use iced::{
    widget::{column, pick_list, row, text, text_input},
    Element, Sandbox, Settings,
};

use volute::{
    round,
    volume::{self, CubicMetre},
};

const DECIMAL_DIGITS: i8 = 4;

pub fn main() -> iced::Result {
    App::run(Settings::default())
}

#[derive(Default)]
struct App {
    displacement: CubicMetre,
    ui: UI,
}

#[derive(Default)]
struct UI {
    displacement: String,
    displacement_unit: volume::Unit,
}

impl App {
    fn set_displacement(&mut self, displacement: &str) {
        if displacement.len() == 0 {
            self.displacement.0 = 0.0;
            self.ui.displacement = "".to_string();
        } else if let Ok(val) = displacement.parse::<f64>() {
            self.displacement = CubicMetre::from_unit(self.ui.displacement_unit, val);
            self.ui.displacement = String::from(displacement);
        }
    }
}

impl UI {
    fn convert_displacement(&mut self, unit: volume::Unit) {
        if self.displacement.len() > 0 {
            self.displacement = format!(
                "{}",
                round(
                    volume::convert(
                        self.displacement.parse::<f64>().unwrap(),
                        self.displacement_unit,
                        unit,
                    ),
                    DECIMAL_DIGITS,
                ),
            );
        }
        self.displacement_unit = unit;
    }
}

impl Sandbox for App {
    type Message = Message;

    fn new() -> Self {
        Self::default()
    }

    fn title(&self) -> String {
        String::from("volute")
    }

    fn update(&mut self, message: Message) {
        match message {
            Message::Displacement(displacement) => {
                self.set_displacement(&displacement);
            }
            Message::DisplacementUnit(unit) => {
                self.ui.convert_displacement(unit);
            }
        }
    }

    fn view(&self) -> Element<Self::Message> {
        column![row![
            text("Displacement:"),
            text_input("2.0", &self.ui.displacement, Message::Displacement),
            pick_list(
                &volume::Unit::ALL[..],
                Some(self.ui.displacement_unit),
                Message::DisplacementUnit,
            ),
        ]]
        .into()
    }
}

#[derive(Debug, Clone)]
pub enum Message {
    Displacement(String),
    DisplacementUnit(volume::Unit),
}