// Copyright 2026 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package credstore

import (
	"errors"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"github.com/zalando/go-keyring"
)

// mockStore is a simple mock implementing Store[T] for testing.
type mockStore[T any] struct {
	data map[string]T
	name string
}

func newMockStore[T any](name string) *mockStore[T] {
	return &mockStore[T]{
		data: make(map[string]T),
		name: name,
	}
}

func (m *mockStore[T]) Load(clientID string) (T, error) {
	data, ok := m.data[clientID]
	if !ok {
		var zero T
		return zero, ErrNotFound
	}
	return data, nil
}

func (m *mockStore[T]) Save(clientID string, data T) error {
	m.data[clientID] = data
	return nil
}

func (m *mockStore[T]) Delete(clientID string) error {
	delete(m.data, clientID)
	return nil
}

func (m *mockStore[T]) String() string {
	return m.name
}

// mockProberStore implements both Store[T] and Prober.
type mockProberStore[T any] struct {
	mockStore[T]
	probeResult bool
}

func newMockProberStore[T any](name string, probeResult bool) *mockProberStore[T] {
	return &mockProberStore[T]{
		mockStore:   mockStore[T]{data: make(map[string]T), name: name},
		probeResult: probeResult,
	}
}

func (m *mockProberStore[T]) Probe() bool {
	return m.probeResult
}

func TestSecureStoreUsesKeyringWhenProbeSucceeds(t *testing.T) {
	kr := newMockProberStore[Token]("keyring: test", true)
	file := newMockStore[Token]("file: test")

	store := NewSecureStore[Token](kr, file)

	tok := Token{
		AccessToken: "test-token",
		ClientID:    "test-client",
		ExpiresAt:   time.Now().Add(1 * time.Hour),
	}
	require.NoError(t, store.Save(tok.ClientID, tok))

	// Should be in keyring, not file
	assert.Contains(t, kr.data, "test-client")
	assert.NotContains(t, file.data, "test-client")

	loaded, err := store.Load("test-client")
	require.NoError(t, err)
	assert.Equal(t, "test-token", loaded.AccessToken)
	assert.Equal(t, "keyring: test", store.String())
}

func TestSecureStoreFallsBackToFileWhenProbeFails(t *testing.T) {
	kr := newMockProberStore[Token]("keyring: test", false)
	file := newMockStore[Token]("file: test")

	store := NewSecureStore[Token](kr, file)

	tok := Token{
		AccessToken: "test-token",
		ClientID:    "test-client",
		ExpiresAt:   time.Now().Add(1 * time.Hour),
	}
	require.NoError(t, store.Save(tok.ClientID, tok))

	// Should be in file, not keyring
	assert.Contains(t, file.data, "test-client")
	assert.NotContains(t, kr.data, "test-client")
	assert.Equal(t, "file: test", store.String())
}

func TestSecureStoreFallsBackWhenKrNotProber(t *testing.T) {
	// kr does not implement Prober, should fall back to file
	kr := newMockStore[Token]("keyring: test")
	file := newMockStore[Token]("file: test")

	store := NewSecureStore[Token](kr, file)

	assert.Equal(t, "file: test", store.String())
}

func TestSecureStoreDelete(t *testing.T) {
	kr := newMockProberStore[Token]("keyring: test", true)
	file := newMockStore[Token]("file: test")
	store := NewSecureStore[Token](kr, file)

	tok := Token{
		AccessToken: "test-token",
		ClientID:    "test-client",
	}
	require.NoError(t, store.Save(tok.ClientID, tok))
	require.NoError(t, store.Delete("test-client"))

	_, err := store.Load("test-client")
	assert.ErrorIs(t, err, ErrNotFound)
}

// TestDefaultTokenSecureStoreRoundTrip verifies the happy path: with a working
// keyring, Save writes AES-256-GCM ciphertext (v1: prefix) to filePath+".enc",
// Load returns the identical token, and Delete makes Load return ErrNotFound.
func TestDefaultTokenSecureStoreRoundTrip(t *testing.T) {
	keyring.MockInit() // avoid touching the real OS keyring
	plainPath := filepath.Join(t.TempDir(), "credentials.json")
	store := DefaultTokenSecureStore("test-service", plainPath)

	tok := Token{
		AccessToken:  "secret-access-token",
		RefreshToken: "secret-refresh-token",
		TokenType:    "Bearer",
		ExpiresAt:    time.Now().Add(1 * time.Hour).Truncate(time.Second),
		ClientID:     "test-client",
	}
	require.NoError(t, store.Save(tok.ClientID, tok))

	loaded, err := store.Load("test-client")
	require.NoError(t, err)
	assert.Equal(t, tok.AccessToken, loaded.AccessToken)
	assert.Equal(t, tok.RefreshToken, loaded.RefreshToken)
	assert.Equal(t, tok.TokenType, loaded.TokenType)
	assert.Equal(t, tok.ClientID, loaded.ClientID)
	assert.True(t, tok.ExpiresAt.Equal(loaded.ExpiresAt))

	// The encrypted file must exist and contain only v1:-prefixed ciphertext.
	raw, err := os.ReadFile(plainPath + ".enc")
	require.NoError(t, err)
	assert.Contains(t, string(raw), `"v1:`)
	assert.NotContains(t, string(raw), "secret-access-token")
	assert.NotContains(t, string(raw), "secret-refresh-token")

	// No plaintext fallback file may be created.
	_, err = os.Stat(plainPath)
	assert.ErrorIs(t, err, os.ErrNotExist)

	require.NoError(t, store.Delete("test-client"))
	_, err = store.Load("test-client")
	assert.ErrorIs(t, err, ErrNotFound)
}

// TestDefaultTokenSecureStoreFallbackWithoutKeyring verifies the CI/headless
// path: when the OS keyring is unavailable, the store falls back to the
// plaintext file and Save/Load still succeed.
func TestDefaultTokenSecureStoreFallbackWithoutKeyring(t *testing.T) {
	keyring.MockInitWithError(errors.New("keyring unavailable"))
	t.Cleanup(keyring.MockInit) // restore a working mock for later tests

	plainPath := filepath.Join(t.TempDir(), "credentials.json")
	store := DefaultTokenSecureStore("test-service", plainPath)

	tok := Token{
		AccessToken: "fallback-token",
		ClientID:    "test-client",
	}
	require.NoError(t, store.Save(tok.ClientID, tok))
	assert.Equal(t, "file: "+plainPath, store.String())

	loaded, err := store.Load("test-client")
	require.NoError(t, err)
	assert.Equal(t, "fallback-token", loaded.AccessToken)

	// Plaintext file exists, encrypted file does not.
	raw, err := os.ReadFile(plainPath)
	require.NoError(t, err)
	assert.True(t, strings.Contains(string(raw), "fallback-token"))
	_, err = os.Stat(plainPath + ".enc")
	assert.ErrorIs(t, err, os.ErrNotExist)
}

// Format-stability fixture: a fixed master key and a credentials.json.enc
// file in the "v1:" AES-256-GCM format. They must remain decryptable so
// users do not lose their stored tokens when upgrading tea.
const (
	fixtureMasterKeyB64 = "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8="
	fixtureEncFile      = `{
  "data": {
    "fixture-login": "v1:KallKg6+rJ3Sbxf6Kz1E5yF9bRgqq0Of00ZSctEY2Dem6qpm2wt9RdpCqSMdoX9AQ6/u9ujuC4a0LPb1n3ryXm0EJGrFpXHff0ukpatB1OZhdYlgcbuA8EFpPF/rSgN1hMXOXYQFn64r3iIEaXkgW69s887RNLbaxXALy3o7qvzmEWXuTPtEy3x+J4O6pmbDusvqgVWrOLPT9A1fSJnXWcViUcG13JF0X36NFPc149hsf1S0OUB2Uwn3hVl8jIISaw=="
  }
}`
)

// TestDefaultTokenSecureStoreReadsFixtureData verifies on-disk format
// compatibility: the AES-256-GCM "v1:" ciphertext format (as produced by the
// original SDK implementation) with the master key in the keyring is
// decrypted correctly.
func TestDefaultTokenSecureStoreReadsFixtureData(t *testing.T) {
	keyring.MockInit()
	require.NoError(t, keyring.Set("tea-cli", masterKeyUser, fixtureMasterKeyB64))

	plainPath := filepath.Join(t.TempDir(), "credentials.json")
	require.NoError(t, os.WriteFile(plainPath+".enc", []byte(fixtureEncFile), 0o600))

	store := DefaultTokenSecureStore("tea-cli", plainPath)

	loaded, err := store.Load("fixture-login")
	require.NoError(t, err)
	assert.Equal(t, "fixture-access-token", loaded.AccessToken)
	assert.Equal(t, "fixture-refresh-token", loaded.RefreshToken)
	assert.Equal(t, "Bearer", loaded.TokenType)
	assert.Equal(t, "fixture-login", loaded.ClientID)
	assert.True(t, loaded.ExpiresAt.Equal(time.Date(2027, 1, 2, 3, 4, 5, 0, time.UTC)))
}