package errors

import (
	"fmt"
	"sync"
)

type Coder interface {
	// HTTPStatus 返回http状态码
	HTTPStatus() int
	// String 展示给外部用户的错误信息
	String() string
	// Reference 展示给用户解决错误需要参开的引用文档
	Reference() string
	// Code 错误码
	Code() int
}

// 错误码映射
var codes = map[int]Coder{}
var codeMux = &sync.Mutex{}

// Register 注册错误码,存在会被覆盖
func Register(coder Coder) {
	if coder.Code() == 999999 {
		panic("code `999999` is reserved by system as unknownCode error code")
	}
	codeMux.Lock()
	defer codeMux.Unlock()

	codes[coder.Code()] = coder
}

// MustRegister 注册错误码,已注册报错
func MustRegister(coder Coder) {
	if coder.Code() == 999999 {
		panic("code `999999` is reserved by system as unknownCode error code")
	}

	codeMux.Lock()
	defer codeMux.Unlock()

	if _, ok := codes[coder.Code()]; ok {
		panic(fmt.Sprintf("code: %d already exist", coder.Code()))
	}

	codes[coder.Code()] = coder
}

// ParseCoder 解析错误码
// 将错误解析为 *withCode 类型。如果原生错误不是本错误包生成，返回未知错误
func ParseCoder(err error) Coder {
	if err == nil {
		return nil
	}

	if v, ok := err.(*withCode); ok {
		if coder, ok := codes[v.code]; ok {
			return coder
		}
	}

	return unknownCoder
}

// IsCode 判断错误码是否在当前错误链中
func IsCode(err error, code int) bool {
	if v, ok := err.(*withCode); ok {
		if v.code == code {
			return true
		}

		if v.cause != nil {
			return IsCode(v.cause, code)
		}

		return false
	}

	return false
}