#ifndef REGISTRY_H
#define REGISTRY_H

#include "oo.qh"

#define REGISTER_INIT(ns, id) [[accumulate]] void Register_##ns##_##id##_init(entity this)
#define REGISTER_INIT_POST(ns, id) [[accumulate]] void Register_##ns##_##id##_init_post(entity this)

/**
 * Register a new entity with a global constructor.
 * Must be followed by a semicolon or a function body with a `this` parameter.
 * Wrapper macros may perform actions after user initialization like so:
 *     #define REGISTER_FOO(id) \
 *         REGISTER(RegisterFoos, FOO, FOOS, FOOS_COUNT, id, m_id, NEW(Foo)); \
 *         REGISTER_INIT_POST(FOO, id) { \
 *             print("Registering foo #", this.m_id + 1, "\n"); \
 *         } \
 *         REGISTER_INIT(FOO, id)
 *
 * Don't forget to forward declare `initfunc` and call `REGISTER_REGISTRY`:
 *     void RegisterFoos();
 *     REGISTER_REGISTRY(RegisterFoos)
 *
 * @param initfunc  The global constructor to accumulate into
 * @param ns        Short for namespace, prefix for each global (ns##_##id)
 * @param array     The array to add each entity to. Also requires `array##_first` and `array##_last` to be defined
 * @param counter   Global to count number of entries
 * @param id        The identifier of the current entity being registered
 * @param fld       The field to store the current count into
 * @param inst      An expression to create a new instance, invoked for every registration
 */
#define REGISTER(initfunc, ns, array, counter, id, fld, inst)   \
    entity ns##_##id;                                           \
    REGISTER_INIT(ns, id) { }                                   \
    REGISTER_INIT_POST(ns, id) { }                              \
    .entity enemy; /* internal next pointer */                  \
    void Register_##ns##_##id() {                               \
        entity this = inst;                                     \
        ns##_##id = this;                                       \
        this.fld = counter;                                     \
        array[counter++] = this;                                \
        if (!array##_first)    array##_first = this;            \
        if ( array##_last)     array##_last.enemy = this;       \
        array##_last = this;                                    \
        Register_##ns##_##id##_init(this);                      \
        Register_##ns##_##id##_init_post(this);                 \
    }                                                           \
    ACCUMULATE_FUNCTION(initfunc, Register_##ns##_##id)         \
    REGISTER_INIT(ns, id)

#endif