"""Input validation schemas for the Team Tryouts application.

This module provides Marshmallow schemas for validating and sanitizing
all user inputs including forms, JSON requests, and file uploads.
All validation is centralized here for consistency and maintainability.

Usage:
    from validators import LoginSchema
    schema = LoginSchema()
    errors = schema.validate(request.form)
"""

import re

from flask_babel import lazy_gettext as _l
from marshmallow import (
    EXCLUDE,
    Schema,
    ValidationError,
    fields,
    pre_load,
    validate,
    validates_schema,
)

from app.models import ESPORT_GAMES, USER_TYPES

# =============================================================================
# Custom Validators
# =============================================================================

PASSWORD_POLICY = re.compile(r'^(?=.*[a-z])(?=.*[A-Z])(?=.*\d).{8,}$')
"""Password policy: minimum 8 chars, 1 uppercase, 1 lowercase, 1 digit."""


def validate_password(value):
    """Validate password meets strength requirements.

    Requires: minimum 8 characters, at least one uppercase letter,
    one lowercase letter, and one digit.

    Args:
        value: The password string to validate.

    Raises:
        ValidationError: If password does not meet requirements.
    """
    if not PASSWORD_POLICY.match(value):
        raise ValidationError(
            _l('Password must be at least 8 characters with uppercase, lowercase, and a number.')
        )


def validate_username(value):
    """Validate username format.

    Usernames must be 3-30 characters and contain only alphanumeric
    characters, underscores, and hyphens.

    Args:
        value: The username string to validate.

    Raises:
        ValidationError: If username does not meet requirements.
    """
    if not re.match(r'^[a-zA-Z0-9_-]{3,30}$', value):
        raise ValidationError(
            _l('Username must be 3-30 characters (letters, numbers, underscore, hyphen).')
        )


def validate_discord_username(value):
    """Validate Discord username format if provided.

    Accepts empty strings (optional field). Validates that the username
    matches common Discord username patterns.

    Args:
        value: The Discord username to validate.

    Raises:
        ValidationError: If the format is invalid.
    """
    if not value:
        return
    if not re.match(r'^[a-zA-Z0-9_.]{2,32}$', value):
        raise ValidationError(_l('Invalid Discord username format.'))


def validate_discord_user_id(value):
    """Validate Discord user ID (snowflake) if provided.

    Discord user IDs are 17-20 digit numbers.

    Args:
        value: The Discord user ID to validate.

    Raises:
        ValidationError: If the format is invalid.
    """
    if not value:
        return
    if not re.match(r'^\d{17,20}$', value):
        raise ValidationError(_l('Discord User ID must be a 17-20 digit number.'))


def validate_phone(value):
    """Validate optional phone number format.

    Accepts empty strings. Validates common phone formats.

    Args:
        value: The phone number to validate.

    Raises:
        ValidationError: If the format is invalid.
    """
    if not value:
        return
    cleaned = re.sub(r'[\s\-\(\)\.]', '', value)
    if not re.match(r'^\+?\d{7,15}$', cleaned):
        raise ValidationError(_l('Invalid phone number format.'))


# =============================================================================
# Validation Schemas
# =============================================================================


class StripMixin(Schema):
    """Mixin that automatically strips whitespace from all string fields
    and ignores unknown fields (e.g., csrf_token from Flask-WTF)."""

    class Meta:
        """Marshmallow Meta options."""

        unknown = EXCLUDE  # Ignore csrf_token and other unknown fields

    @pre_load
    def normalise_form_values(self, data, **kwargs):
        """Strip whitespace, and read an empty input as an absent one.

        Both halves in one hook rather than two: marshmallow gives no
        ordering guarantee between several pre_load hooks on the same schema,
        and these two have to happen in this order.

        The second half is what let the match and tryout forms be validated
        at all (ARCH-005). An HTML form submits every field it renders, so an
        untouched optional date arrives as '' rather than not arriving —
        and '' is not a date, so a schema written the obvious way rejected
        every form with a blank optional field. Dropping the key instead lets
        `load_default` do its job.

        Only fields the schema declares as optional are dropped. A blank
        *required* field still has to fail, and say so.

        Args:
            data: The input dictionary.

        Returns:
            dict: Data with stripped strings and blank optionals removed.
        """
        if not isinstance(data, dict):
            return data

        stripped = {k: v.strip() if isinstance(v, str) else v for k, v in data.items()}
        return {
            key: value
            for key, value in stripped.items()
            if value != '' or self._is_required(key) or self._accepts_blank(key)
        }

    def _is_required(self, key):
        field = self.fields.get(key)
        return field is not None and field.required

    def _accepts_blank(self, key):
        """True when '' is a value this field means to receive.

        A plain String is one: `description=''` on an edit form means "clear
        the description", not "leave it alone". An Email is not — there is no
        such thing as an empty address, so a blank one is an absent one.

        Typed fields (Integer, Date, Time, List) are not Strings and so are
        never kept blank, which is the whole point of the hook.
        """
        field = self.fields.get(key)
        return isinstance(field, fields.String) and not isinstance(field, fields.Email)


class LoginSchema(StripMixin):
    """Validate login form input.

    Fields:
        username: 3-30 chars, required.
        password: Non-empty, required.
    """

    username = fields.String(
        required=True,
        validate=validate.Length(min=1, max=80, error=_l('Username is required.')),
    )
    password = fields.String(
        required=True,
        validate=validate.Length(min=1, error=_l('Password is required.')),
    )


class RegisterSchema(StripMixin):
    """Validate player registration form input.

    Fields:
        username: 3-30 chars alphanumeric, required.
        email: Valid email, required.
        password: Meets password policy, required.
        confirm_password: Must match password, required.
        full_name: 1-100 chars, required.
        phone: Optional, valid phone format.
        games: Optional list.
        discord_username: Optional, valid format.
        league_os_profile: Optional URL.
    """

    username = fields.String(
        required=True,
        validate=[
            validate.Length(min=3, max=80, error=_l('Username must be 3-80 characters.')),
            validate_username,
        ],
    )
    email = fields.Email(
        required=True,
        validate=validate.Length(max=120, error=_l('Email must be 120 characters or less.')),
    )
    password = fields.String(
        required=True,
        validate=validate_password,
        load_only=True,
    )
    confirm_password = fields.String(
        required=True,
        load_only=True,
    )
    full_name = fields.String(
        required=True,
        validate=validate.Length(min=1, max=100, error=_l('Full name is required.')),
    )
    phone = fields.String(
        validate=validate_phone,
        allow_none=True,
        load_default=None,
    )
    games = fields.List(fields.String(), load_default=[])
    discord_username = fields.String(
        validate=validate_discord_username,
        allow_none=True,
        load_default=None,
    )
    discord_user_id = fields.String(
        validate=validate_discord_user_id,
        allow_none=True,
        load_default=None,
    )
    league_os_profile = fields.String(
        validate=validate.Length(max=256),
        allow_none=True,
        load_default=None,
    )

    @validates_schema
    def validate_password_match(self, data, **kwargs):
        """Ensure confirm_password matches password.

        Args:
            data: The validated data dictionary.

        Raises:
            ValidationError: If passwords do not match.
        """
        if data.get('password') != data.get('confirm_password'):
            raise ValidationError(_l('Passwords do not match.'), field_name='confirm_password')


class CreateUserSchema(StripMixin):
    """Validate president-created user form input.

    Fields:
        username: 3-30 chars alphanumeric, required.
        email: Valid email, required.
        password: Meets password policy, required.
        full_name: 1-100 chars, required.
        role: Must be valid role, required.
        phone: Optional, valid phone format.
    """

    username = fields.String(
        required=True,
        validate=[
            validate.Length(min=3, max=80, error=_l('Username must be 3-80 characters.')),
            validate_username,
        ],
    )
    email = fields.Email(
        required=True,
        validate=validate.Length(max=120),
    )
    password = fields.String(
        required=True,
        validate=validate_password,
        load_only=True,
    )
    full_name = fields.String(
        required=True,
        validate=validate.Length(min=1, max=100, error=_l('Full name is required.')),
    )
    role = fields.String(
        required=True,
        validate=validate.OneOf(USER_TYPES, error=_l('Invalid role selected.')),
    )
    phone = fields.String(
        validate=validate_phone,
        allow_none=True,
        load_default=None,
    )


class EditUserSchema(StripMixin):
    """Validate president-edited user form input.

    Fields:
        full_name: 1-100 chars, required.
        email: Valid email, required.
        role: Must be valid role, required.
        is_active_account: Boolean.
        phone: Optional.
        password: Optional (only if changing).
        discord_username: Optional.
        discord_user_id: Optional.
        league_os_profile: Optional.
        games: Optional list.
    """

    full_name = fields.String(
        required=True,
        validate=validate.Length(min=1, max=100, error=_l('Full name is required.')),
    )
    email = fields.Email(
        required=True,
        validate=validate.Length(max=120),
    )
    role = fields.String(
        required=True,
        validate=validate.OneOf(USER_TYPES, error=_l('Invalid role selected.')),
    )
    is_active_account = fields.Boolean(load_default=True)
    phone = fields.String(
        validate=validate_phone,
        allow_none=True,
        load_default=None,
    )
    password = fields.String(
        validate=validate_password,
        load_only=True,
        allow_none=True,
        load_default='',
    )
    discord_username = fields.String(
        validate=validate_discord_username,
        allow_none=True,
        load_default=None,
    )
    discord_user_id = fields.String(
        validate=validate_discord_user_id,
        allow_none=True,
        load_default=None,
    )
    league_os_profile = fields.String(
        validate=validate.Length(max=256),
        allow_none=True,
        load_default=None,
    )
    games = fields.List(fields.String(), load_default=[])


class EditProfileSchema(StripMixin):
    """Validate self-edit profile form input.

    Fields:
        username: 3-30 chars, required.
        full_name: 1-100 chars, required.
        email: Valid email, required.
        phone: Optional.
        password: Optional (only if changing).
        discord_username: Optional.
        discord_user_id: Optional.
        league_os_profile: Optional.
        games: Optional list.
    """

    username = fields.String(
        required=True,
        validate=[
            validate.Length(min=3, max=80),
            validate_username,
        ],
    )
    full_name = fields.String(
        required=True,
        validate=validate.Length(min=1, max=100, error=_l('Full name is required.')),
    )
    email = fields.Email(
        required=True,
        validate=validate.Length(max=120),
    )
    phone = fields.String(
        validate=validate_phone,
        allow_none=True,
        load_default=None,
    )
    password = fields.String(
        validate=validate_password,
        load_only=True,
        allow_none=True,
        load_default='',
    )
    discord_username = fields.String(
        validate=validate_discord_username,
        allow_none=True,
        load_default=None,
    )
    discord_user_id = fields.String(
        validate=validate_discord_user_id,
        allow_none=True,
        load_default=None,
    )
    league_os_profile = fields.String(
        validate=validate.Length(max=256),
        allow_none=True,
        load_default=None,
    )
    games = fields.List(fields.String(), load_default=[])


class UploadContractSchema(StripMixin):
    """Validate contract upload form input.

    Fields:
        player_id: Integer, required.
        notes: Optional text.
    """

    player_id = fields.Integer(
        required=True,
        validate=validate.Range(min=1, error=_l('Player must be selected.')),
    )
    notes = fields.String(
        validate=validate.Length(max=2000, error=_l('Notes must be 2000 characters or less.')),
        allow_none=True,
        load_default=None,
    )


class OneOnOneRequestSchema(StripMixin):
    """Validate One on One session request form input.

    Fields:
        date: Date string (YYYY-MM-DD), required.
        start_time: Time string (HH:MM), required.
        end_time: Time string (HH:MM), required.
        points: Optional text.
    """

    date = fields.String(
        required=True,
        validate=validate.Regexp(
            r'^\d{4}-\d{2}-\d{2}$', error=_l('Date must be in YYYY-MM-DD format.')
        ),
    )
    start_time = fields.String(
        required=True,
        validate=validate.Regexp(r'^\d{2}:\d{2}$', error=_l('Start time must be in HH:MM format.')),
    )
    end_time = fields.String(
        required=True,
        validate=validate.Regexp(r'^\d{2}:\d{2}$', error=_l('End time must be in HH:MM format.')),
    )
    points = fields.String(
        validate=validate.Length(max=2000, error=_l('Points must be 2000 characters or less.')),
        allow_none=True,
        load_default=None,
    )


class DisponibilityAddSchema(StripMixin):
    """Validate disponibility block addition.

    Fields:
        day_of_week: Integer 0-6, required.
        start_time: Time string (HH:MM), required.
    """

    day_of_week = fields.Integer(
        required=True,
        validate=validate.Range(min=0, max=6, error=_l('Day must be 0 (Monday) to 6 (Sunday).')),
    )
    start_time = fields.String(
        required=True,
        validate=validate.Regexp(r'^\d{2}:\d{2}$', error=_l('Start time must be in HH:MM format.')),
    )


# =============================================================================
# Scheduling — matches and tryouts (ARCH-005)
# =============================================================================

#: The three shapes a tryout match can take. Read by the route to decide how
#: participants are drawn; a value outside this set produced a match with no
#: participants at all and no complaint.
MATCH_TYPES = ('team_vs_team', 'player_vs_player', 'player_scrim')

#: Match lifecycle. Was checked with an inline `if status in [...]` that
#: silently kept the old value on anything else.
MATCH_STATUSES = ('scheduled', 'completed', 'cancelled')


class CommaSeparatedIds(fields.Field):
    """A hidden input holding '3,7,12' — ids picked in the page.

    The match form posts its player selections this way. Every route parsed
    it by hand, and each did it slightly differently: one dropped empty
    segments, another did not, a third called int() on whatever came out and
    would have raised a 500 on 'a,b'.
    """

    default_error_messages = {'invalid': _l('Player selection is malformed.')}

    def _deserialize(self, value, attr, data, **kwargs):
        if value is None or value == '':
            return []
        if isinstance(value, (list, tuple)):
            parts = value
        else:
            parts = str(value).split(',')
        try:
            return [int(part) for part in (str(p).strip() for p in parts) if part]
        except (TypeError, ValueError) as exc:
            raise self.make_error('invalid') from exc


class ScheduledEventSchema(StripMixin):
    """What every scheduled thing has: a title, a day, and a window on it.

    Shared by matches and team matches, which is also what BaseMatch says at
    the model level. Times are real time objects here rather than strings —
    the point of validating at the boundary is that a route never handles a
    '18:00' again.
    """

    title = fields.String(
        required=True,
        validate=validate.Length(min=1, max=200, error=_l('A title is required.')),
    )
    description = fields.String(
        validate=validate.Length(max=5000),
        allow_none=True,
        load_default=None,
    )
    date = fields.Date(
        required=True,
        error_messages={'invalid': _l('Invalid date format.')},
    )
    start_time = fields.Time(
        required=True,
        error_messages={
            'invalid': _l('Invalid time format.'),
            'required': _l('Start time is required. Please select a time slot.'),
        },
    )
    end_time = fields.Time(
        allow_none=True,
        load_default=None,
        error_messages={'invalid': _l('Invalid time format.')},
    )
    location = fields.String(
        validate=validate.Length(max=200),
        allow_none=True,
        load_default=None,
    )
    status = fields.String(
        validate=validate.OneOf(MATCH_STATUSES, error=_l('Unknown match status.')),
        load_default='scheduled',
    )

    @validates_schema
    def validate_window(self, data, **kwargs):
        """An event cannot end before it starts.

        Nothing checked this. A match from 20:00 to 18:00 was accepted, shown
        on the calendar as a negative-length block, and announced by Discord
        as exactly that.
        """
        start = data.get('start_time')
        end = data.get('end_time')
        if start and end and end <= start:
            raise ValidationError(
                _l('The end time must come after the start time.'), field_name='end_time'
            )


class MatchSchema(ScheduledEventSchema):
    """A match inside a tryout.

    match_type is required on creation and immutable afterwards — the edit
    form posts it as a hidden field and the route reads it off the record,
    not off the form.
    """

    match_type = fields.String(
        required=True,
        validate=validate.OneOf(MATCH_TYPES, error=_l('Unknown match type.')),
    )
    team1_id = fields.Integer(allow_none=True, load_default=None)
    team2_id = fields.Integer(allow_none=True, load_default=None)
    team1_player_ids = CommaSeparatedIds(load_default=list)
    team2_player_ids = CommaSeparatedIds(load_default=list)
    player_ids = fields.List(fields.Integer(), load_default=list)

    @validates_schema
    def validate_sides(self, data, **kwargs):
        """A team cannot play itself."""
        if data.get('team1_id') and data.get('team1_id') == data.get('team2_id'):
            raise ValidationError(_l('A team cannot play against itself.'), field_name='team2_id')


class MatchEditSchema(MatchSchema):
    """The same match, being edited.

    match_type is not accepted here at all: it decides how participants are
    drawn, and changing it on an existing match would leave the old ones
    behind. The route takes it from the record.
    """

    match_type = fields.String(load_default=None)


class TeamMatchSchema(ScheduledEventSchema):
    """A regular-season match for an organisation team."""

    opponent = fields.String(
        validate=validate.Length(max=200),
        allow_none=True,
        load_default=None,
    )
    is_practice = fields.Boolean(load_default=False)


class TryoutSchema(StripMixin):
    """A tryout event, created or edited.

    `game` is checked against ESPORT_GAMES: it drives the position list and
    the gamertag fields shown to registering players, so an unknown value
    produced a tryout nobody could be evaluated for. It was accepted as any
    string.

    `max_players` was `int(x) if x else None`, which raised on 'twelve' and
    happily stored -3.
    """

    title = fields.String(
        required=True,
        validate=validate.Length(min=1, max=200, error=_l('A title is required.')),
    )
    description = fields.String(
        validate=validate.Length(max=5000),
        allow_none=True,
        load_default=None,
    )
    game = fields.String(
        required=True,
        validate=validate.OneOf(ESPORT_GAMES, error=_l('Unknown game.')),
    )
    date = fields.Date(
        required=True,
        error_messages={
            'invalid': _l('Invalid start date format.'),
            'required': _l('A start date is required.'),
        },
    )
    end_date = fields.Date(
        allow_none=True,
        load_default=None,
        error_messages={'invalid': _l('Invalid end date format.')},
    )
    location = fields.String(
        validate=validate.Length(max=200),
        allow_none=True,
        load_default=None,
    )
    max_players = fields.Integer(
        validate=validate.Range(min=1, error=_l('A tryout must allow at least one player.')),
        allow_none=True,
        load_default=None,
        error_messages={'invalid': _l('The player limit must be a whole number.')},
    )
    target_org_team_id = fields.Integer(allow_none=True, load_default=None)
    manager_id = fields.Integer(allow_none=True, load_default=None)
    coach_ids = fields.List(fields.Integer(), load_default=list)

    @validates_schema
    def validate_span(self, data, **kwargs):
        """A tryout cannot end before it starts."""
        end = data.get('end_date')
        if end and data.get('date') and end < data['date']:
            raise ValidationError(
                _l('End date cannot be before start date.'), field_name='end_date'
            )


def score_field():
    """One evaluation criterion: 1 to 10, or not scored at all."""
    return fields.Integer(
        allow_none=True,
        load_default=None,
        validate=validate.Range(min=1, max=10, error=_l('Scores run from 1 to 10.')),
        error_messages={'invalid': _l('A score must be a whole number from 1 to 10.')},
    )


class EvaluationSchema(StripMixin):
    """A coach's assessment of one player in one tryout (ARCH-005).

    Each criterion is scored 1 to 10, or left blank. `validate_score` used to
    turn anything else — 11, 0, 'good' — into None: the criterion silently
    vanished from the average and the page reported the evaluation as
    submitted. A coach could score a player 11 out of 10 and have it counted
    as no score at all.

    The nine are spelled out rather than generated from Evaluation.CRITERIA,
    because a schema is worth reading. test_evaluations.py asserts that the
    two lists match, so adding a tenth criterion to the model and forgetting
    this file fails the suite rather than silently dropping the field.
    """

    mecanics_score = score_field()
    cohesion_score = score_field()
    communication_score = score_field()
    gamesense_score = score_field()
    versatility_score = score_field()
    discipline_score = score_field()
    analysis_score = score_field()
    sport_ethics_score = score_field()
    mental_score = score_field()

    comments = fields.String(
        validate=validate.Length(max=5000),
        allow_none=True,
        load_default=None,
    )
    position_recommendation = fields.String(
        validate=validate.Length(max=50),
        allow_none=True,
        load_default=None,
    )