using Microsoft.Extensions.Logging;

namespace DiscordArchiveManager.Services;

public class ArchiveService
{
    private readonly ILogger<ArchiveService> _logger;

    public ArchiveService(ILogger<ArchiveService> logger)
    {
        _logger = logger;
    }

    /// <summary>
    /// Archives a JSON file and its associated _Files directory to the archive location.
    /// </summary>
    /// <param name="jsonFilePath">Path to the JSON file</param>
    /// <param name="archiveRoot">Root directory for archives</param>
    /// <returns>Path to the archived JSON file</returns>
    public string ArchiveExport(string jsonFilePath, string archiveRoot)
    {
        if (!File.Exists(jsonFilePath))
        {
            throw new FileNotFoundException($"JSON file not found: {jsonFilePath}");
        }

        var jsonFileName = Path.GetFileName(jsonFilePath);
        var jsonDirectory = Path.GetDirectoryName(jsonFilePath)!;
        var filesDirectory = GetFilesDirectoryPath(jsonFilePath);

        // Create archive subdirectory based on date
        var archiveSubdir = DateTime.Now.ToString("yyyy-MM-dd");
        var archivePath = Path.Combine(archiveRoot, archiveSubdir);
        Directory.CreateDirectory(archivePath);

        // Archive the JSON file
        var archivedJsonPath = Path.Combine(archivePath, jsonFileName);
        var uniqueJsonPath = GetUniquePath(archivedJsonPath);
        MoveFile(jsonFilePath, uniqueJsonPath);
        _logger.LogInformation("Archived JSON file to {Path}", uniqueJsonPath);

        // Archive the _Files directory if it exists
        if (Directory.Exists(filesDirectory))
        {
            var filesDirectoryName = Path.GetFileName(filesDirectory);
            var archivedFilesPath = Path.Combine(archivePath, filesDirectoryName);
            var uniqueFilesPath = GetUniquePath(archivedFilesPath);
            MoveDirectory(filesDirectory, uniqueFilesPath);
            _logger.LogInformation("Archived files directory to {Path}", uniqueFilesPath);
        }

        return uniqueJsonPath;
    }

    /// <summary>
    /// Gets the path to the _Files directory associated with a JSON export file.
    /// DiscordChatExporter creates directories named like "filename.json_Files"
    /// </summary>
    public string GetFilesDirectoryPath(string jsonFilePath)
    {
        return jsonFilePath + "_Files";
    }

    /// <summary>
    /// Gets the path to a specific file within the _Files directory.
    /// </summary>
    public string? GetAttachmentFilePath(string jsonFilePath, string attachmentUrl)
    {
        var filesDirectory = GetFilesDirectoryPath(jsonFilePath);
        if (!Directory.Exists(filesDirectory))
        {
            return null;
        }

        // DiscordChatExporter stores files with their original filename
        // The URL format is usually like: https://cdn.discordapp.com/attachments/.../filename.ext
        string fileName;
        try
        {
            if (string.IsNullOrWhiteSpace(attachmentUrl))
            {
                return null;
            }
            fileName = Path.GetFileName(new Uri(attachmentUrl).LocalPath);
        }
        catch (UriFormatException)
        {
            // If URL is malformed, try to extract filename directly
            fileName = Path.GetFileName(attachmentUrl);
            if (string.IsNullOrWhiteSpace(fileName))
            {
                return null;
            }
        }
        var filePath = Path.Combine(filesDirectory, fileName);

        // Also check for URL-encoded versions
        var decodedFileName = Uri.UnescapeDataString(fileName);
        var decodedFilePath = Path.Combine(filesDirectory, decodedFileName);

        if (File.Exists(filePath))
        {
            return filePath;
        }
        if (File.Exists(decodedFilePath))
        {
            return decodedFilePath;
        }

        // Search for the file by partial match (in case of naming differences)
        var searchPattern = "*" + Path.GetExtension(fileName);
        var files = Directory.GetFiles(filesDirectory, searchPattern);

        // Try to find a file that contains the attachment ID from the URL
        var urlParts = attachmentUrl.Split('/');
        foreach (var file in files)
        {
            var currentFileName = Path.GetFileName(file);
            if (currentFileName.Equals(fileName, StringComparison.OrdinalIgnoreCase) ||
                currentFileName.Equals(decodedFileName, StringComparison.OrdinalIgnoreCase))
            {
                return file;
            }
        }

        return null;
    }

    /// <summary>
    /// Lists all JSON export files in the input directory.
    /// </summary>
    public IEnumerable<string> GetExportFiles(string inputDirectory)
    {
        if (!Directory.Exists(inputDirectory))
        {
            _logger.LogWarning("Input directory does not exist: {Path}", inputDirectory);
            yield break;
        }

        foreach (var file in Directory.EnumerateFiles(inputDirectory, "*.json", SearchOption.AllDirectories))
        {
            // Skip files in hidden directories (starting with .)
            var relativePath = Path.GetRelativePath(inputDirectory, file);
            if (relativePath.Split(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar)
                .Any(part => part.StartsWith('.')))
            {
                _logger.LogDebug("Skipping file in hidden directory: {Path}", file);
                continue;
            }

            yield return file;
        }
    }

    /// <summary>
    /// Moves a file, falling back to copy+delete for cross-device moves.
    /// </summary>
    private static void MoveFile(string source, string destination)
    {
        try
        {
            File.Move(source, destination);
        }
        catch (IOException)
        {
            File.Copy(source, destination);
            File.Delete(source);
        }
    }

    /// <summary>
    /// Moves a directory, falling back to copy+delete for cross-device moves.
    /// </summary>
    private static void MoveDirectory(string source, string destination)
    {
        try
        {
            Directory.Move(source, destination);
        }
        catch (IOException)
        {
            CopyDirectory(source, destination);
            Directory.Delete(source, true);
        }
    }

    /// <summary>
    /// Recursively copies a directory.
    /// </summary>
    private static void CopyDirectory(string source, string destination)
    {
        Directory.CreateDirectory(destination);

        foreach (var file in Directory.GetFiles(source))
        {
            var destFile = Path.Combine(destination, Path.GetFileName(file));
            File.Copy(file, destFile);
        }

        foreach (var dir in Directory.GetDirectories(source))
        {
            var destDir = Path.Combine(destination, Path.GetFileName(dir));
            CopyDirectory(dir, destDir);
        }
    }

    /// <summary>
    /// Gets a unique file/directory path by appending a number if the path already exists.
    /// </summary>
    private static string GetUniquePath(string path)
    {
        if (!File.Exists(path) && !Directory.Exists(path))
        {
            return path;
        }

        var directory = Path.GetDirectoryName(path)!;
        var fileName = Path.GetFileNameWithoutExtension(path);
        var extension = Path.GetExtension(path);

        var counter = 1;
        string newPath;
        do
        {
            newPath = Path.Combine(directory, $"{fileName}_{counter}{extension}");
            counter++;
        } while (File.Exists(newPath) || Directory.Exists(newPath));

        return newPath;
    }
}