#include"k3font.h"

#include"k3batch.h"
#include<string.h>
#include"gl.h"

struct k3Font *k3FontCreate() {
	struct k3Font *ret = calloc(sizeof(*ret), 1);
	return ret;
}

static int cmpglyph(const void *a, const void *b) {
	return *(const uint32_t*) a - *(const uint32_t*) b;
}

int k3FontLoad(struct k3Font *this, const uint8_t *buf, size_t len, k3FontTexLoader texldr) {
	if(*(uint32_t*) buf != 0x03464D42) {
		return 0;
	}
	
	const uint8_t *end = buf + len;
	
	buf += 4;
	
	uint16_t pages = 0;
	
	while(buf + 5 < end) {
		uint8_t blockType = *buf;
		uint32_t blockSize = *(uint32_t*) (buf + 1);
		buf += 5;
		
		if(blockType == 1) { //Info block
			buf += 14;
			while(*buf) buf++;
			buf++;
		} else if(blockType == 2) { //Common block
			this->lineScale = 1.f / *(uint16_t*) buf;
			buf += 2;
			this->baseline = *(uint16_t*) buf;
			buf += 2;
			this->texW = *(uint16_t*) buf;
			buf += 2;
			this->texH = *(uint16_t*) buf;
			buf += 2;
			pages = *(uint16_t*) buf;
			buf += 7;
		} else if(blockType == 3) { //Pages block
			if(pages == 0) return 0;
			
			this->pageCount = pages;
			this->pages = malloc(sizeof(*this->pages) * this->pageCount);
			
			for(size_t i = 0; i < this->pageCount; i++) {
				this->pages[i] = texldr(this, buf);
				buf += strlen(buf) + 1;
			}
		} else if(blockType == 4) { //Chars block
			size_t num = blockSize / 20;
			
			this->glyphs = calloc(sizeof(*this->glyphs), this->glyphCount = num);
			
			memcpy(this->glyphs, buf, num * 20);
			
			qsort(this->glyphs, num, sizeof(*this->glyphs), cmpglyph);
			
			buf += blockSize;
		} else if(blockType == 5) { //Kerning block
			// Ignore kerning for now
			buf += blockSize;
		}
	}
	
	return 1;
}

static uint32_t read_utf8(const char **txt_) {
	const uint8_t **txt = (void*) txt_;
	if(**txt == 0) {
		return 0;
	} else if(**txt < 0x80) {
		return *(*txt)++;
	} else if(**txt < 0xE0) {
		uint32_t ret = ((*(*txt)++) & 0x1F) << 6;
		ret |= (*(*txt)++) & 0x3F;
		return ret;
	} else if(**txt < 0xF0) {
		uint32_t ret = ((*(*txt)++) & 0x0F) << 12;
		ret |= ((*(*txt)++) & 0x3F) << 6;
		ret |= (*(*txt)++) & 0x3F;
		return ret;
	} else {
		uint32_t ret = ((*(*txt)++) & 0x07) << 18;
		ret |= ((*(*txt)++) & 0x3F) << 12;
		ret |= ((*(*txt)++) & 0x3F) << 6;
		ret |= (*(*txt)++) & 0x3F;
		return ret;
	}
}

void k3FontSz(struct k3Font *this, float sz, const char *txt, float wall, struct k3RectF *ret) {
	if(wall < 0) {
		wall = HUGE_VALF;
	}
	
	float maxX = 0;
	
	float x = 0, y = sz;
	while(1) {
		uint32_t cp = read_utf8(&txt);
		
		if(!cp) break;
		
		if(cp == 10) {
			x = 0;
			y += sz;
		}
		
		struct k3FontGlyph *g = k3FontGetGlyph(this, cp);
		
		if(!g) continue;
		
		if(x + g->width > wall) {
			x = 0;
			y += sz;
		}
		
		x += g->xadvance * this->lineScale * sz;
		maxX = fmaxf(maxX, x);
	}
	
	ret->w = maxX;
	ret->h = y;
}
void k3FontDraw(struct k3Font *this, float xStart, float yStart, float sz, const char *txt, float wall, vec4 color) {
	if(wall < 0) {
		wall = HUGE_VALF;
	}
	
	float x = xStart, y = yStart;
	while(1) {
		uint32_t cp = read_utf8(&txt);
		
		if(!cp) break;
		
		if(cp == 10) {
			x = xStart;
			y -= sz;
		}
		
		struct k3FontGlyph *g = k3FontGetGlyph(this, cp);
		
		if(!g) continue;
		
		if(x + g->width - xStart > wall) {
			x = xStart;
			y -= sz;
		}
		
		struct k3Tex *tex = this->pages[g->page];
		size_t texW = this->texW;
		size_t texH = this->texH;
		
		k3BatchAdd(tex,
			(struct k3RectF) {(float) g->x / texW, (float) g->y / texH, (float) g->width / texW, (float) g->height / texH},
			(struct k3RectF) {
				x + g->xoffset * this->lineScale * sz,
				y + ((-g->height - g->yoffset) * this->lineScale + 1) * sz,
				g->width * this->lineScale * sz,
				g->height * this->lineScale * sz
			}, 0, color, 0);
		
		x += g->xadvance * this->lineScale * sz;
	}
	k3BatchFlush();
}

struct k3FontGlyph *k3FontGetGlyph(struct k3Font *this, uint32_t cp) {
	return bsearch(&cp, this->glyphs, this->glyphCount, sizeof(*this->glyphs), cmpglyph);
}