using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Security.Cryptography;

using Nancy;

using Caching;

namespace DSTHashRepository {

public class HashRepositoryModule : Nancy.NancyModule {

private LRUCache<string, string> HashCache = new LRUCache<string, string>(1024, 24);

private string ToHashName(string rawHash) => String.Concat(rawHash.Where(c => c != '/' && c != '.' && c != '\\'));//no navigation characters

private string FilesDir => Path.Combine(".", "files");

private string ToFilePath(string hashName) => Path.Combine(FilesDir, hashName);

private string ToHashPath(string rawHash) {

string hex;

if (HashCache.TryGetValue(rawHash, out hex)) {

return hex;

}

byte[] hashHash;

using (var sha2 = new SHA256Managed()) {

hashHash = sha2.ComputeHash(Encoding.UTF8.GetBytes(rawHash));

}

hex = BytesToHex(hashHash);

HashCache.Add(rawHash, hex);

return hex;

}

public static string BytesToHex(byte[] bytes) {

var sb = new StringBuilder(bytes.Length * 2);

foreach (var b in bytes) {

sb.AppendFormat("{0:x2}", b);

}

return sb.ToString();

}

public HashRepositoryModule(IHashRepositoryConfig config) {

if (!Directory.Exists(FilesDir)) {

Directory.CreateDirectory(FilesDir);

}

Get["/"] = _ => "DST Hash Repository Prototype";

Head["/{hash*}"] = _ => {

var hashPath = ToHashPath((string)_.hash);

Console.WriteLine("HEAD: {0}", hashPath);

if (!File.Exists(hashPath)) {

return HttpStatusCode.NotFound;

}

return HttpStatusCode.OK;

};

Get["/{hash*}"] = _ => {

var hashPath = ToHashPath((string)_.hash);

Console.WriteLine("GET: {0}", hashPath);

if (!File.Exists(hashPath)) {

return HttpStatusCode.NotFound;

}

return Response.FromStream(File.OpenRead(hashPath), "application/binary");

};

Put["/{hash*}", true] = async (_, ct) => {

var hashPath = ToHashPath((string)_.hash);

var secretHeader = Request.Headers["secret"].FirstOrDefault();

if (!config.CheckCredentials("", secretHeader)) {

Console.WriteLine("PUT|AUTHFAIL: {0}", hashPath);

return HttpStatusCode.Forbidden;

}

Console.WriteLine("PUT: {0}", hashPath);

using (var destFile = File.Create(hashPath)) {

await Request.Body.CopyToAsync(destFile);

}

return HttpStatusCode.OK;

};

Delete["/{hash*}"] = _ => {

var hashPath = ToHashPath((string)_.hash);

var secretHeader = Request.Headers["secret"].FirstOrDefault();

if (!config.CheckCredentials("", secretHeader)) {

Console.WriteLine("DELETE|AUTHFAIL: {0}", hashPath);

return HttpStatusCode.Forbidden;

}

Console.WriteLine("DELETE: {0}", hashPath);

if (!File.Exists(hashPath)) {

return HttpStatusCode.NotFound;

}

File.Delete(hashPath);

return HttpStatusCode.OK;

};

}

}

}