// ── The SQL half of the configuration audit ───────────────────────────────
//
// One table, two questions: record what a save did, and show an operator what
// has been done to a server lately.
//
// Nothing here talks to a game. The game half is `sidecarClient`, and the two
// are deliberately not mixed: this file is what remains true after the plugin
// has been reloaded, rolled back, or lost.

const core = require('../../core')

/**
 * Records one save attempt — including the ones that never reached a file.
 *
 * A refusal is written for the same reason a success is: an operator asking why
 * a setting is not what they set has to be able to see that somebody tried and
 * was told no, and a table that only holds successes answers that question with
 * silence.
 */
async function recordWrite(row) {
  const result = await core.query(
    `INSERT INTO rust_config_writes
       (server_id, path, plugin, reload_target, tier, user_id, outcome, reloaded,
        changes, version_before, version_after, detail, write_id, settle_by)
     VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, DATE_ADD(NOW(), INTERVAL ? SECOND))`,
    [
      row.serverId,
      row.path,
      row.plugin || null,
      row.reloadTarget || null,
      row.tier || 'form',
      row.userId || null,
      row.outcome,
      row.reloaded ? 1 : 0,
      row.changes ? JSON.stringify(row.changes) : null,
      row.versionBefore || null,
      row.versionAfter || null,
      row.detail ? String(row.detail).slice(0, 500) : null,
      row.writeId || null,
      // Seconds from now, on the database's clock — the one `lost` is read against.
      // NULL for a write nothing is waiting on, and DATE_ADD of NULL is NULL.
      row.settleSeconds != null ? Number(row.settleSeconds) : null,
    ],
  )

  return result && result.insertId != null ? Number(result.insertId) : null
}

/**
 * Settles a `reloading` write from the plugin's `config.outcome` (protocol 13).
 *
 * Found by the plugin's `writeId`, scoped to the server that sent it — a write
 * id is only unique within one plugin. Only a row still `reloading` moves, so a
 * replayed frame settles nothing twice. A row whose `settle_by` has passed is
 * still `reloading` in the table (it reads as `lost`), so a late outcome still
 * lands. Returns whether a row moved.
 */
async function settleWrite(serverId, outcome) {
  const result = await core.query(
    `UPDATE rust_config_writes
        SET outcome = ?, reloaded = ?, restored = ?, version_after = ?, detail = ?,
            log_tail = ?, settled_at = NOW()
      WHERE server_id = ? AND write_id = ? AND outcome = 'reloading'`,
    [
      outcome.outcome,
      outcome.reloaded ? 1 : 0,
      outcome.restored == null ? null : outcome.restored ? 1 : 0,
      outcome.versionAfter || null,
      outcome.detail ? String(outcome.detail).slice(0, 500) : null,
      outcome.log || null,
      serverId,
      outcome.writeId,
    ],
  )

  return Number((result && result.affectedRows) || 0) > 0
}

/** One write, by its row id, for the page that is waiting on it. */
async function getWrite(serverId, id) {
  const rows = await core.query(
    `${SELECT_WRITE}
      WHERE server_id = ? AND id = ?`,
    [serverId, id],
  )

  return rows[0] ? shapeWrite(rows[0]) : null
}

/**
 * The recent history for one server, newest first.
 *
 * `changes` comes back parsed, and a row whose JSON will not parse comes back
 * with `null` rather than throwing — a corrupt audit row must not be able to
 * break the page that displays the rest of them.
 */
async function recentWrites(serverId, limit = 50) {
  const rows = await core.query(
    `${SELECT_WRITE}
      WHERE server_id = ?
      ORDER BY id DESC
      LIMIT ?`,
    [serverId, Math.max(1, Math.min(Number(limit) || 50, 200))],
  )

  return rows.map(shapeWrite)
}

// `lost` is decided by the database's clock, in the same statement that reads
// the row, so it cannot disagree with `settle_by`, which that clock also wrote.
const SELECT_WRITE = `SELECT id, server_id AS serverId, path, plugin, reload_target AS reloadTarget, tier,
            user_id AS userId, outcome, reloaded, restored, changes,
            version_before AS versionBefore, version_after AS versionAfter, detail,
            log_tail AS log, write_id AS writeId, settled_at AS settledAt, created_at AS createdAt,
            (outcome = 'reloading' AND settle_by IS NOT NULL AND settle_by < NOW()) AS lost
       FROM rust_config_writes`

/**
 * A row as the page reads it. A write still `reloading` past its `settle_by`
 * reads as `lost`: the plugin was reloaded or the link dropped before it could
 * say, and the files are whatever a re-read shows.
 */
function shapeWrite(row) {
  const { lost, ...rest } = row

  return {
    ...rest,
    outcome: Number(lost) ? 'lost' : row.outcome,
    reloaded: Boolean(row.reloaded),
    restored: row.restored == null ? null : Boolean(row.restored),
    changes: parseChanges(row.changes),
  }
}

function parseChanges(raw) {
  if (!raw) return null

  try {
    return JSON.parse(raw)
  } catch {
    return null
  }
}

module.exports = { recordWrite, settleWrite, getWrite, recentWrites, parseChanges, shapeWrite }