/**
 * Ship Request Service
 *
 * Handles CRUD operations for shipment request carts persisted in PostgreSQL.
 * Carts are per-user, per-company. Only one active (non-submitted, non-cancelled) cart
 * is allowed at a time.
 */

import { db } from '@/lib/db';
import type {
  ShipRequestHeader,
  ShipRequestListItem,
  ShipRequestDetailItem,
  AddShipCartItemPayload,
  UpdateCartHeaderPayload,
  UpdateCartItemPayload,
} from '@/types/requests';

// =============================================================================
// Serialization helpers
// =============================================================================

function serializeDetail(
  d: {
    id: string;
    part_num: string;
    lot_num: string | null;
    plant: string;
    warehouse: string | null;
    quantity: number;
    notes: string | null;
    created_at: Date;
  }
): ShipRequestDetailItem {
  return {
    id: d.id,
    part_num: d.part_num,
    lot_num: d.lot_num,
    plant: d.plant,
    warehouse: d.warehouse,
    quantity: d.quantity,
    notes: d.notes,
    created_at: d.created_at.toISOString(),
  };
}

function serializeHeader(
  r: {
    id: string;
    auth_user_id: string;
    quest_company_id: string;
    ship_to_address: string;
    order_number: string | null;
    po_number: string | null;
    release_number: string | null;
    pickup_date: Date | null;
    instructions: string | null;
    email_recipients: string[];
    is_submitted: boolean;
    submitted_at: Date | null;
    is_cancelled: boolean;
    cancelled_at: Date | null;
    cancelled_by: string | null;
    last_cart_activity: Date;
    created_at: Date;
    updated_at: Date;
    details: {
      id: string;
      part_num: string;
      lot_num: string | null;
      plant: string;
      warehouse: string | null;
      quantity: number;
      notes: string | null;
      created_at: Date;
    }[];
  }
): ShipRequestHeader {
  return {
    id: r.id,
    auth_user_id: r.auth_user_id,
    quest_company_id: r.quest_company_id,
    ship_to_address: r.ship_to_address,
    order_number: r.order_number,
    po_number: r.po_number,
    release_number: r.release_number,
    pickup_date: r.pickup_date?.toISOString() ?? null,
    instructions: r.instructions,
    email_recipients: r.email_recipients,
    is_submitted: r.is_submitted,
    submitted_at: r.submitted_at?.toISOString() ?? null,
    is_cancelled: r.is_cancelled,
    cancelled_at: r.cancelled_at?.toISOString() ?? null,
    cancelled_by: r.cancelled_by,
    last_cart_activity: r.last_cart_activity.toISOString(),
    created_at: r.created_at.toISOString(),
    updated_at: r.updated_at.toISOString(),
    details: r.details.map(serializeDetail),
  };
}

// =============================================================================
// Cart Operations
// =============================================================================

/**
 * Get or create an active cart (unsubmitted, uncancelled) for this user+company
 */
export async function getOrCreateCart(
  userId: string,
  companyId: string
): Promise<ShipRequestHeader> {
  // Find existing active cart
  const existing = await db.ship_request.findFirst({
    where: {
      auth_user_id: userId,
      quest_company_id: companyId,
      is_submitted: false,
      is_cancelled: false,
    },
    include: { details: { orderBy: { created_at: 'asc' } } },
    orderBy: { created_at: 'desc' },
  });

  if (existing) {
    return serializeHeader(existing);
  }

  // Create new cart
  const newCart = await db.ship_request.create({
    data: {
      auth_user_id: userId,
      quest_company_id: companyId,
      ship_to_address: '',
    },
    include: { details: true },
  });

  return serializeHeader(newCart);
}

/**
 * Get a specific request by ID, scoped to a company
 */
export async function getRequestById(
  id: string,
  companyId: string
): Promise<ShipRequestHeader | null> {
  const request = await db.ship_request.findFirst({
    where: { id, quest_company_id: companyId },
    include: { details: { orderBy: { created_at: 'asc' } } },
  });

  return request ? serializeHeader(request) : null;
}

/**
 * Get all requests for a company (list view)
 */
export async function getRequests(
  companyId: string
): Promise<ShipRequestListItem[]> {
  const requests = await db.ship_request.findMany({
    where: { quest_company_id: companyId },
    include: { _count: { select: { details: true } } },
    orderBy: { created_at: 'desc' },
  });

  return requests.map((r) => ({
    id: r.id,
    ship_to_address: r.ship_to_address,
    order_number: r.order_number,
    po_number: r.po_number,
    is_submitted: r.is_submitted,
    submitted_at: r.submitted_at?.toISOString() ?? null,
    is_cancelled: r.is_cancelled,
    cancelled_at: r.cancelled_at?.toISOString() ?? null,
    created_at: r.created_at.toISOString(),
    detail_count: r._count.details,
  }));
}

/**
 * Update cart header fields (ship-to, order#, PO#, etc.)
 */
export async function updateCartHeader(
  id: string,
  companyId: string,
  data: UpdateCartHeaderPayload
): Promise<ShipRequestHeader> {
  // Verify cart belongs to company and is still active
  const cart = await db.ship_request.findFirst({
    where: { id, quest_company_id: companyId, is_submitted: false, is_cancelled: false },
  });

  if (!cart) {
    throw new Error('Cart not found or already submitted/cancelled');
  }

  const updated = await db.ship_request.update({
    where: { id },
    data: {
      ...(data.ship_to_address !== undefined && { ship_to_address: data.ship_to_address }),
      ...(data.order_number !== undefined && { order_number: data.order_number }),
      ...(data.po_number !== undefined && { po_number: data.po_number }),
      ...(data.release_number !== undefined && { release_number: data.release_number }),
      ...(data.pickup_date !== undefined && {
        pickup_date: data.pickup_date ? new Date(data.pickup_date) : null,
      }),
      ...(data.instructions !== undefined && { instructions: data.instructions }),
      ...(data.email_recipients !== undefined && { email_recipients: data.email_recipients }),
      last_cart_activity: new Date(),
    },
    include: { details: { orderBy: { created_at: 'asc' } } },
  });

  return serializeHeader(updated);
}

// =============================================================================
// Cart Item Operations
// =============================================================================

/**
 * Add an item to the cart. Checks for duplicates (same part+lot+plant+warehouse).
 */
export async function addCartItem(
  requestId: string,
  companyId: string,
  item: AddShipCartItemPayload
): Promise<ShipRequestDetailItem> {
  // Verify cart is active
  const cart = await db.ship_request.findFirst({
    where: { id: requestId, quest_company_id: companyId, is_submitted: false, is_cancelled: false },
  });

  if (!cart) {
    throw new Error('Cart not found or already submitted/cancelled');
  }

  // Check for duplicates
  const duplicate = await db.ship_request_detail.findFirst({
    where: {
      ship_request_id: requestId,
      part_num: item.part_num,
      lot_num: item.lot_num || null,
      plant: item.plant,
      warehouse: item.warehouse || null,
    },
  });

  if (duplicate) {
    throw new Error('This item already exists in the cart. Update the quantity instead.');
  }

  const detail = await db.ship_request_detail.create({
    data: {
      ship_request_id: requestId,
      part_num: item.part_num,
      lot_num: item.lot_num || null,
      plant: item.plant,
      warehouse: item.warehouse || null,
      quantity: item.quantity,
      notes: item.notes || null,
    },
  });

  // Touch cart activity
  await db.ship_request.update({
    where: { id: requestId },
    data: { last_cart_activity: new Date() },
  });

  return serializeDetail(detail);
}

/**
 * Remove an item from the cart
 */
export async function removeCartItem(
  detailId: string,
  requestId: string,
  companyId: string
): Promise<void> {
  // Verify cart is active and detail belongs to it
  const cart = await db.ship_request.findFirst({
    where: { id: requestId, quest_company_id: companyId, is_submitted: false, is_cancelled: false },
  });

  if (!cart) {
    throw new Error('Cart not found or already submitted/cancelled');
  }

  const detail = await db.ship_request_detail.findFirst({
    where: { id: detailId, ship_request_id: requestId },
  });

  if (!detail) {
    throw new Error('Item not found in cart');
  }

  await db.ship_request_detail.delete({ where: { id: detailId } });

  // Touch cart activity
  await db.ship_request.update({
    where: { id: requestId },
    data: { last_cart_activity: new Date() },
  });
}

/**
 * Update a cart item (quantity, notes)
 */
export async function updateCartItem(
  detailId: string,
  requestId: string,
  companyId: string,
  data: UpdateCartItemPayload
): Promise<ShipRequestDetailItem> {
  // Verify cart is active
  const cart = await db.ship_request.findFirst({
    where: { id: requestId, quest_company_id: companyId, is_submitted: false, is_cancelled: false },
  });

  if (!cart) {
    throw new Error('Cart not found or already submitted/cancelled');
  }

  const detail = await db.ship_request_detail.findFirst({
    where: { id: detailId, ship_request_id: requestId },
  });

  if (!detail) {
    throw new Error('Item not found in cart');
  }

  const updated = await db.ship_request_detail.update({
    where: { id: detailId },
    data: {
      ...(data.quantity !== undefined && { quantity: data.quantity }),
      ...(data.notes !== undefined && { notes: data.notes }),
    },
  });

  // Touch cart activity
  await db.ship_request.update({
    where: { id: requestId },
    data: { last_cart_activity: new Date() },
  });

  return serializeDetail(updated);
}

// =============================================================================
// Submit & Cancel
// =============================================================================

/**
 * Submit a cart (mark as submitted, lock for editing)
 */
export async function submitCart(
  id: string,
  companyId: string,
  userId: string
): Promise<ShipRequestHeader> {
  const cart = await db.ship_request.findFirst({
    where: { id, quest_company_id: companyId, is_submitted: false, is_cancelled: false },
    include: { details: true },
  });

  if (!cart) {
    throw new Error('Cart not found or already submitted/cancelled');
  }

  if (cart.details.length === 0) {
    throw new Error('Cannot submit an empty cart');
  }

  if (!cart.ship_to_address) {
    throw new Error('Ship-to address is required');
  }

  const submitted = await db.ship_request.update({
    where: { id },
    data: {
      is_submitted: true,
      submitted_at: new Date(),
    },
    include: { details: { orderBy: { created_at: 'asc' } } },
  });

  // Email notification stub (J-007 not built yet)
  console.log('[EMAIL STUB] Shipment request submitted:', {
    requestId: id,
    userId,
    companyId,
    recipients: submitted.email_recipients,
    itemCount: submitted.details.length,
  });

  return serializeHeader(submitted);
}

/**
 * Cancel a submitted request
 */
export async function cancelRequest(
  id: string,
  companyId: string,
  userId: string
): Promise<ShipRequestHeader> {
  const request = await db.ship_request.findFirst({
    where: { id, quest_company_id: companyId, is_cancelled: false },
  });

  if (!request) {
    throw new Error('Request not found');
  }

  const cancelled = await db.ship_request.update({
    where: { id },
    data: {
      is_cancelled: true,
      cancelled_at: new Date(),
      cancelled_by: userId,
    },
    include: { details: { orderBy: { created_at: 'asc' } } },
  });

  // Email notification stub
  console.log('[EMAIL STUB] Shipment request cancelled:', {
    requestId: id,
    userId,
    companyId,
    recipients: cancelled.email_recipients,
  });

  return serializeHeader(cancelled);
}

// =============================================================================
// Lightweight Cart Check (no auto-create)
// =============================================================================

/**
 * Check if an active cart exists for this user+company WITHOUT creating one.
 * Returns null if no active cart exists.
 */
export async function getActiveCart(
  userId: string,
  companyId: string
): Promise<ShipRequestHeader | null> {
  const existing = await db.ship_request.findFirst({
    where: {
      auth_user_id: userId,
      quest_company_id: companyId,
      is_submitted: false,
      is_cancelled: false,
    },
    include: { details: { orderBy: { created_at: 'asc' } } },
    orderBy: { created_at: 'desc' },
  });

  return existing ? serializeHeader(existing) : null;
}

// =============================================================================
// Batch Cart Item Operations
// =============================================================================

export type BatchAddResult = {
  added: ShipRequestDetailItem[];
  skipped: { item: AddShipCartItemPayload; reason: string }[];
  errors: { item: AddShipCartItemPayload; error: string }[];
};

/**
 * Add multiple items to the cart in one operation.
 * Skips duplicates and plant mismatches rather than throwing.
 */
export async function addBatchCartItems(
  requestId: string,
  companyId: string,
  items: AddShipCartItemPayload[]
): Promise<BatchAddResult> {
  // Verify cart is active
  const cart = await db.ship_request.findFirst({
    where: { id: requestId, quest_company_id: companyId, is_submitted: false, is_cancelled: false },
    include: { details: { orderBy: { created_at: 'asc' } } },
  });

  if (!cart) {
    throw new Error('Cart not found or already submitted/cancelled');
  }

  // Determine locked plant from existing items
  const lockedPlant = cart.details.length > 0 ? cart.details[0]!.plant : null;

  const added: ShipRequestDetailItem[] = [];
  const skipped: { item: AddShipCartItemPayload; reason: string }[] = [];
  const errors: { item: AddShipCartItemPayload; error: string }[] = [];

  for (const item of items) {
    try {
      // Plant constraint check
      if (lockedPlant && item.plant !== lockedPlant) {
        skipped.push({ item, reason: `Plant mismatch: cart is locked to ${lockedPlant}` });
        continue;
      }

      // Duplicate check
      const duplicate = await db.ship_request_detail.findFirst({
        where: {
          ship_request_id: requestId,
          part_num: item.part_num,
          lot_num: item.lot_num || null,
          plant: item.plant,
          warehouse: item.warehouse || null,
        },
      });

      if (duplicate) {
        skipped.push({ item, reason: 'Already in cart' });
        continue;
      }

      // If this is the first item, it sets the plant
      const detail = await db.ship_request_detail.create({
        data: {
          ship_request_id: requestId,
          part_num: item.part_num,
          lot_num: item.lot_num || null,
          plant: item.plant,
          warehouse: item.warehouse || null,
          quantity: item.quantity,
          notes: item.notes || null,
        },
      });

      added.push(serializeDetail(detail));
    } catch (err) {
      errors.push({ item, error: err instanceof Error ? err.message : 'Unknown error' });
    }
  }

  // Touch cart activity
  if (added.length > 0) {
    await db.ship_request.update({
      where: { id: requestId },
      data: { last_cart_activity: new Date() },
    });
  }

  return { added, skipped, errors };
}