import os
import re
import subprocess
import functools
from pathlib import Path

from flask import Flask, request, jsonify, send_file, Response

app = Flask(__name__)

VALID_NAME = re.compile(r'^[A-Za-z0-9_-]+$')
VALID_NFS_CLIENT = re.compile(r'^[A-Za-z0-9.*:/\-]+$')
ALLOWED_PATH_BASE = Path('/srv').resolve()

_AUTH_USER = os.environ.get('MICRONAS_USER', 'admin')
_AUTH_PASS = os.environ.get('MICRONAS_PASS', '')

if not _AUTH_PASS:
    import warnings
    warnings.warn(
        'MICRONAS_PASS is not set — all routes are unprotected! '
        'Set it via the environment or /etc/micronas.env.',
        stacklevel=1,
    )


def require_auth(f):
    @functools.wraps(f)
    def decorated(*args, **kwargs):
        if not _AUTH_PASS:
            return f(*args, **kwargs)
        auth = request.authorization
        if not auth or auth.username != _AUTH_USER or auth.password != _AUTH_PASS:
            return Response(
                'Unauthorized', 401,
                {'WWW-Authenticate': 'Basic realm="micronas"'},
            )
        return f(*args, **kwargs)
    return decorated


def validate_path(path_str):
    """Resolve path and ensure it falls under /srv."""
    try:
        p = Path(path_str).resolve()
    except Exception:
        raise ValueError('invalid path')
    allowed = str(ALLOWED_PATH_BASE)
    if not (str(p) == allowed or str(p).startswith(allowed + '/')):
        raise ValueError('path must be under /srv')
    return str(p)


# ===== SMB =====

_SMB_SKIP = {'global', 'homes', 'printers', 'print$', 'ipc$'}


def parse_smb():
    result = subprocess.run(['testparm', '-s'], capture_output=True, text=True)
    shares = []
    current = None

    for line in result.stdout.splitlines():
        line = line.rstrip()
        m = re.match(r'^\[(.+)\]$', line)
        if m:
            if current is not None and current['name'].lower() not in _SMB_SKIP:
                shares.append(current)
            current = {'name': m.group(1), 'path': '', 'valid_users': ''}
        elif current is not None and '=' in line:
            key, _, val = line.partition('=')
            key = key.strip().lower().replace(' ', '_')
            val = val.strip()
            if key == 'path':
                current['path'] = val
            elif key == 'valid_users':
                current['valid_users'] = val

    if current is not None and current['name'].lower() not in _SMB_SKIP:
        shares.append(current)

    return shares


def add_smb_share(name, path, valid_users):
    config = (
        f'\n[{name}]\n'
        f'   path = {path}\n'
        f'   valid users = {valid_users}\n'
        '   writable = yes\n'
        '   browseable = yes\n'
    )
    with open('/etc/samba/smb.conf', 'a') as f:
        f.write(config)
    subprocess.run(['smbcontrol', 'all', 'reload-config'], check=True)


# ===== NFS =====

def get_nfs_shares():
    shares = []
    try:
        with open('/etc/exports', 'r') as f:
            for line in f:
                line = line.strip()
                if not line or line.startswith('#'):
                    continue
                parts = line.split()
                shares.append({
                    'path': parts[0],
                    'clients': ' '.join(parts[1:]) if len(parts) > 1 else '*',
                })
    except FileNotFoundError:
        pass
    return shares


def add_nfs_share(path, clients, ro=False):
    options = 'ro' if ro else 'rw'
    export_line = f'{path}\t{clients}({options},sync,no_subtree_check)\n'
    with open('/etc/exports', 'a') as f:
        f.write(export_line)
    subprocess.run(['exportfs', '-ra'], check=True)


# ===== ROUTES =====

@app.route('/')
@require_auth
def index():
    return send_file(os.path.join(os.path.dirname(__file__), 'index.html'))


@app.route('/api/shares', methods=['GET'])
@require_auth
def get_all_shares():
    return jsonify({'smb': parse_smb(), 'nfs': get_nfs_shares()})


@app.route('/api/share/smb', methods=['POST'])
@require_auth
def create_smb():
    data = request.json or {}
    name = data.get('name', '')
    path = data.get('path', '')
    valid_users = data.get('validUsers', '')

    if not VALID_NAME.match(name):
        return jsonify({'error': 'invalid share name (letters, digits, _ -)'}), 400
    users = []
    for u in re.split(r'[\s,]+', valid_users):
        if not u:
            continue
        if not VALID_NAME.match(u):
            return jsonify({'error': f'invalid username: {u}'}), 400
        users.append(u)
    try:
        safe_path = validate_path(path)
    except ValueError as e:
        return jsonify({'error': str(e)}), 400

    add_smb_share(name, safe_path, ', '.join(users))
    return jsonify({'type': 'smb', 'status': 'created'})


@app.route('/api/share/nfs', methods=['POST'])
@require_auth
def create_nfs():
    data = request.json or {}
    path = data.get('path', '')
    clients = data.get('clients', '*')
    ro = data.get('readOnly', False)

    try:
        safe_path = validate_path(path)
    except ValueError as e:
        return jsonify({'error': str(e)}), 400
    if not VALID_NFS_CLIENT.match(clients):
        return jsonify({'error': 'invalid client spec'}), 400

    add_nfs_share(safe_path, clients, ro)
    return jsonify({'type': 'nfs', 'status': 'created'})


@app.route('/api/quota', methods=['POST'])
@require_auth
def set_quota():
    data = request.json or {}
    user = data.get('user', '')
    quota_type = data.get('type', 'smb')
    raw_quota = data.get('quota', 0)
    path = data.get('path', '/srv/samba')

    if not VALID_NAME.match(user):
        return jsonify({'error': 'invalid username'}), 400
    try:
        quota_gb = int(raw_quota)
        if quota_gb <= 0:
            raise ValueError()
    except (ValueError, TypeError):
        return jsonify({'error': 'quota must be a positive integer (GB)'}), 400

    if quota_type == 'smb':
        mount = '/srv/samba'
    else:
        try:
            mount = validate_path(path)
        except ValueError as e:
            return jsonify({'error': str(e)}), 400

    # setquota takes kilobytes; soft = requested, hard = +1 GB buffer
    soft_kb = str(quota_gb * 1024 * 1024)
    hard_kb = str((quota_gb + 1) * 1024 * 1024)
    subprocess.run(
        ['setquota', '-u', user, soft_kb, hard_kb, '0', '0', mount],
        check=True,
    )
    return jsonify({'status': 'ok'})


if __name__ == '__main__':
    app.run(host='0.0.0.0', port=5000, debug=False)