entity.h

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#ifndef __ENTITY__H
#define __ENTITY__H

#include "globals.h"
#include "graphics.h"
#include "ai_interpret.h"

#define MAX_ENTITIES 250
#define ENTITY_DIR_LEFT 0
#define ENTITY_DIR_RIGHT 1

typedef struct entity_s entity_t;
struct power_s;
/**
 * The core structure of our our entity system.
 *
 * @author      Anthony Rios
 * @date        2/17/2016
 */

struct entity_s
{
        int mHazards;                                   /**< The hazards that the entity is immune to / deals*/
        int mNextThink;                                 /**< The next time the entity should think */
        int mHealth;                                    /**< The health of the entity, if below zero - destroy this entity*/
        int mDamage;                                    /**< The damage the entity should deal to other entities */
        int mWeight;                                    /**< The weight boolean of the entity, if gravity affects him*/
        int mCurrentFrame;                              /**< The current frame */
        int mDirection:1;                               /**< The direction entity is facing*/
        collision_type_t mCollisionType;        /**< Type of the collision the entity is */
        entity_state_t mEntityState;    /**< The state of the entity */
        sprite_t **mSprites;                    /**< The sprites of the given entity */
        sprite_t *mAnimation;                   /**< The current animation, the entity is running */
        ai_function_t *mData;                   /**< The data that an entity stores for its ai */
        char *mName;                                    /**< The name of the entity*/
        vec2_t mAccel;                                  /**< The acceleration vector */
        vec2_t mVelocity;                               /**< The velocity vector */
        vec2_t mPosition;                               /**< The position vector, equal to on screen draw position */
        void (*Think)(entity_t *self);  /**< The think function which gets called to update the entity*/
        void (*Touch)(entity_t *self, entity_t *other, int type);       /**< The function that gets called when enitities collide*/
        void (*Draw)(entity_t *self);   /**< The function that gets called every frame to draw the entity*/
        void (*PowerUp)(struct power_s *info);  /**< The player specific function for power_up useage */
};

extern entity_t *gEntityDictionary;     /**< Entities loaded from files AKA cached entities */
extern entity_t *gEntities;                     /**< The memory for entities that are currently running in the game */
extern int gLastEntity;                         /**< The last entity that was free'd or created */

/**
 * Init entity system.
 *
 * @return      An int of failure state. 0 if good, -1 if error.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
extern int InitEntitySystem();

/**
 * Init new entity in the memory of global entity space.
 *
 * @return      null if it fails, else a pointer to an entity_t.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
extern entity_t *InitNewEntity();

/**
 * Searches for the next free cache position in gEntitiesDictionary.
 *
 * @return      null if it fails, else the found free cache position.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
extern entity_t *FindNextFreeCachePos();

/**
 * Searches for the cached entity whose name matches given str.
 *
 * @param       name    The name of the entity.
 *
 * @return      null if it fails, else the found cached entity.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
extern entity_t *FindCachedEntity(const char *name);

/**
 * Searches for the first entity with the name of given str.
 *
 * @param       name    The name of the searched for entity.
 *
 * @return      null if it fails, else the found entity.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
extern entity_t *FindEntity(const char *name);

/**
 * Searches for the first free entity.
 *
 * @param [in,out]      position        If non-null, the position.
 *
 * @return      null if it fails, else the found free entity.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
extern entity_t *FindFreeEntity(int* position);

/**
 * Look for entity at position.
 *
 * @param       position        The position.
 *
 * @return      null if it fails, else a pointer to an entity_t.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
extern entity_t *LookForEntityAtPos(vec2_t position);

/**
 * Distance 2 entity other from entity self.
 *
 * @param [in,out]      self    If non-null, the class instance that this method operates on.
 * @param [in,out]      other   If non-null, the other entity.
 *
 * @return      An int.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
extern int Distance2Entity(entity_t *self, entity_t *other);

/**
 * Returns a function pointer to the think function, given ai_function data.
 *
 * @param [in,out]      parameter1      If non-null, the first parameter.
 *
 * @return      null if it fails, else a GetFunctionAI(ai_function_t *data.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
extern void (*GetFunctionAI(ai_function_t *data))(entity_t *);

/**
 * Executes the entities think functions.
 *
 * @note        I think I have the logic wrong..
 * @author      Anthony Rios
 * @date        3/29/2016
 */
void RunEntities();

/**
 * Draw entities, if they have draw functions.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
void DrawEntities();

/**
 * Prints the entities data, used for debug.
 *
 * @param [in,out]      ent     If non-null, the ent.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
extern void PrintEntity(entity_t *ent);

/**
 * Free entity.
 * 
 * @note        right now it just acts like memset(0) on entities in the global Entities scope.
 *                      But it free's any other data that isn't globally set.
 *
 * @param [in,out]      ent     If non-null, the ent.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
void FreeEntity(entity_t *ent);

/**
 * Frees the non player entities, use for Destroy World.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
void FreeNonPlayerEntities();

/**
 * Shutdown entity system, frees all the entities.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
void ShutdownEntitySystem();

//Draw Functions
/**
 * Draws the entity via self->mAnimation if set, or the first sprite which is idle.
 *
 * @param [in,out]      self    If non-null, the class instance that this method operates on.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
void DrawGeneric(entity_t *self);
//Unused for now
void DrawPlayer(entity_t *self);

//Think Functions
/**
 * Generic think function, checks health and dies when health <= 0
 *
 * @param [in,out]      self    If non-null, the class instance that this method operates on.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
void ThinkGeneric(entity_t *self);

/**
 * The player think function, handles lives ,gamestate switching , and input.
 *
 * @param [in,out]      self    If non-null, the class instance that this method operates on.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
void ThinkPlayer(entity_t *self);

/**
 * The modular think function for enemy entities with an AI.
 *
 * @param [in,out]      self    If non-null, the class instance that this method operates on.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
void ThinkEnemy(entity_t *self);

/**
 * Generic touch function,
 * Receives pain from touch and inflict pain on touch depending on hazard types.
 *
 * @param [in,out]      self    If non-null, the class instance that this method operates on.
 * @param [in,out]      other   If non-null, the other.
 * @param       type                    The type.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
void TouchGeneric(entity_t *self, entity_t *other, int type);

/**
 * The player touch function called on collision.
 * If he touches a hazard, he gets damaged.
 *
 * @param [in,out]      self    If non-null, the class instance that this method operates on.
 * @param [in,out]      other   If non-null, the other.
 * @param       type                    The type.
 *
 * @author      Anthony Rios
 * @date        3/30/2016
 */
void TouchPlayer(entity_t *self, entity_t *other, int type);

/**
 * The touch function for an enemy, currently does nothing.
 *
 * @param [in,out]      self    If non-null, the class instance that this method operates on.
 * @param [in,out]      other   If non-null, the other.
 * @param       type                    The type.
 *
 * @author      Anthony Rios
 * @date        3/30/2016
 */

void TouchEnemy(entity_t *self, entity_t *other, int type);

/**
 * The touch function for the goal entity / flag.
 * Switches gamestate based on if you won or should go to the next level.
 *
 * @param [in,out]      self    If non-null, the class instance that this method operates on.
 * @param [in,out]      other   If non-null, the other entity it touched.
 * @param       type                    The type.
 *
 * @author      Anthony Rios
 * @date        3/29/2016
 */
void TouchGoal(entity_t *self, entity_t *other, int type);


#endif