#include <lexer.h>
#include <list.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <token.h>

void
Lexer::init(char *script)
{
  asprintf(&m_script, "%s", script);

  m_tokens = (List *) calloc(1, sizeof(List));
  m_tokens->init(sizeof(Token));

  m_start = 0;
  m_current = 0;
  m_end = strlen(m_script);
  m_line = 1;

  m_errored = false;
}

List *
Lexer::scan(void)
{
  while (!at_end()) {
    m_start = m_current;
    scan_token();
  }

  if (m_errored)
    return NULL;

  Token token_eof;
  token_eof.init(EOFF, "EOF", m_line);
  m_tokens->add(&token_eof);
  token_eof.clean();

  return m_tokens;
}

void
Lexer::clean(void)
{
  for (size_t i = 0; i < m_tokens->size(); i++) {
    Token *t = (Token *) m_tokens->get(i);
    t->clean();
  }

  m_tokens->clean();
  free(m_script);
}

bool
Lexer::at_end(void)
{
  return m_current >= m_end;
}

char
Lexer::advance(void)
{
  return m_script[m_current++];
}

char
Lexer::peek(void)
{
  return m_script[m_current];
}

bool
Lexer::match(char c)
{
  if (at_end())
    return false;
  if (m_script[m_current] != c)
    return false;

  m_current++;
  return true;
}

void
Lexer::string(void)
{
  while (peek() != '"' && !at_end()) {
    if (peek() == '\n')
      m_line++;

    advance();
  }

  if (at_end()) {
    printf("[-] Error: Unterminated string in line %lu\n", m_line);
    return;
  }

  int token_length = m_current - m_start - 1;
  if (token_length == 0)
    token_length++;

  char *lexeme;
  asprintf(&lexeme, "%.*s", token_length, m_script + m_start + 1);
  Token token;
  token.init(STRING, lexeme, m_line);
  m_tokens->add(&token);
  token.clean();

  advance();
}

void
Lexer::add_token(token_type_e type)
{
  int token_length = m_current - m_start;
  if (token_length == 0)
    token_length++;

  char *lexeme;
  asprintf(&lexeme, "%.*s", token_length, m_script + m_start);

  Token token;
  token.init(type, lexeme, m_line);
  m_tokens->add(&token);
  token.clean();
}

void
Lexer::scan_token(void)
{
  char c = advance();
  switch (c) {
  case '(':
    add_token(LEFT_PAREN);
    break;
  case ')':
    add_token(RIGHT_PAREN);
    break;
  case '{':
    add_token(LEFT_BRACE);
    break;
  case '}':
    add_token(RIGHT_BRACE);
    break;
  case ',':
    add_token(COMMA);
    break;
  case '.':
    add_token(DOT);
    break;
  case '-':
    add_token(MINUS);
    break;
  case '+':
    add_token(PLUS);
    break;
  case ';':
    add_token(SEMICOLON);
    break;
  case '*':
    add_token(STAR);
    break;

  case '!':
    add_token(match('=') ? BANG_EQUAL : BANG);
    break;
  case '=':
    add_token(match('=') ? EQUAL_EQUAL : EQUAL);
    break;
  case '<':
    add_token(match('=') ? LESS_EQUAL : LESS);
    break;
  case '>':
    add_token(match('=') ? GREATER_EQUAL : GREATER);
    break;

  case '"':
    string();
    break;

  case '/':
    if (match('/'))
      while (peek() != '\n' && !at_end())
        advance();
    else
      add_token(SLASH);
    break;

  case '\n':
    m_line++;
    break;

  case ' ':
  case '\r':
  case '\t':
    break;

  default:
    printf("[-] Error: Unexpected character %c in line %lu\n", c, m_line);
    m_errored = true;
    break;
  }
}