using System.Net;
using System.Net.Http;
using System.Text;
using System.Text.Json;

namespace DocumentService.Tests.Unit.Client;

/// <summary>
/// Reusable fake <see cref="HttpMessageHandler"/> for unit-testing HTTP clients.
/// Captures the outgoing request and returns the configured response.
/// </summary>
internal sealed class MockHttpMessageHandler : HttpMessageHandler
{
    private readonly HttpResponseMessage _response;

    /// <summary>The last request that was sent through this handler.</summary>
    public HttpRequestMessage? LastRequest { get; private set; }

    public MockHttpMessageHandler(HttpResponseMessage response)
    {
        _response = response;
    }

    // ?? convenience factories ????????????????????????????????????????????????

    /// <summary>Creates a handler that returns 200 OK with a JSON-serialised body.</summary>
    public static MockHttpMessageHandler ReturningJson<T>(T body, HttpStatusCode status = HttpStatusCode.OK)
    {
        var json = JsonSerializer.Serialize(body, new JsonSerializerOptions { PropertyNamingPolicy = JsonNamingPolicy.CamelCase });
        var response = new HttpResponseMessage(status)
        {
            Content = new StringContent(json, Encoding.UTF8, "application/json")
        };
        return new MockHttpMessageHandler(response);
    }

    /// <summary>Creates a handler that returns 200 OK with raw bytes as the body.</summary>
    public static MockHttpMessageHandler ReturningBytes(byte[] bytes, string mediaType = "application/octet-stream", HttpStatusCode status = HttpStatusCode.OK)
    {
        var response = new HttpResponseMessage(status)
        {
            Content = new ByteArrayContent(bytes) { Headers = { ContentType = new(mediaType) } }
        };
        return new MockHttpMessageHandler(response);
    }

    /// <summary>Creates a handler that returns the given status code with no body.</summary>
    public static MockHttpMessageHandler ReturningStatus(HttpStatusCode status)
        => new(new HttpResponseMessage(status));

    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        LastRequest = request;
        return Task.FromResult(_response);
    }
}