"""Book download manager handling search and retrieval operations."""

import time, json, re
from pathlib import Path
from urllib.parse import quote
from typing import List, Optional, Dict, Union, Callable
from threading import Event
from bs4 import BeautifulSoup, Tag, NavigableString, ResultSet

import downloader
from logger import setup_logger
from config import SUPPORTED_FORMATS, BOOK_LANGUAGE, AA_BASE_URL
from env import AA_DONATOR_KEY, USE_CF_BYPASS, PRIORITIZE_WELIB
from models import BookInfo, SearchFilters
logger = setup_logger(__name__)



def search_books(query: str, filters: SearchFilters) -> List[BookInfo]:
    """Search for books matching the query.

    Args:
        query: Search term (ISBN, title, author, etc.)

    Returns:
        List[BookInfo]: List of matching books

    Raises:
        Exception: If no books found or parsing fails
    """
    query_html = quote(query)

    if filters.isbn:
        # ISBNs are included in query string
        isbns = " || ".join(
            [f"('isbn13:{isbn}' || 'isbn10:{isbn}')" for isbn in filters.isbn]
        )
        query_html = quote(f"({isbns}) {query}")

    filters_query = ""

    for value in filters.lang or BOOK_LANGUAGE:
        if value != "all":
            filters_query += f"&lang={quote(value)}"

    if filters.sort:
        filters_query += f"&sort={quote(filters.sort)}"

    if filters.content:
        for value in filters.content:
            filters_query += f"&content={quote(value)}"

    # Handle format filter
    formats_to_use = filters.format if filters.format else SUPPORTED_FORMATS

    index = 1
    for filter_type, filter_values in vars(filters).items():
        if filter_type == "author" or filter_type == "title" and filter_values:
            for value in filter_values:
                filters_query += (
                    f"&termtype_{index}={filter_type}&termval_{index}={quote(value)}"
                )
                index += 1

    url = (
        f"{AA_BASE_URL}"
        f"/search?index=&page=1&display=table"
        f"&acc=aa_download&acc=external_download"
        f"&ext={'&ext='.join(formats_to_use)}"
        f"&q={query_html}"
        f"{filters_query}"
    )

    html = downloader.html_get_page(url)
    if not html:
        raise Exception("Failed to fetch search results")

    if "No files found." in html:
        logger.info(f"No books found for query: {query}")
        raise Exception("No books found. Please try another query.")

    soup = BeautifulSoup(html, "html.parser")
    tbody: Tag | NavigableString | None = soup.find("table")

    if not tbody:
        logger.warning(f"No results table found for query: {query}")
        raise Exception("No books found. Please try another query.")

    books = []
    if isinstance(tbody, Tag):
        for line_tr in tbody.find_all("tr"):
            try:
                book = _parse_search_result_row(line_tr)
                if book:
                    books.append(book)
            except Exception as e:
                logger.error_trace(f"Failed to parse search result row: {e}")

    books.sort(
        key=lambda x: (
            SUPPORTED_FORMATS.index(x.format)
            if x.format in SUPPORTED_FORMATS
            else len(SUPPORTED_FORMATS)
        )
    )

    return books


def _parse_search_result_row(row: Tag) -> Optional[BookInfo]:
    """Parse a single search result row into a BookInfo object."""
    try:
        cells = row.find_all("td")
        preview_img = cells[0].find("img")
        preview = preview_img["src"] if preview_img else None

        return BookInfo(
            id=row.find_all("a")[0]["href"].split("/")[-1],
            preview=preview,
            title=cells[1].find("span").next,
            author=cells[2].find("span").next,
            publisher=cells[3].find("span").next,
            year=cells[4].find("span").next,
            language=cells[7].find("span").next,
            format=cells[9].find("span").next.lower(),
            size=cells[10].find("span").next,
        )
    except Exception as e:
        logger.error_trace(f"Error parsing search result row: {e}")
        return None


def get_book_info(book_id: str) -> BookInfo:
    """Get detailed information for a specific book.

    Args:
        book_id: Book identifier (MD5 hash)

    Returns:
        BookInfo: Detailed book information
    """
    url = f"{AA_BASE_URL}/md5/{book_id}"
    html = downloader.html_get_page(url)

    if not html:
        raise Exception(f"Failed to fetch book info for ID: {book_id}")

    soup = BeautifulSoup(html, "html.parser")

    return _parse_book_info_page(soup, book_id)


def _parse_book_info_page(soup: BeautifulSoup, book_id: str) -> BookInfo:
    """Parse the book info page HTML into a BookInfo object."""
    data = soup.select_one("body > main > div:nth-of-type(1)")

    if not data:
        raise Exception(f"Failed to parse book info for ID: {book_id}")

    preview: str = ""

    node = data.select_one("div:nth-of-type(1) > img")
    if node:
        preview_value = node.get("src", "")
        if isinstance(preview_value, list):
            preview = preview_value[0]
        else:
            preview = preview_value

    data = soup.find_all("div", {"class": "main-inner"})[0].find_next("div")
    divs = list(data.children)
    _details = divs[13].text.strip().lower().split(" · ")
    format = ""
    size = ""
    for f in _details:
        if format == "" and f.strip().lower() in SUPPORTED_FORMATS:
            format = f.strip().lower()
        if size == "" and any(u in f.strip().lower() for u in ["mb", "kb", "gb"]):
            size = f.strip().lower()

    if format == "" or size == "":
        for f in _details:
            if f == "" and not " " in f.strip().lower():
                format = f.strip().lower()
            if size == "" and "." in f.strip().lower():
                size = f.strip().lower()

    every_url = soup.find_all("a")
    slow_urls_no_waitlist = set()
    slow_urls_with_waitlist = set()
    external_urls_libgen = set()
    external_urls_z_lib = set()
    external_urls_welib = set()

    for url in every_url:
        try:
            if url.text.strip().lower().startswith("slow partner server"):
                if (
                    url.next is not None
                    and url.next.next is not None
                    and "waitlist" in url.next.next.strip().lower()
                ):
                    internal_text = url.next.next.strip().lower()
                    if "no waitlist" in internal_text:
                        slow_urls_no_waitlist.add(url["href"])
                    else:
                        slow_urls_with_waitlist.add(url["href"])
            elif (
                url.next is not None
                and url.next.next is not None
                and "click “GET” at the top" in url.next.next.text.strip()
            ):
                libgen_url = url["href"]
                # TODO : Temporary fix ? Maybe get URLs from https://open-slum.org/ ?
                libgen_url = re.sub(r'libgen\.(lc|is|bz|st)', 'libgen.gl', url["href"])

                external_urls_libgen.add(libgen_url)
            elif url.text.strip().lower().startswith("z-lib"):
                if ".onion/" not in url["href"]:
                    external_urls_z_lib.add(url["href"])
        except:
            pass

    external_urls_welib = _get_download_urls_from_welib(book_id) if USE_CF_BYPASS else set()

    urls = []
    urls += list(external_urls_welib) if PRIORITIZE_WELIB else []
    urls += list(slow_urls_no_waitlist) if USE_CF_BYPASS else []
    urls += list(external_urls_libgen)
    urls += list(external_urls_welib) if not PRIORITIZE_WELIB else []
    urls += list(slow_urls_with_waitlist)  if USE_CF_BYPASS else []
    urls += list(external_urls_z_lib)

    for i in range(len(urls)):
        urls[i] = downloader.get_absolute_url(AA_BASE_URL, urls[i])

    # Remove empty urls
    urls = [url for url in urls if url != ""]

    # Extract basic information
    book_info = BookInfo(
        id=book_id,
        preview=preview,
        title=divs[7].text.strip(),
        publisher=divs[11].text.strip(),
        author=divs[9].text.strip(),
        format=format,
        size=size,
        download_urls=urls,
    )

    # Extract additional metadata
    info = _extract_book_metadata(divs[-6])
    book_info.info = info

    # Set language and year from metadata if available
    if info.get("Language"):
        book_info.language = info["Language"][0]
    if info.get("Year"):
        book_info.year = info["Year"][0]

    return book_info

def _get_download_urls_from_welib(book_id: str) -> set[str]:
    """Get download urls from welib.org."""
    url = f"https://welib.org/md5/{book_id}"
    logger.info(f"Getting download urls from welib.org for {book_id}. While this uses the bypasser, it will not start downloading them yet.")
    html = downloader.html_get_page(url, use_bypasser=True)
    if not html:
        return []
    soup = BeautifulSoup(html, "html.parser")
    download_links = soup.find_all("a", href=True)
    download_links = [link["href"] for link in download_links]
    download_links = [link for link in download_links if "/slow_download/" in link]
    download_links = [downloader.get_absolute_url(url, link) for link in download_links]
    return set(download_links)

def _extract_book_metadata(
    metadata_divs
) -> Dict[str, List[str]]:
    """Extract metadata from book info divs."""
    info: Dict[str, List[str]] = {}

    # Process the first set of metadata
    sub_datas = metadata_divs.find_all("div")[0]
    sub_datas = list(sub_datas.children)
    for sub_data in sub_datas:
        if sub_data.text.strip() == "":
            continue
        sub_data = list(sub_data.children)
        key = sub_data[0].text.strip()
        value = sub_data[1].text.strip()
        if key not in info:
            info[key] = set()
        info[key].add(value)
    
    # make set into list
    for key, value in info.items():
        info[key] = list(value)

    # Filter relevant metadata
    relevant_prefixes = [
        "ISBN-",
        "ALTERNATIVE",
        "ASIN",
        "Goodreads",
        "Language",
        "Year",
    ]
    return {
        k.strip(): v
        for k, v in info.items()
        if any(k.lower().startswith(prefix.lower()) for prefix in relevant_prefixes)
        and "filename" not in k.lower()
    }


def download_book(book_info: BookInfo, book_path: Path, progress_callback: Optional[Callable[[float], None]] = None, cancel_flag: Optional[Event] = None) -> bool:
    """Download a book from available sources.

    Args:
        book_id: Book identifier (MD5 hash)
        title: Book title for logging

    Returns:
        Optional[BytesIO]: Book content buffer if successful
    """

    if len(book_info.download_urls) == 0:
        book_info = get_book_info(book_info.id)
    download_links = book_info.download_urls

    # If AA_DONATOR_KEY is set, use the fast download URL. Else try other sources.
    if AA_DONATOR_KEY != "":
        download_links.insert(
            0,
            f"{AA_BASE_URL}/dyn/api/fast_download.json?md5={book_info.id}&key={AA_DONATOR_KEY}",
        )

    for link in download_links:
        try:
            download_url = _get_download_url(link, book_info.title, cancel_flag)
            if download_url != "":
                logger.info(f"Downloading `{book_info.title}` from `{download_url}`")

                data = downloader.download_url(download_url, book_info.size or "", progress_callback, cancel_flag)
                if not data:
                    raise Exception("No data received")

                logger.info(f"Download finished. Writing to {book_path}")
                with open(book_path, "wb") as f:
                    f.write(data.getbuffer())
                logger.info(f"Writing `{book_info.title}` successfully")
                return True

        except Exception as e:
            logger.error_trace(f"Failed to download from {link}: {e}")
            continue

    return False


def _get_download_url(link: str, title: str, cancel_flag: Optional[Event] = None) -> str:
    """Extract actual download URL from various source pages."""

    url = ""

    if link.startswith(f"{AA_BASE_URL}/dyn/api/fast_download.json"):
        page = downloader.html_get_page(link)
        url = json.loads(page).get("download_url")
    else:
        html = downloader.html_get_page(link)

        if html == "":
            return ""

        soup = BeautifulSoup(html, "html.parser")

        if link.startswith("https://z-lib."):
            download_link = soup.find_all("a", href=True, class_="addDownloadedBook")
            if download_link:
                url = download_link[0]["href"]
        elif "/slow_download/" in link:
            download_links = soup.find_all("a", href=True, string="📚 Download now")
            if not download_links:
                countdown = soup.find_all("span", class_="js-partner-countdown")
                if countdown:
                    sleep_time = int(countdown[0].text)
                    logger.info(f"Waiting {sleep_time}s for {title}")
                    if cancel_flag is not None and cancel_flag.wait(timeout=sleep_time):
                        logger.info(f"Cancelled wait for {title}")
                        return ""
                    url = _get_download_url(link, title, cancel_flag)
            else:
                url = download_links[0]["href"]
        else:
            url = soup.find_all("a", string="GET")[0]["href"]

    return downloader.get_absolute_url(link, url)