// Based on: https://gist.github.com/stephenquan/fcad6ecd4b28051c61cf48853e39c9e4

// Implements a convenient ListModel that contains sorted items.
// properties:
//   sortKey: specifies one or more key to sort on with an optional "-" prefix to set descending order
//   compareFunc: allows you to replace the default compare function with your own
// methods:
//   insertSorted(obj) - uses binary search insertion sort, duplicates aren't allowed, last in wins.
//   sort() - leverages from Array.prototype.sort() to rapidly sort all items to a new compareFunc
//   load() - load from another model
import QtQuick 2.9

ListModel {
    id: sortedListModel

    property var compareFunc: null

    onCompareFuncChanged: sort()

    function internalCompareFunc(obj1, obj2) {
        return compareFunc(obj1, obj2)
    }

    function sort() {
        listModelSort(sortedListModel, compareFunc)
    }

    function insertSorted(item) {
        listModelInsertSorted(sortedListModel, compareFunc, item)
    }

    function listModelSort(listModel, compareFunc) {
        var indexes = new Array(listModel.count)
        for (var i = 0; i < listModel.count; i++)
            indexes[i] = i
        indexes.sort(function (indexA, indexB) {
            return compareFunc(get(indexA), get(indexB))
        })
        var sorted = 0
        while (sorted < indexes.length && sorted === indexes[sorted])
            sorted++
        if (sorted === indexes.length)
            return
        for (i = sorted; i < indexes.length; i++) {
            var idx = indexes[i]
            listModel.move(idx, listModel.count - 1, 1)
            listModel.insert(idx, {

                             })
        }
        listModel.remove(sorted, indexes.length - sorted)
    }

    function listModelIndexOf(listModel, startIndex, endIndex, item, compareFunc) {
        if (startIndex > endIndex)
            return startIndex
        var startItem = listModel.get(startIndex)
        var startCmp = compareFunc(item, startItem)
        if (startCmp <= 0)
            return startIndex
        if (endIndex <= startIndex)
            return startIndex + 1
        var endItem = listModel.get(endIndex)
        var endCmp = compareFunc(item, endItem)
        if (endCmp === 0)
            return endIndex
        if (endCmp > 0)
            return endIndex + 1
        while (endIndex > startIndex + 1) {
            var midIndex = (startIndex + endIndex) >> 1
            var midItem = listModel.get(midIndex)
            var midCmp = compareFunc(item, midItem)
            if (midCmp === 0)
                return midIndex
            if (midCmp > 0)
                endIndex = midIndex
            else
                startIndex = midIndex
        }
        return endIndex
    }

    function listModelInsertSorted(listModel, compareFunc, item) {
        if (Array.isArray(item)) {
            listModelInsertSortedArray(listModel, compareFunc, item)
            return
        }

        try {
            if (item instanceof ListModel) {
                listModelInsertedSortedListModel(item)
                return
            }
        } catch (err) {

        }

        if (listModel.count === 0) {
            listModel.append(item)
            return
        }
        var index = listModelIndexOf(listModel, 0, listModel.count - 1, item,
                                     compareFunc)
        if (index >= listModel.count) {
            listModel.append(item)
            return
        }
        var cmp = compareFunc(item, listModel.get(index))
        if (cmp === 0) {
            if (options && options.unique) {
                listModel.set(index, item)
                return
            }
        }
        listModel.insert(index, item)
    }

    function listModelInsertSortedArray(listModel, compareFunc, arr) {
        for (var i = 0; i < arr.length; i++)
            listModelInsertSorted(listModel, compareFunc, arr[i])
    }

    function listModelInsertSortedListModel(listModel, compareFunc, model) {
        for (var i = 0; i < model.count; i++)
            listModelInsertSorted(listModel, compareFunc, model.get(i))
    }
}