package middleware

import (
	"net/http"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v5"
	"gorm.io/gorm"

	"github.com/wangjia/jiu/backend/config"
	"github.com/wangjia/jiu/backend/internal/model"
)

type Claims struct {
	UserID           uint64 `json:"user_id"`
	ShopID           uint64 `json:"shop_id"`
	Role             string `json:"role"`
	SID              string `json:"sid,omitempty"`     // 服务端会话标识（user_sessions.sid）
	LicenseExpiresAt *int64 `json:"lic_exp,omitempty"` // unix seconds; nil = perpetual
	jwt.RegisteredClaims
}

const (
	CtxUserID           = "user_id"
	CtxShopID           = "shop_id"
	CtxRole             = "role"
	CtxSID              = "sid"
	CtxLicenseExpiresAt = "lic_exp"
)

// lastSeenThrottle 控制 last_seen_at 写频率，避免每请求一写。
const lastSeenThrottle = 30 * time.Second

func JWT(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		authHeader := c.GetHeader("Authorization")
		if authHeader == "" || !strings.HasPrefix(authHeader, "Bearer ") {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "missing token"})
			return
		}

		tokenStr := strings.TrimPrefix(authHeader, "Bearer ")
		claims := &Claims{}
		token, err := jwt.ParseWithClaims(tokenStr, claims, func(t *jwt.Token) (interface{}, error) {
			return []byte(config.C.JWT.Secret), nil
		})
		if err != nil || !token.Valid {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "invalid token"})
			return
		}

		// 会话校验：带 sid 的 token 必须对应一条未撤销会话（支持踢人/登出/禁用即时失效）。
		// 存量无 sid 的 token 过渡放行（其 access ≤60min 过期后会换到带 sid 的会话）。
		if claims.SID != "" {
			// 一次查询同时取会话 + 用户启用状态：兜底「直接改库 is_active=0」也能即时下线。
			var row struct {
				model.UserSession
				IsActive  bool
				DeletedAt *time.Time
			}
			err := db.Table("user_sessions AS s").
				Select("s.*, u.is_active AS is_active, u.deleted_at AS deleted_at").
				Joins("LEFT JOIN users u ON u.id = s.user_id").
				Where("s.sid = ?", claims.SID).First(&row).Error
			if err != nil || row.UserSession.RevokedAt != nil {
				c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "session revoked", "code": "SESSION_REVOKED"})
				return
			}
			if !row.IsActive || row.DeletedAt != nil {
				c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "user disabled", "code": "USER_DISABLED"})
				return
			}
			// 节流刷新 last_seen，用于在线状态判定
			if time.Since(row.UserSession.LastSeenAt) > lastSeenThrottle {
				db.Model(&model.UserSession{}).Where("id = ?", row.UserSession.ID).
					Update("last_seen_at", time.Now())
			}
		}

		c.Set(CtxUserID, claims.UserID)
		c.Set(CtxShopID, claims.ShopID)
		c.Set(CtxRole, claims.Role)
		c.Set(CtxSID, claims.SID)
		c.Set(CtxLicenseExpiresAt, claims.LicenseExpiresAt)
		c.Next()
	}
}

// GetSID 从 context 中获取当前会话 sid（可能为空：存量无 sid token）。
func GetSID(c *gin.Context) string {
	v, _ := c.Get(CtxSID)
	s, _ := v.(string)
	return s
}

// GetRole 从 context 中获取当前用户角色。
func GetRole(c *gin.Context) string {
	v, _ := c.Get(CtxRole)
	s, _ := v.(string)
	return s
}

// AdminOnly 仅管理员可访问
func AdminOnly() gin.HandlerFunc {
	return func(c *gin.Context) {
		role, _ := c.Get(CtxRole)
		if role != "admin" && role != "superadmin" {
			c.AbortWithStatusJSON(http.StatusForbidden, gin.H{"error": "admin only"})
			return
		}
		c.Next()
	}
}

// ReadOnly 只读用户禁止写操作
func ReadOnly() gin.HandlerFunc {
	return func(c *gin.Context) {
		role, _ := c.Get(CtxRole)
		if role == "readonly" && c.Request.Method != "GET" {
			// code 供前端区分「角色只读」与「授权过期」(后者由 LicenseGuard 返回 phase)
			c.AbortWithStatusJSON(http.StatusForbidden, gin.H{
				"error": "readonly user",
				"code":  "READONLY_USER",
			})
			return
		}
		c.Next()
	}
}

// GetShopID 从 context 中安全获取 shop_id
func GetShopID(c *gin.Context) uint64 {
	v, _ := c.Get(CtxShopID)
	id, _ := v.(uint64)
	return id
}

// GetUserID 从 context 中安全获取 user_id
func GetUserID(c *gin.Context) uint64 {
	v, _ := c.Get(CtxUserID)
	id, _ := v.(uint64)
	return id
}

// SuperAdminOnly 仅超级管理员可访问
func SuperAdminOnly() gin.HandlerFunc {
	return func(c *gin.Context) {
		role, _ := c.Get(CtxRole)
		if role != "superadmin" {
			c.AbortWithStatusJSON(http.StatusForbidden, gin.H{"error": "superadmin only"})
			return
		}
		c.Next()
	}
}