/*
	Relay -- a tool to record and play Quake2 demos
	Copyright (C) 2000 Conor Davis

	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.

	Conor Davis
	cedavis@planetquake.com
*/

#include <string.h>
#include <assert.h>

#include "shared.h"
#include "block.h"
#include "endian.h"
#include "q2defines.h"

//
// generic block functions
//

void BlockInit(block_t *block, char *buffer, size_t size)
{
	block->buffer = buffer;
	block->size = size;
	block->readoffset = 0;
	block->writeoffset = 0;
	block->writelen = 0;
	block->readoverflow = false;
	block->writeoverflow = false;
}

void BlockRewind(block_t *block)
{
	block->readoffset = 0;
	block->writeoffset = 0;
	block->writelen = 0;
	block->readoverflow = false;
	block->writeoverflow = false;
}

void BlockRewindRead(block_t *block)
{
	block->readoffset = 0;
	block->readoverflow = false;
}

qboolean ReadOverflow(block_t *block)
{
	return block->readoverflow;
}

qboolean WriteOverflow(block_t *block)
{
	return block->writeoverflow;
}

// CheckRead
// Determines whether it is safe to read len bytes
// from block
static qboolean CheckRead(block_t *block, size_t len)
{
	if (block->readoffset + len > block->writeoffset)
	{
		block->readoverflow = true;
		return false;
	}

	return true;
}

// CheckWrite
// Determines whether it is safe to write len bytes
// to block
static qboolean CheckWrite(block_t *block, size_t len)
{
	block->writelen += len;
	if (block->writeoffset + len > block->size)
	{
		block->writeoverflow = true;
		return false;
	}

	return true;
}

const char *BlockRead(block_t *block, char *buffer, size_t len)
{
	if (!CheckRead(block, len))
		return NULL;

	if (buffer)
		memcpy(buffer, block->buffer + block->readoffset, len);

	block->readoffset += len;
	return block->buffer + block->readoffset - len;
}

void BlockWrite(block_t *block, const char *buffer, size_t len)
{
	if (!CheckWrite(block, len))
		return;

	memcpy(block->buffer + block->writeoffset, buffer, len);
	block->writeoffset += len;
}

const char *BlockCopy(block_t *dest, block_t *src, size_t len)
{
	if (!CheckRead(src, len))
		return NULL;

	if (!CheckWrite(dest, len))
		return NULL;

	memcpy(dest->buffer + dest->writeoffset, src->buffer + src->readoffset, len);
	src->readoffset += len;
	dest->writeoffset += len;

	return dest->buffer + dest->writeoffset - len;
}

//
// low-level read/write functions
//

char ReadChar(block_t *block)
{
	char a;

	if (!CheckRead(block, 1))
		return 0;

	a = *(char *)(block->buffer + block->readoffset);
	block->readoffset++;

	return a;
}

void WriteChar(block_t *block, char a)
{
	if (!CheckWrite(block, 1))
		return;

	*(char *)(block->buffer + block->writeoffset) = a;
	block->writeoffset++;
}

unsigned char ReadByte(block_t *block)
{
	unsigned char a;

	if (!CheckRead(block, 1))
		return 0;

	a = *(unsigned char *)(block->buffer + block->readoffset);
	block->readoffset++;

	return a;
}

void WriteByte(block_t *block, unsigned char a)
{
	if (!CheckWrite(block, 1))
		return;

	*(unsigned char *)(block->buffer + block->writeoffset) = a;
	block->writeoffset++;
}

short ReadShort(block_t *block)
{
	short a;

	if (!CheckRead(block, 2))
		return 0;

	a = *(short *)(block->buffer + block->readoffset);
	block->readoffset += 2;

	return LittleShort(a);
}

void WriteShort(block_t *block, short a)
{
	if (!CheckWrite(block, 2))
		return;

	*(short *)(block->buffer + block->writeoffset) = LittleShort(a);
	block->writeoffset += 2;
}

long ReadLong(block_t *block)
{
	long a;

	if (!CheckRead(block, 4))
		return 0;

	a = *(long *)(block->buffer + block->readoffset);
	block->readoffset += 4;

	return LittleLong(a);
}

void WriteLong(block_t *block, long a)
{
	if (!CheckWrite(block, 4))
		return;

	*(long *)(block->buffer + block->writeoffset) = LittleLong(a);
	block->writeoffset += 4;
}

unsigned long ReadULong(block_t *block)
{
	unsigned long a;

	if (!CheckRead(block, 4))
		return 0;

	a = *(unsigned long *)(block->buffer + block->readoffset);
	block->readoffset += 4;

	return LittleLong(a);
}

void WriteULong(block_t *block, unsigned long a)
{
	if (!CheckWrite(block, 4))
		return;

	*(unsigned long *)(block->buffer + block->writeoffset) = LittleLong(a);
	block->writeoffset += 4;
}

const char *ReadString(block_t *block)
{
	char	*start;

	start = block->buffer + block->readoffset;
	while (ReadChar(block))
		;

	if (ReadOverflow(block))
		return "";

	return start;
}

void WriteString(block_t *block, const char *string)
{
	size_t len;

	len = strlen(string) + 1;
	if (!CheckWrite(block, len))
		return;

	strcpy(block->buffer + block->writeoffset, string);
	block->writeoffset += len;
}

//
// higher-level functions that call
// the above functions
//

float ReadFloat(block_t *block)
{
	union {int l; float f;} a;

	a.l = ReadLong(block);
	return a.f;
}

float ReadAngle(block_t *block)
{
	return (float)ReadChar(block) / 256 * 360;
}

void WriteAngle(block_t *block, float a)
{
	WriteChar(block, (char)(a * 256 / 360));
}

float ReadAngle16(block_t *block)
{
	return (float)ReadShort(block) / 65536 * 360;
}

void WriteAngle16(block_t *block, float a)
{
	WriteShort(block, (short)(a * 65535 / 360));
}

float ReadCoord(block_t *block)
{
	return (float)ReadShort(block) * 0.125F;
}

void WriteCoord(block_t *block, float a)
{
	WriteShort(block, (short)(a * 8));
}

float *ReadPosition(block_t *block, float *vec)
{
	vec[0] = ReadCoord(block);
	vec[1] = ReadCoord(block);
	vec[2] = ReadCoord(block);

	return vec;
}

void WritePosition(block_t *block, const float *vec)
{
	WriteCoord(block, vec[0]);
	WriteCoord(block, vec[1]);
	WriteCoord(block, vec[2]);
}

short *ReadShortPosition(block_t *block, short *vec)
{
	vec[0] = ReadShort(block);
	vec[1] = ReadShort(block);
	vec[2] = ReadShort(block);

	return vec;
}

void WriteShortPosition(block_t *block, const short *vec)
{
	WriteShort(block, vec[0]);
	WriteShort(block, vec[1]);
	WriteShort(block, vec[2]);
}

#define DM2_NUMVERTEXNORMALS 162
float avertexnormals[3*DM2_NUMVERTEXNORMALS] =
{
	-0.525731027, 0, 0.850651026,
	-0.442862988, 0.238856003, 0.864188015,
	-0.295242012, 0, 0.955422997,
	-0.309017003, 0.5, 0.809017003,
	-0.162459999, 0.26286599, 0.951056004,
	0, 0, 1,
	0, 0.850651026, 0.525731027,
	-0.147621006, 0.71656698, 0.681717992,
	0.147621006, 0.71656698, 0.681717992,
	0, 0.525731027, 0.850651026,
	0.309017003, 0.5, 0.809017003,
	0.525731027, 0, 0.850651026,
	0.295242012, 0, 0.955422997,
	0.442862988, 0.238856003, 0.864188015,
	0.162459999, 0.26286599, 0.951056004,
	-0.681717992, 0.147621006, 0.71656698,
	-0.809017003, 0.309017003, 0.5,
	-0.587785006, 0.425325006, 0.688190997,
	-0.850651026, 0.525731027, 0,
	-0.864188015, 0.442862988, 0.238856003,
	-0.71656698, 0.681717992, 0.147621006,
	-0.688190997, 0.587785006, 0.425325006,
	-0.5, 0.809017003, 0.309017003,
	-0.238856003, 0.864188015, 0.442862988,
	-0.425325006, 0.688190997, 0.587785006,
	-0.71656698, 0.681717992, -0.147621006,
	-0.5, 0.809017003, -0.309017003,
	-0.525731027, 0.850651026, 0,
	0, 0.850651026, -0.525731027,
	-0.238856003, 0.864188015, -0.442862988,
	0, 0.955422997, -0.295242012,
	-0.26286599, 0.951056004, -0.162459999,
	0, 1, 0,
	0, 0.955422997, 0.295242012,
	-0.26286599, 0.951056004, 0.162459999,
	0.238856003, 0.864188015, 0.442862988,
	0.26286599, 0.951056004, 0.162459999,
	0.5, 0.809017003, 0.309017003,
	0.238856003, 0.864188015, -0.442862988,
	0.26286599, 0.951056004, -0.162459999,
	0.5, 0.809017003, -0.309017003,
	0.850651026, 0.525731027, 0,
	0.71656698, 0.681717992, 0.147621006,
	0.71656698, 0.681717992, -0.147621006,
	0.525731027, 0.850651026, 0,
	0.425325006, 0.688190997, 0.587785006,
	0.864188015, 0.442862988, 0.238856003,
	0.688190997, 0.587785006, 0.425325006,
	0.809017003, 0.309017003, 0.5,
	0.681717992, 0.147621006, 0.71656698,
	0.587785006, 0.425325006, 0.688190997,
	0.955422997, 0.295242012, 0,
	1, 0, 0,
	0.951056004, 0.162459999, 0.26286599,
	0.850651026, -0.525731027, 0,
	0.955422997, -0.295242012, 0,
	0.864188015, -0.442862988, 0.238856003,
	0.951056004, -0.162459999, 0.26286599,
	0.809017003, -0.309017003, 0.5,
	0.681717992, -0.147621006, 0.71656698,
	0.850651026, 0, 0.525731027,
	0.864188015, 0.442862988, -0.238856003,
	0.809017003, 0.309017003, -0.5,
	0.951056004, 0.162459999, -0.26286599,
	0.525731027, 0, -0.850651026,
	0.681717992, 0.147621006, -0.71656698,
	0.681717992, -0.147621006, -0.71656698,
	0.850651026, 0, -0.525731027,
	0.809017003, -0.309017003, -0.5,
	0.864188015, -0.442862988, -0.238856003,
	0.951056004, -0.162459999, -0.26286599,
	0.147621006, 0.71656698, -0.681717992,
	0.309017003, 0.5, -0.809017003,
	0.425325006, 0.688190997, -0.587785006,
	0.442862988, 0.238856003, -0.864188015,
	0.587785006, 0.425325006, -0.688190997,
	0.688190997, 0.587785006, -0.425325006,
	-0.147621006, 0.71656698, -0.681717992,
	-0.309017003, 0.5, -0.809017003,
	0, 0.525731027, -0.850651026,
	-0.525731027, 0, -0.850651026,
	-0.442862988, 0.238856003, -0.864188015,
	-0.295242012, 0, -0.955422997,
	-0.162459999, 0.26286599, -0.951056004,
	0, 0, -1,
	0.295242012, 0, -0.955422997,
	0.162459999, 0.26286599, -0.951056004,
	-0.442862988, -0.238856003, -0.864188015,
	-0.309017003, -0.5, -0.809017003,
	-0.162459999, -0.26286599, -0.951056004,
	0, -0.850651026, -0.525731027,
	-0.147621006, -0.71656698, -0.681717992,
	0.147621006, -0.71656698, -0.681717992,
	0, -0.525731027, -0.850651026,
	0.309017003, -0.5, -0.809017003,
	0.442862988, -0.238856003, -0.864188015,
	0.162459999, -0.26286599, -0.951056004,
	0.238856003, -0.864188015, -0.442862988,
	0.5, -0.809017003, -0.309017003,
	0.425325006, -0.688190997, -0.587785006,
	0.71656698, -0.681717992, -0.147621006,
	0.688190997, -0.587785006, -0.425325006,
	0.587785006, -0.425325006, -0.688190997,
	0, -0.955422997, -0.295242012,
	0, -1, 0,
	0.26286599, -0.951056004, -0.162459999,
	0, -0.850651026, 0.525731027,
	0, -0.955422997, 0.295242012,
	0.238856003, -0.864188015, 0.442862988,
	0.26286599, -0.951056004, 0.162459999,
	0.5, -0.809017003, 0.309017003,
	0.71656698, -0.681717992, 0.147621006,
	0.525731027, -0.850651026, 0,
	-0.238856003, -0.864188015, -0.442862988,
	-0.5, -0.809017003, -0.309017003,
	-0.26286599, -0.951056004, -0.162459999,
	-0.850651026, -0.525731027, 0,
	-0.71656698, -0.681717992, -0.147621006,
	-0.71656698, -0.681717992, 0.147621006,
	-0.525731027, -0.850651026, 0,
	-0.5, -0.809017003, 0.309017003,
	-0.238856003, -0.864188015, 0.442862988,
	-0.26286599, -0.951056004, 0.162459999,
	-0.864188015, -0.442862988, 0.238856003,
	-0.809017003, -0.309017003, 0.5,
	-0.688190997, -0.587785006, 0.425325006,
	-0.681717992, -0.147621006, 0.71656698,
	-0.442862988, -0.238856003, 0.864188015,
	-0.587785006, -0.425325006, 0.688190997,
	-0.309017003, -0.5, 0.809017003,
	-0.147621006, -0.71656698, 0.681717992,
	-0.425325006, -0.688190997, 0.587785006,
	-0.162459999, -0.26286599, 0.951056004,
	0.442862988, -0.238856003, 0.864188015,
	0.162459999, -0.26286599, 0.951056004,
	0.309017003, -0.5, 0.809017003,
	0.147621006, -0.71656698, 0.681717992,
	0, -0.525731027, 0.850651026,
	0.425325006, -0.688190997, 0.587785006,
	0.587785006, -0.425325006, 0.688190997,
	0.688190997, -0.587785006, 0.425325006,
	-0.955422997, 0.295242012, 0,
	-0.951056004, 0.162459999, 0.26286599,
	-1, 0, 0,
	-0.850651026, 0, 0.525731027,
	-0.955422997, -0.295242012, 0,
	-0.951056004, -0.162459999, 0.26286599,
	-0.864188015, 0.442862988, -0.238856003,
	-0.951056004, 0.162459999, -0.26286599,
	-0.809017003, 0.309017003, -0.5,
	-0.864188015, -0.442862988, -0.238856003,
	-0.951056004, -0.162459999, -0.26286599,
	-0.809017003, -0.309017003, -0.5,
	-0.681717992, 0.147621006, -0.71656698,
	-0.681717992, -0.147621006, -0.71656698,
	-0.850651026, 0, -0.525731027,
	-0.688190997, 0.587785006, -0.425325006,
	-0.587785006, 0.425325006, -0.688190997,
	-0.425325006, 0.688190997, -0.587785006,
	-0.425325006, -0.688190997, -0.587785006,
	-0.587785006, -0.425325006, -0.688190997,
	-0.688190997, -0.587785006, -0.425325006,
};

float *ReadDir(block_t *block, float *a)
{
	int code;
	
	code = ReadByte(block);
	if (code >= DM2_NUMVERTEXNORMALS)
		assert(0);

	a[0] = avertexnormals[3 * code + 0];
	a[1] = avertexnormals[3 * code + 1];
	a[2] = avertexnormals[3 * code + 2];
	
	return a;
}

void WriteDir(block_t *block, const float *a)
{
	int 	j, maxdotindex;
	float	dot, maxdot;
	
	maxdot = -999999.0;
	maxdotindex = -1;
	
	for (j = 0; j < DM2_NUMVERTEXNORMALS; j++)
	{
		dot = avertexnormals[3*j + 0] * a[0] +
			avertexnormals[3*j + 1] * a[1] +
			avertexnormals[3*j + 2] * a[2];

		if (dot > maxdot)
		{
			maxdot = dot;
			maxdotindex = j;
		}
	}
	
	WriteByte(block, (byte)maxdotindex);
}

float ReadBlend(block_t *block)
{
	return (float)ReadByte(block) / 255;
}

void WriteBlend(block_t *block, float a)
{
	WriteByte(block, (byte)(a * 255));
}

float *ReadBlendVec(block_t *block, float *a)
{
	a[0] = ReadBlend(block);
	a[1] = ReadBlend(block);
	a[2] = ReadBlend(block);
	a[3] = ReadBlend(block);

	return a;
}

void WriteBlendVec(block_t *block, const float *a)
{
	WriteBlend(block, a[0]);
	WriteBlend(block, a[1]);
	WriteBlend(block, a[2]);
	WriteBlend(block, a[3]);
}

float ReadOffset(block_t *block)
{
	return (float)ReadChar(block) * 0.25F;
}

void WriteOffset(block_t *block, float a)
{
	WriteChar(block, (char)(a * 4));
}

float *ReadOffsetVec(block_t *block, float *a)
{
	a[0] = ReadOffset(block);
	a[1] = ReadOffset(block);
	a[2] = ReadOffset(block);

	return a;
}

void WriteOffsetVec(block_t *block, const float *a)
{
	WriteOffset(block, a[0]);
	WriteOffset(block, a[1]);
	WriteOffset(block, a[2]);
}