#include "../../include/mgl/graphics/text.h"
#include "../../include/mgl/graphics/font.h"
#include "../../include/mgl/system/utf8.h"
#include "../../include/mgl/mgl.h"
#include <stdio.h>

#define TAB_WIDTH 4

static float max_float(float a, float b) {
    return a >= b ? a : b;
}

static mgl_vec2f mgl_text_calculate_bounds(mgl_text *self) {
    mgl_vec2f bounds;
    bounds.x = 0.0f;
    bounds.y = self->font->character_size;

    /* TODO: Combine this with the loop in mgl_text_draw */
    mgl_font_glyph glyph;
    float width = 0.0f;
    for(size_t i = 0; i < self->text_size;) {
        unsigned char *cp = (unsigned char*)&self->text[i];
        uint32_t codepoint;
        size_t clen;
        if(!mgl_utf8_decode(cp, self->text_size - i, &codepoint, &clen)) {
            codepoint = *cp;
            clen = 1;
        }

        if(codepoint == '\t') {
            if(mgl_font_get_glyph(self->font, ' ', &glyph) == 0) {
                width += (glyph.advance * TAB_WIDTH);
                bounds.x = max_float(bounds.x, width);
            }
        } else if(codepoint == '\n') {
            width = 0.0f;
            bounds.y += self->font->character_size;
        } else {
            if(mgl_font_get_glyph(self->font, codepoint, &glyph) == 0) {
                width += glyph.advance;
                bounds.x = max_float(bounds.x, width);
            }
        }
        i += clen;
    }

    return bounds;
}

void mgl_text_init(mgl_text *self, mgl_font *font, const char *str, size_t str_size) {
    self->font = font;
    self->color = (mgl_color){ 255, 255, 255, 255 };
    self->position = (mgl_vec2f){ 0.0f, 0.0f };
    self->text = NULL;
    self->text_size = 0;
    mgl_text_set_string(self, str, str_size);
}

void mgl_text_deinit(mgl_text *self) {
    self->font = NULL;
    self->position = (mgl_vec2f){ 0.0f, 0.0f };
    self->text = NULL;
    self->text_size = 0;
    self->bounds = (mgl_vec2f){ 0.0f, 0.0f };
}

void mgl_text_set_string(mgl_text *self, const char *str, size_t str_size) {
    self->text = str;
    self->text_size = str_size;
    if(self->text && self->text_size > 0 && self->font)
        self->bounds = mgl_text_calculate_bounds(self);
    else
        self->bounds = (mgl_vec2f){ 0.0f, 0.0f };
}

void mgl_text_set_font(mgl_text *self, mgl_font *font) {
    self->font = font;
    if(self->font) {
        if(self->bounds.x < 0.001f && self->bounds.y < 0.001f && self->text && self->text_size > 0)
            self->bounds = mgl_text_calculate_bounds(self);
    } else {
        self->bounds = (mgl_vec2f){ 0.0f, 0.0f };
    }
}

void mgl_text_set_position(mgl_text *self, mgl_vec2f position) {
    self->position = position;
}

void mgl_text_set_color(mgl_text *self, mgl_color color) {
    self->color = color;
}

mgl_vec2f mgl_text_get_bounds(const mgl_text *self) {
    return self->bounds;
}

static void mgl_text_draw_glyph(mgl_context *context, mgl_font_glyph *glyph, mgl_vec2f position) {
    context->gl.glTexCoord2f(glyph->texture_position.x, glyph->texture_position.y);
    context->gl.glVertex3f(position.x + glyph->position.x, position.y + glyph->position.y, 0.0f);

    context->gl.glTexCoord2f(glyph->texture_position.x + glyph->texture_size.x, glyph->texture_position.y);
    context->gl.glVertex3f(position.x + glyph->position.x + glyph->size.x, position.y + glyph->position.y, 0.0f);

    context->gl.glTexCoord2f(glyph->texture_position.x + glyph->texture_size.x, glyph->texture_position.y + glyph->texture_size.y);
    context->gl.glVertex3f(position.x + glyph->position.x + glyph->size.x, position.y + glyph->position.y + glyph->size.y, 0.0f);

    context->gl.glTexCoord2f(glyph->texture_position.x, glyph->texture_position.y + glyph->texture_size.y);
    context->gl.glVertex3f(position.x + glyph->position.x, position.y + glyph->position.y + glyph->size.y, 0.0f);
}

/* TODO: Use opengl buffer object instead */
/* TODO: Cache texture bind to not bind texture if its already bound and do not bind texture 0 */
void mgl_text_draw(mgl_context *context, mgl_text *text) {
    if(!text->text || text->text_size == 0 || !text->font)
        return;

    mgl_font_glyph glyph;
    mgl_vec2f position = text->position;
    position.y += text->font->character_size;

    context->gl.glColor4ub(text->color.r, text->color.g, text->color.b, text->color.a);
    context->gl.glBindTexture(GL_TEXTURE_2D, text->font->texture.id);
    context->gl.glBegin(GL_QUADS);
    for(size_t i = 0; i < text->text_size;) {
        unsigned char *cp = (unsigned char*)&text->text[i];
        uint32_t codepoint;
        size_t clen;
        if(!mgl_utf8_decode(cp, text->text_size - i, &codepoint, &clen)) {
            codepoint = *cp;
            clen = 1;
        }

        if(codepoint == '\t') {
            if(mgl_font_get_glyph(text->font, ' ', &glyph) == 0) {
                position.x += (glyph.advance * TAB_WIDTH);
            }
        } else if(codepoint == '\n') {
            position.x = text->position.x;
            position.y += text->font->character_size;
        } else {
            if(mgl_font_get_glyph(text->font, codepoint, &glyph) == 0) {
                mgl_text_draw_glyph(context, &glyph, position);
                position.x += glyph.advance;
            }
        }
        i += clen;
    }
    context->gl.glEnd();
    context->gl.glBindTexture(GL_TEXTURE_2D, 0);
}