<?php declare(strict_types=1);

require_once('vendor/autoload.php');
require_once(__DIR__ . '/config.php');

use Telegram\Bot\Api;

function getTelegram(): \Telegram\Bot\Api {
    STATIC $tg;
    return $tg = $tg ?? new \Telegram\Bot\Api(BOT_TOKEN);
}

function splitBill($amount) {
    return floor($amount/2);
}

function identity($x) {
    return $x;
}

function getMessageSender($update) {
    return PARTICIPANT_IDS[$update->get('message')->get('from')->get('id')];
}

function getMessageSenderDisplayName($update) {
    return $update->get('message')->get('from')->get('first_name');
}

function canChatWith($update) {
    return in_array($update->get('message')->get('from')->get('id'), array_keys(PARTICIPANT_IDS));
}

function debug($whatever) {
    echo '<pre>';
    print_r($whatever);
    echo '</pre>';
}

function getInbox($inbox) {
    STATIC $inboxes;

    if (!isset($inboxes[$inbox])) {
        $inboxes[$inbox] = imap_open(
            '{imap.gmail.com:993/debug/imap/ssl/novalidate-cert}' . $inbox,
            EMAIL,
            PASSWORD
        );
    }

    return $inboxes[$inbox];
}

function getRules() {
    STATIC $rules;
    return $rules = $rules ?? require 'rules.php';
}

function getString($identifier, ...$vars) {
    STATIC $strings;
    $strings = $strings ?? require 'strings.php';

    return sprintf($strings[$identifier], ...$vars);
}

function formatDate($date) {
    return $date->format(DATE_FORMAT);
}

function ssort($comparitor) {
    return function($array) use ($comparitor) {
        uasort($array, uncurry($comparitor));
        return $array;
    };
}

function uncurry($f) {
    return function($a, $b) use ($f) {
        return $f($a)($b);
    };
}

const sendToGroupChat = 'sendToGroupChat';
function sendToGroupChat(string $message) {
    return getTelegram()->sendMessage(['chat_id' => CHAT_ID, 'text' => $message]);
}

const generateReminderText = 'generateReminderText';
function generateReminderText($message) {
    return getString('billreminder', REMIND_THRESHOLD, $message['service'], splitBill($message['amount']), formatDate($message['due']));
}

const generateNewBillText = 'generateNewBillText';
function generateNewBillText($message) {
    return getString('newbill', $message['service'], splitBill($message['amount']), formatDate($message['due']));
}

const messageNeedsReminder = 'messageNeedsReminder';
function messageNeedsReminder($message) {
    return $message['due']->diff(new DateTimeImmutable)->d == REMIND_THRESHOLD;
}

const lines = 'lines';
function lines(string $string): array {
    return explode("\n", $string);
}

const glue = 'glue';
function glue(string $delim): callable {
    return function(array $strings) use ($delim): string {
        return implode($delim, $strings);
    };
}

const unlines = 'unlines';
function unlines($lines) {
    return implode("\n", $lines);
}

function field($field) {
    return function($array) use ($field) {
        return $array[$field];
    };
}

const ⬄ = '⬄';
function ⬄($a) {
    return function($b) use ($a) {
        return $a <=> $b;
    };
}


function ∘(...$fs) {
    return function($arg) use ($fs) {
        return array_reduce(array_reverse($fs), function($c, $f) {
            return $f($c);
        }, $arg);
    };
}

function map($callable) {
    return function($list) use ($callable) {
        return array_map($callable, $list);
    };
}

function aaray_column($column) {
    return function($array) use ($column) {
        return array_column($array, $column);
    };
}

function aaray_slice($start) {
    return function($length) use ($start) {
        return function($array) use ($length, $start) {
            return array_slice($array, $start, $length);
        };
    };
}

function filter($callable) {
    return function($list) use ($callable) {
        return array_filter($list, $callable);
    };
}

function f∘(callable $f) {
    return function(callable $g) use ($f) {
        return function($arg) use($g, $f) {
            return $f($g($arg));
        };
    };
}

function ∘f(callable $f) {
    return function(callable $g) use ($f) {
        return function($arg) use($g, $f) {
            return $g($f($arg));
        };
    };
}

function ∪($a, $b) {
    return array_merge($a, $b);
}

function getMessagesFromInbox($inbox, array $rules, $unseenOnly = true) {
    return array_filter(
        array_map(
            function($rule, $service) use ($inbox, $unseenOnly) {
                $emails = imap_search($inbox, ['SEEN ', 'UNSEEN '][$unseenOnly] . $rule['imapQuery'], SE_UID);

                if(!$emails) {
                    return [];
                }

                $messageTransform = $rule['messageTransform'] ?? 'identity';
                $dateTransform = $rule['dateTransform'] ?? 'identity';

                $body = quoted_printable_decode(imap_fetchbody($inbox, $emails[0], '1', FT_UID));
                preg_match($rule['regex'], $messageTransform($body), $matches);

                return [
                    'service' => $service,
                    'id' => substr(md5($body), 0, 6),
                    'uid' => $emails[0],
                    'due' => new DateTimeImmutable($dateTransform($matches['due'])),
                    'amount' => $matches['amount']
                ];
            },
            $rules,
            array_keys($rules)
        ),
        function($e) {
            return !!$e;
        }
    );
}