import { isApiError } from "../api/types";

export type InvoiceGuardAmountUnavailableItem = {
  itemId: string;
  invoiceIds: string[];
};

export type InvoiceGuardAmountExceededItem = {
  itemId: string;
  declaredAmount: string;
  invoiceTotal: string;
};

export type ReimbursementInvoiceGuardIssues = {
  unlinkedInvoiceCount: number;
  unlinkedInvoiceIds: string[];
  missingInvoiceItemIds: string[];
  amountUnavailableItems: InvoiceGuardAmountUnavailableItem[];
  amountExceededItems: InvoiceGuardAmountExceededItem[];
};

function readStringArray(value: unknown): string[] {
  return Array.isArray(value)
    ? value.filter((item): item is string => typeof item === "string" && item.length > 0)
    : [];
}

function readNonNegativeInteger(value: unknown): number {
  return typeof value === "number" && Number.isInteger(value) && value >= 0 ? value : 0;
}

export function parseReimbursementInvoiceGuardIssues(
  error: unknown,
): ReimbursementInvoiceGuardIssues | null {
  if (!isApiError(error) || error.details?.items !== "invoice_item_guard_failed") {
    return null;
  }

  const amountUnavailableItems = Array.isArray(error.details.amountUnavailableItems)
    ? error.details.amountUnavailableItems.flatMap((value) => {
      if (!value || typeof value !== "object") return [];
      const itemId = "itemId" in value && typeof value.itemId === "string" ? value.itemId : "";
      if (!itemId) return [];
      return [{
        itemId,
        invoiceIds: readStringArray("invoiceIds" in value ? value.invoiceIds : undefined),
      }];
    })
    : [];

  const amountExceededItems = Array.isArray(error.details.amountExceededItems)
    ? error.details.amountExceededItems.flatMap((value) => {
      if (!value || typeof value !== "object") return [];
      const itemId = "itemId" in value && typeof value.itemId === "string" ? value.itemId : "";
      const declaredAmount = "declaredAmount" in value && typeof value.declaredAmount === "string"
        ? value.declaredAmount
        : "";
      const invoiceTotal = "invoiceTotal" in value && typeof value.invoiceTotal === "string"
        ? value.invoiceTotal
        : "";
      if (!itemId || !declaredAmount || !invoiceTotal) return [];
      return [{ itemId, declaredAmount, invoiceTotal }];
    })
    : [];

  return {
    unlinkedInvoiceCount: readNonNegativeInteger(error.details.unlinkedInvoiceCount),
    unlinkedInvoiceIds: readStringArray(error.details.unlinkedInvoiceIds),
    missingInvoiceItemIds: readStringArray(error.details.missingInvoiceItemIds),
    amountUnavailableItems,
    amountExceededItems,
  };
}

export function invoiceGuardIssueCount(issues: ReimbursementInvoiceGuardIssues): number {
  return issues.unlinkedInvoiceCount
    + issues.missingInvoiceItemIds.length
    + issues.amountUnavailableItems.length
    + issues.amountExceededItems.length;
}

export function resolveInvoiceGuardIssuesAfterLink(
  issues: ReimbursementInvoiceGuardIssues | null,
  invoiceId: string,
  linkedItemId: string,
): ReimbursementInvoiceGuardIssues | null {
  if (!issues) return null;
  const locatedInvoice = issues.unlinkedInvoiceIds.includes(invoiceId);
  const unlinkedInvoiceIds = issues.unlinkedInvoiceIds.filter((id) => id !== invoiceId);
  const shouldDecreaseCount = locatedInvoice || issues.unlinkedInvoiceIds.length === 0;
  const next = {
    ...issues,
    unlinkedInvoiceCount: shouldDecreaseCount
      ? Math.max(0, issues.unlinkedInvoiceCount - 1)
      : issues.unlinkedInvoiceCount,
    unlinkedInvoiceIds,
    missingInvoiceItemIds: issues.missingInvoiceItemIds.filter((id) => id !== linkedItemId),
  };
  return invoiceGuardIssueCount(next) > 0 ? next : null;
}

export function invoiceGuardItemMessages(
  issues: ReimbursementInvoiceGuardIssues | null,
  itemId: string,
): string[] {
  if (!issues) return [];
  const messages: string[] = [];
  if (issues.missingInvoiceItemIds.includes(itemId)) {
    messages.push("尚未关联正式发票，请到“报销材料”添加发票并选择本明细。");
  }
  if (issues.amountUnavailableItems.some((item) => item.itemId === itemId)) {
    messages.push("关联发票的票面金额未识别，请重试识别或联系财务处理。");
  }
  const exceeded = issues.amountExceededItems.find((item) => item.itemId === itemId);
  if (exceeded) {
    messages.push(
      `申报金额 ¥${exceeded.declaredAmount} 高于关联发票合计 ¥${exceeded.invoiceTotal}，请补充发票或调整申报金额。`,
    );
  }
  return messages;
}

export function invoiceGuardInvoiceMessages(
  issues: ReimbursementInvoiceGuardIssues | null,
  invoiceId: string,
  linkedItemId: string | null,
): string[] {
  if (!issues) return [];
  const messages: string[] = [];
  const isUnlinked = issues.unlinkedInvoiceIds.includes(invoiceId)
    || (issues.unlinkedInvoiceIds.length === 0 && issues.unlinkedInvoiceCount > 0 && !linkedItemId);
  if (isUnlinked) {
    messages.push("这张发票还没有选择报销明细，请在下方完成关联。");
  }
  if (issues.amountUnavailableItems.some((item) => item.invoiceIds.includes(invoiceId))) {
    messages.push("这张发票未识别出票面金额，请重试识别或联系财务处理。");
  }
  return messages;
}

export function focusFirstInvoiceGuardIssue() {
  window.requestAnimationFrame(() => {
    const target = document.querySelector<HTMLElement>('[data-reimbursement-guard-issue="true"]');
    if (!target) return;
    target.focus({ preventScroll: true });
    target.scrollIntoView({ behavior: "smooth", block: "center" });
  });
}