#include "internal.h"
#include "sugar.h"
#include "silver/vm.h"

#define MCO_USE_VMEM_ALLOCATOR
#define MCO_ZERO_MEMORY
#define MCO_DEFAULT_STACK_SIZE (1024 * 1024)
#define MINICORO_IMPL
#include <minicoro.h>

uint32_t coros_this_tick = 0;
coroutine_queue_t pending_coroutines = {NULL, NULL};
static bool coro_stack_size_initialized = false;

bool has_pending_coroutines(void) {
  return pending_coroutines.head != NULL;
}

bool has_ready_coroutines(void) {
  coroutine_t *temp = pending_coroutines.head;
  while (temp) {
    if (temp->is_ready) return true;
    temp = temp->next;
  }
  return false;
}

void enqueue_coroutine(coroutine_t *coro) {
  if (!coro) return;
  coro->next = NULL;
  coro->prev = pending_coroutines.tail;
  
  if (pending_coroutines.tail) {
    pending_coroutines.tail->next = coro;
  } else pending_coroutines.head = coro;
  pending_coroutines.tail = coro;
}

void remove_coroutine(coroutine_t *coro) {
  if (!coro) return;
  
  if (coro->prev) {
    coro->prev->next = coro->next;
  } else pending_coroutines.head = coro->next;
  
  if (coro->next) {
    coro->next->prev = coro->prev;
  } else pending_coroutines.tail = coro->prev;
  
  coro->prev = NULL;
  coro->next = NULL;
}

void free_coroutine(coroutine_t *coro) {
  if (!coro) return;
  
  if (coro->mco) {
    if (mco_running() == coro->mco) fprintf(stderr, "WARNING: Attempting to free a running coroutine\n");
    void *ctx = mco_get_user_data(coro->mco);
    if (ctx) CORO_FREE(ctx);
    mco_destroy(coro->mco);
    coro->mco = NULL;
  }
  
  if (coro->args) CORO_FREE(coro->args);
  if (coro->sv_vm) { sv_vm_destroy(coro->sv_vm); coro->sv_vm = NULL; }
  
  CORO_FREE(coro);
}

static size_t calculate_coro_stack_size(void) {
  static size_t cached_size = 0;
  if (coro_stack_size_initialized) return cached_size;
  coro_stack_size_initialized = true;
  const char *env_stack = getenv("ANT_CORO_STACK_SIZE");
  if (env_stack) {
    size_t size = (size_t)atoi(env_stack) * 1024;
    if (size >= 32 * 1024 && size <= 8 * 1024 * 1024) { 
      cached_size = size; return cached_size; 
    }
  }
  return cached_size;
}

static inline void settle_coroutine(coroutine_t *coro, ant_value_t *args, int nargs, bool is_error) {
  coro->result = nargs > 0 ? args[0] : js_mkundef();
  coro->is_settled = true;
  coro->is_error = is_error;
  coro->is_ready = true;
}

static void resume_coroutine_if_suspended(ant_t *js, coroutine_t *coro) {
  if (!coro || !coro->mco || mco_status(coro->mco) != MCO_SUSPENDED) return;

  coro->is_ready = false;
  mco_result res;
  MCO_RESUME_SAVE(js, coro->mco, res);

  if (res != MCO_SUCCESS || mco_status(coro->mco) == MCO_DEAD) {
    remove_coroutine(coro);
    free_coroutine(coro);
  }
}

ant_value_t resume_coroutine_wrapper(ant_t *js, ant_value_t *args, int nargs) {
  ant_value_t me = js->current_func;
  ant_value_t coro_val = js_get_slot(me, SLOT_CORO);
  if (vtype(coro_val) != T_NUM) return js_mkundef();
  
  coroutine_t *coro = (coroutine_t *)(uintptr_t)tod(coro_val);
  if (!coro) return js_mkundef();

  settle_coroutine(coro, args, nargs, false);
  resume_coroutine_if_suspended(js, coro);

  return js_mkundef();
}

ant_value_t reject_coroutine_wrapper(ant_t *js, ant_value_t *args, int nargs) {
  ant_value_t me = js->current_func;
  ant_value_t coro_val = js_get_slot(me, SLOT_CORO);
  
  if (vtype(coro_val) != T_NUM) return js_mkundef();
  
  coroutine_t *coro = (coroutine_t *)(uintptr_t)tod(coro_val);
  if (!coro) return js_mkundef();

  settle_coroutine(coro, args, nargs, true);
  resume_coroutine_if_suspended(js, coro);

  return js_mkundef();
}