/**
 * @license
 * Copyright 2022-2026 Matter.js Authors
 * SPDX-License-Identifier: Apache-2.0
 */

import { ServiceProvider } from "#environment/ServiceProvider.js";
import { SharedEnvironmentServices } from "#environment/SharedEnvironmentServices.js";
import { SharedServicesManager } from "#environment/SharedServicesManager.js";
import { Diagnostic } from "#log/Diagnostic.js";
import { LogFormat } from "#log/LogFormat.js";
import { InternalError } from "#MatterError.js";
import { Instant } from "#time/TimeUnit.js";
import { Lifetime } from "#util/Lifetime.js";
import { MaybePromise } from "#util/Promises.js";
import { DiagnosticSource } from "../log/DiagnosticSource.js";
import { Logger } from "../log/Logger.js";
import "../polyfills/disposable.js";
import { Time } from "../time/Time.js";
import { Destructable, UnsupportedDependencyError } from "../util/Lifecycle.js";
import { Observable } from "../util/Observable.js";
import { Environmental } from "./Environmental.js";
import { RuntimeService } from "./RuntimeService.js";
import { VariableService } from "./VariableService.js";

const logger = Logger.get("Environment");

/**
 * Access to general platform-dependent features.
 *
 * The following variables are defined by this class:
 * * `log.level` - Log level to use {@link Logger.LEVEL}
 * * `log.format` - Log format to use {@link Logger.FORMAT}
 * * `log.stack.limit` - Stack trace limit, see https://nodejs.org/api/errors.html#errorstacktracelimit
 * * `mdns.networkInterface` - Network interface to use for MDNS broadcasts and scanning, default are all available interfaces
 * * `mdns.ipv4` - Also announce/scan on IPv4 interfaces
 * * `network.interface` - Map of interface names to types, expected to be defined as object with name as key and of `{type: string|number}` objects with types: 1=Wifi, 2=Ethernet, 3=Cellular, 4=Thread (strings or numbers can be used). Can also be provided via env or cli like `MATTER_NETWORK_INTERFACE_ETH0_TYPE=Ethernet`
 *
 * The environment supports reference-counted service sharing through shared service instances. Create
 * a shared instance using {@link asDependent} to access services with automatic lifecycle tracking at
 * the root environment. Shared services enable safe sharing across multiple consumers - services are
 * protected from premature closure and only cleaned up when all consumers have released them.
 *
 * Services can be accessed directly via {@link get} for immediate use, or through {@link SharedEnvironmentServices}
 * for tracked access at the root level. Direct access means services close immediately when requested.
 * Shared access means services are registered at root and only close when all consumers have released them.
 *
 * When services are deleted or closed without shared tracking, the service is blocked locally and does
 * not inherit from parent environments. When accessed through shared instances, the service is managed
 * at the root environment and protected as long as any consumer is using it.
 *
 * TODO - could remove global singletons by moving here
 */
export class Environment implements ServiceProvider, Lifetime.Owner {
    #services?: Map<Environmental.ServiceType, Environmental.Service | null>;
    #name: string;
    #parent?: Environment;
    #lifetime: Lifetime;
    #added = Observable<[type: Environmental.ServiceType, instance: {}]>();
    #deleted = Observable<[type: Environmental.ServiceType, instance: {}]>();
    #serviceEvents = new Map<Environmental.ServiceType, Environmental.ServiceEvents<any>>();

    constructor(name: string, parent?: Environment) {
        this.#name = name;
        this.#parent = parent;
        this.#lifetime = (parent ?? Lifetime.process).join(Diagnostic.strong(name), "environment");
    }

    join(...name: unknown[]) {
        return this.#lifetime?.join(...name);
    }

    /**
     * Create a shared service instance for reference-counted service access at root.
     *
     * Shared instances track which services they use and enable safe sharing across multiple
     * consumers. Services are automatically protected from premature closure and only
     * cleaned up when all consumers have released them, e.g. by calling close().
     *
     * All shared instances operate at the root environment for centralized lifecycle
     * management, regardless of which environment in the hierarchy creates them.
     *
     * @returns A new shared service instance for accessing services with lifecycle tracking
     */
    asDependent(): SharedEnvironmentServices {
        const dependent = new SharedEnvironmentServices(this.root);
        this.get(SharedServicesManager).add(dependent);
        return dependent;
    }

    /**
     * Determine if an environmental service is available.
     */
    has(type: Environmental.ServiceType): boolean {
        const instance = this.#services?.get(type);

        if (instance === null) {
            return false;
        }

        return instance !== undefined || (this.#parent?.has(type) ?? false);
    }

    /**
     * Determine if an environmental services is owned by this environment (not an ancestor).
     */
    owns(type: Environmental.ServiceType): boolean {
        return !!this.#services?.get(type);
    }

    /**
     * Access an environmental service.
     */
    get<T extends object>(type: Environmental.ServiceType<T>): T {
        const mine = this.#services?.get(type);

        if (mine !== undefined && mine !== null) {
            return mine as T;
        }

        // When null then we do not have it and also do not want to inherit from parent
        if (mine === undefined) {
            const instance = this.#parent?.maybeGet(type);
            if (instance !== undefined && instance !== null) {
                // Parent has it, use it
                return instance;
            }
        }

        // ... otherwise try to create it. The create method must install it in the environment if needed
        if ((type as Environmental.Factory<T>)[Environmental.create]) {
            const instance = (type as any)[Environmental.create](this) as T;
            if (!(instance instanceof type)) {
                throw new InternalError(`Service creation did not produce instance of ${type.name}`);
            }

            return instance;
        }

        throw new UnsupportedDependencyError(`Required dependency ${type.name}`, "is not available");
    }

    /**
     * Access an environmental service that may not exist.
     */
    maybeGet<T extends object>(type: Environmental.ServiceType<T>): T | undefined {
        if (this.has(type)) {
            return this.get(type);
        }
    }

    /**
     * Remove an environmental service and block further inheritance.
     *
     * If any consumer is currently using the service, deletion is deferred until all
     * consumers have released it. Services accessed via {@link SharedEnvironmentServices}
     * are protected from premature removal.
     */
    delete(type: Environmental.ServiceType, instance?: any) {
        const localInstance = this.#services?.get(type);

        if (this.get(SharedServicesManager).has(type)) {
            return;
        }

        // Remove instance and replace by null to prevent inheritance from parent
        this.#services?.set(type, null);

        if (localInstance === undefined || localInstance === null) {
            return;
        }
        if (instance !== undefined && localInstance !== instance) {
            return;
        }

        this.#deleted.emit(type, localInstance);

        const serviceEvents = this.#serviceEvents.get(type);
        if (serviceEvents) {
            serviceEvents.deleted.emit(localInstance);
        }
    }

    /**
     * Remove and close an environmental service.
     *
     * Calls the service's close method if present, then removes it from the environment.
     * If any consumer is currently using the service, closure is deferred until all
     * consumers have released it.
     */
    close<T extends object>(
        type: Environmental.ServiceType<T>,
    ): T extends { close: () => MaybePromise<void> } ? MaybePromise<void> : void {
        const instance = this.maybeGet(type);
        this.delete(type, instance);
        if (instance !== undefined) {
            if (this.get(SharedServicesManager).has(type)) {
                // still in use
                return;
            }

            return (instance as Partial<Destructable>).close?.() as T extends { close: () => MaybePromise<void> }
                ? MaybePromise<void>
                : void;
        }
    }

    /**
     * Access an environmental service, waiting for any async initialization to complete.
     */
    async load<T extends Environmental.Service>(type: Environmental.Factory<T>): Promise<T> {
        const instance = this.get(type);
        await instance.construction;
        return instance;
    }

    /**
     * Install a preinitialized version of an environmental service.
     */
    set<T extends {}>(type: Environmental.ServiceType<T>, instance: T) {
        if (!this.#services) {
            this.#services = new Map();
        }
        // Services installed via set() don't have a participant mode yet - it will be determined on first access
        this.#services.set(type, instance as Environmental.Service);
        this.#added.emit(type, instance);
        const serviceEvents = this.#serviceEvents.get(type);
        if (serviceEvents) {
            serviceEvents.added.emit(instance);
        }
    }

    /**
     * Name of the environment.
     */
    get name() {
        return this.#name;
    }

    /**
     * Get the root environment in the hierarchy.
     *
     * Recursively traverses parent links to find the topmost environment with no parent.
     * Used internally to ensure certain services (like DependentsManager) are installed
     * at a single, consistent location for the entire environment tree.
     */
    get root(): Environment {
        return this.#parent?.root ?? this;
    }

    /**
     * Emits on service add.
     *
     * Currently only emits for services owned directly by this environment.
     */
    get added() {
        return this.#added;
    }

    /**
     * Emits on service delete.
     *
     * Currently only emits for services owned directly by this environment.
     */
    get deleted() {
        return this.#deleted;
    }

    /**
     * Obtain an object with events that trigger when a specific service is added or deleted.
     *
     * This is a more convenient way to observe a specific service than {@link added} and {@link deleted}.
     */
    eventsFor<T extends Environmental.ServiceType>(type: T) {
        let events = this.#serviceEvents.get(type);
        if (events === undefined) {
            events = {
                added: Observable(),
                deleted: Observable(),
            };
            this.#serviceEvents.set(type, events);
        }
        return events as Environmental.ServiceEvents<T>;
    }

    /**
     * Apply functions to a specific service type automatically.
     *
     * The environment invokes {@link added} immediately if the service is currently present.  It then invokes
     * {@link added} in the future if the service is added or replaced and/or {@link deleted} if the service is replaced
     * or deleted.
     */
    applyTo<T extends object>(
        type: Environmental.ServiceType<T>,
        added?: (env: Environment, service: T) => MaybePromise<void>,
        deleted?: (env: Environment, service: T) => MaybePromise<void>,
    ) {
        const events = this.eventsFor(type);

        if (added) {
            const existing = this.maybeGet(type);

            if (existing) {
                added(this, existing);
            }

            events.added.on(service =>
                this.runtime.add(async () => {
                    using _adding = this.join(`adding ${type.name}`);
                    await added(this, service);
                }),
            );
        }

        if (deleted) {
            events.deleted.on(service =>
                this.runtime.add(async () => {
                    using _deleting = this.join(`adding ${type.name}`);
                    await deleted(this, service);
                }),
            );
        }
    }

    /**
     * The default environment.
     *
     * Currently only emits for services owned directly by this environment.
     */
    static get default() {
        return global;
    }

    /**
     * Set the default environment.
     */
    static set default(env: Environment) {
        global[Symbol.dispose]();

        global = env;

        env.vars.use(() => {
            Logger.level = env.vars.get("log.level", Logger.level);
            Logger.format = env.vars.get("log.format", Logger.format);

            const stackLimit = global.vars.number("log.stack.limit");
            if (stackLimit !== undefined) {
                (Error as { stackTraceLimit?: number }).stackTraceLimit = stackLimit;
            }
        });
    }

    /**
     * Shortcut for accessing {@link VariableService.vars}.
     */
    get vars() {
        return this.get(VariableService);
    }

    /**
     * Shortcut for accessing {@link RuntimeService}.
     */
    get runtime() {
        return this.get(RuntimeService);
    }

    /**
     * Display tasks that supply diagnostics.
     */
    diagnose() {
        Time.getTimer("diagnostics", Instant, () => {
            try {
                logger.notice("Diagnostics follow", DiagnosticSource);
            } catch (e) {
                logger.error(`Unhandled error gathering diagnostics:`, e);
            }
        }).start();
    }

    protected loadVariables(): Record<string, any> {
        return {};
    }

    [Symbol.dispose]() {
        // Currently this is just a method for terminating our lifetime
        this.#lifetime[Symbol.dispose]();
    }
}

let global = new Environment("default");

if (typeof MatterHooks !== "undefined") {
    MatterHooks.generateDiagnostics = () =>
        (LogFormat.formats[Logger.format] ?? LogFormat.formats.ansi)(DiagnosticSource);
}