package database

import (
	"time"

	log "github.com/cihub/seelog"
)

type Visit struct {
	ID        int    `pg:"type:serial"`
	Downloads int    `pg:"type:integer,notnull"`
	Views     int    `pg:"type:integer,notnull"`
	BookID    string `pg:"type:varchar(16),unique"`
	Book      *Book  `pg:"rel:has-one"`
}

func (db *pgDB) IncViews(ID string) error {
	visit := &Visit{
		Downloads: 0,
		Views:     1,
		BookID:    ID,
	}
	_, err := db.sql.Model(visit).
		OnConflict("(book_id) DO UPDATE").
		Set("views = Visit.views + 1").
		Insert()
	return err
}

func (db *pgDB) IncDownloads(ID string) error {
	visit := &Visit{
		Downloads: 1,
		Views:     0,
		BookID:    ID,
	}
	_, err := db.sql.Model(visit).
		OnConflict("(book_id) DO UPDATE").
		Set("downloads = Visit.downloads + 1").
		Insert()
	return err
}

func (db *pgDB) GetDownloadCounter(ID string) (int, error) {
	var num int
	err := db.sql.Model(&Visit{}).
		Column("downloads").
		Where("book_id = ?", ID).
		Select(&num)
	return num, err
}

func (db *pgDB) GetFrontPage() FrontPage {
	return db.frontPage
}

func (db *pgDB) frontPageUpdater() {
	periodicity := 5 * time.Minute

	for true {
		tags, err := db.getTags(tagsDisplay)
		if err != nil {
			log.Error("Error updating tags: ", err)
		} else {
			db.frontPage.Tags = tags
		}

		count, err := db.getCount()
		if err != nil {
			log.Error("Error updating count: ", err)
		} else {
			db.frontPage.Count = count
		}

		last, _, err := db.GetBooks("", booksFrontPage, 0)
		if err != nil {
			log.Error("Error updating last books: ", err)
		} else {
			db.frontPage.Last = last
		}

		visited, err := db.getVisitedBooks(booksFrontPage)
		if err != nil {
			log.Error("Error updating visited books: ", err)
		} else {
			db.frontPage.Visited = visited
		}

		download, err := db.getDownloadedBooks(booksFrontPage)
		if err != nil {
			log.Error("Error updating download books: ", err)
		} else {
			db.frontPage.Download = download
		}

		time.Sleep(periodicity)
	}
}

func (db *pgDB) GetTags() ([]string, error) {
	return db.frontPage.Tags, nil
}

func (db *pgDB) getVisitedBooks(num int) (books []Book, err error) {
	err = db.sql.Model(&books).
		Column("book.*").
		Join("INNER JOIN visits ON book.id = visits.book_id ").
		Where("visits.views > 0 AND book.active").
		Order("views DESC NULLS LAST").
		Limit(num).
		Select()
	return
}

func (db *pgDB) getDownloadedBooks(num int) (books []Book, err error) {
	err = db.sql.Model(&books).
		Column("book.*").
		Join("INNER JOIN visits ON book.id = visits.book_id ").
		Where("visits.downloads > 0 AND book.active").
		Order("downloads DESC NULLS LAST").
		Limit(num).
		Select()
	return
}

func (db *pgDB) getTags(num int) (tags []string, err error) {
	err = db.sql.Model(&Book{}).
		ColumnExpr("unnest(tags) as tag").
		Where("active = true").
		Group("tag").
		OrderExpr("count(*) DESC").
		Limit(num).
		Select(&tags)
	return tags, err
}

func (db *pgDB) getCount() (count int, err error) {
	err = db.sql.Model(&Book{}).
		ColumnExpr("count(*)").
		Where("active = true").
		Select(&count)
	return count, err
}