const run_process = require('../modules/run_process')
const database = require('../database/database')
const {is_proc_running, kill_proc} = require('./run_process')
const coordinator = require('./coordinator')
const wait_list = require('./wait_list')
const {free_app_port, free_webrtc_port, free_sfu_port} = require('./port_alloc')

const observer_timeout = 100
let pending_list = new wait_list([])

const start_observer = () => {
    check()
    setTimeout(() => start_observer(), observer_timeout)
}

// check sessions in parallel
const check_sessions = async (sessions) => {

    await Promise.all(sessions.map(async (session) => {
        let webrtc_running = is_proc_running(session.webrtc_pid)
        let app_running = is_proc_running(session.app_pid)
        
        if (webrtc_running && app_running) {
            return
        }

        // if something running kill process and skip remove from database
        if (!webrtc_running || !app_running) {
            // if session already in peding list skip
            if (pending_list.is_waiting(session.session_id)) {
                return
            }
            pending_list.add(session.session_id)

            // kill process if running
            kill_proc(session.webrtc_pid)
            kill_proc(session.app_pid)
            kill_proc(session.sfu_pid)
            // free ports allocated for processes
            free_webrtc_port(session.webrtc_port)
            free_app_port(session.app_port)
            free_sfu_port(session.sfu_port)
            
            let close_session_result = await coordinator.close_session(session)
            if (close_session_result) {
                await database.add_running_session_to_history(session.session_id)
                await database.remove_running_session(session.session_id)
            } else {
                console.error('can not connect to coordinator')
            }
            pending_list.remove(session.session_id)
        }
    }))
}

const check = async () => {
    let sessions = await database.get_running_sessions()

    if (!sessions) {
        return
    }

    check_sessions(sessions)
}

module.exports = {
    start_observer
}