/*
Copyright (c) 2013 Andrey Penechko

Boost Software License - Version 1.0 - August 17th, 2003

Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
this license the "Software" to use, reproduce, display, distribute,
execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:

The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software, in whole or in part, and
all derivative works of the Software, unless such copies or derivative
works are solely in the form of machine-executable object code generated by
a source language processor.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
*/

module anchovy.gui.guirenderer;

import std.array;
import std.stdio;

import anchovy.graphics;
import anchovy.graphics.texture;
import anchovy.graphics.font.fontmanager;
import anchovy.graphics.shaderprogram;
import anchovy.gui;

string textvshader=`
#version 330 
layout (location = 0) in vec2 Position;
layout (location = 1) in vec2 TexCoord;
uniform vec2 gPosition;
uniform vec2 gHalfTarget;
uniform sampler2D gSampler;
out vec2 TexCoord0;

void main()
{
	gl_Position = vec4(((Position.x+gPosition.x)/gHalfTarget.x)-1, 1-((Position.y+gPosition.y)/gHalfTarget.y), 0.0, 1.0);
	ivec2 texSize = textureSize(gSampler, 0);
	TexCoord0 = TexCoord/texSize;
}`;

string textfshader=`
#version 330 
in vec2 TexCoord0;

out vec4 FragColor;

uniform sampler2D gSampler;
uniform vec4 gColor;

void main()
{
	FragColor = texture2D(gSampler, TexCoord0).r*gColor;
} 	
`;

/// Gives means for rendering widgets and text lines.
class SkinnedGuiRenderer : IGuiRenderer
{
	this(IRenderer renderer, GuiSkin skin)
	{
		_renderer = renderer;
		_fontManager = new FontManager();
		_fontTexture = _fontManager.getFontAtlasTex();
		_textShader = new ShaderProgram(textvshader, textfshader);
		_skin = skin;

		if (!_textShader.compile)
			writeln("Text shader failed compilation: ", _textShader.errorLog);

		_renderer.bindShaderProgram(_textShader);
		checkGlError;
	}

	/// Returns texture that stores cached glyps of all loaded fonts.
	override Texture getFontTexture()
	{
		return _fontTexture;
	}

	/// Returns font manager used by this renderer.
	override ref FontManager fontManager() @property
	{
		return _fontManager;
	}

	GuiSkin skin() @property
	{
		return _skin;
	}

	/// Creates textline with font from current skin.
	/// If font not found then normal font will be used.
	override TextLine createTextLine(string fontName = "normal")
	{
		auto line = new TextLine();
		_lines ~= line;

		line.fontName = fontName;

		Font* font = fontName in _skin.fonts;

		if (font is null)
		{
			font = "normal" in _skin.fonts;
		}

		line.font = *font;

		return line;
	}

	/// Draws background of widget.
	override void drawControlBack(Widget widget, Rect staticRect)
	{
		string styleName = widget.getPropertyAs!("style", string);
		string stateName = widget.getPropertyAs!("state", string);

		GuiStyle* styleptr = styleName in _skin.styles;

		// No style in skin.
		if (styleptr is null)
		{
			_renderer.setColor(Color(255, 255, 255, 255));
			_renderer.fillRect(staticRect);
			_renderer.setColor(Color(255, 0, 0, 255));
			_renderer.drawRect(staticRect);
		}
		else // Widget has style.
		{
			GuiStyle style = *styleptr;

			if (!(stateName in style.states)) // Fallback to deafult.
			{
				stateName = "normal";
			}

			GuiStyleState state = style[stateName];

			TexRectArray[string] geometryList = widget.getPropertyAs!("geometry", TexRectArray[string]);

			TexRectArray* geometry = stateName in geometryList;

			if (geometry is null) // Geometry for current state is no cached yet.
			{
				ivec2 size = widget.getPropertyAs!("size", ivec2);
				TexRectArray newGeometry = buildWidgetGeometry(size, state);

				geometry = &newGeometry;
				geometryList[stateName] = newGeometry;

				widget.setProperty!"geometry"(geometryList);
			}

			_renderer.setColor(Color(255, 255, 255, 255));
			_renderer.drawTexRectArray(*geometry,
										ivec2(staticRect.x - state.outline.left,staticRect.y - state.outline.top),
			                           _skin.texture);
		}
	}

	/// Draws line of text aligning it to the position.
	override void drawTextLine(TextLine line, ivec2 position, in AlignmentType alignment)
	{
		if (!line.isInited)
		{
			return;
		}
		line.update;
		
		int renderX, renderY;

		if (alignment & HoriAlignment.LEFT)
			renderX = position.x;
		else if (alignment & HoriAlignment.CENTER)
			renderX = position.x - (line.width / 2);
		else 
			renderX = position.x - line.width;

		if (alignment & VertAlignment.TOP)
			renderY = position.y + line.height;
		else if (alignment & VertAlignment.CENTER)
			renderY = position.y + (line.height / 2);
		else 
			renderY = position.y;

		_renderer.drawTexRectArray(line.geometry, ivec2(renderX , renderY), _fontTexture, _textShader);
	}

	/// Draws line of text aligning it inside rectangle.
	override void drawTextLine(TextLine line, in Rect area, in AlignmentType alignment)
	{
		if (!line.isInited)
		{
			return;
		}
		line.update;
		
		int renderX, renderY;
		
		if (alignment & HoriAlignment.LEFT)
			renderX = area.x;
		else if (alignment & HoriAlignment.CENTER)
			renderX = area.x + (area.width/2) - (line.width / 2);
		else if (alignment & HoriAlignment.RIGHT)
			renderX = area.x + area.width - line.width;
		else
			renderX = area.x;
		
		if (alignment & VertAlignment.TOP)
			renderY = area.y;
		else if (alignment & VertAlignment.CENTER)
			renderY = area.y + (area.height/2) - (line.height / 2);
		else if (alignment & VertAlignment.BOTTOM)
			renderY = area.y + area.height - line.height;
		else
			renderY = area.y;
		
		_renderer.drawTexRectArray(line.geometry, ivec2(renderX , renderY), _fontTexture, _textShader);
	}

	/// Pushes new clip rect onto stack.
	/// Useful for containers which clips their children.
	/// Must be called when parent begins drawing its children.
	override void pushClientArea(Rect area)
	{
		_clientAreaStack ~= area;
		setClientArea(_clientAreaStack.back);
	}
	
	/// Pops clip rect from stack.
	/// Useful for containers which clips their children.
	/// Must be called when parent ends drawing its children.
	override void popClientArea()
	{
		_clientAreaStack.popBack;

		if (_clientAreaStack.empty)
		{
			glScissor(0, 0, _renderer.windowSize.x, _renderer.windowSize.y);
			return;
		}

		setClientArea(_clientAreaStack.back);
	}

	/// Sets clip rect to given area.
	/// Make sure to call this to reset rendering area for the window.
	override void setClientArea(Rect area)
	{
		glScissor(area.x, _renderer.windowSize.y - area.y - area.height,  area.width, area.height);
	}

	/// Returns internal render.
	IRenderer renderer() @property
	{
		return _renderer;
	}

	/// Creates geometry for given gui style state and size.
	TexRectArray buildWidgetGeometry(ivec2 size, in GuiStyleState state)
	{
		TexRectArray geometry = new TexRectArray;
		RectOffset fb = state.fixedBorders; // defines splitting of texture in 9 pieces.

		int widgetHeight = size.y + state.outline.top + state.outline.bottom;
		int widgetWidth = size.x + state.outline.left + state.outline.right;

		if (fb.left > 0) // left 3 parts
		{

			if (fb.top > 0) // left-top
			{
				Rect texRect;
				with(state.atlasRect)
					texRect = Rect(x, y, fb.left, fb.top);
				geometry.appendQuad(Rect(0, 0, fb.left, fb.top), texRect);
			}
			if (fb.bottom > 0) // left-bottom
			{
				Rect texRect;
				with(state.atlasRect)
					texRect = Rect(x, y + height - fb.bottom, fb.left, fb.bottom);
				geometry.appendQuad(Rect(0, widgetHeight - fb.bottom, fb.left, fb.bottom), texRect);
			}
			if (fb.vertical < widgetHeight) // left
			{
				Rect texRect;
				with(state.atlasRect)
					texRect = Rect(x, y + fb.top, fb.left, height - fb.vertical);
				geometry.appendQuad(Rect(0, fb.top, fb.left, widgetHeight - fb.vertical), texRect);
			}
		}

		if (fb.top > 0 && fb.horizontal < widgetWidth) // top
		{
			Rect texRect;
			with(state.atlasRect)
				texRect = Rect(x + fb.left, y, width - fb.horizontal, fb.top);
			geometry.appendQuad(Rect(fb.left, 0, widgetWidth - fb.horizontal, fb.top), texRect);
		}

		if (fb.horizontal < widgetWidth && fb.vertical < widgetHeight) // center
		{
			Rect texRect;
			with(state.atlasRect)
				texRect = Rect(x + fb.left, y + fb.top, width - fb.horizontal, height - fb.vertical);
			geometry.appendQuad(Rect(fb.left, fb.top, widgetWidth - fb.horizontal, widgetHeight - fb.vertical), texRect);
		}

		if (fb.bottom > 0 && fb.horizontal < widgetWidth) // bottom
		{
			Rect texRect;
			with(state.atlasRect)
				texRect = Rect(x + fb.left, y + height - fb.bottom, width - fb.horizontal, fb.bottom);
			geometry.appendQuad(Rect(fb.left, widgetHeight - fb.bottom, widgetWidth - fb.horizontal, fb.bottom), texRect);
		}

		if (fb.right > 0) // right 3 parts
		{
			if (fb.top > 0) // right-top
			{
				Rect texRect;
				with(state.atlasRect)
					texRect = Rect((x+width) - fb.right, y, fb.right, fb.top);
				geometry.appendQuad(Rect(widgetWidth - fb.right, 0, fb.right, fb.top), texRect);
			}
			if (fb.bottom > 0) // right-bottom
			{
				Rect texRect;
				with(state.atlasRect)
					texRect = Rect((x+width) - fb.right, y + height - fb.bottom, fb.right, fb.bottom);
				geometry.appendQuad(Rect(widgetWidth - fb.right, widgetHeight - fb.bottom, fb.right, fb.bottom), texRect);
			}
			if (fb.vertical < widgetHeight) // right
			{
				Rect texRect;
				with(state.atlasRect)
					texRect = Rect((x+width) - fb.right, y + fb.top, fb.right, height - fb.vertical);
				geometry.appendQuad(Rect(widgetWidth - fb.right, fb.top, fb.right, widgetHeight - fb.vertical), texRect);
			}
		}

		geometry.load;

		return geometry;
	}

private:

	Rect[] _clientAreaStack;
	IRenderer _renderer;
	FontManager _fontManager;
	ShaderProgram _textShader;
	Texture _fontTexture;
	GuiSkin _skin;
	TextLine[] _lines;
}