package leego

import (
	"fmt"
	"io"
	"net/http"
	"strings"
)

var (
	GowayTracer = http.CanonicalHeaderKey("Goway-Tracer")
	GowayServer = http.CanonicalHeaderKey("Goway-Server")
)

type OptionGoway struct {
	// 环境 (必选)
	Env string
	// 应用 ID (必选)
	AppId string
	// 应用版本 (可选)
	AppVer string
	// 实例 ID (可选)
	InstanceId string
}

// RequestByGoway 尝试通过 Goway 网关发起请求
func (own *Context) RequestByGoway(method, url string, headers map[string]string, optGoway OptionGoway, body io.Reader) (*http.Response, error) {
	if optGoway.Env == "" || optGoway.AppId == "" {
		return nil, fmt.Errorf("nil goway gateway")
	}

	var server string
	if optGoway.AppVer == "" {
		if optGoway.InstanceId != "" {
			server = fmt.Sprintf("%s, %s, %s, %s", optGoway.Env, optGoway.AppId, optGoway.AppVer, optGoway.InstanceId)
		} else {
			server = fmt.Sprintf("%s, %s, %s", optGoway.Env, optGoway.AppId, optGoway.AppVer)
		}
	} else {
		server = fmt.Sprintf("%s, %s", optGoway.Env, optGoway.AppId)
	}

	req, err := http.NewRequest(method, url, body)
	if err != nil {
		return nil, err
	}

	for key, val := range headers {
		req.Header.Set(key, val)
	}
	req.Header.Set(GowayServer, server)
	req.Header.Set(GowayTracer, own.Headers.Get(GowayTracer))

	return http.DefaultClient.Do(req)
}

// GetGowayTracer 尝试获取 Goway 网关中的的链路 ID：trace id 和 span id
func (own *Context) GetGowayTracer() (tid, sid string) {
	info := strings.Split(own.Headers.Get(GowayTracer), ", ")
	if len(info) == 1 {
		return info[0], ""
	}

	if len(info) > 1 {
		return info[0], info[1]
	}
	return
}

// GetGowayServer 尝试获取 Goway 网关的代理数据：env, app id, app ver, instance id
func (own *Context) GetGowayServer() (env, appId, appVer, instanceId string) {
	info := strings.Split(own.Headers.Get(GowayServer), ", ")
	switch len(info) {
	case 0: // 未指定任何信息
		return
	case 1: // 只指定环境
		env = info[0]
	case 2: // 指定应用环境和ID
		env = info[0]
		appId = info[1]
	case 3: // 指定应用环境、ID和版本
		env = info[0]
		appId = info[1]
		appVer = info[2]
	default: // 指定应用环境、ID、版本和实例ID
		env = info[0]
		appId = info[1]
		appVer = info[2]
		instanceId = info[3]
	}
	return
}