import base64
import binascii
import logging
import re

from flask import Blueprint, request, jsonify, abort
from sqlalchemy import select

from app.extensions import db
from app.models.base import Group
from app.models.mirrors import Origin, Proxy

api = Blueprint('api', __name__)
logger = logging.getLogger(__name__)

MAX_DOMAIN_NAME_LENGTH = 255
DOMAIN_NAME_REGEX = re.compile(r'^[a-zA-Z0-9.\-]*$')
MAX_ALLOWED_ITEMS = 100


@api.errorhandler(400)
def bad_request(error):
    response = jsonify({'error': 'Bad Request', 'message': error.description})
    response.status_code = 400
    return response


@api.errorhandler(401)
def unauthorized(error):
    response = jsonify({'error': 'Unauthorized', 'message': error.description})
    response.status_code = 401
    return response


@api.errorhandler(404)
def not_found(error):
    response = jsonify({'error': 'Not found', 'message': 'Resource could not be found.'})
    response.status_code = 404
    return response


@api.errorhandler(500)
def internal_server_error(error):
    response = jsonify({'error': 'Internal Server Error', 'message': 'An unexpected error occurred.'})
    response.status_code = 500
    return response


@api.teardown_app_request
def shutdown_session(exception=None):
    db.session.remove()


def validate_max_items(max_items_str, max_allowed):
    try:
        max_items = int(max_items_str)
        if max_items <= 0 or max_items > max_allowed:
            raise ValueError()
        return max_items
    except ValueError:
        abort(400, description=f"MaxItems must be a positive integer not exceeding {max_allowed}.")


def validate_marker(marker_str):
    try:
        marker_decoded = base64.urlsafe_b64decode(marker_str.encode()).decode()
        marker_id = int(marker_decoded)
        return marker_id
    except (ValueError, binascii.Error):
        abort(400, description="Marker must be a valid token.")


def list_resources(
        model,
        filters=None,
        order_by=None,
        serialize_func=None,
        resource_name='ResourceList',
        max_items_param='MaxItems',
        marker_param='Marker',
        max_allowed_items=100
):
    try:
        marker = request.args.get(marker_param)
        max_items = validate_max_items(
            request.args.get(max_items_param, default='100'), max_allowed_items)
        query = select(model)

        if filters:
            query = query.where(*filters)

        if marker:
            marker_id = validate_marker(marker)
            query = query.where(model.id > marker_id)

        query = query.order_by(order_by or model.id)
        query = query.limit(max_items + 1)  # Need to know if there's more

        result = db.session.execute(query)
        items = result.scalars().all()
        items_list = [serialize_func(item) for item in items[:max_items]]
        is_truncated = len(items) > max_items

        response = {
            resource_name: {
                marker_param: marker if marker else None,
                max_items_param: str(max_items),
                "Quantity": len(items_list),
                "Items": items_list,
                "IsTruncated": is_truncated,
            }
        }

        if is_truncated:
            last_id = items[max_items - 1].id
            next_marker = base64.urlsafe_b64encode(str(last_id).encode()).decode()
            response[resource_name]["NextMarker"] = next_marker

        return jsonify(response)
    except Exception:
        logger.exception("An unexpected error occurred")
        abort(500)


@api.route('/web/group', methods=['GET'])
def list_groups():
    return list_resources(
        model=Group,
        serialize_func=lambda group: group.to_dict(),
        resource_name='OriginGroupList',
        max_allowed_items=MAX_ALLOWED_ITEMS
    )


@api.route('/web/origin', methods=['GET'])
def list_origins():
    domain_name_filter = request.args.get('DomainName')
    group_id_filter = request.args.get('GroupId')

    filters = []

    if domain_name_filter:
        if len(domain_name_filter) > MAX_DOMAIN_NAME_LENGTH:
            abort(400, description=f"DomainName cannot exceed {MAX_DOMAIN_NAME_LENGTH} characters.")
        if not DOMAIN_NAME_REGEX.match(domain_name_filter):
            abort(400, description="DomainName contains invalid characters.")
        filters.append(Origin.domain_name.ilike(f"%{domain_name_filter}%"))

    if group_id_filter:
        try:
            group_id_filter = int(group_id_filter)
            filters.append(Origin.group_id == group_id_filter)
        except ValueError:
            abort(400, description="GroupId must be a valid integer.")

    return list_resources(
        model=Origin,
        filters=filters,
        serialize_func=lambda origin: origin.to_dict(),
        resource_name='OriginsList',
        max_allowed_items=MAX_ALLOWED_ITEMS
    )


@api.route('/web/mirror', methods=['GET'])
def list_mirrors():
    status_filter = request.args.get('Status')

    filters = []

    if status_filter:
        if status_filter == "pending":
            filters.append(Proxy.url.is_(None))
            filters.append(Proxy.deprecated.is_(None))
            filters.append(Proxy.destroyed.is_(None))
        if status_filter == "active":
            filters.append(Proxy.url.is_not(None))
            filters.append(Proxy.deprecated.is_(None))
            filters.append(Proxy.destroyed.is_(None))
        if status_filter == "expiring":
            filters.append(Proxy.deprecated.is_not(None))
            filters.append(Proxy.destroyed.is_(None))
        if status_filter == "destroyed":
            filters.append(Proxy.destroyed.is_not(None))

    return list_resources(
        model=Proxy,
        filters=filters,
        serialize_func=lambda proxy: proxy.to_dict(),
        resource_name='MirrorsList',
        max_allowed_items=MAX_ALLOWED_ITEMS
    )