import { useCallback, useEffect, useState } from "react";
import { openUrl } from "@tauri-apps/plugin-opener";
import { api, LibraryCard, LibraryFilter, News, SetCard, SetInfo } from "../api";
import {
  CardCriteriaFields,
  CardTile,
  ColorToggles,
  QtyStepper,
  TileColumnsControl,
  applyCardCriteria,
  useCardCriteria,
  useTileColumns,
} from "../components";
import { useBackButton } from "../backButton";

/** Sets whose release date is still ahead of us, newest-announced first. */
function splitByRelease(sets: SetInfo[]): { upcoming: SetInfo[]; released: SetInfo[] } {
  const today = new Date().toISOString().slice(0, 10);
  const upcoming = sets.filter((s) => s.released_at !== null && s.released_at > today).reverse();
  const released = sets.filter((s) => s.released_at === null || s.released_at <= today);
  return { upcoming, released };
}

function formatDate(iso: string | null): string {
  if (!iso) return "Date TBA";
  const d = new Date(`${iso}T00:00:00`);
  return Number.isNaN(d.getTime())
    ? iso
    : d.toLocaleDateString(undefined, { year: "numeric", month: "short", day: "numeric" });
}

/** Date split for the timeline gutter, so every row's name starts at the same x. */
function dateParts(iso: string | null): { top: string; bottom: string } {
  if (!iso) return { top: "TBA", bottom: "" };
  const d = new Date(`${iso}T00:00:00`);
  if (Number.isNaN(d.getTime())) return { top: iso, bottom: "" };
  return {
    top: d.toLocaleDateString(undefined, { month: "short", day: "numeric" }),
    bottom: String(d.getFullYear()),
  };
}

function formatAge(fetchedAt: number): string {
  if (!fetchedAt) return "not loaded yet";
  const mins = Math.floor((Date.now() / 1000 - fetchedAt) / 60);
  if (mins < 2) return "just now";
  if (mins < 60) return `${mins} minutes ago`;
  const hours = Math.floor(mins / 60);
  if (hours < 24) return `${hours} hour${hours === 1 ? "" : "s"} ago`;
  const days = Math.floor(hours / 24);
  return `${days} day${days === 1 ? "" : "s"} ago`;
}

/** How many sets to show before "Show more" — a full list is 500+ rows. */
const RELEASED_PAGE = 12;

/**
 * What's happening in Magic outside your own collection: set releases you can
 * add cards from, and links to Wizards' latest articles.
 *
 * The two halves are deliberately independent. Releases come from Scryfall's
 * documented API; articles are scraped from a page with no supported feed, so
 * that section is allowed to fail on its own without taking the page with it.
 */
export function NewsView() {
  const [news, setNews] = useState<News | null>(null);
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [showAll, setShowAll] = useState(false);

  const [openSet, setOpenSet] = useState<SetInfo | null>(null);
  const [cards, setCards] = useState<(LibraryCard | SetCard)[] | null>(null);
  // Where a set's cards come from. "local" reads downloaded card data, which is
  // what makes the criteria filters possible; "live" queries Scryfall directly
  // for a set that isn't in reference.db yet — an upcoming or newly-released
  // one — which can't be filtered, so the panel is hidden rather than shown
  // doing nothing. Null while we work out which.
  const [source, setSource] = useState<"local" | "live" | null>(null);
  const [cardsError, setCardsError] = useState<string | null>(null);
  const tiles = useTileColumns();
  // The same criteria the Library and Card Search panels use — the set browser
  // runs through search_reference rather than its own path, so every filter
  // works here identically instead of being reimplemented.
  const [setText, setSetText] = useState("");
  const [setColors, setSetColors] = useState(0);
  const [setColorless, setSetColorless] = useState(false);
  const [setCriteria, patchSetCriteria] = useCardCriteria("news-set-criteria");

  const load = useCallback(async (refresh: boolean) => {
    setBusy(true);
    setError(null);
    try {
      setNews(await api.getNews(refresh));
    } catch (err) {
      setError(String(err));
    } finally {
      setBusy(false);
    }
  }, []);

  useEffect(() => {
    load(false);
  }, [load]);

  // Android back from a set's card list returns to the news, like the
  // "Back to news" button.
  useBackButton(() => setOpenSet(null), !!openSet);

  function openSetBrowser(set: SetInfo) {
    setOpenSet(set);
    setCards(null);
    setCardsError(null);
    setSource(null);
  }

  // Decide the source once per set, with an *unfiltered* probe: asking whether
  // the current criteria match anything would flip a perfectly indexed set to
  // "live" the moment a filter excluded everything.
  useEffect(() => {
    if (!openSet) return;
    let cancelled = false;
    setSource(null);
    api
      .searchReference({ set_code: openSet.code }, 1)
      .then((r) => !cancelled && setSource(r.length > 0 ? "local" : "live"))
      .catch(() => !cancelled && setSource("live"));
    return () => {
      cancelled = true;
    };
  }, [openSet]);

  // Not in the downloaded card data: fetch the set straight from Scryfall so an
  // upcoming set is still browsable, just without filters.
  useEffect(() => {
    if (!openSet || source !== "live") return;
    let cancelled = false;
    api
      .getSetCards(openSet.code)
      .then((r) => {
        if (cancelled) return;
        setCards(r);
        setCardsError(null);
      })
      .catch((e) => {
        if (cancelled) return;
        setCards([]);
        setCardsError(String(e));
      });
    return () => {
      cancelled = true;
    };
  }, [openSet, source]);

  // Refetch whenever the set or any criterion changes, debounced like the other
  // filter panels so typing doesn't fire a query per keystroke.
  useEffect(() => {
    if (!openSet || source !== "local") return;
    const filter: LibraryFilter = {
      set_code: openSet.code,
      text: setText.trim() || null,
      colors_include: setColors || null,
      colorless_colors: setColorless,
      ...applyCardCriteria(setCriteria),
    };
    let cancelled = false;
    const t = setTimeout(() => {
      api
        .searchReference(filter, 500)
        .then((r) => {
          if (cancelled) return;
          setCards(r);
          setCardsError(null);
        })
        .catch((e) => {
          if (cancelled) return;
          setCards([]);
          setCardsError(String(e));
        });
    }, 120);
    return () => {
      cancelled = true;
      clearTimeout(t);
    };
  }, [openSet, source, setText, setColors, setColorless, setCriteria]);

  async function adjust(oracleId: string, delta: number) {
    const qty = await api.addOwned(oracleId, delta);
    setCards((cs) =>
      cs ? cs.map((c) => (c.oracle_id === oracleId ? { ...c, quantity_owned: qty } : c)) : cs,
    );
  }

  // --- a set's cards ------------------------------------------------------
  if (openSet) {
    return (
      <div>
        <div className="page-header">
          <h2 className="page-header-title">
            {openSet.name}
            {cards && <span className="badge">{cards.length}</span>}
          </h2>
          <div className="page-header-actions">
            <TileColumnsControl tiles={tiles} />
            <button onClick={() => setOpenSet(null)}>← Back to news</button>
          </div>
        </div>
        <div className="hint">
          {formatDate(openSet.released_at)} · {openSet.set_type.replace(/_/g, " ")} · set code{" "}
          {openSet.code.toUpperCase()}
        </div>

        {/* Filters run against downloaded card data, so they only exist in
            "local" mode. Showing a panel that silently does nothing would be
            worse than not showing one. */}
        {source === "local" && (
        <div className="panel workspace">
          <div className="filters">
            <div className="field">
              <label>Name contains</label>
              <input
                value={setText}
                onChange={(e) => setSetText(e.target.value)}
                placeholder="e.g. bolt"
              />
            </div>
            <div className="field">
              <label>Includes colors</label>
              <ColorToggles
                value={setColors}
                onChange={setSetColors}
                colorless={setColorless}
                onColorlessChange={setSetColorless}
                colorlessTitle="Colorless cards only"
              />
            </div>
            <CardCriteriaFields value={setCriteria} onChange={patchSetCriteria} />
          </div>
        </div>
        )}

        {source === "live" && (
          <p className="hint">
            This set isn't in your downloaded card data yet, so it's being read
            straight from Scryfall — filters aren't available here. Run{" "}
            <strong>Update card data</strong> once it's out to filter it like the
            rest.
          </p>
        )}
        {cardsError ? (
          <p className="hint">{cardsError}</p>
        ) : !cards || source === null ? (
          <p className="hint">Loading cards…</p>
        ) : cards.length === 0 ? (
          <p className="hint">
            {source === "local"
              ? "No cards match these filters."
              : "No cards listed for this set yet."}
          </p>
        ) : (
          <div {...tiles.gridProps} style={{ ...tiles.gridProps.style, marginTop: "var(--space-4)" }}>
            {cards.map((c) => (
              <CardTile
                key={c.oracle_id}
                card={c}
                corner={
                  <QtyStepper
                    overlay
                    value={c.quantity_owned}
                    onDecrement={() => adjust(c.oracle_id, -1)}
                    onIncrement={() => adjust(c.oracle_id, 1)}
                  />
                }
              />
            ))}
          </div>
        )}
      </div>
    );
  }

  // --- the feed -----------------------------------------------------------
  const { upcoming, released } = splitByRelease(news?.sets ?? []);
  const shown = showAll ? released : released.slice(0, RELEASED_PAGE);

  const setRow = (s: SetInfo, upcoming = false) => {
    const { top, bottom } = dateParts(s.released_at);
    return (
      <li
        key={s.code}
        className={`set-row ${upcoming ? "upcoming" : ""}`}
        onClick={() => openSetBrowser(s)}
      >
        {/* Fixed-width date gutter: every set name then starts at the same x,
            which is what turns this from a list into a timeline. */}
        <span className="set-date">
          <span className="set-date-day">{top}</span>
          <span className="set-date-year">{bottom}</span>
        </span>
        {s.icon_uri ? (
          <img className="set-icon" src={s.icon_uri} alt="" loading="lazy" />
        ) : (
          <span className="set-icon" />
        )}
        <span className="set-row-main">
          <span className="set-name">{s.name}</span>
          <span className="set-row-meta">
            {s.set_type.replace(/_/g, " ")} · {s.card_count.toLocaleString()} cards
          </span>
        </span>
      </li>
    );
  };

  return (
    <div>
      <div className="page-header">
        <h2 className="page-header-title">News</h2>
        <div className="page-header-actions">
          <button onClick={() => load(true)} disabled={busy}>
            {busy ? "Refreshing…" : "Refresh"}
          </button>
        </div>
      </div>

      {error && <p className="hint">{error}</p>}
      {news && (
        <div className="hint">
          Updated {formatAge(news.fetched_at)}
          {news.fetched_at === 0 && " — check your connection"}
        </div>
      )}

      {!news && !error && <p className="hint">Loading…</p>}

      {news && (
        <div className="news-columns">
          <section className="news-col">
            <h3 className="group-header">Releases</h3>
            {news.sets.length === 0 ? (
              <p className="hint">Couldn't load set releases.</p>
            ) : (
              <>
                {upcoming.length > 0 && (
                  <>
                    <div className="section-label">Upcoming</div>
                    <ul className="result-list set-list">{upcoming.map((s) => setRow(s, true))}</ul>
                  </>
                )}
                <div className="section-label" style={{ marginTop: "var(--space-4)" }}>
                  Released
                </div>
                <ul className="result-list set-list">{shown.map((s) => setRow(s))}</ul>
                {released.length > shown.length && (
                  <div className="row" style={{ marginTop: "var(--space-3)" }}>
                    <button onClick={() => setShowAll(true)}>
                      Show all {released.length} sets
                    </button>
                  </div>
                )}
              </>
            )}
          </section>

          <section className="news-col">
            <h3 className="group-header">Latest from Wizards</h3>
            {/* This half has no supported feed, so it's expected to break
                eventually. Say so plainly and leave releases alone. */}
            {news.articles.length === 0 ? (
              <p className="hint">
                {news.articles_ok
                  ? "No articles found."
                  : "Couldn't load the latest news right now."}
              </p>
            ) : (
              <>
                {!news.articles_ok && (
                  <p className="hint">Showing the last articles we could load.</p>
                )}
                <ul className="result-list article-list">
                  {news.articles.map((a) => (
                    <li key={a.url} onClick={() => openUrl(a.url)} title={a.url}>
                      {/* Fixed-width so titles line up; the categories are a
                          small closed set, not free text. */}
                      <span className="article-cat">{a.category.replace(/-/g, " ")}</span>
                      <span className="article-title">{a.title}</span>
                    </li>
                  ))}
                </ul>
                <p className="hint">Articles open on magic.wizards.com.</p>
              </>
            )}
          </section>
        </div>
      )}
    </div>
  );
}