// Generates the Yjs wire fixtures that define compatibility for the Rust
// core. These are the contract: never edit a fixture to make a test pass.
// A deliberate rule change regenerates them in the same commit.
import * as Y from 'yjs'
import { mkdirSync, writeFileSync } from 'node:fs'
import { join, dirname } from 'node:path'
import { fileURLToPath } from 'node:url'

const dataDir = join(dirname(fileURLToPath(import.meta.url)), 'data')
mkdirSync(dataDir, { recursive: true })

function emit(name, build) {
  const doc = new Y.Doc()
  // new Y.Doc() assigns a random clientID. Fixed IDs ensure that running the
  // generator twice produces byte-identical fixtures (required for the
  // regeneration gate that later tasks add).
  doc.clientID = 1
  build(doc)
  const update = Y.encodeStateAsUpdate(doc)
  writeFileSync(join(dataDir, `${name}.update.bin`), Buffer.from(update))
  writeFileSync(
    join(dataDir, `${name}.expected.json`),
    JSON.stringify({
      text: doc.getText('content').toString(),
      delta: doc.getText('content').toDelta()
    }, null, 2) + '\n'
  )
  console.log(`${name}: ${update.length} bytes`)
}

emit('hello', (doc) => {
  doc.getText('content').insert(0, 'hello world')
})

emit('unicode', (doc) => {
  // Surrogate pairs and combining marks: Yjs indexes UTF-16 code units and
  // Rust indexes UTF-8 bytes, so this is where an index-conversion bug shows.
  doc.getText('content').insert(0, 'héllo 🌍 café')
})

emit('formatted', (doc) => {
  // Rich text formatting: bold is the key assertion. The delta field captures
  // the formatting structure that toString() would strip, verifying that the
  // Rust side correctly decodes format operations.
  const t = doc.getText('content')
  t.insert(0, 'plain bold plain')
  t.format(6, 4, { bold: true })
})

emit('concurrent', (doc) => {
  // Two docs diverge and merge. The merged state is order-independent, so
  // Rust must arrive at the same bytes from the same inputs.
  const a = new Y.Doc()
  a.clientID = 1
  const b = new Y.Doc()
  b.clientID = 2
  // Note: doc.clientID (set to 3 here) overrides the emit() assignment above.
  // The clientID of this local doc must differ from a and b to ensure
  // deterministic merge ordering.
  doc.clientID = 3
  a.getText('content').insert(0, 'AAA')
  b.getText('content').insert(0, 'BBB')
  Y.applyUpdate(a, Y.encodeStateAsUpdate(b))
  Y.applyUpdate(b, Y.encodeStateAsUpdate(a))
  Y.applyUpdate(doc, Y.encodeStateAsUpdate(a))
})