package main

import (
	"bufio"
	"fmt"
	"os"
	"regexp"
	"strings"
	"sync"
	"testing"
	"time"
)

// TestConcurrentStressLogger 高并发压力测试
func TestConcurrentStressLogger(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping stress test in short mode")
	}

	logger, err := NewLoggerWithSuffix("stress")
	if err != nil {
		t.Fatal(err)
	}
	defer logger.Close()

	t.Logf("Log file: %s", logger.Path())

	const (
		numGoroutines  = 100  // 并发协程数
		logsPerRoutine = 1000 // 每个协程写入日志数
		totalExpected  = numGoroutines * logsPerRoutine
	)

	var wg sync.WaitGroup
	start := time.Now()

	// 启动并发写入
	for i := 0; i < numGoroutines; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()
			for j := 0; j < logsPerRoutine; j++ {
				logger.Info(fmt.Sprintf("goroutine-%d-msg-%d", id, j))
			}
		}(i)
	}

	wg.Wait()
	logger.Flush()
	elapsed := time.Since(start)

	// 读取日志文件验证
	data, err := os.ReadFile(logger.Path())
	if err != nil {
		t.Fatalf("failed to read log file: %v", err)
	}

	lines := strings.Split(strings.TrimSpace(string(data)), "\n")
	actualCount := len(lines)

	t.Logf("Concurrent stress test results:")
	t.Logf("  Goroutines: %d", numGoroutines)
	t.Logf("  Logs per goroutine: %d", logsPerRoutine)
	t.Logf("  Total expected: %d", totalExpected)
	t.Logf("  Total actual: %d", actualCount)
	t.Logf("  Duration: %v", elapsed)
	t.Logf("  Throughput: %.2f logs/sec", float64(totalExpected)/elapsed.Seconds())

	// 验证日志数量
	if actualCount < totalExpected/10 {
		t.Errorf("too many logs lost: got %d, want at least %d (10%% of %d)",
			actualCount, totalExpected/10, totalExpected)
	}
	t.Logf("Successfully wrote %d/%d logs (%.1f%%)",
		actualCount, totalExpected, float64(actualCount)/float64(totalExpected)*100)

	// 验证日志格式
	formatRE := regexp.MustCompile(`^\[\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}\.\d{3}\] \[PID:\d+\] INFO: goroutine-`)
	for i, line := range lines[:min(10, len(lines))] {
		if !formatRE.MatchString(line) {
			t.Errorf("line %d has invalid format: %s", i, line)
		}
	}
}

// TestConcurrentBurstLogger 突发流量测试
func TestConcurrentBurstLogger(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping burst test in short mode")
	}

	logger, err := NewLoggerWithSuffix("burst")
	if err != nil {
		t.Fatal(err)
	}
	defer logger.Close()

	t.Logf("Log file: %s", logger.Path())

	const (
		numBursts          = 10
		goroutinesPerBurst = 50
		logsPerGoroutine   = 100
	)

	totalLogs := 0
	start := time.Now()

	// 模拟突发流量
	for burst := 0; burst < numBursts; burst++ {
		var wg sync.WaitGroup
		for i := 0; i < goroutinesPerBurst; i++ {
			wg.Add(1)
			totalLogs += logsPerGoroutine
			go func(b, g int) {
				defer wg.Done()
				for j := 0; j < logsPerGoroutine; j++ {
					logger.Info(fmt.Sprintf("burst-%d-goroutine-%d-msg-%d", b, g, j))
				}
			}(burst, i)
		}
		wg.Wait()
		time.Sleep(10 * time.Millisecond) // 突发间隔
	}

	logger.Flush()
	elapsed := time.Since(start)

	// 验证
	data, err := os.ReadFile(logger.Path())
	if err != nil {
		t.Fatalf("failed to read log file: %v", err)
	}

	lines := strings.Split(strings.TrimSpace(string(data)), "\n")
	actualCount := len(lines)

	t.Logf("Burst test results:")
	t.Logf("  Total bursts: %d", numBursts)
	t.Logf("  Goroutines per burst: %d", goroutinesPerBurst)
	t.Logf("  Expected logs: %d", totalLogs)
	t.Logf("  Actual logs: %d", actualCount)
	t.Logf("  Duration: %v", elapsed)
	t.Logf("  Throughput: %.2f logs/sec", float64(totalLogs)/elapsed.Seconds())

	if actualCount < totalLogs/10 {
		t.Errorf("too many logs lost: got %d, want at least %d (10%% of %d)", actualCount, totalLogs/10, totalLogs)
	}
	t.Logf("Successfully wrote %d/%d logs (%.1f%%)",
		actualCount, totalLogs, float64(actualCount)/float64(totalLogs)*100)
}

// TestLoggerChannelCapacity 测试 channel 容量极限
func TestLoggerChannelCapacity(t *testing.T) {
	logger, err := NewLoggerWithSuffix("capacity")
	if err != nil {
		t.Fatal(err)
	}
	defer logger.Close()

	const rapidLogs = 2000 // 超过 channel 容量 (1000)

	start := time.Now()
	for i := 0; i < rapidLogs; i++ {
		logger.Info(fmt.Sprintf("rapid-log-%d", i))
	}
	sendDuration := time.Since(start)

	logger.Flush()
	flushDuration := time.Since(start) - sendDuration

	t.Logf("Channel capacity test:")
	t.Logf("  Logs sent: %d", rapidLogs)
	t.Logf("  Send duration: %v", sendDuration)
	t.Logf("  Flush duration: %v", flushDuration)

	// 验证仍有合理比例的日志写入（非阻塞模式允许部分丢失）
	data, err := os.ReadFile(logger.Path())
	if err != nil {
		t.Fatal(err)
	}
	lines := strings.Split(strings.TrimSpace(string(data)), "\n")
	actualCount := len(lines)

	if actualCount < rapidLogs/10 {
		t.Errorf("too many logs lost: got %d, want at least %d (10%% of %d)", actualCount, rapidLogs/10, rapidLogs)
	}
	t.Logf("Logs persisted: %d/%d (%.1f%%)", actualCount, rapidLogs, float64(actualCount)/float64(rapidLogs)*100)
}

// TestLoggerMemoryUsage 内存使用测试
func TestLoggerMemoryUsage(t *testing.T) {
	logger, err := NewLoggerWithSuffix("memory")
	if err != nil {
		t.Fatal(err)
	}
	defer logger.Close()

	const numLogs = 20000
	longMessage := strings.Repeat("x", 500) // 500 字节长消息

	start := time.Now()
	for i := 0; i < numLogs; i++ {
		logger.Info(fmt.Sprintf("log-%d-%s", i, longMessage))
	}
	logger.Flush()
	elapsed := time.Since(start)

	// 检查文件大小
	info, err := os.Stat(logger.Path())
	if err != nil {
		t.Fatal(err)
	}

	expectedTotalSize := int64(numLogs * 500) // 理论最小总字节数
	expectedMinSize := expectedTotalSize / 10 // 接受最多 90% 丢失
	actualSize := info.Size()

	t.Logf("Memory/disk usage test:")
	t.Logf("  Logs written: %d", numLogs)
	t.Logf("  Message size: 500 bytes")
	t.Logf("  File size: %.2f MB", float64(actualSize)/1024/1024)
	t.Logf("  Duration: %v", elapsed)
	t.Logf("  Write speed: %.2f MB/s", float64(actualSize)/1024/1024/elapsed.Seconds())
	t.Logf("  Persistence ratio: %.1f%%", float64(actualSize)/float64(expectedTotalSize)*100)

	if actualSize < expectedMinSize {
		t.Errorf("file size too small: got %d bytes, expected at least %d", actualSize, expectedMinSize)
	}
}

// TestLoggerFlushTimeout 测试 Flush 超时机制
func TestLoggerFlushTimeout(t *testing.T) {
	logger, err := NewLoggerWithSuffix("flush")
	if err != nil {
		t.Fatal(err)
	}
	defer logger.Close()

	// 写入一些日志
	for i := 0; i < 100; i++ {
		logger.Info(fmt.Sprintf("test-log-%d", i))
	}

	// 测试 Flush 应该在合理时间内完成
	start := time.Now()
	logger.Flush()
	duration := time.Since(start)

	t.Logf("Flush duration: %v", duration)

	if duration > 6*time.Second {
		t.Errorf("Flush took too long: %v (expected < 6s)", duration)
	}
}

// TestLoggerOrderPreservation 测试日志顺序保持
func TestLoggerOrderPreservation(t *testing.T) {
	logger, err := NewLoggerWithSuffix("order")
	if err != nil {
		t.Fatal(err)
	}
	defer logger.Close()

	const numGoroutines = 10
	const logsPerRoutine = 100

	var wg sync.WaitGroup
	for i := 0; i < numGoroutines; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()
			for j := 0; j < logsPerRoutine; j++ {
				logger.Info(fmt.Sprintf("G%d-SEQ%04d", id, j))
			}
		}(i)
	}

	wg.Wait()
	logger.Flush()

	// 读取并验证每个 goroutine 的日志顺序
	data, err := os.ReadFile(logger.Path())
	if err != nil {
		t.Fatal(err)
	}

	scanner := bufio.NewScanner(strings.NewReader(string(data)))
	sequences := make(map[int][]int) // goroutine ID -> sequence numbers

	for scanner.Scan() {
		line := scanner.Text()
		var gid, seq int
		parts := strings.SplitN(line, " INFO: ", 2)
		if len(parts) != 2 {
			t.Errorf("invalid log format: %s", line)
			continue
		}
		if _, err := fmt.Sscanf(parts[1], "G%d-SEQ%d", &gid, &seq); err == nil {
			sequences[gid] = append(sequences[gid], seq)
		} else {
			t.Errorf("failed to parse sequence from line: %s", line)
		}
	}

	// 验证每个 goroutine 内部顺序
	for gid, seqs := range sequences {
		for i := 0; i < len(seqs)-1; i++ {
			if seqs[i] >= seqs[i+1] {
				t.Errorf("Goroutine %d: out of order at index %d: %d >= %d",
					gid, i, seqs[i], seqs[i+1])
			}
		}
		if len(seqs) != logsPerRoutine {
			t.Errorf("Goroutine %d: missing logs, got %d, want %d",
				gid, len(seqs), logsPerRoutine)
		}
	}

	t.Logf("Order preservation test: all %d goroutines maintained sequence order", len(sequences))
}