generate-github-readme.ts

#!/usr/bin/env bun

import { readFileSync, writeFileSync } from "node:fs"
import { resolve } from "node:path"

type ManifestVariable = {
  name: string
  required?: boolean
  sensitive?: boolean
  defaultValue?: string
  githubSource: string
  description: string
}

type Manifest = {
  variables: ManifestVariable[]
}

const START_MARKER = "<!-- GENERATED_ENV_TABLE_START -->"
const END_MARKER = "<!-- GENERATED_ENV_TABLE_END -->"
const MANIFEST_PATH = resolve(import.meta.dir, "..", "env", "deploy.manifest.json")
const README_PATH = resolve(import.meta.dir, "..", "README.md")

function readManifest(path: string) {
  const parsed = JSON.parse(readFileSync(path, "utf8")) as Manifest
  if (!Array.isArray(parsed.variables)) {
    throw new Error(`Manifest must contain variables array: ${path}`)
  }
  return parsed.variables
}

function markdownEscape(text: string) {
  return text.replaceAll("|", "\\|")
}

function buildGeneratedBlock(vars: ManifestVariable[]) {
  const rows = vars.map((v) => {
    const required = v.required ? "yes" : "no"
    const notes = [
      v.description,
      v.defaultValue !== undefined ? `Default: \`${v.defaultValue}\`.` : "",
      v.sensitive ? "Sensitive." : "",
    ]
      .filter(Boolean)
      .join(" ")
    return `| \`${v.name}\` | \`${v.githubSource}\` | ${required} | ${markdownEscape(notes)} |`
  })

  return [
    START_MARKER,
    "<!-- This block is GENERATED. Edit .github/env/deploy.manifest.json and run `bun .github/scripts/generate-github-readme.ts`. -->",
    "| Name | Source | Required | Description |",
    "| --- | --- | --- | --- |",
    ...rows,
    END_MARKER,
  ].join("\n")
}

function main() {
  const variables = readManifest(MANIFEST_PATH)
  const generatedBlock = buildGeneratedBlock(variables)
  const readme = readFileSync(README_PATH, "utf8")

  if (!readme.includes(START_MARKER) || !readme.includes(END_MARKER)) {
    throw new Error(`README is missing generation markers: ${START_MARKER} / ${END_MARKER}`)
  }

  const start = readme.indexOf(START_MARKER)
  const end = readme.indexOf(END_MARKER)
  const before = readme.slice(0, start).trimEnd()
  const after = readme.slice(end + END_MARKER.length).trimStart()
  const updated = `${before}\n\n${generatedBlock}\n\n${after}\n`
  writeFileSync(README_PATH, updated, "utf8")
  process.stdout.write(`Updated ${README_PATH}\n`)
}

main()