<?php

/**
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the LGPL. For more information please see
 * <http://phing.info>.
 *
 * @version SVN: $Id: PgsqlPDOQuerySplitter.php 1274 2011-08-17 13:38:07Z mrook $
 * @package phing.tasks.ext.pdo
 */

require_once 'phing/tasks/ext/pdo/PDOQuerySplitter.php';

/**
 * Splits PostgreSQL's dialect of SQL into separate queries
 *
 * Unlike DefaultPDOQuerySplitter this uses a lexer instead of regular
 * expressions. This allows handling complex constructs like C-style comments
 * (including nested ones) and dollar-quoted strings.
 * 
 * @author  Alexey Borzov <avb@php.net>
 * @package phing.tasks.ext.pdo
 * @version $Revision: 1274 $
 * @link    http://www.phing.info/trac/ticket/499
 * @link    http://www.postgresql.org/docs/current/interactive/sql-syntax-lexical.html#SQL-SYNTAX-DOLLAR-QUOTING
 */
class PgsqlPDOQuerySplitter extends PDOQuerySplitter
{
   /**#@+
    * Lexer states
    */
    const STATE_NORMAL            = 0;
    const STATE_SINGLE_QUOTED     = 1;
    const STATE_DOUBLE_QUOTED     = 2;
    const STATE_DOLLAR_QUOTED     = 3;
    const STATE_COMMENT_LINEEND   = 4;
    const STATE_COMMENT_MULTILINE = 5;
    const STATE_BACKSLASH         = 6;
   /**#@-*/

   /**
    * Nesting depth of current multiline comment
    * @var int
    */
    protected $commentDepth = 0;

   /**
    * Current dollar-quoting "tag"
    * @var string
    */
    protected $quotingTag = '';

   /**
    * Current lexer state, one of STATE_* constants
    * @var int
    */
    protected $state = self::STATE_NORMAL;

   /**
    * Whether a backslash was just encountered in quoted string
    * @var bool
    */
    protected $escape = false;

   /**
    * Current source line being examined
    * @var string
    */
    protected $line = '';

   /**
    * Position in current source line
    * @var int
    */
    protected $inputIndex;

   /**
    * Gets next symbol from the input, false if at end
    *
    * @return string|bool
    */
    public function getc()
    {
        if (!strlen($this->line) || $this->inputIndex >= strlen($this->line)) {
            if (null === ($line = $this->sqlReader->readLine())) {
                return false;
            }
            $project    = $this->parent->getOwningTarget()->getProject();
            $this->line = ProjectConfigurator::replaceProperties(
                             $project, $line, $project->getProperties()
                          ) . "\n";
            $this->inputIndex = 0;
        }
        return $this->line[$this->inputIndex++];
    }

   /**
    * Bactracks one symbol on the input
    *
    * NB: we don't need ungetc() at the start of the line, so this case is
    * not handled. 
    */
    public function ungetc()
    {
        $this->inputIndex--;
    }

   /**
    * Checks whether symbols after $ are a valid dollar-quoting tag
    *
    * @return string|bool   Dollar-quoting "tag" if it is present, false otherwise
    */
    protected function checkDollarQuote()
    {
        $ch = $this->getc();
        if ('$' == $ch) {
            // empty tag
            return '';

        } elseif (!ctype_alpha($ch) && '_' != $ch) {
            // not a delimiter
            $this->ungetc();
            return false;

        } else {
            $tag = $ch;
            while (false !== ($ch = $this->getc())) {
                if ('$' == $ch) {
                    return $tag;

                } elseif (ctype_alnum($ch) || '_' == $ch) {
                    $tag .= $ch;

                } else {
                    for ($i = 0; $i < strlen($tag); $i++) {
                        $this->ungetc();
                    }
                    return false;
                }
            }
        }
    }
    
    public function nextQuery()
    {
        $sql       = '';
        $delimiter = $this->parent->getDelimiter();

        while (false !== ($ch = $this->getc())) {
            switch ($this->state) {
            case self::STATE_NORMAL:
                switch ($ch) {
                case '-':
                    if ('-' == $this->getc()) {
                        $this->state = self::STATE_COMMENT_LINEEND;
                    } else {
                        $this->ungetc();
                    }
                    break;
                case '"':
                    $this->state = self::STATE_DOUBLE_QUOTED;
                    break;
                case "'":
                    $this->state = self::STATE_SINGLE_QUOTED;
                    break;
                case '/':
                    if ('*' == $this->getc()) {
                        $this->state        = self::STATE_COMMENT_MULTILINE;
                        $this->commentDepth = 1;
                    } else {
                        $this->ungetc();
                    }
                    break;
                case '$':
                    if (false !== ($tag = $this->checkDollarQuote())) {
                        $this->state       = self::STATE_DOLLAR_QUOTED;
                        $this->quotingTag  = $tag;
                        $sql              .= '$' . $tag . '$';
                        continue 3;
                    }
                    break;
                // technically we can use e.g. psql's \g command as delimiter
                case $delimiter[0]:
                    $hasQuery = true;
                    for ($i = 1; $i < strlen($delimiter); $i++) {
                        if ($delimiter[$i] != $this->getc()) {
                            $hasQuery = false;
                        }
                    }
                    if ($hasQuery) {
                        return $sql;
                    } else {
                        for ($j = 1; $j < $i; $j++) {
                            $this->ungetc();
                        }
                    }
                }
                break;

            case self::STATE_COMMENT_LINEEND:
                if ("\n" == $ch) {
                    $this->state = self::STATE_NORMAL;
                }
                break;

            case self::STATE_COMMENT_MULTILINE:
                switch ($ch) {
                case '/':
                    if ('*' != $this->getc()) {
                        $this->ungetc();
                    } else {
                        $this->commentDepth++;
                    }
                    break;

                case '*':
                    if ('/' != $this->getc()) {
                        $this->ungetc();
                    } else {
                        $this->commentDepth--;
                        if (0 == $this->commentDepth) {
                            $this->state = self::STATE_NORMAL;
                            continue 3;
                        }
                    }
                }

            case self::STATE_SINGLE_QUOTED:
            case self::STATE_DOUBLE_QUOTED:
                if ($this->escape) {
                    $this->escape = false;
                    break;
                }
                $quote = $this->state == self::STATE_SINGLE_QUOTED ? "'" : '"';
                switch ($ch) {
                    case '\\':
                        $this->escape = true;
                        break;
                    case $quote:
                        if ($quote == $this->getc()) {
                            $sql .= $quote;
                        } else {
                            $this->ungetc();
                            $this->state = self::STATE_NORMAL;
                        }
                }

            case self::STATE_DOLLAR_QUOTED:
                if ('$' == $ch && false !== ($tag = $this->checkDollarQuote())) {
                    if ($tag == $this->quotingTag) {
                        $this->state = self::STATE_NORMAL;
                    }
                    $sql .= '$' . $tag . '$';
                    continue 2;
                }
            }

            if ($this->state != self::STATE_COMMENT_LINEEND && $this->state != self::STATE_COMMENT_MULTILINE) {
                $sql .= $ch;
            }
        }
        if ('' !== $sql) {
            return $sql;
        }
        return null;
    }
}
