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#include "Physics.hh"

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#include "Engine.hh"

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#include "GameState.hh"

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#include <algorithm>

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#include <functional>

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#include <cmath>

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#include <assert.h>

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PhysicsWorld::PhysicsWorld (Vector gravity, Vector dimensions)

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    : tick_timer(PHYSICS_TICK_MS), tick_counter(0), gravity(gravity), dimensions(dimensions), terrain(dimensions.x, std::vector<TerrainType>(dimensions.y, DIRT)) {

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    generateTerrain(1337);

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    16

    slots.connect(tick_timer.sig_timer(), this, &PhysicsWorld::tick);

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    tick_timer.enable();

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}

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    20

void PhysicsWorld::addObject (PhysicsObject *object) {

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    objects.push_back(object);

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}

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void PhysicsWorld::tick () {

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    //    Engine::log(DEBUG, "physics.apply_force") << "*tick*";

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    for (std::vector<PhysicsObject*>::iterator i = objects.begin(); i != objects.end(); i++) {

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        (*i)->tick(); 

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    }

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    31

    tick_counter++;

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}

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uint32_t PhysicsWorld::getTick (void) {

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    return tick_counter;

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}

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    38

PhysicsObject::PhysicsObject (PhysicsWorld &world, float mass, 

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                              Vector position, Vector velocity)

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    : world(world), mass(mass), position(position), 

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      velocity(velocity), facingRight(true), inAir(true) {

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    world.addObject(this);

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}

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    46

Vector PhysicsObject::walk (bool right) {

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    Vector cursor = right ? this->position + Vector(1,0) : this->position + Vector(-1,0);

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    Vector reached = this->position;

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    //for(int steps = 0; steps < 3; steps++) {

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    // Go up but not if the wall is over two pixels

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    if(world.getType(cursor) != EMPTY) {

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        for(int height = 0, max = 3; height < max+42; height++) {

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            if(height >= max)

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                return reached;

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            cursor.y--;

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            if(world.getType(cursor) == EMPTY) {

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                // Check that the other parts of the worm don't collide with anything

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                if(possibleLocation(cursor)) {

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                    reached = cursor;

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                    continue;

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                } else {

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                    // Can't get any further

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                    return reached;

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                }

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            }

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        }

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    } else {

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        if(possibleLocation(cursor)) {

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            reached = cursor;

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        }

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        // Start checking if the lower squares are empty

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        for(int depth = 0, max = 3; depth < max+42; depth++) {

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            if(depth >= max) {

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                // We can start a free fall now

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                //

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                // TODO it should be set inAir if it falls from a cliff

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                this->inAir = true;

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    85

                // Put some speed there to make loke smoother

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                //this->velocity.y = -5;

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                return reached;

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            }

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            cursor.y++;

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            if(world.getType(cursor) == EMPTY) {

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                // Check that the other parts of the worm don't collide with anything

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                if(possibleLocation(cursor)) {

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                    reached = cursor;

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                    continue;

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                } else {

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                    // Can't get any further

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                    return reached;

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                }

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            }

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        }

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    }      

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   104

    //    cursor.x += right ? 1 : -1;

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    //}

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    return reached;

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}

   108

   109

void PhysicsObject::jump () {

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    // Jump only if player is "on the ground"

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    if (!this->inAir) {

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 	velocity.y = -100;

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	inAir = true;

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    }

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}

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   117

bool PhysicsObject::possibleLocation (Vector loc) {

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    for(unsigned int i = 0; i < this->shape.size(); i++) {

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        if(world.getType(loc+shape[i]) != EMPTY)

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            return false;

   121

    }

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    return true;

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}

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   125

/**

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 * Updates object speed and position. This function organises force

   127

 * integration and collision detection.

   128

 */   

   129

void PhysicsObject::updatePosition () {

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   131

    // Add gravity to the force queue

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    forceq.push(world.gravity);

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   134

    // Go trough every force in the queue

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    Force total;

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    posAfterTick = position;

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    velAfterTick = velocity;

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    while (!forceq.empty()) {

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        total += forceq.front();

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        forceq.pop();

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    }

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   143

    // TODO: This is _ugly_ (but not so ugly as the last one I think)

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    // hack. I think we should handle walking from the collision

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    // detection code.

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   147

    if (!this->inAir) {

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        if (total.x != 0)

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            this->position = walk(total.x > 0);

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        return; // argh

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    }

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    integrate(total, PHYSICS_TICK_MS);

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    Vector newPosition = posAfterTick /*+ (velAfterTick * PHYSICS_TICK_MS)/1000*/;

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    this->velocity = velAfterTick;

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    // Collision detection

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    bool collided = false;

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    const Vector diffVec = newPosition-position;

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    const Vector unitVector = diffVec / diffVec.length();

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    Vector reached = position;

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   166

    while ((position-reached).length() < diffVec.length()) {

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        // Check if any of the shapes points collide

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        for (uint64_t i = 0; i < shape.size(); i ++) {

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            if (world.getType(reached+shape[i]) != EMPTY) {  // Collision

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                this->bounce(world.getNormal(reached+shape[i], reached-unitVector+shape[i]));

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                reached = reached - unitVector; // Return to last point

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                collided = true;

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                this->velocity *= COLLISION_ELASTICITY;

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                if (this->velocity.length() < PLAYER_MIN_SPEED) {

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                    this->inAir = false;

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                    this->velocity = Vector(0,0);

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                }

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                break;

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            }

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        }

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        if (collided)

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            break;

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        reached += unitVector;

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    }

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   186

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    /*

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      bool collided = false;

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      //goes 1 unit forward every step and check if has hit anything

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      Vector unitVector = (newPosition-position) / (newPosition-position).length();

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      Vector tmpVector = position;

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      Vector reached = position;

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      int steps = (int) (newPosition-position).length() + 2;

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      //Engine::log(DEBUG, "physics.update_position") << unitVector-newPosition;

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      //Vector foo = position+unitVector*steps-newPosition;

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      //Engine::log(DEBUG, "PhysicsObject.updatePosition") << "Virhe: "<< foo;

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      for(int i = 0; i < steps; i++) {

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      tmpVector += unitVector;

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      float minVelocity = 10;

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      // Check if any of the four corners of the worm collide

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      for(int sh = 0; sh < 4; sh++) {

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      if(world.getType(tmpVector+shape[sh]) != EMPTY) {

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      reached = position + unitVector*(i-1);

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      collided = true;

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      this->bounce(world.getNormal(tmpVector+shape[sh], tmpVector-unitVector+shape[sh]));

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      this->velocity *= 0.4;

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      if(abs(this->velocity.x) < minVelocity && (abs(this->velocity.y) < minVelocity)) {

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      this->inAir = false;

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      this->velocity = Vector(0,0);

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      }

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      break;

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      }

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      }

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      if(collided)

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      break;

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      }

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    */

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    // In case of some float error check the final coordinate

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    if(!collided) {

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        if(world.getType(newPosition+shape[0]) != EMPTY || (world.getType(newPosition+shape[1]) != EMPTY) 

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           || (world.getType(newPosition+shape[2]) != EMPTY) || (world.getType(newPosition+shape[3]) != EMPTY)) {

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            Engine::log(DEBUG, "physics.update_position") << "didnt hit";

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            // There was error, and there is ground

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            //newPosition = tmpVector;

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        } else {

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            // This means everything was ok, so no need to do anything

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        }

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    } else {

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        newPosition = reached;

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        onCollision();

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        //this->velocity = Vector(0, 0);

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        //TODO: it shouldn't just stop on collision

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    }

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    this->position = newPosition;

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}

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/**

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 * Gets the index of the given coordinate direction

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 * referring to the DIRECTIONS table in Physics.hh

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 */

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int getDirectionIndex (Vector dir) {

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    if(dir.x == 0 && dir.y == -1) {

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        return 0;

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    } else if(dir.x == 1 && dir.y == -1) {

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        return 1;

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    } else if(dir.x == 1 && dir.y == 0) {

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        return 2;

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    } else if(dir.x == 1 && dir.y == 1) {

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        return 3;

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    } else if(dir.x == 0 && dir.y == 1) {

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        return 4;

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    } else if(dir.x == -1 && dir.y == 1) {

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        return 5;

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    } else if(dir.x == -1 && dir.y == 0) {

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        return 6;

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    } else if(dir.x == -1 && dir.y == -1) {

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        return 7;

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    }

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    Engine::log(DEBUG, "physics.getDirectionIndex ") << "invalid direction: " << dir;

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    return 0;

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}

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/**

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 * Computes hitten wall's normal. Calculated from 3*3 grid

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 */

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Vector PhysicsWorld::getNormal (Vector hitPoint, Vector prevPoint) {

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    // Search free points with bfs and put them to vector

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    std::vector<Vector> frees;

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    Vector hit(hitPoint);

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    Vector prev(prevPoint);

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    assert(hit != prev);

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    int dirIdx = getDirectionIndex(prev.roundToInt() - hit.roundToInt());

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    //float tmp1 = hit.x-prev.x;

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    //float tmp2 = hit.y-prev.y;

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    //    Engine::log(DEBUG, "physics.getNormal ") << dirIdx << " " << tmp1 << " " << tmp2;

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   288

    for(int i = 1; i <= 2; i++) {

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        if(getType(hit+DIRECTIONS[(dirIdx+i) % 8]) == EMPTY)

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            frees.push_back(DIRECTIONS[(dirIdx+i) % 8]);

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        else 

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            break;

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    }

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    for(int i = 1; i <= 2; i++) {

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        if(getType(hit+DIRECTIONS[(dirIdx-i+8) % 8]) == EMPTY)

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            frees.push_back(DIRECTIONS[(dirIdx-i+8) % 8]);

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        else

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            break;

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    }

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    frees.push_back(DIRECTIONS[dirIdx]);

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    Vector normal(0,0);

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    for(unsigned int i = 0; i < frees.size(); i++) {

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        normal += frees[i];

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    }

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    Engine::log(DEBUG, "physics.getNormal ") << "normal: " << normal;

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    return normal;

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}

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/**

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 * Bounces from straight wall in any direction.

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 * Direction given as normal of that wall

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 */

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// TODO Bounce doesnt work kun oikealle tai vasemmalle alaviistoon mennään suoralla (tangentaalinen arvo väärän suuntainen)

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void PhysicsObject::bounce (Vector normal) {

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    Vector tangent(normal.y, -normal.x);

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    Vector tprojection = tangent*(velocity * tangent) / (tangent.length()*tangent.length());

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    Vector nprojection = normal*(velocity * normal) / (normal.length()*normal.length());

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    velocity = tprojection - nprojection;

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}

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/**

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 * Integrates given force over time and stores new position to

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 * posAfterTick and new velocity to velAfterTick.

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 * @param force Force vector.

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 * @param dt The time the force is applied (<=PHYSICS_TICK_MS)

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 */

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void PhysicsObject::integrate(Force force, TimeMS dt) {

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    Derivative tmpd;

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    Derivative k1 = evaluate(force, 0, tmpd);

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    Derivative k2 = evaluate(force, 0.5f*dt, k1);

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    Derivative k3 = evaluate(force, 0.5f*dt, k2);

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    Derivative k4 = evaluate(force, dt, k3);

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   335

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    const Vector dxdt = (k1.dx + (k2.dx + k3.dx) * 2.0f + k4.dx) * 1.0f/6.0f;

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    const Vector dvdt = (k1.dv + (k2.dv + k3.dv) * 2.0f + k4.dv) * 1.0f/6.0f;

   338

   339

    //    Engine::log(DEBUG, "PhysicsObject.integrate") << "Changes: "<< dxdt << " " << dvdt << " Time: " <<dt;

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    posAfterTick = posAfterTick + (dxdt * dt)/1000;

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    velAfterTick = velAfterTick + (dvdt * dt)/1000;

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    //Engine::log(DEBUG, "PhysicsObject.integrate") << "velAfterTick: " << velAfterTick;

   343

}

   344

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Derivative PhysicsObject::evaluate(Force force, TimeMS dt, Derivative &d) {

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    Vector curPos = posAfterTick + (d.dx*dt)/1000;

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    Vector curVel = velAfterTick + (d.dv*dt)/1000;

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   349

    Derivative out;

   350

    out.dx = curVel;

   351

    out.dv = acceleration(force);

   352

    //Engine::log(DEBUG, "PhysicsObject.evaluate") << "Out.dx: " << out.dx;

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    return out;

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}

   355

   356

Vector PhysicsObject::acceleration(const Force &force) {

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    return (force/mass);

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}

   359

   360

void PhysicsObject::applyForce (Force force) {

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    // Add applied force to the queue

   362

    forceq.push(force);

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}

   364

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void PhysicsObject::changeAim(float da) {

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    this->aim += da;

   367

   368

    if (this->aim > PLAYER_AIM_MAX) this->aim = PLAYER_AIM_MAX;

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    if (this->aim < PLAYER_AIM_MIN) this->aim = PLAYER_AIM_MIN;

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    //Engine::log(DEBUG, "PhysicsObject.changeAim") << "Player aim: " << this->aim;

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}

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void PhysicsObject::setFacing(bool facingRight) {

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    //Engine::log(DEBUG, "PhysicsObject.setFacing") << "Facing: " << right;

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    this->facingRight = facingRight;

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}

   377

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void PhysicsObject::updatePhysics (Vector position, Vector velocity, bool inAir) {

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    this->position = position;

   380

    this->velocity = velocity;

   381

    this->inAir = inAir;

   382

}

   383

   384

Vector PhysicsObject::getPosition () {

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    return this->position;

   386

}

   387

   388

bool PhysicsObject::getFacing() {

   389

    return this->facingRight;

   390

}

   391

   392

float PhysicsObject::getAim() {

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    return this->aim;

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}

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   396

std::vector<Vector>& PhysicsObject::getShape () {

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    return this->shape;

   398

}

   399

   400

void PhysicsObject::setShape (std::vector<Vector> shape) {

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    this->shape = shape;

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}

   403

   404

void PhysicsObject::tick () {

   405

    this->updatePosition();

   406

}

   407

   408

/**

   409

 * simple random map generation

   410

 * first fills whole level with dirt

   411

 * then randomizes circles of empty or rock

   412

 * @param seed - seed number for random number generator

   413

 */

   414

void PhysicsWorld::generateTerrain(int seed) {

   415

    // generating should use own random number generator, but didn't find easily how that is done

   416

    srand(seed);

   417

   418

    // some constants to control random generation

   419

    const int min_range = 25;

   420

    const int max_range = 80;

   421

    const int num = 50;

   422

    const int rock_rarity = 4; // 1 / rock_rarity will be rock circle

   423

   424

    // loops for amount of circles

   425

    for(int i = 0; i < num; i++) {

   426

        // information of new circle

   427

        int midx = rand()%(int)dimensions.x;

   428

        int midy = rand()%(int)dimensions.y;

   429

        int range = rand()%(max_range-min_range)+min_range;

   430

   431

        // put first circle in the middle of the cave

   432

        // so that we have some area we can certainly spawn into 

   433

        if(i == 0) {

   434

            midx = dimensions.x/2;

   435

            midy = dimensions.y/2;

   436

            range = 150;

   437

        }

   438

   439

        TerrainType type = EMPTY;

   440

        if(rand()%rock_rarity == 0) {

   441

            type = ROCK;

   442

        }

   443

   444

        // loops for every pixel of circle

   445

        for(int x = std::max(0, midx-range); x < std::min((int)dimensions.x, midx+range); x++) {

   446

            for(int y = std::max(0, midy-range); y < std::min((int)dimensions.y, midy+range); y++) {

   447

                //if((x-midx) * (x-midx) + (y-midy) * (y-midy) < range*range) {

   448

                // and sets it to type

   449

                terrain[x][y] = type;

   450

                //}

   451

            }

   452

        }

   453

    }

   454

}

   455

   456

/**

   457

 * Returns terrainType in given tile. ROCK if tile is out of area

   458

 * @param pos - coordinate of tile

   459

 */

   460

TerrainType PhysicsWorld::getType(int x, int y) const {

   461

    if(x < 0 || y < 0 || x >= dimensions.x || y >= dimensions.y) {

   462

        return ROCK;

   463

    }

   464

    return terrain[x][y];

   465

}

   466

TerrainType PhysicsWorld::getType(Vector pos) const {

   467

    int x = (int)(pos.x);

   468

    int y = (int)(pos.y);

   469

    return getType(x, y);

   470

}

   471

   472

/**

   473

 * Removes ground from given circle. ROCK is not removed.

   474

 * @param (x, y) or pos - center of circle.

   475

 * @param r - radius of circle

   476

 */

   477

void PhysicsWorld::removeGround(int x, int y, float r) {

   478

    for(int i = x-(int)r; i < x+r; i++) {

   479

        for(int j = y-(int)r; j < y+r; j++) {

   480

            if(getType(i, j) != ROCK) {

   481

                if((i-x)*(i-x)+(j-y)*(j-y) < r*r) {

   482

                    // Safe because getType returns ROCK if tile is out of bounds

   483

                    terrain[i][j] = EMPTY;

   484

                }

   485

            }

   486

        }

   487