package util

import (
	"errors"
	"fmt"
)

// Code is a string error category used across the application.
type Code string

const (
	CodeBadRequest Code = "bad_request"
	CodeNotFound   Code = "not_found"
	CodeConflict   Code = "conflict"
	CodeInternal   Code = "internal"
)

// AppError is a typed error carrying a Code and optional wrapped error.
type AppError struct {
	Code    Code
	Message string
	Err     error
}

func (e *AppError) Error() string {
	if e.Err != nil {
		return fmt.Sprintf("%s: %s: %v", e.Code, e.Message, e.Err)
	}
	return fmt.Sprintf("%s: %s", e.Code, e.Message)
}

func (e *AppError) Unwrap() error {
	return e.Err
}

// New returns a new AppError with the given code and message.
func New(code Code, message string) error {
	return &AppError{Code: code, Message: message}
}

// Wrap returns a new AppError wrapping err with the given code and message.
func Wrap(code Code, message string, err error) error {
	return &AppError{Code: code, Message: message, Err: err}
}

// CodeOf returns the Code embedded in err. nil returns CodeInternal;
// non-AppError errors also default to CodeInternal.
func CodeOf(err error) Code {
	if err == nil {
		return CodeInternal
	}
	var ae *AppError
	if errors.As(err, &ae) {
		return ae.Code
	}
	return CodeInternal
}