/** Normalization, replay safety, and surface policy for HUX-01. */

import {
  isOpaqueId,
  isRfc3339Utc,
  safeEvidenceLabel,
  safeText,
} from "./security.ts";
import type {
  ActivityItem,
  ActivityPhase,
  ActivityTone,
  CancellationReceipt,
  HuxSurface,
  MergeResult,
  RawActivityEvent,
  RawCancellationReceipt,
  SurfacePolicy,
} from "./types.ts";

export const ACTIVITY_TIMELINE_FLAG = "hux.activity_timeline";
export const FOUNDATION_FLAG = "hux.foundation";

const EVENT_KINDS = new Set([
  "message.user",
  "message.assistant",
  "decision.route",
  "decision.plan",
  "tool.call",
  "tool.result",
  "approval.requested",
  "approval.resolved",
  "memory.proposed",
  "memory.committed",
  "memory.forgotten",
  "artifact.created",
  "artifact.version",
  "artifact.promoted",
  "citation.attached",
  "mode.changed",
  "run.started",
  "run.cancelled",
  "run.completed",
  "run.failed",
  "privacy.notice",
  "suggestion.shown",
  "suggestion.dismissed",
  "release.transition",
  "delegation.started",
  "delegation.completed",
  "delegation.failed",
  "memory.suppressed",
  "memory.retrieval_removed",
  "budget.exhausted",
  "side_effect.blocked",
  "side_effect.released",
]);

const SURFACE_POLICIES: Readonly<Record<HuxSurface, SurfacePolicy>> = {
  chat: {
    maxItems: 80,
    initialItems: 12,
    evidenceLimit: 3,
    cancellationEffectLimit: 4,
    expandRoutineEvents: false,
  },
  worker: {
    maxItems: 250,
    initialItems: 40,
    evidenceLimit: 8,
    cancellationEffectLimit: 12,
    expandRoutineEvents: true,
  },
  telegram: {
    maxItems: 40,
    initialItems: 8,
    evidenceLimit: 2,
    cancellationEffectLimit: 3,
    expandRoutineEvents: false,
  },
  voice: {
    maxItems: 24,
    initialItems: 6,
    evidenceLimit: 1,
    cancellationEffectLimit: 2,
    expandRoutineEvents: false,
  },
  api: {
    maxItems: 250,
    initialItems: 40,
    evidenceLimit: 8,
    cancellationEffectLimit: 12,
    expandRoutineEvents: true,
  },
};

export function surfacePolicy(surface: HuxSurface): SurfacePolicy {
  return { ...SURFACE_POLICIES[surface] };
}

export function activityTimelineEnabled(flags?: Iterable<string>): boolean {
  if (!flags) return false;
  const enabled = new Set(flags);
  return enabled.has(FOUNDATION_FLAG) && enabled.has(ACTIVITY_TIMELINE_FLAG);
}

function phaseFor(kind: string, hasParent: boolean): ActivityPhase {
  if (kind === "message.user") return "intent";
  if (
    kind === "run.failed" ||
    kind === "delegation.failed" ||
    kind === "budget.exhausted"
  ) {
    return "failure";
  }
  if (
    kind === "run.completed" ||
    kind === "run.cancelled" ||
    kind === "message.assistant" ||
    kind === "delegation.completed"
  ) {
    return "completion";
  }
  if (kind === "delegation.started") return "delegation";
  if (
    kind.startsWith("decision.") ||
    kind.startsWith("approval.") ||
    kind === "mode.changed" ||
    kind === "privacy.notice" ||
    kind === "memory.suppressed" ||
    kind === "memory.retrieval_removed" ||
    kind === "side_effect.blocked"
  )
    return "decision";
  if (
    kind === "tool.result" ||
    kind === "citation.attached" ||
    kind === "artifact.version"
  ) {
    return "evidence";
  }
  if (kind === "run.started" && hasParent) return "delegation";
  return "action";
}

function toneFor(phase: ActivityPhase, kind: string): ActivityTone {
  if (phase === "failure") return "warning";
  if (phase === "completion") return "success";
  if (kind === "approval.requested") return "warning";
  if (phase === "action" || phase === "delegation") return "active";
  return "neutral";
}

function hiddenSummary(kind: string): string {
  if (kind === "tool.call") return "Hermes used a tool";
  if (kind === "tool.result") return "Tool evidence was recorded";
  if (kind === "run.failed")
    return "The run failed; sensitive detail is hidden";
  if (kind === "run.completed") return "The run completed";
  return "Activity recorded; sensitive detail is hidden";
}

function normalizeEvent(
  raw: RawActivityEvent,
  conversationId: string,
  policy: SurfacePolicy,
): ActivityItem | null {
  if (raw.schema !== "hux.event.v1" || !isOpaqueId(raw.id, "evt")) return null;
  if (!Number.isInteger(raw.seq) || (raw.seq as number) < 0) return null;
  if (!isRfc3339Utc(raw.ts) || raw.conversation_id !== conversationId)
    return null;
  if (typeof raw.kind !== "string" || !EVENT_KINDS.has(raw.kind)) return null;
  const redaction = raw.redaction as { level?: unknown } | null;
  const fullyHidden =
    raw.sensitivity === "restricted" || redaction?.level === "full";
  const phase = phaseFor(raw.kind, typeof raw.parent_event_id === "string");
  const references = Array.isArray(raw.evidence) ? raw.evidence : [];
  const evidence = references
    .map((item) => safeEvidenceLabel((item as { kind?: unknown } | null)?.kind))
    .filter((item): item is NonNullable<typeof item> => item !== null)
    .slice(0, policy.evidenceLimit);
  return {
    id: raw.id,
    seq: raw.seq as number,
    timestamp: raw.ts,
    conversationId,
    runId:
      typeof raw.run_id === "string"
        ? safeText(raw.run_id, "", 120) || undefined
        : undefined,
    kind: raw.kind,
    phase,
    tone: toneFor(phase, raw.kind),
    summary: fullyHidden
      ? hiddenSummary(raw.kind)
      : safeText(raw.summary, hiddenSummary(raw.kind)),
    evidence,
    routine: phase === "action" || phase === "evidence",
  };
}

/**
 * Merge reconnect pages without duplicates. Existing sequence owners win;
 * conflicting replay entries are rejected instead of rewriting visible history.
 */
export function mergeActivityEvents(
  existing: readonly ActivityItem[],
  incoming: readonly RawActivityEvent[],
  conversationId: string,
  surface: HuxSurface,
): MergeResult {
  const policy = surfacePolicy(surface);
  const byId = new Map(existing.map((item) => [item.id, item]));
  const bySeq = new Map(existing.map((item) => [item.seq, item]));
  let invalid = 0;
  let replays = 0;
  let conflicts = 0;
  const normalized: ActivityItem[] = [];
  for (const raw of incoming) {
    const item = normalizeEvent(raw, conversationId, policy);
    if (!item) {
      invalid += 1;
      continue;
    }
    normalized.push(item);
  }
  // A reconnect page is not required to preserve transport order. Sorting
  // before conflict resolution makes an initial replay deterministic.
  normalized.sort(
    (left, right) => left.seq - right.seq || left.id.localeCompare(right.id),
  );
  for (const item of normalized) {
    const priorId = byId.get(item.id);
    if (priorId) {
      if (priorId.seq === item.seq) replays += 1;
      else conflicts += 1;
      continue;
    }
    if (bySeq.has(item.seq)) {
      conflicts += 1;
      continue;
    }
    byId.set(item.id, item);
    bySeq.set(item.seq, item);
  }
  const ordered = [...byId.values()].sort(
    (left, right) => left.seq - right.seq || left.id.localeCompare(right.id),
  );
  const afterSeq = ordered.length ? ordered[ordered.length - 1].seq : -1;
  const truncated = Math.max(0, ordered.length - policy.maxItems);
  return {
    items: truncated ? ordered.slice(-policy.maxItems) : ordered,
    afterSeq,
    invalid,
    replays,
    conflicts,
    truncated,
  };
}

export function normalizeCancellationReceipt(
  raw: RawCancellationReceipt,
  surface: HuxSurface,
): CancellationReceipt | null {
  const outcomes = new Set([
    "cancelled",
    "already_complete",
    "failed_to_cancel",
  ]);
  if (raw.schema !== "hux.cancel_receipt.v1" || !isOpaqueId(raw.id, "rcpt"))
    return null;
  if (typeof raw.run_id !== "string" || !isRfc3339Utc(raw.requested_at))
    return null;
  if (typeof raw.outcome !== "string" || !outcomes.has(raw.outcome))
    return null;
  const policy = surfacePolicy(surface);
  const effects = Array.isArray(raw.side_effects) ? raw.side_effects : [];
  const sideEffects = effects
    .slice(0, policy.cancellationEffectLimit)
    .map((value) => {
      const effect = value as {
        description?: unknown;
        reverted?: unknown;
      } | null;
      return {
        description: safeText(
          effect?.description,
          "A side effect was recorded",
          280,
        ),
        reverted: effect?.reverted === true,
      };
    });
  return {
    id: raw.id,
    runId: safeText(raw.run_id, "unknown run", 120),
    requestedAt: raw.requested_at,
    acknowledgedAt: isRfc3339Utc(raw.acknowledged_at)
      ? raw.acknowledged_at
      : undefined,
    completedAt: isRfc3339Utc(raw.completed_at) ? raw.completed_at : undefined,
    outcome: raw.outcome as CancellationReceipt["outcome"],
    sideEffects,
    omittedEffects: Math.max(0, effects.length - sideEffects.length),
  };
}