import { Pool } from "pg";
import type { OmniInboundEnvelopeV1 } from "./types";

const TELEGRAM_FILE_MARKER = "tg-file:";
const TELEGRAM_API_BASE_DEFAULT = "https://api.telegram.org";

type AvatarStateRow = {
  avatar_fingerprint: string | null;
};

function asString(value: unknown) {
  if (typeof value !== "string") return null;
  const normalized = value.trim();
  return normalized || null;
}

function requiredEnv(name: string) {
  const value = asString(process.env[name]);
  if (!value) {
    throw new Error(`${name} is required`);
  }
  return value;
}

function parseTelegramFileId(avatarUrl: string | null) {
  const raw = asString(avatarUrl);
  if (!raw || !raw.startsWith(TELEGRAM_FILE_MARKER)) return null;
  const fileId = raw.slice(TELEGRAM_FILE_MARKER.length).trim();
  return fileId || null;
}

function parseTelegramUserId(value: string | null) {
  const raw = asString(value);
  if (!raw || !/^\d+$/.test(raw)) return null;
  const userId = Number.parseInt(raw, 10);
  if (!Number.isFinite(userId) || userId <= 0) return null;
  return userId;
}

function telegramApiBase() {
  return asString(process.env.TELEGRAM_API_BASE) ?? TELEGRAM_API_BASE_DEFAULT;
}

type TelegramUserProfilePhotosResponse = {
  ok?: boolean;
  result?: {
    photos?: Array<Array<{ file_id?: string }>>;
  };
  description?: string;
};

function pickProfilePhotoFileId(payload: TelegramUserProfilePhotosResponse) {
  const groups = payload.result?.photos;
  if (!Array.isArray(groups) || !groups.length) return null;
  const firstGroup = groups[0];
  if (!Array.isArray(firstGroup) || !firstGroup.length) return null;

  for (let index = firstGroup.length - 1; index >= 0; index -= 1) {
    const fileId = asString(firstGroup[index]?.file_id);
    if (fileId) return fileId;
  }

  return null;
}

async function resolveProfileAvatarFileId(contactExternalId: string | null) {
  const userId = parseTelegramUserId(contactExternalId);
  if (!userId) return null;

  const token = asString(process.env.TELEGRAM_BOT_TOKEN);
  if (!token) return null;

  const response = await fetch(`${telegramApiBase().replace(/\/+$/, "")}/bot${token}/getUserProfilePhotos`, {
    method: "POST",
    headers: { "content-type": "application/json" },
    body: JSON.stringify({
      user_id: userId,
      offset: 0,
      limit: 1,
    }),
  });

  if (!response.ok) return null;
  const payload = (await response.json()) as TelegramUserProfilePhotosResponse;
  if (!payload.ok) return null;

  return pickProfilePhotoFileId(payload);
}

const pool = new Pool({
  connectionString: requiredEnv("TELEGRAM_PROFILE_STATE_DATABASE_URL"),
});

let initPromise: Promise<void> | null = null;

async function ensureInitialized() {
  if (!initPromise) {
    initPromise = pool
      .query(`
        CREATE TABLE IF NOT EXISTS telegram_contact_profile_state (
          contact_external_id TEXT PRIMARY KEY,
          avatar_fingerprint TEXT,
          avatar_file_id TEXT,
          updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
        )
      `)
      .then(() => undefined);
  }
  await initPromise;
}

async function detectAvatarChange(input: {
  contactExternalId: string | null;
  avatarFileId: string | null;
  avatarFingerprint: string | null;
}) {
  const contactExternalId = asString(input.contactExternalId);
  const avatarFileId = asString(input.avatarFileId);
  const avatarFingerprint = asString(input.avatarFingerprint) ?? avatarFileId;

  if (!contactExternalId || !avatarFileId || !avatarFingerprint) {
    return { changed: false };
  }

  await ensureInitialized();

  const row = await pool.query<AvatarStateRow>(
    `
      SELECT avatar_fingerprint
      FROM telegram_contact_profile_state
      WHERE contact_external_id = $1
    `,
    [contactExternalId],
  );
  const previousFingerprint = asString(row.rows[0]?.avatar_fingerprint);
  const changed = previousFingerprint !== avatarFingerprint;

  if (changed) {
    await pool.query(
      `
        INSERT INTO telegram_contact_profile_state (
          contact_external_id,
          avatar_fingerprint,
          avatar_file_id,
          updated_at
        )
        VALUES ($1, $2, $3, NOW())
        ON CONFLICT (contact_external_id) DO UPDATE SET
          avatar_fingerprint = EXCLUDED.avatar_fingerprint,
          avatar_file_id = EXCLUDED.avatar_file_id,
          updated_at = NOW()
      `,
      [contactExternalId, avatarFingerprint, avatarFileId],
    );
  }

  return { changed };
}

export async function applyAvatarProfileState(envelope: OmniInboundEnvelopeV1): Promise<OmniInboundEnvelopeV1> {
  const payload = envelope.payloadNormalized;
  const contactExternalId = asString(payload.contactExternalId);
  let contactAvatarUrl = asString(payload.contactAvatarUrl);
  let contactAvatarFingerprint = asString(payload.contactAvatarFingerprint);

  if (!contactAvatarUrl) {
    const profileFileId = await resolveProfileAvatarFileId(contactExternalId);
    if (profileFileId) {
      contactAvatarUrl = `${TELEGRAM_FILE_MARKER}${profileFileId}`;
      if (!contactAvatarFingerprint) {
        contactAvatarFingerprint = profileFileId;
      }
    }
  }

  const avatarFileId = parseTelegramFileId(contactAvatarUrl);

  const avatarState = await detectAvatarChange({
    contactExternalId,
    avatarFileId,
    avatarFingerprint: contactAvatarFingerprint,
  });

  return {
    ...envelope,
    payloadNormalized: {
      ...payload,
      contactAvatarChanged: avatarState.changed,
      contactAvatarUrl: avatarState.changed ? contactAvatarUrl : null,
      contactAvatarFingerprint,
    },
  };
}

export async function closeProfileState() {
  await pool.end();
}