---
// Light client-side filter for the blog archive.
// Reads [data-search] attributes on rows + the featured article, hides
// non-matches, collapses empty year heads, toggles a no-results message.
// Filter script is added in Task 5; this file ships markup + styles only.
---

<div class="bsearch">
  <input
    type="search"
    class="binput"
    aria-label="Search posts"
    placeholder="Search the journal…"
    autocomplete="off"
    spellcheck="false"
  />
  <span class="bhint" aria-hidden="true">Esc to clear</span>
</div>

<style>
  /* No border-bottom: the adjacent .feature article carries a border-top
     that already separates this row from the page below. */
  .bsearch {
    display: flex;
    align-items: baseline;
    gap: 14px;
    padding: clamp(14px, 2.4vh, 22px) 0;
    border-top: 1px solid var(--hairline-on-dark);
  }
  :global(body:not(.dark)) .bsearch {
    border-top-color: var(--hairline);
  }
  .binput {
    flex: 1;
    max-width: 28ch;
    background: transparent;
    border: 0;
    border-bottom: 1px solid transparent;
    padding: 6px 0;
    font-family: var(--font-mono);
    font-size: 13px;
    color: var(--fg-on-dark-1);
    letter-spacing: 0.02em;
    outline: none;
    transition: border-color var(--dur-base) var(--ease-out);
  }
  :global(body:not(.dark)) .binput {
    color: var(--fg-1);
  }
  .binput::placeholder {
    color: var(--fg-on-dark-3);
  }
  :global(body:not(.dark)) .binput::placeholder {
    color: var(--fg-3);
  }
  .binput:focus {
    border-bottom-color: var(--accent);
  }
  .bhint {
    font-family: var(--font-mono);
    font-size: 11px;
    color: var(--fg-on-dark-3);
    letter-spacing: 0.06em;
    opacity: 0;
    transition: opacity var(--dur-base) var(--ease-out);
  }
  :global(body:not(.dark)) .bhint {
    color: var(--fg-3);
  }
  .bsearch:focus-within .bhint {
    opacity: 1;
  }

  @media (max-width: 800px) {
    .binput {
      max-width: none;
    }
    .bhint {
      display: none;
    }
  }
</style>

<script>
  // Lives on /blog. No-ops gracefully on any other page (selectors return empty).
  const input = document.querySelector<HTMLInputElement>(".binput");
  if (input) {
    const rows = Array.from(
      document.querySelectorAll<HTMLElement>("[data-search]")
    );
    const featured = document.querySelector<HTMLElement>("[data-featured]");
    const yearHeads = Array.from(
      document.querySelectorAll<HTMLElement>("[data-year-head]")
    );
    const empty = document.querySelector<HTMLElement>("[data-empty]");
    const emptyQuery = empty?.querySelector<HTMLElement>("[data-empty-query]");

    function applyFilter() {
      const raw = input!.value.toLowerCase().trim();
      const tokens = raw.length ? raw.split(/\s+/) : [];
      const isFiltering = tokens.length > 0;

      let visibleCount = 0;
      for (const row of rows) {
        const haystack = row.dataset.search ?? "";
        const isFeatured = row === featured;
        let visible: boolean;
        if (!isFiltering) {
          visible = true;
        } else if (isFeatured) {
          // Featured hides whenever there's a query, regardless of match.
          visible = false;
        } else {
          visible = tokens.every((t) => haystack.includes(t));
        }
        row.classList.toggle("is-hidden", !visible);
        if (visible && !isFeatured) visibleCount += 1;
      }

      // Hide year heads whose following rows are all hidden.
      for (const head of yearHeads) {
        let anyVisible = false;
        let node: Element | null = head.nextElementSibling;
        while (node && !node.matches("[data-year-head]")) {
          if (node.matches("[data-search]") && !node.classList.contains("is-hidden")) {
            anyVisible = true;
            break;
          }
          node = node.nextElementSibling;
        }
        head.classList.toggle("is-hidden", !anyVisible);
      }

      // Toggle empty-state message.
      if (empty) {
        const showEmpty = isFiltering && visibleCount === 0;
        empty.hidden = !showEmpty;
        if (showEmpty && emptyQuery) emptyQuery.textContent = input!.value.trim();
      }
    }

    input.addEventListener("input", applyFilter);

    // `/` from anywhere on the page focuses the search input — unless the user
    // is already typing somewhere editable (text input, textarea, or any
    // contenteditable element). `Esc` while the input is focused clears the
    // query, blurs, and restores the full archive.
    document.addEventListener("keydown", (event) => {
      if (event.key === "/" && !event.metaKey && !event.ctrlKey && !event.altKey) {
        const target = event.target as HTMLElement | null;
        const tag = target?.tagName;
        const editable =
          tag === "INPUT" ||
          tag === "TEXTAREA" ||
          target?.isContentEditable === true;
        if (!editable) {
          event.preventDefault();
          input!.focus();
        }
      } else if (event.key === "Escape" && document.activeElement === input) {
        if (input!.value !== "") {
          input!.value = "";
          applyFilter();
        }
        input!.blur();
      }
    });
  }
</script>