const USED_COMPLETE_ARCHIVED_REASON = "used_complete";

const INVOICE_UNAVAILABLE_REASONS = {
  duplicateAvailable: "duplicate_available_in_company",
  duplicatePending: "duplicate_pending_in_company",
  duplicateFailed: "duplicate_failed_in_company",
  duplicateOtherOwner: "duplicate_other_owner_in_company",
  usedByCompany: "used_by_company",
};

function buildInvoiceDedupFilters({ fileSha256 = null, invoiceCode = null, invoiceNumber = null }) {
  const filters = [];
  if (fileSha256) {
    filters.push({ file_sha256: fileSha256 });
  }
  if (invoiceCode && invoiceNumber) {
    filters.push({
      invoice_code: invoiceCode,
      invoice_number: invoiceNumber,
    });
  }
  return filters;
}

function isUsedInvoice(invoice) {
  return Boolean(
    invoice?.status === "bound" ||
      invoice?.linked_reimbursement_id ||
      invoice?.travel_order_id ||
      (invoice?.status === "archived" && invoice?.archived_reason === USED_COMPLETE_ARCHIVED_REASON),
  );
}

function classifyInvoiceConflict(conflict, ownerEmployeeId) {
  if (!conflict) {
    return null;
  }

  if (isUsedInvoice(conflict)) {
    return INVOICE_UNAVAILABLE_REASONS.usedByCompany;
  }

  if (conflict.owner_employee_id && conflict.owner_employee_id !== ownerEmployeeId) {
    return INVOICE_UNAVAILABLE_REASONS.duplicateOtherOwner;
  }

  if (conflict.status === "pending_ocr") {
    return INVOICE_UNAVAILABLE_REASONS.duplicatePending;
  }

  if (conflict.status === "ocr_failed") {
    return INVOICE_UNAVAILABLE_REASONS.duplicateFailed;
  }

  return INVOICE_UNAVAILABLE_REASONS.duplicateAvailable;
}

function rankInvoiceConflict(reason) {
  switch (reason) {
    case INVOICE_UNAVAILABLE_REASONS.usedByCompany:
      return 10;
    case INVOICE_UNAVAILABLE_REASONS.duplicateOtherOwner:
      return 20;
    case INVOICE_UNAVAILABLE_REASONS.duplicateAvailable:
      return 30;
    case INVOICE_UNAVAILABLE_REASONS.duplicatePending:
      return 40;
    case INVOICE_UNAVAILABLE_REASONS.duplicateFailed:
      return 50;
    default:
      return 100;
  }
}

function pickBlockingInvoiceConflict(conflicts, ownerEmployeeId) {
  const ranked = conflicts
    .map((conflict) => ({
      conflict,
      reason: classifyInvoiceConflict(conflict, ownerEmployeeId),
    }))
    .filter((item) => item.reason)
    .sort((a, b) => rankInvoiceConflict(a.reason) - rankInvoiceConflict(b.reason));

  return ranked[0] ?? null;
}

async function findInvoiceDedupConflicts(tx, input) {
  const filters = buildInvoiceDedupFilters(input);
  if (!filters.length) {
    return [];
  }

  return tx.invoicePool.findMany({
    where: {
      ...(input.excludeInvoiceId ? { id: { not: input.excludeInvoiceId } } : {}),
      is_duplicate_override: false,
      OR: filters,
      status: { in: ["pending_ocr", "ocr_failed", "available", "bound", "archived"] },
    },
    orderBy: [{ created_at: "asc" }, { id: "asc" }],
    select: {
      id: true,
      owner_employee_id: true,
      uploaded_by_employee_id: true,
      status: true,
      archived_reason: true,
      linked_reimbursement_id: true,
      linked_item_id: true,
      travel_order_id: true,
      invoice_code: true,
      invoice_number: true,
      file_sha256: true,
      linked_reimbursement: {
        select: {
          form_number: true,
          status: true,
          owner_id: true,
          submitter_id: true,
        },
      },
    },
  });
}

async function resolveInvoiceDedupBlocker(tx, input) {
  const conflicts = await findInvoiceDedupConflicts(tx, input);
  return pickBlockingInvoiceConflict(conflicts, input.ownerEmployeeId);
}

async function resolveUploadDedupDecision(tx, { fileSha256, ownerEmployeeId }) {
  const conflicts = await findInvoiceDedupConflicts(tx, { fileSha256, ownerEmployeeId });
  const blocker = pickBlockingInvoiceConflict(conflicts, ownerEmployeeId);
  if (!blocker) {
    return { action: "create" };
  }

  const conflict = blocker.conflict;
  if (!isUsedInvoice(conflict) && conflict.owner_employee_id === ownerEmployeeId) {
    return {
      action: "reuse_existing",
      reason: blocker.reason,
      invoice: conflict,
    };
  }

  return {
    action: "blocked",
    reason: blocker.reason,
    invoice: conflict,
  };
}

function mapInvoiceUnavailableReason(reason) {
  switch (reason) {
    case INVOICE_UNAVAILABLE_REASONS.usedByCompany:
      return "该发票已用于报销，不能重复添加";
    case INVOICE_UNAVAILABLE_REASONS.duplicateOtherOwner:
      return "公司内已有相同发票，需管理员处理";
    case INVOICE_UNAVAILABLE_REASONS.duplicatePending:
      return "相同发票正在识别，请稍后刷新";
    case INVOICE_UNAVAILABLE_REASONS.duplicateFailed:
      return "相同发票已存在但识别失败，请先处理已有记录";
    case INVOICE_UNAVAILABLE_REASONS.duplicateAvailable:
      return "公司内已有相同可用发票，不能重复添加";
    default:
      return null;
  }
}

module.exports = {
  INVOICE_UNAVAILABLE_REASONS,
  buildInvoiceDedupFilters,
  classifyInvoiceConflict,
  findInvoiceDedupConflicts,
  isUsedInvoice,
  mapInvoiceUnavailableReason,
  resolveInvoiceDedupBlocker,
  resolveUploadDedupDecision,
};