import { LocalStorage } from "@raycast/api";
import { randomUUID } from "node:crypto";
import { getPreferences } from "./preferences";
import type { PlaceholderMapping, SessionMode, VelumSession } from "./types";

const SESSIONS_STORAGE_KEY = "velum.sessions.v1";
const ACTIVE_SESSION_STORAGE_KEY = "velum.sessions.active.v1";

function nowIso(): string {
  return new Date().toISOString();
}

function dayKey(date = new Date()): string {
  return date.toISOString().slice(0, 10);
}

function sessionSort(a: VelumSession, b: VelumSession): number {
  return Date.parse(b.updatedAt) - Date.parse(a.updatedAt);
}

async function saveSessions(sessions: VelumSession[]): Promise<void> {
  const maxSessions = getPreferences().maxSessions;
  const pruned = [...sessions].sort(sessionSort).slice(0, maxSessions);
  await LocalStorage.setItem(SESSIONS_STORAGE_KEY, JSON.stringify(pruned));

  const activeId = await getActiveSessionId();
  if (activeId && !pruned.some((session) => session.id === activeId)) {
    await LocalStorage.setItem(ACTIVE_SESSION_STORAGE_KEY, pruned[0]?.id ?? "");
  }
}

export async function listSessions(): Promise<VelumSession[]> {
  const raw = await LocalStorage.getItem<string>(SESSIONS_STORAGE_KEY);
  if (!raw) {
    return [];
  }

  try {
    return (JSON.parse(raw) as VelumSession[]).sort(sessionSort);
  } catch {
    await LocalStorage.removeItem(SESSIONS_STORAGE_KEY);
    return [];
  }
}

export async function getActiveSessionId(): Promise<string | undefined> {
  const id = await LocalStorage.getItem<string>(ACTIVE_SESSION_STORAGE_KEY);
  return id || undefined;
}

export async function setActiveSession(id: string): Promise<void> {
  await LocalStorage.setItem(ACTIVE_SESSION_STORAGE_KEY, id);
}

export async function createSession(name?: string): Promise<VelumSession> {
  const timestamp = nowIso();
  const session: VelumSession = {
    id: randomUUID(),
    name: name || `Sitzung ${new Date().toLocaleString()}`,
    createdAt: timestamp,
    updatedAt: timestamp,
    mapping: {},
  };

  const sessions = await listSessions();
  await saveSessions([session, ...sessions]);
  await setActiveSession(session.id);
  return session;
}

export async function getSession(
  id: string,
): Promise<VelumSession | undefined> {
  const sessions = await listSessions();
  return sessions.find((session) => session.id === id);
}

export async function getActiveSession(): Promise<VelumSession> {
  const sessions = await listSessions();
  const activeId = await getActiveSessionId();
  const active = sessions.find((session) => session.id === activeId);
  if (active) {
    return active;
  }
  return createSession();
}

export async function resolveSessionForMode(
  mode: SessionMode,
): Promise<VelumSession> {
  if (mode === "new-each-request") {
    return createSession(`Anfrage ${new Date().toLocaleString()}`);
  }

  if (mode === "daily") {
    const name = `Tag ${dayKey()}`;
    const existing = (await listSessions()).find(
      (session) => session.name === name,
    );
    if (existing) {
      await setActiveSession(existing.id);
      return existing;
    }
    return createSession(name);
  }

  return getActiveSession();
}

export async function resolveDefaultSession(): Promise<VelumSession> {
  return resolveSessionForMode(getPreferences().sessionMode);
}

export async function updateSessionMapping(
  id: string,
  mapping: PlaceholderMapping,
  entityTypes?: string[],
): Promise<VelumSession> {
  const sessions = await listSessions();
  const timestamp = nowIso();
  const index = sessions.findIndex((session) => session.id === id);

  if (index === -1) {
    const created: VelumSession = {
      id,
      name: `Sitzung ${new Date().toLocaleString()}`,
      createdAt: timestamp,
      updatedAt: timestamp,
      mapping,
      entityTypes,
    };
    await saveSessions([created, ...sessions]);
    return created;
  }

  const updated: VelumSession = {
    ...sessions[index],
    mapping,
    entityTypes,
    updatedAt: timestamp,
  };
  const next = [...sessions];
  next[index] = updated;
  await saveSessions(next);
  return updated;
}

export async function renameSession(id: string, name: string): Promise<void> {
  const sessions = await listSessions();
  await saveSessions(
    sessions.map((session) =>
      session.id === id
        ? { ...session, name: name.trim() || session.name, updatedAt: nowIso() }
        : session,
    ),
  );
}

export async function clearSessionMapping(id: string): Promise<void> {
  const sessions = await listSessions();
  await saveSessions(
    sessions.map((session) =>
      session.id === id
        ? { ...session, mapping: {}, updatedAt: nowIso() }
        : session,
    ),
  );
}

export async function deleteSession(id: string): Promise<void> {
  const sessions = await listSessions();
  const next = sessions.filter((session) => session.id !== id);
  await saveSessions(next);

  const activeId = await getActiveSessionId();
  if (activeId === id) {
    if (next[0]) {
      await setActiveSession(next[0].id);
    } else {
      await LocalStorage.removeItem(ACTIVE_SESSION_STORAGE_KEY);
    }
  }
}

export async function deleteAllSessions(): Promise<void> {
  await LocalStorage.removeItem(SESSIONS_STORAGE_KEY);
  await LocalStorage.removeItem(ACTIVE_SESSION_STORAGE_KEY);
}

export function countMappingEntries(mapping: PlaceholderMapping): number {
  return Object.keys(mapping).length;
}