import { computed, reactive, readonly, ref } from "vue";

export interface Person {
  id: string;
  name: string;
  handle: string;
  color: string;
  online: boolean;
  bio: string;
}

export interface Message {
  id: string;
  personId: string;
  body: string;
  sentAt: number;
  mine: boolean;
  status: "sent" | "delivered" | "failed";
}

export interface Conversation {
  id: string;
  personId: string;
  unread: number;
  pinned?: boolean;
  messages: Message[];
}

const people: Person[] = [
  {
    id: "maya",
    name: "Maya Chen",
    handle: "@mayac",
    color: "#ff7a8a",
    online: true,
    bio: "Product designer · Sydney to everywhere.",
  },
  {
    id: "noah",
    name: "Noah Williams",
    handle: "@noahw",
    color: "#4f9cff",
    online: true,
    bio: "Film, tiny cameras, and very long walks.",
  },
  {
    id: "sofia",
    name: "Sofia Rossi",
    handle: "@sofiar",
    color: "#9d67ff",
    online: false,
    bio: "Making typefaces and better pasta.",
  },
  {
    id: "liam",
    name: "Liam Park",
    handle: "@liamp",
    color: "#35c7a0",
    online: true,
    bio: "Engineer. Climber. Questionable DJ.",
  },
  {
    id: "amara",
    name: "Amara Okafor",
    handle: "@amarao",
    color: "#f4ad42",
    online: false,
    bio: "Architecture and cities after dark.",
  },
];

const timestamp = Date.now();
const seedConversations: Conversation[] = [
  {
    id: "maya",
    personId: "maya",
    unread: 2,
    pinned: true,
    messages: [
      {
        id: "m1",
        personId: "maya",
        body: "That transition feels ridiculously smooth ✨",
        sentAt: timestamp - 840_000,
        mine: false,
        status: "delivered",
      },
      {
        id: "m2",
        personId: "maya",
        body: "Try holding it halfway, then let go slowly.",
        sentAt: timestamp - 780_000,
        mine: false,
        status: "delivered",
      },
    ],
  },
  {
    id: "noah",
    personId: "noah",
    unread: 0,
    messages: [
      {
        id: "n1",
        personId: "noah",
        body: "Uploaded the photos from yesterday.",
        sentAt: timestamp - 4_200_000,
        mine: false,
        status: "delivered",
      },
      {
        id: "n2",
        personId: "noah",
        body: "The grain is perfect.",
        sentAt: timestamp - 4_000_000,
        mine: true,
        status: "delivered",
      },
    ],
  },
  {
    id: "sofia",
    personId: "sofia",
    unread: 1,
    messages: [
      {
        id: "s1",
        personId: "sofia",
        body: "Coffee at the new place tomorrow?",
        sentAt: timestamp - 18_000_000,
        mine: false,
        status: "delivered",
      },
    ],
  },
  {
    id: "liam",
    personId: "liam",
    unread: 0,
    messages: [
      {
        id: "l1",
        personId: "liam",
        body: "The build is green. Ship it.",
        sentAt: timestamp - 86_000_000,
        mine: false,
        status: "delivered",
      },
    ],
  },
  {
    id: "amara",
    personId: "amara",
    unread: 0,
    messages: [
      {
        id: "a1",
        personId: "amara",
        body: "This city never really goes quiet.",
        sentAt: timestamp - 172_000_000,
        mine: false,
        status: "delivered",
      },
    ],
  },
];

const conversations = ref<Conversation[]>(structuredClone(seedConversations));
const ready = ref(false);
const offline = ref(!navigator.onLine);
const settings = reactive({ simulatedLatency: 180, simulateFailures: false });

function openDatabase() {
  return new Promise<IDBDatabase>((resolve, reject) => {
    const request = indexedDB.open("native-vue-messenger", 1);
    request.onupgradeneeded = () => request.result.createObjectStore("state");
    request.onsuccess = () => resolve(request.result);
    request.onerror = () => reject(request.error);
  });
}

async function readStored() {
  const database = await openDatabase();
  return await new Promise<Conversation[] | undefined>((resolve, reject) => {
    const transaction = database.transaction("state", "readonly");
    const request = transaction.objectStore("state").get("conversations");
    request.onsuccess = () =>
      resolve(request.result as Conversation[] | undefined);
    request.onerror = () => reject(request.error);
  }).finally(() => database.close());
}

async function persist() {
  try {
    const database = await openDatabase();
    await new Promise<void>((resolve, reject) => {
      const transaction = database.transaction("state", "readwrite");
      transaction
        .objectStore("state")
        .put(structuredClone(conversations.value), "conversations");
      transaction.oncomplete = () => resolve();
      transaction.onerror = () => reject(transaction.error);
    });
    database.close();
  } catch {
    // Private browsing and locked-down webviews can reject IndexedDB.
  }
}

async function initialize() {
  try {
    const stored = await readStored();
    if (stored?.length) conversations.value = stored;
    else await persist();
  } finally {
    ready.value = true;
  }
}

window.addEventListener("online", () => {
  offline.value = false;
});
window.addEventListener("offline", () => {
  offline.value = true;
});
void initialize();

export function useDemoStore() {
  const conversationFor = (id: string) =>
    computed(() =>
      conversations.value.find((conversation) => conversation.id === id),
    );
  const personFor = (id: string) => people.find((person) => person.id === id);
  const markRead = (id: string) => {
    const conversation = conversations.value.find((item) => item.id === id);
    if (conversation) conversation.unread = 0;
    void persist();
  };
  const sendMessage = async (id: string, body: string) => {
    const conversation = conversations.value.find((item) => item.id === id);
    if (!conversation || !body.trim()) return false;
    const message: Message = {
      id: crypto.randomUUID(),
      personId: id,
      body: body.trim(),
      sentAt: Date.now(),
      mine: true,
      status: "sent",
    };
    conversation.messages.push(message);
    await persist();
    await new Promise((resolve) =>
      window.setTimeout(resolve, settings.simulatedLatency),
    );
    message.status =
      settings.simulateFailures || offline.value ? "failed" : "delivered";
    await persist();
    return message.status === "delivered";
  };
  const reset = async () => {
    conversations.value = structuredClone(seedConversations);
    await persist();
  };
  return {
    people: readonly(ref(people)),
    conversations: readonly(conversations),
    ready: readonly(ready),
    offline: readonly(offline),
    settings,
    conversationFor,
    personFor,
    markRead,
    sendMessage,
    reset,
  };
}

export function relativeTime(value: number) {
  const minutes = Math.floor((Date.now() - value) / 60_000);
  if (minutes < 1) return "now";
  if (minutes < 60) return `${minutes}m`;
  const hours = Math.floor(minutes / 60);
  if (hours < 24) return `${hours}h`;
  return `${Math.floor(hours / 24)}d`;
}