package middleware

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"net/http"
	"strconv"
	"strings"

	"github.com/gin-gonic/gin"
	"github.com/gochat/gochat/internal/auth"
	"github.com/gochat/gochat/internal/model"
	"github.com/google/uuid"
	"gorm.io/gorm"
)

const ConnectorPlatformAppIDKey = "connector_platform_app_id"

func ConnectorServiceAuth(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		setConnectorRequestID(c)
		app, accessToken, ok := authenticateShangwutongConnector(c, db)
		if !ok {
			connectorAuthError(c)
			return
		}
		setConnectorPrincipal(c, db, app, accessToken)
		c.Next()
	}
}

func AuthMiddlewareWithConnectorAllowlist(jwtService *auth.JWTService, db *gorm.DB) gin.HandlerFunc {
	userAuth := AuthMiddlewareWithServiceAndDB(jwtService, db)
	return func(c *gin.Context) {
		if connectorApplicationRoute(c) {
			setConnectorRequestID(c)
			if app, accessToken, ok := authenticateShangwutongConnector(c, db); ok {
				accountID, err := strconv.ParseUint(c.Param("account_id"), 10, 64)
				if err != nil || accountID == 0 {
					connectorPermissionError(c)
					return
				}
				var count int64
				if err := db.WithContext(c.Request.Context()).Model(&model.Permissible{}).Where(
					"platform_app_id = ? AND permissible_type = ? AND permissible_id = ?", app.ID, model.PermissibleTypeAccount, uint(accountID),
				).Count(&count).Error; err != nil || count == 0 {
					connectorPermissionError(c)
					return
				}
				setConnectorPrincipal(c, db, app, accessToken)
				c.Set("connector_account_authorized", true)
				c.Set("account_id", uint(accountID))
				c.Next()
				return
			}
		}
		userAuth(c)
	}
}

func connectorApplicationRoute(c *gin.Context) bool {
	switch c.FullPath() {
	case "/api/v1/accounts/:account_id/conversations/:conversation_id/messages":
		return c.Request.Method == http.MethodPost
	case "/api/v1/accounts/:account_id/conversations/:conversation_id/custom_attributes",
		"/api/v1/accounts/:account_id/conversations/:conversation_id/toggle_status":
		return c.Request.Method == http.MethodPost
	case "/api/v1/accounts/:account_id/conversations/:conversation_id/messages/:message_id":
		return c.Request.Method == http.MethodDelete
	default:
		return false
	}
}

func authenticateShangwutongConnector(c *gin.Context, db *gorm.DB) (*model.PlatformApp, *model.AccessToken, bool) {
	parts := strings.Fields(c.GetHeader("Authorization"))
	if len(parts) != 2 || !strings.EqualFold(parts[0], "Bearer") || strings.TrimSpace(parts[1]) == "" {
		return nil, nil, false
	}
	hash := sha256.Sum256([]byte(parts[1]))
	var accessToken model.AccessToken
	if err := db.WithContext(c.Request.Context()).Where(
		"token = ? AND owner_type = ?", hex.EncodeToString(hash[:]), model.AccessTokenOwnerTypePlatformApp,
	).First(&accessToken).Error; err != nil {
		return nil, nil, false
	}
	var app model.PlatformApp
	if err := db.WithContext(c.Request.Context()).First(&app, accessToken.OwnerID).Error; err != nil || !app.IsActive() || !isShangwutongConnectorApp(&app) {
		return nil, nil, false
	}
	return &app, &accessToken, true
}

func setConnectorPrincipal(c *gin.Context, db *gorm.DB, app *model.PlatformApp, accessToken *model.AccessToken) {
	c.Set(ConnectorPlatformAppIDKey, app.ID)
	c.Set("connector_service_principal", *app)
	_ = db.WithContext(c.Request.Context()).Model(&model.AccessToken{}).Where("id = ?", accessToken.ID).Update("last_used_at", gorm.Expr("CURRENT_TIMESTAMP")).Error
}

func setConnectorRequestID(c *gin.Context) {
	requestID := strings.TrimSpace(c.GetHeader("X-Request-ID"))
	if requestID == "" {
		requestID = uuid.NewString()
	}
	c.Set("request_id", requestID)
	c.Header("X-Request-ID", requestID)
}

func ConnectorPlatformAppID(c *gin.Context) uint {
	value, _ := c.Get(ConnectorPlatformAppIDKey)
	id, _ := value.(uint)
	return id
}

func IsConnectorService(c *gin.Context) bool {
	return ConnectorPlatformAppID(c) != 0
}

func isShangwutongConnectorApp(app *model.PlatformApp) bool {
	if app == nil || app.Type != "integration" {
		return false
	}
	config := map[string]any{}
	if len(app.Config) == 0 || json.Unmarshal(app.Config, &config) != nil {
		return false
	}
	connector, _ := config["connector"].(string)
	return connector == "shangwutong"
}

func connectorAuthError(c *gin.Context) {
	c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": gin.H{
		"code": "unauthorized", "message": "connector authentication failed", "retryable": false,
		"request_id": c.GetString("request_id"),
	}})
}

func connectorPermissionError(c *gin.Context) {
	c.AbortWithStatusJSON(http.StatusForbidden, gin.H{"error": gin.H{
		"code": "forbidden", "message": "connector account access denied", "retryable": false,
		"request_id": c.GetString("request_id"),
	}})
}