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

// Because sometimes you need to mark the selected *text*.
//
// Adds an option 'styleSelectedText' which, when enabled, gives
// selected text the CSS class given as option value, or
// "CodeMirror-selectedtext" when the value is not a string.

;(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('styleSelectedText', false, function (cm, val, old) {
        var prev = old && old != CodeMirror.Init
        if (val && !prev) {
            cm.state.markedSelection = []
            cm.state.markedSelectionStyle = typeof val == 'string' ? val : 'CodeMirror-selectedtext'
            reset(cm)
            cm.on('cursorActivity', onCursorActivity)
            cm.on('change', onChange)
        } else if (!val && prev) {
            cm.off('cursorActivity', onCursorActivity)
            cm.off('change', onChange)
            clear(cm)
            cm.state.markedSelection = cm.state.markedSelectionStyle = null
        }
    })

    function onCursorActivity(cm) {
        if (cm.state.markedSelection)
            cm.operation(function () {
                update(cm)
            })
    }

    function onChange(cm) {
        if (cm.state.markedSelection && cm.state.markedSelection.length)
            cm.operation(function () {
                clear(cm)
            })
    }

    var CHUNK_SIZE = 8
    var Pos = CodeMirror.Pos
    var cmp = CodeMirror.cmpPos

    function coverRange(cm, from, to, addAt) {
        if (cmp(from, to) == 0) return
        var array = cm.state.markedSelection
        var cls = cm.state.markedSelectionStyle
        for (var line = from.line; ; ) {
            var start = line == from.line ? from : Pos(line, 0)
            var endLine = line + CHUNK_SIZE,
                atEnd = endLine >= to.line
            var end = atEnd ? to : Pos(endLine, 0)
            var mark = cm.markText(start, end, { className: cls })
            if (addAt == null) array.push(mark)
            else array.splice(addAt++, 0, mark)
            if (atEnd) break
            line = endLine
        }
    }

    function clear(cm) {
        var array = cm.state.markedSelection
        for (var i = 0; i < array.length; ++i) array[i].clear()
        array.length = 0
    }

    function reset(cm) {
        clear(cm)
        var ranges = cm.listSelections()
        for (var i = 0; i < ranges.length; i++) coverRange(cm, ranges[i].from(), ranges[i].to())
    }

    function update(cm) {
        if (!cm.somethingSelected()) return clear(cm)
        if (cm.listSelections().length > 1) return reset(cm)

        var from = cm.getCursor('start'),
            to = cm.getCursor('end')

        var array = cm.state.markedSelection
        if (!array.length) return coverRange(cm, from, to)

        var coverStart = array[0].find(),
            coverEnd = array[array.length - 1].find()
        if (!coverStart || !coverEnd || to.line - from.line <= CHUNK_SIZE || cmp(from, coverEnd.to) >= 0 || cmp(to, coverStart.from) <= 0) return reset(cm)

        while (cmp(from, coverStart.from) > 0) {
            array.shift().clear()
            coverStart = array[0].find()
        }
        if (cmp(from, coverStart.from) < 0) {
            if (coverStart.to.line - from.line < CHUNK_SIZE) {
                array.shift().clear()
                coverRange(cm, from, coverStart.to, 0)
            } else {
                coverRange(cm, from, coverStart.from, 0)
            }
        }

        while (cmp(to, coverEnd.to) < 0) {
            array.pop().clear()
            coverEnd = array[array.length - 1].find()
        }
        if (cmp(to, coverEnd.to) > 0) {
            if (to.line - coverEnd.from.line < CHUNK_SIZE) {
                array.pop().clear()
                coverRange(cm, coverEnd.from, to)
            } else {
                coverRange(cm, coverEnd.to, to)
            }
        }
    }
})