Implement fetching, filtering and tests

src/main.ts

@@ -1,19 +1,54 @@
 import * as core from '@actions/core'
-import {wait} from './wait'
+import * as github from '@actions/github'
+import {Webhooks} from '@octokit/webhooks'
+
+import Filter from './filter'
 
 async function run(): Promise<void> {
   try {
-    const ms: string = core.getInput('milliseconds')
-    core.debug(`Waiting ${ms} milliseconds ...`)
+    const token = core.getInput('github-token', {required: true})
+    const filterYaml = core.getInput('filter', {required: true})
+    const client = new github.GitHub(token)
 
-    core.debug(new Date().toTimeString())
-    await wait(parseInt(ms, 10))
-    core.debug(new Date().toTimeString())
+    if (github.context.eventName !== 'pull_request') {
+      core.setFailed('This action can be triggered only by pull_request event')
+      return
+    }
 
-    core.setOutput('time', new Date().toTimeString())
+    const pr = github.context.payload.pull_request as Webhooks.WebhookPayloadPullRequestPullRequest
+    const filter = new Filter(filterYaml)
+    const files = await getChangedFiles(client, pr)
+
+    const result = filter.match(files)
+    for (const key in result) {
+      core.setOutput(key, String(result[key]))
+    }
   } catch (error) {
     core.setFailed(error.message)
   }
 }
 
+// Uses github REST api to get list of files changed in PR
+async function getChangedFiles(
+  client: github.GitHub,
+  pullRequest: Webhooks.WebhookPayloadPullRequestPullRequest
+): Promise<string[]> {
+  const pageSize = 100
+  const files: string[] = []
+  for (let page = 0; page * pageSize < pullRequest.changed_files; page++) {
+    const response = await client.pulls.listFiles({
+      owner: github.context.repo.owner,
+      repo: github.context.repo.repo,
+      pull_number: pullRequest.number,
+      page,
+      per_page: pageSize
+    })
+    for (const row of response.data) {
+      files.push(row.filename)
+    }
+  }
+
+  return files
+}
+
 run()