// Generates the vectors that hold the Rust core to this module's result
// (spec §2.8, Docs' rule adopted unchanged). For each data/<name>.json —
// {guid, ops} — a fresh Y.Doc with that guid and clientID 1 takes the
// ops through applyOps; vectors/<name>.yjs is the whole state as a v1
// update and vectors/<name>.view.json is this side's view of it.
// internal/slides/core/vectors_test.go loads each .yjs through the core
// and compares views, and applies the same ops through the core's own
// Ops and compares again.
//
// These are the contract: never edit a vector to make a test pass. A
// deliberate rule change regenerates them in the same commit. The ids
// come from the data files so a run is the same bytes every time.
import * as Y from 'yjs'
import { mkdirSync, readdirSync, readFileSync, writeFileSync } from 'node:fs'
import { join, dirname } from 'node:path'
import { fileURLToPath } from 'node:url'
import { applyOps, view } from './ops.mjs'
import { checkDoc } from './check.mjs'

const here = dirname(fileURLToPath(import.meta.url))
export const dataDir = join(here, 'data')
export const vectorsDir = join(here, 'vectors')

/** JSON with every object's keys sorted, pretty-printed, newline-terminated. */
export function sortedJSON (v) {
  const sort = x => {
    if (Array.isArray(x)) return x.map(sort)
    if (x !== null && typeof x === 'object') {
      const out = {}
      for (const k of Object.keys(x).sort()) out[k] = sort(x[k])
      return out
    }
    return x
  }
  return JSON.stringify(sort(v), null, 2) + '\n'
}

/** The update and view for one data file's ops. */
export function buildVector (name, data) {
  if (data.guid !== name) throw new Error(`${name}.json: guid ${JSON.stringify(data.guid)} must equal the file name`)
  const doc = new Y.Doc({ guid: data.guid })
  doc.clientID = 1
  applyOps(doc, data.ops)
  // What the ops write must pass the accepted-shape check the server
  // gates a posted update on (check.mjs, core/src/check.rs) — a vector
  // that did not would be a contract the wire refuses.
  const problem = checkDoc(doc)
  if (problem) throw new Error(`${name}: the ops produced text outside the schema: ${problem}`)
  return { update: Y.encodeStateAsUpdate(doc), view: view(doc) }
}

export function generate () {
  mkdirSync(vectorsDir, { recursive: true })
  const names = readdirSync(dataDir).filter(f => f.endsWith('.json')).map(f => f.slice(0, -5)).sort()
  for (const name of names) {
    const data = JSON.parse(readFileSync(join(dataDir, `${name}.json`), 'utf8'))
    const { update, view: v } = buildVector(name, data)
    writeFileSync(join(vectorsDir, `${name}.yjs`), Buffer.from(update))
    writeFileSync(join(vectorsDir, `${name}.view.json`), sortedJSON(v))
    console.log(`${name}: ${data.ops.length} ops, ${update.length} bytes`)
  }
}

if (process.argv[1] && fileURLToPath(import.meta.url) === process.argv[1]) generate()