package middleware

import (
	"bufio"
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net"
	"net/http"
	"net/url"
	"strings"

	"github.com/zero-ppanel/zero-ppanel/apps/api/internal/config"
	"github.com/zero-ppanel/zero-ppanel/pkg/cryptox"
	"github.com/zero-ppanel/zero-ppanel/pkg/xerr"
	"github.com/zeromicro/go-zero/rest/httpx"
)

type DecryptMiddleware struct {
	conf config.Config
}

func NewDecryptMiddleware(c config.Config) *DecryptMiddleware {
	return &DecryptMiddleware{conf: c}
}

func (m *DecryptMiddleware) Handle(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		fmt.Printf("[DEBUG] DecryptMiddleware entered, Security.Enable=%v, Login-Type=%q\n",
			m.conf.Security.Enable, r.Header.Get("Login-Type"))
		if !m.conf.Security.Enable {
			next(w, r)
			return
		}

		if r.Header.Get("Login-Type") != "device" {
			next(w, r)
			return
		}

		secret := m.conf.Security.SecuritySecret
		rw := newEncryptResponseWriter(w, secret)

		// 解密 GET query
		query := r.URL.Query()
		dataStr := query.Get("data")
		timeStr := query.Get("time")
		if dataStr != "" && timeStr != "" {
			if plain, err := cryptox.Decrypt(dataStr, secret, timeStr); err == nil {
				params := map[string]interface{}{}
				if json.Unmarshal(plain, &params) == nil {
					for k, v := range params {
						query.Set(k, fmt.Sprintf("%v", v))
					}
					query.Del("data")
					query.Del("time")
					rawQuery := query.Encode()
					if strings.Contains(r.RequestURI, "?") {
						r.RequestURI = r.RequestURI[:strings.Index(r.RequestURI, "?")] + "?" + rawQuery
					}
					r.URL.RawQuery = rawQuery
				}
			}
		}

		// 解密 POST body
		if r.Body != nil {
			body, err := io.ReadAll(r.Body)
			if err != nil || len(body) == 0 {
				// body 为空或读取失败，直接放行
				r.Body = io.NopCloser(bytes.NewBuffer(body))
				next(rw, r)
				rw.flush()
				return
			}

			var envelope struct {
				Data string `json:"data"`
				Time string `json:"time"`
			}
			if err := json.Unmarshal(body, &envelope); err != nil || envelope.Data == "" {
				httpx.Error(w, xerr.NewErrCode(xerr.DecryptFailed))
				return
			}

			plain, err := cryptox.Decrypt(envelope.Data, secret, envelope.Time)
			if err != nil {
				httpx.Error(w, xerr.NewErrCode(xerr.DecryptFailed))
				return
			}
			fmt.Printf("[DEBUG] decrypted body: %s\n", string(plain))
			r.Body = io.NopCloser(bytes.NewBuffer(plain))
			// 防止 httpx.Parse 内部的 r.ParseForm() 消费已替换的 body：
			// ParseForm 首行检查 r.PostForm == nil，置空后它不会再读 body。
			r.PostForm = url.Values{}
			r.ContentLength = int64(len(plain))
		}

		next(rw, r)
		rw.flush()
	}
}

// encryptResponseWriter 拦截响应，加密 data 字段
type encryptResponseWriter struct {
	http.ResponseWriter
	body   *bytes.Buffer
	secret string
	status int
}

func newEncryptResponseWriter(w http.ResponseWriter, secret string) *encryptResponseWriter {
	return &encryptResponseWriter{
		ResponseWriter: w,
		body:           new(bytes.Buffer),
		secret:         secret,
		status:         http.StatusOK,
	}
}

func (rw *encryptResponseWriter) WriteHeader(code int) {
	rw.status = code
}

func (rw *encryptResponseWriter) Write(data []byte) (int, error) {
	return rw.body.Write(data)
}

func (rw *encryptResponseWriter) WriteString(s string) (int, error) {
	return rw.body.WriteString(s)
}

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

func (rw *encryptResponseWriter) flush() {
	buf := rw.body.Bytes()
	out := buf

	// 尝试加密 data 字段
	params := map[string]interface{}{}
	if err := json.Unmarshal(buf, &params); err == nil {
		if data := params["data"]; data != nil {
			var jsonData []byte
			if str, ok := data.(string); ok {
				jsonData = []byte(str)
			} else {
				jsonData, _ = json.Marshal(data)
			}
			if dataB64, nonce, err := cryptox.Encrypt(jsonData, rw.secret); err == nil {
				params["data"] = map[string]interface{}{
					"data": dataB64,
					"time": nonce,
				}
				if enc, err := json.Marshal(params); err == nil {
					out = enc
				}
			}
		}
	}

	rw.ResponseWriter.WriteHeader(rw.status)
	rw.ResponseWriter.Write(out)
}