/*
* Copyright (C) 2023 Johnny Richard
*
* 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 <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "ast.h"
#include "lexer.h"
#include "parser.h"

void
parser_init(parser_t *parser, lexer_t *lexer)
{
  assert(parser && "parser must be defined");
  assert(lexer && "lexer must be defined");
  parser->lexer = lexer;
}

static token_t
expected_token(parser_t *parser, token_kind_t kind)
{
  token_t token;
  lexer_next_token(parser->lexer, &token);

  if (token.kind == TOKEN_EOF) {
    fprintf(
        stderr,
        "%s:%d:%d: [ERROR]: expected '%s' but got end of file\n",
        token.filepath, token.row + 1, token.col + 1,
        token_kind_to_str(kind)
    );
    exit(EXIT_FAILURE);
  }

  if (token.kind != kind) {
    fprintf(
        stderr,
        "%s:%d:%d: [ERROR]: expected '%s' but got '%s'\n",
        token.filepath, token.row + 1, token.col + 1,
        token_kind_to_str(kind), token_kind_to_str(token.kind)
    );
    exit(EXIT_FAILURE);
  }

  return token;
}

static type_t
parser_parse_type(parser_t *parser)
{
  token_t token = expected_token(parser, TOKEN_NAME);

  if (string_view_eq(token.value, string_view_from_str("i32"))) {
    return TYPE_I32;
  }

  fprintf(stderr, "[ERROR]: expected type 'i32' but got '"SVFMT"'\n", SVARG(&token.value)); 
  exit(EXIT_FAILURE);
}

static ast_return_stmt_t
parser_parse_return_stmt(parser_t *parser)
{
  expected_token(parser, TOKEN_OCURLY);
  token_t return_keyword_token = expected_token(parser, TOKEN_NAME);

  if (!string_view_eq(return_keyword_token.value, string_view_from_str("return"))) {
    // TODO: Add filename:row:col prefix to expected token exceptions
    fprintf(stderr, "[ERROR]: expected 'return' keyword but got '"SVFMT"'\n", SVARG(&return_keyword_token.value));
    exit(EXIT_FAILURE);
  }

  token_t number_token = expected_token(parser, TOKEN_NUMBER);
  expected_token(parser, TOKEN_SEMICOLON);
  expected_token(parser, TOKEN_CCURLY);

  char number_as_str[number_token.value.size];
  string_view_to_str(&number_token.value, number_as_str);

  return ast_return_stmt_create(atoi(number_as_str));
}

ast_function_t
parser_parse_function(parser_t *parser)
{
  token_t func_name_token = expected_token(parser, TOKEN_NAME);
  expected_token(parser, TOKEN_OPAREN);
  expected_token(parser, TOKEN_CPAREN);
  expected_token(parser, TOKEN_COLON);
  type_t return_type = parser_parse_type(parser);

  return ast_function_create(
    func_name_token.value,
    return_type,
    parser_parse_return_stmt(parser)
  );
}