using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using ADOFAIRenderer.Core.Data;
using ADOFAIRenderer.Data;

namespace ADOFAIRenderer.Util;

/// <summary>
/// Formats and sanitizes render output file names according to customizable template patterns.
/// </summary>
internal static class RenderFileNameUtil
{
    private static readonly Regex RichTextRegex = new(@"<[^>]+>", RegexOptions.Compiled);
    private static readonly Regex TokenRegex = new(@"\{([a-zA-Z0-9_]+)\}", RegexOptions.Compiled);

    private static readonly HashSet<string> ReservedWindowsNames = new(StringComparer.OrdinalIgnoreCase)
    {
        "CON", "PRN", "AUX", "NUL",
        "COM1", "COM2", "COM3", "COM4", "COM5", "COM6", "COM7", "COM8", "COM9",
        "LPT1", "LPT2", "LPT3", "LPT4", "LPT5", "LPT6", "LPT7", "LPT8", "LPT9"
    };

    /// <summary>
    /// Removes Unity rich text tags (such as &lt;color=...&gt;, &lt;b&gt;, etc.) from the given text.
    /// </summary>
    public static string StripRichText(string? input)
    {
        if (string.IsNullOrEmpty(input)) return string.Empty;
        return RichTextRegex.Replace(input, string.Empty);
    }

    /// <summary>
    /// Replaces invalid file name characters within a single token with an underscore.
    /// </summary>
    public static string SanitizeToken(string? token)
    {
        if (string.IsNullOrEmpty(token)) return string.Empty;

        var invalidChars = Path.GetInvalidFileNameChars();
        var sb = new StringBuilder(token.Length);
        foreach (var c in token)
        {
            sb.Append(invalidChars.Contains(c) ? '_' : c);
        }

        return sb.ToString().Trim(' ', '.');
    }

    /// <summary>
    /// Sanitizes the final formatted file name, ensuring no illegal characters or Windows reserved device names.
    /// </summary>
    public static string SanitizeFileName(string? fileName)
    {
        if (string.IsNullOrWhiteSpace(fileName)) return string.Empty;

        var invalidChars = Path.GetInvalidFileNameChars();
        var sb = new StringBuilder(fileName.Length);
        foreach (var c in fileName)
        {
            sb.Append(invalidChars.Contains(c) ? '_' : c);
        }

        var result = sb.ToString().Trim(' ', '.');
        if (ReservedWindowsNames.Contains(result))
        {
            result = "_" + result;
        }

        return result;
    }

    /// <summary>
    /// Formats a file name without extension by substituting template variables.
    /// Available tokens: {song}, {title}, {artist}, {author}, {level}, {preset},
    /// {date}, {time}, {year}, {month}, {day}, {hour}, {minute}, {second},
    /// {resolution}, {width}, {height}, {fps}.
    /// </summary>
    public static string FormatFileName(
        string? formatTemplate,
        DateTime startTime,
        RenderConfig config,
        string? presetName = null,
        string? levelPath = null)
    {
        var scn = scnGame.instance;
        string rawSong = "";
        string rawArtist = "";
        string rawAuthor = "";

        if (scn != null && scn.levelData != null)
        {
            rawSong = scn.levelData.song ?? "";
            rawArtist = scn.levelData.artist ?? "";
            rawAuthor = scn.levelData.author ?? "";
        }

        if (string.IsNullOrWhiteSpace(rawSong) && !string.IsNullOrWhiteSpace(levelPath))
        {
            var dir = Path.GetDirectoryName(levelPath);
            rawSong = !string.IsNullOrWhiteSpace(dir)
                ? Path.GetFileName(dir)
                : Path.GetFileNameWithoutExtension(levelPath);
        }

        var song = SanitizeToken(StripRichText(rawSong));
        var artist = SanitizeToken(StripRichText(rawArtist));
        var author = SanitizeToken(StripRichText(rawAuthor));
        var level = !string.IsNullOrWhiteSpace(levelPath)
            ? SanitizeToken(Path.GetFileNameWithoutExtension(levelPath))
            : song;
        var preset = SanitizeToken(presetName ?? "");

        var date = startTime.ToString("yyyy-MM-dd");
        var time = startTime.ToString("HH-mm-ss");
        var year = startTime.ToString("yyyy");
        var month = startTime.ToString("MM");
        var day = startTime.ToString("dd");
        var hour = startTime.ToString("HH");
        var minute = startTime.ToString("mm");
        var second = startTime.ToString("ss");

        var width = config.RenderWidth.ToString();
        var height = config.RenderHeight.ToString();
        var resolution = $"{config.RenderWidth}x{config.RenderHeight}";

        var effectiveFps = Math.Min(config.VideoFPS, config.RenderFPS);
        var fps = Math.Abs(effectiveFps % 1) < 0.001
            ? ((int)effectiveFps).ToString()
            : effectiveFps.ToString("0.##");

        var tokens = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
        {
            { "song", song },
            { "title", song },
            { "artist", artist },
            { "author", author },
            { "level", level },
            { "preset", preset },
            { "date", date },
            { "time", time },
            { "year", year },
            { "month", month },
            { "day", day },
            { "hour", hour },
            { "minute", minute },
            { "second", second },
            { "width", width },
            { "height", height },
            { "resolution", resolution },
            { "fps", fps }
        };

        var template = string.IsNullOrWhiteSpace(formatTemplate)
            ? GlobalSettings.DefaultFileNameFormat
            : formatTemplate;

        var replaced = TokenRegex.Replace(template, match =>
        {
            var key = match.Groups[1].Value;
            return tokens.TryGetValue(key, out var val) ? val : match.Value;
        });

        var sanitized = SanitizeFileName(replaced);
        return string.IsNullOrWhiteSpace(sanitized)
            ? startTime.ToString("yyyy-MM-dd HH-mm-ss")
            : sanitized;
    }

    /// <summary>
    /// Returns a collision-free output file path by appending (1), (2), etc. if a file with the given name already exists.
    /// </summary>
    public static string GetUniqueFilePath(string directory, string fileNameWithoutExt, string ext)
    {
        var normalizedExt = "." + ext.TrimStart('.').ToLowerInvariant();
        var fileName = $"{fileNameWithoutExt}{normalizedExt}";
        var fullPath = Path.Combine(directory, fileName);

        var counter = 1;
        while (File.Exists(fullPath))
        {
            fileName = $"{fileNameWithoutExt} ({counter}){normalizedExt}";
            fullPath = Path.Combine(directory, fileName);
            counter++;
        }

        return fullPath;
    }
}