///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//

using System;
using System.Collections;
using System.Diagnostics;
using System.IO;

using Pipe = Microsoft.Singularity.Io.Tty;
using FileSystem.Utils;
using Microsoft.Contracts;
using Microsoft.SingSharp.Reflection;

using Microsoft.Singularity.Applications;
using Microsoft.Singularity.Io;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.Configuration;
using Microsoft.Singularity.Channels;
[assembly: Transform(typeof(ApplicationResourceTransform))]

namespace Microsoft.Singularity.Applications
{
    [ConsoleCategory(HelpMessage="Display a screen full of text", DefaultAction=true)]
    internal class Parameters {
        [InputEndpoint("data")]
        public readonly TRef<UnicodePipeContract.Exp:READY> Stdin;

        [OutputEndpoint("data")]
        public readonly TRef<UnicodePipeContract.Imp:READY> Stdout;

        [Endpoint]
        public readonly TRef<DirectoryServiceContract.Imp:Start> nsRef;

        [StringArrayParameter( "files", HelpMessage="Files to be listed.")]
        internal string[] fileSet;

        reflective internal Parameters();

        internal int AppMain() {
            return More.AppMain(this);
        }
    }

    class More
    {
        internal static int pageCounter;
        internal static Terminal! terminal;
        internal static long fileSize;
        internal static long bytesRead;

        [ Conditional("DEBUG_MORE") ]
        static void DebugPrint(string format, params object [] args)
        {
            DebugStub.Print(String.Format(format, args));
        }

        [ Conditional("DEBUG_MORE") ]
        static void DebugWriteLine(string format, params object [] args)
        {
            DebugPrint(format, args);
            DebugStub.Print("\n");
        }

        [ Conditional("DEBUG_MORE") ]
        static void DebugReadLine()
        {
            Console.ReadLine();
        }

        internal static int AppMain(Parameters! config) {
            // constants

            //int szLineCount = 0;
            int displayfile = 0;
            int consoleWidth = 0;
            int consoleHeight = 0;
            pageCounter = 0;

            terminal = new Terminal();

            DirectoryServiceContract.Imp dsRoot = ((!)config.nsRef).Acquire();
            if (dsRoot == null) {
                throw new Exception("Unable to acquire handle to the Directory Service root");
            }

            dsRoot.RecvSuccess();

            // TODO need to dynamically get window size
            consoleHeight = 47; // allow for "activity" line on top of Singularity console....
            consoleWidth = 79;

            assume config.fileSet != null;
            string szSrcLine;
            bool ok;
            if (config.fileSet.Length <= 0) {
                //stdin
                while ((szSrcLine = Console.ReadLine()) != null) {
                    ok = PageText(szSrcLine, consoleHeight, consoleWidth, true);
                    if (!ok) break;
                }
                delete dsRoot;
                return 0;
            }

            for (displayfile = 0; displayfile < config.fileSet.Length; displayfile++) {
                string filename = config.fileSet[displayfile];
                if (filename == null) continue;

                // check that file exists
                ErrorCode error;
                FileAttributesRecord fileAttributes;
                ok  = FileUtils.GetAttributes(filename, dsRoot, out fileAttributes, out  error);
                if (ok) {
                    if (fileAttributes.Type == NodeType.IoMemory || fileAttributes.Type == NodeType.File) {
                        fileSize = fileAttributes.FileSize;

                        // Open file RO for now
                        FileStream fsInput = new FileStream(dsRoot, filename, FileMode.Open, FileAccess.Read);
                        StreamReader srInput = new StreamReader(fsInput);
                        while ((szSrcLine = srInput.ReadLine()) != null) {
                            ok = PageText(szSrcLine, consoleHeight, consoleWidth, false);
                            if (!ok) break;
                        }
                        srInput.Close();
                        fsInput.Close();

                        // Display the file by pages
                        // TODO: change PageText to return between pages so can recheck for
                        //       screen dimension changes (?)

                        if (displayfile <= config.fileSet.Length - 2) // offset by 2 due to index offset plus increment hasn't happened yet
                        {
                            Console.WriteLine("");
                            Console.Write("-- <ENTER> for next file --");
                            int key;
                            do {
                                key = Console.Read();
                                if (key == -1) {
                                    delete dsRoot;
                                    return 0;
                                }
                            } while ((char)key != '\n');
                        }
                    }
                    else if (fileAttributes.Type == NodeType.Directory) {
                        // check that it's not a directory
                        Console.WriteLine("\n{0} - is a directory.", filename);
                    }
                } // ok
                else {
                    // not a directory, but file doesn't exist, print error message
                    Console.WriteLine("\n{0} - file not found.", filename);
                }
            }
            delete dsRoot;
            return 0;
        }

        //////////////////////////////////////////////////////////////
        //  Write out prompt and wait for input
        //  After acquiring the input remove the prompt from the console
        //////////////////////////////////////////////////////////////

        static int GetInput(int PAGELENGTH, bool processingStdin)
        {
            int counter = 0;
            int key;
            if (processingStdin) {
                Console.Write("-- <more> -- ");
                key = Console.Read();
                if ((char)key == '\n' ) Console.Write("\n");
            }
            else {
                double temp = 0;
                if (fileSize != 0) {
                    temp  =  (double) (bytesRead * 100) / (double)fileSize;
                }
                else {
                    temp = 100;
                }

                Console.Write("-- <more> ({0}%) -- ", (int)temp);
                key = Console.Read();
            }

            // get rid of the -- <ENTER> line
            if ((char)key == '\n') {
                terminal.GenerateAndSendEscapeSequence(Pipe.EscapeCodes.UP);
            }
            Console.Write("\r");
            terminal.GenerateAndSendEscapeSequence(Pipe.EscapeCodes.ERASE_FROM_CURSOR);

            if (key == -1) return -1;
            switch (Char.ToLower((char)key)) {
                case 'q':
                    return -1;
                default:
                    if ((char)key == '\n') counter = PAGELENGTH ; // advance by 1
                    break;
            }
            return counter;
        }

        // PageText - display text a page at a time
        static bool PageText(string! workString,
                             int PAGELENGTH,
                             int PAGEWIDTH,
                             bool processingStdin)
        {
            string[] lines;

            int remainder = 0;
            int linesinline = 0;

            // Split the line into the requisite number of lines
            // needed based on page width

            if (workString.Length <= PAGEWIDTH) {
                lines = new string[1];
                lines[0] = workString;
            }
            else {
                int fullLines   = workString.Length / PAGEWIDTH;
                remainder       = workString.Length % PAGEWIDTH;
                linesinline     = fullLines;

                if (remainder != 0) linesinline++;
                lines = new string[linesinline];

                int pos = 0;
                for (int i = 0; i < fullLines; i++) {
                    lines[i] = workString.Substring(pos,PAGEWIDTH);
                    pos += PAGEWIDTH;
                }
                if (remainder != 0) {
                    lines[fullLines] = workString.Substring(pos);
                }
            }

            // write the lines out pausing where necessary
            for (int i = 0; i < lines.Length; i++) {
                string s = lines[i];
                assert s!= null;
                Console.WriteLine(s);
                pageCounter++;
                bytesRead += s.Length;
                if (pageCounter >= PAGELENGTH) {
                    pageCounter  = GetInput(PAGELENGTH, processingStdin);
                    if (pageCounter == -1) return false;
                }
            }
            lines = null;
            return true;
        } // end of PageText
    }
}