encapsulate gzip logic for reuse (#654)

1 files changed, 8 insertions, 74 deletions

diff --git a/src/SMAPI.Web/Controllers/LogParserController.cs b/src/SMAPI.Web/Controllers/LogParserController.cs
index 21e4a56f..dc5895b0 100644
--- a/src/SMAPI.Web/Controllers/LogParserController.cs
+++ b/src/SMAPI.Web/Controllers/LogParserController.cs
@@ -1,13 +1,11 @@
 using System;
-using System.IO;
-using System.IO.Compression;
 using System.Linq;
-using System.Text;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Options;
 using StardewModdingAPI.Web.Framework;
 using StardewModdingAPI.Web.Framework.Clients.Pastebin;
+using StardewModdingAPI.Web.Framework.Compression;
 using StardewModdingAPI.Web.Framework.ConfigModels;
 using StardewModdingAPI.Web.Framework.LogParsing;
 using StardewModdingAPI.Web.Framework.LogParsing.Models;
@@ -27,9 +25,8 @@ namespace StardewModdingAPI.Web.Controllers
         /// <summary>The underlying Pastebin client.</summary>
         private readonly IPastebinClient Pastebin;
 
-        /// <summary>The first bytes in a valid zip file.</summary>
-        /// <remarks>See <a href="https://en.wikipedia.org/wiki/Zip_(file_format)#File_headers"/>.</remarks>
-        private const uint GzipLeadBytes = 0x8b1f;
+        /// <summary>The underlying text compression helper.</summary>
+        private readonly IGzipHelper GzipHelper;
 
 
         /*********
@@ -41,10 +38,12 @@ namespace StardewModdingAPI.Web.Controllers
         /// <summary>Construct an instance.</summary>
         /// <param name="siteConfig">The context config settings.</param>
         /// <param name="pastebin">The Pastebin API client.</param>
-        public LogParserController(IOptions<SiteConfig> siteConfig, IPastebinClient pastebin)
+        /// <param name="gzipHelper">The underlying text compression helper.</param>
+        public LogParserController(IOptions<SiteConfig> siteConfig, IPastebinClient pastebin, IGzipHelper gzipHelper)
         {
             this.Config = siteConfig.Value;
             this.Pastebin = pastebin;
+            this.GzipHelper = gzipHelper;
         }
 
         /***
@@ -84,7 +83,7 @@ namespace StardewModdingAPI.Web.Controllers
                 return this.View("Index", new LogParserModel(this.Config.LogParserUrl, null) { UploadError = "The log file seems to be empty." });
 
             // upload log
-            input = this.CompressString(input);
+            input = this.GzipHelper.CompressString(input);
             SavePasteResult result = await this.Pastebin.PostAsync(input);
 
             // handle errors
@@ -106,75 +105,10 @@ namespace StardewModdingAPI.Web.Controllers
         private async Task<PasteInfo> GetAsync(string id)
         {
             PasteInfo response = await this.Pastebin.GetAsync(id);
-            response.Content = this.DecompressString(response.Content);
+            response.Content = this.GzipHelper.DecompressString(response.Content);
             return response;
         }
 
-        /// <summary>Compress a string.</summary>
-        /// <param name="text">The text to compress.</param>
-        /// <remarks>Derived from <a href="https://stackoverflow.com/a/17993002/262123"/>.</remarks>
-        private string CompressString(string text)
-        {
-            // get raw bytes
-            byte[] buffer = Encoding.UTF8.GetBytes(text);
-
-            // compressed
-            byte[] compressedData;
-            using (MemoryStream stream = new MemoryStream())
-            {
-                using (GZipStream zipStream = new GZipStream(stream, CompressionLevel.Optimal, leaveOpen: true))
-                    zipStream.Write(buffer, 0, buffer.Length);
-
-                stream.Position = 0;
-                compressedData = new byte[stream.Length];
-                stream.Read(compressedData, 0, compressedData.Length);
-            }
-
-            // prefix length
-            byte[] zipBuffer = new byte[compressedData.Length + 4];
-            Buffer.BlockCopy(compressedData, 0, zipBuffer, 4, compressedData.Length);
-            Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, zipBuffer, 0, 4);
-
-            // return string representation
-            return Convert.ToBase64String(zipBuffer);
-        }
 
-        /// <summary>Decompress a string.</summary>
-        /// <param name="rawText">The compressed text.</param>
-        /// <remarks>Derived from <a href="https://stackoverflow.com/a/17993002/262123"/>.</remarks>
-        private string DecompressString(string rawText)
-        {
-            // get raw bytes
-            byte[] zipBuffer;
-            try
-            {
-                zipBuffer = Convert.FromBase64String(rawText);
-            }
-            catch
-            {
-                return rawText; // not valid base64, wasn't compressed by the log parser
-            }
-
-            // skip if not gzip
-            if (BitConverter.ToUInt16(zipBuffer, 4) != LogParserController.GzipLeadBytes)
-                return rawText;
-
-            // decompress
-            using (MemoryStream memoryStream = new MemoryStream())
-            {
-                // read length prefix
-                int dataLength = BitConverter.ToInt32(zipBuffer, 0);
-                memoryStream.Write(zipBuffer, 4, zipBuffer.Length - 4);
-
-                // read data
-                byte[] buffer = new byte[dataLength];
-                memoryStream.Position = 0;
-                using (GZipStream gZipStream = new GZipStream(memoryStream, CompressionMode.Decompress))
-                    gZipStream.Read(buffer, 0, buffer.Length);
-
-                // return original string
-                return Encoding.UTF8.GetString(buffer);
-            }
-        }
     }
 }