use crate::Pms7003Data;

use anyhow::Result;
use log::{info, warn};
use std::sync::{Arc, Mutex};

use esp_idf_svc::hal::{
    delay::{FreeRtos, BLOCK},
    uart::UartDriver,
};

// u16::from_be_bytes is too verbose
fn get_u16(buf: &[u8]) -> u16 {
    ((buf[0] as u16) << 8) | buf[1] as u16
}

fn read_pm_data(buf: &[u8; 32]) -> Option<Pms7003Data> {
    let checksum: u16 = buf.iter().take(29).copied().map(u16::from).sum();
    let csum_target = get_u16(&buf[30..32]);
    if checksum != csum_target {
        warn!("Checksum from PMS7003 READ does not match, skipping read");
        return None;
    }
    Some(Pms7003Data {
        pm1_0_cf1:       get_u16(&buf[ 4..6 ]),
        pm2_5_cf1:       get_u16(&buf[ 6..8 ]),
        pm10_cf1:        get_u16(&buf[ 8..10]),
        pm1_0_atm:       get_u16(&buf[10..12]),
        pm2_5_atm:       get_u16(&buf[12..14]),
        pm10_atm:        get_u16(&buf[14..16]),
        particles_0_3um: get_u16(&buf[16..18]),
        particles_0_5um: get_u16(&buf[18..20]),
        particles_1_0um: get_u16(&buf[20..22]),
        particles_2_5um: get_u16(&buf[22..24]),
        particles_5_0um: get_u16(&buf[24..26]),
        particles_10um:  get_u16(&buf[26..28]),
    })
}

fn send_pms7003_command(uart: &UartDriver, cmd: u8, datah: u8, datal: u8) -> Result<()> {
    let mut command = [0x42u8, 0x4D, cmd, datah, datal, 0, 0];

    let checksum: u16 = command.iter().take(5).copied().map(u16::from).sum();
    command[5] = ((checksum >> 8) & 0xFF) as u8;
    command[6] = (checksum & 0xFF) as u8;

    uart.write(&command)?;
    Ok(())
}

pub fn sensors_task(pm_data: Arc<Mutex<Pms7003Data>>, uart: &UartDriver) -> Result<()> {
    info!("Staring UART PM Sensor Task");

    send_pms7003_command(uart, 0xE1, 0x00, 0x00)?;

    loop {
        send_pms7003_command(uart, 0xE2, 0x00, 0x00)?;

        let mut buf = [0_u8; 32];
        let len = uart.read(&mut buf, BLOCK)?;
        if len > 0 {
            if let Some(data) = read_pm_data(&buf) {
                let mut pm_data = pm_data.lock().unwrap();
                *pm_data = data;
            }
        } else {
            // info!("No bytes read");
        }
        uart.clear_rx()?;
        FreeRtos::delay_ms(5000);
    }
}