?", i+1)

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