/*
 *	Copyright (c) 2024 Scott Duensing, scott@kangaroopunch.com
 *
 *	Permission is hereby granted, free of charge, to any person obtaining a copy
 *	of this software and associated documentation files (the "Software"), to deal
 *	in the Software without restriction, including without limitation the rights
 *	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *	copies of the Software, and to permit persons to whom the Software is
 *	furnished to do so, subject to the following conditions:
 *
 *	The above copyright notice and this permission notice shall be included in
 *	all copies or substantial portions of the Software.
 *
 *	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 *	SOFTWARE.
 */


#include "bitmap.h"
#include "dma.h"


static int16_t  _MAX_X       = 320;
static int16_t  _MAX_Y       = 240;
static uint32_t _BITMAP_BASE = 0x10000;
static byte     _color       = 255;


char error;


void clearBitmap(void) {
	dmaFill(_BITMAP_BASE, (uint32_t)_MAX_X * (uint32_t)_MAX_Y, _color);
}


void defineGraphicsColor(byte slot, byte r, byte g, byte b) {
	byte  mmu = PEEK(MMU_IO_CTRL);  // Get current MMU state.
	byte *write;

	POKE(MMU_IO_CTRL, MMU_IO_PAGE_1);  // Swap I/O page 1 into bank 6.

	write = (byte *)VKY_GR_CLUT_0 + slot * 4;
	*write++ = b;
	*write++ = g;
	*write++ = r;
	*write++ = 0xff;

	POKE(MMU_IO_CTRL, mmu);  // Restore MMU state.
}


void getBitmapResolution(int16_t *x, int16_t *y) {
	*x = _MAX_X;
	*y = _MAX_Y;
}


void line(int16_t x1, int16_t y1, int16_t x2, int16_t y2) {
	int16_t x;
	int16_t y;
	int16_t dx;
	int16_t dy;
	int16_t incX;
	int16_t incY;
	int16_t balance;

	if (x2 >= x1) {
		dx = x2 - x1;
		incX = 1;
	} else {
		dx = x1 - x2;
		incX = -1;
	}

	if (y2 >= y1) {
		dy = y2 - y1;
		incY = 1;
	} else {
		dy = y1 - y2;
		incY = -1;
	}

	x = x1;
	y = y1;

	if (dx >= dy) {
		dy <<= 1;
		balance = dy - dx;
		dx <<= 1;
		while (x != x2) {
			putpixel(x, y);
			if (balance >= 0) {
				y += incY;
				balance -= dx;
			}
			balance += dy;
			x += incX;
		}
		putpixel(x, y);
	} else {
		dx <<= 1;
		balance = dx - dy;
		dy <<= 1;
		while (y != y2) {
			putpixel(x, y);
			if (balance >= 0) {
				x += incX;
				balance -= dy;
			}
			balance += dx;
			y += incY;
		}
		putpixel(x, y);
	}
}


void putpixel(int16_t x, int16_t y) {
	uint32_t  pixelRAM;
	byte      block;

	// We only map 8k of the bitmap into CPU RAM at once.
	// We use slot 5 for this.  We need to figure out
	// where our pixel lands and bring that into RAM.
	pixelRAM = _BITMAP_BASE + ((int32_t)y * (int32_t)_MAX_X) + (int32_t)x;
	block = pixelRAM / 0x2000;
	pixelRAM &= 0x1FFF;  // Find offset into this block.
	POKE(MMU_MEM_BANK_5, block);
	POKE(0xa000 + pixelRAM, _color);
	POKE(MMU_MEM_BANK_5, 5);
}


void resetGraphics(void) {
	byte mmu = PEEK(MMU_IO_CTRL);  // Get current MMU state.
	int  x;

	_MAX_X       = 320;
	_MAX_Y       = 240;
	_BITMAP_BASE = 0x10000;

	POKE(MMU_IO_CTRL, MMU_IO_PAGE_0);  // Swap I/O page 0 into bank 6.

	POKE(VKY_LAYER_CTRL_0, 16);  // Bitmaps on all layers.
	POKE(VKY_LAYER_CTRL_1, 1);   // Bitmaps on all layers.
	POKE(VKY_BM1_CTRL, 0);  // Disable bitmap 1.
	POKE(VKY_BM2_CTRL, 0);  // Disable bitmap 2.

	// Set up bitmap 0.
	POKE(VKY_BM0_CTRL, 1);  // Enable bitmap 0, GLUT 0.
	POKEA(VKY_BM0_ADDR_L, _BITMAP_BASE);  // Location of bitmap data.
	//POKE(VKY_BM0_ADDR_L, _BITMAP_BASE & 0xFF);  // Location of bitmap data.
	//POKE(VKY_BM0_ADDR_M, (_BITMAP_BASE >> 8) & 0xFF);  // Location of bitmap data.
	//POKE(VKY_BM0_ADDR_H, (_BITMAP_BASE >> 16) & 0xFF);  // Location of bitmap data.

	POKE(MMU_IO_CTRL, mmu);  // Restore MMU state.

	// Set palette to a gradient so there's at least *something*.
	for (x=0; x<256; x++) defineGraphicsColor(x, x, x, x);

	_color = 0;
	clearBitmap();
	_color = 255;
}


void setGraphicsColor(byte c) {
	_color = c;
}