package handlers

import (
	"crypto/rand"
	"errors"
	"net/http"
	"strconv"
	"time"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"

	"everypublish/server/internal/api/response"
	"everypublish/server/internal/models"
	"everypublish/server/internal/ws"
)

// AgentHandler 设备配对与列表
type AgentHandler struct {
	DB  *gorm.DB
	Hub *ws.Hub
}

const pairAlphabet = "ABCDEFGHJKMNPQRSTUVWXYZ23456789"

var errPairCodeUsed = errors.New("pair code already used")

func randCode(n int) string {
	b := make([]byte, n)
	_, _ = rand.Read(b)
	for i := range b {
		b[i] = pairAlphabet[int(b[i])%len(pairAlphabet)]
	}
	return string(b)
}

// PairCode 生成配对码（5 分钟一次性）
func (h *AgentHandler) PairCode(c *gin.Context) {
	pc := models.PairingCode{
		WorkspaceID: c.GetUint64("wsid"),
		Code:        randCode(6),
		ExpiresAt:   time.Now().Add(5 * time.Minute),
	}
	if err := h.DB.Create(&pc).Error; err != nil {
		response.Fail(c, http.StatusInternalServerError, 5000, "生成配对码失败")
		return
	}
	response.Audit(c, "agent.pair_code", "pairing:"+itoa(pc.ID), gin.H{"code": pc.Code})
	response.OK(c, gin.H{"code": pc.Code, "expiresAt": pc.ExpiresAt})
}

// Pair 设备配对（无鉴权，凭一次性码；注册 Ed25519 公钥）
func (h *AgentHandler) Pair(c *gin.Context) {
	var req struct {
		Code       string `json:"code" binding:"required"`
		DeviceName string `json:"deviceName" binding:"required"`
		OS         string `json:"os"`
		Version    string `json:"version"`
		PublicKey  string `json:"publicKey" binding:"required"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		response.Fail(c, http.StatusBadRequest, 1001, "参数不合法")
		return
	}
	var pc models.PairingCode
	if err := h.DB.Where("code = ? and used = ?", req.Code, false).First(&pc).Error; err != nil {
		response.Fail(c, http.StatusBadRequest, 2006, "配对码无效")
		return
	}
	if time.Now().After(pc.ExpiresAt) {
		response.Fail(c, http.StatusGone, 2006, "配对码已过期")
		return
	}
	device := models.AgentDevice{
		WorkspaceID: pc.WorkspaceID,
		Name:        req.DeviceName,
		OS:          req.OS,
		Version:     req.Version,
		PublicKey:   req.PublicKey,
		Status:      "offline",
		PairedAt:    time.Now(),
	}
	err := h.DB.Transaction(func(tx *gorm.DB) error {
		// 原子占用：仅当仍 unused 且未过期时置 used=true；RowsAffected==1 才视为抢到，
		// 防止并发用同一码配出多台设备。
		res := tx.Model(&models.PairingCode{}).
			Where("id = ? and used = ?", pc.ID, false).
			Update("used", true)
		if res.Error != nil {
			return res.Error
		}
		if res.RowsAffected != 1 {
			return errPairCodeUsed
		}
		if err := tx.Create(&device).Error; err != nil {
			return err
		}
		if err := tx.Model(&models.PairingCode{}).Where("id = ?", pc.ID).
			Update("device_id", device.ID).Error; err != nil {
			return err
		}
		return nil
	})
	if err != nil {
		if err == errPairCodeUsed {
			response.Fail(c, http.StatusBadRequest, 2006, "配对码已被使用")
			return
		}
		response.Fail(c, http.StatusInternalServerError, 5000, "配对失败")
		return
	}
	response.OK(c, gin.H{"deviceId": device.ID, "workspaceId": device.WorkspaceID})
}

// Devices 设备列表（在线状态来自 Hub，此处以 DB 状态兜底）
func (h *AgentHandler) Devices(c *gin.Context) {
	var list []models.AgentDevice
	h.DB.Where("workspace_id = ?", c.GetUint64("wsid")).Order("id desc").Find(&list)
	response.OK(c, gin.H{"list": list})
}

// Revoke 吊销设备并强制断开（owner/admin）
func (h *AgentHandler) Revoke(c *gin.Context) {
	if !isAdminRole(c.GetString("mrole")) {
		response.Fail(c, http.StatusForbidden, 1003, "仅管理员可吊销设备")
		return
	}
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		response.Fail(c, http.StatusBadRequest, 1001, "参数不合法")
		return
	}
	var device models.AgentDevice
	if err = h.DB.Where("id = ? and workspace_id = ?", id, c.GetUint64("wsid")).First(&device).Error; err != nil {
		response.Fail(c, http.StatusNotFound, 1004, "设备不存在")
		return
	}
	if err = h.DB.Model(&device).Updates(map[string]interface{}{"revoked": true, "status": "offline"}).Error; err != nil {
		response.Fail(c, http.StatusInternalServerError, 5000, "吊销失败")
		return
	}
	if h.Hub != nil {
		h.Hub.KickAgent(device.ID)
	}
	response.Audit(c, "agent.revoke", "device:"+itoa(id), nil)
	response.OK(c, nil)
}