using System.IO;
using AxiOmron.PcbCheck.Models;
using AxiOmron.PcbCheck.Options;
using AxiOmron.PcbCheck.Services.Interfaces;

namespace AxiOmron.PcbCheck.Services.Implementations;

/// <summary>
/// 提供本地磁盘目录的文件存在性校验能力。
/// </summary>
public sealed class LocalFileCheckProvider : IFileCheckProvider
{
    private readonly IAppLogger<LocalFileCheckProvider> _logger;

    /// <summary>
    /// 初始化本地文件校验提供程序。
    /// </summary>
    /// <param name="logger">日志记录器。</param>
    public LocalFileCheckProvider(IAppLogger<LocalFileCheckProvider> logger)
    {
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
    }

    /// <summary>
    /// 获取当前提供程序对应的通道类型。
    /// </summary>
    public FileCheckProvider Provider => FileCheckProvider.Local;

    /// <summary>
    /// 按条码检查本地目录中是否存在目标文件。
    /// </summary>
    /// <param name="barcode">条码内容。</param>
    /// <param name="config">根配置对象。</param>
    /// <param name="cancellationToken">取消令牌。取消后立即终止目录枚举。</param>
    /// <returns>文件校验结果。</returns>
    public async Task<FileCheckOutcome> CheckFileAsync(string barcode, AppConfig config, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(config);
        if (string.IsNullOrWhiteSpace(barcode))
        {
            return new FileCheckOutcome
            {
                Exists = false,
                IsConfigurationError = true,
                ErrorMessage = "条码为空，无法执行本地文件查询。"
            };
        }

        FileCheckTestOutcome testOutcome = ValidateRootPath(config.FileCheck.Local.RootPath);
        if (!testOutcome.IsSuccess)
        {
            return new FileCheckOutcome
            {
                Exists = false,
                IsConfigurationError = testOutcome.IsConfigurationError,
                IsSystemError = testOutcome.IsSystemError,
                ErrorMessage = testOutcome.StatusMessage
            };
        }

        return await Task.Run(() => CheckInternal(barcode, config, cancellationToken), cancellationToken).ConfigureAwait(false);
    }

    /// <summary>
    /// 删除本地文件校验返回的精确命中文件。
    /// 删除前会校验目标必须位于配置的本地根目录内，文件已不存在时按幂等成功处理。
    /// </summary>
    /// <param name="filePath">文件校验返回的精确命中文件路径。</param>
    /// <param name="config">根配置对象。</param>
    /// <param name="cancellationToken">取消令牌。取消后终止尚未完成的删除操作。</param>
    /// <returns>文件删除结果。</returns>
    public async Task<FileDeleteOutcome> DeleteFileAsync(string filePath, AppConfig config, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(config);
        if (string.IsNullOrWhiteSpace(filePath))
        {
            return new FileDeleteOutcome
            {
                IsSuccess = false,
                FilePath = filePath,
                ErrorMessage = "待删除的本地产品 ID 文件路径为空。"
            };
        }

        return await Task.Run(
                () => DeleteInternal(filePath, config.FileCheck.Local.RootPath, cancellationToken),
                cancellationToken)
            .ConfigureAwait(false);
    }

    /// <summary>
    /// 测试本地文件校验目录是否可访问。
    /// </summary>
    /// <param name="config">根配置对象。</param>
    /// <param name="cancellationToken">取消令牌。取消后立即终止测试。</param>
    /// <returns>通道测试结果。</returns>
    public Task<FileCheckTestOutcome> TestConnectionAsync(AppConfig config, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(config);
        cancellationToken.ThrowIfCancellationRequested();
        return Task.FromResult(ValidateRootPath(config.FileCheck.Local.RootPath));
    }

    /// <summary>
    /// 在同步上下文中执行本地文件查找。
    /// </summary>
    /// <param name="barcode">条码内容。</param>
    /// <param name="config">根配置对象。</param>
    /// <param name="cancellationToken">取消令牌。</param>
    /// <returns>文件校验结果。</returns>
    private FileCheckOutcome CheckInternal(string barcode, AppConfig config, CancellationToken cancellationToken)
    {
        cancellationToken.ThrowIfCancellationRequested();

        try
        {
            string rootPath = Path.GetFullPath(config.FileCheck.Local.RootPath);
            string candidateName = FileCheckPathMatcher.BuildExpectedFileName(barcode, config.FileCheck.FileNamePattern);
            string? matchedPath = Directory.EnumerateFiles(rootPath)
                .FirstOrDefault(path =>
                {
                    cancellationToken.ThrowIfCancellationRequested();
                    return FileCheckPathMatcher.IsMatch(Path.GetFileName(path), candidateName, barcode);
                });

            if (matchedPath is null)
            {
                return new FileCheckOutcome
                {
                    Exists = false,
                    ConnectionSucceeded = true,
                    ErrorMessage = $"未找到与条码 {barcode} 匹配的本地文件。"
                };
            }

            return new FileCheckOutcome
            {
                Exists = true,
                ConnectionSucceeded = true,
                MatchedFilePath = matchedPath
            };
        }
        catch (OperationCanceledException)
        {
            throw;
        }
        catch (Exception ex) when (ex is IOException or UnauthorizedAccessException or System.Security.SecurityException)
        {
            _logger.LogError(ex, "本地文件校验异常");
            return new FileCheckOutcome
            {
                Exists = false,
                IsSystemError = true,
                ErrorMessage = $"本地文件校验异常: {ex.Message}"
            };
        }
    }

    /// <summary>
    /// 在同步上下文中安全删除本地产品 ID 文件。
    /// </summary>
    /// <param name="filePath">待删除文件路径。</param>
    /// <param name="rootPath">配置的本地根目录。</param>
    /// <param name="cancellationToken">取消令牌。</param>
    /// <returns>文件删除结果。</returns>
    private FileDeleteOutcome DeleteInternal(string filePath, string rootPath, CancellationToken cancellationToken)
    {
        cancellationToken.ThrowIfCancellationRequested();

        try
        {
            string fullRootPath = Path.GetFullPath(rootPath);
            string fullFilePath = Path.GetFullPath(filePath);
            if (!IsPathWithinRoot(fullFilePath, fullRootPath))
            {
                return new FileDeleteOutcome
                {
                    IsSuccess = false,
                    FilePath = fullFilePath,
                    ErrorMessage = $"拒绝删除本地根目录之外的文件: {fullFilePath}"
                };
            }

            if (!File.Exists(fullFilePath))
            {
                return new FileDeleteOutcome
                {
                    IsSuccess = true,
                    WasAlreadyMissing = true,
                    FilePath = fullFilePath
                };
            }

            File.Delete(fullFilePath);
            return new FileDeleteOutcome
            {
                IsSuccess = true,
                FilePath = fullFilePath
            };
        }
        catch (OperationCanceledException)
        {
            throw;
        }
        catch (Exception ex) when (ex is IOException
                                   or UnauthorizedAccessException
                                   or System.Security.SecurityException
                                   or ArgumentException
                                   or NotSupportedException)
        {
            _logger.LogError(ex, "删除本地产品 ID 文件异常，路径={FilePath}", true, filePath);
            return new FileDeleteOutcome
            {
                IsSuccess = false,
                FilePath = filePath,
                ErrorMessage = $"删除本地产品 ID 文件失败: {ex.Message}"
            };
        }
    }

    /// <summary>
    /// 判断目标文件是否位于配置根目录内，防止外部路径被误删。
    /// </summary>
    /// <param name="fullFilePath">目标文件绝对路径。</param>
    /// <param name="fullRootPath">配置根目录绝对路径。</param>
    /// <returns>目标位于根目录内返回 <see langword="true"/>；否则返回 <see langword="false"/>。</returns>
    private static bool IsPathWithinRoot(string fullFilePath, string fullRootPath)
    {
        string relativePath = Path.GetRelativePath(fullRootPath, fullFilePath);
        return !Path.IsPathRooted(relativePath)
               && !string.Equals(relativePath, "..", StringComparison.Ordinal)
               && !relativePath.StartsWith($"..{Path.DirectorySeparatorChar}", StringComparison.Ordinal)
               && !relativePath.StartsWith($"..{Path.AltDirectorySeparatorChar}", StringComparison.Ordinal);
    }

    /// <summary>
    /// 验证本地根目录配置和可访问性。
    /// </summary>
    /// <param name="rootPath">本地根目录。</param>
    /// <returns>通道测试结果。</returns>
    private static FileCheckTestOutcome ValidateRootPath(string rootPath)
    {
        if (string.IsNullOrWhiteSpace(rootPath))
        {
            return new FileCheckTestOutcome
            {
                IsConfigurationError = true,
                StatusMessage = "本地文件校验目录未配置。"
            };
        }

        string fullPath;
        try
        {
            fullPath = Path.GetFullPath(rootPath);
        }
        catch (Exception ex) when (ex is ArgumentException or NotSupportedException or PathTooLongException)
        {
            return new FileCheckTestOutcome
            {
                IsConfigurationError = true,
                StatusMessage = $"本地文件校验目录配置无效: {ex.Message}"
            };
        }

        if (!Directory.Exists(fullPath))
        {
            return new FileCheckTestOutcome
            {
                IsConfigurationError = true,
                StatusMessage = $"本地文件校验目录不存在: {fullPath}"
            };
        }

        return new FileCheckTestOutcome
        {
            IsSuccess = true,
            ConnectionSucceeded = true,
            RootPathAccessible = true,
            StatusMessage = $"本地文件校验目录可访问: {fullPath}"
        };
    }
}