package db

import (
	"errors"
	"fmt"

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

var (
	ErrNotInDB               = errors.New("not in db")
	ErrItemIsDeleted         = errors.New("item is deleted")
	ErrForeignKeyViolation   = errors.New("foreign key constraint failed")
	ErrDatabaseAlreadyExists = errors.New("target already exists")
)

type ForeignKey interface {
	~uint64 | ~string
}

type ForeignKeyError[T ForeignKey] struct {
	Field       string
	TargetTable string
	FkValue     T
}

func NewForeignKeyError[T ForeignKey](field, table string, fkValue T) ForeignKeyError[T] {
	return ForeignKeyError[T]{
		Field:       field,
		TargetTable: table,
		FkValue:     fkValue,
	}
}

func (e ForeignKeyError[T]) Error() string {
	return fmt.Sprintf(`%s: fk field %q (to %q) with value "%v"`,
		ErrForeignKeyViolation.Error(), e.Field, e.TargetTable, e.FkValue,
	)
}

// Unwrap returns the sentinel error-- permits the use of errors.Is for convenience
func (e ForeignKeyError[T]) Unwrap() error {
	return ErrForeignKeyViolation
}

// -------------
// SQLite errors
// -------------

// IsSqliteFkError checks whether an error is a SQLite foreign key constraint violation.
func IsSqliteFkError(err error) bool {
	var sqliteErr sqlite3.Error
	if !errors.As(err, &sqliteErr) {
		return false
	}
	return errors.Is(sqliteErr.ExtendedCode, sqlite3.ErrConstraintForeignKey)
}

// IsSqliteUniqError checks whether an error is a SQLite unique constraint violation.
func IsSqliteUniqError(err error) bool {
	var sqliteErr sqlite3.Error
	if !errors.As(err, &sqliteErr) {
		return false
	}
	return errors.Is(sqliteErr.ExtendedCode, sqlite3.ErrConstraintUnique)
}

// IsSqliteNotNullError checks whether an error is a SQLite not null constraint violation.
func IsSqliteNotNullError(err error) bool {
	var sqliteErr sqlite3.Error
	if !errors.As(err, &sqliteErr) {
		return false
	}
	return errors.Is(sqliteErr.ExtendedCode, sqlite3.ErrConstraintNotNull)
}