package database

import (
	"github.com/go-pg/pg/v10"
)

type BookLister interface {
	NewBookList(listID, title, username string, description []string) error
	AddBookToList(listID, bookID string) error
	DeleteBookFromList(listID, bookID string) error
	UpdateBookList(listID, title string, description []string) error
	GetBookList(listID string) (*BookList, error)
	GetListsByUser(username string) ([]BookList, error)
	GetListsByBook(bookID string) ([]BookList, error)
}

type BookList struct {
	ID          int    `pg:"type:serial"`
	ListID      string `pg:"type:varchar(16)"`
	Title       string
	Description []string `pg:"description,array"`
	UserID      int      `pg:"type:integer"`
	User        *User    `pg:"rel:has-one"`
	Books       []Book   `pg:"many2many:book_list_entries"`
}

type BookListEntry struct {
	ID         int       `pg:"type:serial"`
	BookListID int       `pg:"type:integer"`
	BookList   *BookList `pg:"rel:has-one"`
	BookID     string    `pg:"type:varchar(16)"`
	Book       *Book     `pg:"rel:has-one"`
}

func (db *pgDB) NewBookList(listID, title, username string, description []string) error {
	user, err := db.getUser(username)
	if err != nil {
		return err
	}

	_, err = db.sql.Model(&BookList{
		ListID:      listID,
		Title:       title,
		Description: description,
		UserID:      user.ID,
	}).Insert()
	return err
}

func (db *pgDB) AddBookToList(listID, bookID string) error {
	list, err := db.GetBookList(listID)
	if err != nil {
		return err
	}

	_, err = db.sql.Model(&BookListEntry{
		BookListID: list.ID,
		BookID:     bookID,
	}).Insert()
	return err
}

func (db *pgDB) DeleteBookFromList(listID, bookID string) error {
	list, err := db.GetBookList(listID)
	if err != nil {
		return err
	}

	_, err = db.sql.Model(&BookListEntry{}).
		Where("book_list_id = ? AND book_id = ?", list.ID, bookID).
		Delete()
	return err
}

func (db *pgDB) UpdateBookList(listID, title string, description []string) error {
	_, err := db.sql.Model(&BookList{}).
		Set("title = ?, description = ?", title, pg.Array(description)).
		Where("list_id = ?", listID).
		Update()
	return err
}

func (db *pgDB) GetBookList(listID string) (*BookList, error) {
	var bookList BookList
	err := db.sql.Model(&bookList).
		Relation("Books").
		Relation("User").
		Where("list_id = ?", listID).
		Select()
	return &bookList, err
}

func (db *pgDB) GetListsByUser(username string) ([]BookList, error) {
	var bookLists []BookList

	user, err := db.getUser(username)
	if err != nil {
		return bookLists, err
	}

	err = db.sql.Model(&bookLists).
		Relation("Books").
		Relation("User").
		Where("user_id = ?", user.ID).
		Select()
	return bookLists, err
}

func (db *pgDB) GetListsByBook(bookID string) ([]BookList, error) {
	var bookLists []BookList
	var bookListEntries []BookListEntry

	err := db.sql.Model(&bookListEntries).
		Relation("BookList").
		Where("book_id = ?", bookID).
		Select()
	if err != nil || len(bookListEntries) == 0 {
		return bookLists, err
	}

	whereQuery := `list_id IN (`
	listIDs := make([]interface{}, len(bookListEntries))
	for i, entry := range bookListEntries {
		whereQuery += "?"
		if i < len(bookListEntries)-1 {
			whereQuery += ", "
		}
		listIDs[i] = entry.BookList.ListID
	}
	whereQuery += ")"

	err = db.sql.Model(&bookLists).
		Relation("Books").
		Relation("User").
		Where(whereQuery, listIDs...).
		Select()
	return bookLists, err
}