import { apiFetch } from "./api.js";
import { dom } from "./dom.js";
import { state } from "./state.js";

function escapeHtml(text) {
  return text
    .replaceAll("&", "&")
    .replaceAll("<", "&lt;")
    .replaceAll(">", "&gt;");
}

function slugify(text) {
  return text
    .toLowerCase()
    .trim()
    .replace(/[^\w\u4e00-\u9fa5]+/g, "-")
    .replace(/^-+|-+$/g, "");
}

function parseMarkdown(text) {
  const lines = text.split(/\r?\n/);
  const blocks = [];
  const headings = [];
  let inCode = false;
  let codeBuffer = [];
  let paragraph = [];

  const flushParagraph = () => {
    if (!paragraph.length) {
      return;
    }
    blocks.push(`<p>${escapeHtml(paragraph.join(" "))}</p>`);
    paragraph = [];
  };

  const flushCode = () => {
    if (!codeBuffer.length) {
      return;
    }
    blocks.push(`<pre><code>${escapeHtml(codeBuffer.join("\n"))}</code></pre>`);
    codeBuffer = [];
  };

  lines.forEach((line) => {
    if (line.startsWith("```")) {
      if (inCode) {
        flushCode();
      } else {
        flushParagraph();
      }
      inCode = !inCode;
      return;
    }

    if (inCode) {
      codeBuffer.push(line);
      return;
    }

    const heading = line.match(/^(#{1,4})\s+(.*)$/);
    if (heading) {
      flushParagraph();
      const level = heading[1].length;
      const textValue = heading[2].trim();
      const id = slugify(textValue);
      headings.push({ level, text: textValue, id });
      blocks.push(`<h${level} id="${id}">${escapeHtml(textValue)}</h${level}>`);
      return;
    }

    if (!line.trim()) {
      flushParagraph();
      return;
    }

    paragraph.push(line.trim());
  });

  flushParagraph();
  flushCode();

  return { html: blocks.join(""), headings };
}

export async function loadApiDoc() {
  const text = await apiFetch("/api/docs/api-md");
  const { html, headings } = parseMarkdown(text || "");

  dom.apiDocContent.innerHTML = html || "<p>API.md 为空</p>";
  dom.apiDocToc.innerHTML = headings.length
    ? headings
        .map(
          (item) =>
            `<a class="doc-toc-item level-${item.level}" href="#${item.id}">${escapeHtml(item.text)}</a>`,
        )
        .join("")
    : "<div class=\"muted\">未解析到标题</div>";

  dom.apiDocToc.querySelectorAll("a").forEach((link) => {
    link.addEventListener("click", (event) => {
      event.preventDefault();
      const id = link.getAttribute("href")?.slice(1);
      if (!id) {
        return;
      }
      const target = dom.apiDocContent.querySelector(`#${CSS.escape(id)}`);
      if (target) {
        const offset = target.getBoundingClientRect().top - dom.apiDocContent.getBoundingClientRect().top;
        dom.apiDocContent.scrollBy({ top: offset, behavior: "smooth" });
      }
    });
  });

  state.apiDocLoaded = true;
}

export async function openApiDocDrawer() {
  dom.apiDocDrawer.classList.remove("hidden");
  if (!state.apiDocLoaded) {
    await loadApiDoc();
  }
}

export function closeApiDocDrawer() {
  dom.apiDocDrawer.classList.add("hidden");
}