api/context.go

package api

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"reflect"
	"runtime/debug"
	"strconv"
	"strings"
	"time"

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

type Context struct {
	*gin.Context
	e *gin.Engine

	AppId  string //current request appid, must not be empty
	UserId uint64 //current request userid, maybe 0 if user unknown

	resultentry string
	httpstatus  int
	starttime   time.Time
	output      interface{}
	errcode     int
}

func New(c *gin.Context) *Context {
	return &Context{
		Context:    c,
		httpstatus: 200,
		starttime:  time.Now(),
		AppId:      "",
		UserId:     0,
	}
}

func (c *Context) TryRecover() {
	if err := recover(); err != nil {
		calldepth := 3
		stack := strings.Replace(string(debug.Stack()), "\n", "\n==    ", -1)
		stack = str.SkipLine(stack, calldepth*2+1)

		t := reflect.TypeOf(err)
		switch t.Kind() {
		case reflect.String:
			log.Fatalf("panic err:%v. Panic stack:\n%s", err, stack)
			c.RESULT_ERROR(errCodeUnknownError, "unknown error")
		default:
			log.Fatalf("panic err type: %s:%s. Panic stack:\n%s", t.Name(), t.String(), stack)
			c.RESULT_ERROR(errCodeUnknownError, "unknown error")
		}
	}
}

func (c *Context) BindInput(i interface{}) (err error) {
	logstr := fmt.Sprintf("input:[have not initialized]")
	defer func(plogstr *string) {
		log.DebugfWithDepth(2, "%s", *plogstr)
	}(&logstr)

	err = c.ShouldBind(i)
	if err != nil {
		b, _ := json.Marshal(i)
		logstr = fmt.Sprintf("input:%s binderror:%s", string(b), err.Error())
		return err
	}

	err = validate.Struct(i)
	if err != nil {
		outputstr := ""
		for _, err := range err.(validator.ValidationErrors) {
			b, _ := json.Marshal(i)
			logstr = fmt.Sprintf("input:%s validateerror:%s", string(b), err.Error())
			outputstr = fmt.Sprintf("invalide field: [%s(%s)]", err.Field(), err.Tag())
			return errors.New(outputstr)
		}
		panic("Unreachable Code")
	}

	// recode input parameters.
	b, _ := json.Marshal(i)
	logstr = fmt.Sprintf("input:%s", string(b))
	return nil
}

func (c *Context) BindOutput(o interface{}) (err error) {
	var v = reflect.ValueOf(o)
	if v.Kind() != reflect.Pointer {
		return fmt.Errorf("output is NOT a pointer")
	}

	var e = v.Elem()
	var t = e.Type()
	if _, ok := t.FieldByName("ErrCode"); !ok {
		return fmt.Errorf("out have no field ErrCode")
	}
	if _, ok := t.FieldByName("ErrMsg"); !ok {
		return fmt.Errorf("out have no field ErrMsg")
	}
	if code := e.FieldByName("ErrCode"); !code.CanSet() {
		return fmt.Errorf("output.ErrCode can not be set, " +
			"output is NOT a pointer or output have no field 'ErrCode'")
	}

	c.output = o
	return nil
}

func (c *Context) SetCookie(cookie *http.Cookie) {
	if cookie.Path == "" {
		cookie.Path = "/"
	}
	http.SetCookie(c.Writer, cookie)
}

func (c *Context) RESULT(output interface{}) error {
	var t = reflect.TypeOf(output)
	defer func(o *interface{}) {
		b, err := json.Marshal(o)
		if err != nil {
			return
		}
		calldepth := 0
		switch c.resultentry {
		case "RESULT":
			calldepth = 0
		case "RESULT_ERROR":
			calldepth = 1
		case "RESULT_PARAMETER_ERROR":
			calldepth = 2
		}
		//// cut log if too long ////// begin //////////////
		if len(b) > 1024 {
			//no := retag.Convert(*o, retag.NewView("json", "!logignore"))
			//if nb, err := json.Marshal(no); err != nil {
			//    return
			//} else {
			//    b = nb
			//}
		}
		//// cut log if too long ////// end ////////////////
		cost := time.Now().Sub(c.starttime).Milliseconds()
		noticeStr := fmt.Sprintf("cost: %dms, output: '%s'", cost, string(b))
		log.NoticefWithDepth(calldepth, noticeStr)

		//////// metrics //////////////////////////////////
		c.recordMetrics()
	}(&output)

	if _, ok := t.FieldByName("ErrCode"); !ok {
		errstr := "Result MUST have 'ErrCode' field"
		output = BaseWithErrCodeOutput{errCodeUnknownError, errstr}
		c.shapeOutput(output)
		c.errcode = int(reflect.ValueOf(output).FieldByName("ErrCode").Int())
		c.IndentedJSON(c.httpstatus, output)
		return errors.New(errstr)
	}

	if _, ok := t.FieldByName("ErrMsg"); !ok {
		errstr := "Result MUST have 'ErrMsg' field"
		output = BaseWithErrCodeOutput{errCodeUnknownError, errstr}
		c.shapeOutput(output)
		c.errcode = int(reflect.ValueOf(output).FieldByName("ErrCode").Int())
		c.IndentedJSON(c.httpstatus, output)
		return errors.New(errstr)
	}

	c.shapeOutput(output)
	c.errcode = int(reflect.ValueOf(output).FieldByName("ErrCode").Int())
	c.IndentedJSON(c.httpstatus, output)
	return nil
}

func (c *Context) RESULT_ERROR(eno int, err string) error {
	if c.resultentry == "" {
		c.resultentry = "RESULT_ERROR"
	}

	result := BaseWithErrCodeOutput{eno, err}
	c.errcode = eno
	return c.RESULT(result)
}

func (c *Context) RESULT_PARAMETER_ERROR(err string) error {
	if c.resultentry == "" {
		c.resultentry = "RESULT_PARAMETER_ERROR"
	}
	return c.RESULT_ERROR(errCodeParameterError, err)
}

func (c *Context) ApiHandler() Handler {
	return ApiHandler(c.Context)
}

func (c *Context) shapeOutput(o interface{}) {
	if c.output == nil {
		return
	}

	var out, ok = o.(BaseWithErrCodeOutput)
	if !ok {
		return
	}

	var e = reflect.ValueOf(c.output).Elem()
	e.FieldByName("ErrMsg").SetString(out.ErrMsg)
	e.FieldByName("ErrCode").SetInt(int64(out.ErrCode))
	return
}

func (c *Context) recordMetrics() {
	if metricApiCounter == nil ||
		metricApiSummary == nil {
		return
	}
	var (
		h       = c.ApiHandler()
		api     = h.ApiName()
		appid   = c.AppId
		costus  = time.Now().Sub(c.starttime).Microseconds()
		costms  = float64(costus) / 1000.0
		errcode = strconv.Itoa(c.errcode)
	)
	RecordMetrics(api, errcode, appid, costms)
}