package org.dark.shaders.invert;

import com.fs.starfarer.api.combat.ViewportAPI;
import com.fs.starfarer.api.input.InputEventAPI;

import java.util.List;

import org.dark.shaders.util.ShaderAPI;
import org.dark.shaders.util.ShaderHelper;
import org.dark.shaders.util.ShaderLib;

import static org.lwjgl.opengl.GL20.*;

public class InvertShader implements ShaderAPI {

    private int program;
    private boolean enabled = false;
    private boolean active = false;

    @Override
    public void renderInWorldCoords(ViewportAPI viewport) {
        // Stub
    }

    @Override
    public void renderInScreenCoords(ViewportAPI viewport) {
        // Stub
    }

    @Override
    public void advance(float amount, List<InputEventAPI> events) {
        if (!enabled) {
            return;
        }

        for (InputEventAPI event : events) {
            if (event.isConsumed()) {
                continue;
            }

            if (event.isKeyDownEvent() && event.getEventValue() == org.lwjgl.input.Keyboard.KEY_PERIOD) {
                active = !active;
                event.consume();
                break;
            }
        }

        if (!active) {
            return;
        }

        invertScreen();
    }

    @Override
    public void initCombat() {
    }

    @Override
    public RenderOrder getRenderOrder() {
        return RenderOrder.DISTORTED_SPACE;
    }

    public InvertShader() {
        if (!ShaderLib.areShadersAllowed()) {
            return;
        }

        String vertShader = "#version 110\n"
                + "\n"
                + "void main() {\n"
                + "    gl_Position = ftransform();\n"
                + "    gl_TexCoord[0] = gl_MultiTexCoord0;\n"
                + "}";

        String fragShader = "#version 110\n"
                + "\n"
                + "uniform sampler2D tex;\n"
                + "uniform vec2 boundary;\n"
                + "\n"
                + "vec2 coord = gl_TexCoord[0].xy;\n"
                + "\n"
                + "void main() {\n"
                + " if (coord.x <= boundary.x && coord.y <= boundary.y) {\n"
                + "     vec4 color = texture2D(tex, coord);\n"
                + "     gl_FragColor = vec4(1.0 - color.r, 1.0 - color.g, 1.0 - color.b, 1.0);\n"
                + " }\n"
                + "}";

        program = ShaderLib.loadShader(vertShader, fragShader);

        if (program == 0) {
            return;
        }

        enabled = true;
    }

    private void invertScreen() {
        ShaderLib.beginDraw(program);

        int index;
        index = glGetUniformLocation(program, "tex");
        glUniform1i(index, 0);
        index = glGetUniformLocation(program, "boundary");
        glUniform2f(index, ShaderLib.getVisibleU(), ShaderLib.getVisibleV());

        ShaderLib.screenDraw();

        ShaderLib.exitDraw();
    }
}