use std::time::Duration;

use metrics::{describe_gauge, gauge, Gauge};
use serialport::SerialPort;

pub struct Pli {
    port: Box<dyn SerialPort>,
    voltage_gauge: Gauge,
}

impl Pli {
    pub fn new(serial_port: String, baud_rate: u32) -> anyhow::Result<Self> {
        let port = serialport::new(serial_port, baud_rate)
            .timeout(Duration::from_millis(250))
            .open()?;

        describe_gauge!("pl_battery_voltage", "Battery voltage");
        let voltage_gauge = gauge!("pl_battery_voltage");
        Ok(Self {
            port,
            voltage_gauge,
        })
    }

    pub fn refresh(&mut self) {
        let batv = (self.read_ram(50) as f64) * (4. / 10.);
        self.voltage_gauge.set(batv);
    }

    fn send_command(&mut self, req: [u8; 4]) {
        self.port
            .write_all(&req)
            .expect("failed to write to serial port");
    }

    fn receive<const LENGTH: usize>(&mut self) -> [u8; LENGTH] {
        let mut buf = [0; LENGTH];
        match self.port.read_exact(&mut buf) {
            Ok(_) => {
                println!("got buf {buf:?}")
            }
            Err(e) => println!("read error: {e:#?}"),
        }
        buf
    }

    fn read_ram(&mut self, address: u8) -> u8 {
        self.send_command(command(20, address, 0));
        self.receive::<2>()[1]
    }
}

fn command(operation: u8, address: u8, data: u8) -> [u8; 4] {
    [operation, address, data, !operation]
}