//@ts-check
import * as fs from 'fs'
import * as path from 'path'

/**
 * @typedef {{ name: string, before: string[], after: string[], init(): undefined | Promise<undefined> }} InitScript
 */
export async function init() {

    const initdFiles = fs.readdirSync('/etc/init.d/')
    const initdScripts = initdFiles.filter( (v) => v.endsWith('.js'))

    /**
     * @type { Array<String> }
     */
    const finishedScripts = []

    /**
     * @type { Array<InitScript> }
     */
    const scripts = []

    for(const script of initdScripts) {
        const scriptCandidate = require(path.join('/etc/init.d/', script))
        if(scriptCandidate?.before && scriptCandidate?.after && scriptCandidate?.init)
            scripts.push({ ...scriptCandidate, name: script})
        else
            console.error(`Invalid(missing exports) script error :${script}`)
    }

    const befores = processBefores(scripts)

    let i = 0
    while(scripts.length) {
        const s = scripts[i % scripts.length]
        i += 1
        if(isSubSet(s.after, finishedScripts) && ( !befores[s.name] || isSubSet(befores[s.name], finishedScripts) )) {
            //on supprime ce service
            scripts.splice(scripts.indexOf(s), 1)
            const result = s.init()
            if(typeof result?.then === 'function') {
                await result
                finishedScripts.push(s.name)
            }
        }
    }
}

/**
 * @template T
 * @param {Array<T>} arraya
 * @param {Array<T>} arrayb
 */
function isSubSet(arraya, arrayb) {
    for(const a of arraya) {
        if(!arrayb.includes(a)) {
            return false
        }
    }
    return true
}

/**
 *
 * @param {Array<InitScript>} scripts
 * @returns {{ [key: string]: string[] }}
 */
function processBefores(scripts) {
    /**
     * @type {{ [key: string]: string[] }}
     */
    const result = {}
    for(const script of scripts) {
        for(const before of script.before){
            if(! result[before]) result[before] = [script.name]
            else result[before].push(script.name)
        }
    }
    return result
}