/**
 * GET /api/preview-link?cid=<contactId>
 *   Authorization: Bearer <PREVIEW_ADMIN_TOKEN>
 *
 * Returns a ready-to-send survey URL for a given contact, plus enough
 * context for staff to verify it's the right org. Used for:
 *   - Generating links to paste into ad-hoc emails (or external tools)
 *   - Testing a contact's setup before sending the real CiviCRM email
 *   - QA before rollout
 *
 * AUTH: this mints working form links for ANY contact, so it gets its own
 * secret, PREVIEW_ADMIN_TOKEN, sent as a Bearer header to keep it out of
 * URLs and access logs. Until PREVIEW_ADMIN_TOKEN is set, HEALTH_TOKEN is
 * accepted instead (as a Bearer header or the legacy `?token=`) so the
 * existing support workflow keeps working. With neither set, production
 * returns 404 and development allows passthrough.
 *
 * Returns:
 *   {
 *     contactId, contactName,
 *     orgId, orgName, orgStage,
 *     url,             // the full form URL with cid + cs
 *     checksum,
 *     ttlHours         // how long the checksum is valid (Civi default 14d)
 *   }
 */

import { NextResponse } from "next/server";
import { civi } from "@/lib/civicrm";
import { FORM_CONTACT_RELATIONSHIP } from "@/config/form";
import { appEnv } from "@/lib/env";
import { safeEqual } from "@/lib/staff-token.mjs";

interface PreviewLinkResponse {
  contactId: number;
  contactName: string;
  orgId: number;
  orgName: string;
  orgStage: string;
  url: string;
  checksum: string;
  ttlHours: number;
}

export async function GET(req: Request) {
  const env = appEnv();
  const url = new URL(req.url);
  const cid = url.searchParams.get("cid");
  // Auth gate — see header comment.
  const secret = env.previewAdminToken || env.healthToken;
  if (secret) {
    const bearer = req.headers.get("authorization")?.match(/^Bearer\s+(.+)$/i)?.[1];
    const presented = bearer ?? (env.previewAdminToken ? null : url.searchParams.get("token"));
    if (!presented || !safeEqual(presented, secret)) {
      return new NextResponse("Not Found", { status: 404 });
    }
  } else if (env.isProduction) {
    return new NextResponse("Not Found", { status: 404 });
  }

  if (!cid) {
    return NextResponse.json({ error: "Missing cid parameter." }, { status: 400 });
  }
  const contactId = Number(cid);
  if (!Number.isFinite(contactId)) {
    return NextResponse.json({ error: "cid must be an integer." }, { status: 400 });
  }

  if (env.isStub) {
    return NextResponse.json(
      { error: "Stub mode active — set CIVI_* env vars to generate real links." },
      { status: 501 },
    );
  }

  // Resolve org via the Primary Contact relationship.
  const relRes = await civi<{ contact_id_b: number }>("Relationship", "get", {
    select: ["contact_id_b"],
    where: [
      ["contact_id_a", "=", contactId],
      ["relationship_type_id.name_a_b", "=", FORM_CONTACT_RELATIONSHIP],
      ["is_active", "=", true],
    ],
    limit: 2,
  });
  const orgs = relRes.values ?? [];
  if (orgs.length === 0) {
    return NextResponse.json(
      {
        error: `Contact ${contactId} has no active "${FORM_CONTACT_RELATIONSHIP}" relationship to an organization.`,
      },
      { status: 404 },
    );
  }
  if (orgs.length > 1) {
    return NextResponse.json(
      {
        error: `Contact ${contactId} has multiple active "${FORM_CONTACT_RELATIONSHIP}" relationships. Resolve in CiviCRM first.`,
      },
      { status: 409 },
    );
  }
  const orgId = orgs[0].contact_id_b;

  // Pull contact + org names + the org's current stage so the response gives
  // staff everything they need to confirm "yes, this is the right link."
  const [contactRes, orgRes, csRes] = await Promise.all([
    civi<{ display_name: string }>("Contact", "get", {
      select: ["display_name"],
      where: [["id", "=", contactId]],
    }),
    civi<{ display_name: string; "Food_Co_op_Organizing.Stage": string | null }>("Contact", "get", {
      select: ["display_name", "Food_Co_op_Organizing.Stage"],
      where: [["id", "=", orgId]],
    }),
    civi<{ checksum: string }>("Contact", "getChecksum", { contactId }),
  ]);

  const contactName = contactRes.values?.[0]?.display_name ?? `Contact ${contactId}`;
  const orgName = orgRes.values?.[0]?.display_name ?? `Organization ${orgId}`;
  const orgStage = orgRes.values?.[0]?.["Food_Co_op_Organizing.Stage"] ?? "";
  const checksum = csRes.values?.[0]?.checksum;
  if (!checksum) {
    return NextResponse.json(
      { error: "Could not generate a checksum for this contact." },
      { status: 500 },
    );
  }

  // Build the URL. Prefer the explicit PUBLIC_ORIGIN env var; fall back to
  // the request's own origin (handy for dev / first-deploy).
  const origin =
    env.publicOrigin ?? `${url.protocol}//${url.host}`;
  const formUrl = new URL("/", origin);
  formUrl.searchParams.set("cid", String(contactId));
  formUrl.searchParams.set("cs", checksum);

  const payload: PreviewLinkResponse = {
    contactId,
    contactName,
    orgId,
    orgName,
    orgStage: orgStage ?? "",
    url: formUrl.toString(),
    checksum,
    ttlHours: 14 * 24, // Civi default — adjust if your install changed cs_offset.
  };
  return NextResponse.json(payload);
}