/*
 * Copyright (C) 2023 Carlos Maniero
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
#include "scope.h"
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>

static scope_item_t *
scope_item_new(void)
{
  scope_item_t *item = malloc(sizeof(scope_item_t));
  if (item == NULL) {
    fprintf(stderr, "failed to create scope item: %s\n", strerror(errno));
    exit(EXIT_FAILURE);
  }
  return item;
}

static void
scope_item_destroy(scope_item_t *item)
{
  free(item);
}

scope_t *
scope_new(void)
{
  scope_t *scope = malloc(sizeof(scope_t));

  if (scope == NULL) {
    fprintf(stderr, "failed to create scope: %s\n", strerror(errno));
    exit(EXIT_FAILURE);
  }

  scope->stack = vector_new();
  scope_enter(scope);
  return scope;
}

void
scope_destroy(scope_t *scope)
{
  if (scope->stack->size != 1) {
    fprintf(stderr,
            "Stack not cleaned before destroying. This may lead to memory leaks.\n"
            "Please make sure to call the leave function before destroying it.");
    assert(scope->stack->size == 1);
  }

  for (size_t i = 0; i < scope->stack->size; i++) {
    vector_destroy(vector_at(scope->stack, i));
  }

  vector_destroy(scope->stack);
  free(scope);
}

void
scope_enter(scope_t *scope)
{
  vector_push_back(scope->stack, vector_new());
}

void
scope_leave(scope_t *scope)
{
  // FIXME: create a stack data structure to simplify this logic
  vector_t *new_stack = vector_new();

  for (size_t i = 0; i < scope->stack->size - 1; i++) {
    vector_push_back(new_stack, vector_at(scope->stack, i));
  }

  vector_t *current_level = vector_at(scope->stack, scope->stack->size - 1);

  for (size_t i = 0; i < current_level->size; i++) {
    scope_item_destroy(vector_at(current_level, i));
  }

  vector_destroy(current_level);
  vector_t *old_stack = scope->stack;
  vector_destroy(old_stack);
  scope->stack = new_stack;
}

ast_node_t *
scope_get(scope_t *scope, string_view_t name)
{
  for (size_t i = scope->stack->size; i > 0; i--) {
    vector_t *current_level = vector_at(scope->stack, i - 1);

    for (size_t j = 0; j < current_level->size; j++) {
      scope_item_t *item = vector_at(current_level, j);

      if (string_view_eq(name, item->identifier->name)) {
        return item->node;
      }
    }
  }

  return NULL;
}

void
scope_push(scope_t *scope, ast_identifier_t *identifier, ast_node_t *node)
{
  vector_t *current_level = vector_at(scope->stack, scope->stack->size - 1);
  scope_item_t *item = scope_item_new();
  *item = (scope_item_t){ .identifier = identifier, .node = node };
  vector_push_back(current_level, item);
}