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

/**
 * The in-WebView terminal 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 the page imports directly. So this
 * is one esbuild bundle of the entry that calls `createTerminalDocument()` with no host, written
 * out as a string exactly as the xterm engine 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 crash reports and in the WebView's own
 * console, and the size it saves is small beside the engine it sits next to.
 */
const mobileRoot = path.join(import.meta.dirname, '..')

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

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

export const TERMINAL_DOCUMENT_SCRIPT_PATH = path.join(
  mobileRoot,
  'src',
  'terminal',
  'terminal-webview-document-script.generated.ts'
)

const GENERATED_HEADER =
  `// Generated by scripts/build-terminal-document-script.mjs. Do not edit.\n` +
  `// The source is mobile/src/terminal/document/, 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.
 *
 * `minify: false` is load-bearing beyond readability: the engine-error overlay reports the line and
 * column `window.onerror` hands it, and a minified document makes both useless.
 *
 * So is `absWorkingDir`: 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 — and from outside the repo the comments carry an absolute path with the builder's home
 * directory in it.
 */
export function terminalDocumentBuildOptions(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, and the pair is
 * what lets a test compare the committed artifact with what the sources say it should be.
 */
export async function terminalDocumentBundle() {
  const result = await esbuild.build(terminalDocumentBuildOptions({ metafile: true }))
  const [output] = result.outputFiles
  if (!output) {
    throw new Error('[build-terminal-document-script] esbuild emitted no document bundle')
  }
  return { script: output.text.trimEnd(), inputs: Object.keys(result.metafile.inputs) }
}

export async function buildTerminalDocumentScript() {
  return (await terminalDocumentBundle()).script
}

async function main() {
  const script = await buildTerminalDocumentScript()
  await writeFile(
    TERMINAL_DOCUMENT_SCRIPT_PATH,
    `${GENERATED_HEADER}\nexport const TERMINAL_DOCUMENT_SCRIPT = ${JSON.stringify(script)}\n`
  )
}

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