use std::{
    fmt::{self, Display},
    time::Instant,
};

pub enum DsmrMessageType {
    Water,
    Gas,
    Energy1,
    Energy2,
    Power,
}

#[derive(Debug)]
pub struct DsmrState {
    pub name: String,
    pub power: Option<f32>,
    pub power_total_tariff_1: Option<f32>,
    pub power_total_tariff_2: Option<f32>,
    pub gas_total: Option<f32>,
    pub water_total: Option<f32>,
    pub last_seen: Instant,
}

impl DsmrState {
    pub fn new(name: String) -> Self {
        DsmrState {
            name,
            power: None,
            power_total_tariff_1: None,
            power_total_tariff_2: None,
            gas_total: None,
            water_total: None,
            last_seen: Instant::now(),
        }
    }

    pub fn format_open_metrics(&self) -> impl Display + '_ {
        DsmrFormatter { device: self }
    }
}

struct DsmrFormatter<'a> {
    device: &'a DsmrState,
}

impl Display for DsmrFormatter<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let power_total = self.device.power_total_tariff_1.unwrap_or_default()
            + self.device.power_total_tariff_2.unwrap_or_default();
        if power_total > 0.0 {
            writeln!(
                f,
                "power_total_kwh{{name=\"{}\"}} {}",
                self.device.name, power_total
            )?;
        }

        if let Some(power) = self.device.power_total_tariff_1 {
            writeln!(
                f,
                "power_total_low_kwh{{name=\"{}\"}} {}",
                self.device.name, power
            )?;
        }

        if let Some(power) = self.device.power_total_tariff_2 {
            writeln!(
                f,
                "power_total_high_kwh{{name=\"{}\"}} {}",
                self.device.name, power
            )?;
        }

        if let Some(power) = self.device.power {
            writeln!(
                f,
                "power_watts{{name=\"{}\"}} {}",
                self.device.name,
                power * 1000.0
            )?;
        }

        if let Some(gas) = self.device.gas_total {
            writeln!(f, "gas_total_m3{{name=\"{}\"}} {}", self.device.name, gas)?;
        }

        if let Some(water) = self.device.water_total {
            writeln!(
                f,
                "water_total_m3{{name=\"{}\"}} {}",
                self.device.name, water
            )?;
        }

        Ok(())
    }
}