import prisma from "../config/database";
import {
  generateSharedNumber,
  previewSharedNumber,
  releaseSharedNumber,
  isOrderNumberTaken,
} from "./numbering.service";

interface OrderItemInput {
  description?: string | null;
  item_description?: string | null;
  quantity?: number;
  unit?: string | null;
  unit_price?: number;
  is_included_in_total?: boolean;
  position?: number;
}
interface OrderSectionInput {
  title?: string | null;
  title_cz?: string | null;
  content?: string | null;
  position?: number;
}

// Status transition rules matching PHP
export const VALID_TRANSITIONS: Record<string, string[]> = {
  prijata: ["v_realizaci", "stornovana"],
  v_realizaci: ["dokoncena", "stornovana"],
  dokoncena: [],
  stornovana: [],
};

const ORDER_ALLOWED_SORT_FIELDS = [
  "id",
  "order_number",
  "status",
  "currency",
  "created_at",
];

function enrichOrder(o: any) {
  const subtotal = o.order_items
    .filter((i: any) => i.is_included_in_total !== false)
    .reduce(
      (s: number, i: any) =>
        s + (Number(i.quantity) || 0) * (Number(i.unit_price) || 0),
      0,
    );
  const vatAmount = o.apply_vat
    ? subtotal *
      ((o.vat_rate != null && o.vat_rate !== "" ? Number(o.vat_rate) : 21) /
        100)
    : 0;
  const { order_items, order_sections, ...rest } = o;
  const invoice = o.invoices?.[0] || null;
  return {
    ...rest,
    items: order_items,
    sections: order_sections,
    customer_name: o.customers?.name || null,
    quotation_number: o.quotations?.quotation_number || null,
    project_code: o.quotations?.project_code || null,
    invoice_id: invoice?.id || null,
    invoice_number: invoice?.invoice_number || null,
    subtotal: Math.round(subtotal * 100) / 100,
    vat_amount: Math.round(vatAmount * 100) / 100,
    total: Math.round((subtotal + vatAmount) * 100) / 100,
  };
}

interface ListOrdersParams {
  page: number;
  limit: number;
  skip: number;
  sort: string;
  order: "asc" | "desc";
  status?: string;
  customer_id?: number;
}

export async function listOrders(params: ListOrdersParams) {
  const { page, limit, skip, order } = params;
  const sortField = ORDER_ALLOWED_SORT_FIELDS.includes(params.sort)
    ? params.sort
    : "id";

  const where: Record<string, unknown> = {};
  if (params.status) where.status = params.status;
  if (params.customer_id) where.customer_id = params.customer_id;

  const [orders, total] = await Promise.all([
    prisma.orders.findMany({
      where,
      skip,
      take: limit,
      orderBy: { [sortField]: order },
      include: {
        customers: { select: { id: true, name: true } },
        order_items: { orderBy: { position: "asc" } },
        order_sections: { orderBy: { position: "asc" } },
        quotations: { select: { quotation_number: true, project_code: true } },
        invoices: {
          select: { id: true, invoice_number: true },
          take: 1,
          orderBy: { id: "desc" },
        },
      },
    }),
    prisma.orders.count({ where }),
  ]);

  const enriched = orders.map(enrichOrder);
  return { data: enriched, total, page, limit };
}

export async function getOrder(id: number) {
  const order = await prisma.orders.findUnique({
    where: { id },
    include: {
      customers: true,
      order_items: { orderBy: { position: "asc" } },
      order_sections: { orderBy: { position: "asc" } },
      quotations: {
        select: { id: true, quotation_number: true, project_code: true },
      },
      projects: {
        select: { id: true, project_number: true, name: true, status: true },
      },
      invoices: {
        select: { id: true, invoice_number: true, status: true },
        orderBy: { id: "desc" },
      },
    },
  });
  if (!order) return null;
  const { order_items, order_sections, ...rest } = order;
  const invoice = order.invoices?.[0] || null;
  return {
    ...rest,
    items: order_items,
    sections: order_sections,
    customer: order.customers,
    customer_name: order.customers?.name || null,
    quotation_number: order.quotations?.quotation_number || null,
    project_code: order.quotations?.project_code || null,
    project: order.projects?.[0] || null,
    invoice: invoice,
    invoice_id: invoice?.id || null,
    invoice_number: invoice?.invoice_number || null,
    valid_transitions: VALID_TRANSITIONS[(order.status as string) || ""] || [],
  };
}

export async function getOrderAttachment(id: number) {
  const order = await prisma.orders.findUnique({
    where: { id },
    select: { attachment_data: true, attachment_name: true },
  });
  if (!order?.attachment_data) return null;
  return {
    data: Buffer.from(order.attachment_data),
    filename: order.attachment_name || `order-${id}.pdf`,
  };
}

interface CreateOrderFromQuotationData {
  quotationId: number;
  customerOrderNumber?: string;
  attachmentBuffer?: Buffer | null;
  attachmentName?: string | null;
}

export async function createOrderFromQuotation(
  data: CreateOrderFromQuotationData,
) {
  const { quotationId, customerOrderNumber, attachmentBuffer, attachmentName } =
    data;

  const quotation = await prisma.quotations.findUnique({
    where: { id: quotationId },
    include: {
      quotation_items: { orderBy: { position: "asc" } },
      scope_sections: { orderBy: { position: "asc" } },
    },
  });

  if (!quotation) return { error: "Nabídka nenalezena", status: 404 } as const;
  if (quotation.order_id)
    return {
      error: "Z této nabídky již byla vytvořena objednávka",
      status: 400,
    } as const;

  const result = await prisma.$transaction(async (tx) => {
    const orderNumber = await generateSharedNumber(tx);
    const projectNumber = orderNumber;

    const order = await tx.orders.create({
      data: {
        order_number: orderNumber,
        customer_order_number: customerOrderNumber || null,
        quotation_id: quotationId,
        customer_id: quotation.customer_id,
        status: "prijata",
        currency: quotation.currency || "CZK",
        language: quotation.language || "cs",
        vat_rate: quotation.vat_rate ?? 21.0,
        apply_vat: quotation.apply_vat ?? true,
        exchange_rate: quotation.exchange_rate ?? 1.0,
        scope_title: quotation.scope_title,
        scope_description: quotation.scope_description,
        attachment_data: attachmentBuffer
          ? new Uint8Array(attachmentBuffer)
          : null,
        attachment_name: attachmentName || null,
      },
    });

    if (quotation.quotation_items.length > 0) {
      await tx.order_items.createMany({
        data: quotation.quotation_items.map((item) => ({
          order_id: order.id,
          description: item.description,
          item_description: item.item_description,
          quantity: item.quantity,
          unit: item.unit,
          unit_price: item.unit_price,
          is_included_in_total: item.is_included_in_total,
          position: item.position,
        })),
      });
    }

    if (quotation.scope_sections.length > 0) {
      await tx.order_sections.createMany({
        data: quotation.scope_sections.map((s) => ({
          order_id: order.id,
          title: s.title,
          title_cz: s.title_cz,
          content: s.content,
          position: s.position,
        })),
      });
    }

    await tx.quotations.update({
      where: { id: quotationId },
      data: { order_id: order.id, status: "ordered", modified_at: new Date() },
    });

    const project = await tx.projects.create({
      data: {
        project_number: projectNumber,
        name:
          quotation.project_code || quotation.quotation_number || orderNumber,
        customer_id: quotation.customer_id,
        quotation_id: quotationId,
        order_id: order.id,
        status: "aktivni",
      },
    });

    return { order, project, orderNumber };
  });

  return {
    data: {
      order_id: result.order.id,
      id: result.order.id,
      order_number: result.orderNumber,
      quotationId,
    },
  };
}

interface CreateOrderData {
  order_number?: string | null;
  customer_order_number?: string | null;
  quotation_id?: number | null;
  customer_id?: number | null;
  status: string;
  currency: string;
  language: string;
  vat_rate: number;
  apply_vat?: boolean;
  exchange_rate?: number;
  scope_title?: string | null;
  scope_description?: string | null;
  notes?: string | null;
  items?: OrderItemInput[];
  sections?: OrderSectionInput[];
}

export async function createOrder(body: CreateOrderData) {
  try {
    return await prisma.$transaction(async (tx) => {
      const orderNumber =
        body.order_number !== undefined && body.order_number !== null
          ? String(body.order_number)
          : await generateSharedNumber(tx);

      if (body.order_number !== undefined && body.order_number !== null) {
        const taken = await isOrderNumberTaken(String(body.order_number));
        if (taken) {
          throw Object.assign(new Error("Číslo objednávky je již použito"), {
            status: 400,
          });
        }
      }

      const order = await tx.orders.create({
        data: {
          order_number: orderNumber,
          customer_order_number: body.customer_order_number ?? null,
          quotation_id: body.quotation_id ?? null,
          customer_id: body.customer_id ?? null,
          status: body.status,
          currency: body.currency,
          language: body.language,
          vat_rate: body.vat_rate,
          apply_vat: body.apply_vat !== false,
          exchange_rate: body.exchange_rate,
          scope_title: body.scope_title ?? null,
          scope_description: body.scope_description ?? null,
          notes: body.notes ?? null,
        },
      });

      if (Array.isArray(body.items)) {
        await tx.order_items.createMany({
          data: body.items.map((item, i) => ({
            order_id: order.id,
            description: item.description ?? null,
            item_description: item.item_description ?? null,
            quantity: item.quantity ?? 1,
            unit: item.unit ?? null,
            unit_price: item.unit_price ?? 0,
            is_included_in_total: item.is_included_in_total !== false,
            position: item.position ?? i,
          })),
        });
      }

      if (Array.isArray(body.sections)) {
        await tx.order_sections.createMany({
          data: body.sections.map((s, i) => ({
            order_id: order.id,
            title: s.title ?? null,
            title_cz: s.title_cz ?? null,
            content: s.content ?? null,
            position: s.position ?? i,
          })),
        });
      }

      return { id: order.id, order_number: order.order_number };
    });
  } catch (err) {
    if (err instanceof Error && "status" in err) {
      return {
        error: err.message,
        status: (err as Error & { status: number }).status,
      };
    }
    throw err;
  }
}

interface UpdateOrderData {
  [key: string]: unknown;
  customer_id?: number | string | null;
  items?: OrderItemInput[];
  sections?: OrderSectionInput[];
}

export async function updateOrder(id: number, body: UpdateOrderData) {
  const existing = await prisma.orders.findUnique({ where: { id } });
  if (!existing)
    return { error: "Objednávka nenalezena", status: 404 } as const;

  const currentStatus = existing.status as string;

  if (
    body.order_number !== undefined &&
    String(body.order_number) !== existing.order_number
  ) {
    return {
      error: "Číslo objednávky nelze změnit",
      status: 400,
    } as const;
  }

  if (body.status !== undefined && String(body.status) !== currentStatus) {
    const newStatus = String(body.status);
    const allowed = VALID_TRANSITIONS[currentStatus] || [];
    if (!allowed.includes(newStatus)) {
      return {
        error: `Neplatný přechod stavu z "${currentStatus}" na "${newStatus}"`,
        status: 400,
      } as const;
    }
  }

  const data: Record<string, unknown> = { modified_at: new Date() };
  const strFields = [
    "customer_order_number",
    "status",
    "currency",
    "language",
    "scope_title",
    "scope_description",
    "notes",
  ];
  for (const f of strFields) {
    if (body[f] !== undefined) data[f] = body[f] ? String(body[f]) : null;
  }
  if (body.customer_id !== undefined)
    data.customer_id = body.customer_id ? Number(body.customer_id) : null;
  if (body.vat_rate !== undefined) data.vat_rate = Number(body.vat_rate);
  if (body.apply_vat !== undefined)
    data.apply_vat =
      body.apply_vat === true || body.apply_vat === 1 || body.apply_vat === "1";

  if (Array.isArray(body.items) || Array.isArray(body.sections)) {
    if (currentStatus !== "prijata" && currentStatus !== "v_realizaci") {
      return {
        error: "Nelze upravit položky dokončené/stornované objednávky",
        status: 400,
      } as const;
    }
    if (
      body.status !== undefined &&
      (String(body.status) === "dokoncena" ||
        String(body.status) === "stornovana")
    ) {
      return {
        error: "Nelze upravit položky při změně stavu na dokončeno/storno",
        status: 400,
      } as const;
    }
    await prisma.$transaction(async (tx) => {
      await tx.orders.update({ where: { id }, data });

      // Sync project status when order status changes (matching PHP)
      if (body.status !== undefined && String(body.status) !== currentStatus) {
        const statusMap: Record<string, string> = {
          v_realizaci: "aktivni",
          dokoncena: "dokonceny",
          stornovana: "zruseny",
        };
        const projectStatus = statusMap[String(body.status)];
        if (projectStatus) {
          await tx.projects.updateMany({
            where: { order_id: id },
            data: { status: projectStatus },
          });
        }
      }

      if (Array.isArray(body.items)) {
        await tx.order_items.deleteMany({ where: { order_id: id } });
        await tx.order_items.createMany({
          data: (body.items as OrderItemInput[]).map((item, i) => ({
            order_id: id,
            description: item.description ?? null,
            item_description: item.item_description ?? null,
            quantity: item.quantity ?? 1,
            unit: item.unit ?? null,
            unit_price: item.unit_price ?? 0,
            is_included_in_total: item.is_included_in_total !== false,
            position: item.position ?? i,
          })),
        });
      }
      if (Array.isArray(body.sections)) {
        await tx.order_sections.deleteMany({ where: { order_id: id } });
        await tx.order_sections.createMany({
          data: (body.sections as OrderSectionInput[]).map((s, i) => ({
            order_id: id,
            title: s.title ?? null,
            title_cz: s.title_cz ?? null,
            content: s.content ?? null,
            position: s.position ?? i,
          })),
        });
      }
    });
  } else {
    await prisma.orders.update({ where: { id }, data });

    // Sync project status when order status changes (matching PHP)
    if (body.status !== undefined && String(body.status) !== currentStatus) {
      const statusMap: Record<string, string> = {
        v_realizaci: "aktivni",
        dokoncena: "dokonceny",
        stornovana: "zruseny",
      };
      const projectStatus = statusMap[String(body.status)];
      if (projectStatus) {
        await prisma.projects.updateMany({
          where: { order_id: id },
          data: { status: projectStatus },
        });
      }
    }
  }

  return { data: { id, order_number: existing.order_number } };
}

export async function deleteOrder(id: number) {
  const existing = await prisma.orders.findUnique({ where: { id } });
  if (!existing)
    return { error: "Objednávka nenalezena", status: 404 } as const;

  // Fetch linked projects before the transaction for number release later
  const linkedProjects = await prisma.projects.findMany({
    where: { order_id: id },
    select: { id: true, created_at: true },
  });

  await prisma.$transaction(async (tx) => {
    // Clear quotation back-reference (matching PHP)
    await tx.quotations.updateMany({
      where: { order_id: id },
      data: { order_id: null },
    });

    // Delete linked project and its notes (matching PHP)
    if (linkedProjects.length > 0) {
      const projectIds = linkedProjects.map((p) => p.id);
      await tx.project_notes.deleteMany({
        where: { project_id: { in: projectIds } },
      });
      await tx.projects.deleteMany({ where: { order_id: id } });
    }

    // Explicitly clean up child rows
    await tx.order_items.deleteMany({ where: { order_id: id } });
    await tx.order_sections.deleteMany({ where: { order_id: id } });

    await tx.orders.delete({ where: { id } });
  });

  const year = existing.created_at
    ? new Date(existing.created_at).getFullYear()
    : new Date().getFullYear();
  await releaseSharedNumber(year, existing.order_number ?? undefined);

  return { data: { id, order_number: existing.order_number } };
}

export async function getNextOrderNumber() {
  return previewSharedNumber();
}