Add commands API (#38)

2 files changed, 158 insertions, 0 deletions

diff --git a/src/api/Commands.ts b/src/api/Commands.ts
new file mode 100644
index 0000000..3a3e88c
--- /dev/null
+++ b/src/api/Commands.ts
@@ -0,0 +1,157 @@
+import { Channel, Guild } from "discord-types/general";
+import { waitFor } from '../webpack';
+
+export function _init(cmds: Command[]) {
+    try {
+        BUILT_IN = cmds;
+        OptionalMessageOption = cmds.find(c => c.name === "shrug")!.options![0];
+        RequiredMessageOption = cmds.find(c => c.name === "me")!.options![0];
+    } catch (e) {
+        console.error("Failed to load CommandsApi");
+    }
+    return cmds;
+}
+
+export let BUILT_IN: Command[];
+export const commands = {} as Record<string, Command>;
+
+// hack for plugins being evaluated before we can grab these from webpack
+const OptPlaceholder = Symbol("OptionalMessageOption") as any as Option;
+const ReqPlaceholder = Symbol("RequiredMessageOption") as any as Option;
+/**
+ * Optional message option named "message" you can use in commands.
+ * Used in "tableflip" or "shrug"
+ * @see {@link RequiredMessageOption}
+ */
+export let OptionalMessageOption: Option = OptPlaceholder;
+/**
+ * Required message option named "message" you can use in commands.
+ * Used in "me"
+ * @see {@link OptionalMessageOption}
+ */
+export let RequiredMessageOption: Option = ReqPlaceholder;
+
+let SnowflakeUtils: any;
+waitFor("fromTimestamp", m => SnowflakeUtils = m);
+
+export function generateId() {
+    return `-${SnowflakeUtils.fromTimestamp(Date.now())}`;
+}
+
+/**
+ * Get the value of an option by name
+ * @param args Arguments array (first argument passed to execute)
+ * @param name Name of the argument
+ * @param fallbackValue Fallback value in case this option wasn't passed
+ * @returns Value
+ */
+export function findOption<T extends string | undefined>(args: Argument[], name: string, fallbackValue?: T): T extends undefined ? T : string {
+    return (args.find(a => a.name === name)?.value || fallbackValue) as any;
+}
+
+function modifyOpt(opt: Option | Command) {
+    opt.displayName ||= opt.name;
+    opt.displayDescription ||= opt.description;
+    opt.options?.forEach((opt, i, opts) => {
+        // See comment above Placeholders
+        if (opt === OptPlaceholder) opts[i] = OptionalMessageOption;
+        else if (opt === ReqPlaceholder) opts[i] = RequiredMessageOption;
+        modifyOpt(opts[i]);
+    });
+}
+
+export function registerCommand(command: Command, plugin: string) {
+    if (BUILT_IN.some(c => c.name === command.name))
+        throw new Error(`Command '${command.name}' already exists.`);
+
+    command.id ||= generateId();
+    command.applicationId ||= "-1"; // BUILT_IN;
+    command.type ||= ApplicationCommandType.CHAT_INPUT;
+    command.inputType ||= ApplicationCommandInputType.BUILT_IN_TEXT;
+    command.plugin ||= plugin;
+
+    modifyOpt(command);
+    commands[command.name] = command;
+    BUILT_IN.push(command);
+}
+
+export function unregisterCommand(name: string) {
+    const idx = BUILT_IN.findIndex(c => c.name === name);
+    if (idx === -1)
+        return false;
+
+    BUILT_IN.splice(idx, 1);
+    delete commands[name];
+}
+
+export interface CommandContext {
+    channel: Channel;
+    guild?: Guild;
+}
+
+export enum ApplicationCommandOptionType {
+    SUB_COMMAND = 1,
+    SUB_COMMAND_GROUP = 2,
+    STRING = 3,
+    INTEGER = 4,
+    BOOLEAN = 5,
+    USER = 6,
+    CHANNEL = 7,
+    ROLE = 8,
+    MENTIONABLE = 9,
+    NUMBER = 10,
+    ATTACHMENT = 11,
+}
+
+export enum ApplicationCommandInputType {
+    BUILT_IN = 0,
+    BUILT_IN_TEXT = 1,
+    BUILT_IN_INTEGRATION = 2,
+    BOT = 3,
+    PLACEHOLDER = 4,
+}
+
+export interface Option {
+    name: string;
+    displayName?: string;
+    type: ApplicationCommandOptionType;
+    description: string;
+    displayDescription?: string;
+    required?: boolean;
+    options?: Option[];
+}
+
+export enum ApplicationCommandType {
+    CHAT_INPUT = 1,
+    USER = 2,
+    MESSAGE = 3,
+}
+
+export interface CommandReturnValue {
+    content: string;
+}
+
+export interface Argument {
+    type: ApplicationCommandOptionType;
+    name: string;
+    value: string;
+    focused: undefined;
+}
+
+export interface Command {
+    id?: string;
+    applicationId?: string;
+    type?: ApplicationCommandType;
+    inputType?: ApplicationCommandInputType;
+    plugin?: string;
+
+    name: string;
+    displayName?: string;
+    description: string;
+    displayDescription?: string;
+
+    options?: Option[];
+    predicate?(ctx: CommandContext): boolean;
+
+    execute(args: Argument[], ctx: CommandContext): CommandReturnValue | void;
+}
diff --git a/src/api/index.ts b/src/api/index.ts
index 7d39b95..7c379f9 100644
--- a/src/api/index.ts
+++ b/src/api/index.ts
@@ -1,2 +1,3 @@
 export * as MessageEvents from "./MessageEvents";
 export * as Notices from "./Notices";
+export * as Commands from "./Commands";