package main

import (
	"bufio"
	"context"
	"encoding/json"
	"fmt"
	"io/fs"
	"net/http"
	"os"
	"os/exec"
	"strings"

	"hnyfkj.com.cn/rtu/linux/utils/jsonrpc2"
)

const noValue = "--"

type LoginReq struct {
	Username string `json:"username"`
	Password string `json:"password"`
}

type LoginResp struct {
	Success bool `json:"success"`
}

func loginHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}

	var req LoginReq
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		w.WriteHeader(http.StatusBadRequest)
		return
	}

	ok := req.Username == "admin" && req.Password == "admin123456"

	if ok {
		sessionID := createSession()
		addSession(sessionID)

		http.SetCookie(w, &http.Cookie{
			Name:     "session_id",
			Value:    sessionID,
			Path:     "/",
			HttpOnly: true,
			SameSite: http.SameSiteStrictMode,
		})
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(LoginResp{Success: ok})
}

func logoutHandler(w http.ResponseWriter, r *http.Request) {
	if cookie, err := r.Cookie("session_id"); err == nil {
		sessionMu.Lock()
		delete(sessions, cookie.Value)
		sessionMu.Unlock()
	}

	http.SetCookie(w, &http.Cookie{
		Name:   "session_id",
		Value:  "",
		Path:   "/",
		MaxAge: -1,
	})

	http.Redirect(w, r, "/", http.StatusFound)
}

func getIMEIHandler(w http.ResponseWriter, r *http.Request) {
	data, err := os.ReadFile("/var/device_imei.txt")
	if err != nil {
		w.Write([]byte(noValue))
	} else {
		w.Write(append([]byte("🆔"), data...))
	}
}

func sshdStatusHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}

	status := noValue
	cmd := exec.Command("systemctl", "is-active", "yfkj-sshd-mqtt-bridge.service")
	if out, err := cmd.Output(); err == nil {
		if strings.TrimSpace(string(out)) == "active" {
			status = "🟢 YFKJ-SSHD"
		}
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]string{"status": status})
}

func (ui *WebUI) rootHandler(w http.ResponseWriter, r *http.Request) {
	path := r.URL.Path

	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	w.Header().Set("Cache-Control", "no-store, no-cache, must-revalidate, max-age=0")
	w.Header().Set("Pragma", "no-cache")
	w.Header().Set("Expires", "0")

	// 1, 未登录时, 只能看登录页
	if !checkSession(r) {
		data, err := fs.ReadFile(ui.fs, "login.html")
		if err != nil {
			http.NotFound(w, r)
		} else {
			w.Write(data)
		}
		return
	}

	// 2, 登录成功, 展示应用首页
	if path == "/" {
		data, err := fs.ReadFile(ui.fs, "app.html")
		if err != nil {
			http.NotFound(w, r)
		} else {
			w.Write(data)
		}
		return
	}

	// 3, 在网站内跳转其它功能页
	if strings.HasPrefix(path, "/pages/") { // path 形如 "/pages/page1.html"
		data, err := fs.ReadFile(ui.fs, path[1:])
		if err != nil {
			http.NotFound(w, r)
		} else {
			w.Write(data)
		}
		return
	}

	// 4, 访问其它不认识的页面时
	http.NotFound(w, r)
}

func serviceLogHandler(w http.ResponseWriter, r *http.Request) {
	unit := r.URL.Query().Get("unit")
	if unit == "" {
		http.Error(w, "missing unit",
			http.StatusBadRequest)
		return
	}

	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("Connection", "keep-alive")
	w.Header().Set("X-Accel-Buffering", "no")

	flusher, ok := w.(http.Flusher)
	if !ok {
		http.Error(w, "not supported",
			http.StatusInternalServerError)
		return
	}

	cmd := exec.Command(
		"journalctl",
		"-f",
		"-u",
		unit,
		"-n",
		"10",
		"--no-pager",
		"-q",
		"-o",
		"short-iso",
	)

	stdout, err := cmd.StdoutPipe()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	if err := cmd.Start(); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	defer func() {
		if cmd.Process != nil {
			cmd.Process.Kill()
		}
		cmd.Wait()
	}()

	scanner := bufio.NewScanner(stdout)

	for scanner.Scan() {
		select {
		case <-r.Context().Done():
			return
		default:
		}

		if _, err := fmt.Fprintf(w, "data: %s\n\n", scanner.Text()); err != nil {
			return
		}

		flusher.Flush()
	}
}

func runShellAndWrite(w http.ResponseWriter, cmd string) {
	out, err := exec.Command("sh", "-c", cmd).CombinedOutput()
	if err != nil {
		http.Error(w, err.Error()+"\n"+string(out), http.StatusInternalServerError)
		return
	}
	w.Write(out)
}

func netInterfaces(w http.ResponseWriter, r *http.Request) {
	runShellAndWrite(w, "ifconfig")
}

func netRoutes(w http.ResponseWriter, r *http.Request) {
	runShellAndWrite(w, "route -n")
}

func netDNS(w http.ResponseWriter, r *http.Request) {
	runShellAndWrite(w, "cat /etc/resolv.conf")
}

func callRPCResult(ctx context.Context, port int, method string, params any, result any) error {
	client, err := jsonrpc2.NewRPCClient(fmt.Sprintf("http://127.0.0.1:%d/rpc", port))
	if err != nil {
		return err
	}

	resp, err := client.Call(ctx, method, params)
	if err != nil {
		return err
	}

	return json.Unmarshal(resp.Result, result)
}

func callRPCResponse(w http.ResponseWriter, r *http.Request, port int, method string, params any) {
	client, err := jsonrpc2.NewRPCClient(fmt.Sprintf("http://127.0.0.1:%d/rpc", port))
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	resp, err := client.Call(r.Context(), method, params)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	json.NewEncoder(w).Encode(resp.Result)
}

func serviceLogLevel(w http.ResponseWriter, r *http.Request, port int) {
	switch r.Method {
	case http.MethodGet:
		callRPCResponse(w, r, port, "basic.getLogLevel", nil)

	case http.MethodPost:
		var req struct {
			Level string `json:"level"`
		}

		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		callRPCResponse(w, r, port, "basic.setLogLevel", map[string]string{"log_level": req.Level})

	default:
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	}
}

func serviceLogLevelHandler(port int) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		serviceLogLevel(w, r, port)
	}
}