package main

import (
	"bytes"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"path/filepath"
	"testing"
)

// 复现「访问次数被平方级放大」：扩展每 30s 上报一次该 URL 的
// chrome.history.search visitCount —— 那是**绝对累计值**（1,2,3,4,5…），
// 而 handleSync 用 `e.TotalVisits += item.VisitCount` 把它当增量累加。
// 结果 5 次真实访问被记成 15 次。
func TestSyncDoubleCountsAbsoluteVisitCount(t *testing.T) {
	dir := t.TempDir()
	oldDir, oldFile, oldTok := dataDir, historyFile, syncToken
	dataDir = dir
	historyFile = filepath.Join(dir, "history.json")
	syncToken = "t"
	defer func() { dataDir, historyFile, syncToken = oldDir, oldFile, oldTok }()

	history = map[string]*Entry{}

	// 模拟 5 轮同步：同一 URL 的绝对 visitCount 依次为 1..5
	for round, vc := range []int{1, 2, 3, 4, 5} {
		body, _ := json.Marshal(SyncRequest{Items: []SyncItem{{
			URL: "https://ex.com/a", Title: "A", Device: "desktop",
			Timestamp: float64(1700000000 + round*30), VisitCount: vc,
		}}})
		req := httptest.NewRequest(http.MethodPost, "/sync", bytes.NewReader(body))
		req.Header.Set("Authorization", "Bearer t")
		w := httptest.NewRecorder()
		handleSync(w, req)
		if w.Code != http.StatusOK {
			t.Fatalf("round %d: status = %d", round, w.Code)
		}
	}

	e := history["https://ex.com/a"]
	if e == nil {
		t.Fatal("entry not created")
	}
	t.Logf("真实访问 5 次 → 落盘 TotalVisits = %d", e.TotalVisits)
	if e.TotalVisits != 5 {
		t.Errorf("TotalVisits = %d; 真实只访问 5 次，被平方级放大（期望 5）", e.TotalVisits)
	}
}

// 上报 100 次同一 URL 会放大到什么程度 —— 量化后果。
func TestSyncInflationScalesQuadratically(t *testing.T) {
	dir := t.TempDir()
	oldDir, oldFile, oldTok := dataDir, historyFile, syncToken
	dataDir = dir
	historyFile = filepath.Join(dir, "history.json")
	syncToken = "t"
	defer func() { dataDir, historyFile, syncToken = oldDir, oldFile, oldTok }()

	history = map[string]*Entry{}
	// 真实访问 30 次，但扩展每 30s 同步一次 → 上报 30 次绝对值
	for round := 1; round <= 30; round++ {
		body, _ := json.Marshal(SyncRequest{Items: []SyncItem{{
			URL: "https://ex.com/b", Device: "desktop",
			Timestamp: float64(1700000000 + round*30), VisitCount: round,
		}}})
		req := httptest.NewRequest(http.MethodPost, "/sync", bytes.NewReader(body))
		req.Header.Set("Authorization", "Bearer t")
		handleSync(httptest.NewRecorder(), req)
	}
	got := history["https://ex.com/b"].TotalVisits
	want := 30
	t.Logf("真实 30 次访问 → 落盘 %d 次（虚高 %.1f×）", got, float64(got)/float64(want))
	if got != want {
		t.Errorf("TotalVisits = %d; want %d", got, want)
	}
}