#!/usr/bin/env python3
"""Модуль для работы с авторами"""
from db_utils import get_cursor


def get_authors_by_prefix(prefix=''):
    """Возвращает авторов по префиксу фамилии"""
    conn, cur = get_cursor()

    if prefix:
        cur.execute("""
            SELECT a.id, a.full_name, a.name_hash,
                   COUNT(DISTINCT ba.book_id) as books_count
            FROM authors a
            LEFT JOIN book_authors ba ON ba.author_id = a.id
            WHERE a.last_name ILIKE %s
            GROUP BY a.id, a.full_name, a.name_hash
            ORDER BY a.last_name, a.first_name
            LIMIT 100
        """, (prefix + '%',))
    else:
        cur.execute("""
            SELECT DISTINCT lower(substring(last_name, 1, 1)) as letter,
                   COUNT(*) as cnt
            FROM authors
            WHERE last_name ~ '^[а-яА-Яa-zA-Z]'
            GROUP BY lower(substring(last_name, 1, 1))
            ORDER BY letter
        """)

    result = cur.fetchall()
    conn.close()
    return result


def get_author_prefixes(prefix=''):
    """Возвращает группировку по следующим буквам"""
    conn, cur = get_cursor()

    next_len = len(prefix) + 1
    cur.execute("""
        SELECT DISTINCT
            substring(last_name, %s, 1) as next_letter,
            COUNT(*) as cnt,
            MIN(last_name) as first_author,
            MAX(last_name) as last_author
        FROM authors
        WHERE last_name ILIKE %s
        GROUP BY substring(last_name, %s, 1)
        ORDER BY next_letter
    """, (next_len, prefix + '%', next_len))

    result = cur.fetchall()
    conn.close()
    return result


def get_author_by_hash(author_hash):
    """Возвращает автора по хешу"""
    conn, cur = get_cursor()

    cur.execute("""
        SELECT id, full_name, last_name, first_name, middle_name, name_hash
        FROM authors
        WHERE name_hash = %s
    """, (author_hash,))

    author = cur.fetchone()
    conn.close()
    return author


def get_author_series(author_id):
    """Возвращает серии автора"""
    conn, cur = get_cursor()

    cur.execute("""
        SELECT DISTINCT s.id, s.name, s.name_hash,
               COUNT(DISTINCT b.id) as books_count
        FROM series s
        JOIN books b ON b.series_id = s.id
        JOIN book_authors ba ON ba.book_id = b.id
        WHERE ba.author_id = %s
        GROUP BY s.id, s.name, s.name_hash
        ORDER BY s.name
    """, (author_id,))

    series = cur.fetchall()
    conn.close()
    return series


def get_author_books(author_id):
    """Возвращает книги автора (без серий)"""
    conn, cur = get_cursor()

    # Простой запрос без string_agg
    cur.execute("""
        SELECT b.id, b.title, b.language, b.added_date, b.series_number,
               s.name as series_name, s.name_hash as series_hash
        FROM books b
        JOIN book_authors ba ON ba.book_id = b.id
        LEFT JOIN series s ON s.id = b.series_id
        WHERE ba.author_id = %s
        GROUP BY b.id, b.title, b.language, b.added_date, b.series_number,
                 s.name, s.name_hash
        ORDER BY b.added_date DESC NULLS LAST
    """, (author_id,))

    books = cur.fetchall()

    # Для каждой книги получаем количество авторов и соавторов
    for book in books:
        cur.execute("""
            SELECT COUNT(*) as cnt
            FROM book_authors
            WHERE book_id = %s
        """, (book['id'],))
        book['authors_count'] = cur.fetchone()['cnt']

        cur.execute("""
            SELECT string_agg(a.full_name, ', ' ORDER BY ba.position) as coauthors
            FROM book_authors ba
            JOIN authors a ON a.id = ba.author_id
            WHERE ba.book_id = %s
        """, (book['id'],))
        book['coauthors'] = cur.fetchone()['coauthors']

    conn.close()
    return books


def get_series_books(series_id):
    """Возвращает все книги серии"""
    conn, cur = get_cursor()

    cur.execute("""
        SELECT b.id, b.title, b.language, b.series_number,
               string_agg(DISTINCT a.full_name, ', ' ORDER BY ba.position) as authors
        FROM books b
        JOIN book_authors ba ON ba.book_id = b.id
        JOIN authors a ON a.id = ba.author_id
        WHERE b.series_id = %s
        GROUP BY b.id, b.title, b.language, b.series_number
        ORDER BY b.series_number
    """, (series_id,))

    books = cur.fetchall()
    conn.close()
    return books