import type { PlaitElement, Point } from "@plait/core";
import { MindLayoutType } from "@plait/layouts";
import {
  createMindElement,
  type MindElement,
  type PlaitMind,
} from "@plait/mind";

import { importXmind, type ImportedMindMap } from "./xmind-import";
export { MindMapImportError } from "./xmind-import";

export const FLOW_BOARD_MIND_MAP_IMPORT_ACCEPT =
  ".md,.markdown,.mdown,.mkd,.opml,.mm,.xmind,text/markdown,text/plain,text/xml,application/xml";

type MindMapImportFormat = "markdown" | "opml" | "freemind" | "xmind";

type OutlineNode = {
  text: string;
  children: OutlineNode[];
};

function normalizeText(value: string | null | undefined) {
  return String(value || "")
    .replace(/\s+/g, " ")
    .trim();
}

export function getMindMapImportTitle(fileName: string) {
  const title = fileName
    .replace(/\.(md|markdown|mdown|mkd|opml|mm|xmind)$/i, "")
    .trim();
  return title || "导入思维导图";
}

function detectMindMapImportFormat(file: File): MindMapImportFormat | null {
  const fileName = file.name.toLowerCase();
  if (
    fileName.endsWith(".md") ||
    fileName.endsWith(".markdown") ||
    fileName.endsWith(".mdown") ||
    fileName.endsWith(".mkd")
  ) {
    return "markdown";
  }
  if (fileName.endsWith(".opml")) {
    return "opml";
  }
  if (fileName.endsWith(".mm")) {
    return "freemind";
  }
  if (fileName.endsWith(".xmind")) {
    return "xmind";
  }
  if (file.type === "text/markdown" || file.type === "text/plain") {
    return "markdown";
  }
  return null;
}

export function isSupportedMindMapImportFile(file: File) {
  return Boolean(detectMindMapImportFormat(file));
}

function hasMarkdownHeading(markdownText: string) {
  return /^\s{0,3}#{1,6}\s+\S+/m.test(markdownText);
}

function parseXmlDocument(xmlText: string, formatLabel: string) {
  if (typeof DOMParser === "undefined") {
    throw new Error(`${formatLabel} import requires DOMParser`);
  }

  const document = new DOMParser().parseFromString(xmlText, "application/xml");
  if (document.getElementsByTagName("parsererror").length > 0) {
    throw new Error(`${formatLabel} XML parse failed`);
  }
  return document;
}

function getDirectChildrenByTag(element: Element, tagName: string) {
  const normalizedTagName = tagName.toLowerCase();
  return Array.from(element.children).filter(
    (child) => child.tagName.toLowerCase() === normalizedTagName
  );
}

function createMindFromOutline(root: OutlineNode): PlaitMind {
  const build = (node: OutlineNode): MindElement => {
    const element = createMindElement(node.text || "未命名节点", {});
    element.children = node.children.map(build);
    return element;
  };

  const mind = createMindElement(root.text || "中心主题", {
    layout: MindLayoutType.right,
  }) as PlaitMind;
  mind.isRoot = true;
  mind.type = "mindmap";
  mind.points = [[0, 0]] as Point[];
  mind.children = root.children.map(build);
  return mind;
}

function parseOpmlOutlineNode(element: Element): OutlineNode {
  const text =
    normalizeText(element.getAttribute("text")) ||
    normalizeText(element.getAttribute("title")) ||
    "未命名节点";

  return {
    text,
    children: getDirectChildrenByTag(element, "outline").map(
      parseOpmlOutlineNode
    ),
  };
}

function parseOpmlToMind(xmlText: string, fallbackTitle: string): PlaitMind {
  const document = parseXmlDocument(xmlText, "OPML");
  const body = document.getElementsByTagName("body")[0];
  if (!body) {
    throw new Error("OPML body not found");
  }

  const headTitle = normalizeText(
    document.getElementsByTagName("title")[0]?.textContent
  );
  const topOutlines = getDirectChildrenByTag(body, "outline").map(
    parseOpmlOutlineNode
  );
  if (topOutlines.length === 0) {
    throw new Error("OPML outline not found");
  }

  const root =
    topOutlines.length === 1
      ? topOutlines[0]
      : {
          text: headTitle || fallbackTitle || "OPML 思维导图",
          children: topOutlines,
        };

  return createMindFromOutline(root);
}

function getFreeMindNodeText(element: Element) {
  const attrText = normalizeText(element.getAttribute("TEXT"));
  if (attrText) {
    return attrText;
  }

  const richContent = getDirectChildrenByTag(element, "richcontent").find(
    (child) => (child.getAttribute("TYPE") || "").toUpperCase() === "NODE"
  );
  return normalizeText(richContent?.textContent) || "未命名节点";
}

function parseFreeMindNode(element: Element): OutlineNode {
  return {
    text: getFreeMindNodeText(element),
    children: getDirectChildrenByTag(element, "node").map(parseFreeMindNode),
  };
}

function parseFreeMindToMind(xmlText: string): PlaitMind {
  const document = parseXmlDocument(xmlText, "FreeMind");
  const rootElement = document.documentElement;
  const rootNode =
    rootElement.tagName.toLowerCase() === "map"
      ? getDirectChildrenByTag(rootElement, "node")[0]
      : rootElement.tagName.toLowerCase() === "node"
        ? rootElement
        : null;

  if (!rootNode) {
    throw new Error("FreeMind root node not found");
  }

  return createMindFromOutline(parseFreeMindNode(rootNode));
}

async function parseOutlineFileToMind(
  file: File,
  fallbackTitle = getMindMapImportTitle(file.name)
): Promise<PlaitElement & { points?: Point[] }> {
  const format = detectMindMapImportFormat(file);
  if (!format) {
    throw new Error("Unsupported mind map import file");
  }


  const fileText = await file.text();
  if (!fileText.trim()) {
    throw new Error("Mind map import file is empty");
  }

  if (format === "markdown") {
    const { parseMarkdownToDrawnix } = await import(
      "@plait-board/markdown-to-drawnix"
    );
    return parseMarkdownToDrawnix(
      fileText,
      hasMarkdownHeading(fileText) ? undefined : fallbackTitle
    ) as unknown as PlaitElement & { points?: Point[] };
  }

  if (format === "opml") {
    return parseOpmlToMind(fileText, fallbackTitle) as PlaitElement & {
      points?: Point[];
    };
  }

  return parseFreeMindToMind(fileText) as PlaitElement & { points?: Point[] };
}

/** Preserve workbook sheets rather than flattening them into the topic tree. */
export async function parseMindMapFileToDocument(
  file: File,
  fallbackTitle = getMindMapImportTitle(file.name)
): Promise<ImportedMindMap> {
  if (detectMindMapImportFormat(file) === "xmind")
    return importXmind(file, fallbackTitle);
  const mind = await parseOutlineFileToMind(file, fallbackTitle);
  return {
    sheets: [
      {
        id: `import-${crypto.randomUUID()}`,
        title: "画布 1",
        children: [
          { ...mind, points: mind.points?.length ? mind.points : [[0, 0]] },
        ],
      },
    ],
    warnings: [],
  };
}