/**
 * AWS Configuration for Cognito-based S3 access
 * 
 * This module handles AWS credentials through Cognito Identity Provider.
 * No AWS credentials are stored in code or exposed to the client.
 * 
 * Environment Variables Required:
 * - VITE_AWS_REGION: AWS region (e.g., "us-east-2")
 * - VITE_AWS_COGNITO_IDENTITY_POOL_ID: Cognito Identity Pool ID (e.g., "us-east-2:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx")
 * - VITE_S3_BUCKET: Default S3 bucket name (e.g., "ddy-first-bucket")
 */

import { S3Client, GetObjectCommand } from "@aws-sdk/client-s3";
import { fromCognitoIdentityPool } from "@aws-sdk/credential-provider-cognito-identity";
import { CognitoIdentityClient } from "@aws-sdk/client-cognito-identity";

export const AWS_REGION = import.meta.env.VITE_AWS_REGION || "us-east-2";
// Cognito pool ID is safe to embed in client code (not a secret)
export const COGNITO_IDENTITY_POOL_ID = import.meta.env.VITE_AWS_COGNITO_IDENTITY_POOL_ID || "us-east-2:1387102d-5a87-4742-8a69-1baa70f37984";
export const DEFAULT_BUCKET = import.meta.env.VITE_S3_BUCKET || "ddy-first-bucket";

/**
 * Initialize S3 client with Cognito credentials
 * Uses unauthenticated Cognito Identity pool for public S3 access
 */
export function getS3Client() {
  const credentialsProvider = fromCognitoIdentityPool({
    client: new CognitoIdentityClient({ region: AWS_REGION }),
    identityPoolId: COGNITO_IDENTITY_POOL_ID,
  });

  return new S3Client({
    region: AWS_REGION,
    credentials: credentialsProvider,
  });
}

/**
 * Get S3 object as text (for JSON tilesets, metadata, etc.)
 */
export async function getS3ObjectAsText(bucket, key) {
  const s3Client = getS3Client();
  if (!s3Client) {
    throw new Error("S3 client not initialized");
  }

  try {
    const command = new GetObjectCommand({
      Bucket: bucket,
      Key: key,
    });

    const response = await s3Client.send(command);
    const text = await response.Body.transformToString();
    return text;
  } catch (error) {
    console.error(`Failed to fetch S3 object s3://${bucket}/${key}:`, error);
    throw error;
  }
}

/**
 * Get S3 object as JSON
 */
export async function getS3ObjectAsJson(bucket, key) {
  const text = await getS3ObjectAsText(bucket, key);
  return JSON.parse(text);
}

/**
 * Build a direct S3 URL for tile assets
 * Note: This URL requires proper CORS configuration on S3 bucket
 * or the bucket must be public with proper authentication
 */
export function buildS3Url(bucket, key) {
  return `https://${bucket}.s3.${AWS_REGION}.amazonaws.com/${key}`;
}

/**
 * Rewrite URLs in a tileset JSON to use proper S3 paths
 * Handles both relative and absolute URLs
 */
export function rewriteTilesetUrls(tilesetJson, bucket, basePath) {
  const rewrite = (obj) => {
    if (!obj || typeof obj !== "object") return;

    if (Array.isArray(obj)) {
      obj.forEach(rewrite);
      return;
    }

    Object.keys(obj).forEach((key) => {
      const value = obj[key];

      // Rewrite uri/url fields to point to S3
      if ((key === "uri" || key === "url") && typeof value === "string") {
        // Skip external URLs
        if (value.startsWith("http://") || value.startsWith("https://")) {
          return;
        }

        // Skip data URLs
        if (value.startsWith("data:")) {
          return;
        }

        // Build S3 URL for relative paths
        const relativePath = value.startsWith("/") ? value.slice(1) : value;
        const s3Key = basePath
          ? `${basePath}/${relativePath}`.replace(/\/+/g, "/")
          : relativePath;

        obj[key] = buildS3Url(bucket, s3Key);
      }

      // Recursively rewrite nested objects
      if (typeof value === "object") {
        rewrite(value);
      }
    });
  };

  rewrite(tilesetJson);
  return tilesetJson;
}

/**
 * Load a tileset JSON file from S3 and rewrite its URLs
 */
export async function loadTilesetFromS3(bucket, tilesetPath, basePath) {
  try {
    const tilesetJson = await getS3ObjectAsJson(bucket, tilesetPath);
    return rewriteTilesetUrls(tilesetJson, bucket, basePath);
  } catch (error) {
    console.error(`Failed to load tileset from S3:`, error);
    throw error;
  }
}

/**
 * Get default S3 bucket name
 */
export function getDefaultBucket() {
  return DEFAULT_BUCKET;
}

/**
 * Get AWS region
 */
export function getAwsRegion() {
  return AWS_REGION;
}

/**
 * Validate AWS configuration
 */
export function validateAwsConfig() {
  return !!(AWS_REGION && COGNITO_IDENTITY_POOL_ID && DEFAULT_BUCKET);
}