<?php

namespace CodeInspector;

use CodeInspector\Issue\UndefinedMethod;
use CodeInspector\Issue\InaccessibleMethod;
use CodeInspector\Issue\InvalidReturnType;
use CodeInspector\Issue\InvalidDocblock;
use PhpParser;

class ClassMethodChecker extends FunctionChecker
{
    protected static $_method_comments = [];
    protected static $_method_files = [];
    protected static $_method_params = [];
    protected static $_method_namespaces = [];
    protected static $_method_return_types = [];
    protected static $_static_methods = [];
    protected static $_declaring_classes = [];
    protected static $_existing_methods = [];
    protected static $_have_reflected = [];
    protected static $_have_registered = [];
    protected static $_inherited_methods = [];
    protected static $_declaring_class = [];
    protected static $_method_visibility = [];
    protected static $_new_docblocks = [];

    const VISIBILITY_PUBLIC = 1;
    const VISIBILITY_PROTECTED = 2;
    const VISIBILITY_PRIVATE = 3;

    public function __construct(PhpParser\Node\FunctionLike $function, StatementsSource $source, array $this_vars = [])
    {
        parent::__construct($function, $source);

        if ($function instanceof PhpParser\Node\Stmt\ClassMethod) {
            $this->_registerMethod($function);
            $this->_is_static = $function->isStatic();
        }
    }

    /**
     * @return false|null
     */
    public function checkReturnTypes($update_doc_comment = false)
    {
        if (!$this->_function->stmts) {
            return;
        }

        if ($this->_function->name === '__construct') {
            // we know that constructors always return this
            return;
        }

        if (!isset(self::$_new_docblocks[$this->_file_name])) {
            self::$_new_docblocks[$this->_file_name] = [];
        }

        $method_id = $this->_absolute_class . '::' . $this->_function->name;

        // passing it through fleshOutReturnTypes eradicates errant $ vars
        $declared_return_type = StatementsChecker::fleshOutReturnTypes(
            self::getMethodReturnTypes($method_id),
            [],
            $method_id
        );

        if ($declared_return_type) {
            $inferred_return_types = EffectsAnalyser::getReturnTypes($this->_function->stmts, true);

            if (!$inferred_return_types) {
                if ($declared_return_type->isVoid()) {
                    return;
                }

                if (ScopeChecker::onlyThrows($this->_function->stmts)) {
                    // if there's a single throw statement, it's presumably an exception saying this method is not to be used
                    return;
                }

                if (IssueBuffer::accepts(
                    new InvalidReturnType(
                        'No return type was found for method ' . $method_id . ' but return type \'' . $declared_return_type . '\' was expected',
                        $this->_file_name,
                        $this->_function->getLine()
                    )
                )) {
                    return false;
                }

                return;
            }

            $inferred_return_type = Type::combineTypes($inferred_return_types);

            if ($inferred_return_type && !$inferred_return_type->isMixed() && !$declared_return_type->isMixed()) {
                if ($inferred_return_type->isNull() && $declared_return_type->isVoid()) {
                    return;
                }

                $simple_declared_return_types = array_map(
                    function ($return_type) {
                        return $return_type->value;
                    },
                    $declared_return_type->types
                );

                $simple_inferred_return_types = array_map(
                    function ($return_type) {
                        return $return_type->value;
                    },
                    $inferred_return_type->types
                );

                // gets elements A△B
                $differing_types = array_diff($simple_inferred_return_types, $simple_declared_return_types);

                if (count($differing_types) && (string) $inferred_return_type !== (string) $declared_return_type) {
                    // check whether the differing types are subclasses of declared return types
                    $truly_different = false;
                    foreach ($differing_types as $differing_type) {
                        $is_match = false;

                        foreach ($simple_declared_return_types as $simple_declared_return_type) {
                            if (is_subclass_of($differing_type, $simple_declared_return_type) ||
                                (in_array($differing_type, ['float', 'double', 'int']) && in_array($simple_declared_return_type, ['float', 'double', 'int'])) ||
                                (in_array($differing_type, ['boolean', 'bool']) && in_array($simple_declared_return_type, ['boolean', 'bool']))
                            ) {
                                $is_match = true;
                                break;
                            }
                        }

                        if (!$is_match) {
                            $truly_different = true;
                        }
                    }

                    if ($truly_different) {
                        if ($inferred_return_type->isNull()) {
                            $inferred_return_type = Type::getVoid();
                        }

                        if (IssueBuffer::accepts(
                            new InvalidReturnType(
                                'The given return type \'' . $declared_return_type . '\' for ' . $method_id . ' is incorrect, got \'' . $inferred_return_type . '\'',
                                $this->_file_name,
                                $this->_function->getLine()
                            )
                        )) {
                            return false;
                        }
                    }
                }
            }

            return;
        }
    }

    public static function getMethodParams($method_id)
    {
        self::_populateData($method_id);

        return self::$_method_params[$method_id];
    }

    public static function getMethodReturnTypes($method_id)
    {
        self::_populateData($method_id);

        return self::$_method_return_types[$method_id] ? clone self::$_method_return_types[$method_id] : null;
    }

    /**
     * @return void
     */
    public static function extractReflectionMethodInfo($method_id)
    {
        if (isset(self::$_have_reflected[$method_id]) || isset(self::$_have_registered[$method_id])) {
            return;
        }

        try {
            $method = new \ReflectionMethod($method_id);
        }
        catch (\ReflectionException $e) {
            // maybe it's an old-timey constructor

            $absolute_class = explode('::', $method_id)[0];
            $class_name = array_pop(explode('\\', $absolute_class));

            $alt_method_id = $absolute_class . '::' . $class_name;

            $method = new \ReflectionMethod($alt_method_id);
        }

        self::$_have_reflected[$method_id] = true;

        self::$_static_methods[$method_id] = $method->isStatic();
        self::$_method_files[$method_id] = $method->getFileName();
        self::$_method_namespaces[$method_id] = $method->getDeclaringClass()->getNamespaceName();
        self::$_declaring_classes[$method_id] = $method->getDeclaringClass()->name . '::' . $method->getName();
        self::$_method_visibility[$method_id] = $method->isPrivate() ?
                                                    self::VISIBILITY_PRIVATE :
                                                    ($method->isProtected() ? self::VISIBILITY_PROTECTED : self::VISIBILITY_PUBLIC);

        $params = $method->getParameters();

        $method_param_names = [];
        $method_param_types = [];

        self::$_method_params[$method_id] = [];
        foreach ($params as $param) {
            $param_type_string = null;

            if ($param->isArray()) {
                $param_type_string = 'array';

            }
            else {
                $param_class = null;

                try {
                    $param_class = $param->getClass();
                }
                catch (\ReflectionException $e) {
                    // do nothing
                }

                if ($param_class && self::$_method_files[$method_id]) {
                    $param_type_string = $param->getClass()->getName();
                }
            }

            $is_nullable = false;

            try {
                $is_nullable = $param->getDefaultValue() === null;

                if ($param_type_string && $is_nullable) {
                    $param_type_string .= '|null';
                }
            }
            catch (\ReflectionException $e) {
                // do nothing
            }

            $param_name = $param->getName();
            $param_type = $param_type_string ? Type::parseString($param_type_string) : Type::getMixed();

            $method_param_names[$param_name] = true;
            $method_param_types[$param_name] = $param_type;

            self::$_method_params[$method_id][] = [
                'name' => $param_name,
                'by_ref' => $param->isPassedByReference(),
                'type' => $param_type,
                'is_nullable' => $is_nullable
            ];
        }

        $return_types = null;

        $config = Config::getInstance();

        $return_type = null;

        if ($config->use_docblock_types) {
            $docblock_info = CommentChecker::extractDocblockInfo($method->getDocComment());

            if ($docblock_info['return_type']) {
                $return_type = Type::parseString(
                    self::_fixUpReturnType($docblock_info['return_type'], $method_id)
                );
            }

            if ($docblock_info['params']) {
                foreach ($docblock_info['params'] as $docblock_param) {
                    $docblock_param_name = $docblock_param['name'];

                    if (isset($method_param_names[$param_name])) {
                        foreach (self::$_method_params[$method_id] as &$param_info) {
                            if ($param_info['name'] === $docblock_param_name) {
                                $docblock_param_type_string = $docblock_param['type'];

                                $existing_param_type = $param_info['type'];

                                $new_param_type = Type::parseString(
                                    self::_fixUpReturnType($docblock_param_type_string, $method_id)
                                );

                                // only fix the type if we're dealing with an undefined or generic type
                                if ($existing_param_type->isMixed() || $new_param_type->hasGeneric()) {
                                    $existing_param_type_nullable = $param_info['is_nullable'];

                                    if ($existing_param_type_nullable && !$new_param_type->isNullable()) {
                                        $new_param_type->types['null'] = Type::getNull(false);
                                    }

                                    $param_info['type'] = $new_param_type;
                                }

                            }
                        }
                    }
                }
            }
        }

        self::$_method_return_types[$method_id] = $return_type;
    }

    protected static function _copyToChildMethod($method_id, $child_method_id)
    {
        if (!isset(self::$_have_registered[$method_id]) && !isset(self::$_have_reflected[$method_id])) {
            self::extractReflectionMethodInfo($method_id);
        }

        if (self::$_method_visibility[$method_id] !== self::VISIBILITY_PRIVATE) {
            self::$_method_files[$child_method_id] = self::$_method_files[$method_id];
            self::$_method_params[$child_method_id] = self::$_method_params[$method_id];
            self::$_method_namespaces[$child_method_id] = self::$_method_namespaces[$method_id];
            self::$_method_return_types[$child_method_id] = self::$_method_return_types[$method_id];
            self::$_static_methods[$child_method_id] = self::$_static_methods[$method_id];
            self::$_method_visibility[$child_method_id] = self::$_method_visibility[$method_id];

            self::$_declaring_classes[$child_method_id] = self::$_declaring_classes[$method_id];
            self::$_existing_methods[$child_method_id] = 1;
        }
    }

    /**
     * Determines whether a given method is static or not
     * @param  string  $method_id
     * @return bool
     */
    public static function isGivenMethodStatic($method_id)
    {
        self::_populateData($method_id);

        return self::$_static_methods[$method_id];
    }

    protected function _registerMethod(PhpParser\Node\Stmt\ClassMethod $method)
    {
        $method_id = $this->_absolute_class . '::' . $method->name;

        if (isset(self::$_have_reflected[$method_id]) || isset(self::$_have_registered[$method_id])) {
            return;
        }

        self::$_have_registered[$method_id] = true;

        self::$_declaring_classes[$method_id] = $method_id;
        self::$_static_methods[$method_id] = $method->isStatic();
        self::$_method_comments[$method_id] = $method->getDocComment() ?: '';

        self::$_method_namespaces[$method_id] = $this->_namespace;
        self::$_method_files[$method_id] = $this->_file_name;
        self::$_existing_methods[$method_id] = 1;

        if ($method->isPrivate()) {
            self::$_method_visibility[$method_id] = self::VISIBILITY_PRIVATE;
        }
        elseif ($method->isProtected()) {
            self::$_method_visibility[$method_id] = self::VISIBILITY_PROTECTED;
        }
        else {
            self::$_method_visibility[$method_id] = self::VISIBILITY_PUBLIC;
        }

        self::$_method_params[$method_id] = [];

        $method_param_names = [];

        foreach ($method->getParams() as $param) {
            $param_type = null;

            if ($param->type) {
                if ($param->type instanceof Type) {
                    $param_type = $param_type;
                }
                else {
                    if (is_string($param->type)) {
                        $param_type_string = $param->type;
                    }
                    elseif ($param->type instanceof PhpParser\Node\Name\FullyQualified) {
                        $param_type_string = implode('\\', $param->type->parts);
                    }
                    elseif ($param->type->parts === ['self']) {
                        $param_type_string = $this->_absolute_class;
                    }
                    else {
                        $param_type_string = ClassChecker::getAbsoluteClassFromString(implode('\\', $param->type->parts), $this->_namespace, $this->_aliased_classes);
                    }

                    $is_nullable = $param->default !== null &&
                            $param->default instanceof \PhpParser\Node\Expr\ConstFetch &&
                            $param->default->name instanceof PhpParser\Node\Name &&
                            $param->default->name->parts = ['null'];

                    if ($param_type_string) {
                        if ($is_nullable) {
                            $param_type_string .= '|null';
                        }

                        $param_type = Type::parseString($param_type_string);
                    }
                }
            }

            $method_param_names[$param->name] = $param_type;

            self::$_method_params[$method_id][] = [
                'name' => $param->name,
                'by_ref' => $param->byRef,
                'type' => $param_type ?: Type::getMixed(),
            ];
        }

        $config = Config::getInstance();
        $return_type = null;

        if ($config->use_docblock_types) {
            $docblock_info = CommentChecker::extractDocblockInfo($method->getDocComment());

            if ($docblock_info['return_type']) {
                $return_type =
                    Type::parseString(
                        $this->fixUpLocalType(
                            $docblock_info['return_type'],
                            $this->_absolute_class,
                            $this->_namespace,
                            $this->_aliased_classes
                        )
                    );
            }

            if ($docblock_info['params']) {
                foreach ($docblock_info['params'] as $docblock_param) {
                    $param_name = $docblock_param['name'];

                    if (!array_key_exists($param_name, $method_param_names)) {
                        if (IssueBuffer::accepts(
                            new InvalidDocblock('Parameter $' . $param_name .' does not appear in the argument list for ' . $method_id, $this->_file_name, $method->getLine())
                        )) {
                            return false;
                        }

                        continue;
                    }

                    $param_type =
                        Type::parseString(
                            $this->fixUpLocalType(
                                $docblock_param['type'],
                                $this->_absolute_class,
                                $this->_namespace,
                                $this->_aliased_classes
                            )
                        );

                    if ($method_param_names[$param_name] && !$method_param_names[$param_name]->isMixed()) {
                        if (!$param_type->isIn($method_param_names[$param_name])) {
                            if (IssueBuffer::accepts(
                                new InvalidDocblock(
                                    'Parameter $' . $param_name .' has wrong type \'' . $param_type . '\', should be \'' . $method_param_names[$param_name] . '\'',
                                    $this->_file_name,
                                    $method->getLine()
                                )
                            )) {
                                return false;
                            }

                            continue;
                        }
                    }
                }
            }
        }

        self::$_method_return_types[$method_id] = $return_type;
    }

    public static function fixUpLocalType($return_type, $absolute_class, $namespace, $aliased_classes)
    {
        if (strpos($return_type, '[') !== false) {
            $return_type = Type::convertSquareBrackets($return_type);
        }

        $return_type_tokens = Type::tokenize($return_type);

        foreach ($return_type_tokens as &$return_type_token) {
            if ($return_type_token[0] === '\\') {
                $return_type_token = substr($return_type_token, 1);
                continue;
            }

            if (in_array($return_type_token, ['<', '>', '|'])) {
                continue;
            }

            $return_type_token = Type::fixScalarTerms($return_type_token);

            if ($return_type_token[0] === strtoupper($return_type_token[0])) {
                if ($return_type === '$this' && $absolute_class) {
                    $return_type_token = $absolute_class;
                    continue;
                }

                $return_type_token = ClassChecker::getAbsoluteClassFromString($return_type_token, $namespace, $aliased_classes);
            }
        }

        return implode('', $return_type_tokens);
    }

    protected static function _fixUpReturnType($return_type, $method_id)
    {
        if (strpos($return_type, '[') !== false) {
            $return_type = Type::convertSquareBrackets($return_type);
        }

        $return_type_tokens = Type::tokenize($return_type);

        foreach ($return_type_tokens as &$return_type_token) {
            if ($return_type_token[0] === '\\') {
                $return_type_token = substr($return_type_token, 1);
                continue;
            }

            if (in_array($return_type_token, ['<', '>', '|'])) {
                continue;
            }

            $return_type_token = Type::fixScalarTerms($return_type_token);

            if ($return_type_token[0] === strtoupper($return_type_token[0])) {
                $absolute_class = explode('::', $method_id)[0];

                if ($return_type_token === '$this') {
                    $return_type_token = $absolute_class;
                    continue;
                }

                $return_type_token = FileChecker::getAbsoluteClassFromNameInFile($return_type_token, self::$_method_namespaces[$method_id], self::$_method_files[$method_id]);
            }
        }

        return implode('', $return_type_tokens);
    }

    /**
     * @return false|null
     */
    public static function checkMethodExists($method_id, $file_name, $stmt)
    {
        if (isset(self::$_existing_methods[$method_id])) {
            return;
        }

        $method_parts = explode('::', $method_id);

        if (method_exists($method_parts[0], $method_parts[1])) {
            self::$_existing_methods[$method_id] = 1;
            return;
        }

        if (IssueBuffer::accepts(
            new UndefinedMethod('Method ' . $method_id . ' does not exist', $file_name, $stmt->getLine())
        )) {
            return false;
        }
    }

    protected static function _populateData($method_id)
    {
        if (!isset(self::$_have_reflected[$method_id]) && !isset(self::$_have_registered[$method_id])) {
            if (isset(self::$_inherited_methods[$method_id])) {
                self::_copyToChildMethod(self::$_inherited_methods[$method_id], $method_id);
            }
            else {
                self::extractReflectionMethodInfo($method_id);
            }
        }
    }

    /**
     * @return false|null
     */
    public static function checkMethodVisibility($method_id, $calling_context, $file_name, $line_number)
    {
        self::_populateData($method_id);

        $method_class = explode('::', $method_id)[0];
        $method_name = explode('::', $method_id)[1];

        if (!isset(self::$_method_visibility[$method_id])) {
            if (IssueBuffer::accepts(
                new InaccessibleMethod('Cannot access method ' . $method_id, $file_name, $line_number)
            )) {
                return false;
            }
        }

        switch (self::$_method_visibility[$method_id]) {
            case self::VISIBILITY_PUBLIC:
                return;

            case self::VISIBILITY_PRIVATE:
                if (!$calling_context || $method_class !== $calling_context) {
                    if (IssueBuffer::accepts(
                        new InaccessibleMethod('Cannot access private method ' . $method_id . ' from context ' . $calling_context, $file_name, $line_number)
                    )) {
                        return false;
                    }
                }
                return;

            case self::VISIBILITY_PROTECTED:
                if ($method_class === $calling_context) {
                    return;
                }

                if (!$calling_context) {
                    if (IssueBuffer::accepts(
                        new InaccessibleMethod('Cannot access protected method ' . $method_id, $file_name, $line_number)
                    )) {
                        return false;
                    }
                }

                if (is_subclass_of($method_class, $calling_context) && method_exists($calling_context, $method_name)) {
                    return;
                }

                if (!is_subclass_of($calling_context, $method_class)) {
                    if (IssueBuffer::accepts(
                        new InaccessibleMethod('Cannot access protected method ' . $method_id . ' from context ' . $calling_context, $file_name, $line_number)
                    )) {
                        return false;
                    }
                }
        }
    }

    public static function registerInheritedMethod($parent_method_id, $method_id)
    {
        // only register the method if it's not already there
        if (!isset(self::$_declaring_classes[$method_id])) {
            self::$_declaring_classes[$method_id] = $parent_method_id;
        }

        self::$_inherited_methods[$method_id] = $parent_method_id;
    }

    public static function getDeclaringMethod($method_id)
    {
        if (isset(self::$_declaring_classes[$method_id])) {
            return self::$_declaring_classes[$method_id];
        }

        $method_name = explode('::', $method_id)[1];

        $parent_method_id = (new \ReflectionMethod($method_id))->getDeclaringClass()->getName() . '::' . $method_name;

        self::$_declaring_classes[$method_id] = $parent_method_id;

        return $parent_method_id;
    }

    public static function getNewDocblocksForFile($file_name)
    {
        return isset(self::$_new_docblocks[$file_name]) ? self::$_new_docblocks[$file_name] : [];
    }

    public static function clearCache()
    {
        self::$_method_comments = [];
        self::$_method_files = [];
        self::$_method_params = [];
        self::$_method_namespaces = [];
        self::$_method_return_types = [];
        self::$_static_methods = [];
        self::$_declaring_classes = [];
        self::$_existing_methods = [];
        self::$_have_reflected = [];
        self::$_have_registered = [];
        self::$_inherited_methods = [];
        self::$_declaring_class = [];
        self::$_method_visibility = [];
        self::$_new_docblocks = [];
    }
}