use std::collections::{HashMap, HashSet};

use crate::bahn_api::{
    basic_types::station_ids::{DbStopId, StationEvaNumber, StationIdRef},
    transport_modes::TransportModesSet,
};

pub struct Stations {
    pub stations: HashMap<StationEvaNumber, Station>,
}

pub struct Station {
    pub name: String,
    pub db_station_id: DbStopId,
    pub related_stations: HashSet<StationEvaNumber>,
    pub lat_lon: Option<(f64, f64)>,
    pub transport_modes: Option<TransportModesSet>,
    pub has_been_changed: bool,
}

impl Stations {
    pub fn new() -> Self {
        Self {
            stations: HashMap::new(),
        }
    }

    pub fn insert(&mut self, eva_number: StationEvaNumber, mut station: Station) {
        if let Some(prev) = self.stations.get_mut(&eva_number) {
            // partial update: if we had more information than the new `station` has,
            // keep parts of the old information, but wherever the new `station` has
            // information, use the newer information.
            #[allow(dead_code, unreachable_code)]
            fn never_called() -> Station {
                // NOTE: this is here in case the contents of `Station` change,
                // as a reminder that the partial update must be adjusted too.
                Station {
                    name: String::new(),
                    db_station_id: DbStopId(unreachable!()),
                    related_stations: HashSet::new(),
                    lat_lon: None,
                    transport_modes: None,
                    has_been_changed: true,
                }
            }
            prev.has_been_changed = true;
            prev.name = station.name;
            prev.db_station_id = station.db_station_id;
            for station in station.related_stations {
                prev.related_stations.insert(station);
            }
            if let Some(v) = station.lat_lon {
                prev.lat_lon = Some(v);
            }
            if let Some(v) = station.transport_modes {
                prev.transport_modes = Some(v);
            }
        } else {
            station.has_been_changed = true;
            self.stations.insert(eva_number, station);
        }
    }
    pub(super) fn insert_raw(&mut self, eva_number: StationEvaNumber, station: Station) {
        self.stations.insert(eva_number, station);
    }

    pub fn get(&self, eva_number: &StationEvaNumber) -> Option<&Station> {
        self.stations.get(eva_number)
    }
    pub fn get_mut(&mut self, eva_number: &StationEvaNumber) -> Option<&mut Station> {
        self.stations.get_mut(eva_number)
    }
}

impl<'a> From<(&'a StationEvaNumber, &'a Station)> for StationIdRef<'a> {
    fn from(value: (&'a StationEvaNumber, &'a Station)) -> Self {
        (value.0, &value.1.db_station_id).into()
    }
}
impl<'a> From<(&'a StationEvaNumber, &'a DbStopId)> for StationIdRef<'a> {
    fn from(value: (&'a StationEvaNumber, &'a DbStopId)) -> Self {
        StationIdRef {
            eva_number: value.0,
            db_station_id: &value.1,
        }
    }
}