24cd1b2ea5
* Reload user settings when changed externally * Fix to not use any * Make sure listener doesn't already exist * Fix up projects reloading --------- Co-authored-by: Jonathan Tran <jonnytran@gmail.com>
80 lines
2.5 KiB
TypeScript
80 lines
2.5 KiB
TypeScript
import { isDesktop } from 'lib/isDesktop'
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import { reportRejection } from 'lib/trap'
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import { useEffect, useState, useRef } from 'react'
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type Path = string
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// Not having access to NodeJS functions has influenced the design a little.
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// There is some indirection going on because we can only pass data between
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// the NodeJS<->Browser boundary. The actual functions need to run on the
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// NodeJS side. Because EventEmitters come bundled with their listener
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// methods it complicates things because we can't just do
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// watcher.addListener(() => { ... }).
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export const useFileSystemWatcher = (
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callback: (path: Path) => Promise<void>,
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dependencyArray: Path[]
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): void => {
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// Track a ref to the callback. This is how we get the callback updated
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// across the NodeJS<->Browser boundary.
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const callbackRef = useRef<{ fn: (path: Path) => Promise<void> }>({
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fn: async (_path) => {},
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})
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useEffect(() => {
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callbackRef.current.fn = callback
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}, [callback])
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// Used to track if dependencyArrray changes.
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const [dependencyArrayTracked, setDependencyArrayTracked] = useState<Path[]>(
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[]
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)
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// On component teardown obliterate all watchers.
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useEffect(() => {
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// The hook is useless on web.
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if (!isDesktop()) return
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return () => {
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for (let path of dependencyArray) {
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window.electron.watchFileOff(path)
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}
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}
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}, [])
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function difference<T>(l1: T[], l2: T[]): [T[], T[]] {
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return [
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l1.filter((x) => Boolean(!l2.find((x2) => x2 === x))),
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l1.filter((x) => Boolean(l2.find((x2) => x2 === x))),
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]
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}
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const hasDiff =
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difference(dependencyArray, dependencyArrayTracked)[0].length !== 0
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// Removing 1 watcher at a time is only possible because in a filesystem,
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// a path is unique (there can never be two paths with the same name).
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// Otherwise we would have to obliterate() the whole list and reconstruct it.
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useEffect(() => {
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// The hook is useless on web.
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if (!isDesktop()) return
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if (!hasDiff) return
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const [pathsRemoved, pathsRemaining] = difference(
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dependencyArrayTracked,
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dependencyArray
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)
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for (let path of pathsRemoved) {
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window.electron.watchFileOff(path)
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}
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const [pathsAdded] = difference(dependencyArray, dependencyArrayTracked)
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for (let path of pathsAdded) {
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window.electron.watchFileOn(path, (_eventType: string, path: Path) => {
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callbackRef.current.fn(path).catch(reportRejection)
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})
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}
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setDependencyArrayTracked(pathsRemaining.concat(pathsAdded))
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}, [hasDiff])
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}
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