package gocmdDaemon

import (
	"encoding/json"
	"fmt"
	"net"
	"os"
	"strings"

	"github.com/google/uuid"
)

type CmdDaemon struct {
	Name       string // app cli command name
	SocketPath string // unix socket path
	cmds       map[string]CmdHandler
}
type CmdRequest struct {
	Id      string `json:"id"`
	Cmd     string `json:"cmd"`
	Args    string `json:"args"`
	IsDebug bool   `json:"debug"`
}
type CmdResponse struct {
	Id       string `json:"id"`
	Data     string `json:"data"`
	Error    string `json:"error"`
	Continue bool   `json:"continue"`
}

type CmdConn struct {
	net.Conn
	Id string
}

func (c *CmdConn) Write(d string) error {
	resp := CmdResponse{
		Id:       c.Id,
		Data:     d,
		Continue: true,
	}
	return Write(c.Conn, resp)
}
func (c *CmdConn) WriteError(err error, isContinue bool) error {
	resp := CmdResponse{
		Id:       c.Id,
		Error:    err.Error(),
		Continue: isContinue,
	}
	return Write(c.Conn, resp)
}
func (c *CmdConn) End(d string) error {
	resp := CmdResponse{
		Id:       c.Id,
		Data:     d,
		Continue: false,
	}
	return Write(c.Conn, resp)
}

type CmdHandler interface {
	Handle(conn *CmdConn, req *CmdRequest) error
	Description() string
	Usage() string
}

// Listen 启动守护进程并监听Unix socket上的连接
// 参数:
//
//	c: CmdDaemon 实例指针
//
// 返回:
//
//	error: 监听过程中发生的错误（如果有）
func (c *CmdDaemon) Listen() error {
	// 删除已存在的 socket 文件（如果存在）
	if err := os.Remove(c.SocketPath); err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("failed to remove existing socket file: %v", err)
	}

	// 监听 unix socket
	listener, err := net.Listen("unix", c.SocketPath)
	if err != nil {
		return fmt.Errorf("failed to listen on socket: %v", err)
	}
	defer listener.Close()

	// 设置 socket 文件权限
	if err := os.Chmod(c.SocketPath, 0777); err != nil {
		return fmt.Errorf("failed to set socket file permissions: %v", err)
	}

	for {
		conn, err := listener.Accept()
		if err != nil {
			return fmt.Errorf("failed to accept connection: %v", err)
		}

		// 处理每个连接
		go func(conn net.Conn) {
			defer conn.Close()

			req, err := Read[CmdRequest](conn)
			if err != nil {
				_ = Write(conn, CmdResponse{
					Error:    "failed to read request: " + err.Error(),
					Continue: false,
				})
				return
			}

			cmdHandler, ok := c.cmds[req.Cmd]
			if !ok {
				_ = Write(conn, CmdResponse{
					Error:    "unknown command: " + req.Cmd + "\n" + c.Usage(),
					Continue: false,
				})
				return
			}

			// 执行命令处理程序
			cmdConn := &CmdConn{Conn: conn, Id: req.Id}
			err = cmdHandler.Handle(cmdConn, req)
			if err != nil {
				_ = cmdConn.End(err.Error() + cmdHandler.Usage())
			}
		}(conn)
	}
}

// Usage 生成命令使用说明
// 参数:
//
//	c: CmdDaemon 实例指针
//
// 返回:
//
//	string: 命令使用说明字符串
func (c *CmdDaemon) Usage() string {
	usage := fmt.Sprintf("Usage: %s [options] <command> [args...]\n\n", c.Name)
	usage += "Options:\n"
	usage += "  -d, --debug  Run command in debug mode\n\n"
	usage += "Commands:\n"
	for cmd, handler := range c.cmds {
		usage += fmt.Sprintf("  %-10s %s\n", cmd, handler.Description())
	}
	return usage
}

func (c *CmdDaemon) RegisterCmd(cmd string, handler CmdHandler) {
	c.cmds[cmd] = handler
}

// isDebug 检查给定的命令是否是调试标志
// 参数:
//
//	c: CmdDaemon 实例指针
//	cmd: 要检查的命令字符串
//
// 返回:
//
//	bool: 如果是调试标志返回true，否则返回false
func (c *CmdDaemon) isDebug(cmd string) bool {

	return cmd == "--debug" || cmd == "-d"
}

// Run 执行客户端命令并通过Unix socket与守护进程通信
// 参数:
//
//	c: CmdDaemon 实例指针
//
// 返回:
//
//	error: 执行过程中发生的错误（如果有）
func (c *CmdDaemon) Run() error {
	// 从命令参数中解析出是否debug 子命令和剩余参数字符串
	args := os.Args[1:]
	isDebug := c.isDebug(args[0])
	var remainingArgs []string
	cmd := ""
	if isDebug {
		if len(args) > 1 {
			cmd = args[1]
			remainingArgs = args[2:]
		} else {
			cmd = "help"
			isDebug = false
			remainingArgs = []string{}
		}
	} else {
		if len(args) > 0 {
			cmd = args[0]
			remainingArgs = args[1:]
		} else {
			cmd = "help"
			isDebug = false
			remainingArgs = []string{}
		}
	}
	cmdReq := CmdRequest{
		Args:    strings.Join(remainingArgs, " "),
		Cmd:     cmd,
		Id:      uuid.New().String(),
		IsDebug: isDebug,
	}
	// dial unix socket
	conn, err := net.Dial("unix", c.SocketPath)
	if err != nil {
		return err
	}
	defer conn.Close()
	// send cmd request
	cmdReqJson, err := json.Marshal(cmdReq)
	if err != nil {
		return err
	}
	_, err = conn.Write(cmdReqJson)
	if err != nil {
		return err
	}

	for {

		resp, err := Read[CmdResponse](conn)
		if err != nil {
			return err
		}
		if resp.Error != "" {
			fmt.Println(resp.Error)
		}
		if !resp.Continue {
			break
		}
	}
	return nil

}