package cache

import (
	"encoding/gob"
	"time"

	"github.com/git-bug/git-bug/entities/common"
	"github.com/git-bug/git-bug/entity"
	"github.com/git-bug/git-bug/util/lamport"
)

// Package initialisation used to register the type for (de)serialization
func init() {
	gob.Register(BugExcerpt{})
}

var _ Excerpt = &BugExcerpt{}

// BugExcerpt hold a subset of the bug values to be able to sort and filter bugs
// efficiently without having to read and compile each raw bugs.
type BugExcerpt struct {
	id entity.Id

	CreateLamportTime lamport.Time
	EditLamportTime   lamport.Time
	CreateUnixTime    int64
	EditUnixTime      int64

	AuthorId     entity.Id
	Status       common.Status
	Labels       []common.Label
	Title        string
	LenComments  int
	Actors       []entity.Id
	Participants []entity.Id

	CreateMetadata map[string]string
}

func NewBugExcerpt(b *BugCache) *BugExcerpt {
	snap := b.Snapshot()
	participantsIds := make([]entity.Id, 0, len(snap.Participants))
	for _, participant := range snap.Participants {
		participantsIds = append(participantsIds, participant.Id())
	}

	actorsIds := make([]entity.Id, 0, len(snap.Actors))
	for _, actor := range snap.Actors {
		actorsIds = append(actorsIds, actor.Id())
	}

	e := &BugExcerpt{
		id:                b.Id(),
		CreateLamportTime: b.CreateLamportTime(),
		EditLamportTime:   b.EditLamportTime(),
		CreateUnixTime:    b.FirstOp().Time().Unix(),
		EditUnixTime:      snap.EditTime().Unix(),
		AuthorId:          snap.Author.Id(),
		Status:            snap.Status,
		Labels:            snap.Labels,
		Actors:            actorsIds,
		Participants:      participantsIds,
		Title:             snap.Title,
		LenComments:       len(snap.Comments),
		CreateMetadata:    b.FirstOp().AllMetadata(),
	}

	return e
}

func (b *BugExcerpt) setId(id entity.Id) {
	b.id = id
}

func (b *BugExcerpt) Id() entity.Id {
	return b.id
}

func (b *BugExcerpt) CreateTime() time.Time {
	return time.Unix(b.CreateUnixTime, 0)
}

func (b *BugExcerpt) EditTime() time.Time {
	return time.Unix(b.EditUnixTime, 0)
}

/*
 * Sorting
 */

type BugsById []*BugExcerpt

func (b BugsById) Len() int {
	return len(b)
}

func (b BugsById) Less(i, j int) bool {
	return b[i].id < b[j].id
}

func (b BugsById) Swap(i, j int) {
	b[i], b[j] = b[j], b[i]
}

type BugsByCreationTime []*BugExcerpt

func (b BugsByCreationTime) Len() int {
	return len(b)
}

func (b BugsByCreationTime) Less(i, j int) bool {
	if b[i].CreateLamportTime < b[j].CreateLamportTime {
		return true
	}

	if b[i].CreateLamportTime > b[j].CreateLamportTime {
		return false
	}

	// When the logical clocks are identical, that means we had a concurrent
	// edition. In this case we rely on the timestamp. While the timestamp might
	// be incorrect due to a badly set clock, the drift in sorting is bounded
	// by the first sorting using the logical clock. That means that if users
	// synchronize their bugs regularly, the timestamp will rarely be used, and
	// should still provide a kinda accurate sorting when needed.
	return b[i].CreateUnixTime < b[j].CreateUnixTime
}

func (b BugsByCreationTime) Swap(i, j int) {
	b[i], b[j] = b[j], b[i]
}

type BugsByEditTime []*BugExcerpt

func (b BugsByEditTime) Len() int {
	return len(b)
}

func (b BugsByEditTime) Less(i, j int) bool {
	if b[i].EditLamportTime < b[j].EditLamportTime {
		return true
	}

	if b[i].EditLamportTime > b[j].EditLamportTime {
		return false
	}

	// When the logical clocks are identical, that means we had a concurrent
	// edition. In this case we rely on the timestamp. While the timestamp might
	// be incorrect due to a badly set clock, the drift in sorting is bounded
	// by the first sorting using the logical clock. That means that if users
	// synchronize their bugs regularly, the timestamp will rarely be used, and
	// should still provide a kinda accurate sorting when needed.
	return b[i].EditUnixTime < b[j].EditUnixTime
}

func (b BugsByEditTime) Swap(i, j int) {
	b[i], b[j] = b[j], b[i]
}