using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using HtmlToPdfService.Core.Options;

namespace HtmlToPdfService.Core.Storage;

/// <summary>
/// 本地文件存储实现
/// </summary>
public class LocalFileStorage : IFileStorage
{
    private readonly StorageOptions _options;
    private readonly ILogger<LocalFileStorage> _logger;

    public LocalFileStorage(IOptions<PdfServiceOptions> options, ILogger<LocalFileStorage> logger)
    {
        _options = options.Value.Storage;
        _logger = logger;

        // 确保存储目录存在
        if (!Directory.Exists(_options.LocalPath))
        {
            Directory.CreateDirectory(_options.LocalPath);
            _logger.LogInformation("创建存储目录: {Path}", _options.LocalPath);
        }
    }

    /// <summary>
    /// 保存 PDF 文件
    /// </summary>
    public async Task<(string FilePath, string DownloadUrl)> SaveAsync(
        string requestId,
        byte[] pdfData,
        CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrEmpty(requestId))
            throw new ArgumentException("请求 ID 不能为空", nameof(requestId));

        if (pdfData == null || pdfData.Length == 0)
            throw new ArgumentException("PDF 数据不能为空", nameof(pdfData));

        try
        {
            // 按日期组织目录结构：/pdfs/yyyy-MM-dd/
            var dateFolder = DateTime.UtcNow.ToString("yyyy-MM-dd");
            var dailyPath = Path.Combine(_options.LocalPath, dateFolder);

            if (!Directory.Exists(dailyPath))
            {
                Directory.CreateDirectory(dailyPath);
            }

            var fileName = $"{requestId}.pdf";
            var filePath = Path.Combine(dailyPath, fileName);

            // 保存文件
            await File.WriteAllBytesAsync(filePath, pdfData, cancellationToken);

            _logger.LogInformation("PDF 文件已保存: {FilePath}, 大小: {Size} bytes", 
                filePath, pdfData.Length);

            // 构造下载 URL（相对路径）
            var downloadUrl = $"/api/pdf/download/{requestId}";

            return (filePath, downloadUrl);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "保存 PDF 文件失败: {RequestId}", requestId);
            throw;
        }
    }

    /// <summary>
    /// 获取文件
    /// </summary>
    public async Task<byte[]?> GetAsync(string requestId, CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrEmpty(requestId))
            throw new ArgumentException("请求 ID 不能为空", nameof(requestId));

        try
        {
            // 搜索最近几天的目录
            var searchDays = Math.Max(1, _options.RetentionHours / 24 + 1);
            for (int i = 0; i < searchDays; i++)
            {
                var date = DateTime.UtcNow.AddDays(-i).ToString("yyyy-MM-dd");
                var filePath = Path.Combine(_options.LocalPath, date, $"{requestId}.pdf");

                if (File.Exists(filePath))
                {
                    _logger.LogDebug("找到 PDF 文件: {FilePath}", filePath);
                    return await File.ReadAllBytesAsync(filePath, cancellationToken);
                }
            }

            _logger.LogWarning("未找到 PDF 文件: {RequestId}", requestId);
            return null;
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "读取 PDF 文件失败: {RequestId}", requestId);
            throw;
        }
    }

    /// <summary>
    /// 删除文件
    /// </summary>
    public Task DeleteAsync(string requestId, CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrEmpty(requestId))
            throw new ArgumentException("请求 ID 不能为空", nameof(requestId));

        try
        {
            // 搜索并删除文件
            var searchDays = Math.Max(1, _options.RetentionHours / 24 + 1);
            for (int i = 0; i < searchDays; i++)
            {
                var date = DateTime.UtcNow.AddDays(-i).ToString("yyyy-MM-dd");
                var filePath = Path.Combine(_options.LocalPath, date, $"{requestId}.pdf");

                if (File.Exists(filePath))
                {
                    File.Delete(filePath);
                    _logger.LogInformation("已删除 PDF 文件: {FilePath}", filePath);
                    break;
                }
            }
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "删除 PDF 文件失败: {RequestId}", requestId);
            throw;
        }

        return Task.CompletedTask;
    }

    /// <summary>
    /// 清理过期文件
    /// </summary>
    public Task CleanupExpiredFilesAsync(CancellationToken cancellationToken = default)
    {
        try
        {
            if (!Directory.Exists(_options.LocalPath))
                return Task.CompletedTask;

            var expirationTime = DateTime.UtcNow.AddHours(-_options.RetentionHours);
            var deletedCount = 0;

            // 遍历所有日期目录
            var directories = Directory.GetDirectories(_options.LocalPath);
            foreach (var directory in directories)
            {
                if (cancellationToken.IsCancellationRequested)
                    break;

                try
                {
                    // 检查目录中的文件
                    var files = Directory.GetFiles(directory, "*.pdf");
                    foreach (var file in files)
                    {
                        var fileInfo = new FileInfo(file);
                        if (fileInfo.LastWriteTimeUtc < expirationTime)
                        {
                            File.Delete(file);
                            deletedCount++;
                        }
                    }

                    // 如果目录为空，删除目录
                    if (!Directory.EnumerateFileSystemEntries(directory).Any())
                    {
                        Directory.Delete(directory);
                    }
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, "清理目录失败: {Directory}", directory);
                }
            }

            if (deletedCount > 0)
            {
                _logger.LogInformation("清理过期文件完成，删除了 {Count} 个文件", deletedCount);
            }
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "清理过期文件失败");
        }

        return Task.CompletedTask;
    }
}