package handler

import (
	"net/http"
	"time"

	"github.com/freefire/jiang13-bbs/middleware"
	"github.com/freefire/jiang13-bbs/model"
	"github.com/freefire/jiang13-bbs/service"
	"github.com/gin-gonic/gin"
)

var (
	accessCookieMaxAge  = int(service.AccessTokenTTL.Seconds())  // 15 分钟
	refreshCookieMaxAge = int(service.RefreshTokenTTL.Seconds()) // 7 天
)

// setAuthCookies 设置认证 cookie：
// - access token（HttpOnly，15min）
// - refresh token（HttpOnly，7天，Path=/，供 Next middleware 在页面/RSC
//   请求中读取并静默轮转；仅 /api/auth/refresh 端点消费）
// - CSRF token（JS 可读，7天，双提交校验）
// SameSite=Lax：允许外站顶级链接进入时保留登录态（Strict 会导致从外站
// 跳转进来的第一次请求丢 cookie，把已登录用户误判为游客）；状态变更请求
// 另有 CSRF 双提交 token 兜底。生产 HTTPS 下 cookie 名带 __Host- 前缀。
func setAuthCookies(c *gin.Context, accessToken, refreshToken string, secure bool) {
	csrfToken := service.GenerateCSRFToken()

	http.SetCookie(c.Writer, &http.Cookie{
		Name:     service.CookieName,
		Value:    accessToken,
		Path:     "/",
		MaxAge:   accessCookieMaxAge,
		HttpOnly: true,
		Secure:   secure,
		SameSite: http.SameSiteLaxMode,
	})
	http.SetCookie(c.Writer, &http.Cookie{
		Name:     service.RefreshCookieName,
		Value:    refreshToken,
		Path:     "/",
		MaxAge:   refreshCookieMaxAge,
		HttpOnly: true,
		Secure:   secure,
		SameSite: http.SameSiteLaxMode,
	})
	http.SetCookie(c.Writer, &http.Cookie{
		Name:     service.CSRFCookieName,
		Value:    csrfToken,
		Path:     "/",
		MaxAge:   refreshCookieMaxAge,
		HttpOnly: false,
		Secure:   secure,
		SameSite: http.SameSiteLaxMode,
	})
}

// clearAuthCookies 清除所有认证 cookie。
// 除当前名称外，还需兼容清除：
//   - 启用 __Host- 前缀之前的旧无前缀名称（Path=/）
//   - 更早期 Path=/api/auth 的旧 refresh cookie
func clearAuthCookies(c *gin.Context, secure bool) {
	cookies := []struct{ name, path string }{
		{service.CookieName, "/"},
		{service.RefreshCookieName, "/"},
		{service.CSRFCookieName, "/"},
	}
	// 当前生产名称带 __Host- 前缀时，旧无前缀 cookie 仍残留在浏览器中
	if service.CookieName != "j13_token" {
		cookies = append(cookies,
			struct{ name, path string }{"j13_token", "/"},
			struct{ name, path string }{"j13_refresh", "/"},
			struct{ name, path string }{"j13_csrf", "/"},
		)
	}
	// 更早期的 refresh cookie 只挂在 /api/auth 下
	cookies = append(cookies, struct{ name, path string }{"j13_refresh", "/api/auth"})

	for _, ck := range cookies {
		http.SetCookie(c.Writer, &http.Cookie{
			Name:     ck.name,
			Value:    "",
			Path:     ck.path,
			MaxAge:   -1,
			HttpOnly: true,
			Secure:   secure,
			SameSite: http.SameSiteLaxMode,
			Expires:  time.Unix(0, 0),
		})
	}
}

// RegisterRequest 注册请求
type RegisterRequest struct {
	Username string `json:"username" binding:"required,min=3,max=32"`
	Email    string `json:"email" binding:"omitempty,email"`
	Password string `json:"password" binding:"required,min=6,max=64"`
}

// LoginRequest 登录请求
type LoginRequest struct {
	Username string `json:"username" binding:"required"`
	Password string `json:"password" binding:"required"`
}

// Register 用户注册：成功后直接签发登录态（注册即登录，免去手动再登一次）
func (h *Handlers) Register(c *gin.Context) {
	var req RegisterRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	user, err := h.Auth.Register(req.Username, req.Email, req.Password)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	// 自动登录：走与 Login 相同的 token 签发链路
	accessToken, refreshToken, loginUser, err := h.Auth.Login(req.Username, req.Password)
	if err != nil {
		// 签发失败不应让注册白做：仍返回成功，让前端引导去登录页
		c.JSON(http.StatusOK, gin.H{
			"id":       user.ID,
			"username": user.Username,
		})
		return
	}
	setAuthCookies(c, accessToken, refreshToken, !h.Cfg.DevMode)
	c.JSON(http.StatusOK, gin.H{
		"user": gin.H{
			"id":       loginUser.ID,
			"username": loginUser.Username,
			"nickname": loginUser.Nickname,
			"avatar":   loginUser.Avatar,
			"role":     loginUser.Role,
		},
	})
}

// Login 用户登录：access + refresh token 写入 HttpOnly cookie，CSRF 写入可读 cookie
func (h *Handlers) Login(c *gin.Context) {
	var req LoginRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	accessToken, refreshToken, user, err := h.Auth.Login(req.Username, req.Password)
	if err != nil {
		c.JSON(http.StatusUnauthorized, gin.H{"error": err.Error()})
		return
	}
	// dev 模式不设 Secure，生产环境需 HTTPS
	setAuthCookies(c, accessToken, refreshToken, !h.Cfg.DevMode)
	c.JSON(http.StatusOK, gin.H{
		"user": gin.H{
			"id":       user.ID,
			"username": user.Username,
			"nickname": user.Nickname,
			"avatar":   user.Avatar,
			"role":     user.Role,
		},
	})
}

// Refresh 刷新 access token：验证 refresh token，轮转后签发新 access + refresh
func (h *Handlers) Refresh(c *gin.Context) {
	refreshToken, err := c.Cookie(service.RefreshCookieName)
	if err != nil || refreshToken == "" {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "未登录"})
		return
	}
	accessToken, newRefresh, user, err := h.Auth.RotateRefreshToken(refreshToken)
	if err != nil {
		clearAuthCookies(c, !h.Cfg.DevMode)
		c.JSON(http.StatusUnauthorized, gin.H{"error": "登录已过期，请重新登录"})
		return
	}
	setAuthCookies(c, accessToken, newRefresh, !h.Cfg.DevMode)
	c.JSON(http.StatusOK, gin.H{
		"user": gin.H{
			"id":       user.ID,
			"username": user.Username,
			"nickname": user.Nickname,
			"avatar":   user.Avatar,
			"role":     user.Role,
		},
	})
}

// Logout 登出：仅撤销本次请求携带的那枚 refresh token（单设备登出语义，
// 不影响该用户其他设备的登录态），并清除所有认证 cookie。
// access JWT 无状态、15 分钟自然过期；登出后 tv 不递增，属可接受的短窗口。
func (h *Handlers) Logout(c *gin.Context) {
	if refreshToken, err := c.Cookie(service.RefreshCookieName); err == nil && refreshToken != "" {
		h.Auth.RevokeRefreshToken(refreshToken)
	}
	clearAuthCookies(c, !h.Cfg.DevMode)
	c.JSON(http.StatusOK, gin.H{"message": "已登出"})
}

// ChangePasswordRequest 修改密码请求
type ChangePasswordRequest struct {
	OldPassword string `json:"old_password" binding:"required"`
	NewPassword string `json:"new_password" binding:"required,min=6,max=64"`
}

// ChangePassword 修改密码：校验旧密码，更新新密码，清除所有登录态
func (h *Handlers) ChangePassword(c *gin.Context) {
	claims := middleware.CurrentUser(c)
	var req ChangePasswordRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	if err := h.Auth.ChangePassword(claims.ID, req.OldPassword, req.NewPassword); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	// 密码已改，token_version 已递增，旧 token 全部失效，清除 cookie 要求重新登录
	clearAuthCookies(c, !h.Cfg.DevMode)
	c.JSON(http.StatusOK, gin.H{"message": "密码修改成功，请重新登录"})
}

// meUserBody 统一的用户信息响应体（Me/Login/Refresh 共用形状）
func meUserBody(user *model.User) gin.H {
	return gin.H{
		"id":        user.ID,
		"username":  user.Username,
		"nickname":  user.Nickname,
		"avatar":    user.Avatar,
		"signature": user.Signature,
		"email":     user.Email,
		"role":      user.Role,
	}
}

// Me 获取当前用户信息 + 未读通知数（合并为一次请求，供 SSR layout 直出）
func (h *Handlers) Me(c *gin.Context) {
	claims := middleware.CurrentUser(c)
	if claims == nil {
		c.JSON(http.StatusOK, gin.H{"user": nil, "unread_count": 0})
		return
	}
	user, err := h.Auth.GetUserByID(claims.ID)
	if err != nil {
		c.JSON(http.StatusOK, gin.H{"user": nil, "unread_count": 0})
		return
	}
	var unread int64
	if n, err := h.Notification.UnreadCount(claims.ID); err == nil {
		unread = n
	}
	c.JSON(http.StatusOK, gin.H{"user": meUserBody(user), "unread_count": unread})
}