#include "undamped.h"
#include "../../../shared_cpp/Renderer2d.h"
#include "../../../shared_cpp/types.h"
#include "../../../shared_cpp/WebglContext.h"
#include "../../../shared_cpp/mathlib.h"
#include "../../../shared_cpp/MainLoop.h"
#include <cstdio>
#include <cmath>
#include <emscripten/html5.h>
#include <unistd.h>
#include <pthread.h>
#include <cmath>
#include <cfloat>

namespace Undamped {
    
    struct SpringWeight {
        Mesh2d shape;
        float32 radius = 2.f;
        float32 mass = 1.f;

        void load(Renderer2d* renderer, float32 inMass, Vector4 startColor, Vector4 endColor);
        void update(float32 dtSeconds);
        void render(Renderer2d* renderer);
        void unload();
    };

    struct Spring {
        SpringWeight* weight;

        // -- Rendering
        Mesh2d shape;
        Vertex2d* vertices = NULL;
        int32 numSegments = 0;
        int32 numVertices = 0;

        // -- Spring initial variables
        float32 k = 4; // Spring Constant, in N / m

        // -- Spring runtime variables
		float32 force = 0.f;
        float32 velocity = 0.f;
        float32 position = 0.f;

        void load(Renderer2d* renderer, SpringWeight* inWieight, float32 length, float32 inInitialDisplacement, float32 inK, float32 loopRadius);
        void update(float32 dtSeconds);
        void render(Renderer2d* renderer);
        void unload();
    };

    UndampedInitVariables initVariables;
    void setInitVariables(UndampedInitVariables newVariables) { initVariables = newVariables; }
    UndampedInitVariables getInitVariables() { return initVariables; }
    WebglContext* context;
    Renderer2d renderer;
    MainLoop mainLoop;
    SpringWeight weight;
    Spring spring;

    EM_BOOL onUndampedPlayClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData);
    EM_BOOL onUndampedStopClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData);
    void load();
    void update(float32 deltaTimeSeconds, void* userData);
    void unload();

    void init(WebglContext* inContext) {
        context = inContext;
        emscripten_set_click_callback("#gl_canvas_play_undamped", NULL, false, onUndampedPlayClicked);
        emscripten_set_click_callback("#gl_canvas_stop_undamped", NULL, false, onUndampedStopClicked);
    }

    void load() {
        context->init("#gl_canvas_undamped");
        
        renderer.load(context);

        weight.load(&renderer, initVariables.mass, Vector4 { 55.f, 235.f, 35.f, 255.f }, Vector4 { 235.f, 5.f, 235.f, 255.f });
        spring.load(&renderer, &weight, initVariables.springLength, initVariables.initialDisplacement, initVariables.k, 64.f);

        mainLoop.run(update);
    }

    void update(float32 deltaTimeSeconds, void* userData) {
        // -- Update
        spring.update(deltaTimeSeconds);
        weight.update(deltaTimeSeconds);
	
        // -- Render
        renderer.render();
        weight.render(&renderer);
        spring.render(&renderer);
    }

    void unload() {
        mainLoop.stop();
        renderer.unload();
        weight.unload();
        spring.unload();

        context->destroy();
    }


    void SpringWeight::load(Renderer2d* renderer, float32 inMass, Vector4 startColor, Vector4 endColor) {
        mass = inMass;
        radius = mass * 16.f;
		if (radius > 42) radius = 42.f;
        const int32 numSegments = 96;
        const float32 radiansPerSegment = (2.f * PI) / static_cast<float>(numSegments);
        const int32 numVertices = numSegments * 3;

        float32 t = 0.f;
        float32 tIncrement = 1.f / (numSegments / 2.f);
        startColor = startColor.toNormalizedColor();
        endColor = endColor.toNormalizedColor();

        Vertex2d vertices[numVertices];
        for (int idx = 0; idx < numSegments; idx++) {
            int vIdx = idx * 3;
        
            Vector4 color = lerp(startColor, endColor, t);
            if (idx >= numSegments / 2) {
                t -= tIncrement; 
            } else {
                t += tIncrement;
            }
        
            vertices[vIdx].color = color;
            vertices[vIdx].position = Vector2 { radius * cosf(radiansPerSegment * idx), radius * sinf(radiansPerSegment * idx) };
            vertices[vIdx + 1].color = color;
            vertices[vIdx + 1].position = Vector2 { 0.f, 0.f };
            vertices[vIdx + 2].color = color;
            vertices[vIdx + 2].position = Vector2 { radius * cosf(radiansPerSegment * (idx + 1)), radius * sinf(radiansPerSegment * (idx + 1)) };
        }

        shape.load(vertices, numVertices, renderer);
    }

    void SpringWeight::update(float32 dtSeconds) {
    
    }

    void SpringWeight::render(Renderer2d* renderer) {
        shape.render(renderer);
    }

    void SpringWeight::unload() {
        shape.unload();
    }

    void Spring::load(Renderer2d* renderer, SpringWeight* inWeight, float32 length, float32 initialDisplacement, float32 inK, float32 loopRadius) {
        weight = inWeight;
	    position = initialDisplacement;
        k = inK;
		force = -k * initialDisplacement;
        velocity = sqrtf(k / weight->mass);
        
        const int32 verticesPerSegment = 6;
        numSegments = 256;
        numVertices = numSegments * verticesPerSegment;
        vertices = new Vertex2d[numVertices];

        float32 lengthIncrement = length / static_cast<float32>(numSegments);

        const float32 frequency = 0.25f;
        const float32 loopWidth = 20.f;
        const float32 offset = 0.25f;

        int32 vidx = 0;
		float32 dx = position;
        for (int pidx = 0; pidx < numSegments; pidx++) {
            float32 y1 = lengthIncrement * pidx;
            float32 x1 = loopWidth * sinf(frequency * y1 + offset);

            float32 y2 = y1 + lengthIncrement;
            float32 x2 = loopWidth * sinf(frequency * y2 + offset);

			float32 y1Offset = dx * (1.f - pidx / static_cast<float32>(numSegments));
            float32 y2Offset = dx * (1.f - (pidx + 1) / static_cast<float32>(numSegments));

			y1 += y1Offset;
			y2 += y2Offset;
        
            vertices[vidx++].position = Vector2(x1, y1);
            vertices[vidx++].position = Vector2(x1, y2);
            vertices[vidx++].position = Vector2(x2, y1);
            vertices[vidx++].position = Vector2(x2, y1);
            vertices[vidx++].position = Vector2(x1, y2);
            vertices[vidx++].position = Vector2(x2, y2);
        }

        shape.load(vertices, numVertices, renderer, GL_DYNAMIC_DRAW);
        shape.model = Mat4x4().translateByVec2(Vector2(400, 300));

        weight->shape.model = shape.model.translateByVec2(Vector2(0, -weight->radius + dx));
    }

    void Spring::update(float32 dtSeconds) {
		float32 lastPosition = position;
		force = -k * position;
	    velocity = velocity + (force * dtSeconds) / weight->mass;
		position = position + velocity * dtSeconds;

		float32 dx = position - lastPosition;
        int32 vidx = 0;
        for (int pidx = 0; pidx < numSegments; pidx++) {
            float32 y1Offset = dx * (1.f - pidx / static_cast<float32>(numSegments));
            float32 y2Offset = dx * (1.f - (pidx + 1) / static_cast<float32>(numSegments));
            vertices[vidx++].position.y += y1Offset;
            vertices[vidx++].position.y += y2Offset;
            vertices[vidx++].position.y += y1Offset;
            vertices[vidx++].position.y += y1Offset;
            vertices[vidx++].position.y += y2Offset;
            vertices[vidx++].position.y += y2Offset;
        }

        weight->shape.model = weight->shape.model.translateByVec2(Vector2(0, dx));
    }

    void Spring::render(Renderer2d* renderer) {
        glBindBuffer(GL_ARRAY_BUFFER, shape.vbo);
        glBufferSubData(GL_ARRAY_BUFFER, 0, numVertices * sizeof(Vertex2d), &vertices[0]);

        shape.render(renderer);
    }

    void Spring::unload() {
        shape.unload();
        delete[] vertices;
    }


    EM_BOOL onUndampedPlayClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData) {
        printf("Play clicked\n");
    
        load();
        return true;
    }

    EM_BOOL onUndampedStopClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData) {
        printf("Stop clicked\n");
        unload();
        return true;
    }

}