import type { FastifyInstance } from "fastify";
import type { Db } from "@parking/db";
import { requirePermission } from "../auth.js";
import { reportSummary, type Bucket } from "../reports.js";

// Admin reporting API. Read-only aggregation over the signed ledger (+ the sessions
// cache for durations); no writes, no new event types. Gated on `report:read` — the
// same permission the events feed/occupancy use. See reports.ts, wiki/concepts/reports.md.

const BUCKETS: Bucket[] = ["hour", "day", "month"];

/** Clamp a query into a valid [from, to) + bucket. Defaults: last 30 days, daily. */
function parseQuery(q: { from?: string; to?: string; bucket?: string }): {
  from: string;
  to: string;
  bucket: Bucket;
} {
  const now = Date.now();
  const to = isFiniteIso(q.to) ? q.to! : new Date(now).toISOString();
  const from = isFiniteIso(q.from) ? q.from! : new Date(now - 30 * 86_400_000).toISOString();
  const bucket = BUCKETS.includes(q.bucket as Bucket) ? (q.bucket as Bucket) : "day";
  // Guard the inversion (from after to) — swap rather than return an empty report.
  return from <= to ? { from, to, bucket } : { from: to, to: from, bucket };
}

function isFiniteIso(s: string | undefined): boolean {
  return !!s && Number.isFinite(Date.parse(s));
}

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

  // The whole dashboard in one call: totals, the time series, peak-hour histogram, and
  // subscription stats — aggregated server-side so the SPA just renders. Bucketed in the
  // site timezone. See reports.ts.
  app.get<{ Querystring: { from?: string; to?: string; bucket?: string } }>(
    "/api/reports/summary",
    { preHandler: guard },
    async (req) => reportSummary(db, parseQuery(req.query)),
  );

  // The same series as CSV (one row per bucket) for spreadsheet / accountant export.
  // Amounts are in MAJOR units with 2 decimals here (a CSV is for humans/Excel), unlike
  // the JSON which stays in minor units. text/csv with a download filename.
  app.get<{ Querystring: { from?: string; to?: string; bucket?: string } }>(
    "/api/reports/summary.csv",
    { preHandler: guard },
    async (req, reply) => {
      const summary = reportSummary(db, parseQuery(req.query));
      const lines = [
        "bucket,entries,exits,payments,revenue,cash,card,occupancy_end",
        ...summary.series.map((p) =>
          [
            p.bucket,
            p.entries,
            p.exits,
            p.payments,
            (p.revenueMinor / 100).toFixed(2),
            (p.cashMinor / 100).toFixed(2),
            (p.cardMinor / 100).toFixed(2),
            p.occupancyEnd,
          ].join(","),
        ),
      ];
      reply
        .header("content-type", "text/csv; charset=utf-8")
        .header(
          "content-disposition",
          `attachment; filename="parking-report-${summary.from.slice(0, 10)}_${summary.to.slice(0, 10)}.csv"`,
        )
        .send(lines.join("\n") + "\n");
    },
  );
}