package syncer

import (
	"context"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"testing"
	"time"
)

// fakeBucket 是一个内存版 HF Bucket：只实现同步用到的两个只读端点。
type fakeBucket struct {
	mu    sync.Mutex
	files map[string][]byte
	mtime map[string]time.Time
}

func newFakeBucket() *fakeBucket {
	return &fakeBucket{files: map[string][]byte{}, mtime: map[string]time.Time{}}
}

func (f *fakeBucket) put(path string, content []byte, mtime time.Time) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.files[path] = content
	f.mtime[path] = mtime
}

func (f *fakeBucket) get(path string) ([]byte, bool) {
	f.mu.Lock()
	defer f.mu.Unlock()
	b, ok := f.files[path]
	return b, ok
}

func (f *fakeBucket) handler(bucket string) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		switch {
		case strings.HasPrefix(r.URL.Path, "/api/buckets/"):
			f.mu.Lock()
			type entry struct {
				Type    string `json:"type"`
				Path    string `json:"path"`
				Size    int64  `json:"size"`
				Mtime   string `json:"mtime"`
				XetHash string `json:"xetHash"`
			}
			out := []entry{}
			for p, b := range f.files {
				out = append(out, entry{
					Type: "file", Path: p, Size: int64(len(b)),
					Mtime: f.mtime[p].UTC().Format(time.RFC3339Nano), XetHash: "xet-" + p,
				})
			}
			f.mu.Unlock()
			_ = json.NewEncoder(w).Encode(out)

		case strings.HasPrefix(r.URL.Path, "/buckets/"+bucket+"/resolve/"):
			// Go 已把 %2F 解码回 '/'，直接剥前缀取路径。
			p := strings.TrimPrefix(r.URL.Path, "/buckets/"+bucket+"/resolve/")
			b, ok := f.get(p)
			if !ok {
				http.Error(w, "not found", http.StatusNotFound)
				return
			}
			_, _ = w.Write(b)

		default:
			http.NotFound(w, r)
		}
	})
}

// fakeWriter 记录写入，避免测试真的碰网络/子进程。
type fakeWriter struct {
	mu      sync.Mutex
	put     map[string][]byte
	batches int
	failOn  string
}

func (f *fakeWriter) Name() string { return "fake" }

func (f *fakeWriter) Put(_ context.Context, path string, content []byte) error {
	f.mu.Lock()
	defer f.mu.Unlock()
	if f.failOn == path {
		return fmt.Errorf("boom")
	}
	if f.put == nil {
		f.put = map[string][]byte{}
	}
	f.put[path] = content
	return nil
}

func (f *fakeWriter) PutBatch(_ context.Context, files []PushFile, _ bool) error {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.batches++
	if f.put == nil {
		f.put = map[string][]byte{}
	}
	for _, fl := range files {
		f.put[fl.Path] = fl.Content
	}
	return nil
}

func (f *fakeWriter) Delete(context.Context, string) error { return nil }

func (f *fakeWriter) written(path string) ([]byte, bool) {
	f.mu.Lock()
	defer f.mu.Unlock()
	b, ok := f.put[path]
	return b, ok
}

// authDoc 造一个嵌套形态的凭证文件（网关 auth.Parse 认的形态）。
func authDoc(uid, nick, at, rt string, exp int64) []byte {
	return []byte(fmt.Sprintf(
		`{"account":{"uid":%q,"nickname":%q},"auth":{"accessToken":%q,"refreshToken":%q,"expiresAt":%d}}`,
		uid, nick, at, rt, exp))
}

// newTestEngine 起一个假桶 + 假写入通道的 Engine。
func newTestEngine(t *testing.T, fb *fakeBucket, local map[string][]byte) (*Engine, string, string) {
	t.Helper()
	dir := t.TempDir()
	authDir := filepath.Join(dir, "auths")
	dataDir := filepath.Join(dir, "data")
	for rel, content := range local {
		fp := filepath.Join(dir, rel)
		if err := os.MkdirAll(filepath.Dir(fp), 0o755); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(fp, content, 0o600); err != nil {
			t.Fatal(err)
		}
	}

	ts := httptest.NewServer(fb.handler("u/b"))
	t.Cleanup(ts.Close)

	e, err := New(Config{
		Bucket: "u/b", Endpoint: ts.URL,
		AuthDir: authDir, DataDir: dataDir,
		IncludeData: []string{"state.json"},
		Writer:      "relay", RelayURL: "http://127.0.0.1:1", // 占位，测试里换成 fakeWriter
		Timeout: "10s",
	})
	if err != nil {
		t.Fatalf("New: %v", err)
	}
	return e, authDir, dataDir
}

// TestPullDownloadsRemoteOnly 本地首次启动：桶里独有的凭证要落到本地 auths/。
func TestPullDownloadsRemoteOnly(t *testing.T) {
	fb := newFakeBucket()
	fb.put("auths/workbuddy-u1.json", authDoc("u1", "n1", "at1", "rt1", 5000), time.Now())

	e, authDir, _ := newTestEngine(t, fb, nil)
	fw := &fakeWriter{}
	e.writer = fw

	p, res, err := e.Sync(context.Background(), ModePull, false)
	if err != nil {
		t.Fatalf("Sync: %v", err)
	}
	if res.Downloaded != 1 || res.Failed != 0 {
		t.Fatalf("res=%+v plan=%+v", res, p.Actions)
	}
	raw, err := os.ReadFile(filepath.Join(authDir, "workbuddy-u1.json"))
	if err != nil {
		t.Fatalf("下载后本地文件不存在: %v", err)
	}
	if string(raw) != string(authDoc("u1", "n1", "at1", "rt1", 5000)) {
		t.Errorf("内容不一致: %s", raw)
	}
}

// TestPushUploadsLocalOnly 本地新增的账号要推到远端。
func TestPushUploadsLocalOnly(t *testing.T) {
	fb := newFakeBucket()
	e, _, _ := newTestEngine(t, fb, map[string][]byte{
		"auths/workbuddy-u2.json": authDoc("u2", "n2", "at2", "rt2", 9000),
	})
	fw := &fakeWriter{}
	e.writer = fw

	_, res, err := e.Sync(context.Background(), ModePush, false)
	if err != nil {
		t.Fatalf("Sync: %v", err)
	}
	if res.Uploaded != 1 || res.Failed != 0 {
		t.Fatalf("res=%+v", res)
	}
	got, ok := fw.written("auths/workbuddy-u2.json")
	if !ok {
		t.Fatal("远端没收到上传")
	}
	if string(got) != string(authDoc("u2", "n2", "at2", "rt2", 9000)) {
		t.Errorf("上传内容不一致: %s", got)
	}
}

// TestConflictNewerAccessTokenWins 两端都有同一账号且都刷新过 → 采用 expiresAt 更晚的一方，
// 并把赢家回灌到输家。这是"防止凭证不同步"的核心行为。
func TestConflictNewerAccessTokenWins(t *testing.T) {
	fb := newFakeBucket()
	// 远端更新（expiresAt 9000），本地陈旧（expiresAt 1000）。
	fb.put("auths/workbuddy-u3.json", authDoc("u3", "n3", "remote-at", "remote-rt", 9000), time.Now())
	e, authDir, _ := newTestEngine(t, fb, map[string][]byte{
		"auths/workbuddy-u3.json": authDoc("u3", "n3", "local-at", "local-rt", 1000),
	})
	fw := &fakeWriter{}
	e.writer = fw

	p, res, err := e.Sync(context.Background(), ModeSync, false)
	if err != nil {
		t.Fatalf("Sync: %v", err)
	}
	if len(p.Conflicts()) != 1 {
		t.Fatalf("应识别出 1 个冲突: %+v", p.Actions)
	}
	if res.Downloaded != 1 || res.Uploaded != 0 {
		t.Fatalf("应由远端覆盖本地: res=%+v", res)
	}
	raw, _ := os.ReadFile(filepath.Join(authDir, "workbuddy-u3.json"))
	if !strings.Contains(string(raw), "remote-at") {
		t.Errorf("本地未被远端覆盖: %s", raw)
	}
}

// TestConflictLocalNewerPushes 反向：本地更新 → 推到远端。
func TestConflictLocalNewerPushes(t *testing.T) {
	fb := newFakeBucket()
	fb.put("auths/workbuddy-u4.json", authDoc("u4", "n4", "remote-at", "remote-rt", 1000), time.Now())
	e, authDir, _ := newTestEngine(t, fb, map[string][]byte{
		"auths/workbuddy-u4.json": authDoc("u4", "n4", "local-at", "local-rt", 9000),
	})
	fw := &fakeWriter{}
	e.writer = fw

	_, res, err := e.Sync(context.Background(), ModeSync, false)
	if err != nil {
		t.Fatalf("Sync: %v", err)
	}
	if res.Uploaded != 1 || res.Downloaded != 0 {
		t.Fatalf("应由本地覆盖远端: res=%+v", res)
	}
	got, _ := fw.written("auths/workbuddy-u4.json")
	if !strings.Contains(string(got), "local-at") {
		t.Errorf("远端未被本地覆盖: %s", got)
	}
	raw, _ := os.ReadFile(filepath.Join(authDir, "workbuddy-u4.json"))
	if !strings.Contains(string(raw), "local-at") {
		t.Errorf("本地被误改: %s", raw)
	}
}

// TestIdenticalIsNoop 两端一致时不应产生任何读写。
func TestIdenticalIsNoop(t *testing.T) {
	doc := authDoc("u5", "n5", "at", "rt", 5000)
	fb := newFakeBucket()
	fb.put("auths/workbuddy-u5.json", doc, time.Now())
	e, _, _ := newTestEngine(t, fb, map[string][]byte{"auths/workbuddy-u5.json": doc})
	fw := &fakeWriter{}
	e.writer = fw

	p, res, err := e.Sync(context.Background(), ModeSync, false)
	if err != nil {
		t.Fatalf("Sync: %v", err)
	}
	if p.Changes() != 0 || res.Uploaded != 0 || res.Downloaded != 0 {
		t.Fatalf("一致时应无动作: plan=%+v res=%+v", p.Actions, res)
	}
}

// TestExcludedPathsNeverSynced config.json 与 request-logs 绝不能进同步范围。
func TestExcludedPathsNeverSynced(t *testing.T) {
	fb := newFakeBucket()
	fb.put("config.json", []byte(`{"listen":":7861","api_key":"relay-secret"}`), time.Now())
	fb.put("data/request-logs/requests-2026-10-02.jsonl", []byte("{}\n"), time.Now())
	fb.put("data/state.json", []byte(`{"accounts":{}}`), time.Now())

	e, authDir, dataDir := newTestEngine(t, fb, nil)
	fw := &fakeWriter{}
	e.writer = fw

	p, res, err := e.Sync(context.Background(), ModeSync, false)
	if err != nil {
		t.Fatalf("Sync: %v", err)
	}
	if res.Downloaded != 1 { // 只有 data/state.json
		t.Fatalf("应只下载 state.json: res=%+v plan=%+v", res, p.Actions)
	}
	for _, a := range p.Actions {
		if a.Path == "config.json" || strings.HasPrefix(a.Path, "data/request-logs/") {
			t.Errorf("被排除的路径出现在计划里: %+v", a)
		}
	}
	if _, err := os.Stat(filepath.Join(authDir, "..", "config.json")); err == nil {
		t.Error("config.json 被写到了本地")
	}
	if _, err := os.Stat(filepath.Join(dataDir, "request-logs")); err == nil {
		t.Error("request-logs 被同步了")
	}
}

// TestDryRunNeverWrites dry-run（status）不得产生任何落盘或上传，
// 但**必须**照常把差异算出来——漏算差异会让 status 骗人。
func TestDryRunNeverWrites(t *testing.T) {
	fb := newFakeBucket()
	fb.put("auths/workbuddy-u6.json", authDoc("u6", "n6", "at", "rt", 9000), time.Now())
	e, authDir, _ := newTestEngine(t, fb, map[string][]byte{
		"auths/workbuddy-u6.json": authDoc("u6", "n6", "old", "old", 1),
	})
	fw := &fakeWriter{}
	e.writer = fw

	plan, res, err := e.Sync(context.Background(), ModeSync, true)
	if err != nil {
		t.Fatalf("Sync: %v", err)
	}
	if plan.Changes() != 1 {
		t.Fatalf("dry-run 也必须报出这 1 处差异: %+v", plan.Actions)
	}
	if res.Downloaded != 1 { // 计入"将会做"，但没真做
		t.Fatalf("dry-run 应计入计划动作: %+v", res)
	}
	if len(fw.put) != 0 || fw.batches != 0 {
		t.Errorf("dry-run 不应上传: %+v", fw.put)
	}
	raw, _ := os.ReadFile(filepath.Join(authDir, "workbuddy-u6.json"))
	if !strings.Contains(string(raw), "old") {
		t.Errorf("dry-run 不应改本地: %s", raw)
	}
}

// TestApplyNoWriterFailsLoudly 没有写入通道时必须明确失败，不能假装成功。
func TestApplyNoWriterFailsLoudly(t *testing.T) {
	fb := newFakeBucket()
	e, _, _ := newTestEngine(t, fb, map[string][]byte{
		"auths/workbuddy-u7.json": authDoc("u7", "n7", "at", "rt", 9000),
	})
	e.writer = nil

	_, res, err := e.Sync(context.Background(), ModePush, false)
	if err != nil {
		t.Fatalf("Sync 本身不应报错: %v", err)
	}
	if res.Failed != 1 || res.Uploaded != 0 {
		t.Fatalf("应报告 1 个失败: %+v", res)
	}
}

// TestNextLink 分页 Link 头解析（含相对 URL 与多段）。
func TestNextLink(t *testing.T) {
	const ep = "https://huggingface.co"
	cases := []struct{ in, want string }{
		{"", ""},
		{`<https://huggingface.co/api/buckets/u/b/tree?cursor=2>; rel="next"`, "https://huggingface.co/api/buckets/u/b/tree?cursor=2"},
		{`</api/buckets/u/b/tree?cursor=3>; rel="next"`, ep + "/api/buckets/u/b/tree?cursor=3"},
		{`<https://x/y>; rel="prev", </api/buckets/u/b/tree?c=9>; rel="next"`, ep + "/api/buckets/u/b/tree?c=9"},
		{`<https://x/y>; rel="prev"`, ""},
		{"garbage", ""},
	}
	for _, tc := range cases {
		if got := nextLink(tc.in, ep); got != tc.want {
			t.Errorf("nextLink(%q) = %q, want %q", tc.in, got, tc.want)
		}
	}
}

// TestLocalPathRejectsTraversal localPath 必须挡住越界路径。
func TestLocalPathRejectsTraversal(t *testing.T) {
	e := &Engine{cfg: Config{AuthDir: "/tmp/a", DataDir: "/tmp/d", IncludeData: []string{"state.json"}}}
	for _, bad := range []string{"config.json", "../evil.json", "auths/../../evil.json", "other/x.json"} {
		if _, err := e.localPath(bad); err == nil {
			t.Errorf("localPath(%q) 应报错", bad)
		}
	}
	if fp, err := e.localPath("auths/workbuddy-1.json"); err != nil || !strings.HasSuffix(fp, "workbuddy-1.json") {
		t.Errorf("localPath 正常路径失败: %q %v", fp, err)
	}
}

// TestJSONOutputNeverLeaksCredentialMaterial 安全回归：FileState.Content 绝不能被序列化出去。
//
// Action 会被 `wb2api-sync -json` 整个打印，Content 一旦进 JSON，`status -json`
// 就会把 accessToken / refreshToken 明文（原始与 base64 两种形态）灌进终端、
// CI 日志或 issue 附件——等于自己把凭证泄露出去。实测早期版本正是这样泄露的。
func TestJSONOutputNeverLeaksCredentialMaterial(t *testing.T) {
	const secret = "SUPER-SECRET-REFRESH-TOKEN-VALUE"
	doc := authDoc("u1", "nick", "access-"+secret, "refresh-"+secret, 9000)
	st := newFileState("auths/workbuddy-u1.json", doc, time.Now(), catAuth)
	if st.Content == nil {
		t.Fatal("夹具前提不成立：Content 应为原始字节")
	}
	if !strings.Contains(string(st.Content), secret) {
		t.Fatal("夹具前提不成立：内容里应含 secret")
	}

	raw, err := json.Marshal(Action{Op: OpDownload, Path: st.Path, Category: catAuth, Local: st, Remote: st})
	if err != nil {
		t.Fatal(err)
	}
	got := string(raw)
	if strings.Contains(got, secret) {
		t.Fatalf("JSON 里出现了凭证明文: %s", got)
	}
	if strings.Contains(strings.ToLower(got), `"content"`) {
		t.Errorf("JSON 里出现了 content 字段: %s", got)
	}
	b64 := base64.StdEncoding.EncodeToString(doc)
	if len(b64) > 24 && strings.Contains(got, b64[:24]) {
		t.Errorf("JSON 里出现了 content 的 base64 前缀: %s", got)
	}
	// 该有的诊断字段不能因为脱敏一起丢掉。
	if !strings.Contains(got, st.SHA256) || !strings.Contains(got, "u1") {
		t.Errorf("SHA256/UID 等诊断字段应保留: %s", got)
	}
}