import { Action, ActionPanel, Clipboard, Icon, List, useNavigation } from "@vicinae/api";
import { useCallback, useEffect, useMemo, useState } from "react";
import { runAutoDelete } from "./lib/cleanup";
import { ChatView } from "./lib/components/ChatView";
import { sessionToPlainText } from "./lib/markdown";
import { getLamPreferences } from "./lib/preferences";
import { clearSessions, deleteSession, listSessions, loadSession } from "./lib/sessions";
import type { SessionSummary } from "./lib/types";
import { formatRelativeTime, truncate } from "./lib/utils";

/**
 * Browse and manage past conversations.
 *
 * Loading a transcript is deferred until the user actually opens one: the
 * index holds only summaries, so this view stays fast no matter how much
 * history has piled up.
 */
export default function SessionsCommand() {
  const { push } = useNavigation();
  const [sessions, setSessions] = useState<SessionSummary[] | undefined>(undefined);
  const preferences = useMemo(() => getLamPreferences(), []);

  const refresh = useCallback(() => {
    void listSessions()
      .then(setSessions)
      .catch(() => setSessions([]));
  }, []);

  // Opening the list is the other moment the user is asking about their history,
  // so it is the other moment expired conversations should be gone. No `keepId`:
  // nothing is open here to spare. The refresh afterwards is what stops the list
  // rendering a row that was just deleted from underneath it.
  useEffect(() => {
    let cancelled = false;

    void (async () => {
      await runAutoDelete({ maxAgeMs: preferences.autoDeleteMs });
      if (!cancelled) refresh();
    })();

    return () => {
      cancelled = true;
    };
  }, [preferences.autoDeleteMs, refresh]);

  const openSession = useCallback(
    (id: string) => {
      void loadSession(id).then((session) => {
        if (session) push(<ChatView initialSession={session} />);
      });
    },
    [push],
  );

  const remove = useCallback(
    (id: string) => {
      void deleteSession(id).then(refresh);
    },
    [refresh],
  );

  const copyConversation = useCallback((id: string) => {
    // Loads the full transcript rather than copying the index preview.
    void loadSession(id).then((session) => {
      if (session) void Clipboard.copy(sessionToPlainText(session.turns));
    });
  }, []);

  const removeAll = useCallback(() => {
    void clearSessions().then(refresh);
  }, [refresh]);

  const loaded = sessions !== undefined;
  const items = sessions ?? [];

  return (
    <List
      isLoading={!loaded}
      navigationTitle="Chat Sessions"
      searchBarPlaceholder="Search conversations…"
    >
      {loaded && items.length === 0 ? (
        <List.EmptyView
          icon={Icon.SpeechBubble}
          title="No conversations yet"
          description="Open the chat command and ask something. Conversations are saved automatically."
        />
      ) : null}

      {items.map((summary) => (
        <List.Item
          key={summary.id}
          id={summary.id}
          icon={Icon.SpeechBubble}
          title={truncate(summary.title, 70)}
          subtitle={truncate(summary.preview, 90)}
          accessories={[{ text: `${summary.turnCount} turns` }, { text: formatRelativeTime(summary.updatedAt) }]}
          actions={
            <ActionPanel>
              <Action
                title="Open Conversation"
                icon={Icon.SpeechBubble}
                onAction={() => openSession(summary.id)}
              />
              <Action
                title="Copy Conversation"
                shortcut={{ key: "c", modifiers: ["cmd", "shift"] }}
                onAction={() => copyConversation(summary.id)}
              />
              <ActionPanel.Section title="Danger Zone">
                <Action
                  title="Delete Conversation"
                  icon={Icon.Trash}
                  style="destructive"
                  // Matches the chat view, so one shortcut means one thing across both commands.
                  shortcut={{ key: "backspace", modifiers: ["cmd", "shift"] }}
                  onAction={() => remove(summary.id)}
                />
                <Action
                  title="Delete All Conversations"
                  icon={Icon.Trash}
                  style="destructive"
                  onAction={removeAll}
                />
              </ActionPanel.Section>
            </ActionPanel>
          }
        />
      ))}
    </List>
  );
}