/*!
 * V4Fire Core
 * https://github.com/V4Fire/Core
 *
 * Released under the MIT license
 * https://github.com/V4Fire/Core/blob/master/LICENSE
 */

export type WatchPath = ObjectPropertyPath;

export type WatchDependencies =
	WatchPath[] |
	Dictionary<WatchPath[]> |
	Map<WatchPath, CanArray<WatchPath>>;

export interface Watcher<T extends object = object> {
	/**
	 * A proxy object to watch
	 */
	proxy: T;

	/**
	 * Sets a new watchable value for the proxy object by the specified path
	 *
	 * @param path
	 * @param value
	 */
	set(path: WatchPath, value: unknown): void;

	/**
	 * Deletes a watchable value from the proxy object by the specified path.
	 * To restore watching for this property, use `set`.
	 *
	 * @param path
	 */
	delete(path: WatchPath): void;

	/**
	 * Cancels watching for the proxy object
	 */
	unwatch(): void;
}

export interface PathModifier {
	(path: unknown[]): unknown[];
}

export interface WatchOptions {
	/**
	 * If true, then the callback of changing is also fired on mutations of nested properties
	 *
	 * @default `false`
	 * @example
	 * ```js
	 * const {proxy} = watch({a: {b: {c: 1}}}, {deep: true}, (mutations) => {
	 *   mutations.forEach(([value, oldValue, info]) => {
	 *     console.log(value, oldValue, info.path);
	 *   });
	 * });
	 *
	 * // 2 1 ['a', 'b', 'c']
	 * proxy.a.b.c = 2;
	 *
	 * // {c: 2} {e: 2} ['a', 'b']
	 * proxy.a.b = {e: 2};
	 * ```
	 */
	deep?: boolean;

	/**
	 * If true, then the callback of changing is also fired on mutations of properties from prototypes
	 *
	 * @default `false`
	 * @example
	 * ```js
	 * const {proxy} = watch(a: 1, {__proto__: {b: 1}}, {withProto: true}, (mutations) => {
	 *   mutations.forEach(([value, oldValue, info]) => {
	 *     console.log(value, oldValue, info.path, info.fromProto);
	 *   });
	 * });
	 *
	 * // 2 1 ['a'] false
	 * proxy.a = 2;
	 *
	 * // 2 1 ['b'] true
	 * proxy.b = 2;
	 * ```
	 */
	withProto?: boolean;

	/**
	 * If true, then all mutation events will be fired immediately.
	 * Notice, with enabling this option, the callback changes its interface:
	 *
	 * ```typescript
	 * // Before
	 * type Cb = (mutations: [[unknown, unknown, WatchHandlerParams]]) => any;
	 *
	 * // After
	 * type CbWithImmediate = (newValue: unknown, oldValue: unknown, info: WatchHandlerParams) => any;
	 * ```
	 *
	 * @default `false`
	 * @example
	 * ```js
	 * const {proxy} = watch(a: 1}, {immediate: true}, (value, oldValue, info) => {
	 *   console.log(value, oldValue, info.path);
	 * });
	 *
	 * // 2 1 ['a']
	 * proxy.a = 2;
	 * ```
	 */
	immediate?: boolean;

	/**
	 * The option enables or disables collapsing of mutation events.
	 * When it toggles to `true`, all mutation events fire as if they occur on top properties of the watchable object.
	 *
	 * ```js
	 * const {proxy} = watch({a: {b: {c: 1}}}, {collapse: true, deep: true}, (mutations) => {
	 *   mutations.forEach(([value, oldValue, info]) => {
	 *     console.log(value, oldValue, info.path);
	 *   });
	 * });
	 *
	 * // {b: {c: 2}} {b: {c: 2}} ['a', 'b', 'c']
	 * proxy.a.b.c = 2;
	 * ```
	 *
	 * When it toggles to `false,` and the watcher binds to the specified path, the callback takes a list of mutations.
	 * Otherwise, the callback takes only the last mutation.
	 *
	 * ```js
	 * const {proxy} = watch({a: {b: {c: 1}}}, 'a.b', {collapse: false}, (mutations) => {
	 *   mutations.forEach(([value, oldValue, info]) => {
	 *     console.log(value, oldValue, info.path, info.originalPath);
	 *   });
	 * });
	 *
	 * // 2 1 ['a', 'b'] ['a', 'b', 'c']
	 * proxy.a.b.c = 2;
	 *
	 * const {proxy: proxy2} = watch({a: {b: {c: 1}}}, 'a.b', (value, oldValue, info) => {
	 *   console.log(value, oldValue, info.path, info.originalPath);
	 * });
	 *
	 * // {c: 2} {c: 2} ['a', 'b'] ['a', 'b', 'c']
	 * proxy2.a.b.c = 2;
	 * ```
	 *
	 * @default `false`
	 */
	collapse?: boolean;

	/**
	 * A function that takes a path of the mutation event and returns a new path.
	 * The function is used when you want to mask one mutation to another one.
	 *
	 * @example
	 * ```js
	 * function pathModifier(path) {
	 *   return path.map((chunk) => chunk.replace(/^_/, ''));
	 * }
	 *
	 * const {proxy} = watch({a: 1, b: 2, _a: 1}, 'a', {pathModifier}, (mutations) => {
	 *   mutations.forEach(([value, oldValue, info]) => {
	 *     console.log(value, oldValue, info.path, info.originalPath);
	 *   });
	 * });
	 *
	 * // 2 1 ['a'], ['_a']
	 * proxy._a = 2;
	 * ```
	 */
	pathModifier?: PathModifier;

	/**
	 * A filter function for mutation events.
	 * The function allows skipping some mutation events.
	 *
	 * @example
	 * ```js
	 * function eventFilter(value, oldValue, info) {
	 *   return info.path[0] !== '_a';
	 * }
	 *
	 * const {proxy} = watch({a: 1, b: 2, _a: 1}, {eventFilter}, (mutations) => {
	 *   mutations.forEach(([value, oldValue, info]) => {
	 *     console.log(value, oldValue, info.path, info.originalPath);
	 *   });
	 * });
	 *
	 * // This mutation won't invoke our callback
	 * proxy._a = 2;
	 * ```
	 */
	eventFilter?: WatchHandler;

	/**
	 * Link to an object that should connect with the watched object, i.e.,
	 * changing of properties of the tied object, will also emit mutation events
	 *
	 * @example
	 * ```js
	 * const data = {
	 *   foo: 2
	 * };
	 *
	 * class Bla {
	 *   data = data;
	 *
	 *   constructor() {
	 *     watch(this.data, {tiedWith: this}, (val) => {
	 *       console.log(val);
	 *     });
	 *   }
	 * }
	 *
	 * const bla = new Bla();
	 * bla.foo = 3;
	 * ```
	 */
	tiedWith?: object;

	/**
	 * List of prefixes for paths to watch.
	 * This parameter can help to watch accessors.
	 *
	 * @example
	 * ```js
	 * const obj = {
	 *   get foo() {
	 *     return this._foo * 2;
	 *   },
	 *
	 *   _foo: 2
	 * };
	 *
	 * const {proxy} = watch(obj, 'foo', {prefixes: ['_']}, (value, oldValue, info) => {
	 *   console.log(value, oldValue, info.path, info.originalPath, info.parent);
	 * });
	 *
	 * // This mutation will invoke our callback
	 * proxy._foo++;
	 * ```
	 */
	prefixes?: string[];

	/**
	 * List of postfixes for paths to watch.
	 * This parameter can help to watch accessors.
	 *
	 * @example
	 * ```js
	 * const obj = {
	 *   get foo() {
	 *     return this.fooStore * 2;
	 *   },
	 *
	 *   fooStore: 2
	 * };
	 *
	 * const {proxy} = watch(obj, 'foo', {postfixes: ['Store']}, (value, oldValue, info) => {
	 *   console.log(value, oldValue, info.path, info.originalPath, info.parent);
	 * });
	 *
	 * // This mutation will invoke our callback
	 * proxy.fooStore++;
	 * ```
	 */
	postfixes?: string[];

	/**
	 * When providing the specific path to watch, this parameter can contain a list of dependencies for the watching path.
	 * This parameter can help to watch accessors.
	 *
	 * ```js
	 * const obj = {
	 *   get foo() {
	 *     return this.bla * this.baz;
	 *   },
	 *
	 *   bla: 2,
	 *   baz: 3
	 * };
	 *
	 * const {proxy} = watch(obj, 'foo', {dependencies: ['bla', 'baz']}, (value, oldValue, info) => {
	 *   console.log(value, oldValue, info.path, info.originalPath, info.parent);
	 * });
	 *
	 * // This mutation will invoke our callback
	 * proxy.bla++;
	 * ```
	 *
	 * When providing the specific path to watch, this parameter can contain an object or `Map` with lists of
	 * dependencies to watch.
	 *
	 * ```js
	 * const obj = {
	 *   foo: {
	 *     get value() {
	 *       return this.bla * this.baz;
	 *     }
	 *   },
	 *
	 *   bla: 2,
	 *   baz: 3
	 * };
	 *
	 * const depsAsObj = {
	 *   'foo.value': ['bla', 'baz']
	 * };
	 *
	 * const {proxy: proxy1} = watch(obj, {dependencies: depsAsObj}, (mutations) => {
	 *   mutations.forEach(([value, oldValue, info]) => {
	 *     console.log(value, oldValue, info.path, info.originalPath, info.parent);
	 *   });
	 * });
	 *
	 * // This mutation will fire an additional event for `foo.value`
	 * proxy1.bla++;
	 *
	 * const depsAsMap = new Map([
	 *   [
	 *     // A path to the property with dependencies
	 *     ['foo', 'value'],
	 *
	 *     // Dependencies
	 *     ['bla', 'baz']
	 *   ]
	 * ]);
	 *
	 * const {proxy: proxy2} = watch(obj, {dependencies: depsAsMap}, (mutations) => {
	 *   mutations.forEach(([value, oldValue, info]) => {
	 *     console.log(value, oldValue, info.path, info.originalPath, info.parent);
	 *   });
	 * });
	 *
	 * proxy2.baz++;
	 * ```
	 */
	dependencies?: WatchDependencies;

	/**
	 * Watch engine to use.
	 * By default, will be used proxy if supported, otherwise accessors.
	 */
	engine?: WatchEngine;
}

export interface WatchEngine {
	watch<T extends object>(
		obj: T,
		path: CanUndef<unknown[]>,
		handler: Nullable<RawWatchHandler>,
		handlers: WatchHandlersSet,
		opts?: WatchOptions
	): Watcher<T>;

	watch<T extends object>(
		obj: T,
		path: CanUndef<unknown[]>,
		handler: Nullable<RawWatchHandler>,
		handlers: WatchHandlersSet,
		opts: CanUndef<InternalWatchOptions>,
		root: object,
		top: object
	): T;

	set(obj: object, path: WatchPath, value: unknown, handlers: WatchHandlersSet): void;
	unset(obj: object, path: WatchPath, handlers: WatchHandlersSet): void;
}

export interface InternalWatchOptions extends WatchOptions {
	fromProto?: boolean | 1;
}

export interface WatchHandlerParentParams {
	value: unknown;
	oldValue: unknown;
	info: WatchHandlerParams;
}

/**
 * Parameters of a mutation event
 */
export interface RawWatchHandlerParams {
	/**
	 * Link to the object that is watched
	 */
	obj: object;

	/**
	 * Link to the root object of watching
	 */
	root: object;

	/**
	 * Link to the top property of watching
	 * (the first level property of the root)
	 */
	top?: object;

	/**
	 * True if the mutation has occurred on a prototype of the watched object
	 */
	fromProto: boolean;

	/**
	 * Path to a property that was changed
	 */
	path: unknown[];
}

/**
 * Extended parameters of a mutation event
 */
export interface WatchHandlerParams extends RawWatchHandlerParams {
	/**
	 * Information about the parent mutation event
	 */
	parent?: WatchHandlerParentParams;

	/**
	 * The original path to a property that was changed.
	 *
	 * @example
	 * ```js
	 * function pathModifier(path) {
	 *   return path.map((chunk) => chunk.replace(/^_/, ''));
	 * }
	 *
	 * const {proxy} = watch(a: 1, b: 2, _a: 1}, 'a', {pathModifier}, (mutations) => {
	 *   mutations.forEach(([value, oldValue, info]) => {
	 *     console.log(value, oldValue, info.path, info.originalPath);
	 *   });
	 * });
	 *
	 * // 2 1 ['a'], ['_a']
	 * proxy._a = 2;
	 * ```
	 */
	originalPath: unknown[];
}

export interface RawWatchHandler<NEW = unknown, OLD = NEW> {
	(newValue: CanUndef<NEW>, oldValue: CanUndef<OLD>, params: RawWatchHandlerParams): void;
}

export interface WatchHandler<NEW = unknown, OLD = NEW> {
	(newValue: CanUndef<NEW>, oldValue: CanUndef<OLD>, params: WatchHandlerParams): void;
}

export interface MultipleWatchHandler<NEW = unknown, OLD = NEW> {
	(mutations: Array<[CanUndef<NEW>, CanUndef<OLD>, WatchHandlerParams]>): void;
}

export type WatchHandlersSet = Set<RawWatchHandler>;