#include "text.h"
#include "shader.h"
#include "sys.h"
#include <GL/glew.h>
#include <ft2build.h>
#include FT_FREETYPE_H

struct text_renderer init_text_renderer(i32 width, i32 height)
{
	struct text_renderer renderer = {0};
	renderer.shader = get_shader("text");
	glUseProgram(renderer.shader);
	mat projection = ortho(0.0f, width, height, 0.0f, -1.0f, 1.0f);
	uniform_mat(renderer.shader, "projection", projection);
	uniform_i32(renderer.shader, "glyph", 0);
	glUseProgram(0);
	glGenVertexArrays(1, &renderer.vao);
	glGenBuffers(1, &renderer.vbo);
	glBindVertexArray(renderer.vao);
	glBindBuffer(GL_ARRAY_BUFFER, renderer.vbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(f32) * 6 * 4, 0, GL_DYNAMIC_DRAW);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(f32), 0);
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	glBindVertexArray(0);
	return renderer;
}

void load_font(struct text_renderer *renderer, const char *dir, const char *filename, u32 size)
{
	for (i32 i = 0; i < 128; i++) {
		struct text_char *c = renderer->chars + i;
		c->texture = 0;
		c->size = (v2){0.0f, 0.0f};
		c->bearing = (v2){0.0f, 0.0f};
		c->advance = 0;
	}
	FT_Library ft;
	if (FT_Init_FreeType(&ft))
		die("failed to initialize freetype library");
	FT_Face face;
	char path[512] = {0};
	snprintf(path, 512, "%s/%s", (dir ? dir : "."), filename);
	if (FT_New_Face(ft, path, 0, &face))
		die("failed to load \"%s\"", path);
	FT_Set_Pixel_Sizes(face, 0, size);
	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
	for (u8 c = 0; c < 128; c++) {
		if (FT_Load_Char(face, c, FT_LOAD_RENDER))
			die("failed to load char \"%c\"", c);
		u32 texture;
		glGenTextures(1, &texture);
		glBindTexture(GL_TEXTURE_2D, texture);
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RED,
			     face->glyph->bitmap.width,
			     face->glyph->bitmap.rows,
			     0, GL_RED, GL_UNSIGNED_BYTE,
			     face->glyph->bitmap.buffer);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
		renderer->chars[c] = (struct text_char){
			texture,
		       	{face->glyph->bitmap.width, face->glyph->bitmap.rows},
		       	{face->glyph->bitmap_left, face->glyph->bitmap_top},
		       	face->glyph->advance.x
		};
		glBindTexture(GL_TEXTURE_2D, 0);
	}
	FT_Done_Face(face);
	FT_Done_FreeType(ft);
	info("font \"%s\" loaded successfully", path);
}

v2 get_text_size(struct text_renderer renderer, const char *text, f32 scale)
{
	v2 size = {0};
	for (const char *c = text; *c; c++) {
		struct text_char ch = renderer.chars[(u8)*c];
		f32 h = ch.size.y * scale;
		if (h > size.y)
			size.y = h;
		size.x += (ch.advance >> 6) * scale;
	}
	return size;
}

void render_text(struct text_renderer renderer, const char *text, v2 pos, f32 scale, v3 color)
{
	glUseProgram(renderer.shader);
	uniform_v3(renderer.shader, "text_color", color);
	glActiveTexture(GL_TEXTURE0);
	glBindVertexArray(renderer.vao);
	for (const char *c = text; *c; c++) {
		struct text_char ch = renderer.chars[(u8)*c];
		f32 x = pos.x + ch.bearing.x * scale;
		f32 y = pos.y + (renderer.chars['H'].bearing.y - ch.bearing.y) * scale;
		f32 w = ch.size.x * scale;
		f32 h = ch.size.y * scale;
		f32 vertices[] = {
			x,     y + h, 0.0f, 1.0f,
			x + w, y,     1.0f, 0.0f,
			x,     y,     0.0f, 0.0f,

			x,     y + h, 0.0f, 1.0f,
			x + w, y + h, 1.0f, 1.0f,
			x + w, y,     1.0f, 0.0f,
		};
		glBindTexture(GL_TEXTURE_2D, ch.texture);
		glBindBuffer(GL_ARRAY_BUFFER, renderer.vbo);
		glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertices), vertices);
		glBindBuffer(GL_ARRAY_BUFFER, 0);
		glDrawArrays(GL_TRIANGLES, 0, 6);
		glBindTexture(GL_TEXTURE_2D, 0);
		pos.x += (ch.advance >> 6) * scale;
	}
	glBindVertexArray(0);
	glUseProgram(0);
}

void render_text_centered(struct text_renderer renderer, const char *text, v2 pos, f32 scale, v3 color)
{
	v2 size = get_text_size(renderer, text, scale);
	v2 top_left = sub_v2(pos, scale_v2(size, 0.5f));
	render_text(renderer, text, top_left, scale, color);
}