// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Rewrite.Logging;
 
namespace Microsoft.AspNetCore.Rewrite;
 
internal sealed class RedirectToNonWwwRule : IRule
{
    private const string WwwDot = "www.";
 
    private readonly string[]? _domains;
    private readonly int _statusCode;
 
    public RedirectToNonWwwRule(int statusCode)
    {
        _statusCode = statusCode;
    }
 
    public RedirectToNonWwwRule(int statusCode, params string[] domains)
    {
        ArgumentNullException.ThrowIfNull(domains);
 
        if (domains.Length < 1)
        {
            throw new ArgumentException($"One or more {nameof(domains)} must be provided.");
        }
 
        _domains = domains;
        _statusCode = statusCode;
    }
 
    public void ApplyRule(RewriteContext context)
    {
        var request = context.HttpContext.Request;
 
        var hostInDomains = RedirectToWwwHelper.IsHostInDomains(request, _domains);
 
        if (!hostInDomains)
        {
            context.Result = RuleResult.ContinueRules;
            return;
        }
 
        if (!request.Host.HasValue || !request.Host.Value.StartsWith(WwwDot, StringComparison.OrdinalIgnoreCase))
        {
            context.Result = RuleResult.ContinueRules;
            return;
        }
 
        RedirectToWwwHelper.SetRedirect(
            context,
            new HostString(request.Host.Value.Substring(4)), // We verified the hostname begins with "www." already.
            _statusCode);
 
        context.Logger.RedirectedToNonWww();
    }
}