User:Enterprisey/diff-context.js - Wikipedia

Article Images
Code that you insert on this page could contain malicious content capable of compromising your account. If you import a script from another page with "importScript", "mw.loader.load", "iusc", or "lusc", take note that this causes you to dynamically load a remote script, which could be changed by others. Editors are responsible for all edits and actions they perform, including by scripts. User scripts are not centrally supported and may malfunction or become inoperable due to software changes. A guide to help you find broken scripts is available. If you are unsure whether code you are adding to this page is safe, you can ask at the appropriate village pump.
This code will be executed when previewing this page.
Note: After saving, you have to bypass your browser's cache to see the changes. Google Chrome, Firefox, Microsoft Edge and Safari: Hold down the ⇧ Shift key and click the Reload toolbar button. For details and instructions about other browsers, see Wikipedia:Bypass your cache.
// vim: ts=4 sw=4 et ai
( function () {
    var wikitextCache = {};
    function getWikitext( pageName, revision ) {
        if( wikitextCache[ revision ] ) {
            return $.when( wikitextCache[ revision ] );
        }
        return $.getJSON(
            mw.config.get( 'wgScriptPath' ) + '/api.php',
            {
                format: "json",
                action: "query",
                prop: "revisions",
                rvprop: "content",
                rvslots: "main",
                rvlimit: 1,
                rvstartid: revision,
                titles: pageName,
                formatversion: 2,
            }
        ).then( function ( data ) {
            var revObj = data.query.pages[ Object.keys( data.query.pages )[0] ].revisions[0];
            var wikitext = revObj.slots.main.content;
            wikitextCache[ revision ] = wikitext;
            return wikitext;
        } );
    }

    function lineNumFromLineNumCell( cell ) {
        return parseInt( cell.textContent.replace( /,/g, "" ).match( /Line (\d+):/ )[1] );
    }

    function findLineNumberRowIdx( diffTable, direction, rowIdx ) {
        var rows = Array.prototype.slice.call( diffTable.rows );
        var searchRows;
        if( direction === "next" ) {
            searchRows = rows.slice( rowIdx );
        } else {
            searchRows = rows.slice( 0, rowIdx );
            searchRows.reverse();
        }
        return searchRows.find( function ( row ) {
            return row.cells[0].className === "diff-lineno";
        } );
    }

    // I'm probably gonna keep finding off-by-one errors in this code until the heat death of the universe
    function showMore( revision, pageName, direction, rowWithButton, numRowsToShow, targetRow, diffTable ) {
        var rows = Array.prototype.slice.call( diffTable.rows );
        var buttonRowIdx = rows.indexOf( rowWithButton );
        if( direction === "next" ) {
            targetRow = findLineNumberRowIdx( diffTable, "previous", buttonRowIdx );
        }
        var currLineNum = lineNumFromLineNumCell( targetRow.cells[1] );
        var targetRowIdx = Array.prototype.indexOf.call( diffTable.rows, targetRow );
        var currRowIdx = direction === "next" ? buttonRowIdx - 1 : targetRowIdx + 1;
        if( direction === "next" ) {
            currLineNum += buttonRowIdx - rows.indexOf( targetRow ) - 2;
        }
        return getWikitext( pageName, revision ).then( function ( wikitext ) {
            var lines = wikitext.split( "\n" );
            
            var startLineIdx, endLineIdx;
            switch( direction ) {
                case "next":
                    startLineIdx = currLineNum + 1;
                    endLineIdx = currLineNum + numRowsToShow + 1;

                    var nextLineNumberRow = findLineNumberRowIdx( diffTable, "next", buttonRowIdx );
                    if( nextLineNumberRow ) {
                        var limitLineNum = lineNumFromLineNumCell( nextLineNumberRow.cells[1] ) - 1;
                        endLineIdx = Math.min( endLineIdx, limitLineNum );
                    }
                    break;
                case "previous":
                    startLineIdx = currLineNum - numRowsToShow - 1;
                    endLineIdx = currLineNum - 1;

                    var prevLineNumberRow = findLineNumberRowIdx( diffTable, "previous", buttonRowIdx );
                    if( prevLineNumberRow ) {
                        var prevLineNumberRowIdx = rows.indexOf( prevLineNumberRow );
                        var limitLineNum = lineNumFromLineNumCell( prevLineNumberRow.cells[1] ) + ( buttonRowIdx - prevLineNumberRowIdx ) - 2;
                        startLineIdx = Math.max( startLineIdx, limitLineNum );
                    }
                    break;
            }
            startLineIdx = Math.max( 0, startLineIdx );
            endLineIdx = Math.min( lines.length - 1, endLineIdx );
            if( endLineIdx - startLineIdx === 0 ) {
                return true; // no more work can be done
            }
            var actualNumLines = endLineIdx - startLineIdx;
            var linesToShow = lines.slice( startLineIdx, endLineIdx );
            if( direction === "previous" ) {
                linesToShow.reverse();
            }
            var insertionRow = currRowIdx + +( direction === "next" );
            for( var lineCounter = 0; lineCounter < actualNumLines; lineCounter++ ) {
                var currLine = "<div>" + linesToShow[ lineCounter ].replace( /</g, "&lt;" ) + "</div>";
                var newRow = diffTable.insertRow( insertionRow );
                newRow.insertCell( 0 ).appendChild( document.createTextNode( "." ) );
                var newCell = newRow.insertCell( 1 );
                newCell.className = "diff-context";
                newCell.innerHTML = currLine;
                newRow.insertCell( 2 ).appendChild( document.createTextNode( "." ) );
                var newCell2 = newRow.insertCell( 3 );
                newCell2.className = "diff-context";
                newCell2.innerHTML = currLine;
            }
            if( direction === "previous" ) {
                targetRow.cells[0].textContent = "Line " + ( currLineNum - actualNumLines ) + ":";
                targetRow.cells[1].textContent = "Line " + ( currLineNum - actualNumLines ) + ":";
            }
            mw.hook( "diff-update" ).fire( diffTable );
            if( actualNumLines < numRowsToShow ) {
                return true; // we're done
            }
            return false;
        } );
    }

    function makeDropdown() {
        var sel = document.createElement( "select" );
        function add( num ) {
            var opt = document.createElement( "option" );
            opt.value = num;
            opt.textContent = num;
            sel.appendChild( opt );
        }
        add( 1 );
        add( 10 );
        add( 50 );
        add( 100 );
        //add( "all" );
        return sel;
    }

    function addLinks( diffTable ) {
        if( !diffTable.querySelector ) {

            // Assume it's a jquery object
            diffTable = diffTable.get( 0 );
        }

        if( diffTable.getElementsByClassName( "diff-context-container" ).length > 0 ) {

            // We already ran on this diff
            return;
        }

        function makeRow( index, direction, targetRow ) {
            var newRow = diffTable.insertRow( index );
            newRow.className = "context " + direction;
            var newCell = newRow.insertCell( 0 );
            newCell.setAttribute( "colspan", "4" );
            var container = document.createElement( "div" );
            container.className = "diff-context-container";
            container.appendChild( document.createTextNode( "Show " + direction + " " ) );
            var dropdown = makeDropdown();
            container.appendChild( dropdown );
            container.appendChild( document.createTextNode( " lines: " ) );
            var go = document.createElement( "button" );
            go.textContent = "Go";
            var revision = mw.config.get( "wgDiffNewId" );
            var pageName = mw.config.get( "wgPageName" );

            if( diffTable.parentNode && diffTable.parentNode.dataset.mwRevid ) {
                // User contribs page or normal watchlist or history page
                revision = diffTable.parentNode.dataset.mwRevid;
                if( pageName.indexOf( "Special:Contributions" ) === 0 ) {
                    pageName = diffTable.parentNode.querySelector( "a.mw-contributions-title" ).textContent;
                }
            } else if( diffTable.parentNode && diffTable.parentNode.className === "mw-enhanced-rc-nested" ) {
                // Enhanced ("show all changes") watchlist, when multiple revisions are shown for one page
                revision = diffTable.parentNode.parentNode.dataset.mwRevid;
                pageName = diffTable.parentNode.dataset.targetPage;
            } else if( diffTable.id.substring( diffTable.id.length - 7 ) === "display" && diffTable.previousElementSibling.dataset.mwRevid ) {
                // Enhanced watchlist, only one revision shown for a page
                revision = diffTable.previousElementSibling.dataset.mwRevid;
                pageName = diffTable.previousElementSibling.getElementsByClassName( "mw-changeslist-line-inner" )[0].dataset.targetPage;
            }

            go.addEventListener( "click", function ( evt ) {
                var numRowsToShow = parseInt( dropdown.value );
                showMore( revision, pageName, direction, newRow, numRowsToShow, targetRow, diffTable ).then( function ( done ) {
                    if( done ) {
                        this.disabled = true;
                    }
                }.bind( this ) );
                evt.preventDefault();
            }, true );

            container.appendChild( go );
            newCell.appendChild( container );
        }

        var firstTime = true;
        for( var rowIdx = 0, rowCount = diffTable.rows.length; rowIdx < rowCount; rowIdx++ ) {
            var row = diffTable.rows[rowIdx];
            if( row.cells[0].className !== "diff-lineno" ) continue;
            if( !firstTime ) {
                makeRow( rowIdx, "next", row );
                rowIdx++;
            } else {
                firstTime = false;
            }
            makeRow( rowIdx, "previous", row );
            rowIdx++;
        }
        var lineNumCells = diffTable.querySelectorAll( "td.diff-lineno" );
        if( lineNumCells.length ) {
            var lastLineNumRow = Array.prototype.slice.call( lineNumCells, -1 )[0].parentNode;
            makeRow( -1, "next", lastLineNumRow );
        }
    }

    $( function () {
        var diffTable = document.querySelector( "table.diff" );
        if( mw.config.get( "wgDiffNewId" ) && diffTable && diffTable.rows.length > 2 ) {
            mw.loader.addStyleTag( "tr.context td { text-align: center; }" );
            mw.loader.addStyleTag( "tr.context td div.diff-context-container { display: inline-block; border: thin solid #ddd; padding: 0.1em 0.5em; }" );
            addLinks( diffTable );
        }
        mw.hook( "wikipage.diff" ).add( addLinks );
        mw.hook( "new-diff-table" ).add( addLinks );
    } );
} )();