// Emacs style mode select   -*- C++ -*-
//-----------------------------------------------------------------------------
//
// Copyright(C) 1993-1996 Id Software, Inc.
// Copyright(C) 2005 Simon Howard
// Copyright(C) 2006 Ben Ryves 2006
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
// 02111-1307, USA.
//
// mus2mid.c - Ben Ryves 2006 - http://benryves.com - benryves@benryves.com
// Use to convert a MUS file into a single track, type 0 MIDI file.

// e6y
// All tabs are replaced with spaces.
// Fixed eol style of files.

#include <stdio.h>

#include "doomtype.h"
#include "m_swap.h"

#include "memio.h"
#include "mus2mid.h"

// MUS event codes
typedef enum
{
  mus_releasekey = 0x00,
  mus_presskey = 0x10,
  mus_pitchwheel = 0x20,
  mus_systemevent = 0x30,
  mus_changecontroller = 0x40,
  mus_scoreend = 0x60
} musevent;

// MIDI event codes
typedef enum
{
  midi_releasekey = 0x80,
  midi_presskey = 0x90,
  midi_aftertouchkey = 0xA0,
  midi_changecontroller = 0xB0,
  midi_changepatch = 0xC0,
  midi_aftertouchchannel = 0xD0,
  midi_pitchwheel = 0xE0
} midievent;


// Structure to hold MUS file header
typedef struct
{
  byte id[4];
  unsigned short scorelength;
  unsigned short scorestart;
  unsigned short primarychannels;
  unsigned short secondarychannels;
  unsigned short instrumentcount;
} musheader;

// Standard MIDI type 0 header + track header
static byte midiheader[] =
{
  'M', 'T', 'h', 'd',     // Main header
  0x00, 0x00, 0x00, 0x06, // Header size
  0x00, 0x00,             // MIDI type (0)
  0x00, 0x01,             // Number of tracks
  0x00, 0x46,             // Resolution
  'M', 'T', 'r', 'k',    // Start of track
  0x00, 0x00, 0x00, 0x00  // Placeholder for track length
};

// Cached channel velocities
static byte channelvelocities[] =
{
  127, 127, 127, 127, 127, 127, 127, 127,
  127, 127, 127, 127, 127, 127, 127, 127
};

// Timestamps between sequences of MUS events

static unsigned int queuedtime = 0;

// Counter for the length of the track

static unsigned int tracksize;

static byte mus2midi_translation[] =
{
  0x00, 0x20, 0x01, 0x07, 0x0A, 0x0B, 0x5B, 0x5D,
  0x40, 0x43, 0x78, 0x7B, 0x7E, 0x7F, 0x79
};

// Write timestamp to a MIDI file.

static boolean midi_writetime(unsigned int time, MEMFILE *midioutput)
{
  unsigned int buffer = time & 0x7F;
  byte writeval;

  while ((time >>= 7) != 0)
  {
    buffer <<= 8;
    buffer |= ((time & 0x7F) | 0x80);
  }

  for (;;)
  {
    writeval = (byte)(buffer & 0xFF);

    if (mem_fwrite(&writeval, 1, 1, midioutput) != 1)
    {
      return true;
    }

    ++tracksize;

    if ((buffer & 0x80) != 0)
    {
      buffer >>= 8;
    }
    else
    {
      queuedtime = 0;
      return false;
    }
  }
}


// Write the end of track marker
static boolean midi_writeendtrack(MEMFILE *midioutput)
{
  byte endtrack[] = {0xFF, 0x2F, 0x00};

  if (midi_writetime(queuedtime, midioutput))
  {
    return true;
  }

  if (mem_fwrite(endtrack, 1, 3, midioutput) != 3)
  {
    return true;
  }

  tracksize += 3;
  return false;
}

// Write a key press event
static boolean midi_writepresskey(byte channel, byte key,
                                  byte velocity, MEMFILE *midioutput)
{
  byte working = midi_presskey | channel;

  if (midi_writetime(queuedtime, midioutput))
  {
    return true;
  }

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  working = key & 0x7F;

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  working = velocity & 0x7F;

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  tracksize += 3;

  return false;
}

// Write a key release event
static boolean midi_writereleasekey(byte channel, byte key,
                                    MEMFILE *midioutput)
{
  byte working = midi_releasekey | channel;

  if (midi_writetime(queuedtime, midioutput))
  {
    return true;
  }

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  working = key & 0x7F;

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  working = 0;

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  tracksize += 3;

  return false;
}

// Write a pitch wheel/bend event
static boolean midi_writepitchwheel(byte channel, short wheel,
                                    MEMFILE *midioutput)
{
  byte working = midi_pitchwheel | channel;

  if (midi_writetime(queuedtime, midioutput))
  {
    return true;
  }

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  working = wheel & 0x7F;

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  working = (wheel >> 7) & 0x7F;

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  tracksize += 3;
  return false;
}

// Write a patch change event
static boolean midi_writechangepatch(byte channel, byte patch,
                                     MEMFILE *midioutput)
{
  byte working = midi_changepatch | channel;

  if (midi_writetime(queuedtime, midioutput))
  {
    return true;
  }

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  working = patch & 0x7F;

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  tracksize += 2;

  return false;
}



// Write a valued controller change event
static boolean midi_writechangecontroller_valued(byte channel,
                                                 byte control,
                                                 byte value,
                                                 MEMFILE *midioutput)
{
  byte working = midi_changecontroller | channel;

  if (midi_writetime(queuedtime, midioutput))
  {
    return true;
  }

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  working = control & 0x7F;

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }
  // Quirk in vanilla DOOM? MUS controller values should be
  // 7-bit, not 8-bit.

  working = value;// & 0x7F;

  // Fix on said quirk to stop MIDI players from complaining that
  // the value is out of range:

  if (working & 0x80)
  {
    working = 0x7F;
  }

  if (mem_fwrite(&working, 1, 1, midioutput) != 1)
  {
    return true;
  }

  tracksize += 3;

  return false;
}

// Write a valueless controller change event
static boolean midi_writechangecontroller_valueless(byte channel,
                                                    byte control,
                                                    MEMFILE *midioutput)
{
  return midi_writechangecontroller_valued(channel, control, 0,
              midioutput);
}

static boolean read_musheader(MEMFILE *file, musheader *header)
{
  boolean result;

  result = (mem_fread(&header->id, sizeof(byte), 4, file) == 4)
              && (mem_fread(&header->scorelength, sizeof(short), 1, file) == 1)
              && (mem_fread(&header->scorestart, sizeof(short), 1, file) == 1)
              && (mem_fread(&header->primarychannels, sizeof(short), 1, file) == 1)
              && (mem_fread(&header->secondarychannels, sizeof(short), 1, file) == 1)
              && (mem_fread(&header->instrumentcount, sizeof(short), 1, file) == 1);

  if (result)
  {
    header->scorelength = SHORT(header->scorelength);
    header->scorestart = SHORT(header->scorestart);
    header->primarychannels = SHORT(header->primarychannels);
    header->secondarychannels = SHORT(header->secondarychannels);
    header->instrumentcount = SHORT(header->instrumentcount);
  }

  return result;
}


// Read a MUS file from a stream (musinput) and output a MIDI file to
// a stream (midioutput).
//
// Returns 0 on success or 1 on failure.

boolean mus2mid(MEMFILE *musinput, MEMFILE *midioutput)
{
  // Header for the MUS file
  musheader musfileheader;

  // Descriptor for the current MUS event
  byte eventdescriptor;
  byte channel; // Channel number
  musevent event;


  // Bunch of vars read from MUS lump
  byte key;
  byte controllernumber;
  byte controllervalue;

  // Buffer used for MIDI track size record
  byte tracksizebuffer[4];

  // Flag for when the score end marker is hit.
  int hitscoreend = 0;

  // Temp working byte
  byte working;
  // Used in building up time delays
  unsigned int timedelay;

  // Grab the header

  if (!read_musheader(musinput, &musfileheader))
  {
    return true;
  }

#ifdef CHECK_MUS_HEADER
  // Check MUS header
  if (musfileheader.id[0] != 'M'
   || musfileheader.id[1] != 'U'
   || musfileheader.id[2] != 'S'
   || musfileheader.id[3] != 0x1A)
  {
    return true;
  }
#endif

  // Seek to where the data is held
  if (mem_fseek(musinput, (long)musfileheader.scorestart, SEEK_SET) != 0)
  {
    return true;
  }

  // So, we can assume the MUS file is faintly legit. Let's start
  // writing MIDI data...

  mem_fwrite(midiheader, 1, sizeof(midiheader), midioutput);
  tracksize = 0;

  // Now, process the MUS file:
  while (!hitscoreend)
  {
    // Handle a block of events:

    while (!hitscoreend)
    {
      // Fetch channel number and event code:

      if (mem_fread(&eventdescriptor, 1, 1, musinput) != 1)
      {
        return true;
      }

      channel = eventdescriptor & 0x0F;
      event = eventdescriptor & 0x70;

      // Swap channels 15 and 9.
      // MIDI channel 9 = percussion.
      // MUS channel 15 = percussion.

      if (channel == 15)
      {
        channel = 9;
      }
      else if (channel == 9)
      {
        channel = 15;
      }

      switch (event)
      {
        case mus_releasekey:
          if (mem_fread(&key, 1, 1, musinput) != 1)
          {
            return true;
          }

          if (midi_writereleasekey(channel, key, midioutput))
          {
            return true;
          }

          break;

        case mus_presskey:
          if (mem_fread(&key, 1, 1, musinput) != 1)
          {
            return true;
          }

          if (key & 0x80)
          {
            if (mem_fread(&channelvelocities[channel], 1, 1, musinput) != 1)
            {
              return true;
            }

            channelvelocities[channel] &= 0x7F;
          }

          if (midi_writepresskey(channel, key, channelvelocities[channel], midioutput))
          {
            return true;
          }

          break;

        case mus_pitchwheel:
          if (mem_fread(&key, 1, 1, musinput) != 1)
          {
            break;
          }
          if (midi_writepitchwheel(channel, (short)(key * 64), midioutput))
          {
            return true;
          }

          break;

        case mus_systemevent:
          if (mem_fread(&controllernumber, 1, 1, musinput) != 1)
          {
            return true;
          }
          if (controllernumber < 10 || controllernumber > 14)
          {
            return true;
          }

          if (midi_writechangecontroller_valueless(channel, mus2midi_translation[controllernumber], midioutput))
          {
            return true;
          }

          break;

        case mus_changecontroller:
          if (mem_fread(&controllernumber, 1, 1, musinput) != 1)
          {
            return true;
          }

          if (mem_fread(&controllervalue, 1, 1, musinput) != 1)
          {
            return true;
          }

          if (controllernumber == 0)
          {
            if (midi_writechangepatch(channel, controllervalue, midioutput))
            {
              return true;
            }
          }
          else
          {
            if (controllernumber < 1 || controllernumber > 9)
            {
              return true;
            }

            if (midi_writechangecontroller_valued(channel, mus2midi_translation[controllernumber], controllervalue, midioutput))
            {
              return true;
            }
          }

          break;

        case mus_scoreend:
          hitscoreend = 1;
          break;

        default:
          return true;
          break;
      }

      if (eventdescriptor & 0x80)
      {
        break;
      }
    }
    // Now we need to read the time code:
    if (!hitscoreend)
    {
      timedelay = 0;
      for (;;)
      {
        if (mem_fread(&working, 1, 1, musinput) != 1)
        {
          return true;
        }

        timedelay = timedelay * 128 + (working & 0x7F);
        if ((working & 0x80) == 0)
        {
          break;
        }
      }
      queuedtime += timedelay;
    }
  }

  // End of track
  if (midi_writeendtrack(midioutput))
  {
    return true;
  }

  // Write the track size into the stream
  if (mem_fseek(midioutput, 18, SEEK_SET))
  {
    return true;
  }

  tracksizebuffer[0] = (tracksize >> 24) & 0xff;
  tracksizebuffer[1] = (tracksize >> 16) & 0xff;
  tracksizebuffer[2] = (tracksize >> 8) & 0xff;
  tracksizebuffer[3] = tracksize & 0xff;

  if (mem_fwrite(tracksizebuffer, 1, 4, midioutput) != 4)
  {
    return true;
  }

  return false;
}