bsky-app/src/lib/async/revertible.ts
2023-05-22 16:35:37 -07:00

68 lines
2.3 KiB
TypeScript

import {runInAction} from 'mobx'
import {deepObserve} from 'mobx-utils'
import set from 'lodash.set'
const ongoingActions = new Set<any>()
/**
* This is a TypeScript function that optimistically updates data on the client-side before sending a
* request to the server and rolling back changes if the request fails.
* @param {T} model - The object or record that needs to be updated optimistically.
* @param preUpdate - `preUpdate` is a function that is called before the server update is executed. It
* can be used to perform any necessary actions or updates on the model or UI before the server update
* is initiated.
* @param serverUpdate - `serverUpdate` is a function that returns a Promise representing the server
* update operation. This function is called after the previous state of the model has been recorded
* and the `preUpdate` function has been executed. If the server update is successful, the `postUpdate`
* function is called with the result
* @param [postUpdate] - `postUpdate` is an optional callback function that will be called after the
* server update is successful. It takes in the response from the server update as its parameter. If
* this parameter is not provided, nothing will happen after the server update.
* @returns A Promise that resolves to `void`.
*/
export const updateDataOptimistically = async <
T extends Record<string, any>,
U,
>(
model: T,
preUpdate: () => void,
serverUpdate: () => Promise<U>,
postUpdate?: (res: U) => void,
): Promise<void> => {
if (ongoingActions.has(model)) {
return
}
ongoingActions.add(model)
const prevState: Map<string, any> = new Map<string, any>()
const dispose = deepObserve(model, (change, path) => {
if (change.observableKind === 'object') {
if (change.type === 'update') {
prevState.set(
[path, change.name].filter(Boolean).join('.'),
change.oldValue,
)
} else if (change.type === 'add') {
prevState.set([path, change.name].filter(Boolean).join('.'), undefined)
}
}
})
preUpdate()
dispose()
try {
const res = await serverUpdate()
runInAction(() => {
postUpdate?.(res)
})
} catch (error) {
runInAction(() => {
prevState.forEach((value, path) => {
set(model, path, value)
})
})
throw error
} finally {
ongoingActions.delete(model)
}
}