// visitor-event-ingest — admin-side companion to POST /v/event for test
// harness work and manual replay. Takes a single event payload identical
// in shape to what the pixel sends, writes it into the graph against the
// caller's accountId. Not exposed on the public agent surface.

import { getSession } from "../lib/neo4j.js";

export interface IngestParams {
  accountId: string;
  type: "pageview" | "click" | "scroll" | "dwell";
  sessionId: string;
  visitorId: string;
  /** optional Person elementId — overrides identity resolution */
  personId?: string | null;
  url: string;
  path?: string;
  title?: string;
  pageViewId?: string;
  site?: string;
  referrer?: string;
  label?: string;
  href?: string;
  depth?: number;
  dwellMs?: number;
  occurredAt?: string;
}

export interface IngestResult {
  ok: boolean;
  type: string;
  sessionId: string;
}

export async function visitorEventIngest(p: IngestParams): Promise<IngestResult> {
  const session = getSession();
  const occurredAt = p.occurredAt ?? new Date().toISOString();
  try {
    if (p.type === "pageview") {
      await session.run(
        `MERGE (s:Session {accountId: $accountId, sessionId: $sid})
           ON CREATE SET s.startedAt = datetime($occurredAt), s.lastSeenAt = datetime($occurredAt)
           ON MATCH  SET s.lastSeenAt = datetime($occurredAt)
         MERGE (pg:Page {accountId: $accountId, url: $url})
           ON CREATE SET pg.firstSeenAt = datetime($occurredAt), pg.title = $title
         CREATE (pv:PageView {
           accountId: $accountId, pageViewId: $pvId, occurredAt: datetime($occurredAt),
           referrer: $referrer, path: $path
         })
         MERGE (s)-[:HAS_EVENT]->(pv)
         MERGE (pv)-[:OF_PAGE]->(pg)`,
        {
          accountId: p.accountId,
          sid: p.sessionId,
          url: p.url,
          title: p.title ?? "",
          pvId: p.pageViewId ?? `${p.sessionId}_${Date.parse(occurredAt)}`,
          path: p.path ?? "",
          referrer: p.referrer ?? "",
          occurredAt,
        },
      );
    } else if (p.type === "click") {
      await session.run(
        `MERGE (s:Session {accountId: $accountId, sessionId: $sid})
           ON CREATE SET s.startedAt = datetime($occurredAt), s.lastSeenAt = datetime($occurredAt)
           ON MATCH  SET s.lastSeenAt = datetime($occurredAt)
         CREATE (cl:Click {accountId: $accountId, label: $label, href: $href, pageViewId: $pvId, occurredAt: datetime($occurredAt)})
         MERGE (s)-[:HAS_EVENT]->(cl)`,
        {
          accountId: p.accountId,
          sid: p.sessionId,
          label: (p.label ?? "unknown").slice(0, 64),
          href: (p.href ?? "").slice(0, 2048),
          pvId: p.pageViewId ?? "",
          occurredAt,
        },
      );
    } else if (p.type === "scroll") {
      await session.run(
        `MERGE (s:Session {accountId: $accountId, sessionId: $sid})
         MERGE (sm:ScrollMilestone {accountId: $accountId, sessionId: $sid, pageViewId: $pvId})
           ON CREATE SET sm.maxDepth = $depth, sm.firstAt = datetime($occurredAt), sm.lastAt = datetime($occurredAt)
           ON MATCH  SET sm.maxDepth = CASE WHEN sm.maxDepth >= $depth THEN sm.maxDepth ELSE $depth END,
                         sm.lastAt = datetime($occurredAt)
         MERGE (s)-[:HAS_EVENT]->(sm)`,
        { accountId: p.accountId, sid: p.sessionId, pvId: p.pageViewId ?? "", depth: p.depth ?? 0, occurredAt },
      );
    } else if (p.type === "dwell") {
      await session.run(
        `MATCH (pv:PageView {accountId: $accountId, pageViewId: $pvId})
         SET pv.dwellMs = coalesce(pv.dwellMs, 0) + $ms,
             pv.dwellLastAt = datetime($occurredAt)`,
        { accountId: p.accountId, pvId: p.pageViewId ?? "", ms: p.dwellMs ?? 0, occurredAt },
      );
    }

    if (p.personId) {
      await session.run(
        `MATCH (per:Person {accountId: $accountId}) WHERE elementId(per) = $personId
         MATCH (s:Session {accountId: $accountId, sessionId: $sid})
         MERGE (per)-[:VISITED {accountId: $accountId}]->(s)`,
        { accountId: p.accountId, personId: p.personId, sid: p.sessionId },
      );
    } else {
      await session.run(
        `MERGE (av:AnonVisitor {accountId: $accountId, visitorId: $vid})
           ON CREATE SET av.firstSeenAt = datetime($occurredAt), av.lastSeenAt = datetime($occurredAt)
           ON MATCH  SET av.lastSeenAt = datetime($occurredAt)
         WITH av
         MATCH (s:Session {accountId: $accountId, sessionId: $sid})
         MERGE (av)-[:VISITED {accountId: $accountId}]->(s)`,
        { accountId: p.accountId, vid: p.visitorId, sid: p.sessionId, occurredAt },
      );
    }
    return { ok: true, type: p.type, sessionId: p.sessionId };
  } finally {
    await session.close();
  }
}