package authser

import (
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"net/url"
	"strconv"
	"strings"
	"time"
	"videoweb/pub/common/log"
	"videoweb/pub/common/useragent"

	"github.com/gin-gonic/gin"
)

const guestDevIDCookie = "guest_dev_id"

// EnsureGuestOnEnter 页面进入时：无 token 则走游客登录并写 cookie。
// 对应上游 POST /api/app/auth/guest。成功后会把会话补进当前 Request，便于同一次 SSR 直接使用。
func EnsureGuestOnEnter(c *gin.Context) *LoginResp {
	if c == nil || c.Request == nil {
		return nil
	}
	// 已有会话则跳过
	if useragent.TokenFromRequest(c.Request) != "" {
		return nil
	}

	devID := ensureGuestDevID(c)
	env, user, err := GuestLogin(c, GuestLoginReq{
		DevID:    devID,
		DeviceID: devID,
		Channel:  guestChannel(c),
	})
	if err != nil {
		log.Error("ensure guest on enter failed", log.E(err))
		return nil
	}
	if env == nil || env.Code != 200 || user == nil || strings.TrimSpace(user.Token) == "" {
		tip := ""
		if env != nil {
			tip = firstNonEmptyTip(env.Tip, env.Msg)
		}
		log.Error("ensure guest on enter rejected", log.E(fmt.Errorf("code=%v tip=%s", envCode(env), tip)))
		return nil
	}

	SetAuthCookies(c, user)
	patchRequestCookie(c, "token", user.Token)
	return user
}

func dropRequestCookie(c *gin.Context, name string) {
	if c == nil || c.Request == nil || name == "" {
		return
	}
	var parts []string
	for _, ck := range c.Request.Cookies() {
		if ck == nil || ck.Name == name {
			continue
		}
		parts = append(parts, ck.Name+"="+ck.Value)
	}
	c.Request.Header.Set("Cookie", strings.Join(parts, "; "))
}

func ensureGuestDevID(c *gin.Context) string {
	if id := cookieValue(c, guestDevIDCookie); id != "" {
		return id
	}
	id := newGuestDevID()
	secure := c.Request != nil && c.Request.TLS != nil
	setCookie(c, guestDevIDCookie, id, secure)
	patchRequestCookie(c, guestDevIDCookie, id)
	return id
}

func newGuestDevID() string {
	b := make([]byte, 8)
	if _, err := rand.Read(b); err != nil {
		now := time.Now()
		return fmt.Sprintf("%016X%d", uint64(now.UnixNano()), now.UnixMilli())
	}
	return strings.ToUpper(hex.EncodeToString(b)) + strconv.FormatInt(time.Now().UnixMilli(), 10)
}

// guestChannel 为首屏服务端自动游客登录补渠道；cookie 用于复用前端首次归因结果。
func guestChannel(c *gin.Context) string {
	if c == nil || c.Request == nil {
		return ""
	}
	if channel := cookieValue(c, "channel"); channel != "" {
		return channel
	}
	for _, key := range []string{"dc", "ch", "pc"} {
		if channel := strings.TrimSpace(c.Query(key)); channel != "" {
			secure := c.Request.TLS != nil
			setCookie(c, "channel", channel, secure)
			patchRequestCookie(c, "channel", channel)
			return channel
		}
	}
	return ""
}

func patchRequestCookie(c *gin.Context, name, value string) {
	if c == nil || c.Request == nil || name == "" {
		return
	}
	escaped := url.PathEscape(value)
	var parts []string
	for _, ck := range c.Request.Cookies() {
		if ck == nil || ck.Name == name {
			continue
		}
		parts = append(parts, ck.Name+"="+ck.Value)
	}
	parts = append(parts, name+"="+escaped)
	c.Request.Header.Set("Cookie", strings.Join(parts, "; "))
}

func envCode(env *APIEnvelope) int {
	if env == nil {
		return 0
	}
	return env.Code
}

func firstNonEmptyTip(values ...string) string {
	for _, v := range values {
		if strings.TrimSpace(v) != "" {
			return v
		}
	}
	return ""
}