import { cycleThemeMode, getThemeMode, onThemeChange } from "../theme";
import { useMemo, useSyncExternalStore } from "react";
import { post } from "../api";
import { fmtRelative, useT, type Key } from "../i18n";
import { navigate } from "../router";
import { useStore } from "../store";
import type { Session } from "../types";

function basename(p: string) {
  return p.split("/").filter(Boolean).pop() ?? p;
}

function groupKey(ms: number): Key {
  const day = 86400000;
  const startOfToday = new Date().setHours(0, 0, 0, 0);
  if (ms >= startOfToday) return "sidebar.today";
  if (ms >= startOfToday - day) return "sidebar.yesterday";
  if (ms >= startOfToday - 7 * day) return "sidebar.week";
  return "sidebar.older";
}

export function Sidebar({ open, activeId, section }: { open: boolean; activeId?: string; section: string }) {
  const t = useT();
  const sessions = useStore((s) => s.sessions);
  const busy = useStore((s) => s.busy);
  const connected = useStore((s) => s.connected);
  const permissions = useStore((s) => s.permissions);
  const questions = useStore((s) => s.questions);
  const me = useStore((s) => s.me);

  const attention = useMemo(() => {
    const ids = new Set<string>();
    for (const p of permissions) ids.add(p.root_session_id ?? p.session_id);
    for (const q of questions) ids.add(q.root_session_id ?? q.session_id);
    return ids;
  }, [permissions, questions]);

  const groups = useMemo(() => {
    const out: { key: Key; items: Session[] }[] = [];
    for (const s of sessions) {
      const key = groupKey(s.updated_at);
      const g = out.find((x) => x.key === key);
      if (g) g.items.push(s);
      else out.push({ key, items: [s] });
    }
    return out;
  }, [sessions]);

  return (
    <aside className={`sidebar ${open ? "open" : ""}`}>
      <div className="sidebar-head">
        <div className="logo">
          <img src="/icon.svg" alt="" />
          CodeCraft
        </div>
        <span className={`conn-dot ${connected ? "on" : ""}`} title={connected ? t("sidebar.connected") : t("sidebar.disconnected")} />
      </div>
      <div style={{ padding: "0 12px 8px" }}>
        <button className="primary" style={{ width: "100%" }} onClick={() => navigate("/new")}>
          + {t("sidebar.newSession")}
        </button>
      </div>
      <nav className="session-list">
        {sessions.length === 0 && <div className="empty">{t("sidebar.noSessions")}</div>}
        {groups.map((g) => (
          <div key={g.key}>
            <div className="session-group">{t(g.key)}</div>
            {g.items.map((s) => (
              <button
                key={s.id}
                className={`session-item ${s.id === activeId ? "active" : ""}`}
                onClick={() => navigate(`/s/${s.id}`)}
              >
                <div className="title">
                  {attention.has(s.id) ? <i className="attn-dot" title={t("sidebar.needsInput")} /> : busy[s.id] && <i className="busy-ring" title={t("activity.working")} />}
                  <span>{s.title || t("session.untitled")}</span>
                </div>
                <div className="sub">
                  {s.shared && <span title={t("sidebar.shared")}>⇄ </span>}
                  {basename(s.cwd)} · {s.agent} · {fmtRelative(s.updated_at)}
                </div>
              </button>
            ))}
          </div>
        ))}
      </nav>
      <div className="sidebar-user">
        <span title={me?.username}>
          {me?.display_name || me?.username}
          {me?.role === "admin" && <span className="chip" style={{ marginLeft: 6 }}>admin</span>}
        </span>
        <ThemeModeButton />
        <button className="small ghost" onClick={() => post("/auth/logout").then(() => location.reload())}>
          <span className="nav-icon" aria-hidden>🚪</span>
          {t("nav.logout")}
        </button>
      </div>
      <div className="sidebar-foot">
        <button className={`ghost ${section === "files" ? "active" : ""}`} onClick={() => navigate("/files")}>
          <span className="nav-icon" aria-hidden>📁</span>
          {t("nav.files")}
        </button>
        <button className={`ghost ${section === "images" ? "active" : ""}`} onClick={() => navigate("/images")}>
          <span className="nav-icon" aria-hidden>🖼️</span>
          {t("nav.images")}
        </button>
        <button className={`ghost ${section === "stats" ? "active" : ""}`} onClick={() => navigate("/stats")}>
          <span className="nav-icon" aria-hidden>📊</span>
          {t("nav.stats")}
        </button>
        <button className={`ghost ${section === "settings" ? "active" : ""}`} onClick={() => navigate("/settings")}>
          <span className="nav-icon" aria-hidden>🔧</span>
          {t("nav.settings")}
        </button>
      </div>
    </aside>
  );
}

/** Quick light/dark/auto switcher. */
function ThemeModeButton() {
  const t = useT();
  const mode = useSyncExternalStore(onThemeChange, getThemeMode);
  const icon = mode === "auto" ? "◐" : mode === "light" ? "☀" : "☾";
  const label = t(mode === "auto" ? "settings.themeAuto" : mode === "light" ? "settings.themeLight" : "settings.themeDark");
  return (
    <button className="small ghost theme-toggle" onClick={cycleThemeMode} title={`${t("settings.themeToggle")} – ${label}`} aria-label={t("settings.themeToggle")}>
      {icon}
    </button>
  );
}