/*
  Copyright 2011-2020 David Robillard <d@drobilla.net>

  Permission to use, copy, modify, and/or distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#ifndef SERD_STRING_UTILS_H
#define SERD_STRING_UTILS_H

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

/** Unicode replacement character in UTF-8 */
static const uint8_t replacement_char[] = {0xEF, 0xBF, 0xBD};

/** Return true if `c` lies within [`min`...`max`] (inclusive) */
static inline bool
in_range(const int c, const int min, const int max)
{
  return (c >= min && c <= max);
}

/** RFC2234: ALPHA ::= %x41-5A / %x61-7A  ; A-Z / a-z */
static inline bool
is_alpha(const int c)
{
  return in_range(c, 'A', 'Z') || in_range(c, 'a', 'z');
}

/** RFC2234: DIGIT ::= %x30-39  ; 0-9 */
static inline bool
is_digit(const int c)
{
  return in_range(c, '0', '9');
}

/* RFC2234: HEXDIG ::= DIGIT / "A" / "B" / "C" / "D" / "E" / "F" */
static inline bool
is_hexdig(const int c)
{
  return is_digit(c) || in_range(c, 'A', 'F');
}

/* Turtle / JSON / C: XDIGIT ::= DIGIT / A-F / a-f */
static inline bool
is_xdigit(const int c)
{
  return is_hexdig(c) || in_range(c, 'a', 'f');
}

static inline bool
is_space(const char c)
{
  switch (c) {
  case ' ':
  case '\f':
  case '\n':
  case '\r':
  case '\t':
  case '\v':
    return true;
  default:
    return false;
  }
}

static inline bool
is_print(const int c)
{
  return c >= 0x20 && c <= 0x7E;
}

static inline bool
is_windows_path(const char* path)
{
  return is_alpha(path[0]) && (path[1] == ':' || path[1] == '|') &&
         (path[2] == '/' || path[2] == '\\');
}

static inline char
serd_to_upper(const char c)
{
  return (char)((c >= 'a' && c <= 'z') ? c - 32 : c);
}

static inline int
serd_strncasecmp(const char* s1, const char* s2, size_t n)
{
  for (; n > 0 && *s2; s1++, s2++, --n) {
    if (serd_to_upper(*s1) != serd_to_upper(*s2)) {
      return ((*(const uint8_t*)s1 < *(const uint8_t*)s2) ? -1 : +1);
    }
  }

  return 0;
}

static inline uint32_t
utf8_num_bytes(const uint8_t leading)
{
  static const uint8_t lengths[32] = {
    1u, // 00000xxx
    1u, // 00001xxx
    1u, // 00010xxx
    1u, // 00011xxx
    1u, // 00100xxx
    1u, // 00101xxx
    1u, // 00110xxx
    1u, // 00111xxx
    1u, // 01000xxx
    1u, // 01001xxx
    1u, // 01010xxx
    1u, // 01011xxx
    1u, // 01100xxx
    1u, // 01101xxx
    1u, // 01110xxx
    1u, // 01111xxx
    0u, // 10000xxx
    0u, // 10001xxx
    0u, // 10010xxx
    0u, // 10011xxx
    0u, // 10100xxx
    0u, // 10101xxx
    0u, // 10110xxx
    0u, // 10111xxx
    2u, // 11000xxx
    2u, // 11001xxx
    2u, // 11010xxx
    2u, // 11011xxx
    3u, // 11100xxx
    3u, // 11101xxx
    4u, // 11110xxx
    0u  // 11111xxx
  };

  return lengths[leading >> 3u];
}

static inline unsigned
utf8_num_bytes_for_codepoint(const uint32_t code)
{
  if (code < 0x00000080) {
    return 1u;
  }

  if (code < 0x00000800) {
    return 2u;
  }

  if (code < 0x00010000) {
    return 3u;
  }

  if (code < 0x00110000) {
    return 4u;
  }

  return 0u; // Out of range
}

/// Return the code point of a UTF-8 character with known length
static inline uint32_t
parse_counted_utf8_char(const uint8_t* const utf8, const size_t size)
{
  uint32_t c = utf8[0] & ((1u << (8u - size)) - 1u);

  for (size_t i = 1; i < size; ++i) {
    c = (c << 6) | (utf8[i] & 0x3Fu);
  }

  return c;
}

/// Parse a UTF-8 character, set *size to the length, and return the code point
static inline uint32_t
parse_utf8_char(const uint8_t* const utf8, size_t* const size)
{
  switch (*size = utf8_num_bytes(utf8[0])) {
  case 1:
  case 2:
  case 3:
  case 4:
    return parse_counted_utf8_char(utf8, *size);
  default:
    *size = 0;
    return 0u;
  }
}

#endif // SERD_STRING_UTILS_H