// CodeMirror, copyright (c) by Marijn Haverbeke and others
// Distributed under an MIT license: https://codemirror.net/LICENSE

;(function (mod) {
    if (typeof exports == 'object' && typeof module == 'object')
        // CommonJS
        mod(require('../../lib/codemirror'))
    else if (typeof define == 'function' && define.amd)
        // AMD
        define(['../../lib/codemirror'], mod)
    // Plain browser env
    else mod(CodeMirror)
})(function (CodeMirror) {
    'use strict'

    CodeMirror.defineOption('scrollPastEnd', false, function (cm, val, old) {
        if (old && old != CodeMirror.Init) {
            cm.off('change', onChange)
            cm.off('refresh', updateBottomMargin)
            cm.display.lineSpace.parentNode.style.paddingBottom = ''
            cm.state.scrollPastEndPadding = null
        }
        if (val) {
            cm.on('change', onChange)
            cm.on('refresh', updateBottomMargin)
            updateBottomMargin(cm)
        }
    })

    function onChange(cm, change) {
        if (CodeMirror.changeEnd(change).line == cm.lastLine()) updateBottomMargin(cm)
    }

    function updateBottomMargin(cm) {
        var padding = ''
        if (cm.lineCount() > 1) {
            var totalH = cm.display.scroller.clientHeight - 30,
                lastLineH = cm.getLineHandle(cm.lastLine()).height
            padding = totalH - lastLineH + 'px'
        }
        if (cm.state.scrollPastEndPadding != padding) {
            cm.state.scrollPastEndPadding = padding
            cm.display.lineSpace.parentNode.style.paddingBottom = padding
            cm.off('refresh', updateBottomMargin)
            cm.setSize()
            cm.on('refresh', updateBottomMargin)
        }
    }
})