using System.Net;
using System.Net.Http.Json;
using Acl.Application;
using Acl.Infrastructure;

namespace Acl.Tests;

public class ObjectenGatewayTests
{
    private sealed class StubHandler(Func<HttpRequestMessage, Task<HttpResponseMessage>> onSend)
        : HttpMessageHandler
    {
        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken ct)
            => onSend(request);
    }

    private sealed class FixedClock(DateOnly today) : IClock
    {
        public DateOnly Today { get; } = today;
    }

    private sealed record Sent(
        HttpMethod Method, Uri Uri, string? Body, string? Auth, string? ContentCrs, string? AcceptCrs, long? ContentLength);

    private const string ObjecttypeUrl = "http://objecttypen:8000/api/v2/objecttypes/ot-1";

    private static ObjectenGateway Gateway(List<Sent> sent, Func<HttpRequestMessage, HttpResponseMessage> respond) =>
        new(
            new HttpClient(new StubHandler(async req =>
            {
                // Read the length BEFORE the body: ReadAsStringAsync buffers the content and would set
                // ContentLength as a side effect, masking whether the gateway buffered it itself (uwsgi
                // rejects a chunked body).
                sent.Add(new Sent(
                    req.Method,
                    req.RequestUri!,
                    ContentLength: req.Content?.Headers.ContentLength,
                    Body: req.Content is null ? null : await req.Content.ReadAsStringAsync(),
                    Auth: req.Headers.Authorization?.ToString(),
                    ContentCrs: req.Content?.Headers.TryGetValues("Content-Crs", out var c) == true ? string.Join(",", c!) : null,
                    AcceptCrs: req.Headers.TryGetValues("Accept-Crs", out var a) ? string.Join(",", a) : null));
                return respond(req);
            })),
            new ObjectenOptions
            {
                BaseUrl = new("http://objecten:8000"),
                Token = "objecten-token",
                ObjecttypenBaseUrl = new("http://objecttypen:8000"),
                ObjecttypenToken = "objecttypen-token",
                ObjecttypeName = "RegisterRecord",
            },
            new FixedClock(new DateOnly(2026, 6, 4)));

    // A stack that answers the three reads every write is preceded by: the objecttype list (matched by
    // name), that objecttype's versions, and the Objecten search for an existing record.
    private static HttpResponseMessage Route(HttpRequestMessage req, object[] existingObjects) =>
        req.RequestUri!.AbsolutePath.EndsWith("/versions", StringComparison.Ordinal)
            ? Json(new object[]
            {
                new { version = 1, status = "published" },
                new { version = 2, status = "published" },
                // A draft must never be written against, even though it is the highest version.
                new { version = 3, status = "draft" },
            })
            : req.RequestUri.AbsolutePath.StartsWith("/api/v2/objecttypes", StringComparison.Ordinal)
                ? Json(new
                {
                    results = new[]
                    {
                        new { url = "http://objecttypen:8000/api/v2/objecttypes/other", name = "SomethingElse" },
                        new { url = ObjecttypeUrl, name = "RegisterRecord" },
                    },
                })
                : req.Method == HttpMethod.Get
                    ? Json(new { results = existingObjects })
                    : new HttpResponseMessage(HttpStatusCode.Created) { Content = JsonContent.Create(new { url = "http://objecten:8000/api/v2/objects/obj-1" }) };

    private static HttpResponseMessage Json(object body) =>
        new(HttpStatusCode.OK) { Content = JsonContent.Create(body) };

    private static RegisterRecord Record() => new("zaak-uuid-1", RegisterRecordStatus.Ingeschreven, "REG-2026-0001");

    [Fact]
    public async Task Creates_the_object_when_none_exists_for_the_registration()
    {
        var sent = new List<Sent>();

        await Gateway(sent, req => Route(req, [])).UpsertAsync(Record());

        var write = sent.Single(s => s.Method == HttpMethod.Post && s.Uri.AbsolutePath == "/api/v2/objects");
        Assert.Contains($"\"type\":\"{ObjecttypeUrl}\"", write.Body);
        // The highest *published* version (2), not the highest version (a draft 3).
        Assert.Contains("\"typeVersion\":2", write.Body);
        Assert.Contains("\"id\":\"zaak-uuid-1\"", write.Body);
        Assert.Contains("\"status\":\"INGESCHREVEN\"", write.Body);
        Assert.Contains("\"reference\":\"REG-2026-0001\"", write.Body);
        Assert.Contains("\"startAt\":\"2026-06-04\"", write.Body);
    }

    [Fact]
    public async Task Updates_the_existing_object_instead_of_creating_a_second_one()
    {
        var sent = new List<Sent>();
        object[] existing = [new { uuid = "obj-9", url = "http://objecten:8000/api/v2/objects/obj-9" }];

        await Gateway(sent, req => Route(req, existing)).UpsertAsync(Record());

        Assert.DoesNotContain(sent, s => s.Method == HttpMethod.Post && s.Uri.AbsolutePath == "/api/v2/objects");
        var write = sent.Single(s => s.Method == HttpMethod.Patch);
        Assert.Equal("http://objecten:8000/api/v2/objects/obj-9", write.Uri.ToString());
        Assert.Contains("\"status\":\"INGESCHREVEN\"", write.Body);
    }

    [Fact]
    public async Task Searches_objecten_for_the_registration_id_within_the_objecttype()
    {
        var sent = new List<Sent>();

        await Gateway(sent, req => Route(req, [])).UpsertAsync(Record());

        var search = sent.Single(s => s.Method == HttpMethod.Get && s.Uri.AbsolutePath == "/api/v2/objects");
        Assert.Contains("type=" + Uri.EscapeDataString(ObjecttypeUrl), search.Uri.Query);
        Assert.Contains("data_attrs=id__exact__zaak-uuid-1", search.Uri.Query);
    }

    [Fact]
    public async Task Authenticates_with_the_static_token_of_each_api()
    {
        var sent = new List<Sent>();

        await Gateway(sent, req => Route(req, [])).UpsertAsync(Record());

        Assert.All(
            sent.Where(s => s.Uri.AbsolutePath.StartsWith("/api/v2/objecttypes", StringComparison.Ordinal)),
            s => Assert.Equal("Token objecttypen-token", s.Auth));
        Assert.All(
            sent.Where(s => s.Uri.AbsolutePath.StartsWith("/api/v2/objects", StringComparison.Ordinal)),
            s => Assert.Equal("Token objecten-token", s.Auth));
    }

    [Fact]
    public async Task Sends_the_geo_crs_headers_the_objecten_api_requires()
    {
        var sent = new List<Sent>();

        await Gateway(sent, req => Route(req, [])).UpsertAsync(Record());

        var objects = sent.Where(s => s.Uri.AbsolutePath.StartsWith("/api/v2/objects", StringComparison.Ordinal)).ToList();
        Assert.All(objects, s => Assert.Equal("EPSG:4326", s.AcceptCrs));
        Assert.All(objects.Where(s => s.Body is not null), s => Assert.Equal("EPSG:4326", s.ContentCrs));
    }

    [Fact]
    public async Task Resolves_the_objecttype_once_and_reuses_it_across_writes()
    {
        var sent = new List<Sent>();
        var gateway = Gateway(sent, req => Route(req, []));

        await gateway.UpsertAsync(Record());
        await gateway.UpsertAsync(Record() with { Id = "zaak-uuid-2" });

        Assert.Single(sent, s => s.Uri.AbsolutePath == "/api/v2/objecttypes");
    }

    [Fact]
    public async Task Fails_loudly_when_the_objecttype_has_no_published_version()
    {
        var sent = new List<Sent>();
        var gateway = Gateway(sent, req => req.RequestUri!.AbsolutePath.EndsWith("/versions", StringComparison.Ordinal)
            ? Json(new object[] { new { version = 1, status = "draft" } })
            : Route(req, []));

        var error = await Assert.ThrowsAsync<InvalidOperationException>(() => gateway.UpsertAsync(Record()));
        Assert.Contains("published version", error.Message);
    }

    [Fact]
    public async Task Fails_loudly_when_the_objecttype_is_not_registered()
    {
        var sent = new List<Sent>();
        var gateway = Gateway(sent, _ => new HttpResponseMessage(HttpStatusCode.OK)
        {
            Content = JsonContent.Create(new { results = Array.Empty<object>() }),
        });

        var error = await Assert.ThrowsAsync<InvalidOperationException>(() => gateway.UpsertAsync(Record()));
        Assert.Contains("RegisterRecord", error.Message);
    }

    [Fact]
    public async Task Surfaces_the_objecten_error_body_when_a_write_is_rejected()
    {
        var sent = new List<Sent>();
        var gateway = Gateway(sent, req => req.Method == HttpMethod.Post && req.RequestUri!.AbsolutePath == "/api/v2/objects"
            ? new HttpResponseMessage(HttpStatusCode.BadRequest) { Content = new StringContent("{\"detail\":\"schema mismatch\"}") }
            : Route(req, []));

        var error = await Assert.ThrowsAsync<HttpRequestException>(() => gateway.UpsertAsync(Record()));
        Assert.Contains("schema mismatch", error.Message);
        Assert.Contains("Creating the register record", error.Message);
    }

    [Fact]
    public async Task Surfaces_the_objecten_error_body_when_an_update_is_rejected()
    {
        var sent = new List<Sent>();
        object[] existing = [new { url = "http://objecten:8000/api/v2/objects/obj-9" }];
        var gateway = Gateway(sent, req => req.Method == HttpMethod.Patch
            ? new HttpResponseMessage(HttpStatusCode.BadRequest) { Content = new StringContent("{\"detail\":\"stale version\"}") }
            : Route(req, existing));

        var error = await Assert.ThrowsAsync<HttpRequestException>(() => gateway.UpsertAsync(Record()));
        Assert.Contains("stale version", error.Message);
        Assert.Contains("Updating the register record", error.Message);
    }

    [Fact]
    public async Task Surfaces_a_failed_read_instead_of_writing_blind()
    {
        var sent = new List<Sent>();
        var gateway = Gateway(sent, _ => new HttpResponseMessage(HttpStatusCode.Unauthorized)
        {
            Content = new StringContent("{\"detail\":\"invalid token\"}"),
        });

        var error = await Assert.ThrowsAsync<HttpRequestException>(() => gateway.UpsertAsync(Record()));
        Assert.Contains("Querying objecttypen", error.Message);
        Assert.Contains("invalid token", error.Message);
        // A read that failed must never be mistaken for "nothing there yet" and followed by a write.
        Assert.DoesNotContain(sent, s => s.Method == HttpMethod.Post || s.Method == HttpMethod.Patch);
    }

    [Fact]
    public async Task Surfaces_an_empty_read_body_rather_than_dereferencing_it()
    {
        var sent = new List<Sent>();
        var gateway = Gateway(sent, _ => new HttpResponseMessage(HttpStatusCode.OK)
        {
            Content = new StringContent("null", System.Text.Encoding.UTF8, "application/json"),
        });

        var error = await Assert.ThrowsAsync<InvalidOperationException>(() => gateway.UpsertAsync(Record()));
        Assert.Contains("objecttypen", error.Message);
    }

    [Fact]
    public async Task Treats_a_result_less_response_as_no_match_rather_than_crashing()
    {
        var sent = new List<Sent>();
        // Neither collection carries a `results` key — the objecttype is absent, which must surface as
        // the "not registered" error rather than a NullReferenceException.
        var gateway = Gateway(sent, req => req.RequestUri!.AbsolutePath.EndsWith("/versions", StringComparison.Ordinal)
            ? Json(Array.Empty<object>())
            : Json(new { }));

        await Assert.ThrowsAsync<InvalidOperationException>(() => gateway.UpsertAsync(Record()));
    }

    [Fact]
    public async Task Creates_the_object_when_the_search_response_carries_no_results_key()
    {
        var sent = new List<Sent>();
        var gateway = Gateway(sent, req => req.Method == HttpMethod.Get && req.RequestUri!.AbsolutePath == "/api/v2/objects"
            ? Json(new { })
            : Route(req, []));

        await gateway.UpsertAsync(Record());

        Assert.Contains(sent, s => s.Method == HttpMethod.Post && s.Uri.AbsolutePath == "/api/v2/objects");
    }

    [Fact]
    public async Task Reads_objecttypen_without_the_crs_headers_it_does_not_accept()
    {
        var sent = new List<Sent>();

        await Gateway(sent, req => Route(req, [])).UpsertAsync(Record());

        // Objecttypen is not a geo API; only the Objecten hops carry CRS.
        Assert.All(
            sent.Where(s => s.Uri.AbsolutePath.StartsWith("/api/v2/objecttypes", StringComparison.Ordinal)),
            s => Assert.Null(s.AcceptCrs));
    }

    [Fact]
    public async Task Buffers_the_write_body_so_uwsgi_gets_a_content_length()
    {
        var sent = new List<Sent>();

        await Gateway(sent, req => Route(req, [])).UpsertAsync(Record());

        var write = sent.Single(s => s.Method == HttpMethod.Post && s.Uri.AbsolutePath == "/api/v2/objects");
        Assert.NotNull(write.ContentLength);
    }

    [Fact]
    public async Task Rejects_a_null_record_without_calling_objecten()
    {
        var sent = new List<Sent>();

        await Assert.ThrowsAsync<ArgumentNullException>(() => Gateway(sent, req => Route(req, [])).UpsertAsync(null!));
        Assert.Empty(sent);
    }
}