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

import { ApplicationCommandOptionTypes, DiscordApplicationCommandOption, type CreateApplicationCommand, type DiscordInteractionDataOption } from '@discordeno/types'
import type { InteractionData } from '..'
import type { SLASH_COMMANDS } from './slash_commands'

// 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 DiscordApplicationCommandOption[] ? (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 DiscordApplicationCommandOption[]> = {
  [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 = Record<string, never>> = (args: Args) => Promise<void> | void



// Get subcommand or subcommand group by name
type GetSubcommandOrGroup<Options, Name> = Options extends readonly DiscordApplicationCommandOption[]
  ? Options[number] extends infer O
    ? O extends { name: Name; type: ApplicationCommandOptionTypes.SubCommand | ApplicationCommandOptionTypes.SubCommandGroup }
      ? O
      : never
    : never
  : never

// Check if all options are subcommands or subcommand groups
type HasOnlySubcommands<Options extends readonly DiscordApplicationCommandOption[]> = Options[number] extends { type: ApplicationCommandOptionTypes.SubCommand | ApplicationCommandOptionTypes.SubCommandGroup } ? true : false

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

// Type to extract subcommand handlers (recursive for groups)
export type SubcommandHandlers<Options extends readonly DiscordApplicationCommandOption[]> = {
  [K in SubcommandNames<Options>]: GetSubcommandOrGroup<Options, K> extends { type: infer T; options?: infer SubOpts }
    ? T extends ApplicationCommandOptionTypes.SubCommandGroup
      ? SubOpts extends readonly DiscordApplicationCommandOption[]
        ? SubcommandHandlers<SubOpts>
        : never
      : T extends ApplicationCommandOptionTypes.SubCommand
      ? SubOpts extends readonly DiscordApplicationCommandOption[]
        ? HandlerFunction<ExtractArgs<SubOpts>>
        : HandlerFunction<Record<string, never>>
      : never
    : never
}

// 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 CreateApplicationCommand[]> = {
  [Name in T[number]['name']]: GetCommand<T, Name> extends { options?: infer Options }
    ? Options extends readonly DiscordApplicationCommandOption[]
      ? HasOnlySubcommands<Options> extends true
        ? SubcommandHandlers<Options>
        : HandlerFunction<ExtractArgs<Options>>
      : HandlerFunction<Record<string, never>>
    : HandlerFunction<Record<string, never>>
}

// Type representing the possible output of ExtractCommands
export type CommandHandler = HandlerFunction<any> | CommandHandlerMap
export type CommandHandlerMap = {
  [key: string]: CommandHandler
}

// 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. there is sort of a hack here
// so the actual type we need to parse comes from the parsing of DiscordApplicationCommandOption
// but this is parsing from the DiscordInteractionDataOption type, which is just the generic data response.
// technically, at runtime, with the SLASH_COMMANDS object, it's possible to validate this struct, and produce a better type than any
// but that is... a lot of work, so we are just going to do this for now and leave validation for another day.
function parseOptions<T extends DiscordInteractionDataOption[]>(options?: T): 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
}

// Unified recursive handler for commands, subcommands, and subcommand groups
async function handleCommands(
  handler: CommandHandler,
  options: DiscordInteractionDataOption[] | undefined,
  notFoundHandler: HandlerFunction<{path?: string}>
): Promise<void> {
  // If handler is a function, execute it with parsed options
  if (typeof handler === 'function') {
    const args = parseOptions(options)
    await handler(args)
    return
  }

  // Handler is a map of subcommands/groups
  const subcommand = options?.find(
    (opt) => opt.type === ApplicationCommandOptionTypes.SubCommand || opt.type === ApplicationCommandOptionTypes.SubCommandGroup
  )

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

  const subHandler = handler[subcommand.name]
  if (!subHandler) {
    await notFoundHandler({})
    return
  }

  // Recursively handle the subcommand/group
  await handleCommands(subHandler, subcommand.options, notFoundHandler)
}

// Helper function to create command handlers with type safety
export function createCommandHandler<T extends readonly CreateApplicationCommand[]>({
  handler,
  notFoundHandler,
}: {
  commands: T,
  handler: ExtractCommands<T>
  notFoundHandler: HandlerFunction<{path?: string}>
}) {
  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
    }
    // Use unified handler for all command types
    await handleCommands(commandHandler, data.options, notFoundHandler)
  }
}