use eframe::egui::{DragValue, Ui};
use rand::RngCore;
use serde::{Deserialize, Serialize};

use crate::{
    card::{Card, SettingsUi},
    register,
};

#[derive(Serialize, Deserialize)]
pub struct RamCardSettings {
    size: u16,
    start_addr: u16,
}

pub struct RamCard {
    ram: Vec<u8>,
    start_addr: u16,
}

impl Card for RamCard {
    fn new(settings: ron::Value) -> Result<RamCard, anyhow::Error> {
        let settings: RamCardSettings = settings.into_rust().unwrap();
        let mut ram = vec![0; settings.size as usize];
        rand::thread_rng().fill_bytes(&mut ram);
        Ok(Self {
            ram,
            start_addr: settings.start_addr,
        })
    }

    fn read_mem(&mut self, address: u16) -> Option<u8> {
        if address < self.start_addr {
            return None;
        }
        let offset = (address - self.start_addr) as usize;
        if offset >= self.ram.len() {
            return None;
        }
        Some(self.ram[offset])
    }

    fn write_mem(&mut self, address: u16, data: u8) -> Option<()> {
        if address < self.start_addr {
            return None;
        }
        let offset = (address - self.start_addr) as usize;
        if offset >= self.ram.len() {
            return None;
        }
        self.ram[offset] = data;
        Some(())
    }

    fn default_settings() -> String {
        ron::to_string(&RamCardSettings {
            size: 4096,
            start_addr: 0,
        })
        .unwrap()
    }

    fn get_settings(&self) -> String {
        ron::to_string(&RamCardSettings {
            size: self.ram.len() as u16,
            start_addr: self.start_addr,
        }).unwrap()
    }

    fn settings_ui(settings: ron::Value) -> anyhow::Result<impl SettingsUi>
    where
        Self: Sized,
    {
        Ok(RamCardSettingsUi {
            settings: settings.into_rust().unwrap(),
        })
    }
}

pub struct RamCardSettingsUi {
    settings: RamCardSettings,
}

impl SettingsUi for RamCardSettingsUi {
    fn draw_ui(&mut self, ui: &mut Ui) {
        ui.horizontal(|ui| {
            ui.label("Size");
            ui.add(DragValue::new(&mut self.settings.size).hexadecimal(4, false, true));
        });
        ui.horizontal(|ui| {
            ui.label("Start address");
            ui.add(DragValue::new(&mut self.settings.start_addr).hexadecimal(4, false, true));
        });
    }

    fn serialize_settings(&self) -> String {
        ron::to_string(&self.settings).unwrap()
    }
}

register!(RamCard, "RAM card");