from datetime import datetime

from flask import Blueprint, request, jsonify, g
from app import db
from app.models.user import User
from app.models.emergency_access import EmergencyAccess
from app.services.auth_service import require_jwt

emergency_bp = Blueprint('emergency', __name__)


@emergency_bp.route('', methods=['GET'])
@require_jwt
def list_emergency():
    """Return emergency access records both as grantor and as grantee."""
    user = User.query.get(g.current_user_id)

    grants = EmergencyAccess.query.filter_by(grantor_id=user.id).order_by(
        EmergencyAccess.created_at.desc()
    ).all()

    access = EmergencyAccess.query.filter(
        db.or_(
            EmergencyAccess.grantee_email == user.email,
            EmergencyAccess.grantee_id == user.id,
        )
    ).order_by(EmergencyAccess.created_at.desc()).all()

    return jsonify({
        'grants': [ea.to_dict(grantor_email=user.email) for ea in grants],
        'access': [_ea_as_grantee(ea) for ea in access],
    }), 200


def _ea_as_grantee(ea: EmergencyAccess) -> dict:
    grantor = User.query.get(ea.grantor_id)
    d = ea.to_dict(grantor_email=grantor.email if grantor else None)
    d['grantor_public_key'] = grantor.sharing_public_key if grantor else None
    return d


@emergency_bp.route('', methods=['POST'])
@require_jwt
def create_emergency():
    """Grantor creates an emergency access invitation for a trusted contact."""
    data = request.get_json(silent=True) or {}
    grantee_email = (data.get('grantee_email') or '').strip().lower()
    wait_days = int(data.get('wait_days', 7))

    if not grantee_email:
        return jsonify({'error': 'grantee_email is required'}), 400
    if not (1 <= wait_days <= 90):
        return jsonify({'error': 'wait_days must be between 1 and 90'}), 400

    owner = User.query.get(g.current_user_id)
    if owner.email == grantee_email:
        return jsonify({'error': 'Cannot designate yourself as emergency contact'}), 400

    # No duplicate active grants
    existing = EmergencyAccess.query.filter(
        EmergencyAccess.grantor_id == g.current_user_id,
        EmergencyAccess.grantee_email == grantee_email,
        EmergencyAccess.status != 'denied',
    ).first()
    if existing:
        return jsonify({'error': 'Emergency access already set up for this contact'}), 409

    grantee = User.query.filter_by(email=grantee_email).first()
    ea = EmergencyAccess(
        grantor_id=g.current_user_id,
        grantee_email=grantee_email,
        grantee_id=grantee.id if grantee else None,
        wait_days=wait_days,
    )
    db.session.add(ea)
    db.session.commit()

    return jsonify(ea.to_dict(grantor_email=owner.email)), 201


@emergency_bp.route('/<int:ea_id>', methods=['DELETE'])
@require_jwt
def delete_emergency(ea_id):
    """Grantor removes an emergency access grant."""
    ea = EmergencyAccess.query.filter_by(id=ea_id, grantor_id=g.current_user_id).first()
    if not ea:
        return jsonify({'error': 'Not found'}), 404
    db.session.delete(ea)
    db.session.commit()
    return jsonify({'message': 'Emergency access removed'}), 200


@emergency_bp.route('/<int:ea_id>/accept', methods=['POST'])
@require_jwt
def accept_emergency(ea_id):
    """Grantee accepts an emergency access invitation."""
    user = User.query.get(g.current_user_id)
    ea = EmergencyAccess.query.filter(
        EmergencyAccess.id == ea_id,
        EmergencyAccess.status == 'invited',
        db.or_(
            EmergencyAccess.grantee_email == user.email,
            EmergencyAccess.grantee_id == user.id,
        ),
    ).first()
    if not ea:
        return jsonify({'error': 'Not found or not in invited state'}), 404

    ea.status = 'accepted'
    ea.grantee_id = user.id
    db.session.commit()

    return jsonify(_ea_as_grantee(ea)), 200


@emergency_bp.route('/<int:ea_id>/provide', methods=['POST'])
@require_jwt
def provide_vault(ea_id):
    """
    Grantor provides the ECDH-encrypted vault snapshot for emergency recovery.

    The client re-encrypts each vault item's plaintext with the ECDH shared secret
    (grantor private key + grantee public key) and sends the JSON array as enc_vault.
    """
    ea = EmergencyAccess.query.filter_by(id=ea_id, grantor_id=g.current_user_id).first()
    if not ea:
        return jsonify({'error': 'Not found'}), 404
    if ea.status not in ('accepted', 'ready'):
        return jsonify({'error': 'Emergency access must be in accepted or ready state'}), 400

    data = request.get_json(silent=True) or {}
    enc_vault = data.get('enc_vault', '')
    if not enc_vault:
        return jsonify({'error': 'enc_vault (JSON array) is required'}), 400

    ea.enc_vault = enc_vault
    ea.status = 'ready'
    db.session.commit()

    grantor = User.query.get(g.current_user_id)
    return jsonify(ea.to_dict(grantor_email=grantor.email)), 200


@emergency_bp.route('/<int:ea_id>/request', methods=['POST'])
@require_jwt
def request_access(ea_id):
    """Grantee initiates an access request, starting the wait-period clock."""
    user = User.query.get(g.current_user_id)
    ea = EmergencyAccess.query.filter(
        EmergencyAccess.id == ea_id,
        EmergencyAccess.status == 'ready',
        db.or_(
            EmergencyAccess.grantee_email == user.email,
            EmergencyAccess.grantee_id == user.id,
        ),
    ).first()
    if not ea:
        return jsonify({'error': 'Not found or not in ready state'}), 404

    ea.status = 'pending'
    ea.request_initiated_at = datetime.utcnow()
    db.session.commit()

    return jsonify(_ea_as_grantee(ea)), 200


@emergency_bp.route('/<int:ea_id>/deny', methods=['POST'])
@require_jwt
def deny_access(ea_id):
    """Grantor denies a pending access request (resets to ready)."""
    ea = EmergencyAccess.query.filter_by(id=ea_id, grantor_id=g.current_user_id).first()
    if not ea:
        return jsonify({'error': 'Not found'}), 404
    if ea.status != 'pending':
        return jsonify({'error': 'No pending request to deny'}), 400

    ea.status = 'ready'
    ea.request_initiated_at = None
    db.session.commit()

    grantor = User.query.get(g.current_user_id)
    return jsonify(ea.to_dict(grantor_email=grantor.email)), 200


@emergency_bp.route('/<int:ea_id>/vault', methods=['GET'])
@require_jwt
def get_emergency_vault(ea_id):
    """
    Grantee retrieves the encrypted vault snapshot after the wait period has elapsed.
    Also returns the grantor's public key so the client can derive the ECDH secret.
    """
    user = User.query.get(g.current_user_id)
    ea = EmergencyAccess.query.filter(
        EmergencyAccess.id == ea_id,
        db.or_(
            EmergencyAccess.grantee_email == user.email,
            EmergencyAccess.grantee_id == user.id,
        ),
    ).first()
    if not ea:
        return jsonify({'error': 'Not found'}), 404
    if not ea.wait_elapsed:
        if ea.request_initiated_at:
            elapsed_secs = (datetime.utcnow() - ea.request_initiated_at).total_seconds()
            days_left = max(0, ea.wait_days - elapsed_secs / 86400)
        else:
            days_left = ea.wait_days
        return jsonify({
            'error': f'Wait period not yet elapsed ({days_left:.1f} day(s) remaining)'
        }), 403

    grantor = User.query.get(ea.grantor_id)
    return jsonify({
        'enc_vault': ea.enc_vault,
        'grantor_public_key': grantor.sharing_public_key if grantor else None,
    }), 200