// This plugin loads "defs.txt" and applies the therein contained commands
extern crate regex;
use bevy::prelude::*;
use bevy_xpbd_3d::prelude::*;
use bevy::math::DVec3;
use crate::{actor, chat, hud, nature, world};
use regex::Regex;
use std::f32::consts::PI;
use std::f64::consts::PI as PI64;
use std::collections::HashMap;

pub struct CommandsPlugin;
impl Plugin for CommandsPlugin {
    fn build(&self, app: &mut App) {
        app.add_systems(Startup, load_defs);
        app.add_systems(Update, spawn_entities);
        app.add_event::<SpawnEvent>();
    }
}

#[derive(Event)] pub struct SpawnEvent(ParserState);
#[derive(PartialEq, Clone)]
enum DefClass {
    Actor,
    Chat,
    None,
}

#[derive(Clone)]
struct ParserState {
    class: DefClass,

    // Generic fields
    name: Option<String>,
    chat: String,

    // Actor fields
    id: String,
    pos: DVec3,
    model: String,
    model_scale: f32,
    rotation: Quat,
    velocity: DVec3,
    angular_momentum: DVec3,
    pronoun: String,
    is_sphere: bool,
    is_player: bool,
    is_lifeform: bool,
    is_alive: bool,
    is_suited: bool,
    is_vehicle: bool,
    is_clickable: bool,
    has_physics: bool,
    wants_maxrotation: Option<f64>,
    wants_maxvelocity: Option<f64>,
    collider_is_mesh: bool,
    thrust_forward: f32,
    thrust_sideways: f32,
    thrust_back: f32,
    reaction_wheels: f32,
    warmup_seconds: f32,
    engine_type: actor::EngineType,
    oxygen: f32,
    mass: f64,
    collider: Collider,
    camdistance: f32,
    suit_integrity: f32,
    light_brightness: f32,
    light_color: Option<Color>,

    // Chat fields
    delay: f64,
    text: String,
    level: String,
    label: String,
    goto: String,
    is_choice: bool,
    stores_item: bool,
    script: String,
    script_parameter: String,
    script_parameter2: String,
}
impl Default for ParserState {
    fn default() -> Self {
        let default_actor = actor::Actor::default();
        let default_engine = actor::Engine::default();
        Self {
            class: DefClass::None,
            name: None,
            chat: "".to_string(),

            id: "".to_string(),
            pos: DVec3::new(0.0, 0.0, 0.0),
            model: "".to_string(),
            model_scale: 1.0,
            rotation: Quat::IDENTITY,
            velocity: DVec3::splat(0.0),
            angular_momentum: DVec3::new(0.03, 0.3, 0.09),
            pronoun: "they/them".to_string(),
            is_sphere: false,
            is_player: false,
            is_lifeform: false,
            is_alive: false,
            is_suited: false,
            is_vehicle: false,
            is_clickable: true,
            has_physics: true,
            wants_maxrotation: None,
            wants_maxvelocity: None,
            collider_is_mesh: false,
            thrust_forward: default_engine.thrust_forward,
            thrust_sideways: default_engine.thrust_forward,
            thrust_back: default_engine.thrust_back,
            reaction_wheels: default_engine.reaction_wheels,
            warmup_seconds: default_engine.warmup_seconds,
            engine_type: default_engine.engine_type,
            oxygen: nature::OXY_D,
            mass: 1.0,
            collider: Collider::sphere(1.0),
            camdistance: default_actor.camdistance,
            suit_integrity: 1.0,
            light_brightness: 0.0,
            light_color: None,

            delay: 0.0,
            text: "".to_string(),
            level: "chat".to_string(),
            label: "".to_string(),
            goto: "".to_string(),
            is_choice: false,
            stores_item: false,
            script: "".to_string(),
            script_parameter: "".to_string(),
            script_parameter2: "".to_string(),
        }
    }
}
impl ParserState {
    fn reset_message(&mut self) {
        let default = ParserState::default();
        self.label = default.label;
        self.delay = default.delay;
        self.goto = default.goto;
        self.level = default.level;
        self.text = default.text;
        self.is_choice = default.is_choice;
    }
    fn as_chatbranch(&self) -> chat::ChatBranch {
        return chat::ChatBranch {
            id: self.chat.clone(),
            name: self.name.clone().unwrap_or("".to_string()),
            label: self.label.clone(),
            delay: self.delay.clone(),
            sound: if self.is_choice { "".to_string() } else { "chat".to_string() },
            level: self.level.clone(),
            reply: if self.is_choice { "".to_string() } else { self.text.clone() },
            choice: if self.is_choice { self.text.clone() } else { "".to_string() },
            goto: self.goto.clone(),
            script: self.script.clone(),
            script_parameter: self.script_parameter.clone(),
            script_parameter2: self.script_parameter2.clone(),
        }
    }
}

pub fn load_defs(
    mut ew_spawn: EventWriter<SpawnEvent>,
) {
    let re1 = Regex::new(r"^\s*([a-z_-]+)\s+(.*)$").unwrap();
    let re2 = Regex::new("\"([^\"]*)\"|(-?[0-9]+[0-9e-]*(?:\\.[0-9e-]+)?)|([a-zA-Z_-][a-zA-Z0-9_-]*)").unwrap();
    let defs_string = include_str!("defs.txt");
    let mut lines = defs_string.lines();
    let mut state = ParserState::default();
    let mut command;
    let mut parameters;
    let mut id2pos: HashMap<String, DVec3> = HashMap::new();

    let mut line_nr = -1;
    while let Some(line) = lines.next() {
        line_nr += 1;
        let caps = re1.captures(line);
        if caps.is_none() {
            if line.trim() != "" {
                error!("Syntax Error in definitions line {}: `{}`", line_nr, line);
            }
            continue;
        }
        if let Some(caps) = caps {
            command = caps.get(1).unwrap().as_str();
            parameters = caps.get(2).unwrap().as_str();
        }
        else {
            error!("Failed to read regex captures in line {}: `{}`", line_nr, line);
            continue;
        }

        let mut parts: Vec<&str> = Vec::new();
        parts.push(command);
        for caps in re2.captures_iter(parameters) {
            if let Some(part) = caps.get(1) {
                parts.push(&part.as_str());
            }
            if let Some(part) = caps.get(2) {
                parts.push(&part.as_str());
            }
            if let Some(part) = caps.get(3) {
                parts.push(&part.as_str());
            }
        }

        match parts.as_slice() {
            // Parsing actors
            ["actor", x, y, z, model] => {
                ew_spawn.send(SpawnEvent(state));
                state = ParserState::default();
                state.class = DefClass::Actor;
                state.model = model.to_string();
                if let (Ok(x_float), Ok(y_float), Ok(z_float)) =
                        (x.parse::<f64>(), y.parse::<f64>(), z.parse::<f64>()) {
                    state.pos = DVec3::new(x_float, y_float, z_float);
                }
                else {
                    error!("Can't parse coordinates as floats in def: {line}");
                    state = ParserState::default();
                    continue;
                }
            }
            ["relativeto", id] => {
                match id2pos.get(&id.to_string()) {
                    Some(pos) => {
                        state.pos += *pos;
                    }
                    None => {
                        error!("Specified `relativeto` command but could not find id `{id}`");
                        continue;
                    }
                }
            }
            ["orbit", radius_str, phase_str] => {
                if let (Ok(r), Ok(phase)) = (radius_str.parse::<f64>(), phase_str.parse::<f64>()) {
                    let phase_deg = phase * PI64 * 2.0;
                    state.pos = DVec3::new(
                        state.pos.x + r * phase_deg.cos(),
                        state.pos.y,
                        state.pos.z + r * phase_deg.sin(),
                    );
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["sphere", "yes"] => {
                state.is_sphere = true;
            }
            ["id", id] => {
                state.id = id.to_string();
                id2pos.insert(state.id.clone(), state.pos.clone());
            }
            ["alive", "yes"] => {
                state.is_alive = true;
                state.is_lifeform = true;
                state.is_suited = true;
            }
            ["vehicle", "yes"] => {
                state.is_vehicle = true;
            }
            ["clickable", "no"] => {
                state.is_clickable = false;
            }
            ["moon", "yes"] => {
                state.model_scale *= 3.0;
            }
            ["oxygen", amount] => {
                if let Ok(amount) = amount.parse::<f32>() {
                    state.is_lifeform = true;
                    state.is_suited = true;
                    state.oxygen = amount;
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["pronoun", pronoun] => {
                state.pronoun = pronoun.to_string();
            }
            ["chatid", chat] => {
                state.chat = chat.to_string();
            }
            ["scale", scale] => {
                if let Ok(scale_float) = scale.parse::<f32>() {
                    state.model_scale = scale_float;
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["radius", radius] => {
                // like scale, just doubled size
                if let Ok(radius_float) = radius.parse::<f32>() {
                    state.model_scale = 2.0 * radius_float;
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["rotationx", rotation_x] => {
                if let Ok(rotation_x_float) = rotation_x.parse::<f32>() {
                    state.rotation *= Quat::from_rotation_x(PI * rotation_x_float);
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["rotationy", rotation_y] => {
                if let Ok(rotation_y_float) = rotation_y.parse::<f32>() {
                    state.rotation *= Quat::from_rotation_y(PI * rotation_y_float);
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["rotationz", rotation_z] => {
                if let Ok(rotation_z_float) = rotation_z.parse::<f32>() {
                    state.rotation *= Quat::from_rotation_z(PI * rotation_z_float);
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["velocity", x, y, z] => {
                if let (Ok(x_float), Ok(y_float), Ok(z_float)) =
                        (x.parse::<f64>(), y.parse::<f64>(), z.parse::<f64>()) {
                    state.velocity = DVec3::new(x_float, y_float, z_float);
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["angularmomentum", x, y, z] => {
                if let (Ok(x_float), Ok(y_float), Ok(z_float)) =
                        (x.parse::<f64>(), y.parse::<f64>(), z.parse::<f64>()) {
                    state.angular_momentum = DVec3::new(x_float, y_float, z_float);
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["thrust", forward, back, sideways, reaction_wheels, warmup_time] => {
                if let (Ok(forward_float), Ok(back_float), Ok(sideways_float), Ok(reaction_wheels_float), Ok(warmup_time_float)) = (forward.parse::<f32>(), back.parse::<f32>(), sideways.parse::<f32>(), reaction_wheels.parse::<f32>(), warmup_time.parse::<f32>()) {
                    state.thrust_forward = forward_float;
                    state.thrust_back = back_float;
                    state.thrust_sideways = sideways_float;
                    state.reaction_wheels = reaction_wheels_float;
                    state.warmup_seconds = warmup_time_float;
                }
            }
            ["engine", "rocket"] => {
                state.engine_type = actor::EngineType::Rocket;
            }
            ["engine", "ion"] => {
                state.engine_type = actor::EngineType::Ion;
            }
            ["engine", "monopropellant"] => {
                state.engine_type = actor::EngineType::Monopropellant;
            }
            ["health", value] => {
                if let Ok(value_float) = value.parse::<f32>() {
                    state.suit_integrity = value_float;
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["mass", value] => {
                if let Ok(value_float) = value.parse::<f64>() {
                    state.mass = value_float;
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["physics", "off"] => {
                state.has_physics = false;
            }
            ["collider", "sphere", radius] => {
                if let Ok(radius_float) = radius.parse::<f64>() {
                    state.collider = Collider::sphere(radius_float);
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["collider", "capsule", height, radius] => {
                if let (Ok(height_float), Ok(radius_float)) = (height.parse::<f64>(), radius.parse::<f64>()) {
                    state.collider = Collider::capsule(height_float, radius_float);
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["collider", "mesh"] => {
                state.collider_is_mesh = true;
            }
            ["player", "yes"] => {
                state.is_player = true;
                state.is_alive = true;
            }
            ["camdistance", value] => {
                if let Ok(value_float) = value.parse::<f32>() {
                    state.camdistance = value_float;
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["light", color_hex, brightness] => {
                if let Ok(brightness_float) = brightness.parse::<f32>() {
                    if let Ok(color) = Color::hex(color_hex) {
                        state.light_color = Some(color);
                        state.light_brightness = brightness_float;
                    }
                    else {
                        error!("Can't parse hexadecimal color code: {line}");
                        continue;
                    }
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["wants", "maxrotation", value] => {
                // NOTE: requires an engine to slow down velocity
                if let Ok(value_float) = value.parse::<f64>() {
                    state.wants_maxrotation = Some(value_float);
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }
            ["wants", "maxvelocity", value] => {
                // NOTE: requires an engine to slow down velocity
                if let Ok(value_float) = value.parse::<f64>() {
                    state.wants_maxvelocity = Some(value_float);
                }
                else {
                    error!("Can't parse float: {line}");
                    continue;
                }
            }

            // Parsing chats
            ["chat", chat_name] => {
                debug!("Registering chat: {}", chat_name);
                ew_spawn.send(SpawnEvent(state));
                state = ParserState::default();
                state.class = DefClass::Chat;
                state.chat = chat_name.to_string();
            }
            ["name", name] => {
                debug!("Registering name: {}", name);
                state.name = Some(name.to_string());
            }
            ["msg", sleep, text] => {
                debug!("Registering message (sleep={}): {}", sleep, text);
                ew_spawn.send(SpawnEvent(state.clone()));
                if let Ok(sleep_float) = sleep.parse::<f64>() {
                    state.delay = sleep_float;
                    state.text = text.to_string();
                    state.stores_item = true;
                    state.is_choice = false;
                } else {
                    error!("The 'sleep' value for this message is not a float: {}", line);
                    continue;
                }
            }
            ["msg", sleep, label, goto, text] => {
                debug!("Registering message (sleep={}): {}", sleep, text);
                ew_spawn.send(SpawnEvent(state.clone()));
                state.reset_message();
                if let Ok(sleep_float) = sleep.parse::<f64>() {
                    state.delay = sleep_float;
                    state.text = text.to_string();
                    state.stores_item = true;
                    state.is_choice = false;
                    state.goto = goto.to_string();
                    state.label = label.to_string();
                } else {
                    error!("The 'sleep' value for this message is not a float: {}", line);
                    continue;
                }
            }
            ["choice", sleep, text] => {
                debug!("Registering choice (sleep={}): {}", sleep, text);
                ew_spawn.send(SpawnEvent(state.clone()));
                state.reset_message();
                if let Ok(sleep_float) = sleep.parse::<f64>() {
                    state.delay = sleep_float;
                    state.text = text.to_string();
                    state.stores_item = true;
                    state.is_choice = true;
                } else {
                    error!("The 'sleep' value for this message is not a float: {}", line);
                    continue;
                }
            }
            ["choice", sleep, label, goto, text] => {
                debug!("Registering choice (sleep={}): {}", sleep, text);
                ew_spawn.send(SpawnEvent(state.clone()));
                state.reset_message();
                if let Ok(sleep_float) = sleep.parse::<f64>() {
                    state.delay = sleep_float;
                    state.text = text.to_string();
                    state.stores_item = true;
                    state.is_choice = true;
                    state.goto = goto.to_string();
                    state.label = label.to_string();
                } else {
                    error!("The 'sleep' value for this message is not a float: {}", line);
                    continue;
                }
            }
            ["goto", label] => {
                debug!("Registering goto: {}", label);
                state.goto = label.to_string();
            }
            ["label", label] => {
                debug!("Registering label: {}", label);
                state.label = label.to_string();
            }
            ["lvl", level] => {
                debug!("Registering level: {}", level);
                state.level = level.to_string();
            }
            ["script", scriptname, parameter] => {
                state.script = scriptname.to_string();
                state.script_parameter = parameter.to_string();
                state.script_parameter2 = "".to_string();
            }
            ["script", scriptname, parameter, parameter2] => {
                state.script = scriptname.to_string();
                state.script_parameter = parameter.to_string();
                state.script_parameter2 = parameter2.to_string();
            }
            _ => {
                error!("No match for [{}]", parts.join(","));
            }
        }
    }
    ew_spawn.send(SpawnEvent(state));
}

fn spawn_entities(
    mut er_spawn: EventReader<SpawnEvent>,
    mut commands: Commands,
    asset_server: Res<AssetServer>,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    for state_wrapper in er_spawn.read() {
        let state = &state_wrapper.0;
        if state.class == DefClass::Chat {
            if state.stores_item {
                let mut chat = commands.spawn(state.as_chatbranch());
                chat.insert(world::DespawnOnPlayerDeath);
            }
        }
        else if state.class == DefClass::Actor {
            let mut actor = commands.spawn_empty();
            actor.insert(actor::Actor {
                id: state.id.clone(),
                name: state.name.clone(),
                camdistance: state.camdistance,
                ..default()
            });
            actor.insert(world::DespawnOnPlayerDeath);
            actor.insert(actor::HitPoints::default());
            actor.insert(Position::from(state.pos));
            actor.insert(Rotation::from(state.rotation));
            if state.is_sphere {
                let sphere_texture_handle: Handle<Image> = asset_server.load(format!("textures/{}.jpg", state.model));
                let sphere_handle = meshes.add(Sphere::default().mesh().uv(128, 128));
                let sphere_material_handle = materials.add(StandardMaterial {
                    base_color_texture: Some(sphere_texture_handle.clone()),
                    perceptual_roughness: 1.0,
                    metallic: 0.0,
                    ..default()
                });
                actor.insert(PbrBundle {
                    mesh: sphere_handle,
                    material: sphere_material_handle,
                    transform: Transform {
                        scale: Vec3::splat(state.model_scale),
                        ..default()
                    },
                    ..default()
                });
            } else {
                actor.insert(SceneBundle {
                    transform: Transform {
                        scale: Vec3::splat(state.model_scale),
                        ..default()
                    },
                    scene: asset_server.load(world::asset_name_to_path(state.model.as_str())),
                    ..default()
                });
            }

            // Physics Parameters
            if state.has_physics {
                let fix_scale: f64 = 1.0 / (state.model_scale as f64).powf(3.0);
                actor.insert(RigidBody::Dynamic);
                actor.insert(LinearVelocity(state.velocity));
                actor.insert(AngularVelocity(state.angular_momentum));
                actor.insert(ColliderDensity((state.mass * fix_scale) as f64));
                if state.collider_is_mesh {
                    actor.insert(AsyncSceneCollider::new(Some(
                        ComputedCollider::TriMesh
                        //ComputedCollider::ConvexDecomposition(VHACDParameters::default())
                    )));
                }
                else {
                    actor.insert(state.collider.clone());
                }
            }
            // TODO: angular velocity for objects without collisions, static objects

            // Optional Components
            if state.is_player {
                actor.insert(actor::Player);
                actor.insert(actor::PlayerCamera);
            }
            if state.is_player || state.is_vehicle {
                // used to apply mouse movement to actor rotation
                actor.insert(ExternalTorque::ZERO.with_persistence(false));
            }
            if state.is_lifeform {
                actor.insert(actor::LifeForm::default());
                actor.insert(actor::ExperiencesGForce::default());
                actor.insert(actor::Suit {
                    oxygen: state.oxygen,
                    oxygen_max: nature::OXY_D,
                    integrity: state.suit_integrity,
                    ..default()
                });
            }
            if state.is_clickable {
                actor.insert(hud::IsClickable);
            }
            if let Some(value) = state.wants_maxrotation {
                actor.insert(actor::WantsMaxRotation(value));
            }
            if let Some(value) = state.wants_maxvelocity {
                actor.insert(actor::WantsMaxVelocity(value));
            }
            if let Some(color) = state.light_color {
                actor.insert(PointLightBundle {
                    point_light: PointLight {
                        intensity: state.light_brightness,
                        color: color,
                        range: 100.0,
                        radius: 100.0,
                        ..default()
                    },
                    ..default()
                });
            }
            if !state.chat.is_empty() {
                actor.insert(chat::Talker {
                    conv_id: state.chat.clone(),
                    ..default()
                });
            }
            if state.is_vehicle {
                actor.insert(actor::Vehicle::default());
            }
            if state.is_vehicle || state.is_suited
                || state.thrust_forward > 0.0
                || state.thrust_sideways > 0.0
                || state.thrust_back > 0.0
                || state.reaction_wheels > 0.0
            {
                actor.insert(actor::Engine {
                    thrust_forward: state.thrust_forward,
                    thrust_back: state.thrust_back,
                    thrust_sideways: state.thrust_sideways,
                    reaction_wheels: state.reaction_wheels,
                    warmup_seconds: state.warmup_seconds,
                    engine_type: state.engine_type,
                    ..default()
                });
            }
        }
    }
}