#!/usr/bin/env php
<?php

// We have to do this first before we load any symbols, because we define the
// built-in symbol list through introspection.
$builtins = phutil_symbols_get_builtins();

$root = dirname(dirname(dirname(__FILE__)));
require_once $root.'/support/init/init-script.php';

$args = new PhutilArgumentParser($argv);
$args->setTagline(pht('identify symbols in a PHP source file'));
$args->setSynopsis(<<<EOHELP
    **extract-symbols.php** [__options__] __path.php__
        Identify the symbols (clases, functions and interfaces) in a PHP
        source file. Symbols are divided into "have" symbols (symbols the file
        declares) and "need" symbols (symbols the file depends on). For example,
        class declarations are "have" symbols, while object instantiations
        with "new X()" are "need" symbols.

        Dependencies on builtins and symbols marked '@phutil-external-symbol'
        in docblocks are omitted without __--all__.

        Symbols are reported in JSON on stdout.

        This script is used internally by Arcanist to build maps of library
        symbols.

        It would be nice to eventually implement this as a C++ xhpast binary,
        as it's relatively stable and performance is currently awful
        (500ms+ for moderately large files).

EOHELP
);
$args->parseStandardArguments();
$args->parse(
  array(
    array(
      'name'      => 'all',
      'help'      => pht(
        'Emit all symbols, including built-ins and declared externals.'),
    ),
    array(
      'name' => 'builtins',
      'help' => pht('Emit builtin symbols.'),
    ),
    array(
      'name'      => 'ugly',
      'help'      => pht('Do not prettify JSON output.'),
    ),
    array(
      'name'      => 'path',
      'wildcard'  => true,
      'help'      => pht('PHP Source file to analyze.'),
    ),
  ));

$paths = $args->getArg('path');

$show_all = $args->getArg('all');
$show_builtins = $args->getArg('builtins');

if ($show_all && $show_builtins) {
  throw new PhutilArgumentUsageException(
    pht(
      'Flags "--all" and "--builtins" are not compatible.'));
}

if ($show_builtins && $paths) {
  throw new PhutilArgumentUsageException(
    pht(
      'Flag "--builtins" may not be used with a path.'));
}

if ($show_builtins) {
  $path = '<builtins>';
  $source_code = '';
} else {
  if (count($paths) !== 1) {
    throw new Exception(pht('Specify exactly one path!'));
  }
  $path = Filesystem::resolvePath(head($paths));
  $source_code = Filesystem::readFile($path);
}

try {
  $tree = XHPASTTree::newFromData($source_code);
} catch (XHPASTSyntaxErrorException $ex) {
  $result = array(
    'error' => $ex->getMessage(),
    'line'  => $ex->getErrorLine(),
    'file'  => $path,
  );
  $json = new PhutilJSON();
  echo $json->encodeFormatted($result);
  exit(0);
}

$root = $tree->getRootNode();
$root->buildSelectCache();

// -(  Unsupported Constructs  )------------------------------------------------

$namespaces = $root->selectDescendantsOfType('n_NAMESPACE');
foreach ($namespaces as $namespace) {
  phutil_fail_on_unsupported_feature($namespace, $path, pht('namespaces'));
}

$uses = $root->selectDescendantsOfType('n_USE');
foreach ($namespaces as $namespace) {
  phutil_fail_on_unsupported_feature(
    $namespace, $path, pht('namespace `%s` statements', 'use'));
}

$possible_traits = $root->selectDescendantsOfType('n_CLASS_DECLARATION');
foreach ($possible_traits as $possible_trait) {
  $attributes = $possible_trait->getChildByIndex(0);
  // Can't use getChildByIndex here because not all classes have attributes
  foreach ($attributes->getChildren() as $attribute) {
    if (strtolower($attribute->getConcreteString()) === 'trait') {
      phutil_fail_on_unsupported_feature($possible_trait, $path, pht('traits'));
    }
  }
}


// -(  Marked Externals  )------------------------------------------------------


// Identify symbols marked with "@phutil-external-symbol", so we exclude them
// from the dependency list.

$externals = array();
$doc_parser = new PhutilDocblockParser();
foreach ($root->getTokens() as $token) {
  if ($token->getTypeName() === 'T_DOC_COMMENT') {
    list($block, $special) = $doc_parser->parse($token->getValue());

    $ext_list = idx($special, 'phutil-external-symbol');
    $ext_list = (array)$ext_list;
    $ext_list = array_filter($ext_list);

    foreach ($ext_list as $ext_ref) {
      $matches = null;
      if (preg_match('/^\s*(\S+)\s+(\S+)/', $ext_ref, $matches)) {
        $externals[$matches[1]][$matches[2]] = true;
      }
    }
  }
}


// -(  Declarations and Dependencies  )-----------------------------------------


// The first stage of analysis is to find all the symbols we declare in the
// file (like functions and classes) and all the symbols we use in the file
// (like calling functions and invoking classes). Later, we filter this list
// to exclude builtins.


$have = array();  // For symbols we declare.
$need = array();  // For symbols we use.
$xmap = array();  // For extended classes and implemented interfaces.


// -(  Functions  )-------------------------------------------------------------


// Find functions declared in this file.

// This is "function f() { ... }".
$functions = $root->selectDescendantsOfType('n_FUNCTION_DECLARATION');
foreach ($functions as $function) {
  $name = $function->getChildByIndex(2);
  if ($name->getTypeName() === 'n_EMPTY') {
    // This is an anonymous function; don't record it into the symbol
    // index.
    continue;
  }
  $have[] = array(
    'type'    => 'function',
    'symbol'  => $name,
  );
}


// Find functions used by this file. Uses:
//
//  - Explicit Call
//  - String literal passed to call_user_func() or call_user_func_array()
//  - String literal in array literal in call_user_func()/call_user_func_array()
//
// TODO: Possibly support these:
//
//  - String literal in ReflectionFunction().

// This is "f();".
$calls = $root->selectDescendantsOfType('n_FUNCTION_CALL');
foreach ($calls as $call) {
  $name = $call->getChildByIndex(0);
  if ($name->getTypeName() === 'n_VARIABLE' ||
      $name->getTypeName() === 'n_VARIABLE_VARIABLE') {
    // Ignore these, we can't analyze them.
    continue;
  }
  if ($name->getTypeName() === 'n_CLASS_STATIC_ACCESS') {
    // These are "C::f()", we'll pick this up later on.
    continue;
  }
  $call_name = $name->getConcreteString();
  if ($call_name === 'call_user_func' ||
      $call_name === 'call_user_func_array') {
    $params = $call->getChildByIndex(1)->getChildren();
    if (!count($params)) {
      // This is a bare call_user_func() with no arguments; just ignore it.
      continue;
    }
    $symbol = array_shift($params);
    $type = 'function';
    $symbol_value = $symbol->getStringLiteralValue();

    if ($symbol_value !== null) {
      $pos = strpos($symbol_value, '::');
    } else {
      $pos = false;
    }

    if ($pos) {
      $type = 'class';
      $symbol_value = substr($symbol_value, 0, $pos);
    } else if ($symbol->getTypeName() === 'n_ARRAY_LITERAL') {
      try {
        $type = 'class';
        $symbol_value = idx($symbol->evalStatic(), 0);
      } catch (Exception $ex) {}
    }
    if ($symbol_value && strpos($symbol_value, '$') === false) {
      $need[] = array(
        'type'    => $type,
        'name'    => $symbol_value,
        'symbol'  => $symbol,
      );
    }
  } else {
    $need[] = array(
      'type'    => 'function',
      'symbol'  => $name,
    );
  }
}


// -(  Classes  )---------------------------------------------------------------


// Find classes declared by this file.


// This is "class X ... { ... }".
$classes = $root->selectDescendantsOfType('n_CLASS_DECLARATION');
foreach ($classes as $class) {
  $class_name = $class->getChildByIndex(1);
  $have[] = array(
    'type'    => 'class',
    'symbol'  => $class_name,
  );
}


// Find classes used by this file. We identify these:
//
//  - class ... extends X
//  - new X
//  - Static method call
//  - Static property access
//  - Use of class constant
//  - typehints
//  - catch
//  - instanceof
//  - newv()
//
// TODO: Possibly support these:
//
//  - String literal in ReflectionClass().


// This is "class X ... { ... }".
$classes = $root->selectDescendantsOfType('n_CLASS_DECLARATION');
foreach ($classes as $class) {
  $class_name = $class->getChildByIndex(1)->getConcreteString();
  $extends = $class->getChildByIndex(2);
  foreach ($extends->selectDescendantsOfType('n_CLASS_NAME') as $parent) {
    $need[] = array(
      'type'    => 'class',
      'symbol'  => $parent,
    );

    // Track all 'extends' in the extension map.
    $xmap[$class_name][] = $parent->getConcreteString();
  }
}

// This is "new X()".
$uses_of_new = $root->selectDescendantsOfType('n_NEW');
foreach ($uses_of_new as $new_operator) {
  $name = $new_operator->getChildByIndex(0);
  if ($name->getTypeName() === 'n_VARIABLE' ||
      $name->getTypeName() === 'n_VARIABLE_VARIABLE') {
    continue;
  }
  $need[] = array(
    'type'    => 'class',
    'symbol'  => $name,
  );
}

// This covers all of "X::$y", "X::y()" and "X::CONST".
$static_uses = $root->selectDescendantsOfType('n_CLASS_STATIC_ACCESS');
foreach ($static_uses as $static_use) {
  $name = $static_use->getChildByIndex(0);
  if ($name->getTypeName() !== 'n_CLASS_NAME') {
    continue;
  }
  $need[] = array(
    'type'    => 'class',
    'symbol'  => $name,
  );
}

// This is "function (X $x)".
$parameters = $root->selectDescendantsOfType('n_DECLARATION_PARAMETER');
foreach ($parameters as $parameter) {
  $hint = $parameter->getChildByIndex(0);
  if ($hint->getTypeName() !== 'n_CLASS_NAME') {
    continue;
  }
  $need[] = array(
    'type'    => 'class/interface',
    'symbol'  => $hint,
  );
}

$returns = $root->selectDescendantsOfType('n_DECLARATION_RETURN');
foreach ($returns as $return) {
  $hint = $return->getChildByIndex(0);
  if ($hint->getTypeName() !== 'n_CLASS_NAME') {
    continue;
  }
  $need[] = array(
    'type'   => 'class/interface',
    'symbol' => $hint,
  );
}

// This is "catch (Exception $ex)".
$catches = $root->selectDescendantsOfType('n_CATCH');
foreach ($catches as $catch) {
  $need[] = array(
    'type'    => 'class/interface',
    'symbol'  => $catch->getChildOfType(0, 'n_CLASS_NAME'),
  );
}

// This is "$x instanceof X".
$instanceofs = $root->selectDescendantsOfType('n_BINARY_EXPRESSION');
foreach ($instanceofs as $instanceof) {
  $operator = $instanceof->getChildOfType(1, 'n_OPERATOR');
  if ($operator->getConcreteString() !== 'instanceof') {
    continue;
  }
  $class = $instanceof->getChildByIndex(2);
  if ($class->getTypeName() !== 'n_CLASS_NAME') {
    continue;
  }
  $need[] = array(
    'type'    => 'class/interface',
    'symbol'  => $class,
  );
}

// This is "newv('X')".
$calls = $root->selectDescendantsOfType('n_FUNCTION_CALL');
foreach ($calls as $call) {
  $call_name = $call->getChildByIndex(0)->getConcreteString();
  if ($call_name !== 'newv') {
    continue;
  }
  $params = $call->getChildByIndex(1)->getChildren();
  if (!count($params)) {
    continue;
  }
  $symbol = reset($params);
  $symbol_value = $symbol->getStringLiteralValue();
  if ($symbol_value && strpos($symbol_value, '$') === false) {
    $need[] = array(
      'type'    => 'class',
      'name'    => $symbol_value,
      'symbol'  => $symbol,
    );
  }
}


// -(  Interfaces  )------------------------------------------------------------


// Find interfaces declared in this file.


// This is "interface X .. { ... }".
$interfaces = $root->selectDescendantsOfType('n_INTERFACE_DECLARATION');
foreach ($interfaces as $interface) {
  $interface_name = $interface->getChildByIndex(1);
  $have[] = array(
    'type'    => 'interface',
    'symbol'  => $interface_name,
  );
}


// Find interfaces used by this file. We identify these:
//
//  - class ... implements X
//  - interface ... extends X


// This is "class X ... { ... }".
$classes = $root->selectDescendantsOfType('n_CLASS_DECLARATION');
foreach ($classes as $class) {
  $class_name = $class->getChildByIndex(1)->getConcreteString();
  $implements = $class->getChildByIndex(3);
  $interfaces = $implements->selectDescendantsOfType('n_CLASS_NAME');
  foreach ($interfaces as $interface) {
    $need[] = array(
      'type'    => 'interface',
      'symbol'  => $interface,
    );

    // Track 'class ... implements' in the extension map.
    $xmap[$class_name][] = $interface->getConcreteString();
  }
}


// This is "interface X ... { ... }".
$interfaces = $root->selectDescendantsOfType('n_INTERFACE_DECLARATION');
foreach ($interfaces as $interface) {
  $interface_name = $interface->getChildByIndex(1)->getConcreteString();

  $extends = $interface->getChildByIndex(2);
  foreach ($extends->selectDescendantsOfType('n_CLASS_NAME') as $parent) {
    $need[] = array(
      'type'    => 'interface',
      'symbol'  => $parent,
    );

    // Track 'interface ... extends' in the extension map.
    $xmap[$interface_name][] = $parent->getConcreteString();
  }
}


// -(  Analysis  )--------------------------------------------------------------


$declared_symbols = array();
foreach ($have as $key => $spec) {
  $name = $spec['symbol']->getConcreteString();
  $declared_symbols[$spec['type']][$name] = $spec['symbol']->getOffset();
}

$required_symbols = array();
foreach ($need as $key => $spec) {
  $name = idx($spec, 'name');
  if (!$name) {
    $name = $spec['symbol']->getConcreteString();
  }

  $type = $spec['type'];
  foreach (explode('/', $type) as $libtype) {
    if (!$show_all) {
      if (!empty($externals[$libtype][$name])) {
        // Ignore symbols declared as externals.
        continue 2;
      }
      if (!empty($builtins[$libtype][$name])) {
        // Ignore symbols declared as builtins.
        continue 2;
      }
    }
    if (!empty($declared_symbols[$libtype][$name])) {
      // We declare this symbol, so don't treat it as a requirement.
      continue 2;
    }
  }
  if (!empty($required_symbols[$type][$name])) {
    // Report only the first use of a symbol, since reporting all of them
    // isn't terribly informative.
    continue;
  }
  $required_symbols[$type][$name] = $spec['symbol']->getOffset();
}

if ($show_builtins) {
  foreach ($builtins as $type => $builtin_symbols) {
    foreach ($builtin_symbols as $builtin_symbol => $ignored) {
      $declared_symbols[$type][$builtin_symbol] = null;
    }
  }
}

$result = array(
  'have'  => $declared_symbols,
  'need'  => $required_symbols,
  'xmap'  => $xmap,
);


// -(  Output  )----------------------------------------------------------------


if ($args->getArg('ugly')) {
  echo json_encode($result);
} else {
  $json = new PhutilJSON();
  echo $json->encodeFormatted($result);
}


// -(  Library  )---------------------------------------------------------------

function phutil_fail_on_unsupported_feature(XHPASTNode $node, $file, $what) {
  $line = $node->getLineNumber();
  $message = phutil_console_wrap(
    pht(
      '`%s` has limited support for features introduced after PHP 5.2.3. '.
      'This library uses an unsupported feature (%s) on line %d of %s.',
      'arc liberate',
      $what,
      $line,
      Filesystem::readablePath($file)));

  $result = array(
    'error' => $message,
    'line'  => $line,
    'file'  => $file,
  );
  $json = new PhutilJSON();
  echo $json->encodeFormatted($result);
  exit(0);
}

function phutil_symbols_get_builtins() {
  $builtin = array();
  $builtin['classes']    = get_declared_classes();
  $builtin['interfaces'] = get_declared_interfaces();

  $funcs = get_defined_functions();
  $builtin['functions']  = $funcs['internal'];

  $compat = json_decode(
    file_get_contents(
      dirname(__FILE__).'/../../resources/php/symbol-information.json'),
    true);

  foreach (array('functions', 'classes', 'interfaces') as $type) {
    // Developers may not have every extension that a library potentially uses
    // installed. We supplement the list of declared functions and classes with
    // a list of known extension functions to avoid raising false positives just
    // because you don't have pcntl, etc.
    $extensions = array_keys($compat[$type]);
    $builtin[$type] = array_merge($builtin[$type], $extensions);
  }

  return array(
    'class'     => array_fill_keys($builtin['classes'], true) + array(
      'static' => true,
      'parent' => true,
      'self'   => true,

      // PHP7 defines these new parent classes of "Exception", but they do not
      // exist prior to PHP7. It's possible to use them safely in PHP5, in
      // some cases, to write code which is compatible with either PHP5 or
      // PHP7, but it's hard for us tell if a particular use is safe or not.
      // For now, assume users know what they're doing and that uses are safe.
      // For discussion, see T12855.
      'Throwable' => true,
      'Error' => true,
      'ParseError' => true,

      // PHP7 types.
      'bool' => true,
      'float' => true,
      'int' => true,
      'string' => true,
      'iterable' => true,
      'object' => true,
      'void' => true,
    ),
    'function'  => array_filter(
      array(
        'empty' => true,
        'isset' => true,
        'die'   => true,

        // HPHP/i defines these functions as 'internal', but they are NOT
        // builtins and do not exist in vanilla PHP. Make sure we don't mark
        // them as builtin since we need to add dependencies for them.
        'idx'   => false,
        'id'    => false,
      ) + array_fill_keys($builtin['functions'], true)),
    'interface' => array_fill_keys($builtin['interfaces'], true),
  );
}