wikimedia/mediawiki-core

/*!
 * Pre-emptive page parsing edits.
 *
 * See also PageEditStash in PHP.
 */
$( function () {
    var PRIORITY_LOW = 1;
    var PRIORITY_HIGH = 2;

    // Do not attempt to stash "new section" edits, because for those cases the ParserOutput
    // varies on the edit summary field, and thus pre-parsing the page whilst that field is
    // being typed in would be counter-productive. (The field is re-purposed for the new
    // section's heading.)
    var $form = $( '#editform' );
    var section = $form.find( '[name=wpSection]' ).val();
    if ( !$form.length || section === 'new' ) {
        return;
    }

    var lastText, lastSummary, lastTextHash;
    var lastPriority = 0;
    var $text = $form.find( '#wpTextbox1' );
    var $summary = $form.find( '#wpSummary' );
    var model = $form.find( '[name=model]' ).val();
    var format = $form.find( '[name=format]' ).val();
    var revId = $form.find( '[name=parentRevId]' ).val();

    // Whether the body text content changed since the last stashEdit()
    function isTextChanged() {
        return lastText !== $text.textSelection( 'getContents' );
    }

    // Whether the edit summary has changed since the last stashEdit()
    function isSummaryChanged() {
        return lastSummary !== $summary.textSelection( 'getContents' );
    }

    // Send a request to stash the edit to the API.
    // If a request is in progress, abort it since its payload is stale and the API
    // may limit concurrent stash parses.
    var api = new mw.Api();
    var stashReq;
    function stashEdit() {
        var textChanged = isTextChanged();
        var priority = textChanged ? PRIORITY_HIGH : PRIORITY_LOW;

        if ( stashReq ) {
            if ( lastPriority > priority ) {
                // Stash request for summary change should wait on pending text change stash
                stashReq.then( checkStash );
                return;
            }
            stashReq.abort();
        }

        // Update the "last" tracking variables
        lastSummary = $summary.textSelection( 'getContents' );
        lastPriority = priority;
        if ( textChanged ) {
            lastText = $text.textSelection( 'getContents' );
            // Reset hash
            lastTextHash = null;
        }

        var params = {
            formatversion: 2,
            action: 'stashedit',
            title: mw.config.get( 'wgPageName' ),
            section: section,
            sectiontitle: '',
            summary: lastSummary,
            contentmodel: model,
            contentformat: format,
            baserevid: revId
        };
        if ( lastTextHash ) {
            params.stashedtexthash = lastTextHash;
        } else {
            params.text = lastText;
        }

        var req = api.postWithToken( 'csrf', params );
        stashReq = req;
        req.then( function ( data ) {
            if ( req === stashReq ) {
                stashReq = null;
            }
            if ( data.stashedit && data.stashedit.texthash ) {
                lastTextHash = data.stashedit.texthash;
            } else {
                // Request failed or text hash expired;
                // include the text in a future stash request.
                lastTextHash = null;
            }
        } );
    }

    // Check whether text or summary have changed and call stashEdit()
    function checkStash() {
        if ( !isTextChanged() && !isSummaryChanged() ) {
            return;
        }

        stashEdit();
    }

    var idleTimeout = 3000;
    var timer;
    function onKeyUp( e ) {
        // Ignore keystrokes that don't modify text, like cursor movements.
        // See <http://www.javascripter.net/faq/keycodes.htm> and
        // <http://www.quirksmode.org/js/keys.html>. We don't have to be exhaustive,
        // because the cost of misfiring is low.
        // * Key code 33-40: Page Up/Down, End, Home, arrow keys.
        // * Key code 16-18: Shift, Ctrl, Alt.
        if ( ( e.which >= 33 && e.which <= 40 ) || ( e.which >= 16 && e.which <= 18 ) ) {
            return;
        }

        clearTimeout( timer );
        timer = setTimeout( checkStash, idleTimeout );
    }

    function onSummaryFocus() {
        // Summary typing is usually near the end of the workflow and involves less pausing.
        // Re-stash more frequently in hopes of capturing the final summary before submission.
        idleTimeout = 1000;
        // Stash now since the text is likely the final version. The re-stashes based on the
        // summary are targeted at caching edit checks that need the final summary.
        checkStash();
    }

    function onTextFocus() {
        // User returned to the text field... reset stash rate to default
        idleTimeout = 3000;
    }

    $text.on( {
        keyup: onKeyUp,
        focus: onTextFocus,
        change: checkStash
    } );
    $summary.on( {
        keyup: onKeyUp,
        focus: onSummaryFocus,
        focusout: checkStash
    } );

    if (
        // Reverts may involve use (undo) links; stash as they review the diff.
        // Since the form has a pre-filled summary, stash the edit immediately.
        mw.util.getParamValue( 'undo' ) !== null ||
        // Pressing "show changes" and "preview" also signify that the user will
        // probably save the page soon
        [ 'preview', 'diff' ].indexOf( $form.find( '#mw-edit-mode' ).val() ) > -1
    ) {
        checkStash();
    }
} );