import { useEffect, useMemo, useState } from "react";
import { fmtRelative, useT, type Key } from "../i18n";
import { navigate } from "../router";
import { useStore, getState } from "../store";
import { cycleThemeMode } from "../theme";
import { Icon } from "./Icon";

interface Item {
  id: string;
  icon: string;
  label: string;
  hint?: string;
  keys?: string;
  run: () => void;
}

const basename = (p: string) => p.replace(/\/+$/, "").split("/").pop() || p;
const isMac = /Mac|iPhone|iPad/.test(navigator.platform);
export const MOD = isMac ? "⌘" : "Ctrl";

/** Root sessions, most recent first. */
function recent() {
  return getState()
    .sessions.filter((s) => !s.parent_id)
    .sort((a, b) => b.updated_at - a.updated_at);
}

/** Move to the next/previous session relative to the open one. */
function step(dir: 1 | -1) {
  const list = recent();
  const cur = location.hash.match(/^#\/s\/([^/+]+)/)?.[1];
  const i = list.findIndex((s) => s.id === cur);
  const next = list[i < 0 ? 0 : Math.min(Math.max(i + dir, 0), list.length - 1)];
  if (next) navigate(`/s/${next.id}`);
}

/** Global keyboard shortcuts and the command palette (Ctrl/⌘+K). */
export function Palette() {
  const t = useT();
  const [open, setOpen] = useState(false);
  const [q, setQ] = useState("");
  const [active, setActive] = useState(0);
  const sessions = useStore((s) => s.sessions);
  const isAdmin = useStore((s) => s.me?.role === "admin");

  useEffect(() => {
    const h = (e: KeyboardEvent) => {
      const mod = e.ctrlKey || e.metaKey;
      if (mod && !e.shiftKey && !e.altKey && e.key.toLowerCase() === "k") {
        e.preventDefault();
        setOpen((o) => !o);
        setQ("");
        setActive(0);
      } else if (e.altKey && !mod && e.key.toLowerCase() === "n") {
        e.preventDefault();
        navigate("/new");
      } else if (e.altKey && !mod && (e.key === "ArrowUp" || e.key === "ArrowDown")) {
        e.preventDefault();
        step(e.key === "ArrowUp" ? -1 : 1);
      } else if (mod && e.key === ",") {
        e.preventDefault();
        navigate("/settings");
      }
    };
    window.addEventListener("keydown", h);
    return () => window.removeEventListener("keydown", h);
  }, []);

  const items = useMemo<Item[]>(() => {
    const nav = (id: string, icon: string, label: Key, path: string, keys?: string): Item => ({ id, icon, label: t(label), keys, run: () => navigate(path) });
    const actions: Item[] = [
      nav("new", "plus", "palette.newSession", "/new", "Alt+N"),
      nav("files", "folder", "nav.files", "/files"),
      nav("terminal", "terminal", "nav.terminal", "/terminal"),
      nav("jobs", "clock", "nav.jobs", "/jobs"),
      nav("images", "image", "nav.images", "/images"),
      nav("stats", "chart", "nav.stats", "/stats"),
      nav("settings", "gear", "nav.settings", "/settings", `${MOD}+,`),
      nav("templates", "template", "templates.manage", "/settings/templates"),
      nav("account", "user", "settings.tab.account", "/settings/account"),
      ...(isAdmin
        ? [nav("providers", "brain", "settings.tab.providers", "/settings/providers"), nav("agents", "robot", "settings.tab.agents", "/settings/agents"), nav("users", "users", "settings.tab.users", "/settings/users")]
        : []),
      { id: "theme", icon: "theme-auto", label: t("palette.toggleTheme"), run: () => cycleThemeMode() },
    ];
    const sess: Item[] = sessions
      .filter((s) => !s.parent_id)
      .sort((a, b) => Number(!!a.archived) - Number(!!b.archived) || b.updated_at - a.updated_at)
      .map((s) => ({ id: s.id, icon: "file-text", label: s.title || t("session.untitled"), hint: `${basename(s.cwd)} · ${fmtRelative(s.updated_at)}`, run: () => navigate(`/s/${s.id}`) }));
    const needle = q.trim().toLowerCase();
    // Empty query: new session, the most recent sessions, then everything else.
    if (!needle) return [actions[0], ...sess.slice(0, 5), ...actions.slice(1)];
    const match = (x: Item) => `${x.label} ${x.hint ?? ""}`.toLowerCase().includes(needle);
    return [...actions.filter(match), ...sess.filter(match).slice(0, 30)];
  }, [q, sessions, isAdmin, t]);

  if (!open) return null;
  const run = (x?: Item) => {
    if (!x) return;
    setOpen(false);
    x.run();
  };
  const close = () => setOpen(false);

  return (
    <div className="modal-backdrop palette-backdrop" onClick={close}>
      <div className="modal palette" role="dialog" aria-label={t("palette.title")} onClick={(e) => e.stopPropagation()}>
        <input
          autoFocus
          value={q}
          placeholder={t("palette.placeholder")}
          onChange={(e) => (setQ(e.target.value), setActive(0))}
          onKeyDown={(e) => {
            if (e.key === "Escape") close();
            else if (e.key === "ArrowDown") (e.preventDefault(), setActive((a) => Math.min(a + 1, items.length - 1)));
            else if (e.key === "ArrowUp") (e.preventDefault(), setActive((a) => Math.max(a - 1, 0)));
            else if (e.key === "Enter") (e.preventDefault(), run(items[active]));
          }}
        />
        <div className="palette-list" role="listbox">
          {items.length === 0 && <div className="empty" style={{ padding: 16 }}>{t("palette.nothing")}</div>}
          {items.map((x, i) => (
            <button
              key={x.id}
              role="option"
              aria-selected={i === active}
              className={i === active ? "active" : ""}
              onMouseEnter={() => setActive(i)}
              onClick={() => run(x)}
              ref={i === active ? (el) => el?.scrollIntoView({ block: "nearest" }) : undefined}
            >
              <Icon name={x.icon} />
              <span className="palette-label">{x.label}</span>
              {x.hint && <span className="palette-hint">{x.hint}</span>}
              {x.keys && <kbd>{x.keys}</kbd>}
            </button>
          ))}
        </div>
        <div className="palette-foot">
          <span><kbd><Icon name="arrow-up" className="tiny" /></kbd><kbd><Icon name="arrow-down" className="tiny" /></kbd> {t("palette.move")}</span>
          <span><kbd>Enter</kbd> {t("palette.open")}</span>
          <span><kbd>Alt+<Icon name="arrow-up" className="tiny" /></kbd><kbd>Alt+<Icon name="arrow-down" className="tiny" /></kbd> {t("palette.prevNext")}</span>
          <span><kbd>Esc</kbd> {t("palette.close")}</span>
        </div>
      </div>
    </div>
  );
}