import type { Arg, Context, ParseType, Visibility } from "../types/handler";
import * as Files from "./utils/readFile"
import type { ApplicationCommandOptionData, Awaitable, Client, CommandInteraction, Message } from "discord.js";
import type { possibleOutput } from "../types/handler"
import { Ok, Result, None, Some } from "ts-results";
import type * as Utils from "./utils/preprocessors/args";
import { CtxHandler } from "./utils/ctxHandler";
import { DefaultLogger,  Logger } from "./logger";


/**
 * @class
 */
export class Handler {
    private wrapper: Wrapper;
    private logger : Logger<unknown>; 
    /**
     * @constructor
     * @param {Wrapper} wrapper Some data that is required to run sern handler 
     */
    constructor(
        wrapper: Wrapper,
        logger? : Logger<unknown>,
    ) {
        this.wrapper = wrapper;
        logger === undefined 
        ? this.logger = new DefaultLogger()
        : this.logger = logger;

        this.logger.clear();
        

        this.wrapper.client
            .on("ready", async () => {
                if (this.wrapper.init !== undefined) this.wrapper.init(this);
                await Files.registerModules(this);
            })

            .on("messageCreate", async message => {
                if (CtxHandler.isBot(message) || !CtxHandler.hasPrefix(message, this.prefix)) return;
                const tryFmt = CtxHandler.fmt(message, this.prefix)
                const commandName = tryFmt.shift()!;
                const module = Files.Commands.get(commandName) ?? Files.Alias.get(commandName)
                if (module === undefined) {
                    message.channel.send("Unknown legacy command")
                    return;
                }
                const cmdResult = (await this.commandResult(module?.mod, message, tryFmt.join(" ")))
                if (cmdResult === undefined) return;

                message.channel.send(cmdResult)

            })

            .on("interactionCreate", async interaction => {
                if (!interaction.isCommand()) return;
                const module = Files.Commands.get(interaction.commandName);
                const res = await this.interactionResult(module, interaction);
                if (res === undefined) return;
                await interaction.reply(res);
            })
    }

    private async interactionResult(
        module: { mod: Module<unknown>, options: ApplicationCommandOptionData[] } | undefined,
        interaction: CommandInteraction): Promise<possibleOutput | undefined> {

        if (module === undefined) return "Unknown slash command!";
        const name = Array.from(Files.Commands.keys()).find(it => it === interaction.commandName);
        if(name === undefined) return `Could not find ${interaction.commandName} command!`;
        (await this.client.guilds.fetch(this.privateServerId))
            .commands
            .create({
                name,
                description: module.mod.desc,
                options: module.options
            });

        if (module.mod.type < CommandType.SLASH) return "This is not a slash command";
        const context = { message: None, interaction: Some(interaction) }
        const parsedArgs = module.mod.parse?.(context, ["slash", interaction.options]) ?? Ok("");
        if (parsedArgs.err) return parsedArgs.val;
        const fn = await module.mod.delegate(context, parsedArgs);
        return fn?.val;
    }

    private emitEvent() {

    }

    private async commandResult(module: Module<unknown> | undefined, message: Message, args: string): Promise<possibleOutput | undefined> {
        if (module === undefined) return "Unknown legacy command";
        if (module.visibility === "private" && message.guildId !== this.privateServerId) {
            return "This command is not availible in this guild!"
        }
        if (module.type === CommandType.SLASH) return `This may be a slash command and not a legacy command`
        const context = { message: Some(message), interaction: None }
        const parsedArgs = module.parse?.(context, ["text", args]) ?? Ok("");
        if (parsedArgs.err) return parsedArgs.val;
        const fn = await module.delegate(context, parsedArgs)
        return fn?.val
    }
    /**
     * @readonly
     * @returns {string} prefix used for legacy commands
     */
    get prefix(): string {
        return this.wrapper.prefix;
    }
    /**
    * @readonly
    * @returns {string} directory of your commands folder
    */
    get commandDir(): string {
        return this.wrapper.commands;
    }
    /**
     * @readonly
     * @returns {Client<boolean>} discord.js client
     */
    get client(): Client<boolean> {
        return this.wrapper.client
    }
    /**
     * @readonly
     * @returns {string} private server id for testing or personal use
     */
    get privateServerId(): string {
        return this.wrapper.privateServerId;
    }


}
/**
 * An object to be passed into Sern.Handler constructor. 
 * ```ts
 * new Sern.Handler({
 *   client,       // Discord.js client instance          
 *   prefix : "!", // an example prefix
 *   commands: "",  //commands directory
 *   init : () => console.log("Bot is ready") // function called on ready
 *   privateServerId : "" // a server id that can be used for private or test server
 * })
 * ```
 */
export interface Wrapper {
    readonly client: Client,
    readonly prefix: string,
    readonly commands: string
    init?: (handler: Handler) => void,
    readonly privateServerId: string,
}
/**
 * @interface - Modules that are used in command files
 */
export interface Module<T = void> {
    alias: string[],
    desc: string,
    visibility: Visibility,
    type: CommandType,
    delegate: (eventParams: Context, args: Ok<T>) => Awaitable<Result<possibleOutput, string> | void>
    parse?: (ctx: Context, args: Arg) => Utils.ArgType<T>
}
/**
 * @enum { number };
 */
export enum CommandType {
    TEXT = 1,
    SLASH = 2,
}