package main

import (
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"
)

func TestDailyWriterRotatesBySize(t *testing.T) {
	dir := t.TempDir()
	w, err := newDailyWriter(dir, "service-test", 30, 64, 1024)
	if err != nil {
		t.Fatal(err)
	}
	defer w.Close()

	if _, err = w.Write([]byte(strings.Repeat("a", 48))); err != nil {
		t.Fatal(err)
	}
	if _, err = w.Write([]byte(strings.Repeat("b", 48))); err != nil {
		t.Fatal(err)
	}
	files, err := filepath.Glob(filepath.Join(dir, "service-test-*.log"))
	if err != nil {
		t.Fatal(err)
	}
	if len(files) != 2 {
		t.Fatalf("expected 2 log parts, got %d: %v", len(files), files)
	}
}

func TestDailyWriterEnforcesTotalSize(t *testing.T) {
	dir := t.TempDir()
	oldPath := filepath.Join(dir, "service-old-2020-01-01.log")
	if err := os.WriteFile(oldPath, []byte(strings.Repeat("x", 90)), 0o644); err != nil {
		t.Fatal(err)
	}
	oldTime := time.Now().AddDate(0, 0, -2)
	if err := os.Chtimes(oldPath, oldTime, oldTime); err != nil {
		t.Fatal(err)
	}

	w, err := newDailyWriter(dir, "service-test", 30, 64, 100)
	if err != nil {
		t.Fatal(err)
	}
	defer w.Close()
	if _, err = w.Write([]byte(strings.Repeat("a", 64))); err != nil {
		t.Fatal(err)
	}
	if _, err = w.Write([]byte(strings.Repeat("b", 64))); err != nil {
		t.Fatal(err)
	}
	if _, err = os.Stat(oldPath); !os.IsNotExist(err) {
		t.Fatalf("oldest log should be removed, stat error: %v", err)
	}

	entries, err := os.ReadDir(dir)
	if err != nil {
		t.Fatal(err)
	}
	var total int64
	for _, entry := range entries {
		info, infoErr := entry.Info()
		if infoErr != nil {
			t.Fatal(infoErr)
		}
		total += info.Size()
	}
	if total > 128 { // 当前打开分卷允许最多超出一个 64 字节分卷。
		t.Fatalf("log directory grew unexpectedly: %d bytes", total)
	}
}