api/api.go

package api

import (
	"fmt"
	"reflect"

	"github.com/gin-gonic/gin"
	"github.com/go-playground/validator/v10"
	"qoobing.com/gomod/log"
	"qoobing.com/gomod/str"
)

var (
	validate              = validator.New()
	requestLogidGetter    = defaultLogidGetter
	requestHandlerMapper  = map[string]gin.HandlerFunc{}
	errCodeUnknownError   = -10000
	errCodeParameterError = -20000
	errCodeUnimplementApi = -20401
)

type Engine struct {
	*gin.Engine
}

type BaseWithEnoOutput struct {
	Eno int    `json:"eno"`
	Err string `json:"err"`
}

type BaseWithCodeOutput struct {
	Code int    `json:"code"`
	Msg  string `json:"msg"`
}

type BaseWithErrCodeOutput struct {
	ErrCode int    `json:"errCode"`
	ErrMsg  string `json:"errMsg"`
}

func NewEngine(pre ...gin.HandlerFunc) *Engine {
	gin.SetMode(gin.ReleaseMode)
	e := gin.New()
	for _, m := range pre {
		e.Use(m)
	}
	e.Use(middlewareMyApiEngine())
	return &Engine{e}
}

func (e *Engine) POST(uri string, handler Handler) {
	h := handlerWrapper(handler)
	log.Infof("api handler [%v] registor success", handler)
	e.Engine.POST(uri, h)
}

// handlerWrapper
func handlerWrapper(handler Handler) gin.HandlerFunc {
	handlerFunc := handler.HandlerFunc()
	wrappedHandlerFunc := func(c *gin.Context) {
		// Case 1. get request handler
		if c.Request == nil && c.Keys != nil {
			c.Keys["handler"] = handler
			return
		}

		// Case 2. normal case, user request will go this way
		if icc, ok := c.Get("cc"); !ok {
			log.Errorf("Unreachable Code: can not get cc(*api.Context) from *gin.Context")
		} else if cc, ok := icc.(*Context); !ok {
			log.Debugf("Unreachable Code: cc from *gin.Context is type of:[%s]", reflect.TypeOf(icc).String())
			log.Errorf("Unreachable Code: cc from *gin.Context is not type of *api.Context")
		} else {
			// user request should go this way
			defer cc.TryRecover()
			cc.AppId = c.GetString("appid")
			cc.UserId = c.GetUint64("userid")
			handlerFunc(cc)
			return
		}
	}
	hkey := fmt.Sprintf("%v", wrappedHandlerFunc)
	requestHandlerMapper[hkey] = wrappedHandlerFunc
	return wrappedHandlerFunc
}

// handlerWrapper
func handlerFuncWrapper(handler HandlerFunc) gin.HandlerFunc {
	return func(c *gin.Context) {
		if icc, ok := c.Get("cc"); !ok {
			log.Errorf("Unreachable Code: can not get cc(*api.Context) from *gin.Context")
		} else if cc, ok := icc.(*Context); !ok {
			log.Debugf("Unreachable Code: cc from *gin.Context is type of:[%s]", reflect.TypeOf(icc).String())
			log.Errorf("Unreachable Code: cc from *gin.Context is not type of *api.Context")
		} else {
			defer cc.TryRecover()
			cc.AppId = c.GetString("appid")
			cc.UserId = c.GetUint64("userid")
			handler(cc)
			return
		}
	}
}

// middlewareMyApiEngine myapi engine middleware
func middlewareMyApiEngine() gin.HandlerFunc {
	return func(c *gin.Context) {
		// Step 1. set logid
		id := requestLogidGetter(c)
		log.SetLogid(id)
		defer log.Cleanup()

		// Step 2. init *api.Context
		req := c.Request
		log.DebugfWithDepth(1, "[%s|%s|%s]", req.Method, req.Host, req.RequestURI)
		cc := New(c)
		c.Set("cc", cc)

		// Step 3. do request
		c.Next()

		// Step 4. recorde metrics
		cc.recordMetrics()
	}
}

// defaultLogidGetter get logid from "X-Request-Id" or create a new one.
func defaultLogidGetter(c *gin.Context) (logid string) {
	if logid = c.Request.Header.Get("X-Request-Id"); logid != "" {
		return logid
	}
	if logid = str.GetRandomNumString(13); logid != "" {
		return logid
	}
	panic("unreachable code")
}

func CC(c *gin.Context) *Context {
	if icc, ok := c.Get("cc"); !ok {
		log.Errorf("Unreachable Code: can not get cc(*api.Context) from *gin.Context")
	} else if cc, ok := icc.(*Context); !ok {
		log.Debugf("Unreachable Code: cc from *gin.Context is type of:[%s]", reflect.TypeOf(icc).String())
		log.Errorf("Unreachable Code: cc from *gin.Context is not type of *api.Context")
	} else {
		return cc
	}
	return nil
}

func ApiHandler(c *gin.Context) Handler {
	h := c.Handler()
	hkey := fmt.Sprintf("%v", h)
	if _, ok := requestHandlerMapper[hkey]; !ok {
		return nil
	}

	newc := &gin.Context{
		Request: nil,
		Keys:    map[string]any{},
	}
	h(newc)
	return newc.Keys["handler"].(Handler)
}

func RecordMetrics(api, errcode, appid string, costms float64) {
	var (
		counter = metricApiCounter.WithLabelValues(api, errcode, appid)
		summary = metricApiSummary.WithLabelValues(api, errcode, appid)
	)
	// Metric 1. api request counter
	counter.Inc()
	// Metric 2. api request cost/latency
	summary.Observe(costms)
}

func DumpHandlerFunc(c *Context) error {
	errmsg := "api not implemented"
	errcode := errCodeUnimplementApi
	return c.RESULT_ERROR(errcode, errmsg)
}

func ErrorHandler(c *gin.Context, errcode int, errmsg string) {
	handler := handlerFuncWrapper(func(c *Context) error {
		return c.RESULT_ERROR(errcode, errmsg)
	})
	handler(c)
}

func InitErrCodes(errcodes map[string]int) {
	if code, ok := errcodes["ErrCodeUnknownError"]; ok {
		errCodeUnknownError = code
	}
	if code, ok := errcodes["ErrCodeUnimplementApi"]; ok {
		errCodeUnknownError = code
	}
	if code, ok := errcodes["errCodeParameterError"]; ok {
		errCodeParameterError = code
	}
}