package events

// 本文件是**计数面**的验收（design/26 §4.1 表二 + §4.3；切片 E1）。三条不变量在这里
// 各自有对应用例：**有界**（缓冲满即落盘、绝不无界增长）、**尽力而为**（落盘失败
// 不上抛、不丢帧）、**近似值语义**（读的是已落盘的表，不是内存里的实时值）。

import (
	"context"
	"fmt"
	"testing"
	"time"
)

// TestCounters_BoundedBuffer_边界：缓冲设上界后，**必须**在满时整批落盘，且待落盘
// 键数在任何时刻都不超过上界（design/26 §4.3 的背压；对齐 AGENTS §10 压测纪律的
// 「有界」）。同时验证落盘不是「丢计数」：最终总数与录制条数一致。
func TestCounters_BoundedBuffer_边界(t *testing.T) {
	t.Parallel()
	ctx := context.Background()
	const maxKeys = 4
	st, _ := newTestStore(t, func(cfg *Config) { cfg.MaxPendingKeys = maxKeys })

	const frames = 20
	for i := 0; i < frames; i++ {
		if err := st.Record(ctx, Event{
			Platform:     PlatformQQ,
			Tier:         TierT1,
			Category:     CategoryHeartbeat,
			PlatformType: fmt.Sprintf("type-%02d", i),
		}); err != nil {
			t.Fatalf("Record(#%d): %v", i, err)
		}
		if got := st.PendingKeys(); got > maxKeys {
			t.Fatalf("PendingKeys = %d after frame #%d, want ≤ %d（缓冲必须有界）", got, i, maxKeys)
		}
	}

	// 「有界」的直接推论：这一路必须**已经落过盘**（否则内存里会攒着 20 个键）。
	flushed, err := st.Counters(ctx, PlatformQQ)
	if err != nil {
		t.Fatalf("Counters: %v", err)
	}
	if len(flushed) == 0 {
		t.Fatal("no counters flushed to the database: a bounded buffer must flush when full")
	}

	// 落盘 = 计数搬家而不是丢掉：最后一次 flush 后总数必须恰为 frames。
	if err := st.Flush(ctx); err != nil {
		t.Fatalf("Flush: %v", err)
	}
	var total int64
	for _, c := range mustCounters(t, st, PlatformQQ) {
		total += c.Count
	}
	if total != frames {
		t.Fatalf("flushed count total = %d, want %d", total, frames)
	}
	if got := st.PendingKeys(); got != 0 {
		t.Fatalf("PendingKeys = %d after Flush, want 0", got)
	}
}

// TestCounters_FlushFailureStaysBounded_异常：数据库不可用时，计数落盘失败只记 WARN、
// **不上抛**（Record 仍返回 nil —— 计数是尽力而为，绝不让入站流水线失败，§4.3），
// 并且缓冲**仍然有界**（绝不因为一直失败而无界增长）。
func TestCounters_FlushFailureStaysBounded_异常(t *testing.T) {
	t.Parallel()
	ctx := context.Background()
	const maxKeys = 2
	st, conn := newTestStore(t, func(cfg *Config) { cfg.MaxPendingKeys = maxKeys })
	if err := conn.Close(); err != nil {
		t.Fatalf("关闭内存库: %v", err)
	}

	for i := 0; i < 5; i++ {
		if err := st.Record(ctx, Event{
			Platform:     PlatformQQ,
			Tier:         TierT1,
			Category:     CategoryHeartbeat,
			PlatformType: fmt.Sprintf("type-%02d", i),
		}); err != nil {
			t.Fatalf("Record(#%d) err = %v, want nil（计数失败绝不能上抛）", i, err)
		}
		if got := st.PendingKeys(); got > maxKeys {
			t.Fatalf("PendingKeys = %d after failing flush #%d, want ≤ %d", got, i, maxKeys)
		}
	}
	if got := st.PendingKeys(); got != maxKeys {
		t.Fatalf("PendingKeys = %d, want %d (失败项回填后仍受上界约束)", got, maxKeys)
	}
}

// TestCounters_SameKeyAccumulates_正常：同一个键（平台+账号+原生类型）反复计数是
// **累加同一行**，且 tier/category 首次权威、first/last_seen_at 如实推进。
func TestCounters_SameKeyAccumulates_正常(t *testing.T) {
	t.Parallel()
	ctx := context.Background()
	st, _ := newTestStore(t, nil)

	ev := Event{
		Platform:     PlatformQQ,
		AccountID:    "bot-1",
		Tier:         TierT1,
		Category:     CategoryHeartbeat,
		PlatformType: "heartbeat",
	}
	for i := 0; i < 3; i++ {
		if err := st.Record(ctx, ev); err != nil {
			t.Fatalf("Record(#%d): %v", i, err)
		}
	}
	if err := st.Flush(ctx); err != nil {
		t.Fatalf("Flush: %v", err)
	}

	later := ev
	later.CreatedAt = testNow().Add(time.Minute)
	for i := 0; i < 2; i++ {
		if err := st.Record(ctx, later); err != nil {
			t.Fatalf("Record(later #%d): %v", i, err)
		}
	}
	if err := st.Flush(ctx); err != nil {
		t.Fatalf("Flush: %v", err)
	}

	rows := mustCounters(t, st, PlatformQQ)
	if len(rows) != 1 {
		t.Fatalf("counter rows = %d, want 1 (同键必须合并)", len(rows))
	}
	got := rows[0]
	if got.Count != 5 {
		t.Fatalf("count = %d, want 5 (3 + 2)", got.Count)
	}
	if !got.FirstSeenAt.Equal(testNow()) {
		t.Fatalf("first_seen_at = %v, want %v (首次权威)", got.FirstSeenAt, testNow())
	}
	if !got.LastSeenAt.Equal(later.CreatedAt) {
		t.Fatalf("last_seen_at = %v, want %v", got.LastSeenAt, later.CreatedAt)
	}
	if got.AccountID != "bot-1" || got.PlatformType != "heartbeat" {
		t.Fatalf("key columns = (%q, %q), want (bot-1, heartbeat)", got.AccountID, got.PlatformType)
	}
}

// TestCounters_PlatformFilter_正常：Counters 的 platform 参数为空表示全部平台，
// 非空即精确过滤（design/26 §4.5 的查询参数语义）。
func TestCounters_PlatformFilter_正常(t *testing.T) {
	t.Parallel()
	ctx := context.Background()
	st, _ := newTestStore(t, nil)

	for _, platform := range []string{PlatformQQ, PlatformKook} {
		if err := st.Record(ctx, Event{
			Platform: platform, Tier: TierT1, Category: CategoryHeartbeat, PlatformType: "heartbeat",
		}); err != nil {
			t.Fatalf("Record(%s): %v", platform, err)
		}
	}
	if err := st.Flush(ctx); err != nil {
		t.Fatalf("Flush: %v", err)
	}

	if rows := mustCounters(t, st, ""); len(rows) != 2 {
		t.Fatalf("all platforms = %d rows, want 2", len(rows))
	}
	rows := mustCounters(t, st, PlatformKook)
	if len(rows) != 1 || rows[0].Platform != PlatformKook {
		t.Fatalf("filtered rows = %+v, want exactly the kook counter", rows)
	}
	if rows := mustCounters(t, st, PlatformTelegram); len(rows) != 0 {
		t.Fatalf("unknown platform = %d rows, want 0", len(rows))
	}
}

// TestCounters_PendingNotVisibleBeforeFlush_边界：Counters 读的是**已落盘**的表 ——
// 这正是「计数为近似值」的来源（design/26 §4.3/§4.5），查询面必须如实标注。
func TestCounters_PendingNotVisibleBeforeFlush_边界(t *testing.T) {
	t.Parallel()
	ctx := context.Background()
	st, _ := newTestStore(t, nil)

	if err := st.Record(ctx, Event{
		Platform: PlatformQQ, Tier: TierT1, Category: CategoryHeartbeat, PlatformType: "heartbeat",
	}); err != nil {
		t.Fatalf("Record: %v", err)
	}
	if rows := mustCounters(t, st, PlatformQQ); len(rows) != 0 {
		t.Fatalf("rows before Flush = %d, want 0（内存计数不算已落盘）", len(rows))
	}
	if st.PendingKeys() != 1 {
		t.Fatalf("PendingKeys = %d, want 1", st.PendingKeys())
	}
	if err := st.Flush(ctx); err != nil {
		t.Fatalf("Flush: %v", err)
	}
	if rows := mustCounters(t, st, PlatformQQ); len(rows) != 1 {
		t.Fatalf("rows after Flush = %d, want 1", len(rows))
	}
}

// mustCounters 是 Counters 的测试包装（失败即 Fatal）。
func mustCounters(t *testing.T, st *SQLStore, platform string) []Counter {
	t.Helper()
	rows, err := st.Counters(context.Background(), platform)
	if err != nil {
		t.Fatalf("Counters(%q): %v", platform, err)
	}
	return rows
}