//! Login/logout and the mapping between network clients and characters.

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

use bevy::prelude::*;
use bevy_replicon::prelude::*;
use game_core::{
    GameData,
    components::*,
    protocol::{GameLog, Login},
};

use crate::{
    movement::MoveIntent,
    persistence::SavedCharacter,
    world::{SpawnPoint, WorldLayout, find_free_tile},
};

/// Which client controls a character. Server-only.
#[derive(Component, Clone, Copy, Debug)]
pub struct Controller(pub ClientId);

/// Online characters by client.
#[derive(Resource, Default)]
pub struct Players {
    pub by_client: HashMap<ClientId, Entity>,
}

/// Characters that are currently offline, by name. Persisted with the world.
#[derive(Resource, Default)]
pub struct CharacterStore(pub BTreeMap<String, SavedCharacter>);

pub const MAX_NAME_LEN: usize = 24;

pub fn tell(commands: &mut Commands, client: ClientId, text: impl Into<String>) {
    commands.server_trigger(ToClients {
        targets: SendTargets::Single(client),
        message: GameLog { text: text.into() },
    });
}

pub fn valid_name(name: &str) -> bool {
    let len = name.chars().count();
    (1..=MAX_NAME_LEN).contains(&len)
        && name.trim() == name
        && name
            .chars()
            .all(|c| c.is_alphanumeric() || c == ' ' || c == '_' || c == '-')
}

#[allow(clippy::too_many_arguments)]
pub fn on_login(
    login: On<FromClient<Login>>,
    mut commands: Commands,
    mut players: ResMut<Players>,
    mut store: ResMut<CharacterStore>,
    mut disconnects: MessageWriter<DisconnectRequest>,
    data: Res<GameData>,
    spawn: Res<SpawnPoint>,
    layout: Res<WorldLayout>,
    characters: Query<&Character>,
    buildings: Query<(&GridPos, &BuildingState), (With<Building>, Without<Character>)>,
) {
    let client = login.client_id;
    let name = login.message.name.clone();
    if players.by_client.contains_key(&client) {
        return;
    }
    let reject = |commands: &mut Commands,
                  disconnects: &mut MessageWriter<DisconnectRequest>,
                  reason: &str| {
        tell(commands, client, reason);
        if let ClientId::Client(entity) = client {
            disconnects.write(DisconnectRequest { client: entity });
        }
    };
    if !valid_name(&name) {
        reject(&mut commands, &mut disconnects, "Invalid character name.");
        return;
    }
    if characters.iter().any(|c| c.name == name) {
        reject(
            &mut commands,
            &mut disconnects,
            "That character is already online.",
        );
        return;
    }

    let (saved, returning) = match store.0.remove(&name) {
        Some(saved) => (saved, true),
        None => (new_character(&data, spawn.0), false),
    };
    let pos = find_free_tile(saved.pos, &layout.0, &buildings);
    let entity = commands
        .spawn((
            Replicated,
            Character { name: name.clone() },
            pos,
            Facing(saved.facing),
            saved.vitals,
            saved.inventory,
            saved.skills,
            Controller(client),
            MoveIntent::default(),
        ))
        .id();
    players.by_client.insert(client, entity);
    info!("{name} logged in ({client:?})");
    let greeting = if returning {
        format!("Welcome back, {name}.")
    } else {
        format!("Welcome to the station, {name}. Press H for help.")
    };
    tell(&mut commands, client, greeting);
}

fn new_character(data: &GameData, spawn: GridPos) -> SavedCharacter {
    let mut inventory = Inventory::default();
    if data.items.contains_key("apple") {
        inventory.add("apple", 2, data);
    }
    SavedCharacter {
        pos: spawn,
        facing: Default::default(),
        vitals: Vitals::default(),
        inventory,
        skills: Skills::default(),
    }
}

/// Stores the character of a disconnecting client and removes it from the world.
pub fn on_disconnect(
    remove: On<Remove, ConnectedClient>,
    mut commands: Commands,
    mut players: ResMut<Players>,
    mut store: ResMut<CharacterStore>,
    characters: Query<(&Character, &GridPos, &Facing, &Vitals, &Inventory, &Skills)>,
) {
    let Some(entity) = players.by_client.remove(&ClientId::Client(remove.entity)) else {
        return;
    };
    if let Ok((c, pos, facing, vitals, inventory, skills)) = characters.get(entity) {
        info!("{} logged out", c.name);
        store.0.insert(
            c.name.clone(),
            SavedCharacter {
                pos: *pos,
                facing: facing.0,
                vitals: vitals.clone(),
                inventory: inventory.clone(),
                skills: skills.clone(),
            },
        );
    }
    commands.entity(entity).despawn();
}

#[cfg(test)]
mod tests {
    use super::valid_name;

    #[test]
    fn names() {
        assert!(valid_name("Jane Doe"));
        assert!(valid_name("x_1-2"));
        assert!(!valid_name(""));
        assert!(!valid_name(" padded"));
        assert!(!valid_name("semi;colon"));
        assert!(!valid_name(&"a".repeat(25)));
    }
}