using System;
using System.Globalization;
using System.IO;
using HC_APTBS.Services;

namespace HC_APTBS.Infrastructure.Logging
{
    /// <summary>
    /// File-based application logger.
    /// Log files are written to <c>%UserProfile%\.HC_APTBS\log\</c> with
    /// daily rotation using the filename pattern <c>LOG_yyyy_MM_dd.txt</c>.
    /// Entries are appended with a timestamp prefix and a severity tag.
    /// </summary>
    public sealed class AppLogger : IAppLogger
    {
        // ── Constants ────────────────────────────────────────────────────────────

        private const string TagError   = "ERR";
        private const string TagWarning = "WAR";
        private const string TagMessage = "MSG";
        private const string TagDebug   = "DBG";

        private static readonly string LogFolder =
            Path.Combine(
                Environment.GetFolderPath(Environment.SpecialFolder.UserProfile),
                ".HC_APTBS", "log");

        // ── IAppLogger ────────────────────────────────────────────────────────────

        /// <inheritdoc/>
        public void Error(string source, string message)   => Write(source, message, TagError);

        /// <inheritdoc/>
        public void Warning(string source, string message) => Write(source, message, TagWarning);

        /// <inheritdoc/>
        public void Info(string source, string message)    => Write(source, message, TagMessage);

        /// <inheritdoc/>
        public void Debug(string source, string message)   => Write(source, message, TagDebug);

        // ── Helpers ───────────────────────────────────────────────────────────────

        private static void Write(string source, string message, string tag)
        {
            try
            {
                Directory.CreateDirectory(LogFolder);
                string path = Path.Combine(LogFolder,
                    $"LOG_{DateTime.Now:yyyy_MM_dd}.txt");

                string line = $"{Timestamp()}[{tag}] {source.ToUpperInvariant()}-> {message}{Environment.NewLine}";
                File.AppendAllText(path, line);
            }
            catch
            {
                // If logging fails (disk full, permissions) we swallow the error
                // rather than crashing the application.
                Console.WriteLine($"[{tag}] {source}: {message}");
            }
        }

        /// <summary>Returns the current time formatted as <c>[HH:mm:ss] </c>.</summary>
        private static string Timestamp()
            => DateTime.Now.ToString("[HH:mm:ss] ", DateTimeFormatInfo.InvariantInfo);

        /// <summary>
        /// Writes the application start banner to today's log file.
        /// Call once from <c>App.OnStartup</c>.
        /// </summary>
        public void WriteStartupBanner(string version)
        {
            string sep = "******************************************";
            string banner =
                sep + Environment.NewLine +
                sep + Environment.NewLine +
                $"** STARTED {version} {DateTime.Now:dd/MM/yyyy HH:mm:ss} **" + Environment.NewLine +
                sep + Environment.NewLine +
                sep + Environment.NewLine;

            try
            {
                Directory.CreateDirectory(LogFolder);
                File.AppendAllText(
                    Path.Combine(LogFolder, $"LOG_{DateTime.Now:yyyy_MM_dd}.txt"),
                    banner);
            }
            catch { /* swallow */ }
        }

        /// <summary>
        /// Writes the application shutdown footer to today's log file.
        /// Call once from <c>App.OnExit</c>.
        /// </summary>
        public void WriteShutdownFooter()
        {
            string footer =
                "-----------------------------------------------" + Environment.NewLine +
                $"-- STOPPED {DateTime.Now:dd/MM/yyyy HH:mm:ss} --" + Environment.NewLine +
                "-----------------------------------------------" + Environment.NewLine +
                Environment.NewLine;

            try
            {
                File.AppendAllText(
                    Path.Combine(LogFolder, $"LOG_{DateTime.Now:yyyy_MM_dd}.txt"),
                    footer);
            }
            catch { /* swallow */ }
        }
    }
}