/**
 * Platform detection and automatic adapter selection
 */

import type { SecureStorageAdapter, SecureStorageOptions } from "./types";
import { MemorySecureStorage } from "./memory";
import { WebSecureStorage } from "./web";

/**
 * Detected platform
 */
export type Platform = "react-native" | "expo" | "web" | "node" | "unknown";

/**
 * Detect the current platform
 */
export function detectPlatform(): Platform {
  // Check for React Native
  if (typeof navigator !== "undefined" && navigator.product === "ReactNative") {
    // Check for Expo
    try {
      // @ts-ignore - dynamic require
      const Constants = require("expo-constants");
      if (Constants?.expoConfig) return "expo";
    } catch {
      // Not Expo
    }
    return "react-native";
  }
  
  // Check for Node.js
  if (typeof process !== "undefined" && process.versions?.node) {
    return "node";
  }
  
  // Check for browser
  if (typeof window !== "undefined" && typeof document !== "undefined") {
    return "web";
  }
  
  return "unknown";
}

/**
 * Create the best available secure storage adapter for the current platform
 */
export async function createSecureStorage(
  options: SecureStorageOptions = {}
): Promise<SecureStorageAdapter> {
  const platform = detectPlatform();
  
  switch (platform) {
    case "react-native":
      // Try to use react-native-keychain
      try {
        const { ReactNativeKeychainStorage } = await import("./rn-keychain");
        const adapter = new ReactNativeKeychainStorage(options);
        if (adapter.available) return adapter;
      } catch {
        // Keychain not available
      }
      // Fall through to memory
      console.warn("STYX: react-native-keychain not available, using memory storage");
      return new MemorySecureStorage(options);
      
    case "expo":
      // Try to use expo-secure-store
      try {
        const { ExpoSecureStorage } = await import("./expo-secure-store");
        const adapter = new ExpoSecureStorage(options);
        if (adapter.available) return adapter;
      } catch {
        // SecureStore not available
      }
      console.warn("STYX: expo-secure-store not available, using memory storage");
      return new MemorySecureStorage(options);
      
    case "web":
      const webStorage = new WebSecureStorage(options);
      if (webStorage.available) {
        await webStorage.init();
        return webStorage;
      }
      console.warn("STYX: Web Crypto not available, using memory storage");
      return new MemorySecureStorage(options);
      
    case "node":
      // Node.js - use memory storage (or could implement file-based)
      console.warn("STYX: Using memory storage in Node.js environment");
      return new MemorySecureStorage(options);
      
    default:
      return new MemorySecureStorage(options);
  }
}

/**
 * Check if secure storage is available on this platform
 */
export function isSecureStorageAvailable(): boolean {
  const platform = detectPlatform();
  
  switch (platform) {
    case "react-native":
    case "expo":
      return true; // Assume keychain/keystore is available on mobile
    case "web":
      return typeof window?.crypto?.subtle !== "undefined";
    default:
      return false;
  }
}