package handlers

import (
	"strconv"
	"time"
)

const (
	// archiveExpiryNever is the archive expiry that keeps archived
	// events forever. It is stored as an ArchiveExpiry of 0, and an
	// empty expiry on a form means the same.
	archiveExpiryNever = "never"

	// tmplKeyArchiveExpiryChoices is the template data key for the
	// entries of a page's archive expiry select.
	tmplKeyArchiveExpiryChoices = "ArchiveExpiryChoices"
)

// archiveChoice is one entry of a database target's archive expiry
// or archive rotation select: the value stored, the label shown, and
// whether the select starts on it.
type archiveChoice struct {
	Value    string
	Label    string
	Selected bool
}

// archiveExpiryChoices lists the archive expiries offered by the new
// webhook page, the add target form and the target edit form.
func archiveExpiryChoices() []archiveChoice {
	return []archiveChoice{
		{Value: archiveExpiryNever, Label: archiveExpiryNever},
		{Value: "1h", Label: "1h"},
		{Value: "12h", Label: "12h"},
		{Value: "24h", Label: "24h"},
		{Value: "720h", Label: "30d"},
		{Value: "2160h", Label: "90d"},
		{Value: "8760h", Label: "365d"},
	}
}

// archiveExpiryOptions returns the choices with expiry selected; an
// empty expiry selects never. An expiry that is not one of the
// choices comes first as its own selected entry, so saving the form
// unchanged keeps it.
func archiveExpiryOptions(expiry string) []archiveChoice {
	if expiry == "" {
		expiry = archiveExpiryNever
	}

	options := archiveExpiryChoices()

	for i := range options {
		if options[i].Value == expiry {
			options[i].Selected = true

			return options
		}
	}

	own := archiveChoice{Value: expiry, Label: expiry, Selected: true}

	return append([]archiveChoice{own}, options...)
}

// formatArchiveExpiry writes a stored ArchiveExpiry the way the
// expiry select spells its values, so the target edit form starts on
// the stored choice: never for 0, a whole number of hours as "720h",
// and anything else as Go writes a duration, which the form accepts
// back unchanged.
func formatArchiveExpiry(expiry time.Duration) string {
	switch {
	case expiry == 0:
		return archiveExpiryNever
	case expiry%time.Hour == 0:
		return strconv.FormatInt(int64(expiry/time.Hour), 10) + "h"
	default:
		return expiry.String()
	}
}