// A purely global, all macro-driven ecs implementation.
// You are expected to have only a need for a global
// ecs when using this.
#ifndef __HALOO3D_ECS2_H
#define __HALOO3D_ECS2_H

#include <stdint.h>

#ifndef ECS_MAXENTITIES
#define ECS_MAXENTITIES 1024
#endif

#define ECS_MAXCTYPES 63 // uint64 bits minus one

typedef uint64_t ecs_cid;
typedef int ecs_eid;

#define ECS_START(name)                                                        \
  typedef struct {                                                             \
    ecs_cid entities[ECS_MAXENTITIES];                                         \
    ecs_eid entitytop;

#define ECS_END(name)                                                          \
  }                                                                            \
  name;                                                                        \
  static void name##_init(name *_ecs) { memset(_ecs, 0, sizeof(name)); }       \
  static ecs_eid name##_newentity(name *_ecs, ecs_cid basecomponents) {        \
    for (int i = 0; i < ECS_MAXENTITIES; i++) {                                \
      ecs_eid id = _ecs->entitytop++;                                          \
      if (_ecs->entities[id] == 0) {                                           \
        _ecs->entities[id] = (1ULL << ECS_MAXCTYPES) | basecomponents;         \
        return id;                                                             \
      }                                                                        \
    }                                                                          \
    return -1;                                                                 \
  }                                                                            \
  static void name##_deleteentity(name *_ecs, ecs_eid eid) {                   \
    if (eid >= 0 && eid < ECS_MAXENTITIES)                                     \
      _ecs->entities[eid] = 0;                                                 \
  }                                                                            \
  static int name##_match(name *_ecs, ecs_eid _eid, ecs_cid _comps) {          \
    ecs_cid _realcomps = (1ULL << ECS_MAXCTYPES) | _comps;                     \
    return (_ecs->entities[_eid] & _realcomps) == _realcomps;                  \
  }

#define ECS_COMPONENT(type) type c_##type[ECS_MAXENTITIES];

#define ECS_CID(type, id)                                                      \
  const int type##_id = id;                                                    \
  const ecs_cid type##_fl = (1ULL << id);

// Set the given entity to have the given component (by type). Follow this
// macro immediately with the struct initializer
#define ECS_SETCOMPONENT(_ecs, eid, type)                                      \
  (_ecs)->entities[eid] |= type##_fl;                                          \
  (_ecs)->c_##type[eid] = (type)

// Add a system function which automatically calls your given function with
// pre-pulled items from the entity component arrays. The new function is
// named the same as the old one, just with _run appeneded
#define ECS_SYSTEM1(ecsname, fname, type1)                                     \
  void fname##_run(ecsname *_ecs, ecs_eid eid) {                               \
    ecs_cid _ecsflags = type1##_fl;                                            \
    if (ecsname##_match(_ecs, eid, _ecsflags)) {                               \
      fname(_ecs->c_##type1 + eid);                                            \
    }                                                                          \
  }

#define ECS_SYSTEM2(ecsname, fname, type1, type2)                              \
  void fname##_run(ecsname *_ecs, ecs_eid eid) {                               \
    ecs_cid _ecsflags = type1##_fl | type2##_fl;                               \
    if (ecsname##_match(_ecs, eid, _ecsflags)) {                               \
      fname(_ecs->c_##type1 + eid, _ecs->c_##type2 + eid);                     \
    }                                                                          \
  }

#define ECS_SYSTEM3(ecsname, fname, type1, type2, type3)                       \
  void fname##_run(ecsname *_ecs, ecs_eid eid) {                               \
    ecs_cid _ecsflags = type1##_fl | type2##_fl | type3##_fl;                  \
    if (ecsname##_match(_ecs, eid, _ecsflags)) {                               \
      fname(_ecs->c_##type1 + eid, _ecs->c_##type2 + eid,                      \
            _ecs->c_##type3 + eid);                                            \
    }                                                                          \
  }

#define ECS_SYSTEM4(ecsname, fname, type1, type2, type3, type4)                \
  void fname##_run(ecsname *_ecs, ecs_eid eid) {                               \
    ecs_cid _ecsflags = type1##_fl | type2##_fl | type3##_fl | type4##_fl;     \
    if (ecsname##_match(_ecs, eid, _ecsflags)) {                               \
      fname(_ecs->c_##type1 + eid, _ecs->c_##type2 + eid,                      \
            _ecs->c_##type3 + eid, _ecs->c_##type4 + eid);                     \
    }                                                                          \
  }

#endif