package middleware

import (
	"strings"

	"affiliate_dash/internal/model"
	"affiliate_dash/internal/pkg/jwt"
	"affiliate_dash/internal/pkg/response"
	"affiliate_dash/internal/service"

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

const (
	CtxUserID              = "user_id"
	CtxUsername            = "username"
	CtxRole                = "role"
	CtxMerchantRole        = "merchant_role"
	CtxMerchantPermissions = "merchant_permissions"
)

func Auth(jm *jwt.Manager) gin.HandlerFunc {
	return func(c *gin.Context) {
		auth := c.GetHeader("Authorization")
		if auth == "" {
			response.Unauthorized(c, "未登录")
			c.Abort()
			return
		}
		parts := strings.SplitN(auth, " ", 2)
		if len(parts) != 2 || !strings.EqualFold(parts[0], "Bearer") {
			response.Unauthorized(c, "无效的认证头")
			c.Abort()
			return
		}
		claims, err := jm.Parse(parts[1])
		if err != nil {
			response.Unauthorized(c, "登录已过期，请重新登录")
			c.Abort()
			return
		}
		c.Set(CtxUserID, claims.UserID)
		c.Set(CtxUsername, claims.Username)
		c.Set(CtxRole, claims.Role)
		c.Next()
	}
}

func RequireRole(roles ...string) gin.HandlerFunc {
	set := make(map[string]struct{}, len(roles))
	for _, r := range roles {
		set[r] = struct{}{}
	}
	return func(c *gin.Context) {
		role, _ := c.Get(CtxRole)
		roleStr, _ := role.(string)
		if _, ok := set[roleStr]; !ok {
			response.Forbidden(c, "权限不足")
			c.Abort()
			return
		}
		c.Next()
	}
}

func GetUserID(c *gin.Context) uint {
	v, _ := c.Get(CtxUserID)
	id, _ := v.(uint)
	return id
}

func GetRole(c *gin.Context) string {
	v, _ := c.Get(CtxRole)
	role, _ := v.(string)
	return role
}

// Tenant 根据 X-Merchant-ID（商户 ID 或编码）解析当前后台请求所属商户。
// 未指定时选择该账号的默认商户，确保旧后台继续落到“自营商户”。
func Tenant(tenantSvc *service.TenantService) gin.HandlerFunc {
	return func(c *gin.Context) {
		merchantRef := c.GetHeader("X-Merchant-ID")
		if GetRole(c) == model.RoleAdmin && merchantRef != "" {
			merchant, err := tenantSvc.ResolveMerchantForAdmin(merchantRef)
			if err != nil {
				response.Forbidden(c, err.Error())
				c.Abort()
				return
			}
			c.Set(CtxMerchantID, merchant.ID)
			c.Set(CtxMerchantRole, model.MemberRoleOwner)
			permissions, _ := tenantSvc.MerchantRolePermissions(merchant.ID, model.MemberRoleOwner)
			c.Set(CtxMerchantPermissions, permissions)
			c.Next()
			return
		}
		member, err := tenantSvc.ResolveMember(GetUserID(c), merchantRef)
		if err != nil {
			response.Forbidden(c, err.Error())
			c.Abort()
			return
		}
		c.Set(CtxMerchantID, member.MerchantID)
		c.Set(CtxMerchantRole, member.Role)
		permissions, err := tenantSvc.MerchantRolePermissions(member.MerchantID, member.Role)
		if err != nil {
			response.Forbidden(c, err.Error())
			c.Abort()
			return
		}
		c.Set(CtxMerchantPermissions, permissions)
		c.Next()
	}
}

func RequireMerchantRole(roles ...string) gin.HandlerFunc {
	allowed := make(map[string]struct{}, len(roles))
	for _, role := range roles {
		allowed[role] = struct{}{}
	}
	return func(c *gin.Context) {
		value, _ := c.Get(CtxMerchantRole)
		role, _ := value.(string)
		if _, ok := allowed[role]; !ok {
			response.Forbidden(c, "商户权限不足")
			c.Abort()
			return
		}
		c.Next()
	}
}

// RequireMerchantPermissions 按当前商户的角色权限校验。保留角色通过兼容权限集计算，
// 自定义角色从 merchant_roles 读取，所有列出的权限均需具备。
func RequireMerchantPermissions(tenantSvc *service.TenantService, permissions ...string) gin.HandlerFunc {
	return func(c *gin.Context) {
		granted := GetMerchantPermissions(c)
		for _, permission := range permissions {
			if _, ok := granted[permission]; !ok {
				response.Forbidden(c, "商户权限不足")
				c.Abort()
				return
			}
		}
		c.Next()
	}
}

func GetMerchantPermissions(c *gin.Context) map[string]struct{} {
	value, _ := c.Get(CtxMerchantPermissions)
	permissions, _ := value.(map[string]struct{})
	return permissions
}

func GetMerchantRole(c *gin.Context) string {
	value, _ := c.Get(CtxMerchantRole)
	role, _ := value.(string)
	return role
}