package board

import (
	"fmt"
	"sort"
)

type StatusListEmptyError struct{}

func (e StatusListEmptyError) Error() string {
	return "the status list must not be empty"
}

type StatusNotExistError struct {
	ID int
}

func (e StatusNotExistError) Error() string {
	return fmt.Sprintf("status ID '%d' does not exist in the database", e.ID)
}

// Status represents the status of the Kanban board.
type Status struct {
	ID       int
	Name     string
	CardIds  []int
	Position int
}

// UpdateID updates the ID of the Status value.
func (s *Status) UpdateId(id int) {
	s.ID = id
}

// Id returns the ID of the Status value.
func (s *Status) Id() int {
	return s.ID
}

// AddCardID adds a card ID to the status' list of card IDs.
func (s *Status) AddCardID(cardID int) {
	// Create a new list if it does not exist
	// and then return.
	if s.CardIds == nil {
		s.CardIds = []int{cardID}

		return
	}

	// Sort list if not sorted.
	if !sort.IntsAreSorted(s.CardIds) {
		sort.Ints(s.CardIds)
	}

	// Get index of the card's ID if it already exists in the list.
	// Return if it already exists in the list
	ind := sort.SearchInts(s.CardIds, cardID)

	if ind < len(s.CardIds) && cardID == s.CardIds[ind] {
		return
	}

	s.CardIds = append(s.CardIds, cardID)
	sort.Ints(s.CardIds)
}

// RemoveCardID removes a card ID from the status' list of card IDs.
func (s *Status) RemoveCardID(cardID int) {
	if s.CardIds == nil {
		return
	}

	// Sort list if not sorted.
	if !sort.IntsAreSorted(s.CardIds) {
		sort.Ints(s.CardIds)
	}

	// Get index of id.
	// If the card ID is somehow not in the list, then ind
	// will be the index where the id can be inserted.
	ind := sort.SearchInts(s.CardIds, cardID)

	if ind >= len(s.CardIds) || cardID != s.CardIds[ind] {
		return
	}

	if len(s.CardIds) == 1 {
		s.CardIds = nil

		return
	}

	// use append to eliminate the id from the new slice
	s.CardIds = append(s.CardIds[:ind], s.CardIds[ind+1:]...)
}

// ByStatusPosition implements sort.Interface for []Status based on the status' position on the Kanban board.
type ByStatusPosition []Status

func (s ByStatusPosition) Len() int {
	return len(s)
}

func (s ByStatusPosition) Swap(i, j int) {
	s[i], s[j] = s[j], s[i]
}

func (s ByStatusPosition) Less(i, j int) bool {
	return s[i].Position < s[j].Position
}

// defaultStatusList returns the default list of statuses.
func defaultStatusList() []Status {
	return []Status{
		{
			ID:       -1,
			Name:     "To Do",
			Position: 1,
			CardIds:  nil,
		},
		{
			ID:       -1,
			Name:     "Doing",
			Position: 2,
			CardIds:  nil,
		},
		{
			ID:       -1,
			Name:     "Done",
			Position: 3,
			CardIds:  nil,
		},
	}
}