#include "pch.h"
#include "font.h"

std::map<kFont, Font> FontManager::m_fonts;

bool Font::load(const char* ttf)
{
    FILE* font_file = fopen(ttf, "rb");
    if (font_file)
    {
        fseek(font_file, 0, SEEK_END);
        long sz = ftell(font_file);
        auto data = std::make_unique<uint8_t[]>(sz);
        fseek(font_file, 0, SEEK_SET);
        auto bytes = fread(data.get(), 1, sz, font_file);
        assert(bytes==sz);
        auto bitmap = std::make_unique<uint8_t[]>(w*h);
        chars.resize(num_chars);
        int ret = stbtt_BakeFontBitmap(data.get(), 0, 50, bitmap.get(), w, h, start_char, num_chars, chars.data());
        font_tex.create(w, h, GL_RED, bitmap.get());
        fclose(font_file);
        return true;
    }
    return false;
}

bool FontManager::load(kFont id, const char *ttf)
{
    return m_fonts[id].load(ttf);
}

const Font& FontManager::get(kFont id)
{
    return m_fonts[id];
}

bool TextMesh::create()
{
    glGenBuffers(2, font_buffers);
    glGenVertexArrays(1, &font_array);
    
    glBindVertexArray(font_array);
    glEnableVertexAttribArray(0);
    glEnableVertexAttribArray(1);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, font_buffers[1]);
    glBindBuffer(GL_ARRAY_BUFFER, font_buffers[0]);
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(glm::vec4), (GLvoid*)0);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(glm::vec4), (GLvoid*)(sizeof(float)*2));
    glBindVertexArray(0);
    return true;
}

void TextMesh::update(kFont id, const char* text)
{
    auto& f = FontManager::get(id);
    if (f.chars.size())
    {
        static char str[64];
        static int counter = 0;
        counter++;
        sprintf(str, "frame %04d", counter);
        const auto len = strlen(str);
        float x = 0;
        float y = 0;
        std::vector<glm::vec4> v;
        std::vector<GLushort> idx;
        for (int i = 0; i < len; i++)
        {
            int c = str[i] - f.start_char;
            stbtt_aligned_quad q;
            stbtt_GetBakedQuad((stbtt_bakedchar*)f.chars.data(), f.w, f.h, c, &x, &y, &q, true);
            auto n = v.size();
            v.emplace_back(q.x0, q.y1, q.s0, q.t1);
            v.emplace_back(q.x0, q.y0, q.s0, q.t0);
            v.emplace_back(q.x1, q.y0, q.s1, q.t0);
            v.emplace_back(q.x1, q.y1, q.s1, q.t1);
            idx.push_back(n+0);
            idx.push_back(n+1);
            idx.push_back(n+2);
            idx.push_back(n+0);
            idx.push_back(n+2);
            idx.push_back(n+3);
        }
        font_array_count = (int)idx.size();
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, font_buffers[1]);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, idx.size() * sizeof(GLushort), idx.data(), GL_STATIC_DRAW);
        glBindBuffer(GL_ARRAY_BUFFER, font_buffers[0]);
        glBufferData(GL_ARRAY_BUFFER, v.size() * sizeof(glm::vec4), v.data(), GL_STATIC_DRAW);
        glBindBuffer(GL_ARRAY_BUFFER, 0);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
    }
}