import {
	parseAutomergeUrl,
	type AutomergeUrl,
	type DocHandle,
	type HandleState,
} from "@automerge/automerge-repo/slim"
import {createEffect, createResource, useContext} from "solid-js"
import {access, type MaybeAccessor} from "@solid-primitives/utils"
import {RepoContext} from "./context.js"
import type {UseDocHandleOptions} from "./types.js"

const readyStates = ["ready", "deleted", "unavailable"] as HandleState[]
const badStates = ["deleted", "unavailable"] as HandleState[]

/**
 * get a
 * [DocHandle](https://automerge.org/automerge-repo/classes/_automerge_automerge_repo.DocHandle.html)
 * from an
 * [AutomergeUrl](https://automerge.org/automerge-repo/types/_automerge_automerge_repo.AutomergeUrl.html)
 * as a
 * [Resource](https://docs.solidjs.com/reference/basic-reactivity/create-resource).
 * Waits for the handle to be
 * [ready](https://automerge.org/automerge-repo/variables/_automerge_automerge_repo.HandleState-1.html).
 */
export default function useDocHandle<T>(
	url: MaybeAccessor<AutomergeUrl | undefined>,
	options?: UseDocHandleOptions
) {
	const contextRepo = useContext(RepoContext)

	if (!options?.repo && !contextRepo) {
		throw new Error("use outside <RepoContext> requires options.repo")
	}

	const repo = (options?.repo || contextRepo)!

	function getExistingHandle() {
		if (options?.["~skipInitialValue"]) return undefined
		const unwrappedURL = access(url)
		if (!unwrappedURL) return undefined
		const parsedURL = parseAutomergeUrl(unwrappedURL)
		const existingHandle = repo.handles[parsedURL.documentId]
		if (existingHandle?.isReady()) {
			return existingHandle as DocHandle<T>
		}
	}

	const [handle, {mutate}] = createResource(
		url,
		async url => {
			const handle = await repo.find<T>(url, {
				allowableStates: readyStates,
			})
			const reject = (state: HandleState) =>
				Promise.reject(new Error(`document not available: [${state}]`))

			if (handle.isReady()) {
				return handle
			} else if (handle.inState(badStates)) {
				return reject(handle.state)
			}

			return handle.whenReady(readyStates).then(() => {
				if (handle.isReady()) {
					return handle
				}
				return reject(handle.state)
			})
		},
		{
			initialValue: getExistingHandle(),
		}
	)

	createEffect(() => {
		if (!access(url)) {
			mutate()
		}
	})

	return handle
}