/*
 * 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 2
 * 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
 * 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, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

/** \file
 * \ingroup sptext
 */

#include <string.h>

#include "BLI_blenlib.h"

#include "DNA_space_types.h"
#include "DNA_text_types.h"

#include "BKE_text.h"

#include "text_format.h"

/* *** Local Functions (for format_line) *** */

/**
 * Checks the specified source string for a Python built-in function name. This
 * name must start at the beginning of the source string and must be followed by
 * a non-identifier (see #text_check_identifier(char)) or null character.
 *
 * If a built-in function is found, the length of the matching name is returned.
 * Otherwise, -1 is returned.
 *
 * See:
 * http://docs.python.org/py3k/reference/lexical_analysis.html#keywords
 */
static int txtfmt_py_find_builtinfunc(const char *string)
{
  int i, len;
  /* list is from...
   * ", ".join(['"%s"' % kw
   *            for kw in  __import__("keyword").kwlist
   *            if kw not in {"False", "None", "True", "def", "class"}])
   *
   * ... and for this code:
   * print("\n".join(['else if (STR_LITERAL_STARTSWITH(string, "%s", len)) i = len;' % kw
   *                  for kw in  __import__("keyword").kwlist
   *                  if kw not in {"False", "None", "True", "def", "class"}]))
   */

  /* Keep aligned args for readability. */
  /* clang-format off */

  if        (STR_LITERAL_STARTSWITH(string, "assert",   len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "async",    len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "await",    len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "and",      len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "as",       len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "break",    len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "continue", len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "del",      len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "elif",     len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "else",     len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "except",   len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "finally",  len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "for",      len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "from",     len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "global",   len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "if",       len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "import",   len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "in",       len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "is",       len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "lambda",   len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "nonlocal", len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "not",      len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "or",       len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "pass",     len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "raise",    len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "return",   len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "try",      len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "while",    len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "with",     len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "yield",    len)) { i = len;
  } else                                                      { i = 0;
  }

  /* clang-format on */

  /* If next source char is an identifier (eg. 'i' in "definite") no match */
  if (i == 0 || text_check_identifier(string[i])) {
    return -1;
  }
  return i;
}

/* Checks the specified source string for a Python special name. This name must
 * start at the beginning of the source string and must be followed by a non-
 * identifier (see text_check_identifier(char)) or null character.
 *
 * If a special name is found, the length of the matching name is returned.
 * Otherwise, -1 is returned. */

static int txtfmt_py_find_specialvar(const char *string)
{
  int i, len;

  /* Keep aligned args for readability. */
  /* clang-format off */

  if        (STR_LITERAL_STARTSWITH(string, "def", len))   { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "class", len)) { i = len;
  } else                                                   { i = 0;
  }

  /* clang-format on */

  /* If next source char is an identifier (eg. 'i' in "definite") no match */
  if (i == 0 || text_check_identifier(string[i])) {
    return -1;
  }
  return i;
}

static int txtfmt_py_find_decorator(const char *string)
{
  if (string[0] != '@') {
    return -1;
  }
  if (!text_check_identifier(string[1])) {
    return -1;
  }
  /* Interpret as matrix multiplication when followed by whitespace. */
  if (text_check_whitespace(string[1])) {
    return -1;
  }

  int i = 1;
  while (text_check_identifier(string[i])) {
    i++;
  }
  return i;
}

static int txtfmt_py_find_bool(const char *string)
{
  int i, len;

  /* Keep aligned args for readability. */
  /* clang-format off */

  if        (STR_LITERAL_STARTSWITH(string, "None",  len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "True",  len)) { i = len;
  } else if (STR_LITERAL_STARTSWITH(string, "False", len)) { i = len;
  } else                                                   { i = 0;
  }

  /* clang-format on */

  /* If next source char is an identifier (eg. 'i' in "Nonetheless") no match */
  if (i == 0 || text_check_identifier(string[i])) {
    return -1;
  }
  return i;
}

/* Numeral character matching. */
#define TXTFMT_PY_NUMERAL_STRING_COUNT_IMPL(txtfmt_py_numeral_char_is_fn) \
  { \
    uint count = 0; \
    for (; txtfmt_py_numeral_char_is_fn(*string); string += 1) { \
      count += 1; \
    } \
    return count; \
  } \
  ((void)0)

/* Binary. */
static bool txtfmt_py_numeral_char_is_binary(const char c)
{
  return ELEM(c, '0', '1') || (c == '_');
}
static uint txtfmt_py_numeral_string_count_binary(const char *string)
{
  TXTFMT_PY_NUMERAL_STRING_COUNT_IMPL(txtfmt_py_numeral_char_is_binary);
}

/* Octal. */
static bool txtfmt_py_numeral_char_is_octal(const char c)
{
  return (c >= '0' && c <= '7') || (c == '_');
}
static uint txtfmt_py_numeral_string_count_octal(const char *string)
{
  TXTFMT_PY_NUMERAL_STRING_COUNT_IMPL(txtfmt_py_numeral_char_is_octal);
}

/* Decimal. */
static bool txtfmt_py_numeral_char_is_decimal(const char c)
{
  return (c >= '0' && c <= '9') || (c == '_');
}
static uint txtfmt_py_numeral_string_count_decimal(const char *string)
{
  TXTFMT_PY_NUMERAL_STRING_COUNT_IMPL(txtfmt_py_numeral_char_is_decimal);
}

/* Hexadecimal. */
static bool txtfmt_py_numeral_char_is_hexadecimal(const char c)
{
  return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F') || (c == '_');
}
static uint txtfmt_py_numeral_string_count_hexadecimal(const char *string)
{
  TXTFMT_PY_NUMERAL_STRING_COUNT_IMPL(txtfmt_py_numeral_char_is_hexadecimal);
}

/* Zeros. */
static bool txtfmt_py_numeral_char_is_zero(const char c)
{
  return (ELEM(c, '0', '_'));
}
static uint txtfmt_py_numeral_string_count_zeros(const char *string)
{
  TXTFMT_PY_NUMERAL_STRING_COUNT_IMPL(txtfmt_py_numeral_char_is_zero);
}

#undef TXTFMT_PY_NUMERAL_STRING_COUNT_IMPL

static int txtfmt_py_find_numeral_inner(const char *string)
{
  if (string == NULL || *string == '\0') {
    return -1;
  }

  const char first = *string, second = *(string + 1);

  /* Decimal dot must be followed by a digit, any decimal digit.
   * Note that the there can be any number of leading zeros after
   * the decimal point (leading zeros are not allowed in integers) */
  if (first == '.') {
    if (text_check_digit(second)) {
      return 1 + txtfmt_py_numeral_string_count_decimal(string + 1);
    }
  }
  else if (first == '0') {
    /* Numerals starting with '0x' or '0X' is followed by hexadecimal digits. */
    if (ELEM(second, 'x', 'X')) {
      return 2 + txtfmt_py_numeral_string_count_hexadecimal(string + 2);
    }
    /* Numerals starting with '0o' or '0O' is followed by octal digits. */
    if (ELEM(second, 'o', 'O')) {
      return 2 + txtfmt_py_numeral_string_count_octal(string + 2);
    }
    /* Numerals starting with '0b' or '0B' is followed by binary digits. */
    if (ELEM(second, 'b', 'B')) {
      return 2 + txtfmt_py_numeral_string_count_binary(string + 2);
    }
    /* Other numerals starting with '0' can be followed by any number of '0' characters. */
    if (ELEM(second, '0', '_')) {
      return 2 + txtfmt_py_numeral_string_count_zeros(string + 2);
    }
  }
  /* Any non-zero digit is the start of a decimal number. */
  else if (first > '0' && first <= '9') {
    return 1 + txtfmt_py_numeral_string_count_decimal(string + 1);
  }
  /* A single zero is also allowed. */
  return (first == '0') ? 1 : 0;
}

static int txtfmt_py_literal_numeral(const char *string, char prev_fmt)
{
  if (string == NULL || *string == '\0') {
    return -1;
  }

  const char first = *string, second = *(string + 1);

  if (prev_fmt == FMT_TYPE_NUMERAL) {
    /* Previous was a number; if immediately followed by 'e' or 'E' and a digit,
     * it's a base 10 exponent (scientific notation). */
    if (ELEM(first, 'e', 'E') && (text_check_digit(second) || second == '-')) {
      return 1 + txtfmt_py_find_numeral_inner(string + 1);
    }
    /* Previous was a number; if immediately followed by '.' it's a floating point decimal number.
     * NOTE: keep the decimal point, it's needed to allow leading zeros. */
    if (first == '.') {
      return txtfmt_py_find_numeral_inner(string);
    }
    /* "Imaginary" part of a complex number ends with 'j' */
    if (ELEM(first, 'j', 'J') && !text_check_digit(second)) {
      return 1;
    }
  }
  else if ((prev_fmt != FMT_TYPE_DEFAULT) &&
           (text_check_digit(first) || (first == '.' && text_check_digit(second)))) {
    /* New numeral, starting with a digit or a decimal point followed by a digit. */
    return txtfmt_py_find_numeral_inner(string);
  }
  /* Not a literal numeral. */
  return 0;
}

static char txtfmt_py_format_identifier(const char *str)
{
  char fmt;

  /* Keep aligned args for readability. */
  /* clang-format off */

  if        (txtfmt_py_find_specialvar(str)   != -1) { fmt = FMT_TYPE_SPECIAL;
  } else if (txtfmt_py_find_builtinfunc(str)  != -1) { fmt = FMT_TYPE_KEYWORD;
  } else if (txtfmt_py_find_decorator(str)    != -1) { fmt = FMT_TYPE_RESERVED;
  } else                                             { fmt = FMT_TYPE_DEFAULT;
  }

  /* clang-format on */
  return fmt;
}

static void txtfmt_py_format_line(SpaceText *st, TextLine *line, const bool do_next)
{
  FlattenString fs;
  const char *str;
  char *fmt;
  char cont_orig, cont, find, prev = ' ';
  int len, i;

  /* Get continuation from previous line */
  if (line->prev && line->prev->format != NULL) {
    fmt = line->prev->format;
    cont = fmt[strlen(fmt) + 1]; /* Just after the null-terminator */
    BLI_assert((FMT_CONT_ALL & cont) == cont);
  }
  else {
    cont = FMT_CONT_NOP;
  }

  /* Get original continuation from this line */
  if (line->format != NULL) {
    fmt = line->format;
    cont_orig = fmt[strlen(fmt) + 1]; /* Just after the null-terminator */
    BLI_assert((FMT_CONT_ALL & cont_orig) == cont_orig);
  }
  else {
    cont_orig = 0xFF;
  }

  len = flatten_string(st, &fs, line->line);
  str = fs.buf;
  if (!text_check_format_len(line, len)) {
    flatten_string_free(&fs);
    return;
  }
  fmt = line->format;

  while (*str) {
    /* Handle escape sequences by skipping both \ and next char */
    if (*str == '\\') {
      *fmt = prev;
      fmt++;
      str++;
      if (*str == '\0') {
        break;
      }
      *fmt = prev;
      fmt++;
      str += BLI_str_utf8_size_safe(str);
      continue;
    }
    /* Handle continuations */
    if (cont) {
      /* Triple strings ("""...""" or '''...''') */
      if (cont & FMT_CONT_TRIPLE) {
        find = (cont & FMT_CONT_QUOTEDOUBLE) ? '"' : '\'';
        if (*str == find && *(str + 1) == find && *(str + 2) == find) {
          *fmt = FMT_TYPE_STRING;
          fmt++;
          str++;
          *fmt = FMT_TYPE_STRING;
          fmt++;
          str++;
          cont = FMT_CONT_NOP;
        }
        /* Handle other strings */
      }
      else {
        find = (cont & FMT_CONT_QUOTEDOUBLE) ? '"' : '\'';
        if (*str == find) {
          cont = FMT_CONT_NOP;
        }
      }

      *fmt = FMT_TYPE_STRING;
      str += BLI_str_utf8_size_safe(str) - 1;
    }
    /* Not in a string... */
    else {
      /* Deal with comments first */
      if (*str == '#') {
        /* fill the remaining line */
        text_format_fill(&str, &fmt, FMT_TYPE_COMMENT, len - (int)(fmt - line->format));
      }
      else if (ELEM(*str, '"', '\'')) {
        /* Strings */
        find = *str;
        cont = (*str == '"') ? FMT_CONT_QUOTEDOUBLE : FMT_CONT_QUOTESINGLE;
        if (*(str + 1) == find && *(str + 2) == find) {
          *fmt = FMT_TYPE_STRING;
          fmt++;
          str++;
          *fmt = FMT_TYPE_STRING;
          fmt++;
          str++;
          cont |= FMT_CONT_TRIPLE;
        }
        *fmt = FMT_TYPE_STRING;
      }
      /* White-space (all ws. has been converted to spaces). */
      else if (*str == ' ') {
        *fmt = FMT_TYPE_WHITESPACE;
      }
      /* Literal numerals, "numbers". */
      else if ((i = txtfmt_py_literal_numeral(str, prev)) > 0) {
        text_format_fill(&str, &fmt, FMT_TYPE_NUMERAL, i);
      }
      /* Booleans */
      else if (prev != FMT_TYPE_DEFAULT && (i = txtfmt_py_find_bool(str)) != -1) {
        if (i > 0) {
          text_format_fill_ascii(&str, &fmt, FMT_TYPE_NUMERAL, i);
        }
        else {
          str += BLI_str_utf8_size_safe(str) - 1;
          *fmt = FMT_TYPE_DEFAULT;
        }
      }
      /* Punctuation */
      else if ((*str != '@') && text_check_delim(*str)) {
        *fmt = FMT_TYPE_SYMBOL;
      }
      /* Identifiers and other text (no previous ws. or delims. so text continues) */
      else if (prev == FMT_TYPE_DEFAULT) {
        str += BLI_str_utf8_size_safe(str) - 1;
        *fmt = FMT_TYPE_DEFAULT;
      }
      /* Not ws, a digit, punct, or continuing text. Must be new, check for special words */
      else {
        /* Keep aligned args for readability. */
        /* clang-format off */

        /* Special vars(v) or built-in keywords(b) */
        /* keep in sync with 'txtfmt_py_format_identifier()' */
        if        ((i = txtfmt_py_find_specialvar(str))   != -1) { prev = FMT_TYPE_SPECIAL;
        } else if ((i = txtfmt_py_find_builtinfunc(str))  != -1) { prev = FMT_TYPE_KEYWORD;
        } else if ((i = txtfmt_py_find_decorator(str))    != -1) { prev = FMT_TYPE_DIRECTIVE;
        }

        /* clang-format on */

        if (i > 0) {
          if (prev == FMT_TYPE_DIRECTIVE) { /* can contain utf8 */
            text_format_fill(&str, &fmt, prev, i);
          }
          else {
            text_format_fill_ascii(&str, &fmt, prev, i);
          }
        }
        else {
          str += BLI_str_utf8_size_safe(str) - 1;
          *fmt = FMT_TYPE_DEFAULT;
        }
      }
    }
    prev = *fmt;
    fmt++;
    str++;
  }

  /* Terminate and add continuation char */
  *fmt = '\0';
  fmt++;
  *fmt = cont;

  /* If continuation has changed and we're allowed, process the next line */
  if (cont != cont_orig && do_next && line->next) {
    txtfmt_py_format_line(st, line->next, do_next);
  }

  flatten_string_free(&fs);
}

void ED_text_format_register_py(void)
{
  static TextFormatType tft = {NULL};
  static const char *ext[] = {"py", NULL};

  tft.format_identifier = txtfmt_py_format_identifier;
  tft.format_line = txtfmt_py_format_line;
  tft.ext = ext;

  ED_text_format_register(&tft);
}