package handler

import (
	"crypto/subtle"
	"encoding/json"
	"io"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"github.com/gin-gonic/gin"

	"laic-backend/common"
	"laic-backend/service"
	"laic-backend/vo"
)

// GetLivePage 直播会话分页列表
func GetLivePage(c *gin.Context) {
	var req vo.LivePageReq
	_ = c.ShouldBindQuery(&req)
	if req.PageNum <= 0 {
		req.PageNum = 1
	}
	if req.PageSize <= 0 {
		req.PageSize = 10
	}
	page, busiErr := service.DefaultLiveService.GetPage(common.GetUserId(c), common.IsAdmin(c), &req)
	if busiErr != nil {
		common.FailWithBusiError(c, busiErr)
		return
	}
	common.OKWithData(c, page)
}

// CreateLiveSession 创建或加入机巢的唯一活动直播会话，并创建观看租约。
func CreateLiveSession(c *gin.Context) {
	dockID := c.Param("dockId")
	if dockID == "" {
		common.FailWithBusiError(c, common.ErrParam)
		return
	}
	var req vo.LiveSessionCreateReq
	_ = c.ShouldBindJSON(&req)
	result, busiErr := service.DefaultLiveService.Join(common.GetUserId(c), common.IsAdmin(c), dockID, &req)
	if busiErr != nil {
		common.FailWithBusiError(c, busiErr)
		return
	}
	common.OKWithData(c, result)
}

// GetLiveSession 获取指定直播会话。
func GetLiveSession(c *gin.Context) {
	dockID, sessionID := c.Param("dockId"), c.Param("streamSessionId")
	if dockID == "" || sessionID == "" {
		common.FailWithBusiError(c, common.ErrParam)
		return
	}
	session, busiErr := service.DefaultLiveService.GetSession(common.GetUserId(c), common.IsAdmin(c), dockID, sessionID)
	if busiErr != nil {
		common.FailWithBusiError(c, busiErr)
		return
	}
	common.OKWithData(c, session)
}

// HeartbeatLiveSession 续期当前用户的观看租约。
func HeartbeatLiveSession(c *gin.Context) {
	dockID, sessionID := c.Param("dockId"), c.Param("streamSessionId")
	if dockID == "" || sessionID == "" {
		common.FailWithBusiError(c, common.ErrParam)
		return
	}
	result, busiErr := service.DefaultLiveService.Heartbeat(common.GetUserId(c), common.IsAdmin(c), dockID, sessionID)
	if busiErr != nil {
		common.FailWithBusiError(c, busiErr)
		return
	}
	common.OKWithData(c, result)
}

// LeaveLiveSession 释放当前用户的观看租约。
func LeaveLiveSession(c *gin.Context) {
	dockID, sessionID := c.Param("dockId"), c.Param("streamSessionId")
	if dockID == "" || sessionID == "" {
		common.FailWithBusiError(c, common.ErrParam)
		return
	}
	if busiErr := service.DefaultLiveService.Leave(common.GetUserId(c), common.IsAdmin(c), dockID, sessionID); busiErr != nil {
		common.FailWithBusiError(c, busiErr)
		return
	}
	common.OK(c)
}

// StartLive 启动直播推流
func StartLive(c *gin.Context) {
	dockID := c.Param("dockId")
	if dockID == "" {
		common.FailWithBusiError(c, common.ErrParam)
		return
	}
	var req vo.LiveStartReq
	_ = c.ShouldBindJSON(&req)
	session, busiErr := service.DefaultLiveService.Start(common.GetUserId(c), common.IsAdmin(c), dockID, &req)
	if busiErr != nil {
		common.FailWithBusiError(c, busiErr)
		return
	}
	common.OKWithData(c, session)
}

func StopLive(c *gin.Context) {
	dockID := c.Param("dockId")
	if dockID == "" {
		common.FailWithBusiError(c, common.ErrParam)
		return
	}
	if busiErr := service.DefaultLiveService.Stop(common.GetUserId(c), common.IsAdmin(c), dockID); busiErr != nil {
		common.FailWithBusiError(c, busiErr)
		return
	}
	common.OK(c)
}

// GetLivePlayURL 获取直播播放地址
func GetLivePlayURL(c *gin.Context) {
	dockID, sessionID := c.Param("dockId"), c.Query("streamSessionId")
	// streamSessionId is optional for compatibility with older web clients. The
	// service resolves it from the caller's active viewer lease when omitted.
	if dockID == "" {
		common.FailWithBusiError(c, common.ErrParam)
		return
	}
	play, busiErr := service.DefaultLiveService.GetPlayURL(common.GetUserId(c), common.IsAdmin(c), dockID, sessionID)
	if busiErr != nil {
		common.FailWithBusiError(c, busiErr)
		return
	}
	common.OKWithData(c, play)
}

const maxAliyunCallbackBodyBytes = 64 * 1024

type aliyunLiveCallback struct {
	EventType  string `json:"eventType"`
	AppName    string `json:"appName"`
	StreamName string `json:"streamName"`
	EventTime  int64  `json:"eventTime"`
}

func HandleAliyunLiveCallback(c *gin.Context) {
	token := common.AppConf.Live.CallbackAuthToken
	provided := strings.TrimPrefix(c.GetHeader("Authorization"), "Bearer ")
	if token == "" || subtle.ConstantTimeCompare([]byte(provided), []byte(token)) != 1 {
		c.Status(http.StatusUnauthorized)
		return
	}

	body, err := io.ReadAll(http.MaxBytesReader(c.Writer, c.Request.Body, maxAliyunCallbackBodyBytes))
	if err != nil {
		c.Status(http.StatusRequestEntityTooLarge)
		return
	}
	callback, err := parseAliyunLiveCallback(c.GetHeader("Content-Type"), body)
	if err != nil || callback.EventType == "" || callback.AppName == "" || callback.StreamName == "" {
		c.Status(http.StatusBadRequest)
		return
	}
	if callback.EventTime > 0 && abs(time.Now().Unix()-normalizeAliyunCallbackTime(callback.EventTime)) > 300 {
		c.Status(http.StatusUnauthorized)
		return
	}
	if err := service.DefaultLiveService.HandleAliyunCallback(callback.EventType, callback.AppName, callback.StreamName, body); err != nil {
		c.Status(http.StatusInternalServerError)
		return
	}
	c.Status(http.StatusNoContent)
}

func parseAliyunLiveCallback(contentType string, body []byte) (aliyunLiveCallback, error) {
	var callback aliyunLiveCallback
	if strings.HasPrefix(contentType, "application/json") {
		err := json.Unmarshal(body, &callback)
		return callback, err
	}
	values, err := url.ParseQuery(string(body))
	if err != nil {
		return callback, err
	}
	callback.EventType = values.Get("eventType")
	callback.AppName = values.Get("appName")
	callback.StreamName = values.Get("streamName")
	if value := values.Get("eventTime"); value != "" {
		callback.EventTime, err = strconv.ParseInt(value, 10, 64)
	}
	return callback, err
}

func normalizeAliyunCallbackTime(value int64) int64 {
	if value > 1_000_000_000_000 {
		return value / 1000
	}
	return value
}

func abs(value int64) int64 {
	if value < 0 {
		return -value
	}
	return value
}