<?php
// C1K REST API with plain PHP 7.0 or newer: no Composer, no curl extension,
// only json and openssl, which every PHP host has (API-09).
//   C1K_API_KEY=c1k_rest_... C1K_ORG_ID=org_... php docs/examples/api.php
$key = getenv('C1K_API_KEY');
$org = getenv('C1K_ORG_ID');
if (!$key || !$org) {
    fwrite(STDERR, "Set C1K_API_KEY and C1K_ORG_ID\n");
    exit(1);
}
define('C1K_BASE', 'https://c1k.me/api/v1/orgs/' . $org);
define('C1K_KEY', $key);

/** One API call. Returns array(payload, etag); throws with the error code and request ID. */
function c1k($method, $path, $body = null, array $headers = array())
{
    $lines = array('Authorization: Bearer ' . C1K_KEY, 'Accept: application/json');
    if ($body !== null) {
        $lines[] = 'Content-Type: application/json';
    }
    foreach ($headers as $name => $value) {
        $lines[] = $name . ': ' . $value;
    }
    $context = stream_context_create(array('http' => array(
        'method' => $method,
        'header' => implode("\r\n", $lines),
        'content' => $body === null ? '' : json_encode($body),
        'ignore_errors' => true,
        'timeout' => 15,
    )));
    $raw = file_get_contents(C1K_BASE . $path, false, $context);
    $status = 0;
    $etag = null;
    $retry = null;
    foreach (isset($http_response_header) ? $http_response_header : array() as $line) {
        if (preg_match('#^HTTP/\S+ (\d{3})#', $line, $m)) {
            $status = (int) $m[1];
        } elseif (stripos($line, 'ETag:') === 0) {
            $etag = trim(substr($line, 5));
        } elseif (stripos($line, 'Retry-After:') === 0) {
            $retry = trim(substr($line, 12));
        }
    }
    $payload = json_decode((string) $raw, true);
    if ($status < 200 || $status >= 300) {
        $e = isset($payload['error']) ? $payload['error'] : array('code' => 'network', 'message' => 'No answer from C1K.', 'request_id' => '-');
        throw new RuntimeException($status . ' ' . $e['code'] . ': ' . $e['message'] . ($retry !== null ? ' (retry after ' . $retry . 's)' : '') . ' [' . $e['request_id'] . ']');
    }
    return array($payload, $etag);
}

// Create with an idempotency key, so a retry after a lost response cannot duplicate the link.
list($created, $etag) = c1k('POST', '/links', array(
    'destination_url' => 'https://venture.example/launch',
    'title' => 'Launch page',
    'utm' => array('source' => 'newsletter', 'medium' => 'email'),
), array('Idempotency-Key' => 'example-' . bin2hex(random_bytes(8))));
$link = $created['data'];
echo 'created ', $link['short_url'], ' version ', $link['version'], "\n";

// Edit with If-Match carrying the current version from the ETag (API-07).
list($edited) = c1k('PATCH', '/links/' . $link['id'], array('title' => 'Launch page (v2)'), array('If-Match' => $etag));
echo 'edited to version ', $edited['data']['version'], "\n";

// List every page.
$cursor = null;
do {
    list($page) = c1k('GET', '/links?limit=100' . ($cursor !== null ? '&cursor=' . rawurlencode($cursor) : ''));
    foreach ($page['data'] as $item) {
        echo $item['short_url'], ' -> ', $item['destination_url'], "\n";
    }
    $cursor = $page['meta']['next_cursor'];
} while ($cursor !== null);

// Analytics, then one poll of the change feed; keep meta.next_cursor for the next poll.
list($stats) = c1k('GET', '/analytics');
echo 'recorded requests ', $stats['data']['totals']['total'], "\n";
list($feed) = c1k('GET', '/events');
foreach ($feed['data'] as $event) {
    echo $event['id'], ' ', $event['time'], ' ', $event['action'], "\n";
}
echo 'next cursor ', var_export($feed['meta']['next_cursor'], true), "\n";