<?php
/*************************************************************
# 076 License

Copyright (c) テクニカル諏訪子

Permission is hereby granted to any person obtaining a copy of the software
Little Beast (the "Software") to use, modify, merge, copy, publish, distribute,
sublicense, and/or sell copies of the Software, subject to the following conditions:

    1. **Origin Attribution**:
       - You must not misrepresent the origin of the Software; you must not claim
         you created the original Software.
       - If the Software is used in a product, you must either:
         a. Provide clear attribution in the product's documentation, user interface,
            or other visible areas, **OR**
         b. Pay the original developers a fee they specify in writing.
    2. **Usage Restriction**:
       - The Software, or any derivative works, dependencies, or libraries
         incorporating it, must not be used for censorship or to suppress freedom of
         speech, expression, or creativity. Prohibited uses include, but are not
         limited to:
         - Censorship of so-called "hate speech", visuals, non-mainstream opinions,
           ideas, or objective reality.
         - Tools or systems designed to restrict access to information or
           artistic works.
    3. **Notice Preservation**:
       - This license and the above copyright notice must remain intact in all copies
         of the source code.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
namespace Std\Lib\Db\Sqlite;

/**
 * SQLiteのレコードの形式（可変長整数、シリアル型）と値の比較
 *
 * 値の表し方：null、int、float、string（TEXT）、Blob（BLOB）。
 */
final class Record {
  /**
   * 可変長整数を読む（ビッグエンディアン、1バイト7ビット、9バイト目は8ビット）
   *
   * @param string $b  データ
   * @param int $pos  位置（読んだ分だけ進む）
   * @return int  64ビットの符号付き整数
   */
  public static function getVarint(string $b, int &$pos): int {
    $c = ord($b[$pos++] ?? "\0");
    if ($c < 0x80) return $c;
    $v = $c & 0x7F;
    for ($i = 1; $i < 8; $i++) {
      $c = ord($b[$pos++] ?? "\0");
      $v = ($v << 7) | ($c & 0x7F);
      if ($c < 0x80) return $v;
    }
    return ($v << 8) | ord($b[$pos++] ?? "\0");
  }

  /**
   * 可変長整数を書く
   *
   * @param int $v  値（負の数は64ビットの符号なしとして書く）
   * @return string
   */
  public static function putVarint(int $v): string {
    if ($v >= 0 && $v < 0x80) return chr($v);
    if ($v < 0 || $v > 0x00FFFFFFFFFFFFFF) {
      // 9バイト：最後のバイトは8ビット
      $out = chr($v & 0xFF);
      $v = ($v >> 8) & 0x00FFFFFFFFFFFFFF;
      for ($i = 0; $i < 8; $i++) {
        $out = chr(($v & 0x7F) | 0x80).$out;
        $v >>= 7;
      }
      return $out;
    }
    $out = chr($v & 0x7F);
    $v >>= 7;
    while ($v > 0) {
      $out = chr(($v & 0x7F) | 0x80).$out;
      $v >>= 7;
    }
    return $out;
  }

  /** 可変長整数のバイト数 */
  public static function varintLen(int $v): int {
    if ($v < 0) return 9;
    for ($n = 1; $n < 9; $n++) {
      if ($v < (1 << (7 * $n))) return $n;
    }
    return 9;
  }

  /**
   * 値の配列をレコードにする
   *
   * @param array $values
   * @return string
   */
  public static function encode(array $values): string {
    $head = '';
    $body = '';
    foreach ($values as $v) {
      if ($v === null) {
        $head .= "\0";
      } else if (is_int($v)) {
        if ($v === 0) {
          $head .= "\x08";
        } else if ($v === 1) {
          $head .= "\x09";
        } else if ($v >= -128 && $v <= 127) {
          $head .= "\x01";
          $body .= chr($v & 0xFF);
        } else if ($v >= -32768 && $v <= 32767) {
          $head .= "\x02";
          $body .= pack('n', $v & 0xFFFF);
        } else if ($v >= -8388608 && $v <= 8388607) {
          $head .= "\x03";
          $body .= substr(pack('N', $v & 0xFFFFFFFF), 1);
        } else if ($v >= -2147483648 && $v <= 2147483647) {
          $head .= "\x04";
          $body .= pack('N', $v & 0xFFFFFFFF);
        } else if ($v >= -140737488355328 && $v <= 140737488355327) {
          $head .= "\x05";
          $body .= substr(pack('J', $v), 2);
        } else {
          $head .= "\x06";
          $body .= pack('J', $v);
        }
      } else if (is_float($v)) {
        $head .= "\x07";
        $body .= pack('E', $v);
      } else if ($v instanceof Blob) {
        $head .= self::putVarint(strlen($v->data) * 2 + 12);
        $body .= $v->data;
      } else {
        $v = (string)$v;
        $head .= self::putVarint(strlen($v) * 2 + 13);
        $body .= $v;
      }
    }
    // ヘッダーの長さ（自分自身を含む）
    $n = strlen($head) + 1;
    if ($n >= 0x80) $n = strlen($head) + self::varintLen(strlen($head) + 2);
    return self::putVarint($n).$head.$body;
  }

  /**
   * レコードを値の配列にする
   *
   * @param string $rec
   * @return array
   */
  public static function decode(string $rec): array {
    $pos = 0;
    $hlen = self::getVarint($rec, $pos);
    $types = [];
    while ($pos < $hlen) $types[] = self::getVarint($rec, $pos);
    $pos = $hlen;
    $out = [];
    foreach ($types as $t) {
      switch ($t) {
        case 0:
          $out[] = null;
          break;
        case 1:
          $v = ord($rec[$pos] ?? "\0");
          $out[] = $v >= 0x80 ? $v - 0x100 : $v;
          $pos += 1;
          break;
        case 2:
          $v = unpack('n', $rec, $pos)[1];
          $out[] = $v >= 0x8000 ? $v - 0x10000 : $v;
          $pos += 2;
          break;
        case 3:
          $v = unpack('N', "\0".substr($rec, $pos, 3))[1];
          $out[] = $v >= 0x800000 ? $v - 0x1000000 : $v;
          $pos += 3;
          break;
        case 4:
          $v = unpack('N', $rec, $pos)[1];
          $out[] = $v >= 0x80000000 ? $v - 0x100000000 : $v;
          $pos += 4;
          break;
        case 5:
          $v = unpack('J', "\0\0".substr($rec, $pos, 6))[1];
          $out[] = $v >= 0x800000000000 ? $v - 0x1000000000000 : $v;
          $pos += 6;
          break;
        case 6:
          $out[] = unpack('J', $rec, $pos)[1];
          $pos += 8;
          break;
        case 7:
          $out[] = unpack('E', $rec, $pos)[1];
          $pos += 8;
          break;
        case 8:
          $out[] = 0;
          break;
        case 9:
          $out[] = 1;
          break;
        default:
          if ($t < 12) throw new \UnexpectedValueException("SQLite：不正なシリアル型：{$t}");
          $len = ($t - 12) >> 1;
          $s = (string)substr($rec, $pos, $len);
          $out[] = ($t & 1) ? $s : new Blob($s);
          $pos += $len;
      }
    }
    return $out;
  }

  /**
   * 値の種類の順番（NULL＜数値＜TEXT＜BLOB）
   */
  public static function typeClass(mixed $v): int {
    if ($v === null) return 0;
    if (is_int($v) || is_float($v)) return 1;
    if ($v instanceof Blob) return 3;
    return 2;
  }

  /**
   * 2つの値を比べる（SQLiteの順番）
   *
   * @param mixed $a
   * @param mixed $b
   * @param string $coll  照合順序：BINARY、NOCASE、RTRIM
   * @return int  -1、0、1
   */
  public static function compare(mixed $a, mixed $b, string $coll = 'BINARY'): int {
    $ta = self::typeClass($a);
    $tb = self::typeClass($b);
    if ($ta !== $tb) return $ta <=> $tb;
    switch ($ta) {
      case 0:
        return 0;
      case 1:
        if (is_int($a) && is_int($b)) return $a <=> $b;
        // 大きい整数と浮動小数点数
        if (is_int($a) && is_float($b) && is_finite($b) && abs($b) < 9.2e18) {
          $fb = (int)floor($b);
          return $a === $fb ? ($b > $fb ? -1 : 0) : ($a <=> $fb);
        }
        if (is_float($a) && is_int($b) && is_finite($a) && abs($a) < 9.2e18) {
          $fa = (int)floor($a);
          return $fa === $b ? ($a > $fa ? 1 : 0) : ($fa <=> $b);
        }
        if (is_nan($a) || is_nan($b)) return is_nan($a) <=> is_nan($b);
        return $a <=> $b;
      case 2:
        return self::compareText((string)$a, (string)$b, $coll);
      default:
        $c = strcmp($a->data, $b->data);
        return $c < 0 ? -1 : ($c > 0 ? 1 : 0);
    }
  }

  public static function compareText(string $a, string $b, string $coll): int {
    if ($coll === 'NOCASE') {
      $a = strtolower($a);
      $b = strtolower($b);
    } else if ($coll === 'RTRIM') {
      $a = rtrim($a, ' ');
      $b = rtrim($b, ' ');
    }
    $c = strcmp($a, $b);
    return $c < 0 ? -1 : ($c > 0 ? 1 : 0);
  }

  /**
   * インデックスのキーを比べる
   *
   * @param array $a  キー（列の値…、rowid）
   * @param array $b  比べるキー（短ければ、その分だけ比べる）
   * @param array $colls  列毎の照合順序
   * @param array $desc  列毎の降順
   * @return int
   */
  public static function compareKeys(array $a, array $b, array $colls, array $desc): int {
    $n = min(count($a), count($b));
    for ($i = 0; $i < $n; $i++) {
      $x = $a[$i];
      $y = $b[$i];
      // よく有る場合を先に
      if (is_int($x) && is_int($y)) {
        $c = $x <=> $y;
      } else if (is_string($x) && is_string($y) && ($colls[$i] ?? 'BINARY') === 'BINARY') {
        $c = strcmp($x, $y);
        $c = $c < 0 ? -1 : ($c > 0 ? 1 : 0);
      } else {
        $c = self::compare($x, $y, $colls[$i] ?? 'BINARY');
      }
      if ($c !== 0) return !empty($desc[$i]) ? -$c : $c;
    }
    return 0;
  }
}