#include <ft2build.h></ft2build.h>

#include FT_FREETYPE_H

#include "private.h"

#include "font.h"

#include "drawing.h"

#define FONT_MAP_GLYPHSIZE      64

#define FONT_MAP_BORDERSIZE     16

#define FONT_MAP_CNT            16

#define FONT_MAP_GLYPHWORKSIZE  (FONT_MAP_GLYPHSIZE - FONT_MAP_BORDERSIZE)

#define FONT_MAP_FULLCNT        (FONT_MAP_CNT*FONT_MAP_CNT)

#define FONT_MAP_TEXSIZE        (FONT_MAP_CNT*FONT_MAP_GLYPHSIZE)

#define FONT_MAX_GLYPHS         (256*256)

#define FONT_BASE_SIZE          72

#define FONT_BADCHAR_CODE       0xFFFD

typedef struct _HeliFontMap HeliFontMap;

typedef struct _HeliFontInstance HeliFontInstance;

typedef struct _HeliCharDesc HeliCharDesc;

typedef struct _HeliGlyph {

	HeliFontMap *map;

	HeliFontInstance *fi;

	int code;

	int index;

	double l, t, r, b;

	double advance;

} HeliGlyph;

struct _HeliFontMap {

	HeliFontMap *prev, *next;

	unsigned int texid;

	int count;

	HeliGlyph glyphs[FONT_MAP_FULLCNT];

};

struct _HeliFontInstance {

	char *path;

	FT_Face face;

	double height;

	HeliGlyph *glyphs[FONT_MAX_GLYPHS];

	int refcount;

};

struct _HeliCharDesc {

	HeliGlyph *glyph;

	double pos;

	double x, y;

	HeliCharDesc *next;

};

typedef struct _HeliLineDesc {

	int begin, end;

	double x, y;

	double l, t, r, b;

	double height;

} HeliLineDesc;

struct _Font {

	HeliFontInstance *instance;

};

static int ftInitialized = 0;

static FT_Library ftLibrary = NULL;

static HeliArray fontCache;

static HeliFontMap *fontMapFirst, *fontMapLast;

static HeliGlyph blankGlyph;

static const char blankPath[] = "";

static Font defaultFont = NULL;

static HeliFontMap* createFontMap() {

	HeliFontMap *map = calloc(1, sizeof(*map));

	map->prev = fontMapLast;

	*(fontMapLast ? &fontMapLast->next : &fontMapFirst) = map;

	fontMapLast = map;

	for(int i = 0; i < FONT_MAP_FULLCNT; ++i)

		map->glyphs[i].map = map;

	glGenTextures(1, &map->texid);

	glBindTexture(GL_TEXTURE_2D, map->texid);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);

	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_LOD_BIAS, -0.7f);

	char *buffer = calloc(1, FONT_MAP_TEXSIZE*FONT_MAP_TEXSIZE);

	int level = 0;

	for(int size = FONT_MAP_TEXSIZE, border = FONT_MAP_BORDERSIZE; border > 0; border >>= 1, size >>= 1, ++level)

		glTexImage2D(GL_TEXTURE_2D, level, GL_ALPHA, size, size, 0, GL_ALPHA, GL_UNSIGNED_BYTE, buffer);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, level - 1);

	free(buffer);

	glBindTexture(GL_TEXTURE_2D, 0);

	return map;

}

static void destroyFontMap(HeliFontMap *map) {

	assert(!map->count);

	glDeleteTextures(1, &map->texid);

	*(map->prev ? &map->prev->next : &fontMapFirst) = map->next;

	*(map->next ? &map->next->prev : &fontMapLast ) = map->prev;

	free(map);

}

static HeliGlyph* loadGlyph(HeliFontInstance *fi, int code) {

	int index = FT_Get_Char_Index(fi->face, (unsigned int)code);

	if (!index) return &blankGlyph;

	if (FT_Load_Glyph(fi->face, index, FT_LOAD_NO_HINTING))

		return &blankGlyph;

	HeliFontMap *map;

	for(map = fontMapFirst; map; map = map->next)

		if (map->count < FONT_MAP_FULLCNT) break;

	if (!map) map = createFontMap();

	HeliGlyph *g = NULL;

	for(int i = 0; i < FONT_MAP_FULLCNT; ++i)

		if (!map->glyphs[i].fi) { g = &map->glyphs[i]; break; }

	assert(g);

	const double ftkf = 1/64.0;

	const FT_Glyph_Metrics *metrics = &fi->face->glyph->metrics;

	g->l = metrics->horiBearingX*ftkf;

	g->r = (metrics->horiBearingX + metrics->width)*ftkf;

	g->t = -metrics->horiBearingY*ftkf;

	g->b = (-metrics->horiBearingY + metrics->height)*ftkf;

	g->advance = metrics->horiAdvance*ftkf;

	unsigned char buffer[FONT_MAP_GLYPHSIZE * FONT_MAP_GLYPHSIZE] = {};

	if (metrics->width > 0 && metrics->height > 0) {

		FT_Matrix matrix = {};

		matrix.xx = (FONT_MAP_GLYPHWORKSIZE-2)*64*65536/metrics->width;

		matrix.yy = (FONT_MAP_GLYPHWORKSIZE-2)*64*65536/metrics->height;

		FT_Vector offset = {};

		offset.x = 64 - metrics->horiBearingX;

		offset.y = -(64 + metrics->horiBearingY - metrics->height);

		FT_Set_Transform(fi->face, &matrix, &offset);

		int success = !FT_Load_Glyph(fi->face, index, FT_LOAD_NO_HINTING)

				&& !FT_Render_Glyph(fi->face->glyph, FT_RENDER_MODE_NORMAL);

		FT_Set_Transform(fi->face, NULL, NULL);

		if (!success) return &blankGlyph;

		const FT_Bitmap *bitmap = &fi->face->glyph->bitmap;

		int dr = 0;//fi->face->glyph->bitmap_top + 1 - FONT_MAP_GLYPHWORKSIZE;

		int dc = 0;//-fi->face->glyph->bitmap_left;

		int r0 = -dr;

		int r1 = r0 + bitmap->rows;

		int c0 = -dc;

		int c1 = c0 + bitmap->width;

		if (r0 < 0) r0 = 0;

		if (c0 < 0) c0 = 0;

		if (r1 > FONT_MAP_GLYPHWORKSIZE) r1 = FONT_MAP_GLYPHWORKSIZE;

		if (c1 > FONT_MAP_GLYPHWORKSIZE) c1 = FONT_MAP_GLYPHWORKSIZE;

		for(int r = r0; r < r1; ++r)

			for(int c = c0; c < c1; ++c)

				buffer[r*FONT_MAP_GLYPHSIZE + c] = *(bitmap->buffer + bitmap->pitch*(r + dr) + c + dc);

	}

	glBindTexture(GL_TEXTURE_2D, g->map->texid);

	int gi = g - g->map->glyphs;

	int r = gi/FONT_MAP_CNT;

	int c = gi%FONT_MAP_CNT;

	int size = FONT_MAP_GLYPHSIZE;

	for(int level = 0, border = FONT_MAP_BORDERSIZE; border > 0; border >>= 1, ++level) {

		glTexSubImage2D(

			GL_TEXTURE_2D,

			level,

			c*size,

			r*size,

			size,

			size,

			GL_ALPHA,

			GL_UNSIGNED_BYTE,

			buffer );

		if (border > 1) {

			size >>= 1;

			for(int r = 0; r < size; ++r)

				for(int c = 0; c < size; ++c)

					buffer[r*size + c] = (unsigned char)((

					    (unsigned int)buffer[((r*2 + 0)*size + c)*2 + 0]

					  + (unsigned int)buffer[((r*2 + 0)*size + c)*2 + 1]

					  + (unsigned int)buffer[((r*2 + 1)*size + c)*2 + 0]

					  + (unsigned int)buffer[((r*2 + 1)*size + c)*2 + 1] + 2) >> 2 );

		}

	}

	glBindTexture(GL_TEXTURE_2D, 0);

	g->fi = fi;

	g->code = code;

	g->index = index;

	++g->map->count;

	return g;

}

static void unloadGlyph(HeliGlyph *g) {

	g->fi = NULL;

	g->code = 0;

	g->index = 0;

	if (g->map && --g->map->count <= 0) 

		destroyFontMap(g->map);

}

static HeliFontInstance* loadFont(const char *path) {

	HeliFontInstance *fi = calloc(1, sizeof(*fi));

	fi->path = heliStringCopy(path);

	if (!ftInitialized) {

		if (FT_Init_FreeType(&ftLibrary))

			fprintf(stderr, "helianthus: cannot initialize FreeType library\n");

		ftInitialized = TRUE;

	}

	if (ftLibrary) {

		if (path[0]) {

			if (FT_New_Face(ftLibrary, path, 0, &fi->face)) {

				fprintf(stderr, "helianthus: cannot load font from file: %s\n", path);

				fi->face = NULL;

			}

		} else {

			FT_Open_Args args = {};

			args.flags = FT_OPEN_MEMORY;

			args.memory_base = (FT_Byte*)heliBlobDefaultFont;

			args.memory_size = heliBlobDefaultFontSize;

			if (FT_Open_Face(ftLibrary, &args, 0, &fi->face)) {

				fprintf(stderr, "helianthus: cannot initialize default font\n");

				fi->face = NULL;

			}

		}

		if (fi->face) {

			FT_Set_Char_Size(fi->face, 0, FONT_BASE_SIZE*64, 72, 72);

			fi->height = fi->face->size->metrics.height/64.0;

		}

	}

	return fi;

}

static void unloadFont(HeliFontInstance *fi) {

	assert(!fi->refcount);

	for(int i = 0; i < FONT_MAX_GLYPHS; ++i)

		if (fi->glyphs[i]) unloadGlyph(fi->glyphs[i]);

	free(fi->path);

	if (fi->face) FT_Done_Face(fi->face);

	free(fi);

}

static HeliGlyph* getGlyph(HeliFontInstance *fi, int code) {

	if (code < 0 || code >= FONT_MAX_GLYPHS) return &blankGlyph;

	if (!fi->glyphs[code]) fi->glyphs[code] = loadGlyph(fi, code);

	return fi->glyphs[code];

}

Font createFont(const char *path) {

	if (!heliInitialized) return NULL;

	if (!path) path = blankPath;

	Font f = calloc(1, sizeof(*f));

	f->instance = (HeliFontInstance*)heliStringmapGet(&fontCache, path);

	if (!f->instance) {

		f->instance = loadFont(path);

		heliStringmapAdd(&fontCache, path, f->instance, (HeliFreeCallback)&unloadFont);

	}

	++f->instance->refcount;

	heliObjectRegister(f, (HeliFreeCallback)&fontDestroy);

	return f;

}

void fontDestroy(Font f) {

	heliObjectUnregister(f);

	HeliDrawingState *ss = heliDrawingGetState();

	for(HeliDrawingState *s = heliDrawingGetStateStack(); s <= ss; ++s)

		{ if (ss->font == f) ss->font = NULL; }

	--f->instance->refcount;

	if (f->instance->refcount <= 0)

		heliStringmapRemove(&fontCache, f->instance->path);

	free(f);

}

void textAlign(HAlign hor, VAlign vert) {

	HeliDrawingState *s = heliDrawingGetState();

	s->horAlign = hor;

	s->vertAlign = vert;

}

void textFontDefault()

	{ heliDrawingGetState()->font = NULL; }

void textFont(Font f)

	{ heliDrawingGetState()->font = f; }

void textSize(double size)

	{ heliDrawingGetState()->fontSize = size; }

void text(const char *text, double x, double y) {

	resetPath();

	HeliDrawingState *drawingState = heliDrawingGetState();

	double fontScale = drawingState->fontSize/FONT_BASE_SIZE;

	if (fontScale < HELI_PRECISION) return;

	if (drawingState->colorStroke[3] < HELI_PRECISION) return;

	if (!defaultFont) defaultFont = createFont(NULL);

	HeliFontInstance *f = drawingState->font ? drawingState->font->instance : NULL;

	HeliFontInstance *ff = defaultFont ? defaultFont->instance : NULL;

	if (!f) f = ff;

	if (!ff) ff = f;

	if (!f) return;

	if (!f->face) f = ff;

	if (!ff->face) ff = f;

	if (!f->face) return;

	int linesCount = 1;

	int linesAllocated = 256;

	HeliLineDesc *lines = calloc(linesAllocated, sizeof(HeliLineDesc));

	HeliLineDesc *line = lines;

	line->height = f->height;

	HeliCharDesc *chars = calloc(strlen(text), sizeof(HeliCharDesc));

	// gather glyphs

	const char *c = text;

	while(1) {

		int code = FONT_BADCHAR_CODE;

		while((*c & 0xC0) == 0x80) ++c;

		if ((*c & 0x80) == 0x00) {

			code = *c;

		} else

		if ((*c & 0xE0) == 0xC0) {

			if ((c[1] & 0xC0) == 0x80) {

				code = ((c[0] & 0x1F) << 6) | (c[1] & 0x3F);

				c += 1;

			}

		} else

		if ((*c & 0xF0) == 0xE0) {

			if ((c[1] & 0xC0) == 0x80 && (c[2] & 0xC0) == 0x80) {

				code = ((c[0] & 0x0F) << 12) | ((c[1] & 0x3F) << 6) | (c[2] & 0x3F);

				c += 2;

			}

		}

		++c;

		if (code == 0) break;

		if (code == 10 || code == 13) {

			if ((code == 10 && *c == 13) || (code == 13 && *c == 10)) ++c;

			if (linesCount >= linesAllocated) {

				linesAllocated += linesAllocated/4;

				lines = realloc(lines, linesAllocated*sizeof(HeliLineDesc));

				memset(lines + linesCount, 0, (linesAllocated - linesCount)*sizeof(HeliLineDesc));

				line = &lines[linesCount - 1];

			}

			++line;

			++linesCount;

			line->begin = line->end = (line - 1)->end;

			line->height = f->height;

			continue;

		}

		HeliGlyph *glyph = &blankGlyph;

		if (!glyph->fi) glyph = getGlyph(f, code);

		if (!glyph->fi) glyph = getGlyph(ff, code);

		if (!glyph->fi) glyph = getGlyph(f, FONT_BADCHAR_CODE);

		if (!glyph->fi) glyph = getGlyph(ff, FONT_BADCHAR_CODE);

		if (!glyph->fi) continue;

		HeliCharDesc *cc = &chars[line->end++];

		cc->glyph = glyph;

		if (line->height < glyph->fi->height) line->height = glyph->fi->height;

		if (line->end - 1 <= line->begin) {

			line->l = cc->glyph->l;

			line->t = cc->glyph->t;

			line->r = cc->glyph->r;

			line->b = cc->glyph->b;

		} else {

			HeliCharDesc *cp = cc - 1;

			cc->pos = cp->pos + cp->glyph->advance;

			FT_Vector kerning = {};

			if ( cp->glyph->fi == cc->glyph->fi 

			  && !FT_Get_Kerning(

					cc->glyph->fi->face,

					cp->glyph->index,

					cc->glyph->index,

					FT_KERNING_UNFITTED,

					&kerning ))

				cc->pos += kerning.x/64.0;

			if (line->l > cc->glyph->l + cc->pos) line->l = cc->glyph->l + cc->pos;

			if (line->r < cc->glyph->r + cc->pos) line->r = cc->glyph->r + cc->pos;

			if (line->t > cc->glyph->t) line->t = cc->glyph->t;

			if (line->b < cc->glyph->b) line->b = cc->glyph->b;

		}

	}

	// bounds

	double l = lines->l;

	double t = lines->t;

	double r = lines->r;

	double b = lines->b;

	for(int i = 1; i < linesCount; ++i) {

		HeliLineDesc *line = &lines[i];

		line->y = (line-1)->y + line->height;

		if (l > line->l) l = line->l;

		if (r < line->r) r = line->r;

		if (t > line->t + line->y) t = line->t + line->y;

		if (b < line->b + line->y) b = line->b + line->y;

	}

	// alignment

	double dy = drawingState->vertAlign == VALIGN_BOTTOM ? -b

	          : drawingState->vertAlign == VALIGN_CENTER ? -0.5*(t + b)

	          :                                            -t;

	for(int i = 0; i < linesCount; ++i) {

		HeliLineDesc *line = &lines[i];

		line->x = drawingState->horAlign == HALIGN_RIGHT  ? -line->r

		        : drawingState->horAlign == HALIGN_CENTER ? -0.5*(line->l + line->r)

		        :                                           -line->l;

		line->y += dy;

		for(int j = line->begin; j < line->end; ++j) {

			HeliCharDesc *cc = &chars[j];

			cc->x = cc->pos + line->x;

			cc->y = line->y;

		}

	}

	// sort by textures	

	int charsCount = lines[linesCount-1].end;

	for(int i = 0; i < charsCount-1; ++i)

		chars[i].next = &chars[i+1];

	HeliCharDesc *first = NULL, *last = NULL, *current = chars;

	while(current) {

		if (!current->next) {

			current = current->next = first;

		} else

		if (current->glyph->map != current->next->glyph->map) {

			*(last ? &last->next : &first) = current->next;

			last = current->next;

			current->next = current->next->next;

			last->next = NULL;

		} else {

			current = current->next;

		}

	}

	// draw

	const double borderK = 0.5*FONT_MAP_BORDERSIZE/FONT_MAP_GLYPHWORKSIZE;

	const double texStep = 1.0/FONT_MAP_CNT;

	const double texOffset = -0.5*FONT_MAP_BORDERSIZE/FONT_MAP_TEXSIZE;

	glPushMatrix();

	glTranslated(x, y, 0);

	glScaled(fontScale, fontScale, 1);

	glColor4dv(drawingState->colorStroke);

	HeliFontMap *currentMap = NULL;

	glEnable(GL_TEXTURE_2D);

	glBegin(GL_QUADS);

	for(HeliCharDesc *cc = chars; cc; cc = cc->next) {

		if ( !cc->glyph->map

		  || cc->glyph->r - cc->glyph->l <= HELI_PRECISION

		  || cc->glyph->b - cc->glyph->t <= HELI_PRECISION )

			continue;

		if (currentMap != cc->glyph->map) {

			glEnd();

			currentMap = cc->glyph->map;

			glBindTexture(GL_TEXTURE_2D, currentMap->texid);

			glBegin(GL_QUADS);

		}

		double dx = (cc->glyph->r - cc->glyph->l)*borderK;

		double dy = (cc->glyph->b - cc->glyph->t)*borderK;

		double l = cc->x + cc->glyph->l - dx;

		double t = cc->y + cc->glyph->t - dy;

		double r = cc->x + cc->glyph->r + dx;

		double b = cc->y + cc->glyph->b + dy;

		int gi = cc->glyph - cc->glyph->map->glyphs;

		double tl = (gi % FONT_MAP_CNT)*texStep + texOffset;

		double tt = (gi / FONT_MAP_CNT)*texStep + texOffset;

		double tr = tl + texStep;

		double tb = tt + texStep;

		glTexCoord2d(tl, tt); glVertex2d(l, t);

		glTexCoord2d(tr, tt); glVertex2d(r, t);

		glTexCoord2d(tr, tb); glVertex2d(r, b);

		glTexCoord2d(tl, tb); glVertex2d(l, b);

	}

	glEnd();

	glBindTexture(GL_TEXTURE_2D, 0);

	glDisable(GL_TEXTURE_2D);

	glPopMatrix();

	glColor4d(1, 1, 1, 1);

}

void heliFontFinish() {

	heliArrayDestroy(&fontCache);

	if (ftInitialized && ftLibrary) FT_Done_FreeType(ftLibrary);

	ftLibrary = NULL;

	ftInitialized = FALSE;

}