provide error checking on inputs

src/config.ts

@@ -1,20 +1,77 @@
 import * as core from '@actions/core'
 
-export type Action = 'check' | 'uncheck' | 'detect' | 'current-detect'
+/**
+ * Action
+ */
+export const actions = ['check', 'uncheck', 'detect', 'current-detect'] as const
+
+const isAction = (action: string): action is Action => {
+  return actions.includes(action as Action)
+}
+
+const getAction = (): Action => {
+  const action = core.getInput('action', {required: true})
+  if (!isAction(action)) {
+    throw new Error(`Invalid action: ${action}`)
+  }
+  return action
+}
+
+export type Action = (typeof actions)[number]
+export const action = getAction()
+
+/**
+ * Error Level
+ */
+const errors = ['error', 'warn', 'ignore'] as const
+const isError = (error: string): error is ErrorLevel => {
+  return errors.includes(error as ErrorLevel)
+}
+const getError = (): ErrorLevel => {
+  const error = core.getInput('error', {required: true})
+  if (!isError(error)) {
+    throw new Error(`Invalid error: ${error}`)
+  }
+  return error
+}
+
+/**
+ * How verbose should feedback be?
+ */
 export type ErrorLevel = 'error' | 'warn' | 'ignore'
+export const error = getError()
 
+/**
+ * List of checkboxes to operate on
+ */
 export const list = core.getMultilineInput('list', {required: false})
+
+/**
+ * A regex to match checkboxes which should be operated on
+ */
 export const matches = core.getInput('matches', {required: false})
-export const action: Action = core.getInput('action', {
-  required: true
-}) as Action
-export const error = core.getInput('error', {required: true}) as ErrorLevel
+
 export const token = core.getInput('GITHUB_TOKEN', {required: true})
 
 export type ConfigPayload = {
+  /**
+   * @see {@link list}
+   */
   list: string[]
+  /**
+   * @see {@link matches}
+   */
   matches: string
+  /**
+   * @see {@link Action}
+   */
   action: Action
+  /**
+   * @see {@link ErrorLevel}
+   */
   error: ErrorLevel
+  /**
+   * @see {@link token}
+   */
   token: string
 }

src/main.ts

@@ -14,15 +14,29 @@ async function run(): Promise<void> {
     if (action === 'detect') {
       const previousBody = getPreviousBody()
       const currentBody = getCurrentBody()
-      const changed = getDiff(previousBody, currentBody)
-      const checked = getCurrentChecked(currentBody)
-      const unchecked = getCurrentUnchecked(currentBody)
+      const {checked, unchecked} = getDiff(
+        previousBody.split('\n'),
+        currentBody.split('\n')
+      )
 
       core.setOutput('checked', JSON.stringify(checked))
       core.setOutput('unchecked', JSON.stringify(unchecked))
-      core.setOutput('changed', JSON.stringify(changed))
       return
     }
+
+    if (action === 'current-detect') {
+      const currentBody = getCurrentBody()
+      const checked = getCurrentChecked(currentBody.split('\n'))
+      const unchecked = getCurrentUnchecked(currentBody.split('\n'))
+
+      core.setOutput('checked', JSON.stringify(checked))
+      core.setOutput('unchecked', JSON.stringify(unchecked))
+      return
+    }
+
+    /**
+     * check or uncheck action
+     */
     let body = await getBody()
     if (!contains(body)) {
       switch (error) {