package file

import (
	"net/http"
	"sort"
	"strconv"
	"strings"
)

// handleSortOrder gets and stores for a Listing the 'sort' and 'order',
// and reads 'limit' if given. The latter is 0 if not given. Sets cookies.
func handleSortOrder(w http.ResponseWriter, r *http.Request, scope string) (sort string, order string, limit int, err error) {
	sort = r.URL.Query().Get("sort")
	order = r.URL.Query().Get("order")
	limitQuery := r.URL.Query().Get("limit")

	// If the query 'sort' or 'order' is empty, use defaults or any values
	// previously saved in Cookies.
	switch sort {
	case "":
		sort = "name"
		if sortCookie, sortErr := r.Cookie("sort"); sortErr == nil {
			sort = sortCookie.Value
		}
	case "name", "size", "type":
		http.SetCookie(w, &http.Cookie{
			Name:   "sort",
			Value:  sort,
			Path:   scope,
			Secure: r.TLS != nil,
		})
	}

	switch order {
	case "":
		order = "asc"
		if orderCookie, orderErr := r.Cookie("order"); orderErr == nil {
			order = orderCookie.Value
		}
	case "asc", "desc":
		http.SetCookie(w, &http.Cookie{
			Name:   "order",
			Value:  order,
			Path:   scope,
			Secure: r.TLS != nil,
		})
	}

	if limitQuery != "" {
		limit, err = strconv.Atoi(limitQuery)
		// If the 'limit' query can't be interpreted as a number, return err.
		if err != nil {
			return
		}
	}

	return
}

// Add sorting method to "Listing"
// it will apply what's in ".Sort" and ".Order"
func (l Listing) applySort() {
	// Check '.Order' to know how to sort
	if l.Order == "desc" {
		switch l.Sort {
		case "name":
			sort.Sort(sort.Reverse(byName(l)))
		case "size":
			sort.Sort(sort.Reverse(bySize(l)))
		case "time":
			sort.Sort(sort.Reverse(byTime(l)))
		default:
			// If not one of the above, do nothing
			return
		}
	} else { // If we had more Orderings we could add them here
		switch l.Sort {
		case "name":
			sort.Sort(byName(l))
		case "size":
			sort.Sort(bySize(l))
		case "time":
			sort.Sort(byTime(l))
		default:
			sort.Sort(byName(l))
			return
		}
	}
}

// Implement sorting for Listing
type byName Listing
type bySize Listing
type byTime Listing

// By Name
func (l byName) Len() int {
	return len(l.Items)
}

func (l byName) Swap(i, j int) {
	l.Items[i], l.Items[j] = l.Items[j], l.Items[i]
}

// Treat upper and lower case equally
func (l byName) Less(i, j int) bool {
	if l.Items[i].IsDir() && !l.Items[j].IsDir() {
		return true
	}

	if !l.Items[i].IsDir() && l.Items[j].IsDir() {
		return false
	}

	return strings.ToLower(l.Items[i].Name()) < strings.ToLower(l.Items[j].Name())
}

// By Size
func (l bySize) Len() int {
	return len(l.Items)
}

func (l bySize) Swap(i, j int) {
	l.Items[i], l.Items[j] = l.Items[j], l.Items[i]
}

const directoryOffset = -1 << 31 // = math.MinInt32
func (l bySize) Less(i, j int) bool {
	iSize, jSize := l.Items[i].Size(), l.Items[j].Size()
	if l.Items[i].IsDir() {
		iSize = directoryOffset + iSize
	}
	if l.Items[j].IsDir() {
		jSize = directoryOffset + jSize
	}
	return iSize < jSize
}

// By Time
func (l byTime) Len() int {
	return len(l.Items)
}
func (l byTime) Swap(i, j int) {
	l.Items[i], l.Items[j] = l.Items[j], l.Items[i]
}
func (l byTime) Less(i, j int) bool {
	return l.Items[i].ModTime().Before(l.Items[j].ModTime())
}