package applog

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

func TestDailyFileWriterRotatesAndCleans(t *testing.T) {
	dir := t.TempDir()
	logFile := filepath.Join(dir, "app.log")

	w, err := newDailyFileWriter(logFile)
	if err != nil {
		t.Fatalf("new writer: %v", err)
	}
	defer w.Close()

	// 写入当天日志，文件应按 app-YYYYMMDD.log 命名
	today := time.Now().Format("20060102")
	if _, err := w.Write([]byte("line1\n")); err != nil {
		t.Fatalf("write: %v", err)
	}
	todayPath := filepath.Join(dir, "app-"+today+".log")
	if _, err := os.Stat(todayPath); err != nil {
		t.Fatalf("today log file missing: %v", err)
	}
	// 旧格式 app.log 不应被创建
	if _, err := os.Stat(logFile); err == nil {
		t.Fatalf("old-style app.log should not be created")
	}

	// 构造过期文件，cleanup 应删除（保留 30 天，这里用 3 天验证）
	old := filepath.Join(dir, "app-20260701.log")
	if err := os.WriteFile(old, []byte("old"), 0o644); err != nil {
		t.Fatalf("create old file: %v", err)
	}
	w.cleanup(time.Now())
	if _, err := os.Stat(old); err == nil {
		t.Fatalf("old log file should be cleaned")
	}
	// 当天的文件应保留
	if _, err := os.Stat(todayPath); err != nil {
		t.Fatalf("today log file should be kept")
	}
}