// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
#nullable enable
 
using System.Diagnostics;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.Extensions.Options;
 
namespace Microsoft.AspNetCore.Mvc.Infrastructure;
 
/// <summary>
/// The `DefaultProblemDetailsFactory` is a concrete implementation of the `ProblemDetailsFactory` abstract class.
/// It provides methods to create instances of `ProblemDetails` and `ValidationProblemDetails` with default settings.
/// This class uses the provided `ApiBehaviorOptions` for client error mapping and an optional custom configuration action to further customize the problem details.
/// </summary>
public sealed class DefaultProblemDetailsFactory : ProblemDetailsFactory
{
    private readonly ApiBehaviorOptions _options;
    private readonly Action<ProblemDetailsContext>? _configure;
 
    /// <summary>
    /// Initializes a new instance of the <see cref="DefaultProblemDetailsFactory"/> class.
    /// </summary>
    /// <param name="options">The options for API behavior.</param>
    /// <param name="problemDetailsOptions">The options for customizing problem details.</param>
    public DefaultProblemDetailsFactory(
        IOptions<ApiBehaviorOptions> options,
        IOptions<ProblemDetailsOptions>? problemDetailsOptions = null)
    {
        _options = options?.Value ?? throw new ArgumentNullException(nameof(options));
        _configure = problemDetailsOptions?.Value?.CustomizeProblemDetails;
    }
 
    
    /// <inheritdoc />
    public override ProblemDetails CreateProblemDetails(
        HttpContext httpContext,
        int? statusCode = null,
        string? title = null,
        string? type = null,
        string? detail = null,
        string? instance = null)
    {
        statusCode ??= 500;
 
        var problemDetails = new ProblemDetails
        {
            Status = statusCode,
            Title = title,
            Type = type,
            Detail = detail,
            Instance = instance,
        };
 
        ApplyProblemDetailsDefaults(httpContext, problemDetails, statusCode.Value);
 
        return problemDetails;
    }
 
    /// <inheritdoc />
    public override ValidationProblemDetails CreateValidationProblemDetails(
        HttpContext httpContext,
        ModelStateDictionary modelStateDictionary,
        int? statusCode = null,
        string? title = null,
        string? type = null,
        string? detail = null,
        string? instance = null)
    {
        ArgumentNullException.ThrowIfNull(modelStateDictionary);
 
        statusCode ??= 400;
 
        var problemDetails = new ValidationProblemDetails(modelStateDictionary)
        {
            Status = statusCode,
            Type = type,
            Detail = detail,
            Instance = instance,
        };
 
        if (title != null)
        {
            // For validation problem details, don't overwrite the default title with null.
            problemDetails.Title = title;
        }
 
        ApplyProblemDetailsDefaults(httpContext, problemDetails, statusCode.Value);
 
        return problemDetails;
    }
 
    private void ApplyProblemDetailsDefaults(HttpContext httpContext, ProblemDetails problemDetails, int statusCode)
    {
        problemDetails.Status ??= statusCode;
 
        if (_options.ClientErrorMapping.TryGetValue(statusCode, out var clientErrorData))
        {
            problemDetails.Title ??= clientErrorData.Title;
            problemDetails.Type ??= clientErrorData.Link;
        }
 
        var traceId = Activity.Current?.Id ?? httpContext?.TraceIdentifier;
        if (traceId != null)
        {
            problemDetails.Extensions["traceId"] = traceId;
        }
 
        _configure?.Invoke(new() { HttpContext = httpContext!, ProblemDetails = problemDetails });
    }
}