using System.IO.Abstractions;

namespace qdr.app.studiou.orders2printpack.EmailStorage
{
    /// <summary>
    /// Helper class for working with email items and their file operations.
    /// Provides a convenient wrapper around MetadataItem with additional functionality
    /// for file system operations, validation, and state management.
    /// </summary>
    public class EmailItem
    {
        #region Private Fields
        
        /// <summary>
        /// The underlying metadata item containing email and processing information
        /// </summary>
        private readonly MetadataItem _metadata;
        
        /// <summary>
        /// Base directory path where email item directories are located
        /// </summary>
        private readonly string _basePath;

        /// <summary>
        /// File system abstraction for testable file operations
        /// </summary>
        private readonly IFileSystem _fileSystem;

        #endregion

        #region Constructor

        /// <summary>
        /// Initializes a new instance of the EmailItem class
        /// </summary>
        /// <param name="metadata">The metadata item containing email information</param>
        /// <param name="basePath">Base directory path for file operations</param>
        /// <param name="fileSystem">File system abstraction for file operations</param>
        /// <exception cref="ArgumentNullException">Thrown when metadata, basePath, or fileSystem is null</exception>
        public EmailItem(MetadataItem metadata, string basePath, IFileSystem fileSystem)
        {
            _metadata = metadata ?? throw new ArgumentNullException(nameof(metadata));
            _basePath = basePath ?? throw new ArgumentNullException(nameof(basePath));
            _fileSystem = fileSystem ?? throw new ArgumentNullException(nameof(fileSystem));
        }

        #endregion

        #region Public Properties

        /// <summary>
        /// Gets the underlying metadata item
        /// </summary>
        public MetadataItem Metadata => _metadata;
        
        /// <summary>
        /// Gets the full directory path for this email item
        /// Combines the base path with the directory name from metadata
        /// </summary>
        public string DirectoryPath => _fileSystem.Path.Combine(_basePath, _metadata.DirectoryName);
        
        /// <summary>
        /// Gets a value indicating whether the directory exists on the file system
        /// </summary>
        public bool DirectoryExists => _fileSystem.Directory.Exists(DirectoryPath);
        
        /// <summary>
        /// Gets all JPG files in the email item's directory
        /// Returns an empty enumerable if the directory doesn't exist
        /// </summary>
        public IEnumerable<string> JpgFiles => 
            DirectoryExists ? _fileSystem.Directory.GetFiles(DirectoryPath, "*.jpg") : Enumerable.Empty<string>();
        
        /// <summary>
        /// Gets the count of JPG files in the directory
        /// </summary>
        public int FileCount => JpgFiles.Count();
        
        /// <summary>
        /// Gets the total size in bytes of all JPG files in the directory
        /// </summary>
        public long TotalFileSize => JpgFiles.Sum(f => _fileSystem.FileInfo.New(f).Length);
        
        /// <summary>
        /// Gets a value indicating whether this item is ready for processing
        /// Checks that the state is Ready, directory exists, and contains files
        /// </summary>
        public bool IsReadyForProcessing => 
            _metadata.State == EmailStateEnum.Ready && DirectoryExists && FileCount > 0;
        
        /// <summary>
        /// Gets a value indicating whether this item can be reset
        /// Items cannot be reset while they are being processed or uploaded
        /// </summary>
        public bool CanBeReset => 
            _metadata.State != EmailStateEnum.Processing && 
            _metadata.State != EmailStateEnum.Uploading;

        /// <summary>
        /// Gets the normalized filename for the recipient (safe for file system)
        /// Replaces @ with _at_ and . with _dot_ to create filesystem-safe names
        /// </summary>
        public string NormalizedRecipient => 
            _metadata.EmailAddress.Replace("@", "_at_").Replace(".", "_dot_");

        #endregion

        #region Public Methods

        /// <summary>
        /// Generates the zip filename for this item based on recipient and timestamp
        /// </summary>
        /// <param name="timestamp">Optional timestamp to use, defaults to current time</param>
        /// <returns>A formatted zip filename in the format: studioufoto_{recipient}_{timestamp}.zip</returns>
        public string GenerateZipFileName(DateTime? timestamp = null) =>
            $"studioufoto_{NormalizedRecipient}_{(timestamp ?? DateTime.Now):yyyyMMdd_HHmmss}.zip";

        /// <summary>
        /// Validates that the item is in a consistent state for processing
        /// </summary>
        /// <returns>A tuple containing validation result and list of issues found</returns>
        public (bool IsValid, List<string> Issues) Validate()
        {
            var issues = new List<string>();

            // Check required email address
            if (string.IsNullOrEmpty(_metadata.EmailAddress))
                issues.Add("Email address is required");

            // Check directory and files existence
            if (!DirectoryExists)
                issues.Add($"Directory does not exist: {DirectoryPath}");
            else if (FileCount == 0)
                issues.Add("No JPG files found in directory");

            // Check required email content
            if (string.IsNullOrEmpty(_metadata.Subject))
                issues.Add("Email subject is required");

            if (string.IsNullOrEmpty(_metadata.Body))
                issues.Add("Email body is required");

            return (issues.Count == 0, issues);
        }

        /// <summary>
        /// Gets a summary of the item for display purposes
        /// Includes recipient, file count, current state, and associated orders
        /// </summary>
        /// <returns>A formatted summary string</returns>
        public string GetSummary() =>
            $"{_metadata.EmailAddress} - {FileCount} files, {_metadata.State}, Orders: {_metadata.Orders}";

        /// <summary>
        /// Gets detailed file information for all JPG files in the directory
        /// </summary>
        /// <returns>Collection of file information objects</returns>
        public IEnumerable<IFileInfo> GetFileDetails() =>
            JpgFiles.Select(f => _fileSystem.FileInfo.New(f));

        /// <summary>
        /// Checks if a specific file exists in the email item's directory
        /// </summary>
        /// <param name="fileName">Name of the file to check</param>
        /// <returns>True if the file exists, false otherwise</returns>
        public bool FileExists(string fileName)
        {
            if (string.IsNullOrEmpty(fileName))
                return false;

            var filePath = _fileSystem.Path.Combine(DirectoryPath, fileName);
            return _fileSystem.File.Exists(filePath);
        }

        /// <summary>
        /// Gets the full path for a file within the email item's directory
        /// </summary>
        /// <param name="fileName">Name of the file</param>
        /// <returns>Full path to the file</returns>
        public string GetFilePath(string fileName) =>
            _fileSystem.Path.Combine(DirectoryPath, fileName);

        /// <summary>
        /// Creates the email item's directory if it doesn't exist
        /// </summary>
        /// <returns>True if directory was created or already exists, false if creation failed</returns>
        public bool EnsureDirectoryExists()
        {
            try
            {
                if (!DirectoryExists)
                {
                    _fileSystem.Directory.CreateDirectory(DirectoryPath);
                }
                return true;
            }
            catch
            {
                return false;
            }
        }

        /// <summary>
        /// Gets file information for a specific file in the directory
        /// </summary>
        /// <param name="fileName">Name of the file</param>
        /// <returns>File information object, or null if file doesn't exist</returns>
        public IFileInfo? GetFileInfo(string fileName)
        {
            if (string.IsNullOrEmpty(fileName))
                return null;

            var filePath = GetFilePath(fileName);
            return _fileSystem.File.Exists(filePath) ? _fileSystem.FileInfo.New(filePath) : null;
        }

        #endregion
    }
}