// ── Event runs — creating an occurrence ────────────────────────────────────
//
// EVENTS.md §E. Phase 1 creates a run row and materialises the first phase's
// steps. **It does not start anything**: there is no runner until Phase 2, so a
// row created here sits at `scheduled` indefinitely. That is the correct
// behaviour for this phase and it has to be VISIBLE as such rather than looking
// broken, which is why `create()` answers with the row and the admin surface
// renders the status verbatim.
//
// Two properties this file owns, both of which are the reason it exists before
// the runner rather than with it:
//
// - **Materialisation is `INSERT IGNORE` against the occurrence key.** Two
//   attempts at one occurrence produce one row and an honest answer, not a
//   duplicate-key error a caller has to interpret. The unique index — not a
//   claim — is what makes "one run per occurrence per scope" true (§E).
// - **The idempotency key is minted with the step row and never varies by
//   attempt.** It is a function of identity, so it can only be stable if it is
//   stamped where the identity is created.

const db = require('./eventRuns.db')
const stepsDb = require('./eventRunSteps.db')
const logDb = require('./eventRunLog.db')
const gatesDb = require('./eventPhaseGates.db')
const gates = require('../../events/gates')
const definitionsDb = require('./eventDefinitions.db')
const versionsDb = require('./eventVersions.db')
const settingsDb = require('./eventActionSettings.db')
const budgetDb = require('./eventRunBudget.db')
const resourcesDb = require('./eventRunResources.db')
const participantsDb = require('./eventRunParticipants.db')
const authorize = require('../../events/authorize')

const MAX_SCOPE = 190

/**
 * Render a definition's `concurrency_key` template against a run's params.
 *
 * `invasion:{region}` with `{ region: 'Yew' }` becomes `invasion:Yew` (§E). A
 * placeholder with no matching param is left standing rather than replaced with
 * an empty string: `invasion:` would collide with every other unrendered key on
 * the deployment, which is the opposite of what a concurrency key is for, and a
 * literal `invasion:{region}` in the column is a visible mistake.
 */
function renderConcurrencyKey(template, params) {
  if (!template) return null
  return String(template)
    .replace(/\{([a-zA-Z][a-zA-Z0-9_]*)\}/g, (whole, name) => {
      const value = params && params[name]
      return value === undefined || value === null || value === '' ? whole : String(value)
    })
    .slice(0, MAX_SCOPE)
}

/**
 * Create one occurrence of a definition and materialise its first phase.
 *
 * `scheduledFor` defaults to now — "start now" is an occurrence whose instant is
 * the present, not a separate concept, which is what keeps the runner's one
 * materialise/advance path honest now that Phase 4 has put recurrence on top.
 *
 * **Phase 4's expansion calls this, rather than a second insert path beside it.**
 * That is deliberate: every check here — the definition is still `ready`, the
 * version still has phases, the concurrency key renders, the first phase's steps
 * are materialised with their idempotency keys — is one a scheduled occurrence
 * needs at least as much as a hand-started one, because there is nobody watching
 * when it happens. The `INSERT IGNORE` answering `created: false` is what makes
 * it safe to call on every tick for every occurrence inside the horizon.
 */
async function create(
  definitionId,
  { scope = '', scheduledFor = null, rehearsal = false, params = null, source = 'manual' } = {},
  userId,
) {
  const definition = await definitionsDb.getById(definitionId)
  if (!definition) return { ok: false, status: 404, errors: ['no such event definition'] }
  if (definition.state !== 'ready') {
    return {
      ok: false,
      status: 409,
      errors: [`a ${definition.state} definition has no published version to run`],
    }
  }
  if (!definition.current_version_id) {
    return { ok: false, status: 409, errors: ['this definition has no published version'] }
  }

  const version = await versionsDb.getById(definition.current_version_id)
  if (!version?.spec?.phases?.length) {
    return { ok: false, status: 409, errors: ['the published version has no phases'] }
  }

  // §K's last bound, enforced for SCHEDULED starts only (org lead, 2026-09-03):
  // *"a scheduled definition that has never been verified is the case worth
  // refusing to start"*. An admin pressing start is watching, and that human IS
  // the review the gate exists to require — so the gate falls on the path where
  // nobody is. A version is immutable, so a dry run that passed against it stays
  // true, which is what makes the pass a property of the version rather than
  // something re-earned every occurrence.
  if (source === 'schedule' && !version.verified_at) {
    return {
      ok: false,
      status: 409,
      code: 'unverified',
      errors: ['this version has not been verified, so it will not start unattended'],
    }
  }

  const scopeValue = String(scope || '').slice(0, MAX_SCOPE)
  const when = scheduledFor ? new Date(scheduledFor) : new Date()
  if (Number.isNaN(when.getTime())) {
    return { ok: false, status: 400, errors: ['scheduledFor is not a date'] }
  }

  const runId = await db.materialise({
    definition_id: definitionId,
    version_id: version.id,
    scope: scopeValue,
    // Stored as UTC. The definition's zone is what an occurrence is COMPUTED in
    // (Phase 4); what is stored is the instant.
    scheduled_for: when,
    timezone: definition.timezone,
    concurrency_key: renderConcurrencyKey(definition.concurrency_key, params),
    params,
    rehearsal,
    started_by: userId,
  })

  if (runId === null) {
    // The occurrence already existed. Not an error — it is what the unique index
    // is for — so the existing row is the answer.
    const existing = await db.findOccurrence(definitionId, scopeValue, when)
    return { ok: true, created: false, run: existing }
  }

  await logDb.write({
    runId,
    kind: 'run.created',
    detail: {
      definitionId,
      versionId: version.id,
      version: version.version,
      scope: scopeValue,
      rehearsal: Boolean(rehearsal),
      // 'manual' is an admin pressing start; 'schedule' is the runner expanding
      // a recurrence (Phase 4). Both produce the same row, and the log is the
      // only place the difference is recorded — `started_by` is NULL for both a
      // scheduled occurrence and one started by a since-deleted account.
      source,
      by: userId,
    },
  })

  // The run's budget, seeded from EVERY phase's steps rather than from the first
  // one's (Phase 6). The version is pinned and immutable, so all of its steps are
  // knowable now — and a budget that grew as phases were entered would let a
  // phase-1 step spend a cap that a phase-3 step was going to need, which is the
  // opposite of a per-run bound. The caps are copied here, so an admin moving a
  // switch tomorrow does not change what a run already in flight is allowed.
  const allSteps = version.spec.phases.flatMap((p) =>
    (p.steps || []).map((s) => ({ actionId: s.actionId, params: s.params || {} })),
  )
  const settingsByAction = await settingsDb.byIds(allSteps.map((s) => s.actionId))
  const budget = authorize.effectiveCaps(allSteps, settingsByAction)
  if (Object.keys(budget).length) {
    await budgetDb.seed(runId, budget)
    await logDb.write({
      runId,
      kind: 'run.budget',
      detail: {
        dimensions: Object.entries(budget).map(([dimension, d]) => ({
          dimension,
          cap: d.cap,
          from: d.from,
        })),
      },
    })
  }

  // The first phase's steps, materialised at creation rather than at start.
  // Phase 2 materialises each LATER phase as the run enters it; doing the first
  // one here is what makes a Phase 1 run row inspectable — an operator can see
  // the steps that would run, with their params and their idempotency keys,
  // before there is anything to run them.
  const first = version.spec.phases[0]
  await stepsDb.materialisePhase(runId, first.key, first.steps || [])
  await logDb.write({ runId, kind: 'phase.entered', phase: first.key, detail: { steps: (first.steps || []).length } })

  return { ok: true, created: true, run: await db.getById(runId) }
}

/**
 * A run, its steps, its status counts and its phase gates — the run console.
 *
 * The gates arrive already DESCRIBED rather than as rows (Phase 5): the panel's
 * whole value is that it reads the way the condition builder reads, and those
 * words come from `engagement/conditions.js`'s own operator labels. Rendering
 * them in the browser would be a second implementation of a grammar the server
 * owns, and the first clause the two spelled differently would meet its operator
 * at two in the morning.
 *
 * Every gate the run has opened is returned, not only the current phase's. A
 * completed phase's gate answers "how long did phase 2 actually wait, and what
 * released it" — which is the same question as the live one, asked afterwards.
 */
async function detail(runId) {
  const run = await db.getById(runId)
  if (!run) return null
  const [steps, counts, gateRows, budget, resources, attendees] = await Promise.all([
    stepsDb.listForRun(runId),
    stepsDb.statusCounts(runId),
    gatesDb.listForRun(runId),
    budgetDb.forRun(runId),
    resourcesDb.forRun(runId),
    participantsDb.listForRun(runId),
  ])
  const now = new Date()
  return {
    run,
    steps,
    counts,
    gates: gateRows.map((g) => gates.describe(g, now)),
    // The meter, as rows rather than as a sentence: a cap is two numbers and a
    // name, and unlike a gate it needs no grammar rendered to be read. `cap:
    // null` is uncapped and the client says so — a dimension the run counts but
    // nothing bounds.
    budget: budget.map((b) => ({
      dimension: b.dimension,
      consumed: b.consumed,
      cap: b.cap,
      from: b.effective_from,
    })),
    // What this run changed in the world, and what became of it (Phase 8). The
    // WHOLE ledger, reverted rows included, because "what did last night's
    // invasion actually spawn, and did all of it come back" is the question this
    // panel exists for and a list of only the failures cannot answer the second
    // half of it.
    //
    // **The `@step` placeholders are filtered out.** They are core's own
    // bookkeeping — a row that says "a dispatch is in flight and may have made
    // something" — and the console's list is of things in the world. One left in
    // would read as a resource nobody can name, which is exactly the confusion it
    // exists to prevent internally.
    resources: resources
      .filter((r) => r.kind !== resourcesDb.STEP_KIND)
      .map((r) => ({
        id: r.id,
        stepId: r.step_id,
        module: r.owner_module,
        kind: r.kind,
        ref: r.ref,
        payload: r.payload,
        leaseUntil: r.lease_until,
        status: r.status,
        revertAttempts: r.revert_attempts,
        lastError: r.last_error,
        memberKey: r.member_key,
        createdAt: r.created_at,
      })),
    // How many rows are still unresolved, counted over the WHOLE ledger rather
    // than over the list above — a placeholder left standing by a lost
    // acknowledgement is exactly the case `cleanup_status` must not call clean.
    unresolvedResources: resources.filter((r) => resourcesDb.UNRESOLVED.includes(r.status)).length,
    // Who took part, best first (Phase 10). Returned on every run rather than
    // only on a published one: the console's question is "what did this event
    // record", and a run whose module has collected but whose author never
    // placed a publish step is exactly the case an operator needs to see. What
    // `results_published_at` on the run row then says is whether anyone OUTSIDE
    // this screen may read it — which is Phase 14's question, not this one's.
    //
    // **`rank` is `rank_at`, renamed at the boundary and not in the column.**
    // `rank` is a reserved word in MariaDB 10.2+ (it is the window function),
    // so the column carries the suffix and the API carries the name a client
    // wants. The alternative — backticking the column at every use — is one
    // forgotten pair of backticks away from a syntax error in a query nobody
    // runs until a run completes at four in the morning.
    participants: attendees.map((p) => ({
      memberKey: p.member_key,
      userId: p.user_id,
      score: p.score,
      rank: p.rank_at,
      joinedAt: p.joined_at,
      meta: p.meta,
    })),
  }
}

module.exports = { create, detail, renderConcurrencyKey }