#include "../../../shared_cpp/OrthographicRenderer.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>

struct Rigidbody {
	Vector2 linearForce = { 0, 0 };
    Vector2 velocity = { 0, 0 };
    Vector2 position = { 0, 0 };
    float32 mass = 1.f;

	float32 torque = 0.f;
	float32 rotationalVelocity = 0.f;
	float32 rotation = 0.f;
	float32 momentOfInertia = 1.f;

    void reset() {
        linearForce = { 0, 0 };
        velocity = { 0, 0 };
		rotationalVelocity = 0.f;
		rotation = 0.f;
    }

    void applyForce(Vector2 force, Vector2 pointOfApplication) {
        linearForce += force;
	    torque += pointOfApplication.getPerp().dot(force);
    }

    void applyGravity() {
		applyForce(Vector2 { 0.f, -100.f }, Vector2 { 0.f, 0.f });
    }

    void update(float32 deltaTimeSeconds) {
        applyGravity();
        
        Vector2 acceleration = linearForce / mass;
        velocity += (acceleration * deltaTimeSeconds);
        position += (velocity * deltaTimeSeconds);
        linearForce = Vector2 { 0.f, 0.f };

		// New: Update the rotational velocity as well
		float32 rotationalAcceleration = torque / momentOfInertia;
		rotationalVelocity += (rotationalAcceleration * deltaTimeSeconds);
		rotation += (rotationalVelocity * deltaTimeSeconds);
		torque = 0.f;
    }
};

struct Rectangle {
	OrthographicShape shape;
    Rigidbody body;
	Vector2 originalPoints[4];
	Vector2 transformedPoints[4];

	void load(OrthographicRenderer* renderer, Vector4 color, float32 width, float32 height) {
        color = color.toNormalizedColor();

		float32 halfWidth = width / 2.f;
		float32 halfHeight = height / 2.f;

	    OrthographicVertex vertices[6];
		vertices[0].position = Vector2 { -halfWidth, -halfHeight };
		vertices[1].position = Vector2 { -halfWidth, halfHeight };
		vertices[2].position = Vector2 { halfWidth, halfHeight };
		vertices[3].position = Vector2 { -halfWidth, -halfHeight };
		vertices[4].position = Vector2 { halfWidth, -halfHeight };
		vertices[5].position = Vector2 { halfWidth, halfHeight };
		
		for (int32 i = 0; i < 6; i++) {
			vertices[i].color = color;
		}

		originalPoints[0] = vertices[0].position;
		originalPoints[1] = vertices[1].position;
		originalPoints[2] = vertices[2].position;
		originalPoints[3] = vertices[4].position;
		
		shape.load(vertices, 6, renderer);
		body.reset();

		body.momentOfInertia = (width * width + height * height) * (body.mass / 12.f);
	}

	void update(float32 dtSeconds) {
		body.update(dtSeconds);
		shape.model = Mat4x4().translateByVec2(body.position).rotate2D(body.rotation);

		// Note: This helps us check if the cursor is within the bounds of the
		// rectangle later on.
		for (int idx = 0; idx < 4; idx++) {
			transformedPoints[idx] = shape.model * originalPoints[idx];
		}
	}

	void render(OrthographicRenderer* renderer) {
		shape.render(renderer);
	}

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

struct Circle {
	OrthographicShape shape;
    Rigidbody body;

	float32 radius = 5.f;

	void load(OrthographicRenderer* renderer, Vector4 color) {
		const int32 numSegments = 36;
		const float32 radiansPerSegment = (2.f * PI) / static_cast<float>(numSegments);
		const int32 numVertices = numSegments * 3;
		
        color = color.toNormalizedColor();

		OrthographicVertex vertices[numSegments * 3];
		for (int idx = 0; idx < numSegments; idx++) {
			int vIdx = idx * 3;
			
			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);
		body.reset();
	}

	void update(float32 dtSeconds) {
		shape.model = Mat4x4().translateByVec2(body.position);
	}

	void render(OrthographicRenderer* renderer) {
		shape.render(renderer);
	}

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

EM_BOOL onPlayClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData);
EM_BOOL onStopClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData);
EM_BOOL onMouseMove(int eventType, const EmscriptenMouseEvent *mouseEvent, void *userData);

void load();
void update(float32 time, void* userData);
void unload();

WebglContext context;
OrthographicRenderer renderer;
MainLoop mainLoop;
Rectangle rectangle;
Circle pointer;
bool isIntersectingPointer = false;

int main() {
	context.init("#gl_canvas");
    emscripten_set_click_callback("#gl_canvas_play", NULL, false, onPlayClicked);
    emscripten_set_click_callback("#gl_canvas_stop", NULL, false, onStopClicked);
    emscripten_set_mousemove_callback("#gl_canvas", NULL, false, onMouseMove);
	
    return 0;
}

void load() {
    renderer.load(&context);

	rectangle.load(&renderer, Vector4 { 55.f, 235.f, 35.f, 255.f }, 128.f, 64.f);
	rectangle.body.position = Vector2 { context.width / 3.f, context.height / 3.f };
	rectangle.body.velocity = Vector2 { 100.f, 250.f };

	pointer.load(&renderer, Vector4 { 25.f, 235.f, 235.f, 255.f });

    mainLoop.run(update);
}

bool isPointInRectangle(Vector2 p, Rectangle r) {
	// https://math.stackexchange.com/a/190373
	Vector2 A = r.transformedPoints[0];
	Vector2 B = r.transformedPoints[1];
	Vector2 D = r.transformedPoints[3];

	float32 amDotAb = (p - A).dot(B - A);
	float32 abDotAb = (B - A).dot(B - A);

	float32 amDotAd = (p - A).dot(D - A);
	float32 aDDotAd = (D - A).dot(D - A);

	return amDotAb > 0 && amDotAb < abDotAb && amDotAd > 0 && amDotAd < aDDotAd;
	
}

void update(float32 deltaTimeSeconds, void* userData) {
    rectangle.update(deltaTimeSeconds);
	pointer.update(deltaTimeSeconds);

	if (isPointInRectangle(pointer.body.position, rectangle)) {
		if (!isIntersectingPointer) {
			isIntersectingPointer = true;
			Vector2 pointOfApplication = pointer.body.position - rectangle.body.position;
			rectangle.body.applyForce(pointer.body.linearForce, pointOfApplication);
		}
	} else if (isIntersectingPointer) {
		isIntersectingPointer = false;
	}
		

    // Check collisions with walls so we don't go out of the scene. Simply reflect here.
    if (rectangle.body.position.x <= 0.f) {
        rectangle.body.position.x = 0.f;
        rectangle.body.velocity = rectangle.body.velocity - Vector2 { 1.f, 0.f } * (2 * (rectangle.body.velocity.dot(Vector2 { 1.f, 0.f })));
    }
    if (rectangle.body.position.y <= 0.f) {
        rectangle.body.position.y = 0.f;
        rectangle.body.velocity = rectangle.body.velocity - Vector2 { 0.f, 1.f } * (2 * (rectangle.body.velocity.dot(Vector2 { 0.f, 1.f })));
    } 
    if (rectangle.body.position.x >= 800.f) {
        rectangle.body.position.x = 800.f;
        rectangle.body.velocity = rectangle.body.velocity - Vector2 { -1.f, 0.f } * (2 * (rectangle.body.velocity.dot(Vector2{ -1.f, 0.f })));
    }
    if (rectangle.body.position.y >= 600.f) {
        rectangle.body.position.y = 600.f;
        rectangle.body.velocity = rectangle.body.velocity - Vector2 { 0.f, -1.f } * (2 * (rectangle.body.velocity.dot(Vector2 { 0.f, -1.f }))) ;
    }
	
	// Renderer
	renderer.render();
    rectangle.render(&renderer);
	pointer.render(&renderer);
}

void unload() {
    mainLoop.stop();
    renderer.unload();
    rectangle.unload();
	pointer.unload();
}

//
// Interactions with DOM handled below
//
EM_BOOL onPlayClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData) {
    printf("Play clicked\n");
    
    load();
    return true;
}

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

EM_BOOL onMouseMove(int eventType, const EmscriptenMouseEvent *mouseEvent, void *userData) {
	if (!mainLoop.isRunning) {
		return true;
	}

	pointer.body.linearForce.x = static_cast<float32>(mouseEvent->movementX) * 1000.f;
	pointer.body.linearForce.y = static_cast<float32>(-mouseEvent->movementY) * 1000.f;

	pointer.body.position.x = static_cast<float32>(mouseEvent->targetX);
	pointer.body.position.y = static_cast<float32>(600.f - mouseEvent->targetY);

	return true;
}