using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace FATrace.OEMApp.Utils
{
    public static class LogReader
    {
        public static IEnumerable<string> ReadTailLines(string filePath, int lineCount)
        {
            if (string.IsNullOrWhiteSpace(filePath) || !File.Exists(filePath))
                return Enumerable.Empty<string>();

            var lines = new LinkedList<string>();
            try
            {
                using var fs = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
                using var sr = new StreamReader(fs);
                string? line;
                while ((line = sr.ReadLine()) != null)
                {
                    lines.AddLast(line);
                    if (lines.Count > lineCount) lines.RemoveFirst();
                }
            }
            catch
            {
                return Enumerable.Empty<string>();
            }
            return lines;
        }

        public static string GetTodayLogPath()
        {
            var baseDir = AppContext.BaseDirectory;
            var logDir = Path.Combine(baseDir, "logs");
            var file = Path.Combine(logDir, DateTime.Now.ToString("yyyy-MM-dd") + ".log");
            return file;
        }
    }
}