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

from flask import Flask, jsonify, request

from config import sensors_database_uri
from models import Sensor, SensorReadout, db


def create_app():
    app = Flask(__name__)

    app.config["SQLALCHEMY_DATABASE_URI"] = sensors_database_uri()
    app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False

    db.init_app(app)

    # --- 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])

    @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

    # --- API: dashboard reads (public on the local machine) ---

    @app.route("/api/sensors/<int:sensor_id>/types")
    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")
    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")
    def api_sensor_readouts_hourly(sensor_id):
        type_ = request.args.get("type")
        range_ = request.args.get("range", "all")
        # The frontend sends the browser timezone (e.g. Europe/Warsaw), so
        # "today" means "since midnight local time", not 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()
        # today/24h return every measurement by default; the "hourly average"
        # checkbox forces hourly averages.
        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
                ]
            )
        # Other ranges: hourly average over the full local hour (correct
        # across DST changes), timestamp is the start of the hour in UTC
        # (the frontend appends "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)

    return app


if __name__ == "__main__":
    app = create_app()
    app.run(debug=True, host='127.0.0.1', port=8001)