#include "Physics.hh"
#include "Engine.hh"
#include "GameState.hh"

#include <algorithm>
#include <functional>
#include <cmath>
#include <assert.h>

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

    generateTerrain(1337);

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

void PhysicsWorld::addObject (PhysicsObject *object) {
    objects.push_back(object);
}

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

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

    tick_counter++;
}

uint32_t PhysicsWorld::getTick (void) {
    return tick_counter;
}

PhysicsObject::PhysicsObject (PhysicsWorld &world, float mass, 
                              Vector position, Vector velocity)
    : world(world), mass(mass), position(position), 
      velocity(velocity), facingRight(true), inAir(true) {

    world.addObject(this);
}

Vector PhysicsObject::walk (bool right) {
    Vector cursor = right ? this->position + Vector(1,0) : this->position + Vector(-1,0);
    Vector reached = this->position;
    
    //for(int steps = 0; steps < 3; steps++) {
    
    // Go up but not if the wall is over two pixels
    if(world.getType(cursor) != EMPTY) {
        for(int height = 0, max = 3; height < max+42; height++) {
            
            if(height >= max)
                return reached;
            
            cursor.y--;
            if(world.getType(cursor) == EMPTY) {
                // Check that the other parts of the worm don't collide with anything
                if(possibleLocation(cursor)) {
                    reached = cursor;
                    continue;
                } else {
                    // Can't get any further
                    return reached;
                }
            }
        }
    } else {
        if(possibleLocation(cursor)) {
            reached = cursor;
        }
        // Start checking if the lower squares are empty
        
        for(int depth = 0, max = 3; depth < max+42; depth++) {
            
            if(depth >= max) {
                // We can start a free fall now
                //
                // TODO it should be set inAir if it falls from a cliff
                this->inAir = true;
                
                // Put some speed there to make loke smoother
                //this->velocity.y = -5;
                return reached;
            }
            
            cursor.y++;
            if(world.getType(cursor) == EMPTY) {
                // Check that the other parts of the worm don't collide with anything
                if(possibleLocation(cursor)) {
                    reached = cursor;
                    continue;
                } else {
                    // Can't get any further
                    return reached;
                }
            }
        }
    }      
    
    //    cursor.x += right ? 1 : -1;
    //}
    return reached;
}

void PhysicsObject::jump () {
    // Jump only if player is "on the ground"
    if (!this->inAir) {
 	velocity.y = -100;
	inAir = true;
    }
}

bool PhysicsObject::possibleLocation (Vector loc) {
    for(unsigned int i = 0; i < this->shape.size(); i++) {
        if(world.getType(loc+shape[i]) != EMPTY)
            return false;
    }
    return true;
}

/**
 * Updates object speed and position. This function organises force
 * integration and collision detection.
 */   
void PhysicsObject::updatePosition () {

    // Add gravity to the force queue
    forceq.push(world.gravity);
    
    // Go trough every force in the queue
    Force total;
    posAfterTick = position;
    velAfterTick = velocity;
    while (!forceq.empty()) {
        total += forceq.front();
        forceq.pop();
    }

    // TODO: This is _ugly_ (but not so ugly as the last one I think)
    // hack. I think we should handle walking from the collision
    // detection code.

    if (!this->inAir) {
        if (total.x != 0)
            this->position = walk(total.x > 0);
        return; // argh
    }

    integrate(total, PHYSICS_TICK_MS);

    Vector newPosition = posAfterTick /*+ (velAfterTick * PHYSICS_TICK_MS)/1000*/;
    this->velocity = velAfterTick;

   
    // Collision detection
    bool collided = false;
   
    const Vector diffVec = newPosition-position;
    const Vector unitVector = diffVec / diffVec.length();
    Vector reached = position;

    while ((position-reached).length() < diffVec.length()) {
        // Check if any of the shapes points collide
        for (uint64_t i = 0; i < shape.size(); i ++) {
            if (world.getType(reached+shape[i]) != EMPTY) {  // Collision
                this->bounce(world.getNormal(reached+shape[i], reached-unitVector+shape[i]));
                reached = reached - unitVector; // Return to last point
                collided = true;
                this->velocity *= COLLISION_ELASTICITY;
                if (this->velocity.length() < PLAYER_MIN_SPEED) {
                    this->inAir = false;
                    this->velocity = Vector(0,0);
                }
                break;
            }
        }
        if (collided)
            break;
        reached += unitVector;
    }
   
    
    /*
      bool collided = false;

      //goes 1 unit forward every step and check if has hit anything
      Vector unitVector = (newPosition-position) / (newPosition-position).length();
    
      Vector tmpVector = position;
      Vector reached = position;

      int steps = (int) (newPosition-position).length() + 2;
        
      //Engine::log(DEBUG, "physics.update_position") << unitVector-newPosition;
      //Vector foo = position+unitVector*steps-newPosition;
      //Engine::log(DEBUG, "PhysicsObject.updatePosition") << "Virhe: "<< foo;
    
      for(int i = 0; i < steps; i++) {
      tmpVector += unitVector;

      float minVelocity = 10;
      // Check if any of the four corners of the worm collide
      for(int sh = 0; sh < 4; sh++) {
      if(world.getType(tmpVector+shape[sh]) != EMPTY) {
      reached = position + unitVector*(i-1);
      collided = true;
      this->bounce(world.getNormal(tmpVector+shape[sh], tmpVector-unitVector+shape[sh]));
      this->velocity *= 0.4;
      if(abs(this->velocity.x) < minVelocity && (abs(this->velocity.y) < minVelocity)) {
      this->inAir = false;
      this->velocity = Vector(0,0);
      }
      break;
      }
      }
      if(collided)
      break;
      }
    */

    // In case of some float error check the final coordinate
    if(!collided) {
        if(world.getType(newPosition+shape[0]) != EMPTY || (world.getType(newPosition+shape[1]) != EMPTY) 
           || (world.getType(newPosition+shape[2]) != EMPTY) || (world.getType(newPosition+shape[3]) != EMPTY)) {
            
            Engine::log(DEBUG, "physics.update_position") << "didnt hit";
            // There was error, and there is ground
            //newPosition = tmpVector;
        } else {
            // This means everything was ok, so no need to do anything
        }
    } else {
        newPosition = reached;
        onCollision();
        //this->velocity = Vector(0, 0);
        //TODO: it shouldn't just stop on collision
    }
    this->position = newPosition;
    
}

/**
 * Gets the index of the given coordinate direction
 * referring to the DIRECTIONS table in Physics.hh
 */
int getDirectionIndex (Vector dir) {
    if(dir.x == 0 && dir.y == -1) {
        return 0;
    } else if(dir.x == 1 && dir.y == -1) {
        return 1;
    } else if(dir.x == 1 && dir.y == 0) {
        return 2;
    } else if(dir.x == 1 && dir.y == 1) {
        return 3;
    } else if(dir.x == 0 && dir.y == 1) {
        return 4;
    } else if(dir.x == -1 && dir.y == 1) {
        return 5;
    } else if(dir.x == -1 && dir.y == 0) {
        return 6;
    } else if(dir.x == -1 && dir.y == -1) {
        return 7;
    }
    Engine::log(DEBUG, "physics.getDirectionIndex ") << "invalid direction: " << dir;
    return 0;
}

/**
 * Computes hitten wall's normal. Calculated from 3*3 grid
 */
Vector PhysicsWorld::getNormal (Vector hitPoint, Vector prevPoint) {
    // Search free points with bfs and put them to vector
    std::vector<Vector> frees;
    Vector hit(hitPoint);
    Vector prev(prevPoint);

    assert(hit != prev);
    
    int dirIdx = getDirectionIndex(prev.roundToInt() - hit.roundToInt());
    //float tmp1 = hit.x-prev.x;
    //float tmp2 = hit.y-prev.y;
    //    Engine::log(DEBUG, "physics.getNormal ") << dirIdx << " " << tmp1 << " " << tmp2;

    for(int i = 1; i <= 2; i++) {
        if(getType(hit+DIRECTIONS[(dirIdx+i) % 8]) == EMPTY)
            frees.push_back(DIRECTIONS[(dirIdx+i) % 8]);
        else 
            break;
    }
    for(int i = 1; i <= 2; i++) {
        if(getType(hit+DIRECTIONS[(dirIdx-i+8) % 8]) == EMPTY)
            frees.push_back(DIRECTIONS[(dirIdx-i+8) % 8]);
        else
            break;
    }
    frees.push_back(DIRECTIONS[dirIdx]);

    Vector normal(0,0);
    for(unsigned int i = 0; i < frees.size(); i++) {
        normal += frees[i];
    }
    Engine::log(DEBUG, "physics.getNormal ") << "normal: " << normal;
    return normal;
}

/**
 * Bounces from straight wall in any direction.
 * Direction given as normal of that wall
 */
// TODO Bounce doesnt work kun oikealle tai vasemmalle alaviistoon mennään suoralla (tangentaalinen arvo väärän suuntainen)
void PhysicsObject::bounce (Vector normal) {
    Vector tangent(normal.y, -normal.x);
    Vector tprojection = tangent*(velocity * tangent) / (tangent.length()*tangent.length());
    Vector nprojection = normal*(velocity * normal) / (normal.length()*normal.length());
    velocity = tprojection - nprojection;
}

/*bool PhysicsWorld::collided (Vector oldPos, Vector newPos) {
  return false;
  }*/

/**
 * Integrates given force over time and stores new position to
 * posAfterTick and new velocity to velAfterTick.
 * @param force Force vector.
 * @param dt The time the force is applied (<=PHYSICS_TICK_MS)
 */
void PhysicsObject::integrate(Force force, TimeMS dt) {
    Derivative tmpd;
    Derivative k1 = evaluate(force, 0, tmpd);
    Derivative k2 = evaluate(force, 0.5f*dt, k1);
    Derivative k3 = evaluate(force, 0.5f*dt, k2);
    Derivative k4 = evaluate(force, dt, k3);
    

    const Vector dxdt = (k1.dx + (k2.dx + k3.dx) * 2.0f + k4.dx) * 1.0f/6.0f;
    const Vector dvdt = (k1.dv + (k2.dv + k3.dv) * 2.0f + k4.dv) * 1.0f/6.0f;
    
    //    Engine::log(DEBUG, "PhysicsObject.integrate") << "Changes: "<< dxdt << " " << dvdt << " Time: " <<dt;
    posAfterTick = posAfterTick + (dxdt * dt)/1000;
    velAfterTick = velAfterTick + (dvdt * dt)/1000;
    //Engine::log(DEBUG, "PhysicsObject.integrate") << "velAfterTick: " << velAfterTick;
}

Derivative PhysicsObject::evaluate(Force force, TimeMS dt, Derivative &d) {
    Vector curPos = posAfterTick + (d.dx*dt)/1000;
    Vector curVel = velAfterTick + (d.dv*dt)/1000;

    Derivative out;
    out.dx = curVel;
    out.dv = acceleration(force);
    //Engine::log(DEBUG, "PhysicsObject.evaluate") << "Out.dx: " << out.dx;
    return out;
}

Vector PhysicsObject::acceleration(const Force &force) {
    return (force/mass);
}

void PhysicsObject::applyForce (Force force) {
    // Add applied force to the queue
    forceq.push(force);
}

void PhysicsObject::changeAim(float da) {
    this->aim += da;

    if (this->aim > PLAYER_AIM_MAX) this->aim = PLAYER_AIM_MAX;
    if (this->aim < PLAYER_AIM_MIN) this->aim = PLAYER_AIM_MIN;
    //Engine::log(DEBUG, "PhysicsObject.changeAim") << "Player aim: " << this->aim;
}

void PhysicsObject::setFacing(bool facingRight) {
    //Engine::log(DEBUG, "PhysicsObject.setFacing") << "Facing: " << right;
    this->facingRight = facingRight;
}

void PhysicsObject::updatePhysics (Vector position, Vector velocity, bool inAir) {
    this->position = position;
    this->velocity = velocity;
    this->inAir = inAir;
}
    
Vector PhysicsObject::getPosition () {
    return this->position;
}

bool PhysicsObject::getFacing() {
    return this->facingRight;
}

float PhysicsObject::getAim() {
    return this->aim;
}

std::vector<Vector>& PhysicsObject::getShape () {
    return this->shape;
}

void PhysicsObject::setShape (std::vector<Vector> shape) {
    this->shape = shape;
}

void PhysicsObject::tick () {
    this->updatePosition();
}

/**
 * simple random map generation
 * first fills whole level with dirt
 * then randomizes circles of empty or rock
 * @param seed - seed number for random number generator
 */
void PhysicsWorld::generateTerrain(int seed) {
    // generating should use own random number generator, but didn't find easily how that is done
    srand(seed);
    
    // some constants to control random generation
    const int min_range = 25;
    const int max_range = 80;
    const int num = 50;
    const int rock_rarity = 4; // 1 / rock_rarity will be rock circle

    // loops for amount of circles
    for(int i = 0; i < num; i++) {
        // information of new circle
        int midx = rand()%(int)dimensions.x;
        int midy = rand()%(int)dimensions.y;
        int range = rand()%(max_range-min_range)+min_range;

        // put first circle in the middle of the cave
        // so that we have some area we can certainly spawn into 
        if(i == 0) {
            midx = dimensions.x/2;
            midy = dimensions.y/2;
            range = 150;
        }

        TerrainType type = EMPTY;
        if(rand()%rock_rarity == 0) {
            type = ROCK;
        }

        // loops for every pixel of circle
        for(int x = std::max(0, midx-range); x < std::min((int)dimensions.x, midx+range); x++) {
            for(int y = std::max(0, midy-range); y < std::min((int)dimensions.y, midy+range); y++) {
                //if((x-midx) * (x-midx) + (y-midy) * (y-midy) < range*range) {
                // and sets it to type
                terrain[x][y] = type;
                //}
            }
        }
    }
}

/**
 * Returns terrainType in given tile. ROCK if tile is out of area
 * @param pos - coordinate of tile
 */
TerrainType PhysicsWorld::getType(int x, int y) const {
    if(x < 0 || y < 0 || x >= dimensions.x || y >= dimensions.y) {
        return ROCK;
    }
    return terrain[x][y];
}
TerrainType PhysicsWorld::getType(Vector pos) const {
    int x = (int)(pos.x);
    int y = (int)(pos.y);
    return getType(x, y);
}

/**
 * Removes ground from given circle. ROCK is not removed.
 * @param (x, y) or pos - center of circle.
 * @param r - radius of circle
 */
void PhysicsWorld::removeGround(int x, int y, float r) {
    for(int i = x-(int)r; i < x+r; i++) {
        for(int j = y-(int)r; j < y+r; j++) {
            if(getType(i, j) != ROCK) {
                if((i-x)*(i-x)+(j-y)*(j-y) < r*r) {
                    // Safe because getType returns ROCK if tile is out of bounds
                    terrain[i][j] = EMPTY;
                }
            }
        }
    }
}
void PhysicsWorld::removeGround(Vector pos, float r) {
    removeGround((int)pos.x, (int)pos.y, r);
}