using System;
using System.IO;
using System.IO.Compression;
using System.Threading.Tasks;
using VersOne.Epub.Internal;

namespace VersOne.Epub
{
    public abstract class EpubContentFileRef
    {
        private readonly EpubBookRef epubBookRef;

        public EpubContentFileRef(EpubBookRef epubBookRef)
        {
            this.epubBookRef = epubBookRef;
        }

        public string FileName { get; set; }
        public EpubContentType ContentType { get; set; }
        public string ContentMimeType { get; set; }

        public byte[] ReadContentAsBytes()
        {
            return ReadContentAsBytesAsync().Result;
        }

        public async Task<byte[]> ReadContentAsBytesAsync()
        {
            ZipArchiveEntry contentFileEntry = GetContentFileEntry();
            byte[] content = new byte[(int)contentFileEntry.Length];
            using (Stream contentStream = OpenContentStream(contentFileEntry))
            using (MemoryStream memoryStream = new MemoryStream(content))
            {
                await contentStream.CopyToAsync(memoryStream).ConfigureAwait(false);
            }
            return content;
        }

        public string ReadContentAsText()
        {
            return ReadContentAsTextAsync().Result;
        }

        public async Task<string> ReadContentAsTextAsync()
        {
            using (Stream contentStream = GetContentStream())
            using (StreamReader streamReader = new StreamReader(contentStream))
            {
                return await streamReader.ReadToEndAsync().ConfigureAwait(false);
            }
        }

        public Stream GetContentStream()
        {
            return OpenContentStream(GetContentFileEntry());
        }

        private ZipArchiveEntry GetContentFileEntry()
        {
            string contentFilePath = ZipPathUtils.Combine(epubBookRef.Schema.ContentDirectoryPath, FileName);
            ZipArchiveEntry contentFileEntry = epubBookRef.EpubArchive.GetEntry(contentFilePath);
            if (contentFileEntry == null)
            {
                throw new Exception(String.Format("EPUB parsing error: file {0} not found in archive.", contentFilePath));
            }
            if (contentFileEntry.Length > Int32.MaxValue)
            {
                throw new Exception(String.Format("EPUB parsing error: file {0} is bigger than 2 Gb.", contentFilePath));
            }
            return contentFileEntry;
        }

        private Stream OpenContentStream(ZipArchiveEntry contentFileEntry)
        {
            Stream contentStream = contentFileEntry.Open();
            if (contentStream == null)
            {
                throw new Exception(String.Format("Incorrect EPUB file: content file \"{0}\" specified in manifest is not found.", FileName));
            }
            return contentStream;
        }
    }
}