// Copyright 2022 E99p1ant. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package stats

import (
	"strings"
	"testing"
	"time"

	"github.com/stretchr/testify/require"

	"github.com/tamakyi/TamaBox/internal/db"
)

// TestBuildDailyFillsGaps 没有数据的日期必须占位，否则折线会把两天连成一条直线，
// 让人以为「那天也有提问」。
func TestBuildDailyFillsGaps(t *testing.T) {
	now := time.Date(2026, 10, 23, 15, 30, 0, 0, time.Local)
	got := buildDaily([]db.CountPoint{{Key: "2026-10-20", N: 5}}, now, 5)

	require.Len(t, got, 5)
	require.Equal(t, "2026-10-19", got[0].Date)
	require.Equal(t, "2026-10-23", got[4].Date)
	require.EqualValues(t, 0, got[0].N)
	require.EqualValues(t, 5, got[1].N, "10-20 是窗口里的第 2 天")
}

// TestBuildMonthlyNoMonthOverflow 月底不能溢出：3-31 直接 AddDate(0,-11,0) 会滚到 3 月初，
// 12 根柱子就变成 11 根。实现里先归到当月 1 号，这里守住这个行为。
func TestBuildMonthlyNoMonthOverflow(t *testing.T) {
	now := time.Date(2026, 3, 31, 0, 0, 0, 0, time.Local)
	got := buildMonthly(nil, now, 12)

	require.Len(t, got, 12)
	require.Equal(t, "2025-04", got[0].Month)
	require.Equal(t, "2026-03", got[11].Month)
	require.True(t, got[11].Current, "最后一根柱子是当月")
	require.False(t, got[0].Current)
}

// TestBusiestSlot 同值时取更早的下标，保证同一份数据每次算出来的结论一致。
func TestBusiestSlot(t *testing.T) {
	var heatmap [7][24]int64
	heatmap[2][9] = 10
	heatmap[5][20] = 10

	wd, hr := busiestSlot(heatmap)
	require.Equal(t, 2, wd)
	require.Equal(t, 9, hr)
}

// TestOverviewEmptyNoDivideByZero 全零数据不能除零，也不能编出不存在的结论。
func TestOverviewEmptyNoDivideByZero(t *testing.T) {
	v := buildOverview(&db.SiteAnalytics{}, time.Now())

	require.Zero(t, v.AnswerRate)
	require.Zero(t, v.FastReplyRate)
	require.Zero(t, v.GrowthMoM)
	require.False(t, v.HasPrevMonth)
	require.Len(t, v.Daily, dailyWindowDays)
	require.Len(t, v.Monthly, monthlyWindow)

	page := NewPage("zh-CN", v)
	require.Len(t, page.Insights, 1, "空库只说一句「数据还太少」")
	require.Equal(t, "提问数据还太少，暂时看不出什么。", page.Insights[0])
}

// TestOverviewDerived 派生指标：回答率、环比、最忙时段、24 小时内回复占比。
func TestOverviewDerived(t *testing.T) {
	now := time.Now()
	monthStart := time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, now.Location())
	prevMonth := monthStart.AddDate(0, -1, 0).Format("2006-01")
	monthBefore := monthStart.AddDate(0, -2, 0).Format("2006-01")

	raw := &db.SiteAnalytics{
		TotalQuestions: 200, Answered: 50, Private: 20,
		Anonymous: 120,
		Daily:     []db.CountPoint{{Key: now.Format("2006-01-02"), N: 7}},
		// 环比看的是「上月」与「上上月」：本月还没过完，当年 10 月为 0 会把结论带偏。
		Monthly: []db.CountPoint{
			{Key: monthBefore, N: 100},
			{Key: prevMonth, N: 50},
		},
		LengthBins: [6]int64{1, 2, 3, 4, 5, 6},
		ReplyBins:  [6]int64{10, 10, 10, 10, 5, 5},
	}
	raw.Heatmap[1][8] = 40

	v := buildOverview(raw, now)

	require.InDelta(t, 25.0, v.AnswerRate, 0.001)
	require.InDelta(t, 60.0, v.FastReplyRate, 0.001, "(10+10+10)/50 在 24 小时内")
	require.Equal(t, 180, int(v.Public))
	require.Equal(t, 80, int(v.LoggedIn))
	require.Equal(t, 1, v.BusiestWD)
	require.Equal(t, 8, v.BusiestHr)
	require.EqualValues(t, 40, v.HeatmapMax)
	require.True(t, v.HasPrevMonth)
	require.InDelta(t, -50.0, v.GrowthMoM, 0.001, "9 月 50 相对 8 月 100 是 -50%")

	page := NewPage("zh-CN", v)
	require.NotEmpty(t, page.Insights)
	require.Len(t, page.WeekdayLabels, 7)
	require.Len(t, page.LengthLabels, 6)
	require.Len(t, page.ReplyLabels, 6)

	// 句子里必须是完整星期名：热力图列头的 stats.wd.* 是单字（"一"/"三"），
	// 复用到句子里会读成「提问最集中在三 8 点前后」。
	require.Contains(t, strings.Join(page.Insights, "\n"), "提问最集中在周一 8 点前后。")
}