#pragma once

/**
 * This function must be called before any other 'resources_*' function.
 * 
 * It may initialize data, but may as well be empty. It's up to you.
 */
void resources_init();

/**
 * Registers new kind of resource, and sets the number of items of this kind.
 * 
 * The function returns:
 *   • 0 on success
 *   • 1 if 'kind' is negative or 'availableCount' is nonpositive
 *   • 2 if resource of the provided 'kind' has already been created
 */
int resources_create(int kind, int availableCount);

/**
 * Takes resources according to specification. The 'what' argument is an array
 * of 'resources_request' structures, of length 'arrayLength'. Each element of
 * the array specifies a resource kind and the number of items to take.
 * 
 * This function waits until the resources become available.
 * 
 * Assigning resources must be done in first come - first served (first in -
 * first out) manner. That is, when a thread t₂ asked for the resources later
 * than t₁, then t₁ must not wait longer because of t₂ getting the resources
 * first. Notice that if it is possible to give resources to t₂ without causing
 * t₁ to wait longer, this has to be done.
 * 
 * A thread must not request resources it it still has some resources it did
 * not return.
 * 
 * The function returns:
 *   • 0 on success
 *   • 1 if array length is negative
 *   • 2 if the array has the same kind of resources on two indexes
 *   • 3 if the thread did not return some resourced that it took earlier
 *   • 4 if the thread requested a resource kind that was not yet created
 *   • 5 if the thread requested more resources of some kind than there exist
 */ 
struct resources_request {
    int kind;
    int count;
};
int resources_take(int arrayLength, struct resources_request *what);

/**
 * Returns a resource that was taken by the thread earlier on.
 * 
 * The resources can be returned in arbitrary order.
 * 
 * If multiple resources of the the same kind were taken, they may be returned
 * in portions.
 * 
 * The function returns:
 *   • 0 on success
 *   • 1 if the kind of resource does not exist
 *   • 2 if the thread did not take the resource it attempts to return
 *   • 3 if the thread attempts to return more resources than it took
 */
int resources_return(int kind, int count);