var Slider = mw.libs.revisionSlider.Slider,
	RevisionList = mw.libs.revisionSlider.RevisionList,
	Revision = mw.libs.revisionSlider.Revision;

function makeNRevisions( n ) {
	var revs = [],
		i;
	for ( i = 0; i < n; i++ ) {
		revs.push( new Revision( { revid: i + 1, user: 'Fooo' } ) );
	}
	return new RevisionList( revs );
}

QUnit.module( 'ext.RevisionSlider.Slider' );

QUnit.test( 'has revisions', function ( assert ) {
	var revs = new RevisionList( [
			new Revision( { revid: 1 } ),
			new Revision( { revid: 2 } )
		] ),
		slider = new Slider( revs );

	assert.strictEqual( slider.getRevisionList(), revs );
} );

QUnit.test( 'Given no revisions, first visible revision index is 0', function ( assert ) {
	var slider = new Slider( makeNRevisions( 0 ) );

	assert.strictEqual( slider.getOldestVisibleRevisionIndex(), 0 );
} );

QUnit.test( 'Given 200 revisions sliding once increases oldestVisibleRevisionIndex by the number of revisions per window', function ( assert ) {
	var slider = new Slider( makeNRevisions( 200 ) );
	slider.setRevisionsPerWindow( 50 );
	slider.slide( 1 );

	assert.strictEqual( slider.getOldestVisibleRevisionIndex(), 50 );
} );

QUnit.test( 'oldestVisibleRevisionIndex cannot be higher than revisions.length - revisionsPerWindow', function ( assert ) {
	var slider = new Slider( makeNRevisions( 75 ) );
	slider.setRevisionsPerWindow( 50 );
	slider.slide( 1 );

	assert.strictEqual( slider.getOldestVisibleRevisionIndex(), 25 );
} );

QUnit.test( 'oldestVisibleRevisionIndex cannot be lower than 0', function ( assert ) {
	var slider = new Slider( makeNRevisions( 50 ) );
	slider.oldestVisibleRevisionIndex = 10;
	slider.setRevisionsPerWindow( 20 );
	slider.slide( -1 );

	assert.strictEqual( slider.getOldestVisibleRevisionIndex(), 0 );
} );