/*!
 * Copyright (c) Microsoft Corporation and contributors. All rights reserved.
 * Licensed under the MIT License.
 */

import { LazyPromise } from "@fluidframework/core-utils/internal";

import { IFluidDependencySynthesizer } from "./IFluidDependencySynthesizer.js";
import type {
	AsyncFluidObjectProvider,
	AsyncOptionalFluidObjectProvider,
	AsyncRequiredFluidObjectProvider,
	FluidObjectProvider,
	FluidObjectSymbolProvider,
} from "./types.js";

/**
 * DependencyContainer is similar to a IoC Container. It takes providers and will
 * synthesize an object based on them when requested.
 * @legacy
 * @beta
 */
export class DependencyContainer<TMap> implements IFluidDependencySynthesizer {
	// eslint-disable-next-line @typescript-eslint/no-explicit-any -- TODO: use a real type here
	private readonly providers = new Map<keyof TMap, FluidObjectProvider<any>>();
	private readonly parents: IFluidDependencySynthesizer[];
	public get IFluidDependencySynthesizer(): this {
		return this;
	}

	public constructor(...parents: (IFluidDependencySynthesizer | undefined)[]) {
		this.parents = parents.filter((v): v is IFluidDependencySynthesizer => v !== undefined);
	}

	/**
	 * Add a new provider
	 * @param type - Name of the Type T being provided
	 * @param provider - A provider that will resolve the T correctly when asked
	 * @throws If passing a type that's already registered
	 */
	public register<T extends keyof TMap = keyof TMap>(
		type: T,
		provider: FluidObjectProvider<Pick<TMap, T>>,
	): void {
		if (this.providers.has(type)) {
			throw new Error(
				`Attempting to register a provider of type ${String(type)} that already exists`,
			);
		}

		this.providers.set(type, provider);
	}

	/**
	 * Remove a provider
	 * @param type - Name of the provider to remove
	 */
	public unregister(type: keyof TMap): void {
		if (this.providers.has(type)) {
			this.providers.delete(type);
		}
	}

	/**
	 * {@inheritDoc (IFluidDependencySynthesizer:interface).synthesize}
	 */
	public synthesize<O, R = undefined | Record<string, never>>(
		optionalTypes: FluidObjectSymbolProvider<O>,
		requiredTypes: Required<FluidObjectSymbolProvider<R>>,
	): AsyncFluidObjectProvider<O, R> {
		// eslint-disable-next-line @typescript-eslint/consistent-type-assertions
		const base: AsyncFluidObjectProvider<O, R> = {} as AsyncFluidObjectProvider<O, R>;
		this.generateRequired<R>(base, requiredTypes);
		this.generateOptional<O>(base, optionalTypes);
		Object.defineProperty(base, IFluidDependencySynthesizer, { get: () => this });
		return base;
	}

	/**
	 * {@inheritDoc (IFluidDependencySynthesizer:interface).has}
	 * @param excludeParents - If true, exclude checking parent registries
	 */
	public has(type: string, excludeParents?: boolean): boolean {
		if (this.providers.has(type as keyof TMap)) {
			return true;
		}
		if (excludeParents !== true) {
			return this.parents.some((p: IFluidDependencySynthesizer) => p.has(type));
		}
		return false;
	}
	/**
	 * Get a provider for the given type.
	 * @param provider - The name of the provider to get
	 * @deprecated Needed for backwards compatability.
	 */
	private getProvider(provider: string & keyof TMap): PropertyDescriptor | undefined {
		// this was removed, but some partners have trouble with back compat where they
		// use invalid patterns with FluidObject and IFluidDependencySynthesizer
		// this is just for back compat until those are removed
		if (this.has(provider)) {
			if (this.providers.has(provider)) {
				return this.providers.get(provider);
			}
			for (const parent of this.parents) {
				if (parent instanceof DependencyContainer) {
					return parent.getProvider(provider);
				} else {
					// older implementations of the IFluidDependencySynthesizer exposed getProvider
					const maybeGetProvider = parent as { getProvider?(provider: string & keyof TMap) };
					if (maybeGetProvider?.getProvider !== undefined) {
						return maybeGetProvider.getProvider(provider);
					}
				}
			}
		}
	}

	private generateRequired<T>(
		base: AsyncRequiredFluidObjectProvider<T>,
		types: Required<FluidObjectSymbolProvider<T>>,
	): void {
		if (types === undefined) {
			return;
		}
		for (const key of Object.keys(types) as unknown as (keyof TMap)[]) {
			const provider = this.resolveProvider(key);
			if (provider === undefined) {
				throw new Error(
					`Object attempted to be created without registered required provider ${String(key)}`,
				);
			}
			Object.defineProperty(base, key, provider);
		}
	}

	private generateOptional<T>(
		base: AsyncOptionalFluidObjectProvider<T>,
		types: FluidObjectSymbolProvider<T>,
	): void {
		if (types === undefined) {
			return;
		}
		for (const key of Object.keys(types) as unknown as (keyof TMap)[]) {
			// back-compat: in 0.56 we allow undefined in the types, but we didn't before
			// this will keep runtime back compat, eventually we should support undefined properties
			// rather than properties that return promises that resolve to undefined
			const provider = this.resolveProvider(key) ?? { get: async () => undefined };
			Object.defineProperty(base, key, provider);
		}
	}

	private resolveProvider<T extends keyof TMap>(t: T): PropertyDescriptor | undefined {
		// If we have the provider return it
		// eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
		const provider = this.providers.get(t);
		if (provider === undefined) {
			for (const parent of this.parents) {
				// eslint-disable-next-line @typescript-eslint/consistent-type-assertions
				const sp = { [t]: t } as FluidObjectSymbolProvider<Pick<TMap, T>>;
				const syn = parent.synthesize<Pick<TMap, T>, Record<string, unknown>>(sp, {});
				const descriptor = Object.getOwnPropertyDescriptor(syn, t);
				if (descriptor !== undefined) {
					return descriptor;
				}
			}
			return undefined;
		}

		// The double nested gets are required for lazy loading the provider resolution
		if (typeof provider === "function") {
			return {
				// eslint-disable-next-line @typescript-eslint/promise-function-async
				get() {
					if (provider && typeof provider === "function") {
						return (
							Promise.resolve(this[IFluidDependencySynthesizer])
								// eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-call
								.then(async (fds): Promise<any> => provider(fds))
								// eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
								.then((p) => p?.[t])
						);
					}
				},
			};
		}
		return {
			get() {
				if (provider) {
					return new LazyPromise(async () => {
						return Promise.resolve(provider).then((p) => {
							if (p) {
								// eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
								return p[t];
							}
						});
					});
				}
			},
		};
	}
}