From 85cb06bbe4b79f6e118e3875adffe51f708912fb Mon Sep 17 00:00:00 2001
From: Shigma <1700011071@pku.edu.cn>
Date: Tue, 18 Feb 2020 09:56:52 +0800
Subject: [PATCH] feat(plugin-common): support functional usage

---
 packages/koishi-core/src/command.ts |  5 +++--
 packages/plugin-common/src/help.ts  | 21 +++++++++++----------
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/packages/koishi-core/src/command.ts b/packages/koishi-core/src/command.ts
index a139ee5009..f4b0b6b888 100644
--- a/packages/koishi-core/src/command.ts
+++ b/packages/koishi-core/src/command.ts
@@ -23,6 +23,7 @@ export interface ParsedCommandLine extends Partial<ParsedLine> {
 }
 
 export type UserType <T> = T | ((user: UserData) => T)
+export type CommandUsage = string | ((this: Command, meta: Meta) => string | Promise<string>)
 
 export interface CommandConfig {
   /** disallow unknown options */
@@ -80,7 +81,7 @@ export class Command {
 
   _aliases: string[] = []
   _options: CommandOption[] = []
-  _usage?: string
+  _usage?: CommandUsage
   _examples: string[] = []
   _shortcuts: Record<string, ShortcutConfig> = {}
   _userFields = new Set<UserField>()
@@ -185,7 +186,7 @@ export class Command {
     return this
   }
 
-  usage (text: string) {
+  usage (text: CommandUsage) {
     this._usage = text
     return this
   }
diff --git a/packages/plugin-common/src/help.ts b/packages/plugin-common/src/help.ts
index 6ac09ea7aa..d47f66a5ed 100644
--- a/packages/plugin-common/src/help.ts
+++ b/packages/plugin-common/src/help.ts
@@ -69,15 +69,15 @@ export const GLOBAL_HELP_EPILOGUE = [
   '输入“帮助+指令名”查看特定指令的语法和使用示例。',
 ].join('\n')
 
-function showGlobalHelp (context: Context, meta: Meta<'message'>, options: any) {
+function showGlobalHelp (context: Context, meta: Meta<'message'>, config: any) {
   return meta.$send([
     GLOBAL_HELP_PROLOGUE,
-    ...getCommandList(context, meta, null, options.expand),
+    ...getCommandList(context, meta, null, config.expand),
     GLOBAL_HELP_EPILOGUE,
   ].join('\n'))
 }
 
-async function showCommandHelp (command: Command, meta: Meta<'message'>, options: any) {
+async function showCommandHelp (command: Command, meta: Meta<'message'>, config: any) {
   const output = [command.name + command.declaration, command.config.description]
   if (command.context.database) {
     meta.$user = await command.context.database.observeUser(meta.userId)
@@ -109,19 +109,20 @@ async function showCommandHelp (command: Command, meta: Meta<'message'>, options
     }
   }
 
-  if (command._usage) {
-    output.push(command._usage)
+  const usage = command._usage
+  if (usage) {
+    output.push(typeof usage === 'string' ? usage : await usage.call(command, meta))
   }
 
-  const _options = command._options.filter(option => !option.hidden)
-  if (_options.length) {
-    if (_options.some(o => o.authority)) {
+  const options = command._options.filter(option => !option.hidden)
+  if (options.length) {
+    if (options.some(o => o.authority)) {
       output.push('可用的选项有（括号内为额外要求的权限等级）：')
     } else {
       output.push('可用的选项有：')
     }
 
-    _options.forEach((option) => {
+    options.forEach((option) => {
       const authority = option.authority ? `(${option.authority}) ` : ''
       let line = `    ${authority}${option.rawName}  ${option.description}`
       if (option.notUsage && maxUsage !== Infinity) {
@@ -138,7 +139,7 @@ async function showCommandHelp (command: Command, meta: Meta<'message'>, options
   if (command.children.length) {
     output.push(
       '可用的子指令有（括号内为对应的最低权限等级，标有星号的表示含有子指令）：',
-      ...getCommandList(command.context, meta, command, options.expand),
+      ...getCommandList(command.context, meta, command, config.expand),
     )
   }