import * as v from "valibot"
import { type CustomBlockManifest, manifestSchema } from "./manifest.js"

const MANIFEST_URL = "custom_blocks.json"

// The schema accepts any string code. The type lists known codes for
// autocomplete, with an open string fallback for newer senders.
export const customBlockReadyErrorCodeSchema = v.string()

export type CustomBlockReadyErrorCode =
	| "manifest_unavailable"
	| "manifest_invalid"
	| (string & {})

export const customBlockReadyErrorSchema = v.object({
	code: customBlockReadyErrorCodeSchema,
	message: v.string(),
})

export type CustomBlockReadyError = v.InferOutput<
	typeof customBlockReadyErrorSchema
>

export type ManifestLoadResult =
	| {
			manifest: CustomBlockManifest | null
			error?: undefined
	  }
	| {
			manifest: null
			error: CustomBlockReadyError
	  }

/**
 * Attempts to load a `custom_blocks.json` manifest co-located with the bundle.
 * A missing manifest means the block has no declared data requirements.
 * Other failures return a structured error so the host can reject the manifest.
 * The SDK validates the manifest locally for author feedback; the host still
 * validates the ready message as the iframe trust boundary.
 */
export async function loadManifest(): Promise<ManifestLoadResult> {
	if (typeof fetch !== "function") {
		const message = `No fetch API available; cannot load ${MANIFEST_URL}.`
		console.warn(`[notion-custom-sdk] ${message}`)
		return {
			manifest: null,
			error: { code: "manifest_unavailable", message },
		}
	}
	let response: Response
	try {
		response = await fetch(MANIFEST_URL, { credentials: "omit" })
	} catch (error) {
		const message = `Could not fetch ${MANIFEST_URL}.`
		console.warn(`[notion-custom-sdk] ${message}`, error)
		return {
			manifest: null,
			error: { code: "manifest_unavailable", message },
		}
	}
	if (response.status === 404) {
		const message = `No manifest found at ${MANIFEST_URL} (status ${response.status}).`
		console.warn(`[notion-custom-sdk] ${message}`)
		return { manifest: null }
	}
	if (!response.ok) {
		const message = `Could not fetch ${MANIFEST_URL} (status ${response.status}).`
		console.warn(`[notion-custom-sdk] ${message}`)
		return {
			manifest: null,
			error: { code: "manifest_unavailable", message },
		}
	}
	let json: unknown
	try {
		json = await response.json()
	} catch (error) {
		const message = `Manifest at ${MANIFEST_URL} was not valid JSON.`
		console.warn(`[notion-custom-sdk] ${message}`, error)
		return { manifest: null, error: { code: "manifest_invalid", message } }
	}
	const parsed = v.safeParse(manifestSchema, json)
	if (!parsed.success) {
		const message = `Manifest at ${MANIFEST_URL} did not match schema.`
		console.warn(`[notion-custom-sdk] ${message}`, parsed.issues)
		return { manifest: null, error: { code: "manifest_invalid", message } }
	}
	return { manifest: parsed.output }
}