package handlers

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"github.com/gin-gonic/gin"
)

func init() {
	gin.SetMode(gin.TestMode)
}

// fakeDeviceLister 是 deviceLister 的測試替身。
type fakeDeviceLister struct {
	serials []string
}

func (f fakeDeviceLister) ListDevices() []deviceInfoView {
	out := make([]deviceInfoView, 0, len(f.serials))
	for _, s := range f.serials {
		out = append(out, deviceInfoView{SerialNumber: s})
	}
	return out
}

// fakeStore 是 localTokenStore 的測試替身。
type fakeStore struct {
	token     string
	expiresAt time.Time
	err       error
	isLimit   bool
	gotDevice string
}

func (f *fakeStore) Issue(deviceID string) (string, time.Time, error) {
	f.gotDevice = deviceID
	return f.token, f.expiresAt, f.err
}

func (f *fakeStore) IsLimitErr(err error) bool { return f.isLimit && err != nil }

// expectedHash 用測試獨立的實作重算 SHA-256(salt||serial) hex，
// 避免直接呼叫被測函式（防同一個 bug 同時存在於實作與預期）。
func expectedHash(serial string) string {
	sum := sha256.Sum256([]byte("visiona-local-v1" + serial))
	return hex.EncodeToString(sum[:])
}

// TestHello_SerialHashes：hello 回 serialHashes（正確 hex）+ supportsLocalUpload，
// 跳過空 / fake 序號，且不回 agentVersion / 完整 serial。
func TestHello_SerialHashes(t *testing.T) {
	h := &LocalHandler{
		devices: fakeDeviceLister{serials: []string{
			"0x1A2B3C4D",
			"",           // 空 → 跳過
			"0x00000000", // fake placeholder → 跳過
			"0xDEADBEEF",
		}},
	}

	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)
	c.Request = httptest.NewRequest(http.MethodGet, "/api/local/hello", nil)
	h.Hello(c)

	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", w.Code)
	}

	var resp struct {
		Success bool `json:"success"`
		Data    struct {
			SerialHashes        []string `json:"serialHashes"`
			SupportsLocalUpload bool     `json:"supportsLocalUpload"`
		} `json:"data"`
	}
	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
		t.Fatalf("decode: %v", err)
	}

	if !resp.Success {
		t.Error("success 應為 true")
	}
	if !resp.Data.SupportsLocalUpload {
		t.Error("supportsLocalUpload 應為 true")
	}
	// 只應有兩個真實序號的 hash
	if len(resp.Data.SerialHashes) != 2 {
		t.Fatalf("serialHashes 數量 = %d, want 2（空與 fake 應被跳過）", len(resp.Data.SerialHashes))
	}
	wantSet := map[string]bool{
		expectedHash("0x1A2B3C4D"): true,
		expectedHash("0xDEADBEEF"): true,
	}
	for _, got := range resp.Data.SerialHashes {
		if !wantSet[got] {
			t.Errorf("非預期的 hash: %q", got)
		}
		// hex 必須是 lowercase、長度 64（SHA-256 = 32 bytes → 64 hex chars）
		if len(got) != 64 {
			t.Errorf("hash 長度 = %d, want 64", len(got))
		}
		if got != strings.ToLower(got) {
			t.Errorf("hash 必須 lowercase hex，got %q", got)
		}
	}

	// 最小揭露：不得出現 agentVersion / 完整 serial 明文
	bodyStr := w.Body.String()
	if strings.Contains(bodyStr, "agentVersion") {
		t.Error("hello 不應回 agentVersion")
	}
	if strings.Contains(bodyStr, "0x1A2B3C4D") || strings.Contains(bodyStr, "0xDEADBEEF") {
		t.Error("hello 不應回完整 serial 明文")
	}
}

// TestHello_EmptyDevices：無裝置 → serialHashes 為空陣列（非 null）。
func TestHello_EmptyDevices(t *testing.T) {
	h := &LocalHandler{devices: fakeDeviceLister{serials: nil}}
	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)
	c.Request = httptest.NewRequest(http.MethodGet, "/api/local/hello", nil)
	h.Hello(c)

	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", w.Code)
	}
	if !strings.Contains(w.Body.String(), `"serialHashes":[]`) {
		t.Errorf("空裝置應回 serialHashes:[]，got %s", w.Body.String())
	}
}

// TestHashSerial_Contract 直接驗證被測 hashSerial 的字串拼接 / 編碼 / hex 大小寫
// 與前端逐 byte 一致性複核需要的契約：SHA-256("visiona-local-v1"||serial) lowercase hex。
func TestHashSerial_Contract(t *testing.T) {
	serial := "0x1A2B3C4D"
	got := hashSerial(serial)
	want := expectedHash(serial)
	if got != want {
		t.Errorf("hashSerial(%q) = %q, want %q", serial, got, want)
	}
	// 明確固定一個已知向量，供前端對照（salt+serial 直接字串相接、UTF-8、SHA-256、lowercase hex）
	// echo -n "visiona-local-v10x1A2B3C4D" | shasum -a 256
	if len(got) != 64 || got != strings.ToLower(got) {
		t.Errorf("hex 格式不符：len=%d lower=%v", len(got), got == strings.ToLower(got))
	}
	if LocalSerialSalt != "visiona-local-v1" {
		t.Errorf("LocalSerialSalt = %q, want visiona-local-v1（前後端共用常數）", LocalSerialSalt)
	}
}

// TestIssueToken_Success：正常發放 → 200 + token/expiresAt/ttlSeconds，deviceId 綁 serial。
func TestIssueToken_Success(t *testing.T) {
	exp := time.UnixMilli(1_700_000_000_000)
	store := &fakeStore{token: "tok-xyz", expiresAt: exp}
	h := &LocalHandler{store: store}

	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)
	c.Request = httptest.NewRequest(http.MethodPost, "/api/local/issue-token",
		strings.NewReader(`{"serial":"0xAAAA0001"}`))
	c.Request.Header.Set("Content-Type", "application/json")
	h.IssueToken(c)

	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200 (body=%s)", w.Code, w.Body.String())
	}
	var resp struct {
		Data struct {
			Token      string `json:"token"`
			ExpiresAt  int64  `json:"expiresAt"`
			TTLSeconds int    `json:"ttlSeconds"`
		} `json:"data"`
	}
	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if resp.Data.Token != "tok-xyz" {
		t.Errorf("token = %q, want tok-xyz", resp.Data.Token)
	}
	if resp.Data.ExpiresAt != exp.UnixMilli() {
		t.Errorf("expiresAt = %d, want %d", resp.Data.ExpiresAt, exp.UnixMilli())
	}
	if resp.Data.TTLSeconds != 120 {
		t.Errorf("ttlSeconds = %d, want 120", resp.Data.TTLSeconds)
	}
	if store.gotDevice != "0xAAAA0001" {
		t.Errorf("Issue deviceID = %q, want 0xAAAA0001（token 綁 serial）", store.gotDevice)
	}
}

// TestIssueToken_Limit：達上限 → 429 LOCAL_TOKEN_LIMIT。
func TestIssueToken_Limit(t *testing.T) {
	store := &fakeStore{err: errors.New("limit"), isLimit: true}
	h := &LocalHandler{store: store}

	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)
	c.Request = httptest.NewRequest(http.MethodPost, "/api/local/issue-token",
		strings.NewReader(`{"serial":"0xAAAA0001"}`))
	c.Request.Header.Set("Content-Type", "application/json")
	h.IssueToken(c)

	if w.Code != http.StatusTooManyRequests {
		t.Fatalf("status = %d, want 429", w.Code)
	}
	if !strings.Contains(w.Body.String(), "LOCAL_TOKEN_LIMIT") {
		t.Errorf("body 應含 LOCAL_TOKEN_LIMIT，got %s", w.Body.String())
	}
}

// TestIssueToken_MissingSerial：缺 serial → 400。
func TestIssueToken_MissingSerial(t *testing.T) {
	h := &LocalHandler{store: &fakeStore{}}
	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)
	c.Request = httptest.NewRequest(http.MethodPost, "/api/local/issue-token",
		strings.NewReader(`{}`))
	c.Request.Header.Set("Content-Type", "application/json")
	h.IssueToken(c)

	if w.Code != http.StatusBadRequest {
		t.Fatalf("status = %d, want 400", w.Code)
	}
}