import { getGlobalThis, randomUUID } from '@wener/utils';

export interface App {
	readonly region?: string;
	readonly zone?: string;
	readonly env?: string;
	readonly mode?: string;

	name: string;
	component: string;
	instanceId: string;
	readonly service: string;
	readonly isProduction: boolean;
	readonly isDevelopment: boolean;

	envs(): Record<string, any>;

	reset(): void;
}

class DefaultApp implements App {
	private static readonly DEFAULT_NAME = 'app';
	private static readonly DEFAULT_COMPONENT = typeof document !== 'undefined' ? 'web' : 'server';

	#region?: string;
	#zone?: string;
	#instanceId?: string;
	#name?: string;
	#component?: string;
	#mode?: string;
	#env?: string;
	#envs: Record<string, any> = {};

	toJSON() {
		return {
			region: this.region,
			zone: this.zone,
			mode: this.mode,
			env: this.env,
			name: this.name,
			component: this.component,
			instanceId: this.instanceId,
			service: this.service,
			isProduction: this.isProduction,
			isDevelopment: this.isDevelopment,
		};
	}

	envs() {
		if (typeof process === 'object' && 'env' in process) {
			return process.env;
		}
		return this.#envs;
	}

	get region() {
		return (this.#region ||= process.env.APP_REGION);
	}

	get zone() {
		return (this.#zone ||= process.env.APP_ZONE);
	}

	get mode() {
		return (this.#mode ||= process.env.NODE_ENV);
	}

	get env() {
		return (this.#mode ||= process.env.APP_ENV);
	}

	get service() {
		return `${this.name}-${this.component}`;
	}

	get name() {
		return (this.#name ||= process.env.APP_NAME || DefaultApp.DEFAULT_NAME);
	}

	set name(name: string) {
		this.#name = name;
	}

	get isProduction() {
		switch (this.mode) {
			case 'production':
			case 'prod':
			case 'prd':
				return true;
			default:
				return false;
		}
	}

	get isDevelopment() {
		switch (this.mode) {
			case 'development':
			case 'dev':
				return true;
			default:
				return false;
		}
	}

	get instanceId() {
		if (this.#instanceId) {
			return this.#instanceId;
		}

		let prefix = this.service;
		let hostname = '';
		let pid = 0;
		const globalThis: any = getGlobalThis();
		if (typeof globalThis.os === 'object' && 'hostname' in globalThis.os) {
			hostname = globalThis.os
				.hostname()
				.toLowerCase()
				.replaceAll(/[^-a-z\d]/g, '-');
		}

		if (typeof globalThis.process === 'object' && 'pid' in globalThis.process) {
			pid = globalThis.process.pid;
		}

		prefix = hostname.startsWith(prefix) ? hostname : `${prefix}-${pid}`;
		return (this.#instanceId ||= process.env.APP_ID || `${prefix}-${randomUUID()}`.slice(0, 36).replace(/-$/, ''));
	}

	set instanceId(v) {
		this.#instanceId = v;
	}

	get component() {
		return (this.#component ||= process.env.APP_COMPONENT || DefaultApp.DEFAULT_COMPONENT);
	}

	set component(v) {
		this.#component = v;
	}

	/**
	 * If env changed, we should reset what we already init
	 */
	reset() {
		this.#region = undefined;
		this.#zone = undefined;
		this.#component = undefined;
		this.#name = undefined;
		this.#instanceId = undefined;
		this.#mode = undefined;
		this.#env = undefined;
	}
}

export const App = new DefaultApp();