import asyncio
import logging
from datetime import datetime
from pathlib import Path

from pydantic import ValidationError

from fastapi import Depends, FastAPI, Form, HTTPException, Request, Response, status
from fastapi.middleware.trustedhost import TrustedHostMiddleware
from fastapi.responses import HTMLResponse, JSONResponse, RedirectResponse
from fastapi.staticfiles import StaticFiles
from fastapi.templating import Jinja2Templates
from sqlalchemy import inspect, text
from sqlalchemy.orm import Session

from app.core.config import settings
from app.core.cookies import cookie_secure
from app.core.security import create_access_token, hash_password, verify_password
from app.db.session import Base, engine, get_db
from app.models.system import SendLog
from app.models.user import User
from app.schemas.user import PasswordChange, ProfileUpdate, UserCreate
from app.services.auth import get_admin_user, get_current_user, get_optional_user, require_editor_or_admin
from app.services.config_store import get_config, set_config
from app.services.csrf import CSRF_COOKIE_NAME, ensure_csrf_cookie, generate_csrf_token, validate_csrf
from app.services.newsletter import (
    DEFAULT_DISPLAY,
    article_url,
    create_html,
    create_outlook_html,
    create_plain_text,
    create_subject,
    filter_articles,
    parse_display_options,
    parse_highlights,
    resolve_period,
    split_articles_by_type,
)
from app.services.smtp_sender import get_smtp_settings, mark_scheduled_sent, schedule_is_due, send_newsletter
from app.services.wiki import WikiFetchError, WikiService

app = FastAPI(title=settings.app_name)
allowed_hosts = [h.strip() for h in settings.allowed_hosts.split(",") if h.strip()]
if allowed_hosts:
    app.add_middleware(TrustedHostMiddleware, allowed_hosts=allowed_hosts)
app.mount("/static", StaticFiles(directory="app/static"), name="static")
templates = Jinja2Templates(directory="app/templates")
templates.env.globals["wiki_article_url"] = article_url
wiki_service = WikiService()

logger = logging.getLogger("newsletter.scheduler")
SCHEDULER_INTERVAL_SECONDS = 60
_scheduler_task: asyncio.Task | None = None


@app.on_event("startup")
def on_startup() -> None:
    Path("data").mkdir(parents=True, exist_ok=True)
    Base.metadata.create_all(bind=engine)
    _ensure_schema_upgrades()
    _bootstrap_admin()
    global _scheduler_task
    _scheduler_task = asyncio.create_task(_scheduler_loop())


@app.on_event("shutdown")
async def on_shutdown() -> None:
    if _scheduler_task is not None:
        _scheduler_task.cancel()


async def _scheduler_loop() -> None:
    """Prüft periodisch, ob laut Zeitplan ein Newsletter-Versand fällig ist."""
    while True:
        try:
            await asyncio.sleep(SCHEDULER_INTERVAL_SECONDS)
            await _run_scheduled_send_if_due()
        except asyncio.CancelledError:
            break
        except Exception:
            logger.exception("Fehler im Scheduler-Loop")


async def _run_scheduled_send_if_due() -> None:
    db = next(get_db())
    try:
        settings_snapshot = get_smtp_settings(db)
        now = datetime.now()
        if not schedule_is_due(settings_snapshot, now):
            return

        try:
            days = int(settings_snapshot.get("gen_days") or "30")
        except ValueError:
            days = 30
        gen = await _generate_newsletter(
            period_mode=settings_snapshot.get("gen_period", "days"),
            days=max(1, min(days, 90)),
            article_type=settings_snapshot.get("gen_article_type", "all"),
            category=settings_snapshot.get("gen_category", ""),
            display=DEFAULT_DISPLAY,
            editor_tip="",
            highlight_list=[],
        )
        if gen["wiki_error"] or not gen["articles"]:
            # Kein Versand ohne Inhalt; erneuter Versuch beim nächsten Intervall.
            logger.info("Geplanter Versand übersprungen (kein Inhalt/Wiki-Fehler).")
            return

        recipients = [r.strip() for r in settings_snapshot.get("recipients", "").split(",") if r.strip()]
        send_newsletter(db, gen["subject"], gen["raw_html"], gen["plain_text"], recipients, scheduled=True)
        mark_scheduled_sent(db, now)
    finally:
        db.close()


def _ensure_schema_upgrades() -> None:
    inspector = inspect(engine)
    with engine.begin() as conn:
        if "users" in inspector.get_table_names():
            cols = {c["name"] for c in inspector.get_columns("users")}
            if "role" not in cols:
                conn.execute(text("ALTER TABLE users ADD COLUMN role VARCHAR(32) NOT NULL DEFAULT 'reader'"))
                conn.execute(text("UPDATE users SET role = CASE WHEN is_admin = 1 THEN 'admin' ELSE 'reader' END"))


@app.middleware("http")
async def add_security_headers(request: Request, call_next):
    cookie_token = request.cookies.get(CSRF_COOKIE_NAME)
    request.state.csrf_token = cookie_token or generate_csrf_token()

    response: Response = await call_next(request)
    response.headers["X-Content-Type-Options"] = "nosniff"
    response.headers["X-Frame-Options"] = "DENY"
    response.headers["Referrer-Policy"] = "same-origin"
    # Die Newsletter-Vorschau läuft in einem srcdoc-iframe und erbt diese CSP.
    # E-Mail-HTML benötigt zwingend Inline-Styles; das Logo liegt auf einem externen https-Host.
    response.headers["Content-Security-Policy"] = (
        "default-src 'self'; "
        "img-src 'self' https: data:; "
        "style-src 'self' 'unsafe-inline'; "
        "script-src 'self';"
    )
    if not cookie_token:
        response.set_cookie(
            CSRF_COOKIE_NAME,
            request.state.csrf_token,
            httponly=True,
            secure=cookie_secure(request),
            samesite="strict",
        )
    return response


def _bootstrap_admin() -> None:
    db = next(get_db())
    try:
        existing = db.query(User).filter(User.email == settings.admin_bootstrap_email).first()
        if existing:
            if settings.admin_bootstrap_reset:
                existing.password_hash = hash_password(settings.admin_bootstrap_password)
                existing.is_admin = True
                existing.role = "admin"
                existing.is_active = True
                db.commit()
            return
        user = User(
            email=settings.admin_bootstrap_email,
            full_name="Initial Admin",
            password_hash=hash_password(settings.admin_bootstrap_password),
            is_admin=True,
            role="admin",
            is_active=True,
        )
        db.add(user)
        db.commit()
    finally:
        db.close()


def _base_context(request: Request, user: User, db: Session) -> dict:
    path = request.url.path
    active_nav = "dashboard"
    if path.startswith("/admin/users"):
        active_nav = "users"
    elif path.startswith("/profil"):
        active_nav = "profile"
    return {
        "user": user,
        "csrf_token": ensure_csrf_cookie(request),
        "smtp": get_smtp_settings(db),
        "active_nav": active_nav,
    }


def _render(request: Request, name: str, context: dict) -> HTMLResponse:
    return templates.TemplateResponse(request=request, name=name, context=context)


def _wants_html(request: Request) -> bool:
    accept = request.headers.get("accept", "")
    return "text/html" in accept or "*/*" in accept or accept == ""


@app.exception_handler(HTTPException)
async def http_exception_handler(request: Request, exc: HTTPException):
    if exc.status_code == status.HTTP_401_UNAUTHORIZED and _wants_html(request):
        return RedirectResponse(url="/login", status_code=status.HTTP_302_FOUND)
    if exc.status_code == status.HTTP_403_FORBIDDEN and _wants_html(request):
        return RedirectResponse(url="/dashboard", status_code=status.HTTP_302_FOUND)
    return JSONResponse(status_code=exc.status_code, content={"detail": exc.detail})


@app.get("/", response_class=HTMLResponse)
def index(request: Request, db: Session = Depends(get_db)):
    user = get_optional_user(request, db)
    target = "/dashboard" if user else "/login"
    return RedirectResponse(url=target, status_code=status.HTTP_302_FOUND)


@app.get("/login", response_class=HTMLResponse)
def login_page(request: Request, db: Session = Depends(get_db)):
    if get_optional_user(request, db):
        return RedirectResponse(url="/dashboard", status_code=status.HTTP_302_FOUND)
    return _render(
        request,
        "login.html",
        {
            "csrf_token": ensure_csrf_cookie(request),
            "error_message": None,
        },
    )


@app.post("/login")
def login(
    request: Request,
    csrf_token: str = Form(...),
    email: str = Form(...),
    password: str = Form(...),
    db: Session = Depends(get_db),
):
    try:
        validate_csrf(request, csrf_token)
    except HTTPException:
        return _render(
            request,
            "login.html",
            {
                "csrf_token": ensure_csrf_cookie(request),
                "error_message": "Sitzung abgelaufen. Bitte erneut anmelden.",
            },
        )
    user = db.query(User).filter(User.email == email, User.is_active.is_(True)).first()
    if not user or not verify_password(password, user.password_hash):
        return _render(
            request,
            "login.html",
            {
                "csrf_token": ensure_csrf_cookie(request),
                "error_message": "Ungültige Zugangsdaten.",
            },
        )
    token = create_access_token(user.id)
    response = RedirectResponse(url="/dashboard", status_code=status.HTTP_302_FOUND)
    response.set_cookie("access_token", token, httponly=True, secure=cookie_secure(request), samesite="strict")
    return response


@app.post("/logout")
def logout(request: Request, csrf_token: str = Form(...)):
    validate_csrf(request, csrf_token)
    response = RedirectResponse(url="/login", status_code=status.HTTP_302_FOUND)
    response.delete_cookie("access_token")
    return response


def _empty_filters() -> dict:
    return {
        "days": 30,
        "period": "last_month",
        "article_type": "new",
        "category": "",
        "display": DEFAULT_DISPLAY,
        "editor_tip": "",
        "highlights": "",
    }


async def _generate_newsletter(
    *,
    period_mode: str,
    days: int,
    article_type: str,
    category: str,
    display,
    editor_tip: str,
    highlight_list: list[str],
) -> dict:
    p = resolve_period(period_mode, days)
    result = {
        "period": p,
        "wiki_error": None,
        "articles": [],
        "articles_new": [],
        "articles_edited": [],
        "plain_text": "",
        "raw_html": "",
        "outlook_html": "",
        "subject": "",
    }
    try:
        articles = await wiki_service.get_recent_changes(
            days=p["days"], article_type=article_type, start=p["start"], end=p["end"]
        )
        filtered = filter_articles(articles, category_filter=category or None)
        new_articles, edited_articles = split_articles_by_type(filtered)
        prange = (p["start_str"], p["end_str"])
        result.update(
            {
                "articles": filtered,
                "articles_new": new_articles,
                "articles_edited": edited_articles,
                "subject": create_subject(p["month_label"], p["days"]),
                "plain_text": create_plain_text(filtered, p["days"], display, category, editor_tip, highlight_list, p["label"], prange, article_type),
                "raw_html": create_html(filtered, p["days"], display, category, editor_tip, highlight_list, p["label"], prange, article_type, p["month_label"]),
                "outlook_html": create_outlook_html(filtered, p["days"], display, category, editor_tip, highlight_list, p["label"], prange, article_type, p["month_label"]),
            }
        )
    except WikiFetchError as exc:
        result["wiki_error"] = exc.message
    return result


@app.get("/dashboard", response_class=HTMLResponse)
async def dashboard(request: Request, db: Session = Depends(get_db), current_user: User = Depends(get_current_user)):
    context = _base_context(request, current_user, db)
    context.update({
        "articles": [],
        "articles_new": [],
        "articles_edited": [],
        "raw_html": "",
        "outlook_html": "",
        "plain_text": "",
        "subject": "",
        "filters": _empty_filters(),
        "wiki_error": None,
        "send_result": None,
    })
    logs = db.query(SendLog).order_by(SendLog.created_at.desc()).limit(20).all()
    context["send_logs"] = logs
    return _render(request, "dashboard.html", context)


@app.post("/dashboard", response_class=HTMLResponse)
async def dashboard_generate(
    request: Request,
    csrf_token: str = Form(...),
    period: str = Form("days"),
    days: int = Form(30),
    article_type: str = Form("all"),
    category: str = Form(""),
    show_date: str | None = Form(None),
    show_user: str | None = Form(None),
    show_category: str | None = Form(None),
    editor_tip: str = Form(""),
    highlights: str = Form(""),
    db: Session = Depends(get_db),
    current_user: User = Depends(require_editor_or_admin),
):
    validate_csrf(request, csrf_token)
    days = max(1, min(days, 90))
    if article_type not in ("all", "new", "edited"):
        article_type = "all"
    display = parse_display_options(show_date, show_user, show_category)
    highlight_list = parse_highlights(highlights)

    gen = await _generate_newsletter(
        period_mode=period,
        days=days,
        article_type=article_type,
        category=category,
        display=display,
        editor_tip=editor_tip,
        highlight_list=highlight_list,
    )

    context = _base_context(request, current_user, db)
    context.update(
        {
            "articles": gen["articles"],
            "articles_new": gen["articles_new"],
            "articles_edited": gen["articles_edited"],
            "raw_html": gen["raw_html"],
            "outlook_html": gen["outlook_html"],
            "plain_text": gen["plain_text"],
            "subject": gen["subject"],
            "filters": {
                "days": days,
                "period": period,
                "article_type": article_type,
                "category": category,
                "display": display,
                "editor_tip": editor_tip,
                "highlights": highlights,
            },
            "send_logs": db.query(SendLog).order_by(SendLog.created_at.desc()).limit(20).all(),
            "wiki_error": gen["wiki_error"],
            "send_result": None,
        }
    )
    return _render(request, "dashboard.html", context)


@app.post("/newsletter/send-now", response_class=HTMLResponse)
async def send_now(
    request: Request,
    csrf_token: str = Form(...),
    period: str = Form("days"),
    days: int = Form(30),
    article_type: str = Form("all"),
    category: str = Form(""),
    show_date: str | None = Form(None),
    show_user: str | None = Form(None),
    show_category: str | None = Form(None),
    editor_tip: str = Form(""),
    highlights: str = Form(""),
    db: Session = Depends(get_db),
    current_user: User = Depends(require_editor_or_admin),
):
    validate_csrf(request, csrf_token)
    display = parse_display_options(show_date, show_user, show_category)
    if article_type not in ("all", "new", "edited"):
        article_type = "all"
    highlight_list = parse_highlights(highlights)
    days = max(1, min(days, 90))

    gen = await _generate_newsletter(
        period_mode=period,
        days=days,
        article_type=article_type,
        category=category,
        display=display,
        editor_tip=editor_tip,
        highlight_list=highlight_list,
    )

    send_result: dict[str, str]
    if gen["wiki_error"]:
        send_result = {"status": "failed", "message": f"Versand abgebrochen – Wiki-Fehler: {gen['wiki_error']}"}
    elif not gen["articles"]:
        send_result = {"status": "failed", "message": "Versand abgebrochen – im Zeitraum wurden keine Artikel gefunden."}
    else:
        recipients = [r.strip() for r in get_config(db, "smtp.recipients", "").split(",") if r.strip()]
        status_code, detail = send_newsletter(db, gen["subject"], gen["raw_html"], gen["plain_text"], recipients, scheduled=False)
        send_result = {"status": status_code, "message": detail}

    context = _base_context(request, current_user, db)
    context.update(
        {
            "articles": gen["articles"],
            "articles_new": gen["articles_new"],
            "articles_edited": gen["articles_edited"],
            "raw_html": gen["raw_html"],
            "outlook_html": gen["outlook_html"],
            "plain_text": gen["plain_text"],
            "subject": gen["subject"],
            "filters": {
                "days": days,
                "period": period,
                "article_type": article_type,
                "category": category,
                "display": display,
                "editor_tip": editor_tip,
                "highlights": highlights,
            },
            "send_logs": db.query(SendLog).order_by(SendLog.created_at.desc()).limit(20).all(),
            "wiki_error": gen["wiki_error"],
            "send_result": send_result,
        }
    )
    return _render(request, "dashboard.html", context)


@app.post("/admin/smtp")
def update_smtp_settings(
    request: Request,
    csrf_token: str = Form(...),
    enabled: str | None = Form(None),
    host: str = Form(""),
    port: str = Form("587"),
    username: str = Form(""),
    password: str = Form(""),
    from_email: str = Form(""),
    use_tls: str | None = Form(None),
    recipients: str = Form(""),
    schedule_enabled: str | None = Form(None),
    schedule_frequency: str = Form("monthly"),
    schedule_time: str = Form("08:00"),
    schedule_weekdays: list[str] = Form(default=[]),
    schedule_dom: str = Form("1"),
    gen_period: str = Form("days"),
    gen_days: str = Form("30"),
    gen_article_type: str = Form("all"),
    gen_category: str = Form(""),
    db: Session = Depends(get_db),
    admin: User = Depends(get_admin_user),
):
    validate_csrf(request, csrf_token)
    set_config(db, "smtp.enabled", "true" if enabled == "true" else "false")
    set_config(db, "smtp.host", host.strip())
    set_config(db, "smtp.port", port.strip() or "587")
    set_config(db, "smtp.username", username.strip())
    set_config(db, "smtp.password", password)
    set_config(db, "smtp.from_email", from_email.strip())
    set_config(db, "smtp.use_tls", "true" if use_tls == "true" else "false")
    set_config(db, "smtp.recipients", recipients.strip())

    set_config(db, "smtp.schedule_enabled", "true" if schedule_enabled == "true" else "false")
    if schedule_frequency not in ("daily", "weekly", "monthly"):
        schedule_frequency = "monthly"
    set_config(db, "smtp.schedule_frequency", schedule_frequency)
    set_config(db, "smtp.schedule_time", schedule_time.strip() or "08:00")
    valid_weekdays = [d for d in schedule_weekdays if d in {"0", "1", "2", "3", "4", "5", "6"}]
    set_config(db, "smtp.schedule_weekdays", ",".join(valid_weekdays))
    try:
        dom = max(1, min(int(schedule_dom), 28))
    except ValueError:
        dom = 1
    set_config(db, "smtp.schedule_dom", str(dom))

    if gen_period not in ("days", "last_month"):
        gen_period = "days"
    set_config(db, "smtp.gen_period", gen_period)
    try:
        gdays = max(1, min(int(gen_days), 90))
    except ValueError:
        gdays = 30
    set_config(db, "smtp.gen_days", str(gdays))
    if gen_article_type not in ("all", "new", "edited"):
        gen_article_type = "all"
    set_config(db, "smtp.gen_article_type", gen_article_type)
    set_config(db, "smtp.gen_category", gen_category.strip())
    return RedirectResponse(url="/dashboard", status_code=status.HTTP_302_FOUND)


def _users_context(request: Request, admin: User, db: Session, **extra) -> dict:
    context = _base_context(request, admin, db)
    context["users"] = db.query(User).order_by(User.created_at.desc()).all()
    context.setdefault("error_message", None)
    context.setdefault("success_message", None)
    context.update(extra)
    return context


def _format_validation_error(exc: ValidationError) -> str:
    messages: list[str] = []
    for err in exc.errors():
        msg = err.get("msg", "Ungültige Eingabe")
        if msg.startswith("Value error, "):
            msg = msg[13:]
        messages.append(msg)
    return " ".join(messages) if messages else "Ungültige Eingabe."


@app.get("/admin/users", response_class=HTMLResponse)
def users_page(request: Request, db: Session = Depends(get_db), admin: User = Depends(get_admin_user)):
    created = request.query_params.get("created") == "1"
    return _render(
        request,
        "users.html",
        _users_context(
            request,
            admin,
            db,
            success_message="Benutzer wurde erfolgreich angelegt." if created else None,
        ),
    )


@app.post("/admin/users", response_class=HTMLResponse)
def create_user(
    request: Request,
    csrf_token: str = Form(...),
    email: str = Form(...),
    full_name: str = Form(...),
    password: str = Form(...),
    role: str = Form("reader"),
    db: Session = Depends(get_db),
    admin: User = Depends(get_admin_user),
):
    try:
        validate_csrf(request, csrf_token)
    except HTTPException:
        return _render(
            request,
            "users.html",
            _users_context(request, admin, db, error_message="Sitzung abgelaufen. Bitte Seite neu laden und erneut versuchen."),
        )

    try:
        payload = UserCreate(email=email.strip(), full_name=full_name.strip(), password=password, role=role)
    except ValidationError as exc:
        return _render(
            request,
            "users.html",
            _users_context(request, admin, db, error_message=_format_validation_error(exc)),
        )

    existing = db.query(User).filter(User.email == payload.email).first()
    if existing:
        return _render(
            request,
            "users.html",
            _users_context(request, admin, db, error_message="Diese E-Mail-Adresse ist bereits registriert."),
        )

    user = User(
        email=payload.email,
        full_name=payload.full_name,
        password_hash=hash_password(payload.password),
        is_admin=payload.role == "admin",
        role=payload.role,
        is_active=True,
    )
    db.add(user)
    db.commit()
    return RedirectResponse(url="/admin/users?created=1", status_code=status.HTTP_302_FOUND)


def _profile_context(request: Request, user: User, db: Session, **extra) -> dict:
    context = _base_context(request, user, db)
    context.setdefault("error_message", None)
    context.setdefault("pw_error_message", None)
    context.setdefault("success_message", None)
    context.update(extra)
    return context


@app.get("/profil", response_class=HTMLResponse)
def profile_page(request: Request, db: Session = Depends(get_db), current_user: User = Depends(get_current_user)):
    success = None
    if request.query_params.get("updated") == "1":
        success = "Profil wurde aktualisiert."
    elif request.query_params.get("pw") == "1":
        success = "Passwort wurde geändert."
    return _render(request, "profile.html", _profile_context(request, current_user, db, success_message=success))


@app.post("/profil", response_class=HTMLResponse)
def update_profile(
    request: Request,
    csrf_token: str = Form(...),
    email: str = Form(...),
    full_name: str = Form(...),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    try:
        validate_csrf(request, csrf_token)
    except HTTPException:
        return _render(
            request,
            "profile.html",
            _profile_context(request, current_user, db, error_message="Sitzung abgelaufen. Bitte Seite neu laden und erneut versuchen."),
        )

    try:
        payload = ProfileUpdate(email=email.strip(), full_name=full_name.strip())
    except ValidationError as exc:
        return _render(
            request,
            "profile.html",
            _profile_context(request, current_user, db, error_message=_format_validation_error(exc)),
        )

    clash = db.query(User).filter(User.email == payload.email, User.id != current_user.id).first()
    if clash:
        return _render(
            request,
            "profile.html",
            _profile_context(request, current_user, db, error_message="Diese E-Mail-Adresse wird bereits verwendet."),
        )

    current_user.email = payload.email
    current_user.full_name = payload.full_name
    db.commit()
    return RedirectResponse(url="/profil?updated=1", status_code=status.HTTP_302_FOUND)


@app.post("/profil/passwort", response_class=HTMLResponse)
def change_password(
    request: Request,
    csrf_token: str = Form(...),
    current_password: str = Form(...),
    new_password: str = Form(...),
    confirm_password: str = Form(...),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    try:
        validate_csrf(request, csrf_token)
    except HTTPException:
        return _render(
            request,
            "profile.html",
            _profile_context(request, current_user, db, pw_error_message="Sitzung abgelaufen. Bitte Seite neu laden und erneut versuchen."),
        )

    if not verify_password(current_password, current_user.password_hash):
        return _render(
            request,
            "profile.html",
            _profile_context(request, current_user, db, pw_error_message="Das aktuelle Passwort ist nicht korrekt."),
        )

    if new_password != confirm_password:
        return _render(
            request,
            "profile.html",
            _profile_context(request, current_user, db, pw_error_message="Die neuen Passwörter stimmen nicht überein."),
        )

    try:
        payload = PasswordChange(new_password=new_password)
    except ValidationError as exc:
        return _render(
            request,
            "profile.html",
            _profile_context(request, current_user, db, pw_error_message=_format_validation_error(exc)),
        )

    current_user.password_hash = hash_password(payload.new_password)
    db.commit()
    return RedirectResponse(url="/profil?pw=1", status_code=status.HTTP_302_FOUND)