@using System.Security.Cryptography
@using System.Text
@using IdentityModel
@inject NavigationManager NavigationManager
@{
    var code_verifier = GenerateCodeVerifier();
    var code_challenge = GenerateCodeChallenge(code_verifier);

    var returnUrl = Uri.EscapeDataString(NavigationManager.Uri);
    var loginUrl = $"https://localhost:5001/connect/authorize" +
                   $"?client_id=dev" +
                   $"&response_type=code" +
                   $"&scope=openid%20profile%20verification" +
                   $"&redirect_uri=https://localhost:5137/authentication/login-callback" +
                   $"&state={returnUrl}" +
                   $"&code_challenge={code_challenge}" +
                   $"&code_challenge_method=S256";

    NavigationManager.NavigateTo(loginUrl, forceLoad: true);
}

@code {

    private static string GenerateCodeVerifier()
    {
        var provider = RandomNumberGenerator.Create();
        var byteArray = new byte[32];
        provider.GetBytes(byteArray);
        return Base64Url.Encode(byteArray);
    }

    private static string GenerateCodeChallenge(string codeVerifier)
    {
        var buffer = Encoding.UTF8.GetBytes(codeVerifier);
        var sha256 = SHA256.Create();
        return Base64Url.Encode(sha256.ComputeHash(buffer));
    }

}