// ── Event definitions — the save path ──────────────────────────────────────
//
// EVENTS.md §D and "Versioning, and editing a live event". A definition is
// operator-authored data, and this file is the boundary that decides whether a
// version of it may exist. The authoring UI (Phase 3, then Phase 13) will
// re-check some of this for the sake of a good inline error; that second copy is
// expected to drift, so this one is the one that decides, and a definition
// arriving by any other route gets the same answer.
//
// **The three rules with teeth, and each is a rule about time rather than about
// shape:**
//
// 1. Publishing SNAPSHOTS. It copies the working spec into an immutable
//    `event_versions` row and points `current_version_id` at it. Editing
//    afterwards is free and does not touch the row a live run pinned.
// 2. A dormant step blocks a PUBLISH and never a SAVE. An uninstalled module
//    must not make an author's work uneditable, and it must not let a version be
//    published that names a verb nobody can perform.
// 3. Archiving is what "delete" means here. `event_runs.version_id` RESTRICTs, so
//    a hard delete of a definition that has ever run is refused by the database
//    anyway — and the row's history is the thing an audit reads.

const db = require('./eventDefinitions.db')
const versionsDb = require('./eventVersions.db')
const runsDb = require('./eventRuns.db')
const seriesDb = require('./eventSeries.db')
const spec = require('../../events/spec')
const { slugify, uniqueSlug } = require('../teams/teamSlug')
const { cleanBody } = require('../../utils/sanitizeHtml')

const MAX_TITLE = 200
const MAX_SUMMARY = 500
const MAX_URL = 500
const MAX_CONCURRENCY_KEY = 190

// A day either side of §D's default. Below a minute the grace window cannot
// survive a single slow boot; above a day a "missed" occurrence would start
// silently the following afternoon, which is the exact behaviour §E forbids.
const MIN_GRACE_SECONDS = 60
const MAX_GRACE_SECONDS = 86_400

/**
 * IANA zone names, checked against the platform's own database rather than a
 * list. `Intl.DateTimeFormat` throws `RangeError` on an unknown zone, and Node
 * ships the full tzdata — so this is the same check Phase 4's occurrence
 * arithmetic will make, asked one screen earlier where an operator can fix it.
 */
function isTimezone(tz) {
  try {
    Intl.DateTimeFormat(undefined, { timeZone: tz })
    return true
  } catch {
    return false
  }
}

const isPlainObject = (v) => v !== null && typeof v === 'object' && !Array.isArray(v)

const trimOrNull = (v, max) => {
  if (v === undefined || v === null) return null
  const s = String(v).trim()
  return s === '' ? null : s.slice(0, max)
}

/**
 * Validate an incoming definition against the registries and the schema.
 *
 * `{ ok: true, definition }` with a normalised row ready for insert/update, or
 * `{ ok: false, errors }` listing every problem rather than the first.
 *
 * `existing` is the row being edited, or null on a create. It is what lets a
 * dormant step survive: the ids already in the saved spec widen what the spec
 * validator will accept, so an uninstall is never destructive after the fact.
 */
async function validate(input, { existing = null } = {}) {
  const errors = []
  const body = isPlainObject(input) ? input : {}

  const title = trimOrNull(body.title, MAX_TITLE)
  if (!title) errors.push('title is required')

  const summary = trimOrNull(body.summary, MAX_SUMMARY)
  const imageUrl = trimOrNull(body.imageUrl, MAX_URL)
  const concurrencyKey = trimOrNull(body.concurrencyKey, MAX_CONCURRENCY_KEY)

  // The storyline. Sanitized on write, exactly as a wiki page and a forum post
  // are: it is author-supplied HTML that ends up on a public page.
  const storyline = body.body === undefined || body.body === null ? null : cleanBody(String(body.body))

  const timezone = trimOrNull(body.timezone, 64) || existing?.timezone || 'UTC'
  if (!isTimezone(timezone)) errors.push(`timezone: "${timezone}" is not an IANA zone name`)

  const graceRaw = body.graceSeconds === undefined ? (existing?.grace_seconds ?? 900) : body.graceSeconds
  const graceSeconds = Number(graceRaw)
  if (
    !Number.isInteger(graceSeconds) ||
    graceSeconds < MIN_GRACE_SECONDS ||
    graceSeconds > MAX_GRACE_SECONDS
  ) {
    errors.push(`graceSeconds must be an integer ${MIN_GRACE_SECONDS}..${MAX_GRACE_SECONDS}`)
  }

  let seriesId = null
  if (body.seriesId !== undefined && body.seriesId !== null && body.seriesId !== '') {
    seriesId = Number(body.seriesId)
    if (!Number.isInteger(seriesId) || seriesId < 1) {
      errors.push('seriesId must be an integer')
      seriesId = null
    } else if (!(await seriesDb.exists(seriesId))) {
      // Checked here as well as by the foreign key, because a 1452 reaching a
      // controller is a 500 and this is a 400 an author can act on.
      errors.push(`seriesId ${seriesId} does not exist`)
      seriesId = null
    }
  } else if (existing) {
    seriesId = existing.series_id
  }

  const seriesOrderRaw = body.seriesOrder === undefined ? (existing?.series_order ?? 0) : body.seriesOrder
  const seriesOrder = Number(seriesOrderRaw)
  if (!Number.isInteger(seriesOrder)) errors.push('seriesOrder must be an integer')

  // ── the spec ──
  const rawSpec = body.spec === undefined ? existing?.spec ?? spec.emptySpec() : body.spec
  const known = existing?.spec ? spec.actionIdsIn(existing.spec) : []
  const checked = spec.validate(rawSpec, { knownActionIds: known })
  if (!checked.ok) errors.push(...checked.errors)

  // ── the slug ──
  //
  // Derived from the title on create and FROZEN afterwards, like a Team's: the
  // public event page lives at it, and a retitle must not break a link somebody
  // posted in Discord. An author who genuinely needs a different address makes a
  // new definition.
  let slug = existing?.slug || null
  if (!slug) {
    const stem = slugify(title || '') || 'event'
    const taken = (await db.list()).map((d) => d.slug)
    slug = uniqueSlug(stem, taken, { fallback: 'event' })
  }

  if (errors.length) return { ok: false, errors }

  return {
    ok: true,
    definition: {
      title,
      slug,
      summary,
      body: storyline,
      image_url: imageUrl,
      owner_module: existing?.owner_module ?? null,
      series_id: seriesId,
      series_order: seriesOrder,
      concurrency_key: concurrencyKey,
      grace_seconds: graceSeconds,
      timezone,
      spec: checked.spec,
    },
  }
}

/** Create a draft. */
async function create(input, userId) {
  const result = await validate(input)
  if (!result.ok) return result
  const id = await db.insert({ ...result.definition, created_by: userId })
  return { ok: true, id, definition: await db.getById(id) }
}

/**
 * Edit a definition.
 *
 * An `archived` definition is not editable. That is the one state check here,
 * and it is a real one rather than a formality: archiving is how a definition is
 * retired, and a retired definition that can still be edited is a definition
 * somebody will edit and then wonder why it never runs.
 */
async function save(id, input, userId) {
  const existing = await db.getById(id)
  if (!existing) return { ok: false, status: 404, errors: ['no such event definition'] }
  if (existing.state === 'archived') {
    return { ok: false, status: 409, errors: ['an archived definition cannot be edited'] }
  }
  const result = await validate(input, { existing })
  if (!result.ok) return result
  await db.update(id, { ...result.definition, updated_by: userId })
  return { ok: true, id, definition: await db.getById(id) }
}

/**
 * Publish: snapshot the working spec into an immutable version and go `ready`.
 *
 * The spec is re-validated here against the registries as they stand RIGHT NOW,
 * not trusted from the save that wrote it. A module uninstalled between the two
 * is the whole reason: the save was legitimate, and publishing a version whose
 * steps name a verb nobody can perform would be a run that fails at dispatch
 * with the world half-changed.
 */
async function publish(id, userId) {
  const existing = await db.getById(id)
  if (!existing) return { ok: false, status: 404, errors: ['no such event definition'] }
  if (existing.state === 'archived') {
    return { ok: false, status: 409, errors: ['an archived definition cannot be published'] }
  }

  const checked = spec.validate(existing.spec, {
    knownActionIds: spec.actionIdsIn(existing.spec),
  })
  if (!checked.ok) return { ok: false, status: 400, errors: checked.errors }

  const publishable = spec.publishable(checked.spec)
  if (!publishable.ok) {
    return {
      ok: false,
      status: 409,
      errors: [
        `cannot publish: no module registers ${publishable.dormant.join(', ')}`,
      ],
    }
  }
  if (!checked.spec.phases.some((p) => p.steps.length)) {
    // An empty event publishes cleanly and then does nothing, which looks like a
    // broken run rather than an empty one. Refusing costs an author one click and
    // saves an operator a diagnosis.
    return { ok: false, status: 400, errors: ['cannot publish: no phase has any steps'] }
  }

  const version = await versionsDb.nextVersion(id)
  const versionId = await versionsDb.insert(id, version, checked.spec, userId)
  await db.markReady(id, versionId, userId)
  return { ok: true, versionId, version, definition: await db.getById(id) }
}

/**
 * Archive.
 *
 * Refused while a run of this definition is still in flight — not because the
 * database would object (it would not; archiving is an UPDATE), but because the
 * screen the run is on reads its title and state from here, and retiring a
 * definition mid-run makes the console describe something that is no longer
 * supposed to exist. Cancel the run, then archive.
 */
async function archive(id, userId) {
  const existing = await db.getById(id)
  if (!existing) return { ok: false, status: 404, errors: ['no such event definition'] }
  if (existing.state === 'archived') return { ok: true, definition: existing }

  const active = await runsDb.countActiveForDefinition(id)
  if (active > 0) {
    return {
      ok: false,
      status: 409,
      errors: [`cannot archive: ${active} run(s) of this definition are still in flight`],
    }
  }
  await db.archive(id, userId)
  return { ok: true, definition: await db.getById(id) }
}

module.exports = {
  validate,
  create,
  save,
  publish,
  archive,
  isTimezone,
  MIN_GRACE_SECONDS,
  MAX_GRACE_SECONDS,
}