#include <compiler/fzl_reader.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// Last error from reader
static char last_err[256] = {0};

fzl_reader_t *fzl_mkreader(char *source)
{
  fzl_reader_ll_t *first_node = malloc(sizeof(fzl_reader_ll_t));
  first_node->token = NULL;
  first_node->next = NULL;

  fzl_reader_t *reader = malloc(sizeof(fzl_reader_t));
  reader->first = first_node;
  reader->last = first_node;
  reader->source = source;
  reader->size = strlen(source);
  reader->position = 0;
  reader->at_end = true;

  return reader;
}

// --- Read zone ---

// Try parse name
fzl_token_t *parse_name(fzl_reader_t *reader)
{
  size_t lpos = reader->position;
  size_t size = 0;

  do
  {
    lpos++;
    size++;
  } while ((reader->source[lpos] >= 'A' && reader->source[lpos] <= 'Z') ||
           (reader->source[lpos] >= 'a' && reader->source[lpos] <= 'z'));

  char *value = malloc(size);
  memcpy(value, reader->source + reader->position, size);

  size_t start = reader->position;
  reader->position += size;

  fzl_token_t *tok =
      fzl_mktoken(FZL_TOKTYPE_NAME, start, reader->position - 1, value, size);
  free(value);

  return tok;
}

// Try parse string literal
fzl_token_t *parse_string_literal(fzl_reader_t *reader)
{
  size_t lpos = reader->position;
  size_t size = 0;

  if (reader->source[lpos] != '\'' && reader->source[lpos] != '"')
    return NULL;

  char open_symbol = reader->source[lpos];
  char close_symbol = '\0';

  do
  {
    lpos++;
    size++;

    if (reader->source[lpos] == open_symbol)
      close_symbol = open_symbol;

  } while (reader->source[lpos] != open_symbol && lpos < reader->size);
  size++;

  if (close_symbol != open_symbol)
    return NULL;

  if (size == 2)
  {
    fzl_token_t *tok = fzl_mktoken(FZL_TOKTYPE_STR_LITERAL, reader->position,
                                   reader->position + 1, "", 0);
    reader->position += 2;
    return tok;
  }

  char *value = malloc(size - 2);
  memcpy(value, reader->source + reader->position + 1, size - 2);
  fzl_token_t *tok = fzl_mktoken(FZL_TOKTYPE_STR_LITERAL, reader->position,
                                 lpos, value, size - 2);
  free(value);

  reader->position += size;

  return tok;
}

int fzl_read(fzl_reader_t *reader)
{
  if (reader->position >= reader->size)
    return 0;

  do
  {
    size_t p = reader->position;
    fzl_token_t *token;
    char curr = reader->source[p];

    if (curr == '\n' || curr == ' ' || curr == '\r')
    {
      reader->position++;
      continue;
    }

    if (curr == '\'' || curr == '"')
      token = parse_string_literal(reader);
    else if (curr == '(')
    {
      token = fzl_mktoken(FZL_TOKTYPE_LPAIR, p, p, NULL, 0);
      reader->position++;
    }
    else if (curr == ')')
    {
      token = fzl_mktoken(FZL_TOKTYPE_RPAIR, p, p, NULL, 0);
      reader->position++;
    }
    else if (curr >= 'A' && curr <= 'Z' || curr >= 'a' && curr <= 'z')
      token = parse_name(reader);
    else
    {
      sprintf(last_err, "undefined token '%c'", curr);
      return -1;
    }

    if (!token)
    {
      size_t line = 1, linepos = 1;
      for (size_t i = 0; i < p; i++)
      {
        char sym = reader->source[i];
        if (sym == '\n')
        {
          linepos = 1;
          line++;
        }
        else
          linepos++;
      }

      sprintf(last_err, "cannot parse token (%ld:%ld)", line, linepos);
      return -1;
    }

    fzl_reader_ll_t *tok_node = malloc(sizeof(fzl_reader_ll_t));
    tok_node->token = token;

    reader->last->next = tok_node;
    reader->last = tok_node;
  } while (reader->position < reader->size);

  reader->at_end = true;
  return 0;
}

// --- Read zone end ---

char *fzl_reader_geterror() { return last_err; }

void free_node_and_next(fzl_reader_ll_t *node)
{
  if (!node)
    return;
  if (node->next)
    free_node_and_next(node->next);

  if (node->token)
    fzl_freetoken(node->token);

  free(node);
}

void fzl_freereader(fzl_reader_t *reader)
{
  if (!reader)
    return;
  if (reader->first)
    free_node_and_next(reader->first);

  free(reader);
}