using System.IO;
using System.Security.Cryptography;
using System.Text;
using Newtonsoft.Json;
using System;
using System.Net.Http;
using System.Net;
using System.Threading.Tasks;

public class Script : ScriptBase
{
    public override async Task<HttpResponseMessage> ExecuteAsync()
    {
        HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);

        // Read the request body
        string requestBody = await this.Context.Request.Content.ReadAsStringAsync();
        Console.WriteLine($"Request Body: {requestBody}");
        var input = JsonConvert.DeserializeObject<InputPayload>(requestBody);

        // Check if plainText is provided
        if (string.IsNullOrEmpty(input.PlainText))
        {
            response.StatusCode = HttpStatusCode.BadRequest;
            response.Content = CreateJsonContent("{\"error\": \"String parameter is required.\"}");
            return response;
        }

        // Encrypt the plain text using SHA-256
        string encryptedText = CreateSHA256(input.PlainText, input.Key);

        // Log the plain text and encrypted text
        Console.WriteLine($"Plain Text: {input.PlainText}");
        Console.WriteLine($"Encrypted Text: {encryptedText}");

        // Create JSON response
        var jsonResponse = new
        {
            message = "The text has been encrypted using SHA-256.",
            encryptedText = encryptedText
        };

        response.Content = CreateJsonContent(JsonConvert.SerializeObject(jsonResponse));
        return response;
    }

    public static string CreateSHA256(string input, string key)
    {
        using (SHA256 sha256 = SHA256.Create())
        {
            byte[] keyBytes = Encoding.UTF8.GetBytes(key);
            byte[] inputBytes = Encoding.UTF8.GetBytes(input);
            byte[] combinedBytes = new byte[keyBytes.Length + inputBytes.Length];

            Buffer.BlockCopy(keyBytes, 0, combinedBytes, 0, keyBytes.Length);
            Buffer.BlockCopy(inputBytes, 0, combinedBytes, keyBytes.Length, inputBytes.Length);

            byte[] hashBytes = sha256.ComputeHash(combinedBytes);

            // Convert the byte array to hexadecimal string
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < hashBytes.Length; i++)
            {
                sb.Append(hashBytes[i].ToString("x2")); // Use "x2" for lowercase
            }

            return sb.ToString();
        }
    }

    private static StringContent CreateJsonContent(string json)
    {
        return new StringContent(json, Encoding.UTF8, "application/json");
    }
}

public class InputPayload
{
    public string PlainText { get; set; }
    public string Key { get; set; }
}