using System.Net;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting.Server;
using Microsoft.AspNetCore.Hosting.Server.Features;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using WebDrop.Core;
using WebDrop.FileApi;
using WebDrop.Storage;
using static WebDrop.Api.Tests.ServerFixture;

namespace WebDrop.Api.Tests;

/// <summary>主后端 + 文件服务两个独立的服务一起跑:文件内容只在文件服务上;上传、登记、下载、计次、删除的完整流程。</summary>
public sealed class FileApiTests : IAsyncLifetime
{
    private const string Secret = "files-test-secret-0123456789abcdef-xyz";
    private readonly string _dir = Path.Combine(Path.GetTempPath(), "webdrop-files-" + Guid.NewGuid().ToString("N"));
    private WebApplication _files = null!;
    private ServerFixture _main = null!;
    private HttpClient _fileHttp = null!;
    private string _fileUrl = "";
    private Signer _owner = null!;

    private sealed record Signer(string Token, string Username, string DeviceId, byte[] PrivateKey);

    public async Task InitializeAsync()
    {
        _files = FileApiApp.Build([], b =>
        {
            b.Configuration["FileApi:DataDir"] = _dir;
            b.Configuration["FileApi:Secret"] = Secret;
            b.Configuration["urls"] = "http://127.0.0.1:0";
            b.Logging.ClearProviders();
        });
        await _files.StartAsync();
        _fileUrl = _files.Services.GetRequiredService<IServer>().Features.Get<IServerAddressesFeature>()!.Addresses.First().TrimEnd('/');
        _fileHttp = new HttpClient { BaseAddress = new Uri(_fileUrl) };

        _main = ServerFixture.WithSettings(new()
        {
            ["WebDrop:Files:Enabled"] = "true",
            ["WebDrop:Files:PublicUrl"] = _fileUrl,
            ["WebDrop:Files:InternalUrl"] = _fileUrl,
            ["WebDrop:Files:Secret"] = Secret,
        });
        await _main.InitializeAsync();
        _owner = await RegisterSignerAsync("files_owner");
    }

    public async Task DisposeAsync()
    {
        await _main.DisposeAsync();
        _fileHttp.Dispose();
        await _files.StopAsync();
        await _files.DisposeAsync();
        try { Directory.Delete(_dir, recursive: true); } catch (IOException) { }
    }

    // ───── 账号与签名:带设备签名密钥的账号,文件和聊天对象的最后一帧必须带签名事件 ─────

    private async Task<Signer> RegisterSignerAsync(string username)
    {
        var accounts = _main.App.Services.GetRequiredService<SqliteAccountStore>();
        var verifier = RandomNumberGenerator.GetBytes(32);
        using var invitation = ECDiffieHellman.Create(ECCurve.NamedCurves.nistP256);
        using var root = ECDsa.Create(ECCurve.NamedCurves.nistP256);
        using var device = ECDsa.Create(ECCurve.NamedCurves.nistP256);
        static string Jwk(ECPoint p) => JsonSerializer.Serialize(new { kty = "EC", crv = "P-256", x = B64(p.X!), y = B64(p.Y!) });
        var devicePoint = device.ExportParameters(false).Q;
        Assert.True(accounts.Register(username, RandomNumberGenerator.GetBytes(16), verifier, new byte[28], Jwk(invitation.ExportParameters(false).Q), Jwk(root.ExportParameters(false).Q)));
        string deviceId = Guid.NewGuid().ToString("D");
        var token = accounts.Authenticate(username, verifier, deviceId, "Test device")!;
        var cert = root.SignData(SignatureCodec.BuildMessage("device.certificate", SignatureCodec.DeviceCertificatePayload(username, deviceId, devicePoint.X!, devicePoint.Y!)),
            HashAlgorithmName.SHA256, DSASignatureFormat.IeeeP1363FixedFieldConcatenation);
        using var request = new HttpRequestMessage(HttpMethod.Put, "/api/v1/accounts/devices/signing-key")
        { Content = JsonBody(new { device_id = deviceId, public_key = Jwk(devicePoint), signature = Convert.ToBase64String(cert) }) };
        request.Headers.Add("X-WD-Account", token);
        Assert.Equal(HttpStatusCode.NoContent, (await _main.Http.SendAsync(request)).StatusCode);
        return new Signer(token, username, deviceId, device.ExportPkcs8PrivateKey());
    }

    /// <summary>条目最后一帧的签名事件头:对所有帧的摘要(清单)签名</summary>
    private Dictionary<string, string> SignedHeaders(string spaceId, string channelId, string itemId, CryptoDomain domain, string kind, IReadOnlyList<byte[]> frames)
    {
        Assert.True(Codec.TryDecodeExact(spaceId, 16, out var space)); Assert.True(Codec.TryDecodeExact(itemId, 16, out var item));
        var manifest = SignatureCodec.FrameManifestHash(frames.Select(frame => SHA256.HashData(frame)).ToList());
        var eventId = RandomNumberGenerator.GetBytes(16);
        var payload = SignatureCodec.ContentEventPayload(space, channelId, _owner.Username, _owner.DeviceId, eventId, kind, domain, 1, item, frames.Count, manifest, []);
        using var device = ECDsa.Create(); device.ImportPkcs8PrivateKey(_owner.PrivateKey, out _);
        var signature = device.SignData(SignatureCodec.BuildMessage("content.event", payload), HashAlgorithmName.SHA256, DSASignatureFormat.IeeeP1363FixedFieldConcatenation);
        return new Dictionary<string, string>
        {
            ["X-WD-Event-Id"] = B64(eventId), ["X-WD-Event-Kind"] = kind, ["X-WD-Event-Channel"] = channelId,
            ["X-WD-Event-Domain"] = domain == CryptoDomain.Chat ? "chat" : "files", ["X-WD-Event-Epoch"] = "1", ["X-WD-Event-Frames"] = frames.Count.ToString(),
            ["X-WD-Event-Manifest"] = B64(manifest), ["X-WD-Event-Signature"] = B64(signature),
        };
    }

    private Who Owner(Chan ch) => ch.Owner with { AccountToken = _owner.Token };

    private async Task<Chan> CreateSpaceAsync()
    {
        var ch = new Chan(NewId(), ChannelMode.Enc);
        var body = new Dictionary<string, object?>
        {
            ["id"] = ch.Id, ["mode"] = "enc", ["owner_hash"] = B64(TokenHash.Compute(ch.OwnerToken)),
            ["write_hash"] = B64(TokenHash.Compute(ch.WriteToken)), ["read_hash"] = B64(TokenHash.Compute(ch.ReadToken)),
            ["settings"] = new { name = "Files space", max_members = 2, join_policy = "open" },
        };
        using var response = await _main.Http.SendAsync(_main.Req(HttpMethod.Post, "/api/v1/channels", Owner(ch), JsonBody(body)));
        Assert.Equal(HttpStatusCode.Created, response.StatusCode);
        return ch;
    }

    /// <summary>空间里的默认频道:发布聊天和文件两个域的密钥(客户端创建空间时做的事),之后才能声明对象</summary>
    private async Task<string> PrepareAsync(Chan ch)
    {
        string channelId;
        using (var request = _main.Req(HttpMethod.Get, $"/api/v1/spaces/{ch.Id}/structure", Owner(ch)))
        using (var response = await _main.Http.SendAsync(request))
            channelId = (await ReadJsonAsync(response)).GetProperty("structure").GetProperty("defaultChannelId").GetString()!;
        foreach (var domain in new[] { "chat", "files" })
        {
            using var bootstrap = _main.Req(HttpMethod.Put, $"/api/v1/spaces/{ch.Id}/crypto/domains", Owner(ch),
                JsonBody(new { channelId, domain, epoch = 1, envelopes = new[] { new { channelId, domain, epoch = 1, username = _owner.Username, payload = $"owner-{domain}" } } }));
            Assert.Equal(HttpStatusCode.NoContent, (await _main.Http.SendAsync(bootstrap)).StatusCode);
        }
        return channelId;
    }

    private async Task DeclareAsync(Chan ch, string channelId, string itemId, string domain = "files")
    {
        using var declare = _main.Req(HttpMethod.Post, $"/api/v1/spaces/{ch.Id}/crypto/objects", Owner(ch),
            JsonBody(new { itemId, channelId, domain, epoch = 1, keyEnvelope = "opaque-object-key" }));
        Assert.Equal(HttpStatusCode.Created, (await _main.Http.SendAsync(declare)).StatusCode);
    }

    // ───── 文件服务和主后端的请求 ─────

    private async Task<HttpResponseMessage> TicketRequestAsync(Chan ch, string item, string op, uint from = 0) =>
        await _main.Http.SendAsync(_main.Req(HttpMethod.Post, $"/api/v1/channels/{ch.Id}/files/ticket", Owner(ch),
            new StringContent(JsonSerializer.Serialize(new { item, op, from }), Encoding.UTF8, "application/json")));

    private async Task<(string Mode, string? Url, string? Ticket)> TicketAsync(Chan ch, string item, string op, uint from = 0)
    {
        using var response = await TicketRequestAsync(ch, item, op, from);
        if (response.StatusCode != HttpStatusCode.OK) throw new HttpRequestException($"ticket {(int)response.StatusCode} {await response.Content.ReadAsStringAsync()}");
        using var doc = JsonDocument.Parse(await response.Content.ReadAsStringAsync());
        var root = doc.RootElement;
        return (root.GetProperty("mode").GetString()!, root.TryGetProperty("url", out var u) ? u.GetString() : null, root.TryGetProperty("ticket", out var t) ? t.GetString() : null);
    }

    private async Task<string> StoreAsync(Chan ch, string item, byte[] frame, uint index)
    {
        var (_, _, ticket) = await TicketAsync(ch, item, "put");
        using var put = new HttpRequestMessage(HttpMethod.Put, $"/f/{Hex(ch.Id)}/{Hex(item)}/{index}") { Content = new ByteArrayContent(frame) };
        put.Headers.Add("X-WD-Ticket", ticket);
        using var stored = await _fileHttp.SendAsync(put);
        Assert.Equal(HttpStatusCode.OK, stored.StatusCode);
        using var doc = JsonDocument.Parse(await stored.Content.ReadAsStringAsync());
        return doc.RootElement.GetProperty("receipt").GetString()!;
    }

    private async Task<HttpResponseMessage> CommitAsync(Chan ch, byte[] frame, string receipt, string? maxDownloads = null, Dictionary<string, string>? signed = null)
    {
        var commit = _main.Req(HttpMethod.Post, $"/api/v1/channels/{ch.Id}/frames", Owner(ch), new ByteArrayContent(frame[..26]));
        commit.Headers.Add("X-WD-Receipt", receipt);
        if (maxDownloads is not null) commit.Headers.Add("X-WD-Max-Downloads", maxDownloads);
        foreach (var (name, value) in signed ?? []) commit.Headers.Add(name, value);
        return await _main.Http.SendAsync(commit);
    }

    /// <summary>上传一个文件条目的帧:每帧先传给文件服务拿回执,再把头部和回执交给主后端登记;最后一帧带签名事件</summary>
    private async Task<List<HttpStatusCode>> UploadFileAsync(Chan ch, string channelId, string item, IReadOnlyList<byte[]> frames, string? maxDownloads = null, bool final = true)
    {
        var statuses = new List<HttpStatusCode>();
        for (int i = 0; i < frames.Count; i++)
        {
            string receipt = await StoreAsync(ch, item, frames[i], (uint)i);
            var signed = final && i == frames.Count - 1 ? SignedHeaders(ch.Id, channelId, item, CryptoDomain.Files, "file.publish", frames) : null;
            using var response = await CommitAsync(ch, frames[i], receipt, i == 0 ? maxDownloads : null, signed);
            statuses.Add(response.StatusCode);
        }
        return statuses;
    }

    private async Task<(HttpResponseMessage Response, byte[] Body)> ReadFromFilesAsync(Chan ch, string item, string ticket, uint from)
    {
        using var get = new HttpRequestMessage(HttpMethod.Get, $"/f/{Hex(ch.Id)}/{Hex(item)}?from={from}");
        get.Headers.Add("X-WD-Ticket", ticket);
        var response = await _fileHttp.SendAsync(get);
        return (response, await response.Content.ReadAsByteArrayAsync());
    }

    private static byte[] Small(string item, byte fill = 0x42) => Frame(item, 0, FinalEnc, EncPayload, fill);

    private static string Hex(string base64UrlId)
    {
        Assert.True(Codec.TryDecodeExact(base64UrlId, 16, out var bytes));
        return Convert.ToHexStringLower(bytes);
    }

    // ───── 测试 ─────

    [Fact]
    public async Task FileContentOfAnySizeGoesToTheFileServiceWhileChatStaysOnTheMainBackend()
    {
        Assert.Contains("\"files\":{\"enabled\":true", await _main.Http.GetStringAsync("/api/v1/info"));

        var ch = await CreateSpaceAsync();
        string channelId = await PrepareAsync(ch);
        string item = NewId(), tiny = NewId(), chat = NewId();
        await DeclareAsync(ch, channelId, item); await DeclareAsync(ch, channelId, tiny); await DeclareAsync(ch, channelId, chat, "chat");
        var frames = new[] { Frame(item, 0, GatedEnc, EncPayload, 1), Frame(item, 1, GatedEnc, EncPayload, 2), Frame(item, 2, GatedFinalEnc, EncPayload, 3) };
        var tinyFrame = Small(tiny, 7);   // 单帧、不限次的小文件,同样放文件服务

        // 文件的内容不能直接传给主后端,不管是多帧受限的还是单帧的小文件
        using (var direct = await _main.AppendAsync(ch, Owner(ch), frames[0], maxDownloads: "1")) Assert.Equal(HttpStatusCode.Conflict, direct.StatusCode);
        using (var directSmall = _main.Req(HttpMethod.Post, $"/api/v1/channels/{ch.Id}/frames", Owner(ch), Bytes(tinyFrame)))
        {
            foreach (var (name, value) in SignedHeaders(ch.Id, channelId, tiny, CryptoDomain.Files, "file.publish", [tinyFrame])) directSmall.Headers.Add(name, value);
            using var rejected = await _main.Http.SendAsync(directSmall);
            Assert.Equal(HttpStatusCode.Conflict, rejected.StatusCode);
        }

        Assert.All(await UploadFileAsync(ch, channelId, item, frames, "1"), s => Assert.Equal(HttpStatusCode.Created, s));
        Assert.All(await UploadFileAsync(ch, channelId, tiny, [tinyFrame]), s => Assert.Equal(HttpStatusCode.Created, s));

        // 聊天(聊天域的对象)照旧存在主后端,日志里带着内容
        var chatFrame = Small(chat, 5);
        using (var chatRequest = _main.Req(HttpMethod.Post, $"/api/v1/channels/{ch.Id}/frames", Owner(ch), Bytes(chatFrame)))
        {
            foreach (var (name, value) in SignedHeaders(ch.Id, channelId, chat, CryptoDomain.Chat, "chat.create", [chatFrame])) chatRequest.Headers.Add(name, value);
            using var chatResponse = await _main.Http.SendAsync(chatRequest);
            Assert.Equal(HttpStatusCode.Created, chatResponse.StatusCode);
        }
        var (_, logBody) = await _main.GetBytesAsync($"/api/v1/channels/{ch.Id}/log", Owner(ch));
        var log = ParseLog(logBody);
        Assert.Equal(2, log.Count(r => r.Kind == LogKind.Announce));       // 两个文件条目都只是「公布」
        Assert.Equal(1, log.Count(r => r.Kind == LogKind.Frame));          // 只有聊天帧带内容
        await AssertErrorAsync(await _main.Http.SendAsync(_main.Req(HttpMethod.Get, $"/api/v1/channels/{ch.Id}/items/{item}/frames", Owner(ch))), 409, "use_file_api");

        // 受限条目:要票据,按原来的规则计次(上限 1 次)
        var grant = await TicketAsync(ch, item, "get");
        Assert.Equal("remote", grant.Mode);
        var (read, body) = await ReadFromFilesAsync(ch, item, grant.Ticket!, 0);
        Assert.Equal(HttpStatusCode.OK, read.StatusCode);
        Assert.Equal(frames.SelectMany(f => f).ToArray(), body);
        using (var second = await TicketRequestAsync(ch, item, "get")) Assert.Equal(HttpStatusCode.Gone, second.StatusCode);
        var resume = await TicketAsync(ch, item, "get", 2);
        Assert.Equal(frames[2], (await ReadFromFilesAsync(ch, item, resume.Ticket!, 2)).Body);

        // 单帧小文件不受限:想读几次都行
        for (int i = 0; i < 3; i++)
        {
            var t = await TicketAsync(ch, tiny, "get");
            Assert.Equal("remote", t.Mode);
            Assert.Equal(tinyFrame, (await ReadFromFilesAsync(ch, tiny, t.Ticket!, 0)).Body);
        }

        // 聊天条目请求下载票据得到 local:客户端继续走原来的接口
        Assert.Equal("local", (await TicketAsync(ch, chat, "get")).Mode);
    }

    [Fact]
    public async Task TicketsAndReceiptsAreBoundToTheirItemAndFrame()
    {
        var ch = await CreateSpaceAsync();
        string channelId = await PrepareAsync(ch);
        string item = NewId(), other = NewId();
        await DeclareAsync(ch, channelId, item);
        var f0 = Frame(item, 0, GatedEnc, EncPayload, 1);
        var f1 = Frame(item, 1, GatedFinalEnc, EncPayload, 2);

        // 别的条目的票据传不进这个条目;没有票据也不行
        var (_, _, otherTicket) = await TicketAsync(ch, other, "put");
        using (var put = new HttpRequestMessage(HttpMethod.Put, $"/f/{Hex(ch.Id)}/{Hex(item)}/0") { Content = new ByteArrayContent(f0) })
        {
            put.Headers.Add("X-WD-Ticket", otherTicket);
            using var denied = await _fileHttp.SendAsync(put);
            Assert.Equal(HttpStatusCode.Unauthorized, denied.StatusCode);
        }
        using (var noTicket = await _fileHttp.PutAsync($"/f/{Hex(ch.Id)}/{Hex(item)}/0", new ByteArrayContent(f0))) Assert.Equal(HttpStatusCode.Unauthorized, noTicket.StatusCode);

        // 回执被篡改、或拿第 0 帧的回执去登记第 1 帧,都会被拒绝
        string receipt0 = await StoreAsync(ch, item, f0, 0);
        using (var forged = await CommitAsync(ch, f0, "x.y", "1")) Assert.Equal(HttpStatusCode.Forbidden, forged.StatusCode);
        using (var committed0 = await CommitAsync(ch, f0, receipt0, "1")) Assert.Equal(HttpStatusCode.Created, committed0.StatusCode);
        await StoreAsync(ch, item, f1, 1);
        using (var swapped = await CommitAsync(ch, f1, receipt0, null, SignedHeaders(ch.Id, channelId, item, CryptoDomain.Files, "file.publish", [f0, f1])))
            Assert.Equal(HttpStatusCode.Forbidden, swapped.StatusCode);

        // 同一个序号不能存不同的内容;同样的内容重传是幂等的
        var (_, _, ticketAgain) = await TicketAsync(ch, item, "put");
        using (var put = new HttpRequestMessage(HttpMethod.Put, $"/f/{Hex(ch.Id)}/{Hex(item)}/0") { Content = new ByteArrayContent(Frame(item, 0, GatedEnc, EncPayload, 9)) })
        {
            put.Headers.Add("X-WD-Ticket", ticketAgain);
            using var conflict = await _fileHttp.SendAsync(put);
            Assert.Equal(HttpStatusCode.Conflict, conflict.StatusCode);
        }
        using (var again = await CommitAsync(ch, f0, await StoreAsync(ch, item, f0, 0), "1")) Assert.True(again.IsSuccessStatusCode);

        // 没传完的条目不能下载;不是文件的条目不能走文件服务登记
        using (var notReady = await TicketRequestAsync(ch, item, "get")) Assert.Equal(HttpStatusCode.Conflict, notReady.StatusCode);
        string chat = NewId();
        await DeclareAsync(ch, channelId, chat, "chat");
        var chatFrame = Small(chat);
        string chatReceipt = await StoreAsync(ch, chat, chatFrame, 0);
        using (var notAFile = await CommitAsync(ch, chatFrame, chatReceipt, null, SignedHeaders(ch.Id, channelId, chat, CryptoDomain.Chat, "chat.create", [chatFrame])))
            Assert.Equal(HttpStatusCode.BadRequest, notAFile.StatusCode);
    }

    [Fact]
    public async Task DeletingAnItemOrChannelAlsoClearsTheFileService()
    {
        var ch = await CreateSpaceAsync();
        string channelId = await PrepareAsync(ch);
        var store = _files.Services.GetRequiredService<FrameStore>();

        // 没传完的条目可以直接删(取消上传):文件服务上的帧跟着清掉
        string unfinished = NewId();
        await DeclareAsync(ch, channelId, unfinished);
        Assert.All(await UploadFileAsync(ch, channelId, unfinished, [Frame(unfinished, 0, GatedEnc, EncPayload, 1)], "0", final: false), s => Assert.Equal(HttpStatusCode.Created, s));
        Assert.True(store.UsedBytes > 0);
        using (var delete = await _main.Http.SendAsync(_main.Req(HttpMethod.Delete, $"/api/v1/channels/{ch.Id}/items/{unfinished}", Owner(ch)))) Assert.Equal(HttpStatusCode.NoContent, delete.StatusCode);
        await WaitAsync(() => store.UsedBytes == 0);

        // 删除整个空间:里面所有文件一起清掉
        string finished = NewId();
        await DeclareAsync(ch, channelId, finished);
        Assert.All(await UploadFileAsync(ch, channelId, finished, [Small(finished, 3)]), s => Assert.Equal(HttpStatusCode.Created, s));
        Assert.True(store.UsedBytes > 0);
        using (var del = await _main.Http.SendAsync(_main.Req(HttpMethod.Delete, $"/api/v1/channels/{ch.Id}", Owner(ch)))) Assert.Equal(HttpStatusCode.NoContent, del.StatusCode);
        await WaitAsync(() => store.UsedBytes == 0);
    }

    [Fact]
    public async Task OrphansLeftByAbandonedUploadsAreFoundByReconciliation()
    {
        var ch = await CreateSpaceAsync();
        string item = NewId();
        // 只传给文件服务、从没在主后端登记过(上传到一半放弃)
        var (_, _, ticket) = await TicketAsync(ch, item, "put");
        using (var put = new HttpRequestMessage(HttpMethod.Put, $"/f/{Hex(ch.Id)}/{Hex(item)}/0") { Content = new ByteArrayContent(Frame(item, 0, GatedEnc, EncPayload, 1)) })
        {
            put.Headers.Add("X-WD-Ticket", ticket);
            using var stored = await _fileHttp.SendAsync(put);
            Assert.Equal(HttpStatusCode.OK, stored.StatusCode);
        }
        var store = _files.Services.GetRequiredService<FrameStore>();
        Assert.Contains($"{Hex(ch.Id)}/{Hex(item)}", store.ItemsOlderThan(TimeSpan.Zero));

        var worker = _main.App.Services.GetServices<Microsoft.Extensions.Hosting.IHostedService>().OfType<WebDrop.Api.FileReconcileWorker>().Single();
        var gateway = (WebDrop.Api.RemoteFileGateway)_main.App.Services.GetRequiredService<IFileGateway>();
        Assert.True(await worker.ReconcileAsync(gateway, CancellationToken.None, TimeSpan.Zero) >= 1);
        await WaitAsync(() => store.UsedBytes == 0);
    }

    private static async Task WaitAsync(Func<bool> condition)
    {
        for (int i = 0; i < 100 && !condition(); i++) await Task.Delay(100);
        Assert.True(condition());
    }
}