parking_solution/apps/server/src/routes/snapshots.ts

import type { FastifyInstance } from "fastify";
import { and, desc, eq, deviceEvents, snapshots, type Db } from "@parking/db";
import { requirePermission } from "../auth.js";

// Read access to captured entry/exit snapshots (the BLOB-in-DB image store, see
// packages/db schema + wiki/concepts/lane-direction.md). Snapshots are evidence
// tied to a signed vehicle_entry/exit by `identity`; the operator reviews them
// next to the event. Read-only — images are written only by the flows (snapshot.ts),
// never via the API.

export async function snapshotRoutes(app: FastifyInstance, db: Db): Promise<void> {
  const guard = requirePermission("session:read");

  // Snapshot metadata for one session/credential identity (NOT the bytes), newest
  // first — lets the UI show "entry/exit image" links beside an event. We also return
  // FAILED capture attempts (from snapshot telemetry) so the operator can tell a
  // camera that was offline from a direction that simply has no camera — otherwise a
  // missing shot is a silent gap. See snapshot.ts (recordFailure).
  app.get<{ Params: { identity: string } }>(
    "/api/snapshots/by-identity/:identity",
    { preHandler: guard },
    async (req) => {
      const identity = req.params.identity;
      const rows = db
        .select({
          id: snapshots.id,
          direction: snapshots.direction,
          deviceId: snapshots.deviceId,
          identity: snapshots.identity,
          contentType: snapshots.contentType,
          capturedAt: snapshots.capturedAt,
        })
        .from(snapshots)
        .where(eq(snapshots.identity, identity))
        .orderBy(desc(snapshots.capturedAt))
        .all();

      // Failed attempts: kind="snapshot" telemetry whose detail.identity matches and
      // detail.ok === false. There may be both a failure and (on a retry) a success
      // for the same direction; we keep only failures with NO successful shot in the
      // same direction, so a recovered capture doesn't show a stale warning.
      const haveDir = new Set<string | null>(rows.map((r) => r.direction));
      const telemetry = db
        .select({ detail: deviceEvents.detail, deviceId: deviceEvents.deviceId, occurredAt: deviceEvents.occurredAt })
        .from(deviceEvents)
        .where(and(eq(deviceEvents.category, "camera"), eq(deviceEvents.kind, "snapshot")))
        .orderBy(desc(deviceEvents.occurredAt))
        .all();
      const failures: {
        direction: "entry" | "exit" | null;
        deviceId: string;
        error: string;
        occurredAt: string;
      }[] = [];
      const seenFailDir = new Set<string>();
      for (const row of telemetry) {
        const d = (row.detail ?? {}) as { identity?: string; ok?: boolean; error?: string; direction?: string };
        if (d.identity !== identity || d.ok !== false) continue;
        const dir = d.direction === "entry" || d.direction === "exit" ? d.direction : null;
        const dirKey = dir ?? "both";
        if (haveDir.has(dir) || seenFailDir.has(dirKey)) continue; // a success exists, or already shown
        seenFailDir.add(dirKey);
        failures.push({
          direction: dir,
          deviceId: row.deviceId ?? "",
          error: d.error ?? "capture failed",
          occurredAt: row.occurredAt ?? "",
        });
      }

      // Recognized PLATES for this session: kind="read" telemetry from the ANPR-on-
      // snapshot path (snapshot.ts → recognizePlate). Advisory — a record of the plate
      // observed for the session, shown beside the image. Newest first.
      const plateRows = db
        .select({ detail: deviceEvents.detail, occurredAt: deviceEvents.occurredAt })
        .from(deviceEvents)
        .where(and(eq(deviceEvents.category, "camera"), eq(deviceEvents.kind, "read")))
        .orderBy(desc(deviceEvents.occurredAt))
        .all();
      const plates: {
        plate: string;
        confidence: number | null;
        region: string | null;
        direction: "entry" | "exit" | null;
        snapshotId: string | null;
        at: string;
      }[] = [];
      for (const row of plateRows) {
        const d = (row.detail ?? {}) as {
          identity?: string;
          plate?: string;
          confidence?: number;
          region?: string | null;
          direction?: string;
          snapshotId?: string;
        };
        if (d.identity !== identity || !d.plate) continue;
        plates.push({
          plate: d.plate,
          confidence: typeof d.confidence === "number" ? d.confidence : null,
          region: d.region ?? null,
          direction: d.direction === "entry" || d.direction === "exit" ? d.direction : null,
          snapshotId: d.snapshotId ?? null,
          at: row.occurredAt ?? "",
        });
      }

      return { snapshots: rows, failures, plates };
    },
  );

  // Stream one snapshot's image bytes by id. Returns the stored content type.
  app.get<{ Params: { id: string } }>(
    "/api/snapshots/:id",
    { preHandler: guard },
    async (req, reply) => {
      const row = db.select().from(snapshots).where(eq(snapshots.id, req.params.id)).get();
      if (!row) return reply.code(404).send({ error: "no such snapshot" });
      reply.header("content-type", row.contentType);
      reply.header("cache-control", "private, max-age=31536000, immutable");
      return reply.send(row.bytes);
    },
  );
}