bottom/src/app/data_collection/processes.rs

use heim_common::{
	prelude::{StreamExt, TryStreamExt},
	units,
};
use std::{collections::HashMap, process::Command};

#[allow(dead_code)]
#[derive(Clone)]
pub enum ProcessSorting {
	CPU,
	MEM,
	PID,
	NAME,
}

impl Default for ProcessSorting {
	fn default() -> Self {
		ProcessSorting::CPU
	}
}

// Possible process info struct?
#[derive(Clone, Default)]
pub struct ProcessData {
	pub pid : u32,
	pub cpu_usage_percent : f64,
	pub mem_usage_percent : Option<f64>,
	pub mem_usage_mb : Option<u64>,
	pub command : String,
}

fn vangelis_cpu_usage_calculation(prev_idle : &mut f64, prev_non_idle : &mut f64) -> std::io::Result<f64> {
	// Named after this SO answer: https://stackoverflow.com/a/23376195
	let mut path = std::path::PathBuf::new();
	path.push("/proc");
	path.push("stat");

	let stat_results = std::fs::read_to_string(path)?;
	let first_line = stat_results.split('\n').collect::<Vec<&str>>()[0];
	let val = first_line.split_whitespace().collect::<Vec<&str>>();

	// SC in case that the parsing will fail due to length:
	if val.len() <= 10 {
		return Ok(1.0); // TODO: This is not the greatest...
	}

	let user : f64 = val[1].parse::<_>().unwrap_or(0_f64);
	let nice : f64 = val[2].parse::<_>().unwrap_or(0_f64);
	let system : f64 = val[3].parse::<_>().unwrap_or(0_f64);
	let idle : f64 = val[4].parse::<_>().unwrap_or(0_f64);
	let iowait : f64 = val[5].parse::<_>().unwrap_or(0_f64);
	let irq : f64 = val[6].parse::<_>().unwrap_or(0_f64);
	let softirq : f64 = val[7].parse::<_>().unwrap_or(0_f64);
	let steal : f64 = val[8].parse::<_>().unwrap_or(0_f64);
	let guest : f64 = val[9].parse::<_>().unwrap_or(0_f64);

	let idle = idle + iowait;
	let non_idle = user + nice + system + irq + softirq + steal + guest;

	let total = idle + non_idle;
	let prev_total = *prev_idle + *prev_non_idle;

	let total_delta : f64 = total - prev_total;
	let idle_delta : f64 = idle - *prev_idle;

	//debug!("Vangelis function: CPU PERCENT: {}", (total_delta - idle_delta) / total_delta * 100_f64);

	*prev_idle = idle;
	*prev_non_idle = non_idle;

	let result = if total_delta - idle_delta != 0_f64 { total_delta - idle_delta } else { 1_f64 };

	Ok(result) // This works, REALLY damn well.  The percentage check is within like 2% of the sysinfo one.
}

fn get_ordering<T : std::cmp::PartialOrd>(a_val : T, b_val : T, reverse_order : bool) -> std::cmp::Ordering {
	if a_val > b_val {
		if reverse_order {
			std::cmp::Ordering::Less
		}
		else {
			std::cmp::Ordering::Greater
		}
	}
	else if a_val < b_val {
		if reverse_order {
			std::cmp::Ordering::Greater
		}
		else {
			std::cmp::Ordering::Less
		}
	}
	else {
		std::cmp::Ordering::Equal
	}
}

async fn non_linux_cpu_usage(process : heim::process::Process) -> heim::process::ProcessResult<(heim::process::Process, heim_common::units::Ratio)> {
	let usage_1 = process.cpu_usage().await?;
	futures_timer::Delay::new(std::time::Duration::from_millis(100)).await?; // TODO: For windows, make it like the linux check
	let usage_2 = process.cpu_usage().await?;

	Ok((process, usage_2 - usage_1))
}

fn get_process_cpu_stats(pid : u32) -> std::io::Result<f64> {
	let mut path = std::path::PathBuf::new();
	path.push("/proc");
	path.push(&pid.to_string());
	path.push("stat");

	let stat_results = std::fs::read_to_string(path)?;
	let val = stat_results.split_whitespace().collect::<Vec<&str>>();
	let utime = val[13].parse::<f64>().unwrap_or(0_f64);
	let stime = val[14].parse::<f64>().unwrap_or(0_f64);

	//debug!("PID: {}, utime: {}, stime: {}", pid, utime, stime);

	Ok(utime + stime) // This seems to match top...
}

fn linux_cpu_usage(pid : u32, cpu_usage : f64, previous_pid_stats : &mut HashMap<String, f64>) -> std::io::Result<f64> {
	// Based heavily on https://stackoverflow.com/a/23376195 and https://stackoverflow.com/a/1424556
	let before_proc_val : f64 = if previous_pid_stats.contains_key(&pid.to_string()) {
		*previous_pid_stats.get(&pid.to_string()).unwrap_or(&0_f64)
	}
	else {
		0_f64
	};
	let after_proc_val = get_process_cpu_stats(pid)?;

	/*debug!(
		"PID - {} - Before: {}, After: {}, CPU: {}, Percentage: {}",
		pid,
		before_proc_val,
		after_proc_val,
		cpu_usage,
		(after_proc_val - before_proc_val) / cpu_usage * 100_f64
	);*/

	let entry = previous_pid_stats.entry(pid.to_string()).or_insert(after_proc_val);
	*entry = after_proc_val;
	Ok((after_proc_val - before_proc_val) / cpu_usage * 100_f64)
}

fn convert_ps(process : &str, cpu_usage_percentage : f64, prev_pid_stats : &mut HashMap<String, f64>) -> std::io::Result<ProcessData> {
	if process.trim().to_string().is_empty() {
		return Ok(ProcessData {
			pid : 0,
			command : "".to_string(),
			mem_usage_percent : None,
			mem_usage_mb : None,
			cpu_usage_percent : 0_f64,
		});
	}

	let pid = (&process[..11]).trim().to_string().parse::<u32>().unwrap_or(0);
	let command = (&process[11..61]).trim().to_string();
	let mem_usage_percent = Some((&process[62..]).trim().to_string().parse::<f64>().unwrap_or(0_f64));

	Ok(ProcessData {
		pid,
		command,
		mem_usage_percent,
		mem_usage_mb : None,
		cpu_usage_percent : linux_cpu_usage(pid, cpu_usage_percentage, prev_pid_stats)?,
	})
}

pub async fn get_sorted_processes_list(prev_idle : &mut f64, prev_non_idle : &mut f64, prev_pid_stats : &mut HashMap<String, f64>) -> Result<Vec<ProcessData>, heim::Error> {
	let mut process_vector : Vec<ProcessData> = Vec::new();

	if cfg!(target_os = "linux") {
		// Linux specific - this is a massive pain... ugh.

		let ps_result = Command::new("ps")
			.args(&["-axo", "pid:10,comm:50,%mem:5", "--noheader"])
			.output()
			.expect("Failed to execute.");
		let ps_stdout = String::from_utf8_lossy(&ps_result.stdout);
		let split_string = ps_stdout.split('\n');
		let cpu_usage = vangelis_cpu_usage_calculation(prev_idle, prev_non_idle).unwrap(); // TODO: FIX THIS ERROR CHECKING
		let process_stream = split_string.collect::<Vec<&str>>();

		for process in process_stream {
			if let Ok(process_object) = convert_ps(process, cpu_usage, prev_pid_stats) {
				if !process_object.command.is_empty() {
					process_vector.push(process_object);
				}
			}
		}
	}
	else if cfg!(target_os = "windows") {
		// Windows
		let mut process_stream = heim::process::processes().map_ok(non_linux_cpu_usage).try_buffer_unordered(std::usize::MAX);

		let mut process_vector : Vec<ProcessData> = Vec::new();
		while let Some(process) = process_stream.next().await {
			if let Ok(process) = process {
				let (process, cpu_usage) = process;
				let mem_measurement = process.memory().await;
				if let Ok(mem_measurement) = mem_measurement {
					process_vector.push(ProcessData {
						command : process.name().await.unwrap_or_else(|_| "".to_string()),
						pid : process.pid() as u32,
						cpu_usage_percent : f64::from(cpu_usage.get::<units::ratio::percent>()),
						mem_usage_percent : None,
						mem_usage_mb : Some(mem_measurement.rss().get::<units::information::megabyte>()),
					});
				}
			}
		}
	}
	else if cfg!(target_os = "macos") {
		// TODO: macOS
		debug!("Mac");
	}
	else {
		// TODO: Others?
		debug!("Else");
		// Solaris: https://stackoverflow.com/a/4453581
	}

	Ok(process_vector)
}

pub fn sort_processes(process_vector : &mut Vec<ProcessData>, sorting_method : &ProcessSorting, reverse_order : bool) {
	match sorting_method {
		// Always sort alphabetically first!
		ProcessSorting::CPU => {
			process_vector.sort_by(|a, b| get_ordering(&a.command, &b.command, false));
			process_vector.sort_by(|a, b| get_ordering(a.cpu_usage_percent, b.cpu_usage_percent, reverse_order));
		}
		ProcessSorting::MEM => {
			process_vector.sort_by(|a, b| get_ordering(&a.command, &b.command, false));
			process_vector.sort_by(|a, b| get_ordering(a.mem_usage_percent, b.mem_usage_percent, reverse_order));
		}
		ProcessSorting::PID => {
			process_vector.sort_by(|a, b| get_ordering(&a.command, &b.command, false));
			process_vector.sort_by(|a, b| get_ordering(a.pid, b.pid, reverse_order));
		}
		ProcessSorting::NAME => process_vector.sort_by(|a, b| get_ordering(&a.command, &b.command, reverse_order)),
	}
}