package db

// Database is laid out like this:
// mapper/<mapper_id>/trackers/<channel_id> -> priority
// mapper/<mapper_id>/latestEvent
// channel/<channel_id>/tracks/<mapper_id> -> priority

import (
	"strconv"

	"github.com/pkg/errors"
	"gorm.io/driver/sqlite"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"

	"subscribe-bot/osuapi"
)

var (
	LATEST_EVENT = []byte("latestEvent")
	MAPPERS      = []byte("mapper")
	CHANNELS     = []byte("channels")
)

type Db struct {
	gorm *gorm.DB
	api  *osuapi.Osuapi
}

func OpenDb(path string, api *osuapi.Osuapi) (db *Db, err error) {
	gorm, err := gorm.Open(sqlite.Open(path), &gorm.Config{})
	if err != nil {
		panic("failed to connect database")
	}

	// auto-migrate
	gorm.AutoMigrate(&Config{})
	gorm.AutoMigrate(&User{})
	gorm.AutoMigrate(&Beatmapset{})
	gorm.AutoMigrate(&DiscordChannel{})

	db = &Db{gorm, api}
	return
}

// Loop over channels that are tracking this specific mapper
func (db *Db) IterTrackingChannels(mapperId int, fn func(channel DiscordChannel) error) (err error) {
	var channels []DiscordChannel
	db.gorm.Model(&User{ID: mapperId}).Association("TrackingChannels").Find(&channels)
	for _, channel := range channels {
		fn(channel)
	}

	return
}

// Loop over tracked mappers for this channel
func (db *Db) IterChannelTrackedMappers(channelId string, fn func(user User) error) (err error) {
	var mappers []User
	db.gorm.Model(&DiscordChannel{ID: channelId}).Association("TrackedMappers").Find(&mappers)
	for _, mapper := range mappers {
		fn(mapper)
	}

	return
}

// Loop over all tracked mappers
func (db *Db) IterAllTrackedMappers(fn func(user User) error) (err error) {
	var mappers []User
	db.gorm.Find(&mappers)
	for _, mapper := range mappers {
		fn(mapper)
	}

	return
}

func (db *Db) UpdateMapperLastEvent(userId int, eventId int) (err error) {
	if eventId == -1 {
		var events []osuapi.Event
		events, err = db.api.GetUserEvents(userId, 1, 0)
		if err != nil {
			err = errors.Wrap(err, "couldn't get user events from API")
			return
		}

		if len(events) > 0 {
			eventId = events[0].ID
		}
	}

	db.gorm.Model(&User{}).Where("id = ?", userId).Update("latest_event_id", eventId)
	return nil
}

// Get the latest event ID of this mapper, if they have one
func (db *Db) MapperLastEvent(userId int) (has bool, id int) {
	var user User
	db.gorm.Select("latest_event_id").First(&user)
	return true, user.LatestEventID
}

// Start tracking a new mapper (if they're not already tracked)
func (db *Db) ChannelTrackMapper(channelId string, mapperId int, priority int) (err error) {
	err = db.gorm.Model(&DiscordChannel{ID: channelId}).Association("TrackedMappers").Append(db.getUser(mapperId))
	if err != nil {
		err = errors.Wrap(err, "could not add tracking for channel "+channelId)
		return
	}

	err = db.UpdateMapperLastEvent(mapperId, -1)
	if err != nil {
		err = errors.Wrap(err, "could not update mapper latest event")
		return
	}

	return nil
}

func (db *Db) Close() {
}

func (db *Db) getUser(userId int) (user *User, err error) {
	// TODO: cache user info for some time?

	apiUser, err := db.api.GetUser(strconv.Itoa(userId))
	if err != nil {
		err = errors.Wrap(err, "could not retrieve user from the API")
		return
	}

	user = &User{
		ID:       userId,
		Username: apiUser.Username,
		Country:  apiUser.CountryCode,
	}
	db.gorm.Clauses(clause.OnConflict{UpdateAll: true}).Create(user)

	return
}