/*************************************************************************
 * Copyright (C) 2009 Tavian Barnes <tavianator@gmail.com>               *
 *                                                                       *
 * This file is part of Dimension.                                       *
 *                                                                       *
 * Dimension 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.                                       *
 *                                                                       *
 * Dimension 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 <http://www.gnu.org/licenses/>. *
 *************************************************************************/

#include "tokenize.h"
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <sys/mman.h>
#include <unistd.h>

dmnsn_array *
dmnsn_tokenize(FILE *file)
{
  if (fseeko(file, 0, SEEK_END) != 0) {
    fprintf(stderr, "Couldn't seek on input stream.\n");
    return NULL;
  }

  off_t size = ftello(file);

  int fd = fileno(file);
  if (fd == -1) {
    fprintf(stderr, "Couldn't get file descriptor to input stream.\n");
    return NULL;
  }

  char *map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0),
    *next = map,
    *endi, *endf;

  if (map == MAP_FAILED) {
    fprintf(stderr, "Couldn't mmap() input stream.\n");
    return NULL;
  }

  dmnsn_token token;
  dmnsn_array *tokens = dmnsn_new_array(sizeof(dmnsn_token));

  unsigned int line = 1, col = 0;
  unsigned int i;

  while (next - map < size) {
    /* Saves us some code repetition */
    token.value = NULL;
    token.line  = line;
    token.col   = col;

    switch (*next) {
    case ' ':
    case '\r':
    case '\t':
    case '\f':
    case '\v':
      /* Skip whitespace */
      ++next;
      ++col;
      continue;

    case '\n':
      ++next;
      ++line;
      col = 0;
      continue;

    /* Macro to make basic symbol tokens easier */
    #define dmnsn_simple_token(c, tp)                                          \
    case c:                                                                    \
      token.type = tp;                                                         \
      break

    /* Some simple punctuation marks */
    dmnsn_simple_token('{', DMNSN_LBRACE);
    dmnsn_simple_token('}', DMNSN_RBRACE);
    dmnsn_simple_token('(', DMNSN_LPAREN);
    dmnsn_simple_token(')', DMNSN_RPAREN);
    dmnsn_simple_token('[', DMNSN_LBRACKET);
    dmnsn_simple_token(']', DMNSN_RBRACKET);
    dmnsn_simple_token('<', DMNSN_LT);
    dmnsn_simple_token('>', DMNSN_GT);
    dmnsn_simple_token('+', DMNSN_PLUS);
    dmnsn_simple_token('-', DMNSN_MINUS);
    dmnsn_simple_token('*', DMNSN_STAR);
    dmnsn_simple_token(',', DMNSN_COMMA);

    /* Possible comment */
    case '/':
      if (*(next + 1) == '/') {
        /* A '//' comment block */
        do {
          ++next;
        } while (next - map < size && *next != '\n');

        ++line;
        col = 0;
        continue;
      } else if (*(next + 1) == '*') {
        /* A '/*' comment block */
        do {
          ++col;
          if (*next == '\n') {
            ++line;
            col = 0;
          }

          ++next;
        } while (next - map < size - 1
                 && !(*next == '*' && *(next + 1) == '/'));
        next += 2;
        continue;
      } else {
        /* Just the normal punctuation mark */
        token.type = DMNSN_SLASH;
      }
      break;

    /* Numeric values */
    case '.': /* Number begins with a decimal point, as in `.2' */
    case '0':
    case '1':
    case '2':
    case '3':
    case '4':
    case '5':
    case '6':
    case '7':
    case '8':
    case '9':
      strtoul(next, &endi, 0);
      strtod(next, &endf);
      if (endf > endi
          /* These next conditions catch invalid octal integers being parsed as
             floats, eg 08 */
          && (*endi == '.' || *endi == 'e' || *endi == 'E' || *endi == 'p'
              || *endi == 'P'))
      {
        token.type = DMNSN_FLOAT;
        token.value = malloc(endf - next + 1);
        strncpy(token.value, next, endf - next);
        token.value[endf - next] = '\0';

        col += endf - next;
        next = endf;
      } else if (endi > next) {
        token.type = DMNSN_INT;
        token.value = malloc(endi - next + 1);
        strncpy(token.value, next, endi - next);
        token.value[endi - next] = '\0';

        col += endi - next;
        next = endi;
      } else {
        fprintf(stderr, "Invalid numeric value on line %u, column %u.\n",
                line, col);
        dmnsn_delete_tokens(tokens);
        munmap(map, size);
        return NULL;
      }
      break;

    default:
      /* Unrecognised character */
      fprintf(stderr,
              "Unrecognized character 0x%X in input at line %u, column %u.\n",
              (unsigned int)*next, line, col);
      dmnsn_delete_tokens(tokens);
      munmap(map, size);
      return NULL;
    }

    dmnsn_array_push(tokens, &token);
    ++next;
    ++col;
  }

  munmap(map, size);
  return tokens;
}

void
dmnsn_delete_tokens(dmnsn_array *tokens)
{
  dmnsn_token *token;
  unsigned int i;
  for (i = 0; i < dmnsn_array_size(tokens); ++i) {
    token = dmnsn_array_at(tokens, i);
    free(token->value);
  }
  dmnsn_delete_array(tokens);
}

static const char *dmnsn_token_name(dmnsn_token_type token_type);

static void
dmnsn_print_token(FILE *file, dmnsn_token *token)
{
  if (token->value) {
    fprintf(file, "(%s \"%s\")", dmnsn_token_name(token->type), token->value);
  } else {
    fprintf(file, "%s", dmnsn_token_name(token->type));
  }
}

void
dmnsn_print_token_sexpr(FILE *file, dmnsn_array *tokens)
{
  unsigned int i;
  if (dmnsn_array_size(tokens) == 0) {
    fprintf(file, "()");
  } else {
    fprintf(file, "(");
    dmnsn_print_token(file, dmnsn_array_at(tokens, 0));

    for (i = 1; i < dmnsn_array_size(tokens); ++i) {
      fprintf(file, " ");
      dmnsn_print_token(file, dmnsn_array_at(tokens, i));
    }

    fprintf(file, ")");
  }

  fprintf(file, "\n");
}

static const char *
dmnsn_token_name(dmnsn_token_type token_type)
{
  switch (token_type) {
  /* Macro to shorten this huge switch */
  #define dmnsn_token_map(type, str)                                           \
  case type:                                                                   \
    return str;

  /* Punctuation */
  dmnsn_token_map(DMNSN_LBRACE,   "{");
  dmnsn_token_map(DMNSN_RBRACE,   "}")
  dmnsn_token_map(DMNSN_LPAREN,   "\\(");
  dmnsn_token_map(DMNSN_RPAREN,   "\\)");
  dmnsn_token_map(DMNSN_LBRACKET, "[");
  dmnsn_token_map(DMNSN_RBRACKET, "]");
  dmnsn_token_map(DMNSN_LT,       "<");
  dmnsn_token_map(DMNSN_GT,       ">");
  dmnsn_token_map(DMNSN_PLUS,     "+");
  dmnsn_token_map(DMNSN_MINUS,    "-");
  dmnsn_token_map(DMNSN_STAR,     "*");
  dmnsn_token_map(DMNSN_SLASH,    "/");
  dmnsn_token_map(DMNSN_COMMA,    ",");

  /* Numeric values */
  dmnsn_token_map(DMNSN_INT,   "int");
  dmnsn_token_map(DMNSN_FLOAT, "float");

  default:
    printf("Warning: unrecognised token %d.\n", (int)token_type);
    return "unrecognized-token";
  }
}