import { App, inject, InjectionKey, getCurrentInstance } from "vue"

/**
 * Vue Plugin Base
 *
 * - [Vue 3 Docs](https://vuejs.org/guide)
 *   - [Plugins](https://vuejs.org/guide/reusability/plugins.html)
 *   - [Writing a Plugin](https://vuejs.org/guide/reusability/plugins.html#writing-a-plugin)
 */
export class Plugin {
	/**
	 * Called automatically by `app.use(Plugin)`.
	 *
	 * ***Should not be called manually by the user***
	 *
	 * @internal
	 * @param app - Application that uses the plugin
	 */
	install(app: App, ...args: any[]): void {
		return
	}
}

/**
 * Injects or Provides the provided value
 * - Works in Vue Components and in pure TypeScript code
 */
function CreateInjector<T>(name: InjectionKey<T>, instance: T): T {
	return getCurrentInstance() ? inject(name) || instance : instance
}

/**
 * Types for {@link createUseHook}
 */
interface UseHook<T> {
	/**
	 * Injection Key for the given instance
	 *
	 * [Docs](https://vuejs.org/api/composition-api-dependency-injection.html)
	 */
	key: InjectionKey<T>
	/**
	 * Function for getting the instance in components or scripts
	 *
	 * ***Usage:***
	 * ```ts
	 * const { useHook } = createUseHook<TYPE>("NAME", INSTANCE)
	 * const instance = useHook()
	 * ```
	 */
	useHook: () => T
	/**
	 * Function for providing the instance to the app
	 * - Needs to run before `useHook` to provide the instance to the app
	 *
	 * ```ts
	 * const { provide } = createUseHook<TYPE>("NAME", INSTANCE)
	 *
	 * export class ExamplePlugin extends Plugin {
	 *     public readonly install = provide
	 * }
	 * ```
	 */
	provide: (app: App) => void
}

/**
 * Useful Utility for creating a UseHook for a Vue Plugin
 *
 * ***Usage:***
 * ```ts
 * import { createUseHook, Plugin } from "vvic-utils/types"
 * const { useHook, provide } = createUseHook<TYPE>("NAME", INSTANCE)
 *
 * export class ExamplePlugin extends Plugin {
 *     public readonly install = provide
 * }
 *
 * export default ExamplePlugin()
 * ```
 */
export function createUseHook<T>(name: string, instance: T): UseHook<T> {
	const key = Symbol(name) as InjectionKey<T>
	const provide = (app: App) => {
		try {
			app.provide(key, instance)
		} catch (error) {
			return
		}
	}
	const useHook = () => CreateInjector<T>(key, instance)
	return { key, useHook, provide }
}

/**
 * Small Utility for creating an install function with multiple provide functions from Use Hooks
 *
 * ***Usage:***
 * ```ts
 * import { createUseHook, createInstall, Plugin } from "vvic-utils/types"
 * const hook1 = createUseHook<TYPE_1>("1", INSTANCE_1)
 * const hook2 = createUseHook<TYPE_2>("2", INSTANCE_2)
 *
 * export class ExamplePlugin extends Plugin {
 *     public readonly install = createInstall(
 *         hook1.provide,
 *         hook2.provide
 *     )
 * }
 *
 * export default ExamplePlugin()
 * ```
 */
export function createInstall(...fn: ((app: App) => void)[]) {
	return (app: App) => {
		fn.forEach((f) => f(app))
	}
}