package middleware

import (
	"bufio"
	"bytes"
	"io"
	"io/ioutil"
	"net"
	"net/http"

	"github.com/labstack/echo/v4"
)

type (
	// BodyDumpConfig defines the config for BodyDump middleware. 
	BodyDumpConfig struct {
		// Skipper defines a function to skip middleware. 
		Skipper Skipper

		// Handler receives request and response payload. 
		// Required. 
		Handler BodyDumpHandler
	}

	// BodyDumpHandler receives the request and response payload. 
	BodyDumpHandler func(echo. Context, []byte, []byte)

	bodyDumpResponseWriter struct {
		io. Writer
		http. ResponseWriter
	}
)

var (
	// DefaultBodyDumpConfig is the default BodyDump middleware config. 
	DefaultBodyDumpConfig = BodyDumpConfig{
		Skipper: DefaultSkipper,
	}
)

// BodyDump returns a BodyDump middleware. 
//
// BodyDump middleware captures the request and response payload and calls the
// registered handler. 
func BodyDump(handler BodyDumpHandler) echo. MiddlewareFunc {
	c := DefaultBodyDumpConfig
	c.Handler = handler
	return BodyDumpWithConfig(c)
}

// BodyDumpWithConfig returns a BodyDump middleware with config. 
// See: `BodyDump()`. 
func BodyDumpWithConfig(config BodyDumpConfig) echo. MiddlewareFunc {
	// Defaults
	if config. Handler == nil {
		panic("echo: body-dump middleware requires a handler function")
	}
	if config. Skipper == nil {
		config. Skipper = DefaultBodyDumpConfig. Skipper
	}

	return func(next echo. HandlerFunc) echo. HandlerFunc {
		return func(c echo. Context) (err error) {
			if config. Skipper(c) {
				return next(c)
			}

			// Request
			reqBody := []byte{}
			if c.Request().Body ! = nil { // Read
				reqBody, _ = ioutil. ReadAll(c. Request().Body)
			}
			c.Request().Body = ioutil. NopCloser(bytes. NewBuffer(reqBody)) // Reset

			// Response
			resBody := new(bytes. Buffer)
			mw := io. MultiWriter(c. Response().Writer, resBody)
			writer := &bodyDumpResponseWriter{Writer: mw, ResponseWriter: c.Response().Writer}
			c.Response().Writer = writer

			if err = next(c); err ! = nil {
				c.Error(err)
			}

			// Callback
			config. Handler(c, reqBody, resBody. Bytes())

			return
		}
	}
}

func (w *bodyDumpResponseWriter) WriteHeader(code int) {
	w.ResponseWriter. WriteHeader(code)
}

func (w *bodyDumpResponseWriter) Write(b []byte) (int, error) {
	return w.Writer. Write(b)
}

func (w *bodyDumpResponseWriter) Flush() {
	w.ResponseWriter.(http. Flusher).Flush()
}

func (w *bodyDumpResponseWriter) Hijack() (net. Conn, *bufio. ReadWriter, error) {
	return w.ResponseWriter.(http. Hijacker).Hijack()
}
