package qq_obv11

import (
	"errors"
	"strconv"
	"testing"
	"time"
)

const rlKeyA = "qq-obv11|100|100"

func TestRateLimiterAllowWithinWindow(t *testing.T) {
	t.Parallel()

	rl := newRateLimiter(3, 10*time.Second)
	now := time.Now()
	for i := 0; i < 3; i++ {
		if !rl.allow(rlKeyA, now) {
			t.Fatalf("allow #%d denied, want allowed", i)
		}
	}
	if rl.allow(rlKeyA, now) {
		t.Error("4th allow in window accepted, want denied")
	}
}

func TestRateLimiterDeniedOverWindow(t *testing.T) {
	t.Parallel()

	rl := newRateLimiter(2, 10*time.Second)
	base := time.Now()
	if !rl.allow(rlKeyA, base) || !rl.allow(rlKeyA, base) {
		t.Fatal("first two sends should be allowed")
	}
	if rl.allow(rlKeyA, base) {
		t.Error("third send within window allowed, want denied")
	}
	// After the window elapses, the budget frees up.
	if !rl.allow(rlKeyA, base.Add(11*time.Second)) {
		t.Error("send after window elapsed denied, want allowed")
	}
}

// TestRateLimiterSessionsIndependent 是裁决 06.4.3 的断言：额度按会话（群聊/私聊）
// 独立计数，一个群用尽自己的额度不会挤占另一个群，也不影响私聊。
func TestRateLimiterSessionsIndependent(t *testing.T) {
	t.Parallel()

	rl := newRateLimiter(2, 10*time.Second)
	now := time.Now()
	const (
		groupB = "qq-obv11|200|200"
		peer   = "qq-obv11|900|900"
	)

	for i := 0; i < 2; i++ {
		if !rl.allow(rlKeyA, now) {
			t.Fatalf("group A send #%d denied, want allowed", i+1)
		}
	}
	if rl.allow(rlKeyA, now) {
		t.Fatal("group A exceeded its own quota, want denied")
	}
	for i := 0; i < 2; i++ {
		if !rl.allow(groupB, now) {
			t.Fatalf("group B send #%d denied by group A's quota — 会话计数未隔离", i+1)
		}
		if !rl.allow(peer, now) {
			t.Fatalf("peer send #%d denied by another session's quota — 会话计数未隔离", i+1)
		}
	}
}

// TestRateLimiterPrunesIdleSessions 保证长跑进程里会话键不会无界增长：键数超过阈值后，
// 窗口内已无记录的会话会被回收，新会话照常放行。
func TestRateLimiterPrunesIdleSessions(t *testing.T) {
	t.Parallel()

	rl := newRateLimiter(1, 10*time.Second)
	base := time.Now()
	for i := 0; i < sendSessionsGCThreshold+1; i++ {
		if !rl.allow("sess-"+strconv.Itoa(i), base) {
			t.Fatalf("session %d denied, want allowed", i)
		}
	}
	later := base.Add(time.Minute)
	if !rl.allow("fresh", later) {
		t.Fatal("fresh session denied after window roll")
	}
	rl.mu.Lock()
	keys := len(rl.times)
	rl.mu.Unlock()
	if keys > sendSessionsGCThreshold {
		t.Fatalf("idle sessions not pruned: %d keys remain", keys)
	}
}

func TestRateLimiterDisabledAllowsAll(t *testing.T) {
	t.Parallel()

	rl := newRateLimiter(0, 10*time.Second)
	for i := 0; i < 100; i++ {
		if !rl.allow(rlKeyA, time.Now()) {
			t.Fatalf("disabled limiter denied send #%d", i)
		}
	}
}

func TestRateLimiterNilAllows(t *testing.T) {
	t.Parallel()

	var rl *rateLimiter
	if !rl.allow(rlKeyA, time.Now()) {
		t.Error("nil limiter denied send, want allowed")
	}
}

func TestErrRateLimitedSentinel(t *testing.T) {
	t.Parallel()

	if !errors.Is(ErrRateLimited, ErrRateLimited) {
		t.Error("ErrRateLimited should be its own sentinel")
	}
}