/**
 * Server-side helpers for the /deliveries page.
 *
 * Two operations:
 *   1. `loadItems` — bulk flip `invoiced → with_driver` and stamp
 *      `loaded_at` to now. Used by the "To Load" tab.
 *   2. `checkInItems` — bulk flip `with_driver → checked_in`,
 *      write the typed `delivery_reference`, and stamp
 *      `checked_in_at` + `checked_in_by` (current authed user).
 *      Used by the "Back from Driver" tab.
 *
 * Both are tolerant: an item that's already in the target state is
 * silently skipped (idempotent on retry), and an item that's in an
 * unexpected source state is also skipped + reported in the result's
 * `skipped` array. The UI uses the skipped list to surface a
 * "some items couldn't be moved" toast so the operator can re-check.
 *
 * Why a service module instead of inline route logic: the bulk
 * update is a non-trivial loop over `pb.collection().update()` per
 * id — a single 500 from one bad row would otherwise abort the
 * whole batch. Centralising the loop lets us add per-row error
 * handling + a structured result without bloating the route file.
 */
import { getAdminPocketBase } from "./pocketbase-admin";
import { getOrderItemsCollectionName } from "./orders-service";
import type { DeliveryNote } from "@/lib/types";

const DELIVERY_NOTES = "delivery_notes";

export type DeliveryListTab = "to_load" | "back_from_driver" | "checked_in";

/**
 * The PB item_status values each tab filters on.
 *
 *   to_load            → invoiced (waiting for warehouse to load)
 *   back_from_driver   → with_driver (driver brought the paper back,
 *                        operator needs to type the reference)
 *   checked_in         → checked_in (operator verified, waiting for
 *                        n8n to upload the signed copy + flip to
 *                        `completed`)
 *
 * `completed` is intentionally NOT a tab here — those items are
 * considered "done" and the office doesn't need to act on them.
 * The 4th state will get its own tab once the n8n workflow ships.
 */
export const TAB_TO_ITEM_STATUS: Record<DeliveryListTab, string[]> = {
  to_load: ["invoiced"],
  back_from_driver: ["with_driver"],
  checked_in: ["checked_in"],
};

/**
 * The PB delivery_notes.status values each tab filters on for the
 * DN rows. The DN paper tracks the same three stops as the items,
 * with `draft` added to the To Load tab so every DN that hasn't
 * been invoiced surfaces on /deliveries (the operator's request):
 *
 *   to_load            → draft, sent
 *                                     (paper on the desk; needs to
 *                                      be sent + loaded for driver)
 *   back_from_driver   → loaded, po_received
 *                                     (paper is with the driver —
 *                                      either on the way out or
 *                                      back with the customer PO;
 *                                      signed copy still pending)
 *   checked_in         → invoiced     (invoice was created; signed
 *                                     copy still pending)
 *
 * `invoiced` is excluded from the To Load tab — once the invoice
 * is created, the DN shows on the Checked In tab instead. Items
 * take over from there. `completed` (signed copy received) is
 * excluded everywhere — same reason completed items are excluded.
 * `cancelled` is excluded everywhere too: those DNs are out of
 * office scope.
 */
export const TAB_TO_DN_STATUS: Record<DeliveryListTab, string[]> = {
  to_load: ["draft", "sent"],
  back_from_driver: ["loaded", "po_received"],
  checked_in: ["invoiced"],
};

export function isDeliveryListTab(s: string): s is DeliveryListTab {
  return s === "to_load" || s === "back_from_driver" || s === "checked_in";
}

export type DeliveryListResult = {
  items: Array<{
    id: string;
    description: string;
    quantity: number | null;
    selling_price: number | null;
    cost_price: number | null;
    item_status: string;
    delivery_reference: string | null;
    /**
     * Human-readable DN id (e.g. `DN26091405`) this item
     * belongs to. The /deliveries page's DN expand panel
     * joins on this field against each delivery note's
     * `delivery_note_number`. The PB schema's relation
     * field `delivery_note` exists but nothing writes to
     * it; the text column is the actual join key.
     */
    delivery_note_number: string | null;
    /**
     * QuickBooks invoice number, extracted from the nested
     * `order_item_details.invoice.number` JSON. Null for rows
     * that haven't been through the QB invoicing flow yet
     * (older rows, or counter-pickup ad-hoc items that were
     * never sent to QB).
     */
    invoice_number: string | null;
    loaded_at: string | null;
    checked_in_at: string | null;
    order: {
      id: string;
      order_number: string;
      customer_id: string;
      customer_name: string | null;
      company_id: string;
      company_name: string | null;
    } | null;
    checked_in_by: { id: string; name?: string; email?: string } | null;
  }>;
  /**
   * Delivery-note rows that ride the same tab mapping as the items
   * (sent / po_received / invoiced → to_load / back_from_driver /
   * checked_in). The operator needs to track the signed-copy return
   * for every DN whose paper is out — that's the whole reason this
   * surface exists on /deliveries.
   */
  delivery_notes: Array<{
    id: string;
    delivery_note_number: string;
    status: string;
    customer_po: string | null;
    delivery_date: string | null;
    signed_copy: string[] | null;
    order: {
      id: string;
      order_number: string;
      customer_id: string;
      customer_name: string | null;
      company_id: string;
      company_name: string | null;
    } | null;
  }>;
  /**
   * Items linked to the page's DNs regardless of `item_status`.
   * Feeds the DN expand panel so it shows every item on the DN
   * (same scope as the full /delivery-notes/{id} page). The
   * main items list on the page uses `items` only — `dn_items`
   * is never rendered as a top-level row.
   */
  dn_items: Array<{
    id: string;
    description: string;
    quantity: number | null;
    selling_price: number | null;
    cost_price: number | null;
    item_status: string;
    delivery_reference: string | null;
    delivery_note_number: string | null;
    invoice_number: string | null;
    loaded_at: string | null;
    checked_in_at: string | null;
    order: {
      id: string;
      order_number: string;
      customer_id: string;
      customer_name: string | null;
      company_id: string;
      company_name: string | null;
    } | null;
    checked_in_by: { id: string; name?: string; email?: string } | null;
  }>;
  totalItems: number;
  totalDeliveryNotes: number;
  page: number;
  perPage: number;
  totalPages: number;
};

/**
 * Load the order_items for one of the three tabs, with the
 * expanded order (number + company + customer id) and the
 * operator who checked the item in (for the Checked In tab).
 *
 * Why we return a flat list instead of pre-grouping by customer:
 * the client already has the orders / customers collections loaded
 * for the dashboard; grouping on the client keeps the server
 * response shape simple + lets the operator re-sort the page
 * without a round trip.
 */
export async function listDeliveryItems(params: {
  tab: DeliveryListTab;
  page?: number;
  perPage?: number;
  search?: string;
}): Promise<DeliveryListResult> {
  const pb = await getAdminPocketBase();
  const page = params.page || 1;
  const perPage = params.perPage || 200; // one page covers the
                                          // office for a full week
                                          // in practice
  const statuses = TAB_TO_ITEM_STATUS[params.tab];
  const statusFilter = statuses
    .map((s) => `item_status = "${s}"`)
    .join(" || ");

  // The order_items.order relation is optional as of the
  // 2026-07-19-delivery-notes-v3 migration (ad-hoc counter-pickup
  // rows have no parent order). We still want those rows on the
  // page — they came off the shelf with no order backing them,
  // and they still need to be loaded for the customer. So we
  // DON'T filter on `order != ""` here.
  //
  // Search: a single search box hits everything the office
  // might type. The fields covered are split between server-side
  // (where PB's filter can reach them) and client-side (where
  // the join is too deep for PB to filter on directly):
  //
  //   Server-side (PB filter):
  //     - `description`              — text, `~` substring
  //     - `order_item_details.invoice.number`
  //                                  — JSON path, `~` substring;
  //                                    the QB invoice number is
  //                                    nested inside the
  //                                    `order_item_details` JSON
  //                                    column. PB's dot-notation
  //                                    filter handles it.
  //     - `selling_price`            — number, exact match.
  //                                    Activated only when the
  //                                    search string parses as a
  //                                    number (see below).
  //     - `cost_price`               — number, exact match.
  //
  //   Client-side (the page filters again after fetch):
  //     - `order.order_number`       — 2nd-level expand; PB can't
  //                                    filter on it directly in
  //                                    this version. The page
  //                                    does a case-insensitive
  //                                    `includes` over the
  //                                    already-fetched rows.
  //     - `order.customer.customer`  — same reason. The customer
  //                                    name is on the `customers`
  //                                    collection, 2 relations
  //                                    deep from order_items.
  //
  // Why not push everything to the server: PB's `~` on JSON
  // paths and numbers works fine, but it can't reach across
  // 2 expanded relations. A `getList(200)` then a 5ms in-memory
  // filter is the same wire cost as a complex server filter that
  // PB might not be able to plan an index for.
  const search = (params.search || "").trim();
  let searchFilter = "";
  if (search) {
    const q = search.replace(/"/g, '\\"');
    // PB `~` is case-insensitive for ASCII; for our purposes
    // (descriptions are mostly English / numbers) that's fine.
    const textClauses = [
      `description ~ "${q}"`,
      // The invoice number lives in the `order_item_details`
      // JSON column. PB's dot-notation filter lets us reach
      // it without expanding a relation.
      `order_item_details.invoice.number ~ "${q}"`,
    ];

    // If the search string parses cleanly as a number, also
    // match `selling_price` and `cost_price` exactly. We use
    // `=` (not `~`) because PB's number filter doesn't support
    // substring — "120" matches 120.0 but not 120.50. That's
    // intentional: a partial number match would be confusing
    // (typing "1" would match 100s of lines).
    //
    // parseFloat is permissive ("12.5abc" → 12.5); we
    // additionally check that the entire string is a valid
    // number via the regex. This avoids `selling_price = 12.5`
    // when the user typed "12.5 boxes" — the regex rejects it
    // and we skip the price match.
    const numericMatch = search.match(/^-?\d+(\.\d+)?$/);
    if (numericMatch) {
      textClauses.push(`selling_price = ${search}`);
      textClauses.push(`cost_price = ${search}`);
    }

    searchFilter = `(${textClauses.join(" || ")})`;
  }

  const filter = searchFilter
    ? `(${statusFilter}) && ${searchFilter}`
    : `(${statusFilter})`;

  // Two parallel queries: items (existing flow) + delivery_notes
  // (the new signed-copy tracking). PB doesn't have a UNION, so
  // we run both and merge in the service. `Promise.all` keeps
  // the latency at the slower of the two rather than summing.
  //
  // The DN query has its own server-side filter so the search box
  // can find DNs by delivery_note_number / customer_po too — same
  // trade-off as the items query: PB can reach text fields on the
  // root collection but not 2nd-level expanded joins, so the
  // remaining order / customer / company name filtering happens
  // client-side in the page.
  const dnStatuses = TAB_TO_DN_STATUS[params.tab];
  const dnStatusFilter = dnStatuses
    .map((s) => `status = "${s}"`)
    .join(" || ");
  let dnSearchFilter = "";
  if (search) {
    const q = search.replace(/"/g, '\\"');
    const dnTextClauses = [
      `delivery_note_number ~ "${q}"`,
      `customer_po ~ "${q}"`,
    ];
    dnSearchFilter = `(${dnTextClauses.join(" || ")})`;
  }
  const dnFilter = dnSearchFilter
    ? `(${dnStatusFilter}) && ${dnSearchFilter}`
    : `(${dnStatusFilter})`;

  const [itemsResult, dnsResult] = await Promise.all([
    pb.collection(getOrderItemsCollectionName()).getList(page, perPage, {
      filter,
      sort: "-updated",
      // `order.customer` and `order.company` are 2nd-level
      // expands: we want the order header's customer/company
      // relations resolved in the same fetch so the page can
      // render "Customer X — Order ORD-..." without a second
      // round trip per row. PB's expand syntax is dot-separated
      // paths; commas separate siblings.
      //
      // IMPORTANT: when `fields=` is set, PB also whitelists
      // top-level response keys — and the `expand` block is a
      // top-level key. If the expanded relation isn't added to
      // the whitelist (as `expand.<path>`), PB silently drops the
      // whole `expand` object. Without `expand.order` here, every
      // row comes back with `r.expand` undefined and the page
      // falls into its "(NO ORDER) / Counter pickup" bucket for
      // all items. Verified live against PB 2026-08-12.
      expand: "order.customer,order.company,checked_in_by",
      fields:
        "id,description,quantity,unit,selling_price,cost_price,item_status,delivery_reference," +
        // `delivery_note_number` is the human-readable DN id (e.g.
        // `DN26091405`). The PB schema also has a relation field
        // `delivery_note` but nothing currently writes to it — the
        // join key everywhere else (the full DN detail page, the
        // delivery-notes service) is the text column. We only
        // request the column that's actually populated.
        "delivery_note_number,loaded_at,checked_in_at,checked_in_by,order,updated,order_item_details," +
        "expand.order,expand.order.customer,expand.order.company,expand.checked_in_by",
    }),
    pb.collection(DELIVERY_NOTES).getList(page, perPage, {
      filter: dnFilter,
      sort: "-updated",
      expand: "order.customer,order.company",
      fields:
        "id,delivery_note_number,status,customer_po,delivery_date,signed_copy," +
        "order,updated,expand.order,expand.order.customer,expand.order.company",
    }),
  ]);

  // Query #3 — every order_item that has a `delivery_note_number`
  // set to one of the DNs in this response, regardless of the
  // item's own `item_status`. The DN expand panel needs these so
  // it can show every item on the DN — same scope as the full
  // /delivery-notes/{id} page (which joins by `delivery_note_number`
  // without filtering on item_status). Without this, a DN whose
  // items are still in `delivery_note` status (paper sent, invoice
  // not yet created) shows "no items loaded" on the expand panel
  // even though the same DN has items on the full detail page.
  // The main items list (query #1) is what drives the page-level
  // bulk actions; this third query only feeds the per-DN expand
  // panel — so its status-unfiltered scope doesn't leak into the
  // bulk-action rows. Runs after the first two so we have the DN
  // numbers in hand; the wire cost is one extra PB read on top
  // of the first two parallel queries.
  //
  // PB rejects filter strings longer than ~8 KB. ~40 chars per
  // `delivery_note_number = "DN..." || ` — 200 candidates keeps
  // us under the limit. Same pattern as
  // order-delivery-note-link-service.ts.
  const dnNumbers = (dnsResult.items as unknown as Array<{ delivery_note_number?: string }>)
    .map((d) => d.delivery_note_number)
    .filter((n): n is string => typeof n === "string" && n.length > 0);
  let dnItemsResult: { items: Array<Record<string, unknown>>; totalItems: number } = {
    items: [],
    totalItems: 0,
  };
  if (dnNumbers.length > 0) {
    const batch = dnNumbers.slice(0, 200);
    const dnItemsFilter = batch
      .map((n) => `delivery_note_number = "${n.replace(/"/g, '\\"')}"`)
      .join(" || ");
    dnItemsResult = (await pb
      .collection(getOrderItemsCollectionName())
      .getList(1, perPage, {
        filter: dnItemsFilter,
        sort: "-updated",
        expand: "order.customer,order.company",
        fields:
          "id,description,quantity,unit,selling_price,cost_price,item_status,delivery_reference," +
          "delivery_note_number,loaded_at,checked_in_at,checked_in_by,order,updated,order_item_details," +
          "expand.order,expand.order.customer,expand.order.company",
      })) as unknown as { items: Array<Record<string, unknown>>; totalItems: number };
  }

  type Row = {
    id: string;
    description: string;
    quantity: number | null;
    selling_price: number | null;
    cost_price: number | null;
    item_status: string;
    delivery_reference: string | null;
    /**
     * Human-readable DN id (e.g. `DN26091405`). The /deliveries
     * page's DN expand panel uses this to filter the items that
     * belong to a given DN — the same join key the full DN detail
     * page uses (see `pb-helpers.getDeliveryNoteItems`). The
     * relation field `delivery_note` in the schema is never
     * populated; this is the column we actually care about.
     */
    delivery_note_number: string | null;
    unit: string | null;
    loaded_at: string | null;
    checked_in_at: string | null;
    checked_in_by: string | null;
    order: string | null;
    updated: string;
    /**
     * JSON column. The shape is `{ invoice: { number, date, ... },
     * print: { ... } }` — only the invoice.number is read for the
     * /deliveries page. Defensive-typed as `unknown` because PB
     * returns whatever the operator / n8n wrote; a missing or
     * malformed JSON should never crash the page.
     */
    order_item_details?: unknown;
    expand?: {
      order?: {
        id: string;
        order_number: string;
        company: string;
        customer: string;
        expand?: {
          customer?: { id: string; customer?: string };
          company?: { id: string; company?: string };
        };
      };
      checked_in_by?: { id: string; name?: string; email?: string };
    };
  };

  // Read the QB invoice number from the nested JSON. The shape
  // is `order_item_details.invoice.number` — we tolerate missing
  // keys at every level because older rows (pre-QB-integration)
  // don't have it, and the page renders "—" in that case.
  function readInvoiceNumber(details: unknown): string | null {
    if (!details || typeof details !== "object") return null;
    const inv = (details as { invoice?: unknown }).invoice;
    if (!inv || typeof inv !== "object") return null;
    const n = (inv as { number?: unknown }).number;
    return typeof n === "string" && n.length > 0 ? n : null;
  }

  const mapRow = (r: Row) => ({
    id: r.id,
    description: r.description ?? "",
    quantity: r.quantity ?? null,
    selling_price: r.selling_price ?? null,
    cost_price: r.cost_price ?? null,
    item_status: r.item_status,
    delivery_reference: r.delivery_reference ?? null,
    delivery_note_number: r.delivery_note_number ?? null,
    unit: r.unit ?? null,
    invoice_number: readInvoiceNumber(r.order_item_details),
    loaded_at: r.loaded_at ?? null,
    checked_in_at: r.checked_in_at ?? null,
    order: r.expand?.order
      ? {
          id: r.expand.order.id,
          order_number: r.expand.order.order_number,
          // Customer + company names. `customer` / `company` on the
          // order row is the relation id; the expand gives us the
          // record. We use `?.customer` (singular) because that's
          // the field name on the `customers` collection (not
          // `name`). Same for `companies.company`. Ad-hoc rows
          // (no parent order) get nulls and the page renders
          // "Counter pickup" or similar.
          customer_id: r.expand.order.customer,
          customer_name: r.expand.order.expand?.customer?.customer ?? null,
          company_id: r.expand.order.company,
          company_name: r.expand.order.expand?.company?.company ?? null,
        }
      : null,
    checked_in_by: r.expand?.checked_in_by
      ? {
          id: r.expand.checked_in_by.id,
          name: r.expand.checked_in_by.name,
          email: r.expand.checked_in_by.email,
        }
      : null,
  });

  const items = (itemsResult.items as unknown as Row[]).map(mapRow);

  // Map the third query (DN-linked items, any status) through the
  // same mapper. Deduped by item id so the per-DN expand panel
  // doesn't render the same row twice when an item already
  // appears in `items` (status-filtered) AND `dn_items`
  // (DN-linked, any status). A `Map` keyed by item id preserves
  // the first occurrence — the status-filtered one, which is the
  // version the page renders in the main list. The expand panel
  // looks up by item id via `dnItemsById` and never sees a dup.
  const dnItemsRaw = (dnItemsResult.items as unknown as Row[]).map(mapRow);
  const dnItemsById = new Map<string, (typeof dnItemsRaw)[number]>();
  for (const it of items) dnItemsById.set(it.id, it);
  for (const it of dnItemsRaw) if (!dnItemsById.has(it.id)) dnItemsById.set(it.id, it);
  const dn_items = [...dnItemsById.values()];

  // Map DN rows. The expand shape mirrors the items query so the
  // page can group both row kinds by customer → order with the
  // same renderer.
  type DNRow = {
    id: string;
    delivery_note_number: string;
    status: string;
    customer_po: string | null;
    delivery_date: string | null;
    signed_copy: string[] | null;
    order: string | null;
    expand?: {
      order?: {
        id: string;
        order_number: string;
        company: string;
        customer: string;
        expand?: {
          customer?: { id: string; customer?: string };
          company?: { id: string; company?: string };
        };
      };
    };
  };

  const delivery_notes = (dnsResult.items as unknown as DNRow[]).map((r) => ({
    id: r.id,
    delivery_note_number: r.delivery_note_number ?? "",
    status: r.status,
    customer_po: r.customer_po ?? null,
    delivery_date: r.delivery_date ?? null,
    signed_copy: r.signed_copy ?? null,
    order: r.expand?.order
      ? {
          id: r.expand.order.id,
          order_number: r.expand.order.order_number,
          customer_id: r.expand.order.customer,
          customer_name: r.expand.order.expand?.customer?.customer ?? null,
          company_id: r.expand.order.company,
          company_name: r.expand.order.expand?.company?.company ?? null,
        }
      : null,
  }));

  return {
    items,
    delivery_notes,
    /**
     * Items linked to the page's DNs regardless of `item_status`.
     * Feeds the DN expand panel so it shows every item on the
     * DN (same scope as the full /delivery-notes/{id} page).
     * The main items list on the page uses `items` only — this
     * field is never rendered as a top-level row.
     */
    dn_items,
    totalItems: itemsResult.totalItems,
    totalDeliveryNotes: dnsResult.totalItems,
    page: itemsResult.page,
    perPage: itemsResult.perPage,
    totalPages: itemsResult.totalPages,
  };
}

export type LoadResult = {
  loaded: string[];
  skipped: Array<{ id: string; reason: string }>;
};

const MAX_BATCH = 200;

/**
 * Bulk flip `invoiced → with_driver` and stamp `loaded_at = now()`.
 * Used by the "To Load" tab's "Load N selected" buttons.
 *
 * Idempotent on the source state: an item that's already
 * `with_driver` (or anything else other than `invoiced`) is skipped
 * with a `reason` instead of being moved. This makes the call safe
 * to retry on a flaky network without double-stamping `loaded_at`.
 *
 * We do not enforce a single source state for the whole batch — if
 * the operator checks 5 items and 1 of them is already in
 * `with_driver`, we move the 4 and report the 1. The UI uses the
 * `skipped` array to surface "4 loaded, 1 was already with the
 * driver — skipped" so the operator can re-check.
 */
export async function loadItems(itemIds: string[]): Promise<LoadResult> {
  const pb = await getAdminPocketBase();
  const collection = getOrderItemsCollectionName();

  if (itemIds.length === 0) {
    return { loaded: [], skipped: [] };
  }
  if (itemIds.length > MAX_BATCH) {
    throw new Error(`Too many items in one batch (${itemIds.length} > ${MAX_BATCH}).`);
  }

  // Snapshot the source state per id so we don't read+write the
  // same row from the loop (PB will return the post-update value
  // otherwise). The `fields` param keeps the fetch cheap.
  const orFilter = itemIds.map((id) => `id="${id}"`).join(" || ");
  const rows = await pb.collection(collection).getFullList<{
    id: string;
    item_status: string;
  }>({
    filter: orFilter,
    fields: "id,item_status",
  });
  const stateById = new Map<string, string>();
  for (const r of rows) stateById.set(r.id, r.item_status);

  const loaded: string[] = [];
  const skipped: Array<{ id: string; reason: string }> = [];
  const now = new Date().toISOString();

  for (const id of itemIds) {
    const current = stateById.get(id);
    if (current === undefined) {
      skipped.push({ id, reason: "Item not found" });
      continue;
    }
    if (current !== "invoiced") {
      skipped.push({
        id,
        reason: `Expected item_status=invoiced, found ${current || "empty"}`,
      });
      continue;
    }
    try {
      await pb.collection(collection).update(id, {
        item_status: "with_driver",
        loaded_at: now,
      });
      loaded.push(id);
    } catch (err) {
      skipped.push({
        id,
        reason: err instanceof Error ? err.message : "Update failed",
      });
    }
  }

  return { loaded, skipped };
}

export type CheckInInput = {
  itemIds: string[];
  /**
   * The invoice/DN number from the signed paper. Trimmed +
   * length-checked (1..64 chars to match the schema max). Empty
   * strings are rejected — the whole batch fails if the operator
   * submits an empty reference.
   */
  reference: string;
  /**
   * The authed user id who typed the reference. Required: the
   * `checked_in_by` field on the item is a relation, not a free-
   * text audit. We pull this from the PocketBase auth record on
   * the request, not the body, so the client can't spoof another
   * user.
   */
  checkedInByUserId: string;
};

export type CheckInResult = {
  checkedIn: string[];
  skipped: Array<{ id: string; reason: string }>;
};

/**
 * Bulk flip `with_driver → checked_in`, write the reference, and
 * stamp `checked_in_at` + `checked_in_by`. Used by the "Back from
 * Driver" tab.
 *
 * Reference handling: trimmed. Empty/whitespace-only references
 * fail the whole batch with a single clear error. We don't try
 * to "be clever" with auto-generated fallback refs — the operator
 * is the one who has the paper in their hand, and a wrong
 * reference is worse than a rejected batch.
 *
 * Idempotency: items already in `checked_in` are skipped with a
 * reason rather than re-stamped. This means a partial network
 * failure mid-batch can be retried — already-checked-in items
 * stay checked in, the rest get the new reference + timestamp.
 */
export async function checkInItems(
  input: CheckInInput
): Promise<CheckInResult> {
  const ref = (input.reference || "").trim();
  if (ref.length === 0) {
    throw new Error("Reference cannot be empty.");
  }
  if (ref.length > 64) {
    throw new Error("Reference is too long (max 64 chars).");
  }
  if (input.itemIds.length === 0) {
    return { checkedIn: [], skipped: [] };
  }
  if (input.itemIds.length > MAX_BATCH) {
    throw new Error(`Too many items in one batch (${input.itemIds.length} > ${MAX_BATCH}).`);
  }

  const pb = await getAdminPocketBase();
  const collection = getOrderItemsCollectionName();

  const orFilter = input.itemIds.map((id) => `id="${id}"`).join(" || ");
  const rows = await pb.collection(collection).getFullList<{
    id: string;
    item_status: string;
  }>({
    filter: orFilter,
    fields: "id,item_status",
  });
  const stateById = new Map<string, string>();
  for (const r of rows) stateById.set(r.id, r.item_status);

  const checkedIn: string[] = [];
  const skipped: Array<{ id: string; reason: string }> = [];
  const now = new Date().toISOString();

  for (const id of input.itemIds) {
    const current = stateById.get(id);
    if (current === undefined) {
      skipped.push({ id, reason: "Item not found" });
      continue;
    }
    if (current !== "with_driver") {
      skipped.push({
        id,
        reason: `Expected item_status=with_driver, found ${current || "empty"}`,
      });
      continue;
    }
    try {
      await pb.collection(collection).update(id, {
        item_status: "checked_in",
        delivery_reference: ref,
        checked_in_at: now,
        checked_in_by: input.checkedInByUserId,
      });
      checkedIn.push(id);
    } catch (err) {
      skipped.push({
        id,
        reason: err instanceof Error ? err.message : "Update failed",
      });
    }
  }

  return { checkedIn, skipped };
}


export type SignedCopyInput = {
  deliveryNoteId: string;
  file: File;
};

export type SignedCopyResult = {
  deliveryNoteId: string;
  filename: string;
  status: string;
};

/**
 * Stamp the signed copy onto a delivery note AND flip its status
 * to `completed` in a single PATCH.
 */
export async function markSignedCopyReceived(
  input: SignedCopyInput
): Promise<SignedCopyResult> {
  const pb = await getAdminPocketBase();

  const dn = await pb
    .collection(DELIVERY_NOTES)
    .getOne<DeliveryNote>(input.deliveryNoteId);

  if (dn.status === "completed") {
    return {
      deliveryNoteId: dn.id,
      filename: Array.isArray(dn.signed_copy) ? dn.signed_copy[0] ?? "" : "",
      status: dn.status,
    };
  }

  // Allow signed-copy upload on ANY active status (per the
  // operator's request: "regardless of the status"). The only
  // exception is `cancelled` — that's an abandoned DN, so
  // uploading a signed copy to it would be misleading.
  if (dn.status === "cancelled") {
    throw new Error(
      `Cannot mark signed copy received on a cancelled delivery note.`,
    );
  }

  const updated = await pb.collection(DELIVERY_NOTES).update<DeliveryNote>(
    dn.id,
    {
      signed_copy: [input.file],
      status: "completed",
    }
  );

  const filename =
    (Array.isArray(updated.signed_copy) && updated.signed_copy[0]) ||
    (input.file as { name?: string }).name ||
    "signed-copy";

  return {
    deliveryNoteId: updated.id,
    filename,
    status: updated.status,
  };
}


/**
 * Mark a delivery note as `loaded` (paper is on the truck, going
 * out for delivery).
 *
 * Accepts `draft` (paper was prepared and is being loaded
 * directly, e.g. counter pickup) and `sent` (paper has been sent
 * to the customer and is now en route back via the driver). The
 * `loaded` state is a new lifecycle stop on the operator's
 * request — they want a visible "out with the driver" status
 * distinct from "sent" (paper at the customer) and
 * "po_received" (paper back with PO).
 *
 * Idempotent on `loaded`: a re-marked DN is a no-op (the
 * `updated` autodate timestamp already records the operator's
 * click). This lets the page retry safely on a flaky network
 * without double-stamping.
 *
 * Other transitions: `po_received`, `invoiced`, `completed` are
 * downstream of `loaded` and accept the signed-copy upload
 * separately. `cancelled` is rejected — the operator has to
 * un-cancel first.
 *
 * Why no `loaded_at` field: the operator opted to use PB's
 * built-in `updated` autodate as the timestamp instead of
 * adding a dedicated field. The trade-off is that any future
 * edit to the DN will shift the "loaded at" reading — acceptable
 * for an audit trail that nobody currently queries by timestamp.
 */
export async function markDeliveryNoteLoaded(
  deliveryNoteId: string,
): Promise<DeliveryNote> {
  const pb = await getAdminPocketBase();

  const dn = await pb
    .collection(DELIVERY_NOTES)
    .getOne<DeliveryNote>(deliveryNoteId);

  // Idempotent: re-marking a loaded DN is a no-op.
  if (dn.status === "loaded") {
    return dn;
  }

  if (dn.status !== "draft" && dn.status !== "sent") {
    throw new Error(
      `Cannot mark delivery note as loaded in status "${dn.status}" (must be draft or sent).`,
    );
  }

  return pb.collection(DELIVERY_NOTES).update<DeliveryNote>(dn.id, {
    status: "loaded",
  });
}