<?php
header('content-type: application/json');
function error() {
    $args = func_get_args();
    $response = ['success' => false];
    $response['message'] = (String) array_shift($args);
    $response['data'] = $args;
    die(json_encode($response, JSON_PRETTY_PRINT));
}

function success() {
    $args = func_get_args();
    $response = ['success' => true];
    $response['message'] = (String) array_shift($args);
    $response['data'] = $args;
    die(json_encode($response, JSON_PRETTY_PRINT));
}

function do_curl($opts) {
    $ch = curl_init();
    foreach ($opts as $opt => $opt_val) {
        curl_setopt($ch, $opt, $opt_val);
    }
    $result = curl_exec($ch);
    curl_close($ch);
    return $result;
}

function parse_bitly($str) {
    if(preg_match('/(bit\.ly\/.*)/iu', $str, $m)) return $m[1];
    return 'bit.ly/'.$str;
}

$bitly_credentials = ['user', 'pass']; // username, password

$bitly_id = parse_bitly($_REQUEST['id']);
$bitly_options = [
    'units' => -1, // alwas get all records from bitly
    'unit' => $_REQUEST['unit'] ? $_REQUEST['unit'] : 'day' // custom unit can be specified
];

$authRequest = [
    CURLOPT_URL => 'https://api-ssl.bitly.com/oauth/access_token',
    CURLOPT_USERPWD => implode(':', $bitly_credentials),
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_SSL_VERIFYPEER => false, // disables SSL verification
    CURLOPT_SSL_VERIFYHOST => false, // disables SSL verification
    CURLOPT_POST => 1,
    CURLOPT_POSTFIELDS => http_build_query([
        'client_id' => $client_id,
        'client_secret' => $client_secret,
        'redirect_uri' => 'https://apps.wortise.com/bitly/callback'
    ])
];

// I specify it manually because of the bitly rate limits
$accessToken = 'xx97c668aae99b9xxxc17cbb5cc97ba0f2e9fc1x'; //do_curl($authRequest); // valid bitly tokens appears to be of 40 chars
if(strlen($accessToken) > 40 || strlen($accessToken) < 40) {
    error('Cannot authenticate to bitly', ['auth_result' => $accessToken]);
}

$authorization = 'Authorization: Bearer '.$accessToken;

$clicksRequest = [
    CURLOPT_URL => 'https://api-ssl.bitly.com/v4/bitlinks/'.$bitly_id.'/clicks?'.http_build_query($bitly_options),
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => array($authorization), // injects bitly auth into header
    CURLOPT_SSL_VERIFYPEER => false, // disables SSL verification
    CURLOPT_SSL_VERIFYHOST => false, // disables SSL verification

];

$result = json_decode(do_curl($clicksRequest)); // valid bitly tokens appears to be of 40 chars
if($result->message) {
    error($result->message, ['id' => $bitly_id]);
}


$clicks = $result->link_clicks;
$start = strtotime($_REQUEST['start']);
$end = strtotime($_REQUEST['end']);

if(isset($start) && isset($end) && $end < $start) {
    error('Invalid end date, it must be higher than the start date');
}

if(isset($start) && isset($end) && $start > $end) {
    error('Invalid start date, it must be lower than the end date');
}

if(isset($start) || isset($end)) {
    foreach($clicks as $k => $click) {
        $click_ts = strtotime($click->date);
        if( ! (( $click_ts >= $start || !isset($start) ) && ( $click_ts <= $end || !isset($end) )) ) {
            unset($clicks[$k]);
        }
    }
}

$clicks = array_values($clicks);
success('clicks retrieved with success', ['clicks' => $clicks, 'options' => $bitly_options, 'id' => $bitly_id, 'request' => $_REQUEST]/*, ['res' => $result]*/);