/**
 * Patch: add datalist autocomplete to the <tag-input-field> web component.
 *
 * Fetches /micropub?q=category&filter=<value> as the user types (debounced
 * 300ms) and populates a native <datalist>. Selecting a suggestion fills the
 * text field; the user confirms with comma or blur as usual.
 *
 * Datalist is explicitly cleared in keydown(Comma) and blur handlers because
 * the existing handlers clear the field via programmatic .value = "" which
 * does NOT fire the input event (HTML Living Standard).
 */

import { access, readFile, writeFile } from "node:fs/promises";

const MARKER = "// [patch] tag-input-autocomplete";

const candidates = [
  "node_modules/@indiekit/frontend/components/tag-input/index.js",
  "node_modules/@indiekit/indiekit/node_modules/@indiekit/frontend/components/tag-input/index.js",
];

const OLD_SNIPPET = `    // Capture any value in input not converted to tag (for example, by clicking
    // outside component before pressing tab key) and add to list of tags.
    $tagInputInput.addEventListener("blur", () => {
      if ($tagInputInput.value) {
        tagInput.addTag($tagInputInput.value, false);
        $tagInputInput.value = "";
      }
    });

    return tagInput;`;

const NEW_SNIPPET = `    // Capture any value in input not converted to tag (for example, by clicking
    // outside component before pressing tab key) and add to list of tags.
    $tagInputInput.addEventListener("blur", () => {
      if ($tagInputInput.value) {
        tagInput.addTag($tagInputInput.value, false);
        $tagInputInput.value = "";
      }
    });

    // Autocomplete: wire datalist to Micropub q=category endpoint ${MARKER}
    const _micropubHref =
      document.querySelector('link[rel="micropub"]')?.href ?? "/micropub";
    const _datalistId =
      "tag-suggestions-" + (this.$replacedInput?.getAttribute("name") ?? Math.random().toString(36).slice(2));
    const _$datalist = document.createElement("datalist");
    _$datalist.id = _datalistId;
    this.appendChild(_$datalist);
    $tagInputInput.setAttribute("list", _datalistId);

    let _autocompleteTimer;
    $tagInputInput.addEventListener("input", () => {
      clearTimeout(_autocompleteTimer);
      const _val = $tagInputInput.value.trim();
      if (!_val) { _$datalist.replaceChildren(); return; }
      _autocompleteTimer = setTimeout(async () => {
        try {
          const _res = await fetch(
            \`\${_micropubHref}?q=category&filter=\${encodeURIComponent(_val)}\`
          );
          if (!_res.ok) return;
          const _data = await _res.json();
          _$datalist.replaceChildren(
            ...(_data.categories ?? []).map((_cat) => {
              const _opt = document.createElement("option");
              _opt.value = _cat;
              return _opt;
            })
          );
        } catch {}
      }, 300);
    });

    // Clear datalist after tag confirmed via comma (programmatic clear doesn't fire input)
    $tagInputInput.addEventListener("keydown", (_e) => {
      if (_e.code === "Comma") _$datalist.replaceChildren();
    });

    // Clear datalist after tag confirmed via blur
    $tagInputInput.addEventListener("blur", () => {
      _$datalist.replaceChildren();
    });

    return tagInput;`;

async function exists(p) {
  try { await access(p); return true; } catch { return false; }
}

let totalPatched = 0;
let totalChecked = 0;

for (const filePath of candidates) {
  if (!(await exists(filePath))) continue;
  totalChecked++;

  const source = await readFile(filePath, "utf8");
  if (source.includes(MARKER)) {
    console.log(`[postinstall] patch-tag-input-autocomplete: already applied to ${filePath}`);
    continue;
  }

  if (!source.includes(OLD_SNIPPET)) {
    console.warn(`[postinstall] patch-tag-input-autocomplete: snippet not found in ${filePath} (upstream changed?)`);
    continue;
  }

  const updated = source.replace(OLD_SNIPPET, NEW_SNIPPET);
  await writeFile(filePath, updated, "utf8");
  console.log(`[postinstall] Applied patch-tag-input-autocomplete to ${filePath}`);
  totalPatched++;
}

if (totalChecked === 0) {
  console.log("[postinstall] patch-tag-input-autocomplete: no target files found");
} else if (totalPatched === 0) {
  console.log("[postinstall] patch-tag-input-autocomplete: already up to date");
} else {
  console.log(`[postinstall] patch-tag-input-autocomplete: patched ${totalPatched} file(s)`);
}