// Copyright (C) 2012-2015 ChaosForge Ltd
// http://chaosforge.org/
//
// This file is part of Nova libraries. 
// For conditions of distribution and use, see copying.txt file in root folder.

#include "nv/gfx/texture_font.hh"

#include "nv/lib/freetype2.hh"
#include "nv/core/logging.hh"

using namespace nv;

#define NV_CHECK_FREETYPE_ERROR( error, ... ) \
if ( error != 0 ) { \
	NV_LOG_CRITICAL( "freetype : ", __VA_ARGS__ ); \
	NV_ABORT( "freetype : freetype library error!" ); \
}

texture_glyph::texture_glyph()
	: 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_glyph::get_kerning( const uint16 other )
{
	auto i = kerning.find( other );
	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_hinting( true ), m_filtering( true ), m_rlibrary( nullptr ), m_rface( nullptr )
{
	load_freetype_library();
	size_t hres = 64;
	FT_Error error;
	FT_Matrix matrix = { 
		static_cast<int>((1.0/hres) * 0x10000L),
		static_cast<int>((0.0)      * 0x10000L),
		static_cast<int>((0.0)      * 0x10000L),
		static_cast<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( reinterpret_cast<FT_Library*>(&m_rlibrary) );
	NV_CHECK_FREETYPE_ERROR( error, "error on FT_Init_FreeType, code - ", error );

	error = FT_New_Face( reinterpret_cast<FT_Library>(m_rlibrary), filename, 0, reinterpret_cast<FT_Face*>(&m_rface) );
	NV_CHECK_FREETYPE_ERROR( error, "error on FT_New_Face, code - ", error );

	error = FT_Set_Char_Size( reinterpret_cast<FT_Face>(m_rface), int(size*64), 0, 72*64, 72 );
	NV_CHECK_FREETYPE_ERROR( error, "error on FT_Set_Char_Size, code - ", error );

    FT_Set_Transform( reinterpret_cast<FT_Face>(m_rface), &matrix, NULL );

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

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

static uint8* convert_to_rgba(uint8* rgb, const int lines, const int line_count, const int line_bpitch )
{
	uint8* result = new uint8[ lines * line_count * 4 ];
	uint8* rgba   = result;
	for(int l=0; l<lines; ++l) 
	{
		for(int c=0; c<line_count; ++c)
		{
			for(int j=0; j<3; ++j) {
				rgba[j]  = rgb[j];
			}
			rgba[3] = uint8( uint16( rgb[0] + rgb[1] + rgb[2] ) / 3 );
			rgba += 4;
			rgb  += 3;
		}
		rgb += line_bpitch - ( 3 * line_count );
	}
	return result;
}

bool texture_font::load_glyphs( string_view codes )
{
	FT_Face face = reinterpret_cast<FT_Face>( m_rface );
	size_t depth = m_atlas->get_depth();
	vec2 asize   = vec2( 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( reinterpret_cast<FT_Library>( m_rlibrary ), FT_LCD_FILTER_LIGHT );
		flags |= FT_LOAD_TARGET_LCD;
		if ( m_filtering )
		{
			FT_Library_SetLcdFilterWeights( reinterpret_cast<FT_Library>( m_rlibrary ), m_lcd_weights );
		}
	} 

	for ( char ch : codes )
	{
		uint16 c = static_cast<uint16>( ch );
		FT_UInt glyph_index = FT_Get_Char_Index( face, c ); 
		FT_Error error = FT_Load_Glyph( face, glyph_index, flags ); 
		NV_CHECK_FREETYPE_ERROR( error, "error on FT_Load_Glyph, gylph '", c ,"' code - ", error );

		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;
		int reg_width       = ft_bitmap_width / (depth > 3 ? 3 : int( depth ) );

		ivec2 gsize( reg_width + 1, ft_bitmap_rows + 1 ); 
		region r = m_atlas->get_region( gsize );
		if ( r.pos.x < 0 ) 
		{
			NV_LOG_CRITICAL( "texture_font : atlas full while loading glyphs, gylph '", c, "' r.pos.x = ", r.pos.x );
			NV_ABORT( "texture_font : atlas full while loading gylphs!" );
		}
		if (depth == 4)
		{
			r.size.x -= 1;
			r.size.y -= 1;
			uint8* data = convert_to_rgba(ft_bitmap.buffer, r.size.y, r.size.x, ft_bitmap.pitch );
			m_atlas->set_region( r, data );
			delete data;
		}
		else
		{
			r.size.x -= 1;
			r.size.y -= 1;
			m_atlas->set_region( r, ft_bitmap.buffer, ft_bitmap.pitch );
		}

		texture_glyph* g = &( m_glyphs[c] );

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

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

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

void texture_font::generate_kerning()
{

}