// app/api/shareholder-changes/parties/route.ts
// GET /api/shareholder-changes/parties?company_id=<id>
//
// Returns the two lists the wizard offers when picking the parties to a share
// transfer. There is no shareholder register yet, so a shareholder is somebody
// already on file — either a person who is (also) a director, or a company:
//
//   { items: {
//       directors: [{ id, name, surname, email, id_no, linked }]  // linked = director of company_id
//       companies: [{ id, name, email, enterprise_no, authorised_shares }]
//   } }
//
// The company being resolved is EXCLUDED from the company list: a company
// cannot be a shareholder in itself, and offering it invites a pointless
// round-trip through validation.
//
// Every director is returned, not only those linked to `company_id`. A
// shareholder of a private company need not serve on its board, and since
// there is no register of who holds what we cannot pre-filter reliably. The
// `linked` flag lets the UI surface the obvious candidates first without
// hiding anyone.

import { NextRequest, NextResponse } from "next/server";
import { fetchCollection, type PBRecord } from "@/lib/pb";
import { COL } from "@/lib/shareholder-changes";

interface DirectorRec extends PBRecord {
  first_names?: string;
  surname?: string;
  email?: string | null;
  id_no?: string | null;
  telephone?: string | null;
}

interface CompanyRec extends PBRecord {
  enterprise_name?: string;
  enterprise_no?: string;
  company_email?: string | null;
  authorised_shares?: number | null;
}

interface JunctionRec extends PBRecord {
  director?: string;
}

export async function GET(req: NextRequest) {
  const url = new URL(req.url);
  const companyId = url.searchParams.get("company_id") ?? "";

  try {
    // Which directors are on the board of the company being resolved. Used only
    // as a "likely current shareholder" hint, so a failure here must not break
    // the picker — degrade to "nobody flagged".
    const linkedDirectorIds = new Set<string>();
    if (companyId) {
      try {
        const junction = await fetchCollection<JunctionRec>(COL.companyDirectors, {
          filter: `company="${companyId}"`,
          perPage: 500,
        });
        for (const j of junction.items) {
          if (j.director) linkedDirectorIds.add(j.director);
        }
      } catch (err) {
        console.error(
          "[shareholder-changes] could not load company directors:",
          err instanceof Error ? err.message : err
        );
      }
    }

    const [directors, companies] = await Promise.all([
      fetchCollection<DirectorRec>(COL.directors, { perPage: 500, sort: "surname" }),
      fetchCollection<CompanyRec>(COL.companies, {
        perPage: 500,
        sort: "enterprise_name",
      }),
    ]);

    // A company with no name is a data-quality artefact, not a pickable party.
    const companyItems = companies.items
      .filter((c) => (c.enterprise_name ?? "").trim() !== "")
      .filter((c) => c.id !== companyId)
      .map((c) => ({
        id: c.id,
        name: (c.enterprise_name ?? "").trim(),
        email: (c.company_email ?? "").trim() || null,
        enterprise_no: c.enterprise_no ?? null,
        authorised_shares: c.authorised_shares ?? null,
      }));

    const directorItems = directors.items
      .filter((d) => [d.first_names, d.surname].some((v) => (v ?? "").trim() !== ""))
      .map((d) => ({
        id: d.id,
        name: (d.first_names ?? "").trim(),
        surname: (d.surname ?? "").trim(),
        email: (d.email ?? "").trim() || null,
        id_no: d.id_no ?? null,
        // Carried into the signature block ("Cell - 0827985409"), matching how
        // section 4 identifies its signers.
        telephone: (d.telephone ?? "").trim() || null,
        linked: linkedDirectorIds.has(d.id),
      }));

    return NextResponse.json({
      items: {
        directors: directorItems,
        companies: companyItems,
      },
    });
  } catch (err) {
    return NextResponse.json(
      { error: err instanceof Error ? err.message : "Unexpected error" },
      { status: 500 }
    );
  }
}