## Copyright © 2026 Olaf Kolkman
## SPDX-License-Identifier: GPL-3.0-or-later

from datetime import datetime, timedelta, timezone
import json
from uuid import uuid4

from fastapi import APIRouter, HTTPException
from pydantic import BaseModel

from backend.app.core.config import settings
from backend.app.database import get_connection, hash_password
from backend.app.services.email_service import get_smtp_settings, save_smtp_settings, send_test_email

router = APIRouter()


class SetupRequest(BaseModel):
    username: str
    email: str
    password: str
    smtp_host: str
    smtp_port: int = 587
    smtp_username: str = ''
    smtp_password: str = ''
    smtp_from: str
    smtp_use_tls: bool = True


class TestMailRequest(BaseModel):
    email: str | None = None


def has_administrator() -> bool:
    with get_connection() as conn:
        return conn.execute('SELECT 1 FROM users WHERE is_admin = 1 LIMIT 1').fetchone() is not None


def get_pending_setup() -> dict | None:
    with get_connection() as conn:
        row = conn.execute('SELECT value FROM app_settings WHERE name = ?', ('setup_pending',)).fetchone()
    return json.loads(row['value']) if row else None


def save_pending_setup(values: dict) -> None:
    with get_connection() as conn:
        conn.execute(
            '''INSERT INTO app_settings (name, value, updated_at) VALUES (?, ?, CURRENT_TIMESTAMP)
               ON CONFLICT(name) DO UPDATE SET value = excluded.value, updated_at = CURRENT_TIMESTAMP''',
            ('setup_pending', json.dumps(values)),
        )
        conn.execute('DELETE FROM app_settings WHERE name = ?', ('setup_mail_rate',))
        conn.commit()


def delete_pending_setup() -> None:
    with get_connection() as conn:
        conn.execute('DELETE FROM app_settings WHERE name = ?', ('setup_pending',))
        conn.execute('DELETE FROM app_settings WHERE name = ?', ('setup_mail_rate',))
        conn.commit()


@router.post('/configuration', status_code=200)
def save_configuration(payload: SetupRequest):
    if has_administrator():
        raise HTTPException(status_code=409, detail='LinkLog is already configured')
    username = payload.username.strip()
    email = payload.email.strip()
    smtp_host = payload.smtp_host.strip()
    smtp_from = payload.smtp_from.strip()
    if not username or not email or not smtp_host or not smtp_from or len(payload.password) < 8:
        raise HTTPException(status_code=422, detail='Admin credentials and SMTP settings are required')
    if not 1 <= payload.smtp_port <= 65535:
        raise HTTPException(status_code=422, detail='SMTP port must be between 1 and 65535')

    smtp_values = {
        'smtp_host': smtp_host,
        'smtp_port': payload.smtp_port,
        'smtp_username': payload.smtp_username.strip(),
        'smtp_password': payload.smtp_password,
        'smtp_from': smtp_from,
        'smtp_use_tls': payload.smtp_use_tls,
    }
    pending = {
        'username': username,
        'email': email,
        'password_hash': hash_password(payload.password),
    }
    save_pending_setup(pending)
    save_smtp_settings(smtp_values)
    return {'status': 'saved', 'message': 'Configuration saved. Send a test mail to verify SMTP delivery.'}


@router.post('/test-mail')
def test_mail(payload: TestMailRequest | None = None):
    if has_administrator():
        raise HTTPException(status_code=409, detail='LinkLog is already configured')
    pending = get_pending_setup()
    if pending is None:
        raise HTTPException(status_code=400, detail='Save the configuration before sending test mail')

    now = datetime.now(timezone.utc)
    with get_connection() as conn:
        row = conn.execute('SELECT value FROM app_settings WHERE name = ?', ('setup_mail_rate',)).fetchone()
        rate = json.loads(row['value']) if row else {}
    last_sent = datetime.fromisoformat(rate['last_sent']) if rate.get('last_sent') else None
    cooldown_until = datetime.fromisoformat(rate['cooldown_until']) if rate.get('cooldown_until') else None
    if cooldown_until and now >= cooldown_until:
        rate = {}
        last_sent = None
        cooldown_until = None
    if cooldown_until and now < cooldown_until:
        retry_after = int((cooldown_until - now).total_seconds()) + 1
        raise HTTPException(status_code=429, detail=f'Test mail limit reached. Try again in {retry_after} seconds.', headers={'Retry-After': str(retry_after)})
    if last_sent and now - last_sent < timedelta(seconds=20):
        retry_after = int((timedelta(seconds=20) - (now - last_sent)).total_seconds()) + 1
        raise HTTPException(status_code=429, detail=f'Please wait {retry_after} seconds before sending another test mail.', headers={'Retry-After': str(retry_after)})

    try:
        send_test_email(payload.email if payload and payload.email else pending['email'])
    except Exception as error:
        raise HTTPException(status_code=503, detail=f'SMTP test mail could not be sent: {error}') from error

    sends = int(rate.get('sends', 0)) + 1
    updated_rate = {'sends': sends, 'last_sent': now.isoformat()}
    if sends >= 5:
        updated_rate['cooldown_until'] = (now + timedelta(minutes=2)).isoformat()
    with get_connection() as conn:
        conn.execute(
            '''INSERT INTO app_settings (name, value, updated_at) VALUES (?, ?, CURRENT_TIMESTAMP)
               ON CONFLICT(name) DO UPDATE SET value = excluded.value, updated_at = CURRENT_TIMESTAMP''',
            ('setup_mail_rate', json.dumps(updated_rate)),
        )
        conn.commit()
    next_allowed = datetime.fromisoformat(updated_rate.get('cooldown_until')) if sends >= 5 else now + timedelta(seconds=20)
    return {
        'status': 'sent',
        'message': 'SMTP test mail sent.',
        'sends_remaining': max(0, 5 - sends),
        'cooldown_seconds': 120 if sends >= 5 else 0,
        'next_allowed_at': next_allowed.isoformat(),
    }


@router.post('/complete', status_code=201)
def complete_setup():
    if has_administrator():
        raise HTTPException(status_code=409, detail='LinkLog is already configured')
    pending = get_pending_setup()
    if pending is None:
        raise HTTPException(status_code=400, detail='Save the configuration before completing setup')
    with get_connection() as conn:
        row = conn.execute('SELECT value FROM app_settings WHERE name = ?', ('setup_mail_rate',)).fetchone()
    if row is None or int(json.loads(row['value']).get('sends', 0)) < 1:
        raise HTTPException(status_code=400, detail='Send a successful test mail before completing setup')
    user_id = str(uuid4())
    with get_connection() as conn:
        try:
            conn.execute(
                '''INSERT INTO users
                   (id, username, email, password_hash, is_admin, email_verified)
                   VALUES (?, ?, ?, ?, 1, 1)''',
                (user_id, pending['username'], pending['email'], pending['password_hash']),
            )
            conn.commit()
        except Exception as error:
            raise HTTPException(status_code=409, detail='Username or email already exists') from error
    delete_pending_setup()
    return {'status': 'configured', 'message': 'LinkLog is configured.'}


@router.get('/status')
def setup_status():
    rate = {}
    with get_connection() as conn:
        row = conn.execute('SELECT value FROM app_settings WHERE name = ?', ('setup_mail_rate',)).fetchone()
    if row:
        rate = json.loads(row['value'])
    now = datetime.now(timezone.utc)
    cooldown_until = datetime.fromisoformat(rate['cooldown_until']) if rate.get('cooldown_until') else None
    last_sent = datetime.fromisoformat(rate['last_sent']) if rate.get('last_sent') else None
    next_allowed = cooldown_until if cooldown_until and cooldown_until > now else (
        last_sent + timedelta(seconds=20) if last_sent else None
    )
    return {
        'configured': has_administrator(),
        'pending': get_pending_setup() is not None,
        'smtp_defaults': get_smtp_settings(),
        'sends_remaining': max(0, 5 - int(rate.get('sends', 0))),
        'next_allowed_at': next_allowed.isoformat() if next_allowed and next_allowed > now else None,
    }