#include "maths.h"
#include "plat.h"
#include "render.h"
#include <stdlib.h>

static int font_w = 960;
static unsigned font_data[] = {
	0x00000000, 0x00003000, 0x00000000, 0x00000000, 0x00000000,
	0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
	0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
	0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
	0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
	0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
	0x0cc0c000, 0x8000301b, 0x60601803, 0x00000000, 0x20000000,
	0x0780c078, 0x83f0e01e, 0xe0783f07, 0x60000001, 0x1e018000,
	0x07e0c078, 0xe3f87e1f, 0xe0cc1e0f, 0x1e638f01, 0x1f0c6318,
	0x07e1f07e, 0xc330fc1e, 0x30cc318c, 0x021e0fc3, 0x000101e0,
	0x00e00000, 0x0000e000, 0xc00e0007, 0x3c038c00, 0x00000000,
	0x00000000, 0x00001000, 0x00000000, 0x30380000, 0x0000c070,
	0x0cc1e000, 0xc630f81b, 0xc0301806, 0x00000cc0, 0x30000000,
	0x0cc0f0cc, 0xc030f033, 0x30cc330c, 0x30000003, 0x33030000,
	0x8cc1e0cc, 0xc230cc33, 0xc0cc3308, 0x0c630600, 0x318ce3b8,
	0x0cc318cc, 0xc330b433, 0x30cc318c, 0x06060cc3, 0x00038180,
	0x00c00018, 0x8000c000, 0x000c000d, 0x30030000, 0x00000000,
	0x00000000, 0x00001800, 0x00000000, 0x300c0000, 0x0409e0c0,
	0x8481e000, 0xc3300c3f, 0x80180c06, 0x000c0781, 0x18000000,
	0x0c00c0ec, 0xc1f0d830, 0x30cc1800, 0x180c0303, 0x30060000,
	0x8cc330ec, 0xc0318c01, 0xc0cc3180, 0x0c330600, 0x318de3f8,
	0x0cc318cc, 0xc3303003, 0x3078318c, 0x0c060643, 0x0006c180,
	0x07c0f018, 0x81e0f81e, 0xf06c3701, 0x30330f00, 0x1e07c1f8,
	0x0ee37076, 0xc330fc3e, 0x30c6318c, 0x300c0fc3, 0x0e0f20c0,
	0x0001e000, 0x8180781b, 0x80180013, 0x000c1fe1, 0x0c000000,
	0x0600c0dc, 0xc300cc1c, 0xe0780c07, 0x0c0c0303, 0x180c03f0,
	0x87c330ec, 0xc1f18c01, 0xc0fc0187, 0x0c1f0600, 0x318fe358,
	0x07c3187c, 0xc330300e, 0xe030358c, 0x18060301, 0x000c6180,
	0x0cc18030, 0xc330cc33, 0xc0dc1987, 0x301b0c00, 0x330cc358,
	0x0dc198cc, 0xc3301803, 0x306c358c, 0x00060643, 0x1b060180,
	0x0000c000, 0xc0c0c01b, 0x8018001e, 0x003f0781, 0x060003f0,
	0x0300c0cc, 0xc301fc30, 0x00cc0c0c, 0x0c000003, 0x0c0c0000,
	0x8cc3f00c, 0xc0318c01, 0xc0cc3980, 0x0c330660, 0x318f6318,
	0x06c3980c, 0xc3303018, 0xc078358c, 0x30060180, 0x00000180,
	0x0cc1f000, 0x83f0cc03, 0xc0cc1981, 0x301f0c00, 0x330cc358,
	0x00c198cc, 0xc330181e, 0x3038358c, 0x300c0303, 0x318000c0,
	0x80000000, 0xc6607c3f, 0xc030000c, 0x300c0cc0, 0x03030000,
	0x0180c0cc, 0xc330c033, 0x30cc0c0c, 0x180c0303, 0x000603f0,
	0x8cc3308c, 0xc230cc33, 0xc0cc3300, 0x8c630660, 0x318e6318,
	0x0cc1f00c, 0x83303033, 0xc0cc1f07, 0x600609c0, 0x00000180,
	0x0cc19800, 0x8030cc33, 0xc0cc1f01, 0x30330cc0, 0x330cc358,
	0x00c198cc, 0x8330d830, 0xe06c1f07, 0x300c0981, 0x318000c0,
	0x0000c000, 0x8630301b, 0x6060001b, 0x300c0000, 0x01830000,
	0x0fc3f078, 0x81e0c01e, 0xe0780c07, 0x300c0301, 0x0c030000,
	0x07e33078, 0xe3f87e1f, 0xe0cc3e01, 0xfe6383c1, 0x1f0c6318,
	0x0ce3c01e, 0x01e0781e, 0xe0cc1b03, 0xc01e0fc1, 0x000001e0,
	0x07e3f000, 0xc1e0f81e, 0xf0ce1803, 0xfc338783, 0x1e0cc318,
	0x01e1f07c, 0x06e0701f, 0x80c61b03, 0x30380fc1, 0x3f800070,
	0x0000c000, 0x0000301b, 0x00000000, 0x18000000, 0x00800000,
	0x00000000, 0x00000000, 0x00000000, 0x60060000, 0x00018000,
	0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
	0x00000000, 0x00000000, 0x00000000, 0x80000000, 0x7f800000,
	0x00000000, 0x00000000, 0x00000f00, 0x00000000, 0x00000000,
	0x0001800c, 0x00000000, 0xf0000000, 0x00000000, 0x00000000,
	0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
	0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
	0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
	0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
	0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
	0x0003c01e, 0x00000000, 0x00000000, 0x00000000, 0x00000000
};

Colour make_colour(unsigned rgb, unsigned char a) {
	Colour r;
	r.r = (unsigned char)(rgb >> 16);
	r.g = (unsigned char)(rgb >> 8);
	r.b = (unsigned char)rgb;
	r.a = a;
	return r;
}

Colour make_red(void) {
	return make_colour(0xff0000, 0xff);
}

Colour make_green(void) {
	return make_colour(0x00ff00, 0xff);
}

Colour make_blue(void) {
	return make_colour(0x0000ff, 0xff);
}

Colour make_cyan(void) {
	return make_colour(0x00ffff, 0xff);
}

Colour make_pink(void) {
	return make_colour(0xff00ff, 0xff);
}

Colour make_yellow(void) {
	return make_colour(0xffff00, 0xff);
}

Colour make_aliceblue(void) {
	return make_colour(0xf0f8ff, 0xff);
}

Colour blend(Colour dst, Colour src) {
	int ima;
	ima = 0xff - src.a;
	dst.r = (unsigned char)(((src.r * src.a) + (dst.r * ima)) >> 8);
	dst.g = (unsigned char)(((src.g * src.a) + (dst.g * ima)) >> 8);
	dst.b = (unsigned char)(((src.b * src.a) + (dst.b * ima)) >> 8);
	return dst;
}

Colour blend_mod(Colour dst, Colour src, Colour mod) {
	int ima;
	src.a = (src.a * mod.a) >> 8;
	ima = 0xff - src.a;
	dst.r = (unsigned char)(((src.r * mod.r * src.a) >> 16) + ((dst.r * ima) >> 8));
	dst.g = (unsigned char)(((src.g * mod.g * src.a) >> 16) + ((dst.g * ima) >> 8));
	dst.b = (unsigned char)(((src.b * mod.b * src.a) >> 16) + ((dst.b * ima) >> 8));
	return dst;
}

Colour col_mul(Colour a, Colour b) {
	Colour r;
	r.r = (a.r * b.r) >> 8;
	r.g = (a.g * b.g) >> 8;
	r.b = (a.b * b.b) >> 8;
	r.a = (a.a * b.a) >> 8;
	return r;
}

void ren_begin(Renderer* r, Colour* t, int* d, int w, int h) {
	r->t = t;
	r->w = w;
	r->h = h;
	r->d = d;
	r->clip.x = 0;
	r->clip.y = 0;
	r->clip.w = w;
	r->clip.h = h;
}

void ren_end(Renderer* r) {
	(void)r;
}

void ren_clear(Renderer* r) {
	Colour* d = r->t, b = { 0 };
	int i = 0, e = r->w * r->h;
	for (i = 0; i < e; i++, d++)
		*d = b;
}

void ren_clearc(Renderer* r, Colour c) {
	Colour* d = r->t;
	int i = 0, e = r->w * r->h;
	for (i = 0; i < e; i++, d++)
		*d = c;
}

void ren_cleard(Renderer* r, int depth) {
	int* d = r->d;
	int i = 0, e = r->w * r->h;
	for (i = 0; i < e; i++, d++)
		*d = depth;
}

void ren_clip(Renderer* r, const Rect* c) {
	r->clip = *c;
}

void ren_point(Renderer* r, Colour c, int x, int y) {
	if (x < 0) return;
	if (y < 0) return;
	if (x >= r->w) return;
	if (y >= r->h) return;
	r->t[x + y * r->w] = c;
}

void ren_char(
	Renderer* r,
	Colour c,
	int x,
	int y,
	char ch
) {
	int i, j, k, l, ex, ey, s;
	Colour* dst;
	Rect re = { 0, 0, 10, 10 };
	Rect sub = { 0, 0, 10, 10 };
	re.x = x;
	re.y = y;
	sub.x = (ch - ' ') * 10;
	rect_clips(&re, &sub, &r->clip);
	ex = re.x + re.w;
	ey = re.y + re.h;
	dst = r->t + (re.x + re.y * r->w);
	s = r->w - re.w;
	for (j = re.y, l = sub.y; j < ey; j++, l++) {
		for (i = re.x, k = sub.x; i < ex; i++, k++) {
			int si = k + l * font_w;
			unsigned bits = font_data[si >> 5];
			int bit = bits & 1 << (si & 0x1f);
			if (bit)
				*dst = blend(*dst, c);
			dst++;
		}
		dst += s;
	}
}

void ren_text(
	Renderer* r,
	Colour c,
	int x,
	int y,
	const char* t
) {
	const char* s;
	for (s = t; *s; s++, x += 10)
		ren_char(r, c, x, y, *s);
}

void swap_vert(int* a, int* b, int ec) {
	int t, i;
	for (i = 0; i < ec; i++) {
		t = a[i];
		a[i] = b[i];
		b[i] = t;
	}
}

int tri_hand(
	const int* v0,
	const int* v1,
	const int* v2
) {
	return
		(v1[0] - v0[0]) * (v2[1] - v0[1]) -
		(v2[0] - v0[0]) * (v1[1] - v0[1]) > 0;
}

Colour sample_tex(
	const Bitmap* t,
	int u,
	int v
) {
	int x = (u * t->w) >> fbits;
	int y = (v * t->h) >> fbits;
	x &= t->w - 1;
	y &= t->h - 1;
	return t->p[x + y * t->w];
}

typedef struct {
	int x, y;
	int dx, dy;
	int sx, sy;
	int e;
} Line;

void init_line(
	Line* l,
	const int* f,
	const int* t
) {
	const int dx =  abs(t[0] - f[0]);
	const int dy = -abs(t[1] - f[1]);
	l->e = dx + dy;
	l->dx = dx;
	l->dy = dy;
	l->sx = f[0] < t[0]? 1: -1;
	l->sy = f[1] < t[1]? 1: -1;
	l->x = f[0];
	l->y = f[1];
}

void init_lerp(
	Line* l,
	int a, int b,
	int x, int y
) {
	int f[2], t[2];
	f[0] = a;
	f[1] = x;
	t[0] = b;
	t[1] = y;
	init_line(l, f, t);
}

void step_line(
	Line* l
) {
	const int e2 = l->e * 2;
	const int dx = l->dx;
	const int dy = l->dy;
	if (e2 > dy) {
		l->e += dy;
		l->x += l->sx;
	}
	if (e2 <= dx) {
		l->e += dx;
		l->y += l->sy;
	}
}

void ren_tri(
	Renderer* r,
	const int* iv0,
	const int* iv1,
	const int* iv2,
	const Bitmap* tex
) {
#define ic 6
#define ec 8
	int ha, i;
	int v0[ec], v1[ec], v2[ec];
	Line ne, fe; /* near and far edges */
	Line ni[ic], fi[ic]; /* near and far interpolants */
	Line xi[ic]; /* scanline interpolant */
	vec_cpy(v0, iv0, ec);
	vec_cpy(v1, iv1, ec);
	vec_cpy(v2, iv2, ec);
	if (v0[1] > v1[1])
		swap_vert(v0, v1, ec);
	if (v1[1] > v2[1])
		swap_vert(v1, v2, ec);
	if (v0[1] > v1[1])
		swap_vert(v0, v1, ec);
	ha = tri_hand(v0, v1, v2);
	if (ha) {
		init_line(&ne, v0, v2);
		init_line(&fe, v0, v1);
		for (i = 0; i < ic; i++) {
			init_lerp(
				&ni[i],
				v0[2 + i], v2[2 + i],
				v0[1],     v2[1]
			);
			init_lerp(
				&fi[i],
				v0[2 + i], v1[2 + i],
				v0[1],     v1[1]
			);
		}
	} else {
		init_line(&ne, v0, v1);
		init_line(&fe, v0, v2);
		for (i = 0; i < ic; i++) {
			init_lerp(
				&ni[i],
				v0[2 + i], v1[2 + i],
				v0[1],     v1[1]
			);
			init_lerp(
				&fi[i],
				v0[2 + i], v2[2 + i],
				v0[1],     v2[1]
			);
		}
	}
#define scanline\
		int x;\
		for (i = 0; i < ic; i++)\
			init_lerp(\
				&xi[i],\
				ni[i].x, fi[i].x,\
				ne.x, fe.x\
			);\
		for (x = ne.x; x < fe.x; x++) {\
			Colour col;\
			col.r = (xi[3].x * 255) >> fbits;\
			col.g = (xi[4].x * 255) >> fbits;\
			col.b = (xi[5].x * 255) >> fbits;\
			col.a = 0xff;\
			if (xi[0].x < r->d[x + fe.y * r->w]) { \
				r->t[x + fe.y * r->w] =	col_mul(\
					sample_tex(tex, xi[1].x, xi[2].x),\
					col\
				);\
				r->d[x + fe.y * r->w] = xi[0].x; \
			} \
			for (i = 0; i < ic; i++)\
				while (xi[i].y != x)\
					step_line(&xi[i]);\
		}\
		step_line(&fe);\
		for (i = 0; i < ic; i++)\
			while (fi[i].y != fe.y)\
				step_line(&fi[i]);\
		while (ne.y != fe.y)\
			step_line(&ne);\
		for (i = 0; i < ic; i++)\
			while (ni[i].y != ne.y)\
				step_line(&ni[i]);
	while (fe.y < v1[1]) {
		scanline
	}
	if (ha) {
		init_line(&fe, v1, v2);
		for (i = 0; i < ic; i++)
			init_lerp(
				&fi[i],
				v1[2 + i], v2[2 + i],
				v1[1],     v2[1]
			);
	} else {
		init_line(&ne, v1, v2);
		for (i = 0; i < ic; i++)
			init_lerp(
				&ni[i],
				v1[2 + i], v2[2 + i],
				v1[1],     v2[1]
			);
	}
	while (fe.y < v2[1]) {
		scanline
	}
#undef scanline
#undef ic
#undef ec
}