PixelDefense/engine/breeze/ai/behaviour_tree.h

#ifndef BREEZE_BEHAVIOUR_TREE_H
#define BREEZE_BEHAVIOUR_TREE_H

#include "../defines.h"

typedef struct BzBTNode BzBTNode;

typedef enum BzBTStatus {
    BZ_BT_RUNNING,
    BZ_BT_SUCCESS,
    BZ_BT_FAIL,
    BZ_BT_ERROR,
} BzBTStatus;

typedef BzBTStatus(*BzBTActionFn)(void *data, f32 dt);

typedef enum BzBTNodeType {
    // Composite
    BZ_BT_COMP_SELECTOR,
    BZ_BT_COMP_SEQUENCE,
    BZ_BT_COMP_PSELECTOR,
    BZ_BT_COMP_PSEQUENCE,
    // Decorator
    BZ_BT_DECOR_DUMMY,
    BZ_BT_DECOR_SUCCESS,
    BZ_BT_DECOR_FAIL,
    BZ_BT_DECOR_INVERT,
    BZ_BT_DECOR_UNTIL_SUCCESS,
    BZ_BT_DECOR_UNTIL_FAIL,
    BZ_BT_DECOR_REPEAT,
    BZ_BT_DECOR_DELAY,
    // Action/Task
    BZ_BT_ACTION,
} BzBTNodeType;

typedef struct BzObjectPool BzObjectPool;
typedef struct BzBTNodeState BzBTNodeState;

typedef struct BzBTState {
    const BzBTNode *root;
    BzBTNodeState  *_first;
    BzBTNodeState  *_last;

    BzBTActionFn onSuccess;
    BzBTActionFn onFailure;
    BzBTActionFn onError;

    BzObjectPool *nodeStatePool;
    void *userData;
} BzBTState;

typedef struct BzBTStateDesc {
    const BzBTNode *root;

    BzObjectPool *pool;
    void *userData;
} BzBTStateDesc;

/**
 * @brief Useful for allocating BzBTNode pools.
 * @return size of BzBTNode
 */
size_t  bzBTGetNodeSize();
/**
 * @brief Useful for allocating BzBTNodeState pools.
 * @return size of BzBTNodeState
 */
size_t  bzBTGetNodeStateSize();

/**
 * @brief Utility function for converting enum type to human readable string.
 * @return human-readable node type
 */
const char *bzBTNodeTypeToStr(BzBTNodeType type);

/**
 * @brief Starting point of BT.
 * @param nodePool pool
 * @return allocated node
 */
BzBTNode *bzBTMakeRoot(BzObjectPool *nodePool);
/**
 * @brief Recursively cleans up BT.
 * @param nodePool pool
 * @param node BT root
 */
void bzBTDestroyRoot(BzObjectPool *nodePool, BzBTNode *node);

/**
 * @brief Execute all children in turn until one fails.
 *
 * Execution is BZ_BT_SUCCESS, if all children are ran successfully.
 * Child execution, does not progress unless child finishes (no BZ_BT_RUNNING status).
 *
 * @param nodePool pool
 * @param parent parent of the composite
 * @return allocated composite
 */
BzBTNode *bzBTCompSelector(BzObjectPool *nodePool, BzBTNode *parent);
/**
 * @brief Execute all children in turn until first one succeeds.
 *
 * Execution is BZ_BT_FAIL, if no children are ran successfully.
 * Child execution is blocking -> it does not progress unless child
 * finishes (is not BZ_BT_RUNNING).
 *
 * @param nodePool pool
 * @param parent parent of the composite
 * @return allocated composite
 */
BzBTNode *bzBTCompSequence(BzObjectPool *nodePool, BzBTNode *parent);

/**
 * @brief Execute all children in turn until one fails.
 *
 * Execution is BZ_BT_SUCCESS, if all children are ran successfully.
 * Children are executed in non-blocking way in the order of BT.
 *
 * @param nodePool pool
 * @param parent parent of the composite
 * @return allocated composite
 */
BzBTNode *bzBTCompPSelector(BzObjectPool *nodePool, BzBTNode *parent);
/**
 * @brief Execute all children in turn until first one succeeds.
 *
 * Execution is BZ_BT_FAIL, if no children are ran successfully.
 * Children are executed in non-blocking way in the order of BT.
 *
 * @param nodePool pool
 * @param parent parent of the composite
 * @return allocated composite
 */
BzBTNode *bzBTCompPSequence(BzObjectPool *nodePool, BzBTNode *parent);

/**
 * @brief Returns child status.
 *
 * Note: Useful when nesting BTs.
 *
 * @param nodePool pool
 * @param parent parent of the decorator
 * @return allocated decorator
 */
BzBTNode *bzBTDecorDummy(BzObjectPool *nodePool, BzBTNode *parent);
/**
 * @brief Returns BZ_BT_SUCCESS, if no BZ_BT_ERROR occurred.
 * @param nodePool pool
 * @param parent parent of the decorator
 * @return allocated decorator
 */
BzBTNode *bzBTDecorSuccess(BzObjectPool *nodePool, BzBTNode *parent);
/**
 * @brief Returns BZ_BT_FAIL, if no BZ_BT_ERROR occurred.
 * @param nodePool pool
 * @param parent parent of the decorator
 * @return allocated decorator
 */
BzBTNode *bzBTDecorFail(BzObjectPool *nodePool, BzBTNode *parent);
/**
 * @brief Inverts child result.
 *
 * Note: Only for BZ_BT_SUCCESS and BZ_BT_FAIL. Other statuses
 * are propagated up.
 *
 * @param nodePool pool
 * @param parent parent of the decorator
 * @return allocated decorator
 */
BzBTNode *bzBTDecorInvert(BzObjectPool *nodePool, BzBTNode *parent);
/**
 * @brief Repeats child execution until it returns BZ_BT_SUCCESS.
 *
 * Note: BZ_BT_ERROR also causes it to return.
 *
 * @param nodePool pool
 * @param parent parent of the decorator
 * @return allocated decorator
 */
BzBTNode *bzBTDecorUntilSuccess(BzObjectPool *nodePool, BzBTNode *parent);
/**
 * @brief Repeats child execution until it returns BZ_BT_FAIL.
 *
 * Note: BZ_BT_ERROR also causes it to return.
 *
 * @param nodePool pool
 * @param parent parent of the decorator
 * @return allocated decorator
 */
BzBTNode *bzBTDecorUntilFail(BzObjectPool *nodePool, BzBTNode *parent);
/**
 * @brief Repeats child execution n-times.
 * @param nodePool pool
 * @param parent parent of the decorator
 * @param n number of repeats
 * @return allocated decorator
 */
BzBTNode *bzBTDecorRepeat(BzObjectPool *nodePool, BzBTNode *parent, i32 n);
/**
 * @brief Delays child/sibling execution for specified ms.
 *
 * Note: for this to properly work, correct dt must be passed
 * in when executing BT.
 *
 * @param nodePool pool
 * @param parent parent of the decorator
 * @param ms milliseconds to wait
 * @return allocated decorator
 */
BzBTNode *bzBTDecorDelay(BzObjectPool *nodePool, BzBTNode *parent, f32 ms);

/**
 * @brief Creates BT task.
 * @param nodePool pool
 * @param parent parent of the task
 * @param fn function pointer for the task
 * @return allocated action
 */
BzBTNode *bzBTAction(BzObjectPool *nodePool, BzBTNode *parent, BzBTActionFn fn);

// Reflection data

void bzBTNodeSetName(BzBTNode *node, const char *name);
const char *bzBTNodeGetName(const BzBTNode *node);

i32 bzBTDecorGetRepeat(const BzBTNode *node);
f32 bzBTDecorGetDelay(const BzBTNode *node);

BzBTActionFn bzBTActionGetFn(const BzBTNode *node);

BzBTNodeType bzBTGetNodeType(const BzBTNode *node);
BzBTNode *bzBTNodeChild(const BzBTNode *node);
BzBTNode *bzBTNodeNext(const BzBTNode *node);

const BzBTNode *bzBTNodeStateGetNode(const BzBTNodeState *state);

const BzBTNodeState *bzBTNodeStateNext(const BzBTNodeState *state);
bool bzBTNodeMatchesState(const BzBTNode *node, const BzBTNodeState *state);

BzBTNode *bzBTCompStateGetRunningChild(const BzBTNodeState *state);

i32 bzBTRepeatStateGetIter(const BzBTNodeState *state);
f32 bzBTDelayStateGetElapsed(const BzBTNodeState *state);

/**
 * @brief Creates state for a given BT.
 * @param desc input parameters
 * @return BT state
 */
BzBTState bzBTCreateState(const BzBTStateDesc *desc);
/**
 * @brief Cleans up state (does not modify BT).
 * @param state state to clean up
 */
void bzBTDestroyState(BzBTState *state);

/**
 * @brief Tick behaviour tree.
 * @param state state of the behaviour tree
 * @param dt delta time
 * @return status of BT tick
 */
BzBTStatus bzBTExecute(BzBTState *state, f32 dt);

#endif //BREEZE_BEHAVIOUR_TREE_H