package bouquins

import (
	"database/sql"
)

const (
	STMT_PAGE   = " LIMIT ? OFFSET ?"
	STMT_BOOKS0 = `SELECT books.id AS id,title,series_index,name as series_name,series.id AS series_id 
    FROM books LEFT OUTER JOIN books_series_link ON books.id = books_series_link.book 
    LEFT OUTER JOIN series ON series.id = books_series_link.series `
	STMT_BOOKS_TAGS0 = `SELECT name, books_tags_link.book as book FROM tags, books_tags_link 
    WHERE tags.id = books_tags_link.tag AND books_tags_link.book IN ( SELECT id FROM books `
	STMT_BOOKS_AUTHORS0 = `SELECT authors.id, authors.name, books_authors_link.book as book 
    FROM authors, books_authors_link WHERE books_authors_link.author = authors.id 
    AND books_authors_link.book IN ( SELECT id FROM books `
	STMT_WHERE        = " WHERE "
	STMT_SEARCH_TERM  = " books.sort like ? "
	STMT_BOOL_AND     = " AND "
	STMT_BOOL_OR      = " OR "
	STMT_SEARCH_ORDER = " ORDER BY books.sort"

	STMT_BOOKS_COUNT = "SELECT count(id) FROM books"
	STMT_BOOK        = `SELECT books.id AS id,title, series_index, series.name AS series_name, series.id AS series_id, 
    strftime('%s', timestamp), strftime('%Y', pubdate), isbn,lccn,path,uuid,has_cover, 
    languages.lang_code, publishers.name AS pubname FROM books 
    LEFT OUTER JOIN books_languages_link ON books_languages_link.book = books.id 
    LEFT OUTER JOIN languages ON languages.id = books_languages_link.lang_code 
    LEFT OUTER JOIN data ON data.book = books.id 
    LEFT OUTER JOIN books_series_link ON books.id = books_series_link.book 
    LEFT OUTER JOIN series ON series.id = books_series_link.series 
    LEFT OUTER JOIN books_publishers_link ON books.id = books_publishers_link.book 
    LEFT OUTER JOIN publishers ON publishers.id = books_publishers_link.publisher 
    WHERE books.id = ?`
	STMT_BOOK_TAGS    = "SELECT name FROM tags, books_tags_link WHERE tags.id = books_tags_link.tag AND books_tags_link.book = ?"
	STMT_BOOK_AUTHORS = `SELECT authors.id, authors.name, books_authors_link.book as book 
    FROM authors, books_authors_link WHERE books_authors_link.author = authors.id 
    AND books_authors_link.book = ?`
	STMT_BOOK_DATA                = "SELECT data.name, data.format, data.uncompressed_size FROM data WHERE data.book = ?"
	STMT_BOOKS_ID_ASC             = STMT_BOOKS0 + " ORDER BY id" + STMT_PAGE
	STMT_BOOKS_ID_DESC            = STMT_BOOKS0 + "ORDER BY id DESC" + STMT_PAGE
	STMT_BOOKS_TITLE_ASC          = STMT_BOOKS0 + "ORDER BY books.sort" + STMT_PAGE
	STMT_BOOKS_TITLE_DESC         = STMT_BOOKS0 + "ORDER BY books.sort DESC" + STMT_PAGE
	STMT_BOOKS_TAGS_ID_ASC        = STMT_BOOKS_TAGS0 + "ORDER BY id" + STMT_PAGE + ")"
	STMT_BOOKS_TAGS_ID_DESC       = STMT_BOOKS_TAGS0 + "ORDER BY id DESC" + STMT_PAGE + ")"
	STMT_BOOKS_TAGS_TITLE_ASC     = STMT_BOOKS_TAGS0 + "ORDER BY books.sort" + STMT_PAGE + ")"
	STMT_BOOKS_TAGS_TITLE_DESC    = STMT_BOOKS_TAGS0 + "ORDER BY books.sort DESC" + STMT_PAGE + ")"
	STMT_BOOKS_AUTHORS_ID_ASC     = STMT_BOOKS_AUTHORS0 + "ORDER BY id" + STMT_PAGE + ")"
	STMT_BOOKS_AUTHORS_ID_DESC    = STMT_BOOKS_AUTHORS0 + "ORDER BY id DESC" + STMT_PAGE + ")"
	STMT_BOOKS_AUTHORS_TITLE_ASC  = STMT_BOOKS_AUTHORS0 + "ORDER BY books.sort" + STMT_PAGE + ")"
	STMT_BOOKS_AUTHORS_TITLE_DESC = STMT_BOOKS_AUTHORS0 + "ORDER BY books.sort DESC" + STMT_PAGE + ")"

	DEF_LIM = 10
)

// MERGE SUB QUERIES //
func assignAuthorsTagsBooks(books []*BookAdv, authors map[int64][]*Author, tags map[int64][]string) {
	for _, b := range books {
		b.Authors = authors[b.Id]
		b.Tags = tags[b.Id]
	}
}

// SUB QUERIES //

func (app *Bouquins) queryBooks(limit, offset int) ([]*BookAdv, error) {
	books := make([]*BookAdv, 0, limit)
	stmt, err := app.DB.Prepare(STMT_BOOKS_ID_ASC)
	if err != nil {
		return nil, err
	}
	rows, err := stmt.Query(limit, offset)
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		book := new(BookAdv)
		var series_name sql.NullString
		var series_id sql.NullInt64
		if err := rows.Scan(&book.Id, &book.Title, &book.SeriesIndex, &series_name, &series_id); err != nil {
			return nil, err
		}
		if series_name.Valid && series_id.Valid {
			book.Series = &Series{
				series_id.Int64,
				series_name.String,
			}
		}
		books = append(books, book)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	return books, nil
}

func (app *Bouquins) queryBooksAuthors(limit, offset int) (map[int64][]*Author, error) {
	authors := make(map[int64][]*Author)
	stmt, err := app.DB.Prepare(STMT_BOOKS_AUTHORS_ID_ASC)
	if err != nil {
		return nil, err
	}
	rows, err := stmt.Query(limit, offset)
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		author := new(Author)
		var book int64
		if err := rows.Scan(&author.Id, &author.Name, &book); err != nil {
			return nil, err
		}
		if authors[book] == nil {
			authors[book] = append(make([]*Author, 0), author)
		} else {
			authors[book] = append(authors[book], author)
		}
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	return authors, nil
}

func (app *Bouquins) queryBooksTags(limit, offset int) (map[int64][]string, error) {
	tags := make(map[int64][]string)
	stmt, err := app.DB.Prepare(STMT_BOOKS_TAGS_ID_ASC)
	if err != nil {
		return nil, err
	}
	rows, err := stmt.Query(limit, offset)
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		var tag string
		var book int64
		if err := rows.Scan(&tag, &book); err != nil {
			return nil, err
		}
		bookTags := tags[book]
		if bookTags == nil {
			bookTags = make([]string, 1)
			tags[book] = bookTags
		}
		tags[book] = append(bookTags, tag)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	return tags, nil
}

// DB LOADS //

func (app *Bouquins) BookCount() (int64, error) {
	var count int64
	row := app.DB.QueryRow(STMT_BOOKS_COUNT)
	err := row.Scan(&count)
	return count, err
}

func (app *Bouquins) BooksAdv(limit int, offset int) ([]*BookAdv, error) {
	if limit == 0 {
		limit = DEF_LIM
	}
	books, err := app.queryBooks(limit, offset)
	if err != nil {
		return nil, err
	}
	authors, err := app.queryBooksAuthors(limit, offset)
	if err != nil {
		return nil, err
	}
	tags, err := app.queryBooksTags(limit, offset)
	if err != nil {
		return nil, err
	}
	assignAuthorsTagsBooks(books, authors, tags)
	return books, nil
}