import { type DiscordAPIEvent, Expectation, HandlerType, Intent, type ClientConfig } from '../types/common';
import { Message, type DiscordMessage } from '../types/message';
import { exists, isNil } from '../utils/index';
import { API } from './api';
import { EventBus, type Emitter } from './bus';
import { Channels } from './caches/channels';
import { Guilds } from './caches/guilds';
import { Messages } from './caches/messages';
import { Users } from './caches/users';
import { Gateway } from './connectors/gateway';
import { hydrate, hydrator, type Hydrateable, type Hydrated } from './hydrator';
import { Processor } from './processor';

export class Client {
    readonly config: Readonly<Required<ClientConfig>>;
    // Internal services
    protected bus: Emitter;
    protected api: API;
    protected processor: Processor;
    protected gateway: Gateway;
    // Caches
    readonly caches: {
        readonly guilds: Guilds;
        readonly users: Users;
        readonly messages: Messages;
        readonly channels: Channels;
    };

    constructor(config: ClientConfig) {
        // Validate the configuration
        Client.validateConfig(config);
        // Save the configuration
        this.config = Object.freeze({
            token: config.token,
            application_id: config.application_id,
            intents: config.intents ?? [Intent.DEFAULT],
            prefix: config.prefix ?? '!',
        });
        // Initialize internal services
        this.bus = EventBus;
        this.api = new API(this);
        this.processor = new Processor(this, this.api, this.bus);
        this.gateway = new Gateway(this, this.processor, this.api, this.bus);
        // Initialize caches
        this.caches = {
            guilds: new Guilds(this.api, this.processor),
            users: new Users(this.api, this.processor),
            messages: new Messages(this.api, this.processor),
            channels: new Channels(this.api, this.processor),
        };
    }

    private static validateConfig(config: ClientConfig) {
        if (isNil(config.token)) {
            throw new Error('Token is required');
        }

        if (isNil(config.application_id)) {
            throw new Error('Application ID is required');
        }

        if (exists(config.prefix) && typeof config.prefix !== 'string') {
            throw new Error('Prefix must be a string');
        }

        if (exists(config.intents)) {
            if (!Array.isArray(config.intents)) {
                throw new Error('Intents must be an array');
            }

            for (const intent of config.intents) {
                if (!Intent[intent]) {
                    throw new Error(`Invalid intent: ${intent}`);
                }
            }
        }
    }

    get self() {
        return this.gateway.user;
    }

    get chatCommands() {
        return this.processor[HandlerType.ChatCommands];
    }

    get applicationCommands() {
        return this.processor[HandlerType.ApplicationCommands];
    }

    get interactions() {
        return this.processor[HandlerType.Interactions];
    }

    get events() {
        return this.processor[HandlerType.Events];
    }

    /**
     * Hydrates a given data object based on the provided expectations.
     *
     * @template T - The type of the data object to be hydrated. Must extend `Hydrateable`.
     * @template K - An array of `Expectation` types that specify what properties should be hydrated.
     *
     * @param data - The data object to be hydrated. Can be of type `Context` or `Message`.
     * @param expectations - An array of expectations that specify what properties should be hydrated.
     *
     * @returns A promise that resolves to the hydrated data object.
     *
     * @throws Will throw an error if an expectation cannot be resolved.
     */
    hydrate = async <T extends Hydrateable | Hydrated<Hydrateable, Array<Expectation>>, K extends Array<Expectation>>(
        data: T,
        expectations: K,
    ) => {
        return hydrate<T, K>(data, expectations, this, this.api);
    };

    /**
     * A wrapper function that attempts to hydrate a given data object and returns a type guard function.
     *
     * @template T - The type of the data object to be hydrated. Must extend `Hydrateable`.
     * @template K - An array of `Expectation` types that specify what properties should be hydrated.
     *
     * @param data - The data object to be hydrated. Can be of type `Context` or `Message`.
     * @param expectations - An array of expectations that specify what properties should be hydrated.
     *
     * @returns A promise that resolves to a type guard function. The type guard function returns `true` if the data object was successfully hydrated, otherwise `false`.
     */
    hydrator = async <T extends Hydrateable, K extends Expectation[]>(data: T, expectations: K) => {
        return hydrator<T, K>(data, expectations, this, this.api);
    };

    sendMessage = async (channel_id: string, message: Message | string) => {
        if (typeof message === 'string') {
            message = new Message().setContent(message);
        }

        return Message.fromDiscord(
            await this.api.post<DiscordMessage>(`/channels/${channel_id}/messages`, message.toJSON()),
        );
    };

    /**
     * Makes a raw HTTP request to the Discord API.
     * @param method HTTP method to use for the request (GET, POST, PUT, DELETE).
     * @param endpoint The API endpoint to request; can start with a slash or be a full URL.
     * @param body Optional body to send with the request, typically used for POST or PUT requests.
     * @returns A promise that resolves to the response data of type T.
     */
    rawRequest = async <T = Record<string, any>>(
        method: 'GET' | 'POST' | 'PUT' | 'DELETE',
        endpoint: string,
        body?: Record<string, any>,
    ): Promise<T> => {
        return this.api.request<T>(method, endpoint, body);
    };

    // chatCommands = {
    //     register: (name: string | string[], handler: Handler) => this.processor.chat_commands.register(name, handler),
    //     unregister: (name: string | string[]) => this.processor.chat_commands.unregister(name),
    //     has: (name: string) => this.processor.chat_commands.has(name)
    // }

    // applicationCommands = {
    //     register: (name: string, type: ApplicationCommandType, handler: Handler) => this.processor.application_commands.register(name, type, handler),
    //     unregister: (name: string) => this.processor.application_commands.unregister(name),
    //     has: (name: string) => this.processor.application_commands.has(name)
    // }

    on = (event: DiscordAPIEvent, handler: (...args: any[]) => void) => this.bus.on(event, handler);

    once = (event: DiscordAPIEvent, handler: (...args: any[]) => void) => this.bus.once(event, handler);

    off = (event: DiscordAPIEvent, handler: (...args: any[]) => void) => this.bus.off(event, handler);

    connect = () => this.gateway.connect();
}