#ifdef MD_INTELLISENSE_DIRECTIVES
#pragma once
#include "base_types.h"
#include "macros.h"
#endif

// Copyright (c) 2024 Epic Games Tools
// Licensed under the MIT license (https://opensource.org/license/mit/)

////////////////////////////////
//~ rjf: Constants

#define MD_ARENA_HEADER_SIZE 64

////////////////////////////////
//~ rjf: Types

typedef U32 ArenaFlags;
enum
{
  ArenaFlag_NoChain    = (1<<0),
  ArenaFlag_LargePages = (1<<1),
};

typedef struct ArenaParams ArenaParams;
struct ArenaParams
{
  ArenaFlags flags;
  U64 reserve_size;
  U64 commit_size;
  void *optional_backing_buffer;
};

typedef struct Arena Arena;
struct Arena
{
  Arena *prev;    // previous arena in chain
  Arena *current; // current arena in chain
  ArenaFlags flags;
  U32 cmt_size;
  U64 res_size;
  U64 base_pos;
  U64 pos;
  U64 cmt;
  U64 res;
};
static_assert(sizeof(Arena) <= MD_ARENA_HEADER_SIZE, "sizeof(Arena) <= MD_ARENA_HEADER_SIZE");

typedef struct TempArena TempArena;
struct TempArena
{
  Arena *arena;
  U64 pos;
};

////////////////////////////////
//~ rjf: Arena Functions

//- rjf: arena creation/destruction
internal Arena *arena_alloc_(ArenaParams *params);
#define arena_alloc(...) arena_alloc_(&(ArenaParams){.reserve_size = MB(64), .commit_size = KB(64), __VA_ARGS__})
internal void rarena_release(Arena *arena);

//- rjf: arena push/pop/pos core functions
internal void *arena_push(Arena *arena, U64 size, U64 align);
internal U64   arena_pos(Arena *arena);
internal void  arena_pop_to(Arena *arena, U64 pos);

//- rjf: arena push/pop helpers
internal void arena_clear(Arena *arena);
internal void arena_pop(Arena *arena, U64 amt);

//- rjf: temporary arena scopes
internal TempArena temp_arena_begin(Arena *arena);
internal void      temp_arena_end(TempArena temp);

//- rjf: push helper macros
#define push_array_no_zero_aligned(a, T, c, align) (T *)arena_push((a), sizeof(T)*(c), (align))
#define push_array_aligned(a, T, c, align) (T *)MemoryZero(push_array_no_zero_aligned(a, T, c, align), sizeof(T)*(c))
#define push_array_no_zero(a, T, c) push_array_no_zero_aligned(a, T, c, Max(8, AlignOf(T)))
#define push_array(a, T, c) push_array_aligned(a, T, c, Max(8, AlignOf(T)))