using System;
using System.IO;
using System.Linq;

namespace Engine.Core.Debug;

public class RotatingFileLogger : ILogger
{
    public readonly FileLogger FileLogger = null!;
    public readonly string Directory = string.Empty;
    public readonly int RotateLength = 3;

    public RotatingFileLogger(string directory, string namePrefix, string nameSuffix = "", int rotateLength = 3)
    {
        RotateLength = rotateLength;

        string fileName = Path.Combine(directory, namePrefix);
        if (!string.IsNullOrWhiteSpace(nameSuffix))
            fileName += $"_{nameSuffix}";

        bool isRelativePath = Path.GetFullPath(fileName).CompareTo(fileName) != 0;

        if (isRelativePath)
            fileName = Path.GetFullPath(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, fileName));

        if (File.Exists($"{fileName}.log"))
            RenameExistingLogs(fileName, RotateLength);

        FileLogger = new(fileName);

        Directory = Path.GetDirectoryName(fileName) ?? throw new("Unexpected error on getting directory of logger path");
        RotateLastLogs(Directory, namePrefix, RotateLength);
    }

    private static void RenameExistingLogs(string filePath, int rotateLength)
    {
        for (int i = rotateLength - 1; i >= 0; i--)
        {
            string source = i == 0
                ? $"{filePath}.log"
                : $"{filePath}_{i}.log";

            string dest = $"{filePath}_{i + 1}.log";

            if (!File.Exists(source))
                continue;

            if (File.Exists(dest))
                File.Delete(dest);

            File.Move(source, dest);
        }
    }

    private static void RotateLastLogs(string directory, string prefix, int rotateLength)
    {
        IOrderedEnumerable<string> logs = System.IO.Directory.GetFiles(directory, $"{prefix}*.log")
            .OrderBy(File.GetCreationTime);

        foreach (string file in logs.Skip(rotateLength))
            try
            {
                ILogger.Shared.Log($"Removing log file located at \"{file}\" during rotation.");
                File.Delete(file);
            }
            catch (Exception e) { ILogger.Shared.LogException($"Failed to rotate log file at \"{file}\"", e); }
    }

    public ILogger.Level FilterLevel { get => FileLogger.FilterLevel; set => FileLogger.FilterLevel = value; }
    public void Log(string message, ILogger.Level level = ILogger.Level.Info, bool force = false) => FileLogger.Log(message, level, force);
}