use bevy::prelude::*;
use crate::{nature, settings, actor, audio, hud};

const MIN_INTERACT_DISTANCE: f32 = 30.0;

pub struct ActorPlugin;
impl Plugin for ActorPlugin {
    fn build(&self, app: &mut App) {
        app.register_type::<ChatBranch>();
        app.add_systems(FixedUpdate, (
            update_physics_lifeforms,
            update_physics_actors,
        ));
        app.add_systems(Update, (
            handle_new_conversations,
            handle_send_messages,
            handle_conversations,
            handle_input,
        ));
        app.add_event::<StartConversationEvent>();
        app.add_event::<SendMessageEvent>();
    }
}

#[derive(Event)]
pub struct StartConversationEvent {
    pub talker: Talker,
}

#[derive(Event)]
pub struct SendMessageEvent {
    pub conv_id: String,
    pub conv_label: String,
    pub text: String,
}

#[derive(Component)]
pub struct Actor {
    pub hp: f32,
    pub m: f32, // mass
    pub v: Vec3, // velocity
    pub angular_momentum: Quat,
}

impl Default for Actor {
    fn default() -> Self {
        Self {
            hp: 100.0,
            m: 100.0,
            v: Vec3::ZERO,
            angular_momentum: Quat::from_euler(EulerRot::XYZ, 0.001, 0.01, 0.003),
        }
    }
}

#[derive(Component)] pub struct Player;
#[derive(Component)] pub struct PlayerInConversation;
#[derive(Component)] pub struct InConversationWithPlayer;

#[derive(Debug)]
#[derive(Component, Reflect, Default)]
#[reflect(Component)]
pub struct ChatBranch {
    pub id: String,
    pub name: String,
    pub label: String,
    pub delay: f64,
    pub sound: String,
    pub level: String,
    pub reply: String,
    pub goto: String,
    pub choice: String,
}

#[derive(Component)]
pub struct Chat {
    pub id: String,
    pub label: String,
    pub timer: f64,
}

#[derive(Component)]
#[derive(Clone)]
pub struct Talker {
    pub conv_id: String,
}

#[derive(Component)]
pub struct LifeForm {
    pub adrenaline: f32,
    pub adrenaline_baseline: f32,
    pub adrenaline_jolt: f32,
}
impl Default for LifeForm { fn default() -> Self { Self {
    adrenaline: 0.3,
    adrenaline_baseline: 0.3,
    adrenaline_jolt: 0.0,
}}}

#[derive(Component)]
pub struct Suit {
    pub oxygen: f32,
    pub power: f32,
    pub oxygen_max: f32,
    pub power_max: f32,
    pub integrity: f32, // [0.0 - 1.0]
}
impl Default for Suit { fn default() -> Self { SUIT_SIMPLE } }

const SUIT_SIMPLE: Suit = Suit {
    power: 1e5,
    power_max: 1e5,
    oxygen: nature::OXY_D,
    oxygen_max: nature::OXY_D,
    integrity: 1e5,
};

pub fn update_physics_actors(
    time: Res<Time>,
    mut q_actors: Query<(&mut Actor, &mut Transform)>,
) {
    let d = time.delta_seconds();
    for (actor, mut transform) in q_actors.iter_mut() {
        transform.rotate(actor.angular_momentum);
        // TODO: animate only a step based on time between update:
        //transform.rotate(actor.angular_momentum.slerp(Quat::IDENTITY, d)); // not working
        transform.translation += d * actor.v;
    }
}

pub fn update_physics_lifeforms(
    time: Res<Time>,
    mut query: Query<(&mut LifeForm, &mut Suit)>,
) {
    let d = time.delta_seconds();
    for (mut lifeform, mut suit) in query.iter_mut() {
        if lifeform.adrenaline_jolt.abs() > 1e-3 {
            lifeform.adrenaline_jolt *= 0.99;
        }
        else {
            lifeform.adrenaline_jolt = 0.0
        }
        lifeform.adrenaline = (lifeform.adrenaline - 0.0001 + lifeform.adrenaline_jolt * 0.01).clamp(0.0, 1.0);

        let mut oxygen_drain = nature::OXY_S;
        let integr_threshold = 0.5;
        if suit.integrity < integr_threshold {
            // The oxygen drain from suit integrity scales with (2 - 2x)^4,
            // which is a function with ~16 at x=0 and 0 at x=1.
            // Furthermore, x is divided by the integrity threshold (e.g. 0.5)
            // to squeeze the function horizontally, and change the range for
            // the x parameter from [0-1] to [0-integritythreshold]
            //
            // 16 |.
            //    |.
            //    |'.
            //    | '.
            //    |   '..
            //    |______''....
            //    x=0         x=1
            let drain_scaling = (2.0 - 2.0 * suit.integrity / integr_threshold).powf(4.0);
            oxygen_drain += suit.oxygen * 0.01 * drain_scaling;
        }
        suit.oxygen = (suit.oxygen - oxygen_drain*d).clamp(0.0, suit.oxygen_max);
    }
}

pub fn handle_input(
    keyboard_input: Res<ButtonInput<KeyCode>>,
    settings: ResMut<settings::Settings>,
    query: Query<(&Talker, &Transform)>,
    player: Query<&Transform, With<actor::Player>>,
    mut ew_conv: EventWriter<StartConversationEvent>,
)
{
    if keyboard_input.just_pressed(settings.key_interact) {
        let mindist = MIN_INTERACT_DISTANCE * MIN_INTERACT_DISTANCE;
        if let Ok(player) = player.get_single() {
            for (talker, transform) in &query {
                if transform.translation.distance_squared(player.translation) <= mindist {
                    ew_conv.send(StartConversationEvent{talker: talker.clone()});
                    break;
                }
            }
        }
    }
}

pub fn handle_new_conversations(
    mut commands: Commands,
    mut er_conv: EventReader<StartConversationEvent>,
    mut ew_sfx: EventWriter<audio::PlaySfxEvent>,
    q_conv: Query<&Chat>,
    time: Res<Time>,
) {
    let label = "INIT";
    for event in er_conv.read() {
        // check for existing chats with this id
        let id = &event.talker.conv_id;
        let chats: Vec<&Chat> = q_conv.iter().filter(|c| c.id == *id).collect();
        if chats.len() > 0 {
            ew_sfx.send(audio::PlaySfxEvent(audio::Sfx::Ping));
            continue;
        }

        // no existing chats yet, let's create a new one
        commands.spawn(Chat {
            id: id.to_string(),
            label: label.to_string(),
            timer: time.elapsed_seconds_f64(),
        });
        break;
    }
}

pub fn handle_send_messages(
    mut commands: Commands,
    mut er_sendmsg: EventReader<SendMessageEvent>,
    mut ew_sfx: EventWriter<audio::PlaySfxEvent>,
    mut q_conv: Query<(Entity, &mut Chat)>,
    time: Res<Time>,
    chat_branches: Query<&ChatBranch>,
    mut log: ResMut<hud::Log>,
) {
    let now = time.elapsed_seconds_f64();

    for event in er_sendmsg.read() {
        for (entity, mut chat) in &mut q_conv {
            if chat.id != event.conv_id {
                continue;
            }
            if event.conv_label == "EXIT" {
                info!("Despawning chat.");
                commands.entity(entity).despawn();
                continue;
            }

            let branches: Vec<&ChatBranch> = chat_branches.iter()
                .filter(|branch| branch.id == event.conv_id
                        && branch.label == event.conv_label
                        && branch.choice == event.text)
                .collect();
            if branches.len() != 1 {
                error!("Expected 1 branch with ID '{}' and label '{}', but got {}! Aborting conversation.", chat.id, chat.label, branches.len());
                continue;
            }
            let branch = branches[0];
            // TODO despawn the choices

            if !branch.reply.is_empty() {
                match branch.level.as_str() {
                    "chat" => log.chat(branch.reply.clone(), branch.name.clone()),
                    "info" => log.info(branch.reply.clone()),
                    _ => (),
                }
            }

            chat.label = branch.goto.clone();
            chat.timer = now + branch.delay;
            if branch.sound != "" {
                let sfx = audio::str2sfx(branch.sound.as_str());
                ew_sfx.send(audio::PlaySfxEvent(sfx));
            }
            let choices: Vec<&ChatBranch> = chat_branches.iter()
                .filter(|branch| branch.id == chat.id && branch.label == chat.label)
                .collect();
            for choice in choices {
                if choice.choice.as_str() != hud::CHOICE_NONE {
                    commands.spawn(hud::ChoiceAvailable {
                        conv_id: choice.id.clone(),
                        conv_label: choice.label.clone(),
                        recipient: choice.name.clone(),
                        text: choice.choice.clone(),
                    });
                }
            }
        }
        break; // let's only handle one of these per frame
    }
}

pub fn handle_conversations(
    mut commands: Commands,
    mut log: ResMut<hud::Log>,
    mut q_conv: Query<(Entity, &mut Chat)>,
    mut ew_sfx: EventWriter<audio::PlaySfxEvent>,
    time: Res<Time>,
    chat_branches: Query<&ChatBranch>, // TODO: use Table for faster iteration?
) {
    let now = time.elapsed_seconds_f64();
    for (entity, mut chat) in &mut q_conv {
        if chat.label == "EXIT" {
            info!("Despawning chat.");
            commands.entity(entity).despawn();
            continue;
        }
        if now < chat.timer {
            continue;
        }

        let branches: Vec<&ChatBranch> = chat_branches.iter()
            .filter(|branch| branch.id == chat.id
                    && branch.label == chat.label
                    && branch.choice == "")
            .collect();
        if branches.len() != 1 {
            error!("Expected 1 branch with ID '{}' and label '{}', but got {}! Aborting conversation.", chat.id, chat.label, branches.len());
            continue;
        }
        let branch = branches[0];

        if !branch.reply.is_empty() {
            match branch.level.as_str() {
                "chat" => log.chat(branch.reply.clone(), branch.name.clone()),
                "info" => log.info(branch.reply.clone()),
                _ => (),
            }
        }

        if chat.label == "EXIT" {
            // TODO: isn't this dead code?
            continue;
        }
        chat.label = branch.goto.clone();
        if branch.sound != "" {
            let sfx = audio::str2sfx(branch.sound.as_str());
            ew_sfx.send(audio::PlaySfxEvent(sfx));
        }
        chat.timer = now + branch.delay;

        let choices: Vec<&ChatBranch> = chat_branches.iter()
            .filter(|branch| branch.id == chat.id && branch.label == chat.label)
            .collect();
        for choice in choices {
            if choice.choice.as_str() != hud::CHOICE_NONE {
                commands.spawn(hud::ChoiceAvailable {
                    conv_id: choice.id.clone(),
                    conv_label: choice.label.clone(),
                    recipient: choice.name.clone(),
                    text: choice.choice.clone(),
                });
            }
        }
    }
}