//! ::::::::::::::
//! /sys/class/power_supply/hidpp_battery_8/uevent
//! ::::::::::::::
//! POWER_SUPPLY_NAME=hidpp_battery_8
//! POWER_SUPPLY_TYPE=Battery
//! POWER_SUPPLY_ONLINE=1
//! POWER_SUPPLY_STATUS=Discharging
//! POWER_SUPPLY_SCOPE=Device
//! POWER_SUPPLY_MODEL_NAME=M570
//! POWER_SUPPLY_MANUFACTURER=Logitech
//! POWER_SUPPLY_SERIAL_NUMBER=1028-26-d9-b5-38
//! POWER_SUPPLY_CAPACITY=65
use std::collections::HashMap;

use glob::glob;
use i3monkit::{Block, Widget, WidgetUpdate};
use thiserror::Error;

#[derive(Debug, Default)]
pub struct PowerSupply {}

const POWER_SUPPLY_GLOB: &'static str = "/sys/class/power_supply/*/uevent";

#[derive(Error, Debug)]
enum PowerSupplyError {
    #[error("IO error {0}")]
    IoError(#[from] std::io::Error),
    #[error("glob error {0}")]
    GlobError(#[from] glob::GlobError),
    #[error("pattern error {0}")]
    PatternError(#[from] glob::PatternError),
    #[error("UTF-8 error {0}")]
    Utf8Error(#[from] std::str::Utf8Error),
    #[error("parse number error {0}")]
    ParseIntErro(#[from] std::num::ParseIntError),
    #[error("parse error {0}")]
    ParseError(String),
}

impl PowerSupply {
    fn get_update(&mut self) -> Result<Vec<String>, PowerSupplyError> {
        const BATT_100: &'static str = "&#xf240;";
        const BATT_75: &'static str = "&#xf241;";
        const BATT_50: &'static str = "&#xf242;";
        const BATT_25: &'static str = "&#xf243;";
        const BATT_0: &'static str = "&#xf244;";

        let mut res = Vec::new();
        for ps in glob(POWER_SUPPLY_GLOB)? {
            let bytes = std::fs::read(&ps?)?;
            let values: HashMap<&str, &str> = std::str::from_utf8(&bytes)?
                .lines()
                .map(|l| {
                    l.split_once('=').ok_or(PowerSupplyError::ParseError(
                        "missing = in uevent line".to_string(),
                    ))
                })
                .collect::<Result<_, _>>()?;
            let cap: u32 = values
                .get("POWER_SUPPLY_CAPACITY")
                .unwrap_or(&"0")
                .parse()?;
            let power = if cap >= 90 {
                BATT_100
            } else if cap >= 70 {
                BATT_75
            } else if cap >= 40 {
                BATT_50
            } else if cap >= 20 {
                BATT_25
            } else {
                BATT_0
            };
            res.push(format!(
                "{} {}: <span face=\"pango:Font Awesome 5 Free\">{}</span>",
                values
                    .get("POWER_SUPPLY_MANUFACTURER")
                    .unwrap_or(&"Unknown mfg"),
                values
                    .get("POWER_SUPPLY_MODEL_NAME")
                    .unwrap_or(&"Unknown model"),
                power,
            ));
        }
        Ok(res)
    }
}

impl Widget for PowerSupply {
    fn update(&mut self) -> Option<WidgetUpdate> {
        match self.get_update() {
            Ok(statuses) => {
                let mut data = Block::new();
                data.use_pango();
                for status in statuses {
                    data.append_full_text(&status);
                }
                return Some(WidgetUpdate {
                    refresh_interval: std::time::Duration::new(1, 0),
                    data: Some(data),
                });
            }
            Err(err) => eprintln!("Failed to update: {}", err),
        }
        None
    }
}