import os
from datetime import datetime, timedelta, timezone
from zoneinfo import ZoneInfo, ZoneInfoNotFoundError

import click
from flask import Flask, jsonify, redirect, render_template, request, url_for
from flask_login import (
    LoginManager,
    current_user,
    login_required,
    login_user,
    logout_user,
)

from models import Sensor, SensorReadout, User, db

login_manager = LoginManager()


def create_app():
    app = Flask(__name__)

    db_path = os.path.join(os.path.dirname(__file__), "data.db")
    app.config["SQLALCHEMY_DATABASE_URI"] = f"sqlite:///{db_path}"
    app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
    app.config["SECRET_KEY"] = os.environ.get("SECRET_KEY", "dev-secret-key-change-me")

    db.init_app(app)
    login_manager.init_app(app)
    login_manager.login_view = "login"

    @login_manager.user_loader
    def load_user(user_id):
        return db.session.get(User, int(user_id))

    @login_manager.unauthorized_handler
    def unauthorized():
        # Return JSON for API calls instead of redirecting to the login page.
        if request.path.startswith("/api/"):
            return jsonify({"error": "authentication required"}), 401
        next_page = request.path
        login_url = url_for("login")
        if next_page and next_page != login_url:
            login_url += f"?next={next_page}"
        return redirect(login_url)

    def _is_safe_next(target: str | None) -> bool:
        return bool(target) and target.startswith("/") and not target.startswith("//")

    # --- Pages ---

    @app.route("/")
    def index():
        if current_user.is_authenticated:
            return redirect(url_for("home"))
        return redirect(url_for("login"))

    @app.route("/login", methods=["GET", "POST"])
    def login():
        if current_user.is_authenticated:
            return redirect(url_for("home"))
        error = None
        if request.method == "POST":
            username = request.form.get("username", "").strip()
            password = request.form.get("password", "")
            user = User.query.filter_by(username=username).first()
            if user and user.check_password(password):
                login_user(user)
                next_page = request.args.get("next") or request.form.get("next")
                if not _is_safe_next(next_page):
                    next_page = url_for("home")
                return redirect(next_page)
            error = "Invalid username or password."
        return render_template("login.html", error=error, next=request.args.get("next", ""))

    @app.route("/logout")
    @login_required
    def logout():
        logout_user()
        return redirect(url_for("login"))

    @app.route("/home")
    @login_required
    def home():
        return render_template("home.html", user=current_user)

    @app.route("/sensors")
    @login_required
    def sensors_page():
        return render_template("sensors.html", user=current_user)

    @app.route("/api/docs")
    @login_required
    def api_docs():
        return render_template("docs.html", user=current_user)

    # --- API: device endpoints (intentionally public) ---
    # The sensor firmware has no browser session, but it needs the sensor
    # list to resolve a name to an id before pushing readouts.

    @app.route("/api/sensors")
    def api_sensors():
        sensors = Sensor.query.order_by(Sensor.name).all()
        return jsonify([{"id": s.id, "name": s.name} for s in sensors])

    # --- API: dashboard reads (login required, the browser session cookie is enough) ---

    @app.route("/api/sensors/<int:sensor_id>/types")
    @login_required
    def api_sensor_types(sensor_id):
        types = (
            db.session.query(SensorReadout.type)
            .filter_by(sensor_id=sensor_id)
            .distinct()
            .order_by(SensorReadout.type)
            .all()
        )
        return jsonify([t[0] for t in types])

    @app.route("/api/sensors/<int:sensor_id>/readouts")
    @login_required
    def api_sensor_readouts(sensor_id):
        type_ = request.args.get("type")
        query = SensorReadout.query.filter_by(sensor_id=sensor_id)
        if type_:
            query = query.filter_by(type=type_)
        readouts = query.order_by(SensorReadout.timestamp.desc()).limit(300).all()
        return jsonify(
            [
                {"value": r.value, "timestamp": r.timestamp.isoformat() + "Z"}
                for r in readouts
            ]
        )

    @app.route("/api/sensors/<int:sensor_id>/readouts/hourly")
    @login_required
    def api_sensor_readouts_hourly(sensor_id):
        type_ = request.args.get("type")
        range_ = request.args.get("range", "all")
        # Frontend wysyła strefę czasową przeglądarki (np. Europe/Warsaw),
        # żeby "today" znaczyło "od północy czasu lokalnego", a nie UTC.
        tz_name = request.args.get("tz", "Europe/Warsaw") or "Europe/Warsaw"
        try:
            local_tz = ZoneInfo(tz_name)
        except (ZoneInfoNotFoundError, ValueError):
            return jsonify({"error": f"unknown timezone: {tz_name}"}), 400
        # Timestamps are stored as naive UTC, so the cutoff must be naive UTC too.
        now_utc = datetime.now(timezone.utc)
        now_local = now_utc.astimezone(local_tz)
        if range_ == "today":
            midnight_local = now_local.replace(hour=0, minute=0, second=0, microsecond=0)
            cutoff = midnight_local.astimezone(timezone.utc).replace(tzinfo=None)
        elif range_ == "24h":
            cutoff = (now_utc - timedelta(hours=24)).replace(tzinfo=None)
        elif range_ == "week":
            cutoff = (now_utc - timedelta(days=7)).replace(tzinfo=None)
        elif range_ == "month":
            cutoff = (now_utc - timedelta(days=30)).replace(tzinfo=None)
        elif range_ == "all":
            cutoff = None
        else:
            return jsonify({"error": "range must be one of: today, 24h, week, month, all"}), 400
        query = db.session.query(SensorReadout.timestamp, SensorReadout.value).filter(
            SensorReadout.sensor_id == sensor_id
        )
        if cutoff is not None:
            query = query.filter(SensorReadout.timestamp >= cutoff)
        if type_:
            query = query.filter(SensorReadout.type == type_)
        rows = query.order_by(SensorReadout.timestamp).all()
        # Zakresy today i 24h domyślnie zwracają wszystkie pomiary bez
        # uśredniania; checkbox "hourly average" wymusza średnie godzinowe.
        averaged = range_ not in ("today", "24h") or request.args.get(
            "avg", "0"
        ).lower() in ("1", "true", "yes")
        if not averaged:
            return jsonify(
                [
                    {
                        "timestamp": ts.strftime("%Y-%m-%dT%H:%M:%S"),
                        "value": value,
                    }
                    for ts, value in rows
                ]
            )
        # Pozostałe zakresy: średnia godzinowa liczona po pełnej godzinie
        # lokalnej (poprawne też przy zmianie DST), znacznik to początek
        # godziny w UTC (frontend dokleja "Z").
        buckets: dict[datetime, list[float]] = {}
        for ts, value in rows:
            ts_utc = ts.replace(tzinfo=timezone.utc)
            hour_local = ts_utc.astimezone(local_tz).replace(
                minute=0, second=0, microsecond=0
            )
            hour_utc = hour_local.astimezone(timezone.utc).replace(tzinfo=None)
            buckets.setdefault(hour_utc, []).append(value)
        result = [
            {
                "timestamp": hour.strftime("%Y-%m-%dT%H:00:00"),
                "value": round(sum(values) / len(values), 2),
            }
            for hour, values in sorted(buckets.items())
        ]
        return jsonify(result)

    # --- API: device writes (intentionally public — called by devices/sensors) ---

    @app.route("/api/sensors", methods=["POST"])
    def api_create_sensor():
        data = request.get_json(silent=True)
        if not data or "name" not in data:
            return jsonify({"error": "name is required"}), 400

        name = data["name"].strip()
        if not name:
            return jsonify({"error": "name cannot be empty"}), 400

        if Sensor.query.filter_by(name=name).first():
            return jsonify({"error": "sensor already exists"}), 409

        sensor = Sensor(name=name)
        db.session.add(sensor)
        db.session.commit()
        return jsonify({"id": sensor.id, "name": sensor.name}), 201

    @app.route("/api/sensors/<int:sensor_id>/readouts", methods=["POST"])
    def api_create_readout(sensor_id):
        sensor = db.session.get(Sensor, sensor_id)
        if not sensor:
            return jsonify({"error": "sensor not found"}), 404

        data = request.get_json(silent=True)
        if not data:
            return jsonify({"error": "request body is required"}), 400

        missing = [f for f in ("type", "value") if f not in data]
        if missing:
            return jsonify({"error": f"missing fields: {', '.join(missing)}"}), 400

        try:
            value = float(data["value"])
        except (TypeError, ValueError):
            return jsonify({"error": "value must be a number"}), 400

        readout = SensorReadout(
            sensor_id=sensor_id,
            type=str(data["type"]).strip(),
            value=value,
        )
        db.session.add(readout)
        db.session.commit()
        return jsonify(
            {
                "id": readout.id,
                "sensor_id": readout.sensor_id,
                "type": readout.type,
                "value": readout.value,
                "timestamp": readout.timestamp.isoformat() + "Z",
            }
        ), 201

    # --- Command for creating the first admin ---
    # Usage:
    #   flask --app app create-admin --username admin --password 'secret'
    #   ADMIN_USERNAME=admin ADMIN_PASSWORD=secret flask --app app create-admin
    #   flask --app app create-admin   (asks interactively)

    @app.cli.command("create-admin")
    @click.option("--username", default=None, help="Administrator username")
    @click.option("--password", default=None, help="Administrator password")
    def create_admin(username, password):
        """Create or update an administrator account (is_admin=True)."""
        username = username or os.environ.get("ADMIN_USERNAME")
        if not username:
            username = click.prompt("Admin username")
        username = username.strip()
        if not username:
            raise click.ClickException("Username cannot be empty.")

        password = password or os.environ.get("ADMIN_PASSWORD")
        if not password:
            password = click.prompt("Admin password", hide_input=True, confirmation_prompt=True)
        if not password:
            raise click.ClickException("Password cannot be empty.")

        user = User.query.filter_by(username=username).first()
        if user:
            user.set_password(password)
            user.is_admin = True
            db.session.commit()
            click.echo(f"Updated existing user '{username}' (granted is_admin=True).")
        else:
            user = User(username=username, is_admin=True)
            user.set_password(password)
            db.session.add(user)
            db.session.commit()
            click.echo(f"Created administrator '{username}'.")

    return app


if __name__ == "__main__":
    app = create_app()
    app.run(debug=True, host='0.0.0.0')