#include <compiler/fzl_parser.h>
#include <compiler/fzl_token.h>
#include <compiler/internals/parser.h>
#include <stdio.h>
#include <stdlib.h>

// Parse external function
fzl_node_t *pa_externfn(fzl_parser_t *parser)
{
  if (!parser || !peek(parser))
    return NULL;

  fzl_token_t *tok = consume(parser);
  if (!tok || tok->type != FZL_TOKTYPE_FUNCTION)
  {
    snprintf(plast_err, sizeof(plast_err),
             "'%s':%zu:%zu => expected 'function' keyword",
             last_known_tok->filename, last_known_tok->ln, last_known_tok->cn);
    return NULL;
  }

  fzl_token_t *name = consume(parser);
  if (!name || name->type != FZL_TOKTYPE_NAME)
  {
    snprintf(plast_err, sizeof(plast_err),
             "'%s':%zu:%zu => expected function name after 'fn'",
             last_known_tok->filename, last_known_tok->ln, last_known_tok->cn);
    return NULL;
  }

  fzl_token_t *lpar = consume(parser);
  if (!lpar || lpar->type != FZL_TOKTYPE_LPAREN)
  {
    snprintf(plast_err, sizeof(plast_err),
             "'%s':%zu:%zu => expected '(' after function name",
             last_known_tok->filename, last_known_tok->ln, last_known_tok->cn);
    return NULL;
  }

  size_t remainder  = 2;
  size_t count      = 0;
  fzl_node_t **args = malloc(remainder * sizeof(fzl_node_t *));
  if (!args)
  {
    snprintf(plast_err, sizeof(plast_err), "out of memory");
    return NULL;
  }

  while (peek(parser) && !is(parser, FZL_TOKTYPE_RPAREN))
  {
    if (remainder <= count)
    {
      remainder *= 2;
      fzl_node_t **newarr = realloc(args, remainder * sizeof(fzl_node_t *));
      if (!newarr)
      {
        for (size_t i = 0; i < count; i++)
          fzl_freeast(args[i]);
        free(args);
        snprintf(plast_err, sizeof(plast_err), "out of memory");
        return NULL;
      }
      args = newarr;
    }

    bool is_out = false;
    if (is(parser, FZL_TOKTYPE_OUT))
    {
      consume(parser);
      is_out = true;
    }

    fzl_node_t *node = pa_expression(parser);
    if (!node || node->type != FZL_NODETYPE_DECLARATION)
    {
      for (size_t i = 0; i < count; i++)
        fzl_freeast(args[i]);
      free(args);

      if (!plast_err[0])
        snprintf(plast_err, sizeof(plast_err),
                 "'%s':%zu:%zu => expected declaration",
                 last_known_tok->filename, last_known_tok->ln,
                 last_known_tok->cn);
      return NULL;
    }

    node->var.is_out = is_out;
    args[count++]    = node;

    if (is(parser, FZL_TOKTYPE_RPAREN))
      break;

    fzl_token_t *comma = consume(parser);
    if (!comma || comma->type != FZL_TOKTYPE_COMMA)
    {
      for (size_t i = 0; i < count; i++)
        fzl_freeast(args[i]);
      free(args);
      snprintf(plast_err, sizeof(plast_err),
               "'%s':%zu:%zu => missing ',' between arguments",
               last_known_tok->filename, last_known_tok->ln,
               last_known_tok->cn);
      return NULL;
    }
  }

  fzl_token_t *rpar = consume(parser);
  if (!rpar || rpar->type != FZL_TOKTYPE_RPAREN)
  {
    for (size_t i = 0; i < count; i++)
      fzl_freeast(args[i]);
    free(args);
    snprintf(plast_err, sizeof(plast_err),
             "'%s':%zu:%zu => expected ')' after arguments list",
             last_known_tok->filename, last_known_tok->ln, last_known_tok->cn);
    return NULL;
  }

  char *original_name = NULL;
  fzl_token_t *type   = &null_tok;
  if (is(parser, FZL_TOKTYPE_NAME) || is(parser, FZL_TOKTYPE_TYPE))
    type = consume(parser);

  if (is(parser, FZL_TOKTYPE_EQ))
  {
    consume(parser);
    fzl_token_t *orig = consume(parser);

    if (!orig || orig->type != FZL_TOKTYPE_STR_LITERAL)
    {
      for (size_t i = 0; i < count; i++)
        fzl_freeast(args[i]);
      free(args);

      snprintf(plast_err, sizeof(plast_err),
               "'%s':%zu:%zu => expected original function name",
               last_known_tok->filename, last_known_tok->ln,
               last_known_tok->cn);
      return NULL;
    }

    original_name = (char *)orig->value;
  }

  fzl_node_t *node           = fzl_mknode(FZL_NODETYPE_EXTERN_FN, tok);
  node->ext_fn.name          = (char *)name->value;
  node->ext_fn.original_name = original_name;
  node->ext_fn.args_count    = count;
  node->ext_fn.args          = args;
  node->ext_fn.type          = type;

  return node;
}