using System.Security.Claims;
using System.Text.Encodings.Web;
using Microsoft.AspNetCore.Authentication;
using Microsoft.Extensions.Options;

namespace pages;

public class FixedTokenAuthenticationHandler : AuthenticationHandler<AuthenticationSchemeOptions> {
    private readonly IConfiguration _configuration;

    public FixedTokenAuthenticationHandler(IOptionsMonitor<AuthenticationSchemeOptions> options, ILoggerFactory logger,
        UrlEncoder encoder, IConfiguration configuration) : base(options, logger, encoder) {
        _configuration = configuration;
    }

    protected override Task<AuthenticateResult> HandleAuthenticateAsync() {
        string? token = _configuration["API_TOKEN"];

        if (string.IsNullOrEmpty(token))
            throw new ArgumentException("API_TOKEN not found.");

        if (!Request.Headers.TryGetValue("Authorization", out var headerValue))
            return Task.FromResult(AuthenticateResult.Fail("No Authorization header."));

        string providedToken = headerValue.ToString().Replace("Bearer ", "");
        if (providedToken != token)
            return Task.FromResult(AuthenticateResult.Fail("Invalid token."));

        var identity = new ClaimsIdentity([], Scheme.Name);
        var principal = new ClaimsPrincipal(identity);
        var ticket = new AuthenticationTicket(principal, Scheme.Name);

        return Task.FromResult(AuthenticateResult.Success(ticket));
    }
}