<?php
include_once '_include.php';

/**
 * Works for gettings comments
 * And load more comments
 * Algo is quite hard to understand
 * And, it's not the best way to select all records from the database
 */

use Util\Ajax; // responsible for returning JSON response
use Util\Input;

$user = new Groups\User($mysqli);
$userId = $user -> getId();

$postId = Input::int( $_GET['postId'] ?? 0 );
// some validations are dropped out, as not related to the question

$helper = $mysqli -> getHelper(); // helper is https://github.com/ThingEngineer/PHP-MySQLi-Database-Class#table-of-contents

// for later use
$time = time();

$targetTime = Input::int($_GET['targetTime'] ?? 0);
// when a user loads a page, he will get comments in a sorting
// but, the sort changes when a comment gets upvotes (or downvotes)
// therefore, target time is used to count upvotes until the time the user first loaded the page
// this is sent to the client-side, and sent back in the next request
if (!$targetTime)
    $targetTime = $time;

// cvu = comments votes user
$commentsResults = $helper -> rawQuery( '
    SELECT
        Id, UserId, PostId, CreateTime, Content, ParentId,
        IsOfficial, IF ( IsRemovedByMod = 1 OR IsRemovedByUser = 1, 1, 0 ) as IsDeleted,
        UserVote AS UserVoteStatus,
    upvotes - downvotes as Score
    FROM (
        SELECT c.*,
        COALESCE(SUM( IF(v.Value = 1, 1, 0) ), 0) as upvotes,
        COALESCE(SUM( IF(v.Value = -1, 1, 0) ), 0) as downvotes,
        ( SELECT Value from postscommentsvotes cvu WHERE cvu.CommentId = c.Id AND UserId = ? LIMIT 1 ) as  UserVote
        FROM postscomments c
        LEFT JOIN postscommentsvotes v ON v.CommentId = c.Id AND v.Time <= ?
        WHERE c.PostId = ? AND
        (
            ( c.IsRemovedByUser = 0 AND c.IsRemovedByMod = 0 )
                OR
            ( ( SELECT 1 FROM postscomments c2 WHERE c2.ParentId = c.Id LIMIT 1  ) = 1 )
        )
        GROUP BY c.Id
    ) as s
    ORDER BY COALESCE( ((upvotes + 1.9208) / (upvotes + downvotes) -
    1.96 * SQRT((upvotes * downvotes) / (upvotes + downvotes) + 0.9604) /
    (upvotes + downvotes)) / (1 + 3.8416 / (upvotes + downvotes)) , 0) DESC
',
array ( $userId, $targetTime, $postId )
);

if ($helper -> count === 0)
    Ajax::success( ['comments' => []] ); // no comments

// this is the hard work done using PHP
// comments are sorted and grouped

// variables
$comments = [];
$groupedComments = [
    'parent' => []
];
$maxParentComments = 20;
$maxChildCommentsPerParent = 5;
$userIdx = []; // note that usernames are not in this application. So, user ids are needed to fetch them
$hasMores = []; // comments which has more childs

// load more options
$offset = Input::int( $_GET['offset'] ?? 0 );
// use POST_PARENT as string to load more parent comments
$targetedParent = isset( $_GET['targetedParentId'] ) ? Input::int($_GET['targetedParentId']) : null;
// save skips (for load more)
$skipped = [];
// parents found in targeted search
$parentsFoundInTargetedSearch = [];

function addToHasMore($commentId) {
    global $hasMores;
    if (! in_array($commentId, $hasMores) ) {
        $hasMores[] = $commentId;
    }
}
function getSkipped($key) {
    global $skipped;
    return $skipped[$key] ?? 0;
}
function increaseSkipped($key) {
    global $skipped;
    if (!isset($skipped[$key]))
        $skipped[$key] = 0;
    $skipped[$key]++;
}

function addComment($key, $comment) {
    global $groupedComments, $userIdx;
    $groupedComments[$key][] = $comment;
    $userIdx[] = $comment['UserId'];
}

foreach ($commentsResults as $comment) {
    $commentId = $comment['Id'];
    $comments[$commentId] = $comment;
}
// for memory saving
unset($commentsResults);


if ($targetedParent !== null && $targetedParent !== 'POST_PARENT') {
    // we need a list of parent ids of targeted
    // this is done for a ordered comments
    // because comment ordering will have children before parents
    $orderedComments = $comments;
    uasort($orderedComments, function($a, $b) {
        return $a['Id'] - $b['Id'];
    });
    foreach ($orderedComments as $c) {
        if ($c['ParentId'] === $targetedParent || in_array($c['ParentId'], $parentsFoundInTargetedSearch))
            $parentsFoundInTargetedSearch[] = $c['Id'];
    }
    unset($orderedComments);
}

foreach ($comments as $commentId => $commentArray) {
    $parentId = $commentArray['ParentId'];
    if ($parentId === null) { // main comments

        if ($targetedParent !== 'POST_PARENT' && $targetedParent !== null)
            // not interested in parent comments ;)
            continue;

        if ( count($groupedComments['parent']) < $maxParentComments ) {
            if ( $offset && getSkipped('parent') < $offset ) {
                increaseSkipped('parent');
                continue;
            }
            addComment('parent', $commentArray);
        } else {
            addToHasMore($parentId);
        }
    } else {
        // parent group is already set
        if ( !isset( $groupedComments[$parentId] ) ) {
            $groupedComments[$parentId] = [];
        }

        $parentFoundInTargetedSearch = in_array($parentId, $parentsFoundInTargetedSearch);
        if (
            $targetedParent !== null &&  // not targeting
            $targetedParent !== $parentId && // not the targeting parent
            !$parentFoundInTargetedSearch // if this parent was
        ) {
            continue;
        }

        if ( count($groupedComments[$parentId]) < $maxChildCommentsPerParent ) {
            if ( $offset && getSkipped($parentId) < $offset && !$parentFoundInTargetedSearch ) {
                increaseSkipped($parentId);
                continue;
            }
            addComment($parentId, $commentArray);

        } else {
            addToHasMore($parentId);
        }
    }
}
// remove empties
$groupedComments = array_filter( $groupedComments );

// get user data
$userData = HyvorAuth\Userbase::getById($userIdx);

// return JSON response
Ajax::success(
    [
        'comments' => $groupedComments,
        'meta' => [
            'hasMores' => $hasMores,
            'targetTime' => $targetTime
        ],
        'userData' => $userData
    ]
);