// ── event_definitions — SQL only ───────────────────────────────────────────
//
// EVENTS.md §D. The `.db.js` half of the pair: parameterised SQL and hydration,
// no policy. Everything that decides whether a write is allowed lives in
// `eventDefinitions.model.js`.

const { query } = require('../../utils/db')
const { parseJson } = require('./eventJson')

const hydrate = (row) =>
  row && {
    ...row,
    spec: parseJson(row.spec, null),
  }

// `current_version` is joined rather than stored: the list screen shows "v3" and
// the column that would hold it is a denormalisation of a row this query already
// has to reach for the publish date anyway.
const SELECT_LIST = `
  SELECT d.*, s.name AS series_name, s.slug AS series_slug,
         v.version AS current_version
    FROM event_definitions d
    LEFT JOIN event_series   s ON s.id = d.series_id
    LEFT JOIN event_versions v ON v.id = d.current_version_id
`

const list = async ({ state = null } = {}) => {
  const rows = state
    ? await query(`${SELECT_LIST} WHERE d.state = ? ORDER BY d.updated_at DESC, d.id DESC`, [state])
    : await query(`${SELECT_LIST} ORDER BY d.updated_at DESC, d.id DESC`)
  return rows.map(hydrate)
}

const getById = async (id) => {
  const [row] = await query(`${SELECT_LIST} WHERE d.id = ?`, [id])
  return hydrate(row)
}

const getBySlug = async (slug) => {
  const [row] = await query(`${SELECT_LIST} WHERE d.slug = ?`, [slug])
  return hydrate(row)
}

/** Does any OTHER definition hold this slug? The uniqueness pre-check. */
const slugTaken = async (slug, exceptId = null) => {
  const rows = exceptId
    ? await query('SELECT id FROM event_definitions WHERE slug = ? AND id <> ?', [slug, exceptId])
    : await query('SELECT id FROM event_definitions WHERE slug = ?', [slug])
  return rows.length > 0
}

const insert = async (d) => {
  const result = await query(
    `INSERT INTO event_definitions
       (title, slug, summary, body, image_url, owner_module, series_id, series_order,
        concurrency_key, grace_seconds, timezone, spec, created_by, updated_by)
     VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
    [
      d.title,
      d.slug,
      d.summary,
      d.body,
      d.image_url,
      d.owner_module,
      d.series_id,
      d.series_order,
      d.concurrency_key,
      d.grace_seconds,
      d.timezone,
      JSON.stringify(d.spec),
      d.created_by,
      d.created_by,
    ],
  )
  return result.insertId
}

const update = (id, d) =>
  query(
    `UPDATE event_definitions
        SET title = ?, slug = ?, summary = ?, body = ?, image_url = ?, series_id = ?,
            series_order = ?, concurrency_key = ?, grace_seconds = ?, timezone = ?,
            spec = ?, updated_by = ?
      WHERE id = ?`,
    [
      d.title,
      d.slug,
      d.summary,
      d.body,
      d.image_url,
      d.series_id,
      d.series_order,
      d.concurrency_key,
      d.grace_seconds,
      d.timezone,
      JSON.stringify(d.spec),
      d.updated_by,
      id,
    ],
  )

/**
 * Point a definition at the version it just published, and mark it `ready`.
 *
 * One statement, because the two halves are the same fact: `ready` means "a
 * version has been published and the schedule is live" (§E), so a state without
 * a `current_version_id` is a lie the scheduler would act on.
 */
const markReady = (id, versionId, userId) =>
  query(
    `UPDATE event_definitions
        SET state = 'ready', current_version_id = ?, updated_by = ?
      WHERE id = ?`,
    [versionId, userId, id],
  )

/**
 * Every definition the runner should expand a recurrence for (Phase 4).
 *
 * `ready` is the whole gate, and it is deliberately the only one: EVENTS.md §E
 * defines `ready` as "a version has been published and the schedule is live", so
 * publishing IS the switch and archiving is how an operator turns a recurrence
 * off. A separate schedule-enabled flag would be a second answer to a question
 * `state` already answers, and the two would eventually disagree.
 *
 * The VERSION's spec is joined rather than the definition's working copy: the
 * draft is what an author is midway through editing, and a half-typed `weekly`
 * must never materialise anything. The pinned spec comes back with it, so the
 * whole expansion is one round trip.
 *
 * The series columns are here for the CALENDAR rather than the runner, which
 * ignores them: a projected occurrence has to be filterable and labellable by
 * its arc exactly as a materialised run is, and a second query to learn the name
 * of a row this one already reached would be two round trips for a join.
 */
const findSchedulable = async () => {
  const rows = await query(
    `SELECT d.id, d.title, d.slug, d.timezone, d.grace_seconds, d.concurrency_key,
            d.current_version_id, d.series_id, v.spec AS version_spec,
            s.name AS series_name, s.slug AS series_slug
       FROM event_definitions d
       JOIN event_versions v ON v.id = d.current_version_id
       LEFT JOIN event_series s ON s.id = d.series_id
      WHERE d.state = 'ready'
      ORDER BY d.id`,
  )
  return rows.map((row) => ({ ...row, version_spec: parseJson(row.version_spec, null) }))
}

/**
 * Archive. Never a hard delete while runs reference it (§ API surface) — and the
 * schema would refuse one anyway, because `event_runs.version_id` RESTRICTs.
 * Archiving is what "delete" means on this screen, and the row keeps its history.
 */
const archive = (id, userId) =>
  query("UPDATE event_definitions SET state = 'archived', updated_by = ? WHERE id = ?", [userId, id])

module.exports = {
  list,
  getById,
  getBySlug,
  slugTaken,
  findSchedulable,
  insert,
  update,
  markReady,
  archive,
}