<?php

namespace Kirby\Toolkit;

use Kirby\Exception\BadMethodCallException;
use Kirby\Exception\InvalidArgumentException;

/**
 * The Query class can be used to
 * query arrays and objects, including their
 * methods with a very simple string-based syntax.
 *
 * @package   Kirby Toolkit
 * @author    Bastian Allgeier <bastian@getkirby.com>
 * @link      https://getkirby.com
 * @copyright Bastian Allgeier GmbH
 * @license   https://opensource.org/licenses/MIT
 */
class Query
{
    const PARTS      = '!\.|(\(([^()]+|(?1))*+\))(*SKIP)(*FAIL)!'; // split by dot, but not inside (nested) parens
    const PARAMETERS = '!,|' . self::SKIP . '!'; // split by comma, but not inside skip groups

    const NO_PNTH = '\([^(]+\)(*SKIP)(*FAIL)';
    const NO_SQBR = '\[[^]]+\](*SKIP)(*FAIL)';
    const NO_DLQU = '\"(?:[^"\\\\]|\\\\.)*\"(*SKIP)(*FAIL)';  // allow \" escaping inside string
    const NO_SLQU = '\'(?:[^\'\\\\]|\\\\.)*\'(*SKIP)(*FAIL)'; // allow \' escaping inside string
    const SKIP    = self::NO_PNTH . '|' . self::NO_SQBR . '|' .
                    self::NO_DLQU . '|' . self::NO_SLQU;

    /**
     * The query string
     *
     * @var string
     */
    protected $query;

    /**
     * Queryable data
     *
     * @var array
     */
    protected $data;

    /**
     * Creates a new Query object
     *
     * @param string|null $query
     * @param array|object $data
     */
    public function __construct(?string $query = null, $data = [])
    {
        $this->query = $query;
        $this->data  = $data;
    }

    /**
     * Returns the query result if anything
     * can be found, otherwise returns null
     *
     * @return mixed
     */
    public function result()
    {
        if (empty($this->query) === true) {
            return $this->data;
        }

        return $this->resolve($this->query);
    }

    /**
     * Resolves the query if anything
     * can be found, otherwise returns null
     *
     * @param string $query
     * @return mixed
     *
     * @throws \Kirby\Exception\BadMethodCallException If an invalid method is accessed by the query
     */
    protected function resolve(string $query)
    {
        // direct key access in arrays
        if (is_array($this->data) === true && array_key_exists($query, $this->data) === true) {
            return $this->data[$query];
        }

        $parts = $this->parts($query);
        $data  = $this->data;
        $value = null;

        foreach ($parts as $part) {
            $info   = $this->part($part);
            $method = $info['method'];
            $args   = $info['args'];

            if (is_array($data)) {
                if (array_key_exists($method, $data) === true) {
                    $value = $data[$method];

                    if (is_a($value, 'Closure') === true) {
                        $value = $value(...$args);
                    } elseif ($args !== []) {
                        throw new InvalidArgumentException('Cannot access array element ' . $method . ' with arguments');
                    }
                } else {
                    static::accessError($data, $method, 'property');
                }
            } elseif (is_object($data)) {
                if (
                    method_exists($data, $method) === true ||
                    method_exists($data, '__call') === true
                ) {
                    $value = $data->$method(...$args);
                } elseif (
                    $args === [] && (
                        property_exists($data, $method) === true ||
                        method_exists($data, '__get') === true
                    )
                ) {
                    $value = $data->$method;
                } else {
                    $label = ($args === []) ? 'method/property' : 'method';
                    static::accessError($data, $method, $label);
                }
            } else {
                // further parts on a scalar/null value
                static::accessError($data, $method, 'method/property');
            }

            // continue with the current value for the next part
            $data = $value;
        }

        return $value;
    }

    /**
     * Breaks the query string down into its components
     *
     * @param string $query
     * @return array
     */
    protected function parts(string $query): array
    {
        return preg_split(self::PARTS, trim($query), -1, PREG_SPLIT_NO_EMPTY);
    }

    /**
     * Analyzes each part of the query string and
     * extracts methods and method arguments
     *
     * @param string $part
     * @return array
     */
    protected function part(string $part): array
    {
        if (Str::endsWith($part, ')') === true) {
            $method = Str::before($part, '(');

            // the args are everything inside the *outer* parentheses
            $args = Str::substr($part, Str::position($part, '(') + 1, -1);
            $args = preg_split(self::PARAMETERS, $args);
            $args = array_map('self::parameter', $args);

            return compact('method', 'args');
        } else {
            return [
                'method' => $part,
                'args'   => []
            ];
        }
    }

    /**
     * Converts a parameter of a query to
     * its proper native PHP type
     *
     * @param string $arg
     * @return mixed
     */
    protected function parameter(string $arg)
    {
        $arg = trim($arg);

        // string with double quotes
        if (substr($arg, 0, 1) === '"' && substr($arg, -1) === '"') {
            return str_replace('\"', '"', substr($arg, 1, -1));
        }

        // string with single quotes
        if (substr($arg, 0, 1) === "'" && substr($arg, -1) === "'") {
            return str_replace("\'", "'", substr($arg, 1, -1));
        }

        // boolean or null
        switch ($arg) {
            case 'null':
                return null;
            case 'false':
                return false;
            case 'true':
                return true;
        }

        // numeric
        if (is_numeric($arg) === true) {
            return (float)$arg;
        }

        // array: split and recursive sanitizing
        if (substr($arg, 0, 1) === '[' && substr($arg, -1) === ']') {
            $arg = substr($arg, 1, -1);
            $arg = preg_split(self::PARAMETERS, $arg);
            return array_map('self::parameter', $arg);
        }

        // resolve parameter for objects and methods itself
        return $this->resolve($arg);
    }

    /**
     * Throws an exception for an access to an invalid method
     *
     * @param mixed $data Variable on which the access was tried
     * @param string $name Name of the method/property that was accessed
     * @param string $label Type of the name (`method`, `property` or `method/property`)
     * @return void
     *
     * @throws \Kirby\Exception\BadMethodCallException
     */
    protected static function accessError($data, string $name, string $label): void
    {
        $type = strtolower(gettype($data));
        if ($type === 'double') {
            $type = 'float';
        }

        $nonExisting = in_array($type, ['array', 'object']) ? 'non-existing ' : '';

        $error = 'Access to ' . $nonExisting . $label . ' ' . $name . ' on ' . $type;
        throw new BadMethodCallException($error);
    }
}
