package middleware

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"5803025020/w04/internal/models"
)

// fakeSessionLookup is a hand-written in-memory fake satisfying SessionLookup.
type fakeSessionLookup struct {
	sessions map[string]*models.Session
}

func newFakeSessionLookup() *fakeSessionLookup {
	return &fakeSessionLookup{sessions: make(map[string]*models.Session)}
}

func (f *fakeSessionLookup) add(token, userID string) {
	f.sessions[token] = &models.Session{Token: token, UserID: userID, CreatedAt: time.Now()}
}

var errFakeSessionNotFound = errors.New("fake: session not found")

func (f *fakeSessionLookup) Get(ctx context.Context, token string) (*models.Session, error) {
	sess, ok := f.sessions[token]
	if !ok {
		return nil, errFakeSessionNotFound
	}
	return sess, nil
}

// newRecordingNext returns a next handler that records whether it was called
// and what user id was readable from the request context inside it.
func newRecordingNext(called *bool, gotUserID *string) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		*called = true
		*gotUserID = GetUserID(r.Context())
		w.WriteHeader(http.StatusOK)
	})
}

func assertJSONErrorResponse(t *testing.T, rec *httptest.ResponseRecorder) {
	t.Helper()
	ct := rec.Header().Get("Content-Type")
	if !strings.HasPrefix(ct, "application/json") {
		t.Fatalf("expected Content-Type application/json, got %q", ct)
	}
	var body map[string]any
	if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
		t.Fatalf("expected response body to parse as JSON: %v (body=%s)", err, rec.Body.String())
	}
}

func TestRequireAuth(t *testing.T) {
	fake := newFakeSessionLookup()
	fake.add("validtoken1234567890123456789012", "user-123")
	mw := NewAuthMiddleware(fake)

	t.Run("no Authorization header returns 401 and next is not called", func(t *testing.T) {
		called := false
		var gotUserID string
		rec := httptest.NewRecorder()
		req := httptest.NewRequest(http.MethodGet, "/protected", nil)
		mw.RequireAuth(newRecordingNext(&called, &gotUserID)).ServeHTTP(rec, req)

		if called {
			t.Fatal("expected next handler NOT to be called")
		}
		if rec.Code != http.StatusUnauthorized {
			t.Fatalf("expected 401, got %d", rec.Code)
		}
		assertJSONErrorResponse(t, rec)
	})

	t.Run("Basic scheme returns 401", func(t *testing.T) {
		called := false
		var gotUserID string
		rec := httptest.NewRecorder()
		req := httptest.NewRequest(http.MethodGet, "/protected", nil)
		req.Header.Set("Authorization", "Basic abc")
		mw.RequireAuth(newRecordingNext(&called, &gotUserID)).ServeHTTP(rec, req)

		if called {
			t.Fatal("expected next handler NOT to be called")
		}
		if rec.Code != http.StatusUnauthorized {
			t.Fatalf("expected 401, got %d", rec.Code)
		}
	})

	t.Run("Bearer with empty token returns 401", func(t *testing.T) {
		called := false
		var gotUserID string
		rec := httptest.NewRecorder()
		req := httptest.NewRequest(http.MethodGet, "/protected", nil)
		req.Header.Set("Authorization", "Bearer ")
		mw.RequireAuth(newRecordingNext(&called, &gotUserID)).ServeHTTP(rec, req)

		if called {
			t.Fatal("expected next handler NOT to be called")
		}
		if rec.Code != http.StatusUnauthorized {
			t.Fatalf("expected 401, got %d", rec.Code)
		}
	})

	t.Run("unknown token returns 401", func(t *testing.T) {
		called := false
		var gotUserID string
		rec := httptest.NewRecorder()
		req := httptest.NewRequest(http.MethodGet, "/protected", nil)
		req.Header.Set("Authorization", "Bearer not-a-real-token-000000000000")
		mw.RequireAuth(newRecordingNext(&called, &gotUserID)).ServeHTTP(rec, req)

		if called {
			t.Fatal("expected next handler NOT to be called")
		}
		if rec.Code != http.StatusUnauthorized {
			t.Fatalf("expected 401, got %d", rec.Code)
		}
	})

	t.Run("valid token calls next handler with the authenticated user id in context", func(t *testing.T) {
		called := false
		var gotUserID string
		rec := httptest.NewRecorder()
		req := httptest.NewRequest(http.MethodGet, "/protected", nil)
		req.Header.Set("Authorization", "Bearer validtoken1234567890123456789012")
		mw.RequireAuth(newRecordingNext(&called, &gotUserID)).ServeHTTP(rec, req)

		if !called {
			t.Fatal("expected next handler to be called")
		}
		if gotUserID != "user-123" {
			t.Fatalf("expected user id %q inside next handler, got %q", "user-123", gotUserID)
		}
		if rec.Code != http.StatusOK {
			t.Fatalf("expected 200 from next handler, got %d", rec.Code)
		}
	})

	t.Run("401 responses carry Content-Type application/json and a body that parses as JSON", func(t *testing.T) {
		called := false
		var gotUserID string
		rec := httptest.NewRecorder()
		req := httptest.NewRequest(http.MethodGet, "/protected", nil)
		req.Header.Set("Authorization", "Bearer not-a-real-token-000000000000")
		mw.RequireAuth(newRecordingNext(&called, &gotUserID)).ServeHTTP(rec, req)

		if rec.Code != http.StatusUnauthorized {
			t.Fatalf("expected 401, got %d", rec.Code)
		}
		assertJSONErrorResponse(t, rec)
	})
}