using System;
using System.IO;

namespace Alipay.AopSdk.Core.Util
{
	/// <summary>
	///     文件元数据。
	///     可以使用以下几种构造方法：
	///     本地路径：new FileItem("C:/temp.jpg");
	///     本地文件：new FileItem(new FileInfo("C:/temp.jpg"));
	///     字节流：new FileItem("abc.jpg", bytes);
	/// </summary>
	public class FileItem
	{
		private byte[] content;
		private readonly FileInfo fileInfo;
		private string fileName;
		private string mimeType;

		/// <summary>
		///     基于本地文件的构造器。
		/// </summary>
		/// <param name="fileInfo">本地文件</param>
		public FileItem(FileInfo fileInfo)
		{
			if (fileInfo == null || !fileInfo.Exists)
				throw new ArgumentException("fileInfo is null or not exists!");
			this.fileInfo = fileInfo;
		}

		/// <summary>
		///     基于本地文件全路径的构造器。
		/// </summary>
		/// <param name="filePath">本地文件全路径</param>
		public FileItem(string filePath)
			: this(new FileInfo(filePath))
		{
		}

		/// <summary>
		///     基于文件名和字节流的构造器。
		/// </summary>
		/// <param name="fileName">文件名称（服务端持久化字节流到磁盘时的文件名）</param>
		/// <param name="content">文件字节流</param>
		public FileItem(string fileName, byte[] content)
		{
			if (string.IsNullOrEmpty(fileName)) throw new ArgumentNullException("fileName");
			if (content == null || content.Length == 0) throw new ArgumentNullException("content");

			this.fileName = fileName;
			this.content = content;
		}

		/// <summary>
		///     基于文件名、字节流和媒体类型的构造器。
		/// </summary>
		/// <param name="fileName">文件名（服务端持久化字节流到磁盘时的文件名）</param>
		/// <param name="content">文件字节流</param>
		/// <param name="mimeType">媒体类型</param>
		public FileItem(string fileName, byte[] content, string mimeType)
			: this(fileName, content)
		{
			if (string.IsNullOrEmpty(mimeType)) throw new ArgumentNullException("mimeType");
			this.mimeType = mimeType;
		}

		public string GetFileName()
		{
			if (fileName == null && fileInfo != null && fileInfo.Exists)
				fileName = fileInfo.FullName;
			return fileName;
		}

		public string GetMimeType()
		{
			if (mimeType == null)
				mimeType = AopUtils.GetMimeType(GetContent());
			return mimeType;
		}

		public byte[] GetContent()
		{
			if (content == null && fileInfo != null && fileInfo.Exists)
				using (Stream fileStream = fileInfo.OpenRead())
				{
					content = new byte[fileStream.Length];
					fileStream.Read(content, 0, content.Length);
				}

			return content;
		}
	}
}