<?php
/**
 * Case-insensitive dictionary, suitable for HTTP headers
 *
 * @package Requests\Utilities
 */

namespace WpOrg\Requests\Utility;

use ArrayAccess;
use ArrayIterator;
use IteratorAggregate;
use ReturnTypeWillChange;
use WpOrg\Requests\Exception;

/**
 * Case-insensitive dictionary, suitable for HTTP headers
 *
 * @package Requests\Utilities
 */
class CaseInsensitiveDictionary implements ArrayAccess, IteratorAggregate {
    /**
     * Actual item data
     *
     * @var array
     */
    protected $data = [];

    /**
     * Creates a case insensitive dictionary.
     *
     * @param array $data Dictionary/map to convert to case-insensitive
     */
    public function __construct(array $data = []) {
        foreach ($data as $offset => $value) {
            $this->offsetSet($offset, $value);
        }
    }

    /**
     * Check if the given item exists
     *
     * @param string $offset Item key
     * @return boolean Does the item exist?
     */
    #[ReturnTypeWillChange]
    public function offsetExists($offset) {
        if (is_string($offset)) {
            $offset = strtolower($offset);
        }

        if ($offset === null) {
            $offset = '';
        }

        return isset($this->data[$offset]);
    }

    /**
     * Get the value for the item
     *
     * @param string $offset Item key
     * @return string|null Item value (null if the item key doesn't exist)
     */
    #[ReturnTypeWillChange]
    public function offsetGet($offset) {
        if (is_string($offset)) {
            $offset = strtolower($offset);
        }

        if ($offset === null) {
            $offset = '';
        }

        if (!isset($this->data[$offset])) {
            return null;
        }

        return $this->data[$offset];
    }

    /**
     * Set the given item
     *
     * @param string $offset Item name
     * @param string $value Item value
     *
     * @throws \WpOrg\Requests\Exception On attempting to use dictionary as list (`invalidset`)
     */
    #[ReturnTypeWillChange]
    public function offsetSet($offset, $value) {
        if ($offset === null) {
            throw new Exception('Object is a dictionary, not a list', 'invalidset');
        }

        if (is_string($offset)) {
            $offset = strtolower($offset);
        }

        $this->data[$offset] = $value;
    }

    /**
     * Unset the given header
     *
     * @param string $offset The key for the item to unset.
     */
    #[ReturnTypeWillChange]
    public function offsetUnset($offset) {
        if (is_string($offset)) {
            $offset = strtolower($offset);
        }

        if ($offset === null) {
            $offset = '';
        }

        unset($this->data[$offset]);
    }

    /**
     * Get an iterator for the data
     *
     * @return \ArrayIterator
     */
    #[ReturnTypeWillChange]
    public function getIterator() {
        return new ArrayIterator($this->data);
    }

    /**
     * Get the headers as an array
     *
     * @return array Header data
     */
    public function getAll() {
        return $this->data;
    }
}