// Copyright (C) 2012-2013 ChaosForge / Kornel Kisielewicz
// http://chaosforge.org/
//
// This file is part of NV Libraries.
// For conditions of distribution and use, see copyright notice in nv.hh

#include <stdexcept>

#include "nv/gl/texture_font.hh"
#include "nv/lib/freetype2.hh"

using namespace nv;

texture_gylph::texture_gylph()
	: charcode(0), size(0,0), offset(0,0), advance(0.f,0.f), tl(0.f,0.f), br(0.f,0.f)
{
}

float texture_gylph::get_kerning( const uint16 charcode )
{
	auto i = kerning.find( charcode );
	return i != kerning.end() ? i->second : 0.0f;
}

texture_font::texture_font( texture_atlas* atlas, const char * filename, float size )
	: m_atlas( atlas ), m_filename(filename), m_size( size ), 
	m_height(0), m_linegap(0), m_ascender(0), m_descender(0),
	m_rlibrary( nullptr ), m_rface( nullptr ), m_hinting( true ), m_filtering( true )
{
	size_t hres = 64;
	FT_Error error;
	FT_Matrix matrix = { 
		(int)((1.0/hres) * 0x10000L),
		(int)((0.0)      * 0x10000L),
		(int)((0.0)      * 0x10000L),
		(int)((1.0)      * 0x10000L) 
	};

	m_lcd_weights[0] = 0x10;
	m_lcd_weights[1] = 0x40;
	m_lcd_weights[2] = 0x70;
	m_lcd_weights[3] = 0x40;
	m_lcd_weights[4] = 0x10;
	 
	error = FT_Init_FreeType( (FT_Library*)(&m_rlibrary) );
	if ( error ) throw std::runtime_error( "FT_Error" );

	error = FT_New_Face( (FT_Library)(m_rlibrary), filename, 0, (FT_Face*)(&m_rface) );
	if ( error ) throw std::runtime_error( "FT_Error" );

	error = FT_Set_Char_Size( (FT_Face)(m_rface), (int)(size*64), 0, 72*64, 72 ); 
	if ( error ) throw std::runtime_error( "FT_Error" );

    FT_Set_Transform( (FT_Face)(m_rface), &matrix, NULL );

    FT_Size_Metrics metrics = ((FT_Face)(m_rface))->size->metrics; 
    m_ascender = (metrics.ascender >> 6) / 100.0;
    m_descender = (metrics.descender >> 6) / 100.0;
    m_height = (metrics.height >> 6) / 100.0;
    m_linegap = m_height - m_ascender + m_descender; 
}

const texture_gylph* texture_font::get_gylph( uint16 charcode ) const
{
	auto i = m_gylphs.find( charcode );
	if ( i == m_gylphs.end() )
	{
		return nullptr;
	}
	return &(i->second);
}

bool texture_font::load_glyphs( const std::string& codes )
{
	FT_Face face     = (FT_Face)(m_rface);
	size_t depth     = m_atlas->get_depth();
	glm::ivec2 asize = m_atlas->get_size();
	FT_Int32 flags = 0; 
	flags |= FT_LOAD_RENDER; 
	if( !m_hinting )
	{
		flags |= FT_LOAD_NO_HINTING | FT_LOAD_NO_AUTOHINT;
	}
	else
	{
		flags |= FT_LOAD_FORCE_AUTOHINT;
	} 

	if( m_atlas->get_depth() == 3 )
	{
		FT_Library_SetLcdFilter( (FT_Library)(m_rlibrary), FT_LCD_FILTER_LIGHT );
		flags |= FT_LOAD_TARGET_LCD;
		if ( m_filtering )
		{
			FT_Library_SetLcdFilterWeights( (FT_Library)(m_rlibrary), m_lcd_weights );
		}
	} 

	for ( char c : codes )
	{
		FT_UInt glyph_index = FT_Get_Char_Index( face, c ); 
		FT_Error error = FT_Load_Glyph( face, glyph_index, flags ); 
		if ( error ) throw std::runtime_error( "FT_Error while loading gylphs" );

		FT_GlyphSlot slot   = face->glyph;
		FT_Bitmap ft_bitmap = slot->bitmap;
		int ft_bitmap_width = slot->bitmap.width;
		int ft_bitmap_rows  = slot->bitmap.rows;
		int ft_glyph_top    = slot->bitmap_top;
		int ft_glyph_left   = slot->bitmap_left;

		glm::ivec2 gsize( ft_bitmap_width/depth + 1, ft_bitmap_rows + 1 ); 
		region r = m_atlas->get_region( gsize );
		if ( r.pos.x < 0 ) 
		{
			throw std::runtime_error( "Atlas full while loading gylphs" );
		}
		r.size.x -= 1;
		r.size.y -= 1;
		m_atlas->set_region( r, ft_bitmap.buffer, ft_bitmap.pitch );

		m_gylphs[ c ] = texture_gylph();
		texture_gylph* g = &(m_gylphs.find( c )->second);

		g->charcode = c;
		g->size     = gsize;
		g->offset   = glm::ivec2( ft_glyph_left, ft_glyph_top );
		g->tl       = glm::vec2( r.pos.x/(float)asize.x, r.pos.y/(float)asize.y );
		g->br       = glm::vec2( ( r.pos.x + gsize.x )/(float)asize.x, (r.pos.y + gsize.y )/(float)asize.y );

		// Discard hinting to get advance
		FT_Load_Glyph( face, glyph_index, FT_LOAD_RENDER | FT_LOAD_NO_HINTING);
		slot = face->glyph;
		g->advance = glm::ivec2( slot->advance.x/64.0, slot->advance.y/64.0 );
	}
	generate_kerning();
	return true;
}

texture_font::~texture_font()
{
	if ( m_rface )    FT_Done_Face( (FT_Face)(m_rface) );
	if ( m_rlibrary ) FT_Done_FreeType( (FT_Library)(m_rlibrary) );
}

void texture_font::generate_kerning()
{

}