import { writeFile } from 'node:fs/promises'
import path from 'node:path'
import esbuild from 'esbuild'

/**
 * The in-WebView rich Markdown editor document, bundled from its modules.
 *
 * The document is a string the native WebView loads inside its HTML, so it cannot be an ES module
 * there — and it is ordinary TypeScript everywhere else, which a page imports directly. So this is
 * one esbuild bundle of the entry that calls `createRichMarkdownEditorDocument()` with no host,
 * written out as a string, exactly as the terminal's document beside it is.
 *
 * `iife`, so the bundle's module scope is its own and nothing it declares reaches the page it is
 * pasted into. Not minified: the document is read in the WebView's own console, and it is a few
 * tens of kilobytes rather than an engine.
 */
const mobileRoot = path.join(import.meta.dirname, '..')

/** The oldest WebView Orca supports, matching the terminal document's own floor (#7030). */
const TARGET = 'chrome74'

const ENTRY = path.join(
  mobileRoot,
  'src',
  'components',
  'rich-markdown',
  'native-document-entry.ts'
)

export const RICH_MARKDOWN_EDITOR_SCRIPT_PATH = path.join(
  mobileRoot,
  'src',
  'components',
  'rich-markdown-editor-document-script.generated.ts'
)

const GENERATED_HEADER =
  `// Generated by scripts/build-rich-markdown-editor-script.mjs. Do not edit.\n` +
  `// The source is mobile/src/components/rich-markdown/, bundled from native-document-entry.ts.\n` +
  `// Target: ${TARGET}. Regenerate via pnpm postinstall.`

/**
 * One options object, so a census of what the bundle contains measures the bundle that ships.
 *
 * `absWorkingDir` is load-bearing: esbuild writes each module's path into the bundle as a comment,
 * relative to the working directory, so without it the artifact's bytes depend on where the
 * generator was run from — three cwds gave three digests, and from outside the repo the comments
 * carry an absolute path with the builder's home directory in it.
 */
export function richMarkdownEditorBuildOptions(extra = {}) {
  return {
    absWorkingDir: mobileRoot,
    entryPoints: [ENTRY],
    bundle: true,
    format: 'iife',
    minify: false,
    platform: 'browser',
    target: TARGET,
    legalComments: 'none',
    write: false,
    logLevel: 'silent',
    ...extra
  }
}

/**
 * One bundle, and everything a reader asks about it.
 *
 * The text and the module list come from the same build because they are two readings of one
 * thing: a census that built its own would answer about a bundle nobody ships.
 */
export async function richMarkdownEditorBundle() {
  const result = await esbuild.build(richMarkdownEditorBuildOptions({ metafile: true }))
  const [output] = result.outputFiles
  if (!output) {
    throw new Error('[build-rich-markdown-editor-script] esbuild emitted no document bundle')
  }
  return { script: output.text.trimEnd(), inputs: Object.keys(result.metafile.inputs) }
}

export async function buildRichMarkdownEditorScript() {
  return (await richMarkdownEditorBundle()).script
}

async function main() {
  const script = await buildRichMarkdownEditorScript()
  await writeFile(
    RICH_MARKDOWN_EDITOR_SCRIPT_PATH,
    `${GENERATED_HEADER}\nexport const RICH_MARKDOWN_EDITOR_DOCUMENT_SCRIPT = ${JSON.stringify(script)}\n`
  )
}

if (process.argv[1] && import.meta.url.endsWith(path.basename(process.argv[1]))) {
  await main()
}