/**
 * Driver stops — unified list + status update for the driver app.
 *
 * The driver app needs to see two kinds of stops:
 *
 *   - **delivery** (a `order_items` row in `collection_pool` /
 *     `assigned` state) — driver takes goods to a customer.
 *   - **pickup**    (a `stock_purchase_items` row in
 *     `collection_pool` / `assigned_to_driver` state) — driver
 *     picks up goods from a supplier and brings them to the
 *     office.
 *
 * Both kinds render in the same list (one stop per row) with
 * a `kind` discriminator so the driver app can show different
 * copy + icons. The status update accepts `action: "collected"`
 * (happy path) or `action: "problem"` (driver flags an issue
 * at the supplier / customer) + the `qty_collected` the driver
 * actually got (mandatory for pickups, since suppliers short-
 * ship; default-to-line-qty for deliveries).
 *
 * Mirrors the union query on `/collection-pool/page.tsx:load()`
 * + the stock-out flow on `/collection-confirm/page.tsx:load()`.
 * The union is mirrored at the service level rather than
 * querying the legacy `collection_pool` collection (which was
 * deprecated in the v4 stock-order driver flow).
 */

import { getAdminPocketBase } from "./pocketbase-admin";
import type { OrderItem, StockPurchaseItem, Supplier } from "@/lib/types";

/* ============================================================================
 * Shared types
 * ========================================================================== */

export type DriverStopKind = "delivery" | "pickup";

/** The lifecycle states a stop can be in from the driver's POV. */
export type DriverStopStatus =
  // Deliveries:
  | "collection_pool"
  | "assigned"
  | "collected"
  | "delivered"
  // Pickups:
  | "assigned_to_driver"
  | "booked";

/** What the driver reports when they tap "Mark collected" / "Flag problem". */
export type DriverStopAction = "collected" | "problem";

/** Structured problem categories — mirrors `order_items.problem_type` values. */
export const PROBLEM_TYPES = [
  "short_supply",
  "wrong_item",
  "damaged",
  "no_show",
  "other",
] as const;

export type ProblemType = (typeof PROBLEM_TYPES)[number];

/* ============================================================================
 * Normalised stop shape (returned by `listDriverStops` and update endpoints)
 * ========================================================================== */

export interface DriverStop {
  /** PB id of the underlying row (order_item or stock_purchase_item). */
  id: string;
  /** Discriminator for the driver app's UI. */
  kind: DriverStopKind;
  /** Human-readable description of what's being delivered / picked up. */
  description: string;
  /** What was ordered / what the supplier was supposed to ship. */
  quantity_ordered: number;
  /** What the driver actually has / will deliver. For deliveries
   *  this equals `quantity_ordered` on first collection (operator
   *  adjusts at /collection-confirm). For pickups it's what the
   *  driver types at the supplier door. */
  quantity_collected: number;
  /** Lifecycle state from the underlying collection, normalised. */
  status: DriverStopStatus;
  /** Driver bound to this stop, or `null` for unassigned. */
  drv_id: string | null;
  /** ISO timestamp of the most recent assignment (date-only on stock side). */
  assigned_at: string | null;
  /** ISO timestamp of when the underlying PB row was created. Useful
   *  for "outstanding N days" reporting from the driver app / n8n. */
  created_at: string | null;
  /** ISO timestamp of when the parent order / purchase-order was
   *  created in WFDASH. This is the canonical "this thing came into
   *  the system on day X" timestamp — distinct from `assigned_at`
   *  (when a driver was put on it) and `created_at` (when the line
   *  item was added, which can differ if the line was split). Use
   *  this for "outstanding N days" reporting. */
  outstanding_since: string | null;
  /** Parent PO number, formatted for display. */
  po_number: string;
  /** Parent order id (delivery only — `null` for pickups). */
  order_id: string | null;
  /** Customer name (delivery only) / supplier name (both). */
  customer_name: string | null;
  company_name: string | null;
  /** Supplier for both kinds. */
  supplier: {
    id: string;
    name: string;
    /** Geocoded coords for the supplier's physical address — pickup
     *  stops anchor here. For deliveries the driver still passes
     *  by the supplier to drop off (in our model the supplier
     *  is the PO's destination) but the actual delivery address
     *  is `customer.coords` below. */
    coords: [number, number] | null;
  };
  /** Customer + delivery address (delivery only). */
  customer: {
    name: string;
    company: string | null;
    /** Geocoded coords for the customer's delivery address. */
    coords: [number, number] | null;
  } | null;
  /** Problem flag — set by the driver via `action: "problem"`. */
  problem: {
    flag: boolean;
    type: string | null;
    notes: string | null;
  };
}

/* ============================================================================
 * List
 * ========================================================================== */

export interface ListDriverStopsOpts {
  /** Filter by driver id. `null` = unassigned stops; `undefined` = all. */
  drv_id?: string | null;
  /** Filter by kind. */
  kind?: DriverStopKind;
  page?: number;
  perPage?: number;
}

export interface ListDriverStopsResult {
  items: DriverStop[];
  totalItems: number;
  page: number;
  perPage: number;
  totalPages: number;
}

function parseCoords(raw: unknown): [number, number] | null {
  if (Array.isArray(raw)) {
    return finiteCoordinatePair(raw[0], raw[1]);
  }
  if (raw && typeof raw === "object") {
    const point = raw as Record<string, unknown>;
    return finiteCoordinatePair(
      point.lat ?? point.latitude,
      point.lng ?? point.lon ?? point.longitude,
    );
  }
  if (typeof raw !== "string" || !raw.trim()) return null;

  const parts = raw.split(",").map((value) => Number(value.trim()));
  return finiteCoordinatePair(parts[0], parts[1]);
}

function finiteCoordinatePair(firstValue: unknown, secondValue: unknown): [number, number] | null {
  const first = Number(firstValue);
  const second = Number(secondValue);
  if (!Number.isFinite(first) || !Number.isFinite(second)) return null;
  return [first, second];
}

/**
 * Returns the driver-visible stops. Default scope: stops that
 * are still in flight (deliveries in `collection_pool` or
 * `assigned`; pickups in `collection_pool` or
 * `assigned_to_driver`). The driver app can additionally pass
 * `drv_id` to scope to a specific driver, or `null` for
 * unassigned.
 */
export async function listDriverStops(
  opts: ListDriverStopsOpts = {},
): Promise<ListDriverStopsResult> {
  const pb = await getAdminPocketBase();
  const page = Math.max(1, opts.page ?? 1);
  const perPage = Math.min(200, Math.max(1, opts.perPage ?? 50));
  const wantDelivery = !opts.kind || opts.kind === "delivery";
  const wantPickup = !opts.kind || opts.kind === "pickup";

  // We run the two queries in parallel — PB can't union across
  // collections, so we normalise the two result shapes client-side.
  const [deliveryRes, pickupRes] = await Promise.all([
    wantDelivery
      ? pb.collection("order_items").getList<DeliveryRow>(page, perPage, {
          filter: deliveryFilter(opts.drv_id),
          sort: "assigned_at,created",
          expand: "purchase_order.supplier,order.customer,order.company",
        })
      : Promise.resolve(emptyPage<DeliveryRow>()),
    wantPickup
      ? pb.collection("stock_purchase_items").getList<PickupRow>(page, perPage, {
          filter: pickupFilter(opts.drv_id),
          sort: "assigned_at,created",
          expand: "purchase.supplier,stock_item",
        })
      : Promise.resolve(emptyPage<PickupRow>()),
  ]);

  const items: DriverStop[] = [];
  for (const r of deliveryRes.items) items.push(normaliseDelivery(r));
  for (const r of pickupRes.items) items.push(normalisePickup(r));

  // Sort combined list by assigned_at (oldest first) so the
  // driver app's "next stop" hint works without extra client
  // logic.
  items.sort((a, b) => {
    const at = a.assigned_at ?? "";
    const bt = b.assigned_at ?? "";
    return at.localeCompare(bt);
  });

  return {
    items,
    totalItems: deliveryRes.totalItems + pickupRes.totalItems,
    page,
    perPage,
    totalPages: Math.max(
      deliveryRes.totalPages,
      pickupRes.totalPages,
    ),
  };
}

function deliveryFilter(drvId?: string | null): string {
  // Default: stop states the driver app surfaces. Excludes
  // terminal / pre-pool states (delivered, cancelled, ready_invoice,
  // invoiced, stock_booked).
  const parts = [
    `(item_status = "collection_pool" || item_status = "assigned")`,
    `ready_for_collection = true`,
  ];
  if (drvId === null) {
    parts.push(`(drv_id = "" || drv_id = null)`);
  } else if (drvId !== undefined) {
    parts.push(`drv_id = "${escapeForFilter(drvId)}"`);
  }
  return parts.join(" && ");
}

function pickupFilter(drvId?: string | null): string {
  const parts = [
    `(status = "collection_pool" || status = "assigned_to_driver")`,
  ];
  if (drvId === null) {
    parts.push(`(drv_id = "" || drv_id = null)`);
  } else if (drvId !== undefined) {
    parts.push(`drv_id = "${escapeForFilter(drvId)}"`);
  }
  return parts.join(" && ");
}

function escapeForFilter(s: string): string {
  return s.replace(/\\/g, "\\\\").replace(/"/g, '\\"');
}

function emptyPage<T>(): { items: T[]; totalItems: number; page: number; perPage: number; totalPages: number } {
  return { items: [], totalItems: 0, page: 1, perPage: 50, totalPages: 0 };
}

/* ============================================================================
 * Normalisers
 * ========================================================================== */

type DeliveryRow = OrderItem & {
  expand?: {
    purchase_order?: {
      id: string;
      po_number?: string;
      expand?: { supplier?: Supplier };
    };
    order?: {
      id: string;
      order_number?: string;
      expand?: {
        customer?: { id: string; customer?: string; coordinates?: string };
        company?: { id: string; company?: string; coordinates?: string };
      };
    };
  };
};

type PickupRow = StockPurchaseItem & {
  expand?: {
    purchase?: {
      id: string;
      purchase_number?: string;
      expand?: { supplier?: Supplier };
    };
    stock_item?: { id: string; sku?: string; name?: string };
  };
};

function normaliseDelivery(r: DeliveryRow): DriverStop {
  const supplier = r.expand?.purchase_order?.expand?.supplier;
  const order = r.expand?.order;
  const customer = order?.expand?.customer;
  const company = order?.expand?.company;
  return {
    id: r.id,
    kind: "delivery",
    description: r.description || "(no description)",
    quantity_ordered: Number(r.order_qty ?? r.quantity ?? 0),
    quantity_collected: Number(r.qty_collected ?? 0),
    status: (r.item_status ?? "collection_pool") as DriverStopStatus,
    drv_id: r.drv_id || null,
    assigned_at: r.assigned_at || null,
    created_at: r.created || null,
    outstanding_since: order?.created || null,
    po_number: r.expand?.purchase_order?.po_number || "",
    order_id: order?.id || null,
    customer_name: customer?.customer || null,
    company_name: company?.company || null,
    supplier: {
      id: supplier?.id || "",
      name: supplier?.suppliername || "Unknown supplier",
      coords: parseCoords(supplier?.coordinates),
    },
    customer: customer
      ? {
          name: customer.customer || "",
          company: company?.company || null,
          coords: parseCoords(customer.coordinates) ?? parseCoords(company?.coordinates),
        }
      : null,
    problem: {
      flag: Boolean(r.problem_flag),
      type: r.problem_type || null,
      notes: r.problem_notes || null,
    },
  };
}

function normalisePickup(r: PickupRow): DriverStop {
  const supplier = r.expand?.purchase?.expand?.supplier;
  return {
    id: r.id,
    kind: "pickup",
    description: r.description || "(no description)",
    quantity_ordered: Number(r.quantity ?? 0),
    quantity_collected: Number(r.quantity_received ?? 0),
    status: (r.status ?? "collection_pool") as DriverStopStatus,
    drv_id: r.drv_id || null,
    assigned_at: r.assigned_at || null,
    created_at: r.created || null,
    outstanding_since: r.expand?.purchase?.created || null,
    po_number: r.expand?.purchase?.purchase_number || "",
    order_id: null,
    customer_name: null,
    company_name: null,
    supplier: {
      id: supplier?.id || "",
      name: supplier?.suppliername || "Unknown supplier",
      coords: parseCoords(supplier?.coordinates),
    },
    customer: null,
    problem: {
      flag: Boolean(r.problem_flag),
      type: r.problem_type || null,
      notes: r.problem_notes || null,
    },
  };
}

/* ============================================================================
 * Update
 * ========================================================================== */

export interface UpdateDriverStopInput {
  id: string;
  kind: DriverStopKind;
  action: DriverStopAction;
  /** Required for `kind=pickup, action=collected`. Optional for
   *  `kind=delivery` (defaults to the line's `quantity_ordered`). */
  qty_collected?: number;
  /** Required for `action=problem`. */
  problem_type?: ProblemType;
  /** Optional free-text. Clamped to 1000 chars server-side. */
  problem_notes?: string;
  /** Optional free-text on the underlying record. */
  notes?: string;
}

export type UpdateDriverStopOk = {
  ok: true;
  stop: DriverStop;
};

export type UpdateDriverStopRejected = {
  ok: false;
  reason:
    | "invalid_kind"
    | "invalid_action"
    | "invalid_qty"
    | "problem_requires_type"
    | "stock_line_missing"
    | "stock_line_wrong_status"
    | "delivery_line_missing"
    | "update_failed";
  message: string;
};

export type UpdateDriverStopResult =
  | UpdateDriverStopOk
  | UpdateDriverStopRejected;

const NOTES_MAX = 1000;

/**
 * Apply the driver's status update to the underlying row.
 * Branches on `kind` to write to `order_items` (delivery) or
 * `stock_purchase_items` (pickup).
 *
 * Audit BEFORE state mutation: we read the row first, validate
 * the action is legal for its current status, then write. This
 * keeps the error path simple and the operator's surface
 * self-explanatory.
 */
export async function updateDriverStopStatus(
  input: UpdateDriverStopInput,
): Promise<UpdateDriverStopResult> {
  if (input.kind !== "delivery" && input.kind !== "pickup") {
    return {
      ok: false,
      reason: "invalid_kind",
      message: 'kind must be "delivery" or "pickup"',
    };
  }
  if (input.action !== "collected" && input.action !== "problem") {
    return {
      ok: false,
      reason: "invalid_action",
      message: 'action must be "collected" or "problem"',
    };
  }
  if (input.action === "problem" && !input.problem_type) {
    return {
      ok: false,
      reason: "problem_requires_type",
      message: "problem_type is required when action is problem",
    };
  }

  const pb = await getAdminPocketBase();

  if (input.kind === "pickup") {
    return updatePickup(pb, input);
  }
  return updateDelivery(pb, input);
}

async function updatePickup(
  pb: Awaited<ReturnType<typeof getAdminPocketBase>>,
  input: UpdateDriverStopInput,
): Promise<UpdateDriverStopResult> {
  // Fetch the line so we can default the qty + validate status.
  let line: Record<string, unknown>;
  try {
    line = await pb.collection("stock_purchase_items").getOne(input.id, {
      expand: "purchase.supplier,stock_item",
    });
  } catch {
    return {
      ok: false,
      reason: "stock_line_missing",
      message: "Stock line not found.",
    };
  }
  const lineTyped = line as unknown as PickupRow;
  const currentStatus = String(lineTyped.status ?? "");
  if (
    currentStatus !== "assigned_to_driver" &&
    currentStatus !== "collection_pool" &&
    currentStatus !== "collected"
  ) {
    return {
      ok: false,
      reason: "stock_line_wrong_status",
      message: `Cannot update stock line in status "${currentStatus}".`,
    };
  }

  // Resolve the qty. Pickups REQUIRE an explicit qty — supplier
  // short-shipping is the whole point of this code path. If the
  // driver doesn't provide one, we reject rather than default.
  let qtyCollected: number;
  if (input.action === "collected") {
    if (input.qty_collected === undefined) {
      return {
        ok: false,
        reason: "invalid_qty",
        message: "qty_collected is required for pickup stops (supplier may short-ship).",
      };
    }
    if (
      typeof input.qty_collected !== "number" ||
      !Number.isFinite(input.qty_collected) ||
      input.qty_collected < 0
    ) {
      return {
        ok: false,
        reason: "invalid_qty",
        message: "qty_collected must be a non-negative number.",
      };
    }
    qtyCollected = Math.floor(input.qty_collected);
  } else {
    // action=problem — qty is optional; if not given, leave
    // quantity_received as-is (or 0).
    qtyCollected = input.qty_collected !== undefined
      ? Math.floor(input.qty_collected)
      : Number(lineTyped.quantity_received ?? 0);
  }

  // For "collected" we cap at the line's ordered qty — going
  // over means the supplier shipped extra, which is the
  // "surplus" flow (v1) on the office side, not a driver input.
  if (input.action === "collected") {
    const ordered = Number(lineTyped.quantity ?? 0);
    if (qtyCollected > ordered) {
      return {
        ok: false,
        reason: "invalid_qty",
        message: `Cannot collect more than the ordered qty (${ordered}). Excess becomes surplus — the office books that separately.`,
      };
    }
  }

  // Compose the patch.
  const patch: Record<string, unknown> = {
    quantity_received: qtyCollected,
  };
  if (input.action === "collected") {
    // Happy path: status flips to "collected" so the office
    // sees it on /collection-confirm and can book to stock.
    patch.status = "collected";
    // Clear any previous problem flag — the goods are in.
    patch.problem_flag = false;
    patch.problem_type = null;
    patch.problem_notes = null;
  } else {
    // Problem: keep the goods (if any qty was collected) but
    // flag the issue for office follow-up. We don't change the
    // status — the office decides what to do.
    patch.problem_flag = true;
    patch.problem_type = input.problem_type;
    patch.problem_notes = (input.problem_notes ?? "").slice(0, NOTES_MAX);
  }
  if (input.notes !== undefined) {
    // Mirror customer-side behaviour: don't overwrite existing
    // notes; just append a one-liner so the office can see the
    // driver's last update.
    const existing = String(lineTyped.notes ?? "");
    const stamp = `[${new Date().toISOString()}] driver: ${input.notes}`;
    patch.notes = existing ? `${existing}\n${stamp}` : stamp;
  }

  try {
    await pb.collection("stock_purchase_items").update(input.id, patch);
  } catch (err) {
    return {
      ok: false,
      reason: "update_failed",
      message: err instanceof Error ? err.message : "Update failed",
    };
  }

  // Re-read so the response includes the expanded relations
  // (supplier / stock_item) the driver app needs to render.
  const fresh = (await pb.collection("stock_purchase_items").getOne(input.id, {
    expand: "purchase.supplier,stock_item",
  })) as unknown as PickupRow;
  return { ok: true, stop: normalisePickup(fresh) };
}

async function updateDelivery(
  pb: Awaited<ReturnType<typeof getAdminPocketBase>>,
  input: UpdateDriverStopInput,
): Promise<UpdateDriverStopResult> {
  let line: Record<string, unknown>;
  try {
    line = await pb.collection("order_items").getOne(input.id, {
      expand: "purchase_order.supplier,order.customer,order.company",
    });
  } catch {
    return {
      ok: false,
      reason: "delivery_line_missing",
      message: "Order item not found.",
    };
  }
  const lineTyped = line as unknown as DeliveryRow;
  const currentStatus = String(lineTyped.item_status ?? "");
  if (
    currentStatus !== "assigned" &&
    currentStatus !== "collection_pool"
  ) {
    return {
      ok: false,
      reason: "delivery_line_missing",
      message: `Cannot update delivery in status "${currentStatus}".`,
    };
  }

  // Compose the patch. For deliveries, `qty_collected` is
  // optional — if the driver doesn't provide it, default to
  // the line's `order_qty` (existing behaviour — operator can
  // still adjust at /collection-confirm).
  //
  // `order_qty` is deliberate here and must NOT be changed to
  // `quantity`: the driver is collecting from the SUPPLIER, so the
  // expected full pickup is what we put on that supplier's PO. On a
  // MOQ line that is the larger number, and collecting all of it is
  // correct — the overflow becomes stock further down the flow.
  // Customer-facing quantities live in `src/lib/order-item-qty.ts`.
  const qtyCollected =
    input.qty_collected !== undefined
      ? Math.floor(input.qty_collected)
      : Number(lineTyped.order_qty ?? lineTyped.quantity ?? 0);

  const patch: Record<string, unknown> = {
    qty_collected: qtyCollected,
  };
  if (input.action === "collected") {
    patch.item_status = "collected";
    patch.problem_flag = false;
    patch.problem_type = null;
    patch.problem_notes = null;
  } else {
    patch.problem_flag = true;
    patch.problem_type = input.problem_type;
    patch.problem_notes = (input.problem_notes ?? "").slice(0, NOTES_MAX);
  }
  if (input.notes !== undefined) {
    const existing = String(lineTyped.notes ?? "");
    const stamp = `[${new Date().toISOString()}] driver: ${input.notes}`;
    patch.notes = existing ? `${existing}\n${stamp}` : stamp;
  }

  try {
    await pb.collection("order_items").update(input.id, patch);
  } catch (err) {
    return {
      ok: false,
      reason: "update_failed",
      message: err instanceof Error ? err.message : "Update failed",
    };
  }

  const fresh = (await pb.collection("order_items").getOne(input.id, {
    expand: "purchase_order.supplier,order.customer,order.company",
  })) as unknown as DeliveryRow;
  return { ok: true, stop: normaliseDelivery(fresh) };
}