///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  Note:   The Spew web app (serves files and supports browsing)
//

using System;
using System.Collections;
using System.Diagnostics;
using Microsoft.SingSharp;
using Microsoft.SingSharp.Runtime;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.WebApps;
using Microsoft.Singularity.WebApps.Contracts;
using System.Text;
using System.Web;
using FileSystem.Utils;

namespace Microsoft.Singularity.WebApps
{
    public class SpewWebApp : IWebApp
    {
        private const string RepeatPattern = "Here is a repeating string of text that serves as content. ";

        public void ProcessRequest(IHttpRequest! request)
        {
            string query = request.GetQueryString();
            int numBytes = 0, chunkSize = 5840; // 1460 * 4

            ExtractQueryParamNumValue("numBytes", query, ref numBytes);
            ExtractQueryParamNumValue("chunkSize", query, ref chunkSize);

            request.SendStatus(200, "OK");
            request.SendHeader("Content-type", "text/plain");

            if (numBytes == 0) {
                request.SendBodyData(Encoding.ASCII.GetBytes("Specify a 'numBytes' query param, and optionally a 'chunkSize' query param!"));
                request.Done();

            }
            else {
                byte[]! in ExHeap buf;
                int bytesWritten = 0, patternLength = RepeatPattern.Length;

                while (bytesWritten < numBytes) {
                    int bytesLeft = numBytes - bytesWritten;
                    int thisPass = chunkSize < bytesLeft ? chunkSize : bytesLeft;
                    buf = new[ExHeap] byte[thisPass];

                    for (int i = 0; i < thisPass; i++) {
                        buf[i] = (byte)RepeatPattern[i % patternLength];
                    }

                    request.SendBodyData(buf);
                    bytesWritten += thisPass;
                }

                request.Done();
            }
        }

        private bool ExtractQueryParamNumValue(string! paramName, string queryString, ref int outVal)
        {
            if (queryString == null) {
                return false;
            }

            int start = queryString.IndexOf(paramName + "=");

            if (start == -1) {
                return false;
            }

            start += paramName.Length + 1;
            int end = queryString.IndexOf("&", start);
            string val;

            if (end == -1) {
                val = queryString.Substring(start);
            }
            else {
                val = queryString.Substring(start, end - start);
            }

            try {
                outVal = Int32.Parse(val);
                return true;
            }
            catch (Exception) {
                return false;
            }
        }


        // ======================================================
        // The code below gets used when this webapp is compiled
        // to a stand-alone executable
        public static void Main(string[]! args)
        {
            Endpoint * in ExHeap ep = Process.GetStartupEndpoint(0);
            WebAppContract.Exp conn = ep as WebAppContract.Exp;
            if (conn == null) {
                // Wrong contract type!
                delete ep;
                return;
            }

            conn.SendWebAppReady();

            SpewWebApp webApp = new SpewWebApp();
            Driver.ServiceChannel(webApp, conn);
            delete conn;
        }
    }
}