package middleware

import (
	"context"
	"net/http"
	"strings"

	"5803025048/W04/internal/models"
)

type contextKey string

const UserIDKey contextKey = "user_id"

// GetUserID mengambil user id yang disimpan RequireAuth di context request.
func GetUserID(ctx context.Context) string {
	if val, ok := ctx.Value(UserIDKey).(string); ok {
		return val
	}
	return ""
}

// SessionLookup adalah interface kecil yang dibutuhkan middleware:
// mencari session (dan user id-nya) dari sebuah token.
// *store.SessionStore memenuhi interface ini tanpa perubahan.
type SessionLookup interface {
	Get(ctx context.Context, token string) (*models.Session, error)
}

type AuthMiddleware struct {
	sessions SessionLookup
}

func NewAuthMiddleware(sessions SessionLookup) *AuthMiddleware {
	return &AuthMiddleware{sessions: sessions}
}

const bearerPrefix = "Bearer "

// BearerToken mengambil token dari header "Authorization: Bearer <token>".
// Mengembalikan false jika header tidak ada, skema bukan Bearer, atau token kosong.
func BearerToken(r *http.Request) (string, bool) {
	h := r.Header.Get("Authorization")
	if len(h) <= len(bearerPrefix) || !strings.EqualFold(h[:len(bearerPrefix)], bearerPrefix) {
		return "", false
	}
	token := strings.TrimSpace(h[len(bearerPrefix):])
	if token == "" {
		return "", false
	}
	return token, true
}

func unauthorized(w http.ResponseWriter) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusUnauthorized)
	_, _ = w.Write([]byte(`{"error":"Unauthorized"}` + "\n"))
}

func (m *AuthMiddleware) RequireAuth(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		token, ok := BearerToken(r)
		if !ok {
			unauthorized(w)
			return
		}

		session, err := m.sessions.Get(r.Context(), token)
		if err != nil || session == nil {
			unauthorized(w)
			return
		}

		ctx := context.WithValue(r.Context(), UserIDKey, session.UserID)
		next.ServeHTTP(w, r.WithContext(ctx))
	})
}