import {makeArray} from './array.ts';
import {ASet} from './aset.ts';

/**
 * Available methods:
 * * - All/Wildcard
 * n - None
 * c - Create
 * r - Read
 * u - Update
 * d - Delete
 * x - Execute
 */
export type Method = '*' | 'n' | 'c' | 'r' | 'u' | 'd' | 'x';

/**
 * Shorthand for creating Event from a string
 *
 * @example
 * ```ts
 * const event: Event = PE`users/system:*`;
 * ```
 *
 * @param {TemplateStringsArray} str String that will be parsed into Event
 * @param {string} args
 * @return {PathEvent} Event object
 */
export function PE(str: TemplateStringsArray, ...args: any[]) {
	const combined = [];
	for(let i = 0; i < str.length || i < args.length; i++) {
		if(str[i]) combined.push(str[i]);
		if(args[i]) combined.push(args[i]);
	}
	return new PathEvent(combined.join('/'));
}

/**
 * Shorthand for creating Event strings, ensures paths are correct
 *
 * @param {TemplateStringsArray} str
 * @param {string} args
 * @return {string}
 * @constructor
 */
export function PES(str: TemplateStringsArray, ...args: any[]) {
	let combined = [];
	for(let i = 0; i < str.length || i < args.length; i++) {
		if(str[i]) combined.push(str[i]);
		if(args[i]) combined.push(args[i]);
	}
	const [paths, methods] = combined.join('/').split(':');
	return PathEvent.toString(paths, <any>methods?.split(''));
}

export class PathError extends Error { }

/**
 * A event broken down into its core components for easy processing
 * Event Structure: `module/path/name:method`
 * Example: `users/system:crud` or `storage/some/path/file.txt:r`
 * Supports glob patterns: `users/*:r` or `storage/**:rw`
 */
export class PathEvent {
	/** First directory in path */
	module!: string;
	/** Entire path, including the module & name */
	fullPath!: string;
	/** Path including the name, excluding the module */
	path!: string;
	/** Last segment of path */
	name!: string;
	/** List of methods */
	methods!: ASet<Method>;
	/** Whether this path contains glob patterns */
	hasGlob!: boolean;

	/** Internal cache for PathEvent instances to avoid redundant parsing */
	private static pathEventCache: Map<string, PathEvent> = new Map();
	/** Cache for compiled permissions (path + required permissions → result) */
	private static permissionCache: Map<string, PathEvent> = new Map();
	/** Max size for permission cache before LRU eviction */
	private static readonly MAX_PERMISSION_CACHE_SIZE = 1000;

	/** All/Wildcard specified */
	get all(): boolean { return this.methods.has('*') }
	set all(v: boolean) { v ? this.methods = new ASet<Method>(['*']) : this.methods.delete('*'); }
	/** None specified */
	get none(): boolean { return this.methods.has('n') }
	set none(v: boolean) { v ? this.methods = new ASet<Method>(['n']) : this.methods.delete('n'); }
	/** Create method specified */
	get create(): boolean { return !this.methods.has('n') && (this.methods.has('*') || this.methods.has('c')) }
	set create(v: boolean) { v ? this.methods.delete('n').delete('*').add('c') : this.methods.delete('c'); }
	/** Execute method specified */
	get execute(): boolean { return !this.methods.has('n') && (this.methods.has('*') || this.methods.has('x')) }
	set execute(v: boolean) { v ? this.methods.delete('n').delete('*').add('x') : this.methods.delete('x'); }
	/** Read method specified */
	get read(): boolean { return !this.methods.has('n') && (this.methods.has('*') || this.methods.has('r')) }
	set read(v: boolean) { v ? this.methods.delete('n').delete('*').add('r') : this.methods.delete('r'); }
	/** Update method specified */
	get update(): boolean { return !this.methods.has('n') && (this.methods.has('*') || this.methods.has('u')) }
	set update(v: boolean) { v ? this.methods.delete('n').delete('*').add('u') : this.methods.delete('u'); }
	/** Delete method specified */
	get delete(): boolean { return !this.methods.has('n') && (this.methods.has('*') || this.methods.has('d')) }
	set delete(v: boolean) { v ? this.methods.delete('n').delete('*').add('d') : this.methods.delete('d'); }

	constructor(e: string | PathEvent) {
		if(typeof e == 'object') {
			Object.assign(this, e);
			return;
		}

		if(PathEvent.pathEventCache.has(e)) {
			Object.assign(this, PathEvent.pathEventCache.get(e)!);
			return;
		}

		let [p, method] = e.replaceAll(/(^|\/)\*+\/?$/g, '').split(':');
		if(!method) method = '*';

		// Handle special cases
		if(p === '' || p === undefined || p === '*') {
			this.module = '';
			this.path = '';
			this.fullPath = '**';
			this.name = '';
			this.methods = new ASet<Method>(p === '*' ? ['*'] : <any>method.split(''));
			this.hasGlob = true;
			PathEvent.pathEventCache.set(e, this);
			return;
		}

		let temp = p.split('/').filter(p => !!p);
		this.module = temp.splice(0, 1)[0] || '';
		this.path = temp.join('/');
		this.fullPath = `${this.module}${this.module && this.path ? '/' : ''}${this.path}`;
		this.name = temp.pop() || '';
		this.hasGlob = this.fullPath.includes('*');
		this.methods = new ASet(<any>method.split(''));
		PathEvent.pathEventCache.set(e, this);
	}

	/**
	 * Check if a filter pattern matches a target path
	 * @private
	 */
	private static matches(pattern: PathEvent, target: PathEvent): boolean {
		const methodsMatch = pattern.all || target.all || pattern.methods.intersection(target.methods).length > 0;
		if(!methodsMatch) return false;
		if(!pattern.hasGlob && !target.hasGlob) {
			const last = pattern.fullPath[target.fullPath.length];
			return pattern.fullPath.startsWith(target.fullPath) && (last == null || last == '/');
		}
		if(pattern.hasGlob) return this.pathMatchesGlob(target.fullPath, pattern.fullPath);
		return this.pathMatchesGlob(pattern.fullPath, target.fullPath);
	}

	/**
	 * Check if a path matches a glob pattern
	 * @private
	 */
	private static pathMatchesGlob(path: string, pattern: string): boolean {
		if(pattern === path) return true;
		const pathParts = path.split('/').filter(p => !!p);
		const patternParts = pattern.split('/').filter(p => !!p);

		let pathIdx = 0;
		let patternIdx = 0;
		while (patternIdx < patternParts.length && pathIdx < pathParts.length) {
			const patternPart = patternParts[patternIdx];
			if(patternPart === '**') {
				if(patternIdx === patternParts.length - 1) return true;
				while (pathIdx < pathParts.length) {
					if(PathEvent.pathMatchesGlob(pathParts.slice(pathIdx).join('/'), patternParts.slice(patternIdx + 1).join('/'))) return true;
					pathIdx++;
				}
				return false;
			} else if(patternPart === '*') {
				pathIdx++;
				patternIdx++;
			} else {
				if(patternPart !== pathParts[pathIdx]) return false;
				pathIdx++;
				patternIdx++;
			}
		}
		if(patternIdx < patternParts.length) return patternParts.slice(patternIdx).every(p => p === '**');
		return pathIdx === pathParts.length;
	}

	/**
	 * Score a path for specificity ranking (lower = more specific = higher priority)
	 * @private
	 */
	private static scoreSpecificity(path: string): number {
		if(path === '**' || path === '') return Number.MAX_SAFE_INTEGER;
		const segments = path.split('/').filter(p => !!p);
		let score = -segments.length;
		segments.forEach(seg => {
			if(seg === '**') score += 0.5;
			else if(seg === '*') score += 0.25;
		});
		return score;
	}

	/** Clear the cache of all PathEvents */
	static clearCache(): void {
		PathEvent.pathEventCache.clear();
	}

	/** Clear the permission cache */
	static clearPermissionCache(): void {
		PathEvent.permissionCache.clear();
	}

	/**
	 * Combine multiple events into one parsed object. Longest path takes precedent, but all subsequent methods are
	 * combined until a "none" is reached
	 *
	 * @param {string | PathEvent} paths Events as strings or pre-parsed
	 * @return {PathEvent} Final combined permission
	 */
	static combine(...paths: (string | PathEvent)[]): PathEvent {
		const parsed = paths.map(p => p instanceof PathEvent ? p : new PathEvent(p));
		const sorted = parsed.toSorted((p1, p2) => {
			const score1 = PathEvent.scoreSpecificity(p1.fullPath);
			const score2 = PathEvent.scoreSpecificity(p2.fullPath);
			return score1 - score2;
		});
		let result: PathEvent | null = null;
		for (const p of sorted) {
			if(!result) {
				result = p;
			} else {
				if(result.fullPath.startsWith(p.fullPath)) {
					if(p.none) break;
					result.methods = new ASet([...result.methods, ...p.methods]);
				}
			}
		}
		return result || new PathEvent('');
	}

	/**
	 * Filter a set of paths based on the target
	 *
	 * @param {string | PathEvent | (string | PathEvent)[]} target Array of events that will filtered
	 * @param filter {...PathEvent} Must contain one of
	 * @return {PathEvent[]} Filtered results
	 */
	static filter(target: string | PathEvent | (string | PathEvent)[], ...filter: (string | PathEvent)[]): PathEvent[] {
		const parsedTarget = makeArray(target).map(pe => pe instanceof PathEvent ? pe : new PathEvent(pe));
		const parsedFilter = makeArray(filter).map(pe => pe instanceof PathEvent ? pe : new PathEvent(pe));
		return parsedTarget.filter(t => !!parsedFilter.find(r => PathEvent.matches(r, t)));
	}

	/**
	 * Squash 2 sets of paths & return true if any overlap is found
	 *
	 * @param {string | PathEvent | (string | PathEvent)[]} target Array of Events as strings or pre-parsed
	 * @param has Target must have at least one of these path
	 * @return {boolean} Whether there is any overlap
	 */
	static has(target: string | PathEvent | (string | PathEvent)[], ...has: (string | PathEvent)[]): boolean {
		const parsedTarget = makeArray(target).map(pe => pe instanceof PathEvent ? pe : new PathEvent(pe));
		const parsedRequired = makeArray(has).map(pe => pe instanceof PathEvent ? pe : new PathEvent(pe));
		return !!parsedRequired.find(r => !!parsedTarget.find(t => PathEvent.matches(r, t)));
	}

	/**
	 * Squash 2 sets of paths & return true if the target has all paths
	 *
	 * @param {string | PathEvent | (string | PathEvent)[]} target Array of Events as strings or pre-parsed
	 * @param has Target must have all these paths
	 * @return {boolean} Whether all are present
	 */
	static hasAll(target: string | PathEvent | (string | PathEvent)[], ...has: (string | PathEvent)[]): boolean {
		return has.filter(h => PathEvent.has(target, h)).length == has.length;
	}

	/**
	 * Same as `has` but raises an error if there is no overlap
	 *
	 * @param {string | PathEvent | (string | PathEvent)[]} target Array of Events as strings or pre-parsed
	 * @param has Target must have at least one of these path
	 */
	static hasFatal(target: string | PathEvent | (string | PathEvent)[], ...has: (string | PathEvent)[]): void {
		if(!PathEvent.has(target, ...has)) throw new PathError(`Requires one of: ${makeArray(has).join(', ')}`);
	}

	/**
	 * Same as `hasAll` but raises an error if the target is missing any paths
	 *
	 * @param {string | PathEvent | (string | PathEvent)[]} target Array of Events as strings or pre-parsed
	 * @param has Target must have all these paths
	 */
	static hasAllFatal(target: string | PathEvent | (string | PathEvent)[], ...has: (string | PathEvent)[]): void {
		if(!PathEvent.hasAll(target, ...has)) throw new PathError(`Requires all: ${makeArray(has).join(', ')}`);
	}

	/**
	 * Create event string from its components
	 *
	 * @param {string | string[]} path Event path
	 * @param {Method} methods Event method
	 * @return {string} String representation of Event
	 */
	static toString(path: string | string[], methods: Method | Method[]): string {
		let p = makeArray(path).filter(p => !!p).join('/');
		p = p?.trim().replaceAll(/\/{2,}/g, '/').replaceAll(/(^\/|\/$)/g, '');
		if(methods?.length) p += `:${makeArray(methods).map(m => m.toLowerCase()).join('')}`;
		return p;
	}

	/**
	 * Squash 2 sets of paths & return true if any overlap is found
	 *
	 * @param has Target must have at least one of these path
	 * @return {boolean} Whether there is any overlap
	 */
	has(...has: (string | PathEvent)[]): boolean {
		return PathEvent.has(this, ...has);
	}

	/**
	 * Squash 2 sets of paths & return true if the target has all paths
	 *
	 * @param has Target must have all these paths
	 * @return {boolean} Whether all are present
	 */
	hasAll(...has: (string | PathEvent)[]): boolean {
		return PathEvent.hasAll(this, ...has);
	}

	/**
	 * Same as `has` but raises an error if there is no overlap
	 *
	 * @param has Target must have at least one of these path
	 */
	hasFatal(...has: (string | PathEvent)[]): void {
		return PathEvent.hasFatal(this, ...has);
	}

	/**
	 * Same as `hasAll` but raises an error if the target is missing any paths
	 *
	 * @param has Target must have all these paths
	 */
	hasAllFatal(...has: (string | PathEvent)[]): void {
		return PathEvent.hasAllFatal(this, ...has);
	}

	/**
	 * Filter a set of paths based on this event
	 *
	 * @param {string | PathEvent | (string | PathEvent)[]} target Array of events that will filtered
	 * @return {PathEvent[]} Filtered results
	 */
	filter(target: string | PathEvent | (string | PathEvent)[]): PathEvent[] {
		return PathEvent.filter(target, this);
	}

	/**
	 * Create event string from its components
	 *
	 * @return {string} String representation of Event
	 */
	toString() {
		return PathEvent.toString(this.fullPath, this.methods);
	}
}

export type PathListener = (event: PathEvent, ...args: any[]) => any;
export type PathUnsubscribe = () => void;

export type Event = string | PathEvent;
export interface IPathEventEmitter {
	emit(event: Event, ...args: any[]): void;
	off(listener: PathListener): void;
	on(event: Event | Event[], listener: PathListener): PathUnsubscribe;
	once(event: Event | Event[], listener?: PathListener): Promise<any>;
	relayEvents(emitter: PathEventEmitter): void;
}

/**
 * Event emitter that uses paths allowing listeners to listen to different combinations of modules, paths & methods
 */
export class PathEventEmitter implements IPathEventEmitter{
	private listeners: [PathEvent, PathListener][] = [];

	constructor(public readonly prefix: string = '') { }

	emit(event: Event, ...args: any[]) {
		const parsed = event instanceof PathEvent ? event : new PathEvent(`${this.prefix}/${event}`);
		this.listeners.filter(l => PathEvent.has(l[0], parsed))
			.forEach(l => l[1](parsed, ...args));
	};

	off(listener: PathListener) {
		this.listeners = this.listeners.filter(l => l[1] != listener);
	}

	on(event: Event | Event[], listener: PathListener): PathUnsubscribe {
		makeArray(event).forEach(e => {
			let fullEvent: string;
			if(typeof e === 'string') {
				// If event starts with ':', it's a scope specifier - prepend prefix
				if(e[0] === ':' && this.prefix) {
					fullEvent = `${this.prefix}${e}`;
				} else if(this.prefix) {
					fullEvent = `${this.prefix}/${e}`;
				} else {
					fullEvent = e;
				}
			} else {
				fullEvent = e instanceof PathEvent ? PathEvent.toString(e.fullPath, e.methods) : (e as string);
			}
			this.listeners.push([
				new PathEvent(fullEvent),
				listener
			])
		});
		return () => this.off(listener);
	}

	once(event: Event | Event[], listener?: PathListener): Promise<any> {
		return new Promise(res => {
			const unsubscribe = this.on(event, (event: PathEvent, ...args: any[]) => {
				res(args.length < 2 ? args[0] : args);
				if(listener) listener(event, ...args);
				unsubscribe();
			});
		});
	}

	relayEvents(emitter: IPathEventEmitter) {
		emitter.on('**', (event, ...args) => this.emit(event, ...args));
	}
}