using System.Net;
using System.Text.Json.Nodes;
using Fleet.Server;
using MoShiro.Backend.Application;
using MoShiro.TestSupport;

namespace MoShiro.Backend.Tests;

public sealed class LinkTests : IClassFixture<BackendFixture>
{
    private readonly BackendFixture _backend;

    public LinkTests(BackendFixture backend)
    {
        _backend = backend;
    }

    private async Task<HttpResponseMessage> SetLinkAsync(string dialer, string agent, bool? enabled) =>
        await _backend.Admin.PutAsync($"/api/admin/links/{dialer}/{agent}", BackendFixture.Json(new JsonObject { ["enabled"] = enabled }));

    private async Task SetAutoLinkAsync(bool on)
    {
        using HttpResponseMessage response = await _backend.Admin.PatchAsync("/api/admin/settings", BackendFixture.Json(new JsonObject { ["fleet.auto_link"] = on }, "application/merge-patch+json"));
        response.EnsureSuccessStatusCode();
    }

    private async Task<JsonNode?> LinkAsync(string dialer, string agent) =>
        (await _backend.GetJsonAsync(_backend.Admin, "/api/admin/links"))["items"]!.AsArray().FirstOrDefault(i => i!["dialer_id"]!.GetValue<string>() == dialer && i["listener_id"]!.GetValue<string>() == agent);

    [Fact]
    public async Task ListeningAgents_AutomaticallyShareOneLine_DialedBySmallerId()
    {
        await using AgentSimulator first = await _backend.ConnectAgentAsync();
        await using AgentSimulator second = await _backend.ConnectAgentAsync();
        string[] ids = [.. new[] { first.NodeId.Value, second.NodeId.Value }.Order(StringComparer.Ordinal)];
        (string a, string b) = (ids[0], ids[1]); // a 拨 b
        AgentSimulator listener = a == first.NodeId.Value ? second : first;
        AgentSimulator dialer = a == first.NodeId.Value ? first : second;
        Assert.True((await LinkAsync(a, b))!["linked"]!.GetValue<bool>());
        Assert.Null(await LinkAsync(b, a)); // 反方向不再有一条线路
        Assert.Null(await LinkAsync(a, a));
        using HttpResponseMessage self = await SetLinkAsync(a, a, true);
        Assert.Equal(HttpStatusCode.UnprocessableEntity, self.StatusCode);
        await listener.WaitForTaskSetAsync(s => s.Peers.Any(p => p.NodeId.Value == a));
        await dialer.WaitForTaskSetAsync(s => s.Peers.All(p => p.NodeId.Value != b)); // 拨出的一方不放行对端拨进来

        // 手动让 b 拨 a：线路换方向，仍然只有一条
        using HttpResponseMessage swap = await SetLinkAsync(b, a, true);
        swap.EnsureSuccessStatusCode();
        Assert.Null(await LinkAsync(a, b));
        Assert.True((await LinkAsync(b, a))!["linked"]!.GetValue<bool>());
        await dialer.WaitForTaskSetAsync(s => s.Peers.Any(p => p.NodeId.Value == b));

        // 关掉这一对：两个方向都不连，线路按默认方向显示，手动设置对这一对生效
        using HttpResponseMessage off = await SetLinkAsync(b, a, false);
        off.EnsureSuccessStatusCode();
        Assert.Null(await LinkAsync(b, a));
        JsonNode closed = (await LinkAsync(a, b))!;
        Assert.False(closed["linked"]!.GetValue<bool>());
        Assert.False(closed["override"]!.GetValue<bool>());
        await SetLinkAsync(b, a, null);
        Assert.True((await LinkAsync(a, b))!["linked"]!.GetValue<bool>());
    }

    private static AgentRecord Node(string id, bool listens) =>
        new(new Fleet.Core.NodeId(id), id, NodeStatus.Active, [], [], "", 0, [], [], true, [], null, null, 0, 0, null, 0, null, 0, Listens: listens);

    [Fact]
    public void DefaultDialer_NonListeningDials_ThenDomesticDialsForeign_ThenSmallerId()
    {
        AgentRecord home = Node("agt_a", listens: false);
        AgentRecord cn = Node("agt_b", listens: true);
        AgentRecord abroad = Node("agt_c", listens: true);
        AgentRecord abroad2 = Node("agt_d", listens: true);
        var snapshot = new LinkSnapshot(true, [], ["agt_b"]);

        Assert.True(snapshot.IsLinked(home, cn));            // 不监听的拨监听的
        Assert.False(snapshot.IsLinked(cn, home));
        Assert.True(snapshot.IsLinked(cn, abroad));          // 国内的拨国外的，哪怕它的 id 更小
        Assert.False(snapshot.IsLinked(abroad, cn));
        Assert.True(snapshot.IsLinked(abroad, abroad2));     // 一样的按 id，小的拨
        Assert.False(snapshot.IsLinked(abroad2, abroad));
        Assert.True(snapshot.IsLinked(home, cn));            // 只有国内的在监听时，国内的也得当监听方

        // 手动指定的方向不受国家影响：让国外的拨国内的
        var manual = new LinkSnapshot(true, new() { [("agt_c", "agt_b")] = true }, ["agt_b"]);
        Assert.True(manual.IsLinked(abroad, cn));
        Assert.False(manual.IsLinked(cn, abroad));
    }

    [Fact]
    public async Task Links_ResetDropsManualSettingsAndTurnsAutomaticLinkingOn()
    {
        await using AgentSimulator first = await _backend.ConnectAgentAsync();
        await using AgentSimulator second = await _backend.ConnectAgentAsync();
        string[] ids = [.. new[] { first.NodeId.Value, second.NodeId.Value }.Order(StringComparer.Ordinal)];
        await SetLinkAsync(ids[1], ids[0], true); // 手动让大 id 的拨小 id 的
        await SetAutoLinkAsync(false);
        try
        {
            using HttpResponseMessage reset = await _backend.Admin.PostAsync("/api/admin/links/reset", BackendFixture.Json(new JsonObject()));
            reset.EnsureSuccessStatusCode();
            JsonNode matrix = JsonNode.Parse(await reset.Content.ReadAsStringAsync())!;
            Assert.True(matrix["auto_link"]!.GetValue<bool>());
            JsonNode link = (await LinkAsync(ids[0], ids[1]))!; // 回到默认方向：小 id 拨大 id
            Assert.True(link["linked"]!.GetValue<bool>());
            Assert.Null(link["override"]);
        }
        finally
        {
            await SetAutoLinkAsync(true);
        }
    }

    [Fact]
    public async Task Links_FollowTheAutomaticSwitch_AndManualChoicesAlwaysWin()
    {
        await using AgentSimulator agent = await _backend.ConnectAgentAsync();
        string dialer = await _backend.CreateDialerIdAsync();
        string agentId = agent.NodeId.Value;
        try
        {
            // 自动连接（默认开）：新 Dialer 自动进入这个 Agent 允许的名单
            await agent.WaitForTaskSetAsync(s => s.Peers.Any(p => p.NodeId.Value == dialer));
            JsonNode link = (await LinkAsync(dialer, agentId))!;
            Assert.True(link["linked"]!.GetValue<bool>());
            Assert.Null(link["override"]);

            // 手动关掉这一对：自动连接开着也不连
            using HttpResponseMessage off = await SetLinkAsync(dialer, agentId, false);
            Assert.Equal(HttpStatusCode.OK, off.StatusCode);
            await agent.WaitForTaskSetAsync(s => s.Peers.All(p => p.NodeId.Value != dialer));
            Assert.False((await LinkAsync(dialer, agentId))!["linked"]!.GetValue<bool>());

            // 取消手动设置：回到自动连接
            using HttpResponseMessage reset = await SetLinkAsync(dialer, agentId, null);
            Assert.Equal(HttpStatusCode.OK, reset.StatusCode);
            await agent.WaitForTaskSetAsync(s => s.Peers.Any(p => p.NodeId.Value == dialer));

            // 关掉自动连接：没有手动选中的就都不连
            await SetAutoLinkAsync(false);
            await agent.WaitForTaskSetAsync(s => s.Peers.All(p => p.NodeId.Value != dialer));
            Assert.False((await _backend.GetJsonAsync(_backend.Admin, "/api/admin/links"))["auto_link"]!.GetValue<bool>());

            // 自动连接关着，手动选中的照样连
            await SetLinkAsync(dialer, agentId, true);
            await agent.WaitForTaskSetAsync(s => s.Peers.Any(p => p.NodeId.Value == dialer));
            Assert.True((await LinkAsync(dialer, agentId))!["override"]!.GetValue<bool>());
        }
        finally
        {
            await SetLinkAsync(dialer, agentId, null);
            await SetAutoLinkAsync(true); // 共用的后端：恢复默认，别影响别的测试
        }
    }

    [Fact]
    public async Task Links_RefuseUnknownNodes()
    {
        await using AgentSimulator agent = await _backend.ConnectAgentAsync();
        string dialer = await _backend.CreateDialerIdAsync();
        using HttpResponseMessage noDialer = await SetLinkAsync("agt_missing", agent.NodeId.Value, false);
        Assert.Equal(HttpStatusCode.NotFound, noDialer.StatusCode);
        using HttpResponseMessage noAgent = await SetLinkAsync(dialer, "agt_missing", false);
        Assert.Equal(HttpStatusCode.NotFound, noAgent.StatusCode);
    }

    [Fact]
    public async Task Links_RetryEnablesPairAndReportsWhenDialerIsOffline()
    {
        await using AgentSimulator agent = await _backend.ConnectAgentAsync();
        string dialer = await _backend.CreateDialerIdAsync();

        using HttpResponseMessage response = await _backend.Admin.PostAsync($"/api/admin/links/{dialer}/{agent.NodeId.Value}/retry", BackendFixture.Json(new JsonObject()));
        Assert.Equal(HttpStatusCode.Accepted, response.StatusCode);
        JsonNode body = JsonNode.Parse(await response.Content.ReadAsStringAsync())!;
        Assert.False(body["queued"]!.GetValue<bool>());
        Assert.True(body["link"]!["linked"]!.GetValue<bool>());
        Assert.Equal("dialer_unavailable", body["link"]!["connection_state"]!.GetValue<string>());
        Assert.Contains("拨号节点状态", body["link"]!["connection_reason"]!.GetValue<string>());
    }
}