wynn/ts/src/discord/botevent/command_parser.ts

import { ApplicationCommandOptionTypes, CreateApplicationCommand, DiscordInteractionDataOption} from "@discordeno/types";
import { SLASH_COMMANDS } from "./slash_commands";
import { InteractionData } from "..";

// Map option types to their TypeScript types
type OptionTypeMap = {
  [ApplicationCommandOptionTypes.String]: string;
  [ApplicationCommandOptionTypes.Integer]: number;
  [ApplicationCommandOptionTypes.Boolean]: boolean;
  [ApplicationCommandOptionTypes.User]: string; // user ID
  [ApplicationCommandOptionTypes.Channel]: string; // channel ID
  [ApplicationCommandOptionTypes.Role]: string; // role ID
  [ApplicationCommandOptionTypes.Number]: number;
  [ApplicationCommandOptionTypes.Mentionable]: string; // ID
  [ApplicationCommandOptionTypes.Attachment]: string; // attachment ID
};

// Helper type to get option by name
type GetOption<Options, Name> = Options extends readonly any[]
  ? Options[number] extends infer O
    ? O extends { name: Name }
      ? O
      : never
    : never
  : never;

// Extract the argument types from command options
export type ExtractArgs<Options extends readonly any[]> = {
  [K in Options[number]['name']]: GetOption<Options, K> extends { type: infer T; required?: infer R }
    ? T extends keyof OptionTypeMap
      ? R extends true
        ? OptionTypeMap[T]
        : OptionTypeMap[T] | undefined
      : never
    : never;
};

// Handler function type that accepts typed arguments
type HandlerFunction<Args = {}> = (args: Args) => Promise<void> | void;

// Get subcommand by name
type GetSubcommand<Options, Name> = Options extends readonly any[]
  ? Options[number] extends infer O
    ? O extends { name: Name; type: ApplicationCommandOptionTypes.SubCommand }
      ? O
      : never
    : never
  : never;

// Check if all options are subcommands
type HasOnlySubcommands<Options extends readonly any[]> = 
  Options[number] extends { type: ApplicationCommandOptionTypes.SubCommand }
    ? true
    : false;

// Extract subcommand names from options
type SubcommandNames<Options extends readonly any[]> = 
  Options[number] extends { name: infer N; type: ApplicationCommandOptionTypes.SubCommand }
    ? N extends string
      ? N
      : never
    : never;

// Type to extract subcommand handlers
export type SubcommandHandlers<Options extends readonly any[]> = {
  [K in SubcommandNames<Options>]: GetSubcommand<Options, K> extends { options?: infer SubOpts }
    ? SubOpts extends readonly any[]
      ? HandlerFunction<ExtractArgs<SubOpts>>
      : HandlerFunction<{}>
    : HandlerFunction<{}>
};

// Get command by name from array
type GetCommand<Commands extends readonly any[], Name> = Commands[number] extends infer C
  ? C extends { name: Name }
    ? C
    : never
  : never;

// Main type to extract command handlers from slash commands
export type ExtractCommands<T extends readonly any[]> = {
  [Name in T[number]['name']]: GetCommand<T, Name> extends { options?: infer Options }
    ? Options extends readonly any[]
      ? HasOnlySubcommands<Options> extends true
        ? SubcommandHandlers<Options>
        : HandlerFunction<ExtractArgs<Options>>
      : HandlerFunction<{}>
    : HandlerFunction<{}>
};

// The actual command handler type based on SLASH_COMMANDS
export type CommandHandlers = ExtractCommands<typeof SLASH_COMMANDS>;

// Helper function to parse option values from interaction data
function parseOptions(options?: DiscordInteractionDataOption[]): Record<string, any> {
  if (!options) return {};

  const args: Record<string, any> = {};

  for (const option of options) {
    if (option.type === ApplicationCommandOptionTypes.SubCommand ||
        option.type === ApplicationCommandOptionTypes.SubCommandGroup) {
      continue;
    }

    args[option.name] = option.value;
  }

  return args;
}

// Helper function to create command handlers with type safety
export function createCommandHandler<T extends readonly CreateApplicationCommand[]>(
  {handler, notFoundHandler}:{
  handler: ExtractCommands<T>
  notFoundHandler: HandlerFunction<{}>
}) {
  return async (data: InteractionData): Promise<void> => {
    if (!data || !data.name) {
      await notFoundHandler({});
      return;
    }

    const commandName = data.name as keyof typeof handler;
    const commandHandler = handler[commandName];

    if (!commandHandler) {
      await notFoundHandler({});
      return;
    }

    // Check if it's a direct command or has subcommands
    if (typeof commandHandler === 'function') {
      // Parse arguments from top-level options
      const args = parseOptions(data.options);
      await commandHandler(args);
    } else {
      // Handle subcommands
      const subcommand = data.options?.find(
        opt => opt.type === ApplicationCommandOptionTypes.SubCommand ||
              opt.type === ApplicationCommandOptionTypes.SubCommandGroup
      );

      if (!subcommand) {
        await notFoundHandler({});
        return;
      }

      const subHandler = commandHandler[subcommand.name as keyof typeof commandHandler];
      if (!subHandler || typeof subHandler !== 'function') {
        await notFoundHandler({});
        return;
      }

      // Parse arguments from subcommand options
      const args = parseOptions(subcommand.options);
      await (subHandler as HandlerFunction<any>)(args);
    }
  }
}