SolarEnergy/central_backend/src/energy/consumption.rs

use crate::app_config::{AppConfig, ConsumptionBackend};
use rand::{thread_rng, Rng};
use std::num::ParseIntError;
use std::path::Path;

#[derive(thiserror::Error, Debug)]
pub enum ConsumptionError {
    #[error("The file that should contain the consumption does not exists!")]
    NonExistentFile,
    #[error("The file that should contain the consumption has an invalid content!")]
    FileInvalidContent(#[source] ParseIntError),
}

pub type EnergyConsumption = i32;

/// Get current electrical energy consumption
pub async fn get_curr_consumption() -> anyhow::Result<EnergyConsumption> {
    let backend = AppConfig::get()
        .consumption_backend
        .as_ref()
        .unwrap_or(&ConsumptionBackend::Constant { value: 300 });

    match backend {
        ConsumptionBackend::Constant { value } => Ok(*value),

        ConsumptionBackend::Random { min, max } => Ok(thread_rng().gen_range(*min..*max)),

        ConsumptionBackend::File { path } => {
            let path = Path::new(path);
            if !path.is_file() {
                return Err(ConsumptionError::NonExistentFile.into());
            }

            let content = std::fs::read_to_string(path)?;

            Ok(content
                .trim()
                .parse()
                .map_err(ConsumptionError::FileInvalidContent)?)
        }
    }
}