package controllers

import (
	"bufio"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"runtime"
	"sync"
	"unicode/utf8"

	"baihu/internal/constant"
	"baihu/internal/utils"

	"github.com/creack/pty"
	"github.com/gin-gonic/gin"
	"github.com/gorilla/websocket"
	"golang.org/x/text/encoding/simplifiedchinese"
	"golang.org/x/text/transform"
)

type TerminalController struct{}

func NewTerminalController() *TerminalController {
	return &TerminalController{}
}

var upgrader = websocket.Upgrader{
	CheckOrigin: func(r *http.Request) bool {
		return true
	},
}

// toUTF8 将可能是 GBK 编码的字节转换为 UTF-8
func toUTF8(data []byte) string {
	if utf8.Valid(data) {
		return string(data)
	}
	// 尝试从 GBK 转换
	reader := transform.NewReader(
		bufio.NewReader(
			&byteReader{data: data},
		),
		simplifiedchinese.GBK.NewDecoder(),
	)
	result, err := io.ReadAll(reader)
	if err != nil {
		return string(data)
	}
	return string(result)
}

type byteReader struct {
	data []byte
	pos  int
}

func (r *byteReader) Read(p []byte) (n int, err error) {
	if r.pos >= len(r.data) {
		return 0, io.EOF
	}
	n = copy(p, r.data[r.pos:])
	r.pos += n
	return n, nil
}

func (tc *TerminalController) HandleWebSocket(c *gin.Context) {
	conn, err := upgrader.Upgrade(c.Writer, c.Request, nil)
	if err != nil {
		return
	}
	defer conn.Close()

	// Windows 使用 pipe 模式，Unix 使用 PTY 模式
	if runtime.GOOS == "windows" {
		tc.handlePipeMode(conn)
	} else {
		tc.handlePtyMode(conn)
	}
}

// handlePtyMode 使用 PTY 处理终端（Unix/macOS）
func (tc *TerminalController) handlePtyMode(conn *websocket.Conn) {
	// 发送 PTY 模式标识
	conn.WriteMessage(websocket.TextMessage, []byte("__PTY_MODE__"))

	cmd := utils.NewShellCmd()

	if absDir, err := filepath.Abs(constant.ScriptsWorkDir); err == nil {
		cmd.Dir = absDir
	}

	cmd.Env = append(os.Environ(), "TERM=xterm-256color")

	ptmx, err := pty.Start(cmd)
	if err != nil {
		conn.WriteMessage(websocket.TextMessage, []byte("Error starting shell: "+err.Error()))
		return
	}
	defer ptmx.Close()

	pty.Setsize(ptmx, &pty.Winsize{Rows: 24, Cols: 80})

	var wg sync.WaitGroup
	var connMu sync.Mutex

	writeMessage := func(data []byte) {
		connMu.Lock()
		defer connMu.Unlock()
		conn.WriteMessage(websocket.TextMessage, data)
	}

	wg.Add(1)
	go func() {
		defer wg.Done()
		buf := make([]byte, 4096)
		for {
			n, err := ptmx.Read(buf)
			if err != nil {
				return
			}
			if n > 0 {
				text := toUTF8(buf[:n])
				writeMessage([]byte(text))
			}
		}
	}()

	for {
		_, message, err := conn.ReadMessage()
		if err != nil {
			break
		}
		if _, err := ptmx.Write(message); err != nil {
			break
		}
	}

	cmd.Process.Kill()
	cmd.Wait()
	wg.Wait()
}

// handlePipeMode 使用 pipe 处理终端（Windows）
func (tc *TerminalController) handlePipeMode(conn *websocket.Conn) {
	// 发送 pipe 模式标识
	conn.WriteMessage(websocket.TextMessage, []byte("__PIPE_MODE__"))

	cmd := utils.NewShellCmd()

	if absDir, err := filepath.Abs(constant.ScriptsWorkDir); err == nil {
		cmd.Dir = absDir
	}

	stdin, err := cmd.StdinPipe()
	if err != nil {
		conn.WriteMessage(websocket.TextMessage, []byte("Error: "+err.Error()))
		return
	}

	stdout, err := cmd.StdoutPipe()
	if err != nil {
		conn.WriteMessage(websocket.TextMessage, []byte("Error: "+err.Error()))
		return
	}

	stderr, err := cmd.StderrPipe()
	if err != nil {
		conn.WriteMessage(websocket.TextMessage, []byte("Error: "+err.Error()))
		return
	}

	if err := cmd.Start(); err != nil {
		conn.WriteMessage(websocket.TextMessage, []byte("Error: "+err.Error()))
		return
	}

	var wg sync.WaitGroup
	var connMu sync.Mutex

	writeMessage := func(data []byte) {
		connMu.Lock()
		defer connMu.Unlock()
		conn.WriteMessage(websocket.TextMessage, data)
	}

	readOutput := func(reader io.Reader) {
		defer wg.Done()
		defer func() { recover() }()
		buf := make([]byte, 4096)
		for {
			n, err := reader.Read(buf)
			if err != nil {
				return
			}
			if n > 0 {
				text := toUTF8(buf[:n])
				writeMessage([]byte(text))
			}
		}
	}

	wg.Add(2)
	go readOutput(stdout)
	go readOutput(stderr)

	for {
		_, message, err := conn.ReadMessage()
		if err != nil {
			break
		}
		if _, err := stdin.Write(message); err != nil {
			break
		}
	}

	stdin.Close()
	cmd.Process.Kill()
	cmd.Wait()
	wg.Wait()
}

// ExecuteShellCommand 执行单个命令并返回结果
func (tc *TerminalController) ExecuteShellCommand(c *gin.Context) {
	var req struct {
		Command string `json:"command" binding:"required"`
	}

	if err := c.ShouldBindJSON(&req); err != nil {
		utils.BadRequest(c, err.Error())
		return
	}

	cmd := utils.NewShellCommandCmd(req.Command)
	output, err := cmd.CombinedOutput()

	if err != nil {
		utils.Success(c, gin.H{
			"output": string(output),
			"error":  err.Error(),
		})
		return
	}

	utils.Success(c, gin.H{
		"output": string(output),
	})
}