Add the ability to sort by date or title

[cameron-michie]

• Closes Different sorting options #228

Describe your changes

Adds the ability to press 'y' to toggle the sort by date. Also adds the ability to press 't' to switch back to sorting by title, and can sort reverse alphabetically by pressing repeatedly. These options now appear in the fullView after pressing '?'.

Related issue/discussion: #228

[andreynering]

Hi @cameron-michie,

I made a small suggestion.

[andreynering]

Some suggestions:

1. Instead of repeating slices.SortStableFunc 4 times, assigning functions and calling in the end (make it a one-liner).
2. Change if/else into a switch case to reduce block inside block.

Suggested change

	func sortMarkdowns(mds []*markdown, sortByDate bool, ascending sortOrder) {
	if sortByDate {
	if ascending {
	slices.SortStableFunc(mds, func(a, b *markdown) int {
	return compareTime(a.Modtime, b.Modtime)
	})
	} else {
	slices.SortStableFunc(mds, func(a, b *markdown) int {
	return -compareTime(a.Modtime, b.Modtime)
	})
	}
	} else {
	if ascending {
	slices.SortStableFunc(mds, func(a, b *markdown) int {
	return cmp.Compare(a.Note, b.Note)
	})
	} else {
	slices.SortStableFunc(mds, func(a, b *markdown) int {
	return -cmp.Compare(a.Note, b.Note)
	})
	}
	}
	}
	func sortMarkdowns(mds []*markdown, sortByDate bool, order sortOrder) {
	var fn func(a, b *markdown) int
	switch {
	case sortByDate && order == ascending:
	fn = func(a, b *markdown) int { return compareTime(a.Modtime, b.Modtime) }
	case sortByDate && order == descending:
	fn = func(a, b *markdown) int { return -compareTime(a.Modtime, b.Modtime) }
	case !sortByDate && order == ascending:
	fn = func(a, b *markdown) int { return cmp.Compare(a.Note, b.Note) }
	case !sortByDate && order == descending:
	fn = func(a, b *markdown) int { return -cmp.Compare(a.Note, b.Note) }
	}
	slices.SortStableFunc(mds, fn)
	}