package middleware

import (
	"net/http"
	"strings"

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

	"git.gobha.me/xcaliber/chat-switchboard/config"
	"git.gobha.me/xcaliber/chat-switchboard/database"
)

// Claims represents the JWT payload.
type Claims struct {
	UserID string `json:"user_id"`
	Email  string `json:"email"`
	jwt.RegisteredClaims
}

// Auth returns a Gin middleware that validates JWT bearer tokens.
// When no database is connected (unmanaged mode), all requests
// are allowed through without authentication.
func Auth(cfg *config.Config) gin.HandlerFunc {
	return func(c *gin.Context) {
		// Skip auth when running without a database (unmanaged mode)
		if !database.IsConnected() {
			c.Next()
			return
		}

		header := c.GetHeader("Authorization")
		if header == "" {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{
				"error": "missing authorization header",
			})
			return
		}

		tokenString := strings.TrimPrefix(header, "Bearer ")
		if tokenString == header {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{
				"error": "invalid authorization format",
			})
			return
		}

		claims := &Claims{}
		token, err := jwt.ParseWithClaims(tokenString, claims, func(t *jwt.Token) (interface{}, error) {
			if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
				return nil, jwt.ErrSignatureInvalid
			}
			return []byte(cfg.JWTSecret), nil
		})

		if err != nil || !token.Valid {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{
				"error": "invalid or expired token",
			})
			return
		}

		// Store claims in context for downstream handlers
		c.Set("user_id", claims.UserID)
		c.Set("email", claims.Email)
		c.Next()
	}
}