<?php

declare(strict_types=1);

namespace ProxyManager\ProxyGenerator\Util;

use InvalidArgumentException;
use Laminas\Code\Generator\PropertyGenerator;

use function sprintf;
use function str_replace;
use function substr;
use function var_export;

/**
 * Generates code necessary to simulate a fatal error in case of unauthorized
 * access to class members in magic methods even when in child classes and dealing
 * with protected members.
 */
class PublicScopeSimulator
{
    public const OPERATION_SET   = 'set';
    public const OPERATION_GET   = 'get';
    public const OPERATION_ISSET = 'isset';
    public const OPERATION_UNSET = 'unset';

    /**
     * Generates code for simulating access to a property from the scope that is accessing a proxy.
     * This is done by introspecting `debug_backtrace()` and then binding a closure to the scope
     * of the parent caller.
     *
     * @param string            $operationType      operation to execute: one of 'get', 'set', 'isset' or 'unset'
     * @param string            $nameParameter      name of the `name` parameter of the magic method
     * @param string|null       $valueParameter     name of the `value` parameter of the magic method
     * @param PropertyGenerator $valueHolder        name of the property containing the target object from which
     *                                              to read the property. `$this` if none provided
     * @param string|null       $returnPropertyName name of the property to which we want to assign the result of
     *                                              the operation. Return directly if none provided
     * @param string|null       $interfaceName      name of the proxified interface if any
     *
     * @throws InvalidArgumentException
     */
    public static function getPublicAccessSimulationCode(
        string $operationType,
        string $nameParameter,
        ?string $valueParameter = null,
        ?PropertyGenerator $valueHolder = null,
        ?string $returnPropertyName = null,
        ?string $interfaceName = null
    ): string {
        $byRef  = self::getByRefReturnValue($operationType);
        $value  = $operationType === self::OPERATION_SET ? ', $' . ($valueParameter ?? 'value') : '';
        $target = '$this';

        if ($valueHolder) {
            $target = '$this->' . $valueHolder->getName();
        }

        if ($interfaceName !== null) {
            return '$targetObject = ' . $target . ';' . "\n\n"
                . self::getUndefinedPropertyNotice($operationType, $nameParameter, $interfaceName)
                . self::getOperation($operationType, $nameParameter, $valueParameter);
        }

        return '$realInstanceReflection = new \\ReflectionClass(get_parent_class($this));' . "\n\n"
            . 'if (! $realInstanceReflection->hasProperty($' . $nameParameter . ')) {' . "\n"
            . '    $targetObject = ' . $target . ';' . "\n\n"
            . self::getUndefinedPropertyNotice($operationType, $nameParameter)
            . '    ' . self::getOperation($operationType, $nameParameter, $valueParameter) . "\n"
            . "    return;\n"
            . '}' . "\n\n"
            . '$targetObject = ' . self::getTargetObject($valueHolder) . ";\n"
            . '$accessor = function ' . $byRef . '() use ($targetObject, $' . $nameParameter . $value . ') {' . "\n"
            . '    ' . self::getOperation($operationType, $nameParameter, $valueParameter) . "\n"
            . "};\n"
            . self::getScopeReBind()
            . (
                $returnPropertyName
                    ? '$' . $returnPropertyName . ' = ' . $byRef . '$accessor();'
                    : '$returnValue = ' . $byRef . '$accessor();' . "\n\n" . 'return $returnValue;'
            );
    }

    /**
     * This will generate code that triggers a notice if access is attempted on a non-existing property
     */
    private static function getUndefinedPropertyNotice(string $operationType, string $nameParameter, ?string $interfaceName = null): string
    {
        if ($operationType !== self::OPERATION_GET) {
            return '';
        }

        $code = '    $backtrace = debug_backtrace(false, 1);' . "\n"
            . '    trigger_error(' . "\n"
            . '        sprintf(' . "\n"
            . '            \'Undefined property: %s::$%s in %s on line %s\',' . "\n"
            . '            ' . ($interfaceName !== null ? var_export($interfaceName, true) : 'get_parent_class($this)') . ',' . "\n"
            . '            $' . $nameParameter . ',' . "\n"
            . '            $backtrace[0][\'file\'],' . "\n"
            . '            $backtrace[0][\'line\']' . "\n"
            . '        ),' . "\n"
            . '        \E_USER_NOTICE' . "\n"
            . '    );' . "\n";

        if ($interfaceName !== null) {
            $code = str_replace("\n    ", "\n", substr($code, 4));
        }

        return $code;
    }

    /**
     * Defines whether the given operation produces a reference.
     *
     * Note: if the object is a wrapper, the wrapped instance is accessed directly. If the object
     * is a ghost or the proxy has no wrapper, then an instance of the parent class is created via
     * on-the-fly unserialization
     */
    private static function getByRefReturnValue(string $operationType): string
    {
        return $operationType === self::OPERATION_GET || $operationType === self::OPERATION_SET ? '& ' : '';
    }

    /**
     * Retrieves the logic to fetch the object on which access should be attempted
     */
    private static function getTargetObject(?PropertyGenerator $valueHolder = null): string
    {
        if ($valueHolder) {
            return '$this->' . $valueHolder->getName();
        }

        return '$realInstanceReflection->newInstanceWithoutConstructor()';
    }

    /**
     * @throws InvalidArgumentException
     */
    private static function getOperation(string $operationType, string $nameParameter, ?string $valueParameter): string
    {
        switch ($operationType) {
            case self::OPERATION_GET:
                return 'return $targetObject->$' . $nameParameter . ';';

            case self::OPERATION_SET:
                if ($valueParameter === null) {
                    throw new InvalidArgumentException('Parameter $valueParameter not provided');
                }

                return '$targetObject->$' . $nameParameter . ' = $' . $valueParameter . '; return $targetObject->$' . $nameParameter . ';';

            case self::OPERATION_ISSET:
                return 'return isset($targetObject->$' . $nameParameter . ');';

            case self::OPERATION_UNSET:
                return 'unset($targetObject->$' . $nameParameter . ');';
        }

        throw new InvalidArgumentException(sprintf('Invalid operation "%s" provided', $operationType));
    }

    /**
     * Generates code to bind operations to the parent scope
     */
    private static function getScopeReBind(): string
    {
        return '$backtrace = debug_backtrace(true, 2);' . "\n"
            . '$scopeObject = isset($backtrace[1][\'object\'])'
            . ' ? $backtrace[1][\'object\'] : new \ProxyManager\Stub\EmptyClassStub();' . "\n"
            . '$accessor = $accessor->bindTo($scopeObject, get_class($scopeObject));' . "\n";
    }
}