/*
  ==============================================================================

   This file is part of the JUCE framework examples.
   Copyright (c) Raw Material Software Limited

   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   to use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.

   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
   REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
   AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
   INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
   LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
   OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
   PERFORMANCE OF THIS SOFTWARE.

  ==============================================================================
*/

/*******************************************************************************
 The block below describes the properties of this PIP. A PIP is a short snippet
 of code that can be read by the Projucer and used to generate a JUCE project.

 BEGIN_JUCE_PIP_METADATA

 name:             OpenGLDemo2D
 version:          1.0.0
 vendor:           JUCE
 website:          http://juce.com
 description:      Simple 2D OpenGL application.

 dependencies:     juce_core, juce_data_structures, juce_events, juce_graphics,
                   juce_gui_basics, juce_gui_extra, juce_opengl
 exporters:        xcode_mac, vs2022, vs2026, linux_make, androidstudio,
                   xcode_iphone

 moduleFlags:      JUCE_STRICT_REFCOUNTEDPOINTER=1

 type:             Component
 mainClass:        OpenGLDemo2D

 useLocalCopy:     1

 END_JUCE_PIP_METADATA

*******************************************************************************/

#pragma once

#include "../Assets/DemoUtilities.h"

//==============================================================================
class OpenGLDemo2D final : public Component,
                           private CodeDocument::Listener,
                           private Timer
{
public:
    OpenGLDemo2D()
    {
        setOpaque (true);

        if (auto* peer = getPeer())
            peer->setCurrentRenderingEngine (0);

        openGLContext.attachTo (*getTopLevelComponent());

        addAndMakeVisible (statusLabel);
        statusLabel.setJustificationType (Justification::topLeft);
        statusLabel.setFont (FontOptions (14.0f));

        for (const auto [index, preset] : enumerate (getPresets(), 1))
            presetBox.addItem (preset.name, index);

        addAndMakeVisible (presetLabel);
        presetLabel.attachToComponent (&presetBox, true);

        addAndMakeVisible (presetBox);
        presetBox.onChange = [this] { selectPreset (presetBox.getSelectedItemIndex()); };

        fragmentEditorComp.setOpaque (false);
        fragmentDocument.addListener (this);
        addAndMakeVisible (fragmentEditorComp);

        presetBox.setSelectedItemIndex (0);

        setSize (500, 500);
    }

    ~OpenGLDemo2D() override
    {
        openGLContext.detach();
        shader.reset();
    }

    void paint (Graphics& g) override
    {
        g.fillCheckerBoard (getLocalBounds().toFloat(), 48.0f, 48.0f, Colours::lightgrey, Colours::white);

        if (shader.get() == nullptr || shader->getFragmentShaderCode() != fragmentCode)
        {
            shader.reset();

            if (fragmentCode.isNotEmpty())
            {
                shader.reset (new OpenGLGraphicsContextCustomShader (fragmentCode));

                auto result = shader->checkCompilation (g.getInternalContext());

                if (result.failed())
                {
                    statusLabel.setText (result.getErrorMessage(), dontSendNotification);
                    shader.reset();
                }
            }
        }

        if (shader.get() != nullptr)
        {
            statusLabel.setText ({}, dontSendNotification);

            shader->fillRect (g.getInternalContext(), getLocalBounds());
        }
    }

    void resized() override
    {
        auto area = getLocalBounds().reduced (4);

        statusLabel.setBounds (area.removeFromTop (75));

        area.removeFromTop (area.getHeight() / 2);

        auto presets = area.removeFromTop (25);
        presets.removeFromLeft (100);
        presetBox.setBounds (presets.removeFromLeft (150));

        area.removeFromTop (4);
        fragmentEditorComp.setBounds (area);
    }

    void selectPreset (int preset)
    {
        fragmentDocument.replaceAllContent (preprocessShader (getPresets()[(size_t) preset].fragmentShader));
        startTimer (1);
    }

    std::unique_ptr<OpenGLGraphicsContextCustomShader> shader;

    Label statusLabel, presetLabel  { {}, "Shader Preset:" };
    ComboBox presetBox;
    CodeDocument fragmentDocument;
    CodeEditorComponent fragmentEditorComp  { fragmentDocument, nullptr };
    String fragmentCode;

private:
    OpenGLContext openGLContext;

    enum { shaderLinkDelay = 500 };

    void codeDocumentTextInserted (const String& /*newText*/, int /*insertIndex*/) override
    {
        startTimer (shaderLinkDelay);
    }

    void codeDocumentTextDeleted (int /*startIndex*/, int /*endIndex*/) override
    {
        startTimer (shaderLinkDelay);
    }

    void timerCallback() override
    {
        stopTimer();
        fragmentCode = fragmentDocument.getAllContent();
        repaint();
    }

    struct ShaderPreset
    {
        const char* name;
        const char* fragmentShader;
    };

    static String preprocessShader (String shaderSource)
    {
        return shaderSource.replace ("#lowp#",    OpenGLHelpers::isOpenGLES() ? "lowp" : "")
                           .replace ("#mediump#", OpenGLHelpers::isOpenGLES() ? "mediump" : "")
                           .replace ("#highp#",   OpenGLHelpers::isOpenGLES() ? "highp" : "");
    }

    static Span<const ShaderPreset> getPresets()
    {
        #define SHADER_2DDEMO_HEADER \
            "/*  This demo shows the use of the OpenGLGraphicsContextCustomShader,\n" \
            "    which allows a 2D area to be filled using a GL shader program.\n" \
            "\n" \
            "    Edit the shader program below and it will be \n" \
            "    recompiled in real-time!\n" \
            "*/\n\n"

        static constexpr ShaderPreset presets[]
        {
            {
                "Simple Gradient",

                SHADER_2DDEMO_HEADER
                "void main()\n"
                "{\n"
                "    #mediump# vec4 colour1 = vec4 (1.0, 0.4, 0.6, 1.0);\n"
                "    #mediump# vec4 colour2 = vec4 (0.0, 0.8, 0.6, 1.0);\n"
                "    #mediump# float alpha = pixelPos.x / 1000.0;\n"
                "    gl_FragColor = pixelAlpha * mix (colour1, colour2, alpha);\n"
                "}\n"
            },

            {
                "Circular Gradient",

                SHADER_2DDEMO_HEADER
                "void main()\n"
                "{\n"
                "    #mediump# vec4 colour1 = vec4 (1.0, 0.4, 0.6, 1.0);\n"
                "    #mediump# vec4 colour2 = vec4 (0.3, 0.4, 0.4, 1.0);\n"
                "    #mediump# float alpha = distance (pixelPos, vec2 (600.0, 500.0)) / 400.0;\n"
                "    gl_FragColor = pixelAlpha * mix (colour1, colour2, alpha);\n"
                "}\n"
            },

            {
                "Circle",

                SHADER_2DDEMO_HEADER
                "void main()\n"
                "{\n"
                "    #mediump# vec4 colour1 = vec4 (0.1, 0.1, 0.9, 1.0);\n"
                "    #mediump# vec4 colour2 = vec4 (0.0, 0.8, 0.6, 1.0);\n"
                "    #mediump# float distance = distance (pixelPos, vec2 (600.0, 500.0));\n"
                "\n"
                "    #mediump# float innerRadius = 200.0;\n"
                "    #mediump# float outerRadius = 210.0;\n"
                "\n"
                "    if (distance < innerRadius)\n"
                "        gl_FragColor = colour1;\n"
                "    else if (distance > outerRadius)\n"
                "        gl_FragColor = colour2;\n"
                "    else\n"
                "        gl_FragColor = mix (colour1, colour2, (distance - innerRadius) / (outerRadius - innerRadius));\n"
                "\n"
                "    gl_FragColor *= pixelAlpha;\n"
                "}\n"
            },

            {
                "Solid Colour",

                SHADER_2DDEMO_HEADER
                "void main()\n"
                "{\n"
                "    gl_FragColor = vec4 (1.0, 0.6, 0.1, pixelAlpha);\n"
                "}\n"
            }
        };

        return presets;
    }

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (OpenGLDemo2D)
};
