/**
 * v1.9.0 — single-metric period-over-period range read.
 *
 * `GET /api/analytics/range?type=<MeasurementType>&range=7d|30d|90d|1y`
 * returns the current-window aggregate, the previous comparable window, and
 * the composed delta. Single metric type by construction — the Insights
 * metric page is single-metric — so the read is one
 * `readBestGranularityRollups` covering the trailing `2N` days, sliced into
 * the two halves. No per-type fan-out, no Prisma-pool burst (the opposite of
 * the deleted 15-way live walk).
 *
 * The cached `/api/analytics?slice=summaries` slice is deliberately left
 * untouched: adding a range dimension to its single shared cache key would
 * fragment the hottest cache on the dashboard. This dedicated route carries
 * its own per-(type, range) cache slot on the client (`queryKeys.analyticsRange`).
 *
 * iOS-safe: additive new route, no change to the `/api/analytics` envelope.
 */
import { NextRequest } from "next/server";
import { z } from "zod/v4";

import { apiHandler, requireAuth } from "@/lib/api-handler";
import { apiSuccess, returnAllZodIssues } from "@/lib/api-response";
import { annotate } from "@/lib/logging/context";
import { measurementTypeEnum } from "@/lib/validations/measurement";
import {
  ANALYTICS_RANGES,
  computeRangeDelta,
  type AnalyticsRange,
} from "@/lib/analytics/range-delta";
import type { MeasurementType } from "@/generated/prisma/client";

export const dynamic = "force-dynamic";

const rangeQuerySchema = z.object({
  type: measurementTypeEnum,
  range: z.enum(ANALYTICS_RANGES),
});

export const GET = apiHandler(async (request: NextRequest) => {
  const { user } = await requireAuth();

  const parsed = rangeQuerySchema.safeParse({
    type: request.nextUrl.searchParams.get("type"),
    range: request.nextUrl.searchParams.get("range"),
  });
  if (!parsed.success) {
    annotate({
      action: { name: "analytics.range.invalid-params" },
      meta: { issue_count: parsed.error.issues.length },
    });
    return returnAllZodIssues(parsed.error, 422);
  }

  const type = parsed.data.type as MeasurementType;
  const range = parsed.data.range as AnalyticsRange;

  const result = await computeRangeDelta(user.id, type, range);

  annotate({
    action: { name: "analytics.range.read" },
    meta: {
      type,
      range,
      granularity: result.granularity,
      current_count: result.current.count,
      previous_count: result.previous.count,
    },
  });

  return apiSuccess(result);
});