<?php

namespace App\Http;

use App\Validation\FieldValidationFail;
use App\Validation\Validation;
use App\Validation\ValidationFail;
use App\Validation\Validator;
use ArrayAccess;
use Exception;

/**
 * @implements ArrayAccess<string, mixed>
 * */
class HttpRequest implements ArrayAccess {
    /**
     * @var array<string, mixed>
     */
    private array $data;

    /**
     * @param array<string, mixed> $data
     */
    private function __construct(array $data) {
        $this->data = $data;
    }

    /**
     * Creates a new HttpRequest instance, and ensures that the given request data validates the given schema.
     * This is a simple function that only supports flat schemas (non-composed, the data must only be a k/v array pair.)
     * @param array<string, mixed> $request the request's data
     * @param array<string, ValidationFail> $fails a reference to a failure array, that will contain the reported validation failures.
     * @param array<string, Validator[]> $schema the schema to satisfy. a schema is a simple array with a string key (which is the top-level field name), and a set of validators
     * @return HttpRequest|null the built HttpRequest instance, or null if a field is missing, or if any of the schema validator failed
     */
    public static function from(array $request, array &$fails, array $schema): ?HttpRequest {
        $failure = false;
        foreach ($schema as $fieldName => $fieldValidators) {
            if (!isset($request[$fieldName])) {
                $fails[] = FieldValidationFail::missing($fieldName);
                $failure = true;
                continue;
            }
            $failure |= Validation::validate($request[$fieldName], $fieldName, $fails, ...$fieldValidators);
        }

        if ($failure) {
            return null;
        }
        return new HttpRequest($request);
    }

    public function offsetExists($offset): bool {
        return isset($this->data[$offset]);
    }

    /**
     * @param $offset
     * @return mixed
     */
    public function offsetGet($offset) {
        return $this->data[$offset];
    }

    /**
     * @param $offset
     * @param $value
     * @throws Exception
     */
    public function offsetSet($offset, $value) {
        throw new Exception("requests are immutable objects.");
    }

    /**
     * @param $offset
     * @throws Exception
     */
    public function offsetUnset($offset) {
        throw new Exception("requests are immutable objects.");
    }
}