"""Helpers used by more than one route module in this package.

Nothing here touches the blueprint: these are plain functions, so a test
can call them with a request context and nothing else.
"""

from flask import flash, request
from flask_babel import gettext as _

from app.extensions import db
from app.models import Admin, Coach, Manager, Player, Scout, GAME_PLATFORMS, UserGamertag

ALLOWED_CONTRACT_EXTENSIONS = {'pdf'}
ALLOWED_SIGNED_EXTENSIONS = {'pdf'}

#: Every PDF starts with this. Checking the name alone accepted a file
#: called anything.pdf holding anything at all.
PDF_SIGNATURE = b'%PDF-'

#: USER_TYPE → model class, for create_user.
USER_CLASS_MAP = {
    'admin': Admin,
    'manager': Manager,
    'coach': Coach,
    'player': Player,
    'scout': Scout,
}


def pdf_upload_error(file, allowed_extensions):
    """Why this upload is not an acceptable PDF, or None if it is.

    upload_signed_contract checked nothing beyond a non-empty filename —
    ALLOWED_SIGNED_EXTENSIONS was declared and never read — so a player
    could put an arbitrary file on the server under a name the application
    later hands back for download (SEC-021).

    Args:
        file: The uploaded FileStorage, or None.
        allowed_extensions: Extensions to accept, lowercase and without dot.

    Returns:
        str | None: A message to flash, or None when the file is acceptable.
    """
    if file is None or not file.filename:
        return _('No file selected.')

    stem, dot, extension = file.filename.rpartition('.')
    if not (stem and dot) or extension.lower() not in allowed_extensions:
        return _('Only PDF files are allowed for contracts.')

    head = file.stream.read(len(PDF_SIGNATURE))
    file.stream.seek(0)
    if head != PDF_SIGNATURE:
        return _('That file is not a PDF, whatever its name says.')

    return None


def flash_validation_errors(err):
    """Surface marshmallow errors the same way auth.py already does."""
    for field, messages in err.messages.items():
        for msg in messages:
            flash(_('%(field)s: %(msg)s', field=field, msg=msg), 'danger')


def form_payload(*, checkboxes=(), list_fields=('games',), optional_blank=('password',)):
    """Turn the multi-valued request form into a plain dict for marshmallow.

    request.form.to_dict() keeps only the first value of a repeated key, so
    list fields have to be re-read with getlist(). Unchecked HTML checkboxes
    are simply absent from the submission, which is not the same as a schema
    default, so they are injected explicitly. Blank optional fields are
    dropped rather than sent as '' — an empty password means "leave the
    current one alone", not "set the password to the empty string".
    """
    payload = request.form.to_dict()
    for name in list_fields:
        payload[name] = request.form.getlist(name)
    for name in checkboxes:
        payload[name] = name in request.form
    for name in optional_blank:
        if not payload.get(name):
            payload.pop(name, None)
    return payload


def update_user_gamertags(user, selected_games):
    """Update gamertags for a user based on form input."""
    existing_gamertags = {gt.game: gt for gt in user.gamertags}
    for game in selected_games:
        gamertag = request.form.get(f'gamertag_{game}', '').strip()
        platform = (
            request.form.get(f'platform_{game}', '').strip() if GAME_PLATFORMS.get(game) else None
        )
        existing = existing_gamertags.get(game)
        if gamertag:
            if existing:
                existing.gamertag = gamertag
                existing.platform = platform
            else:
                gt = UserGamertag(user_id=user.id, game=game, gamertag=gamertag, platform=platform)
                db.session.add(gt)
        elif existing:
            db.session.delete(existing)
    for game in existing_gamertags:
        if game not in selected_games:
            db.session.delete(existing_gamertags[game])