import fs from 'node:fs';

import { BrowserWindow, safeStorage } from 'electron';

import { ipcChannels } from '../../shared/ipc/contracts';
import { EULA_CURRENT_VERSION } from '../../shared/license/eulaVersion';
import type { LicenseSnapshot } from '../../shared/license/licenseSnapshot';
import type { LicensePayloadV1 } from '../../shared/license/payloadV1';

import { getOrCreateDeviceId } from './deviceId';
import { licenseEncryptedPath, preferencesPath } from './paths';
import { verifyLicenseToken } from './verifyLicenseToken';

type Preferences = {
  eulaAcceptedVersion?: number;
};

function readPreferences(userData: string): Preferences {
  try {
    const raw = fs.readFileSync(preferencesPath(userData), 'utf8');
    return JSON.parse(raw) as Preferences;
  } catch {
    return {};
  }
}

function writePreferences(userData: string, prefs: Preferences): void {
  fs.mkdirSync(userData, { recursive: true });
  fs.writeFileSync(preferencesPath(userData), `${JSON.stringify(prefs, null, 2)}\n`, 'utf8');
}

function emitLicenseStatusChanged(): void {
  for (const win of BrowserWindow.getAllWindows()) {
    win.webContents.send(ipcChannels.license.statusChanged, {});
  }
}

export class LicenseService {
  private readonly userData: string;
  private readonly deviceId: string;
  private lastRemoteRevokeCheckMs = 0;
  private lastRemoteRevoked = false;

  constructor(userData: string) {
    this.userData = userData;
    this.deviceId = getOrCreateDeviceId(userData);
  }

  private isSkipLicense(): boolean {
    return process.env.DND_SKIP_LICENSE === '1' || process.env.DND_SKIP_LICENSE === 'true';
  }

  private readSealedToken(): string | null {
    const p = licenseEncryptedPath(this.userData);
    if (!fs.existsSync(p)) return null;
    if (!safeStorage.isEncryptionAvailable()) {
      throw new Error('safeStorage недоступен: нельзя расшифровать лицензию на этой системе');
    }
    const buf = fs.readFileSync(p);
    return safeStorage.decryptString(buf);
  }

  private writeSealedToken(token: string): void {
    if (!safeStorage.isEncryptionAvailable()) {
      throw new Error('safeStorage недоступен: нельзя сохранить лицензию на этой системе');
    }
    fs.mkdirSync(this.userData, { recursive: true });
    const enc = safeStorage.encryptString(token);
    fs.writeFileSync(licenseEncryptedPath(this.userData), enc);
  }

  private clearSealedTokenFile(): void {
    try {
      fs.unlinkSync(licenseEncryptedPath(this.userData));
    } catch {
      /* ok */
    }
  }

  private async maybeRefreshRemoteRevocation(payload: LicensePayloadV1): Promise<void> {
    const base = process.env.DND_LICENSE_STATUS_URL?.trim();
    if (!base) return;
    const now = Date.now();
    if (now - this.lastRemoteRevokeCheckMs < 60_000) return;
    this.lastRemoteRevokeCheckMs = now;
    try {
      const u = new URL('v1/status', base.endsWith('/') ? base : `${base}/`);
      u.searchParams.set('sub', payload.sub);
      const res = await fetch(u, { method: 'GET', signal: AbortSignal.timeout(8000) });
      if (!res.ok) return;
      const j = (await res.json()) as { revoked?: boolean };
      this.lastRemoteRevoked = Boolean(j.revoked);
    } catch {
      /* offline: не блокируем */
    }
  }

  getStatusSync(): LicenseSnapshot {
    if (this.isSkipLicense()) {
      return {
        active: true,
        devSkip: true,
        reason: 'ok',
        summary: null,
        eulaAcceptedVersion: readPreferences(this.userData).eulaAcceptedVersion ?? null,
        deviceId: this.deviceId,
      };
    }

    const eulaAcceptedVersion = readPreferences(this.userData).eulaAcceptedVersion ?? null;
    const nowSec = Math.floor(Date.now() / 1000);
    let token: string | null = null;
    try {
      token = this.readSealedToken();
    } catch {
      return {
        active: false,
        devSkip: false,
        reason: 'none',
        summary: null,
        eulaAcceptedVersion,
        deviceId: this.deviceId,
      };
    }
    if (!token?.trim()) {
      return {
        active: false,
        devSkip: false,
        reason: 'none',
        summary: null,
        eulaAcceptedVersion,
        deviceId: this.deviceId,
      };
    }

    const v = verifyLicenseToken(token, { nowSec, deviceId: this.deviceId });
    if (!v.ok) {
      return {
        active: false,
        devSkip: false,
        reason: v.reason,
        summary: null,
        eulaAcceptedVersion,
        deviceId: this.deviceId,
      };
    }

    if (this.lastRemoteRevoked) {
      return {
        active: false,
        devSkip: false,
        reason: 'revoked_remote',
        summary: {
          sub: v.payload.sub,
          pid: v.payload.pid,
          exp: v.payload.exp,
          did: v.payload.did,
        },
        eulaAcceptedVersion,
        deviceId: this.deviceId,
      };
    }

    return {
      active: true,
      devSkip: false,
      reason: 'ok',
      summary: {
        sub: v.payload.sub,
        pid: v.payload.pid,
        exp: v.payload.exp,
        did: v.payload.did,
      },
      eulaAcceptedVersion,
      deviceId: this.deviceId,
    };
  }

  async getStatus(): Promise<LicenseSnapshot> {
    if (this.isSkipLicense()) return this.getStatusSync();
    const base = this.getStatusSync();
    if (!base.active || !base.summary) return base;
    const token = this.readSealedToken();
    if (!token?.trim()) return base;
    const v = verifyLicenseToken(token, {
      nowSec: Math.floor(Date.now() / 1000),
      deviceId: this.deviceId,
    });
    if (!v.ok) return this.getStatusSync();
    await this.maybeRefreshRemoteRevocation(v.payload);
    return this.getStatusSync();
  }

  setToken(token: string): LicenseSnapshot {
    if (this.isSkipLicense()) {
      return this.getStatusSync();
    }
    const trimmed = token.trim();
    const nowSec = Math.floor(Date.now() / 1000);
    const v = verifyLicenseToken(trimmed, { nowSec, deviceId: this.deviceId });
    if (!v.ok) {
      throw new Error(`LICENSE_INVALID:${v.reason}`);
    }
    this.writeSealedToken(trimmed);
    this.lastRemoteRevoked = false;
    emitLicenseStatusChanged();
    return this.getStatusSync();
  }

  clearToken(): LicenseSnapshot {
    this.clearSealedTokenFile();
    this.lastRemoteRevoked = false;
    emitLicenseStatusChanged();
    return this.getStatusSync();
  }

  acceptEula(version: number): { ok: true } {
    if (version !== EULA_CURRENT_VERSION) {
      throw new Error('EULA_BAD_VERSION');
    }
    const prefs = readPreferences(this.userData);
    prefs.eulaAcceptedVersion = version;
    writePreferences(this.userData, prefs);
    emitLicenseStatusChanged();
    return { ok: true };
  }

  assertForIpc(): void {
    if (this.isSkipLicense()) return;
    const s = this.getStatusSync();
    if (!s.active) {
      throw new Error(`LICENSE_REQUIRED:${s.reason}`);
    }
  }
}