using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect.Tests;

/// <summary>
///     <see cref="MTConnectDriver"/>'s <see cref="IWritable"/> leg — the batch contract, the per-slot
///     refusals, and the one thing the driver has to get right before the Agent is even dialled: which
///     device a DataItem belongs to.
/// </summary>
/// <remarks>
///     <para>
///         <b>The write itself is the live gate's job.</b> Everything below stops at the
///         <see cref="IMTConnectAgentClient"/> seam and asserts what the driver <i>asked</i> the Agent
///         for (<see cref="CannedAgentClient.Writes"/>), never that a fake was called for its own sake —
///         the same philosophy as <c>MqttDriverWriteTests</c>. What IS worth pinning offline is
///         everything that decides whether a write should reach an Agent at all, because that is where
///         a silent no-op would hide.
///     </para>
///     <para>
///         <b>A write is observation injection, not machine command</b> (design §2.2): it sets what the
///         Agent reports for a DataItem, and the next adapter update overwrites it. That is why the
///         feature is off at two independent gates — the Agent's <c>AllowPut</c>, and this driver's
///         <c>write.enabled</c> — and why the disabled leg below is the first test in the file.
///     </para>
/// </remarks>
public sealed class MTConnectWriteTests
{
    private const string AgentUri = "http://fixture-agent:5000";

    /// <summary>The device the canned <c>Fixtures/probe.xml</c> declares — <c>id="dev1" name="VMC-3Axis"</c>.</summary>
    private const string FixtureDeviceName = "VMC-3Axis";

    private const string PositionDataItemId = "dev1_pos";
    private const string ConditionDataItemId = "dev1_system_cond";

    private const string PositionRawPath = "Plant/MTConnect/dev1/Position";
    private const string ConditionRawPath = "Plant/MTConnect/dev1/SystemCondition";
    private const string UnknownRawPath = "Plant/MTConnect/dev1/NotATag";

    private const uint Good = 0x00000000u;
    private const uint BadNodeIdUnknown = 0x80340000u;
    private const uint BadNotWritable = 0x803B0000u;
    private const uint BadTypeMismatch = 0x80740000u;
    private const uint BadCommunicationError = 0x80050000u;
    private const uint BadNotConnected = 0x808A0000u;

    private static CancellationToken Ct => TestContext.Current.CancellationToken;

    /// <summary>One authored raw tag bound to a DataItem id, as the browse-commit flow writes it.</summary>
    private static RawTagEntry Entry(string rawPath, string dataItemId) =>
        new(rawPath, $$"""{"fullName":"{{dataItemId}}"}""", WriteIdempotent: false, DeviceName: "dev1");

    private static MTConnectDriverOptions Opts(
        bool writeEnabled = true, string? deviceName = null, params RawTagEntry[] rawTags) =>
        new()
        {
            AgentUri = AgentUri,
            DeviceName = deviceName,
            Tags = [],
            RawTags = rawTags,
            Write = new MTConnectWriteOptions { Enabled = writeEnabled },
        };

    private static (MTConnectDriver Driver, CannedAgentClient Client) NewDriver(
        MTConnectDriverOptions options, RecordingDriverLogger? logger = null)
    {
        var client = CannedAgentClient.FromFixtures();

        return (new MTConnectDriver(options, "mt1", _ => client, logger), client);
    }

    private static async Task<(MTConnectDriver Driver, CannedAgentClient Client)> InitializedAsync(
        MTConnectDriverOptions options, RecordingDriverLogger? logger = null)
    {
        var (driver, client) = NewDriver(options, logger);
        await driver.InitializeAsync("{}", Ct);

        return (driver, client);
    }

    /// <summary>The ordinary rig: write on, one writable position tag and the fixture's CONDITION item.</summary>
    private static Task<(MTConnectDriver Driver, CannedAgentClient Client)> WritableDriverAsync(
        RecordingDriverLogger? logger = null) =>
        InitializedAsync(
            Opts(
                writeEnabled: true,
                deviceName: null,
                Entry(PositionRawPath, PositionDataItemId),
                Entry(ConditionRawPath, ConditionDataItemId)),
            logger);

    // ---- the capability itself ----

    [Fact]
    public void MTConnectDriver_implements_IWritable()
        // The interface's presence IS the feature: without it the runtime's capability dispatch never
        // offers this driver a write, whatever a node advertises.
        => NewDriver(Opts()).Driver.ShouldBeAssignableTo<IWritable>();

    // ---- the two independent gates ----

    [Fact]
    public async Task A_driver_with_write_disabled_refuses_every_slot_without_dialling_the_agent()
    {
        // The default. An existing deployment that never authors the block keeps today's read-only
        // behaviour EXACTLY — including making no request an Agent could log or accept.
        var (driver, client) = await InitializedAsync(
            Opts(writeEnabled: false, deviceName: null, Entry(PositionRawPath, PositionDataItemId)));

        var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);

        results.Count.ShouldBe(1);
        results[0].StatusCode.ShouldBe(BadNotWritable);
        client.Writes.ShouldBeEmpty();
    }

    [Fact]
    public async Task A_write_before_initialize_reports_not_connected()
    {
        // Matches ReadAsync: "this driver is not running" is the only true statement available, and it
        // is NOT the same operator problem as an Agent that answered and refused.
        var (driver, _) = NewDriver(Opts(true, null, Entry(PositionRawPath, PositionDataItemId)));

        var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);

        results[0].StatusCode.ShouldBe(BadNotConnected);
    }

    [Fact]
    public async Task A_write_after_shutdown_reports_not_connected()
    {
        var (driver, _) = await WritableDriverAsync();
        await driver.ShutdownAsync(Ct);

        var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);

        results[0].StatusCode.ShouldBe(BadNotConnected);
    }

    // ---- per-slot refusals ----

    [Fact]
    public async Task An_unknown_reference_is_refused_in_its_own_slot()
    {
        var (driver, client) = await WritableDriverAsync();

        var results = await driver.WriteAsync([new WriteRequest(UnknownRawPath, 1.0)], Ct);

        results[0].StatusCode.ShouldBe(BadNodeIdUnknown);
        client.Writes.ShouldBeEmpty();
    }

    [Fact]
    public async Task A_condition_data_item_is_refused_as_not_writable()
    {
        // CONDITION PUTs carry alarm semantics and a different level|text wire format — excluded from
        // v1. BadNotWritable, not BadTypeMismatch: the value was never the problem.
        var (driver, client) = await WritableDriverAsync();

        var results = await driver.WriteAsync([new WriteRequest(ConditionRawPath, "NORMAL")], Ct);

        results[0].StatusCode.ShouldBe(BadNotWritable);
        client.Writes.ShouldBeEmpty();
    }

    [Fact]
    public async Task A_null_value_is_refused_as_a_type_mismatch()
    {
        // A write IS a URL query value; there is no null to send. Refusing beats writing the empty
        // string, which the Agent would accept as a real observation.
        var (driver, client) = await WritableDriverAsync();

        var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, null)], Ct);

        results[0].StatusCode.ShouldBe(BadTypeMismatch);
        client.Writes.ShouldBeEmpty();
    }

    [Fact]
    public async Task An_array_value_is_refused_as_a_type_mismatch()
    {
        // Convert.ToString would happily render "System.Double[]" and the Agent would happily store it:
        // a silent corruption visible only on read-back. Array/TIME_SERIES writes are out of scope.
        var (driver, client) = await WritableDriverAsync();

        var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, new[] { 1.0, 2.0 })], Ct);

        results[0].StatusCode.ShouldBe(BadTypeMismatch);
        client.Writes.ShouldBeEmpty();
    }

    [Fact]
    public async Task A_non_convertible_composite_value_is_refused_as_a_type_mismatch()
    {
        // Driver.MTConnect-006. The array guard's stated REASON is "Convert.ToString falls back to
        // object.ToString for a non-IConvertible value", and an array is only one shape carrying that
        // property. A List<T> from a non-SDK caller (or an Opc.Ua.ExtensionObject, or an XmlElement)
        // renders as its TYPE NAME, which the Agent stores under a Good status — the identical
        // invisible corruption the array guard exists to prevent, refused nowhere.
        var (driver, client) = await WritableDriverAsync();

        var results = await driver.WriteAsync(
            [new WriteRequest(PositionRawPath, new List<double> { 1.0, 2.0 })],
            Ct);

        results[0].StatusCode.ShouldBe(BadTypeMismatch);
        client.Writes.ShouldBeEmpty();
    }

    [Theory]
    [InlineData((byte)7, "7")]
    [InlineData('x', "x")]
    [InlineData("already text", "already text")]
    public async Task An_IConvertible_scalar_still_writes(object value, string expected)
    {
        // Falsification control for the guard above: the accepted set must be UNCHANGED. Every scalar
        // this driver can carry is IConvertible, so a refusal expressed as "not a primitive I
        // recognise" — rather than as the IConvertible property the remark relies on — would silently
        // start refusing real writes instead of composite ones.
        var (driver, client) = await WritableDriverAsync();

        var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, value)], Ct);

        results[0].StatusCode.ShouldBe(Good);
        client.Writes.ShouldHaveSingleItem().Value.ShouldBe(expected);
    }

    [Fact]
    public async Task A_DateTime_still_writes_as_its_invariant_string()
    {
        // DateTime is IConvertible but is neither a primitive nor a string — the shape most likely to
        // be swept up by a hand-rolled "is this a scalar?" guard.
        var (driver, client) = await WritableDriverAsync();

        var results = await driver.WriteAsync(
            [new WriteRequest(PositionRawPath, new DateTime(2026, 8, 10, 13, 45, 0, DateTimeKind.Utc))],
            Ct);

        results[0].StatusCode.ShouldBe(Good);
        client.Writes.ShouldHaveSingleItem().Value.ShouldBe("08/10/2026 13:45:00");
    }

    [Fact]
    public async Task A_value_whose_own_formatter_throws_costs_its_slot_and_nothing_more()
    {
        // Convert.ToString runs the value's OWN ToString — arbitrary code that may throw anything —
        // and it runs OUTSIDE WriteAsync's per-slot try. A narrow catch filter let every exception
        // other than Format/InvalidCast/Overflow escape WriteAsync and fail the WHOLE batch, breaking
        // the never-throws contract. The load-bearing half of this test is the second slot: the good
        // write still happens.
        var (driver, client) = await WritableDriverAsync();

        var results = await driver.WriteAsync(
            [
                new WriteRequest(PositionRawPath, new ThrowingFormatter()),
                new WriteRequest(PositionRawPath, 42.5),
            ],
            Ct);

        results.Count.ShouldBe(2);
        results[0].StatusCode.ShouldBe(BadTypeMismatch);
        results[1].StatusCode.ShouldBe(Good);
        client.Writes.ShouldHaveSingleItem().Value.ShouldBe("42.5");
    }

    /// <summary>A value whose <see cref="ToString"/> throws something no conversion filter would name.</summary>
    private sealed class ThrowingFormatter
    {
        public override string ToString() =>
            throw new InvalidOperationException("this formatter is broken");
    }

    // ---- what actually reaches the seam ----

    [Fact]
    public async Task An_accepted_write_reports_good_and_names_the_owning_device_and_data_item()
    {
        // The device NAME is resolved from the /probe model, not from config: the Agent's PUT surface
        // is addressed per device, and a multi-device Agent must be addressed correctly with no extra
        // authoring. The RawPath is translated to the DataItem id, exactly as the read path does.
        var (driver, client) = await WritableDriverAsync();

        var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);

        results[0].StatusCode.ShouldBe(Good);
        client.Writes.ShouldHaveSingleItem()
            .ShouldBe((FixtureDeviceName, PositionDataItemId, "42.5"));
    }

    [Fact]
    public async Task A_value_is_rendered_with_the_invariant_culture()
    {
        // A comma decimal separator would be accepted by the Agent and read back as a different number.
        var (driver, client) = await WritableDriverAsync();

        await driver.WriteAsync([new WriteRequest(PositionRawPath, 1234.5678d)], Ct);

        client.Writes.ShouldHaveSingleItem().Value.ShouldBe("1234.5678");
    }

    [Fact]
    public async Task A_boolean_is_rendered_as_its_invariant_true_false_string()
    {
        // Boolean.ToString is culture-independent, so the invariant rendering is "True"/"False" — NOT
        // "1"/"0". Documented because it is the value an MTConnect consumer will see verbatim.
        var (driver, client) = await WritableDriverAsync();

        await driver.WriteAsync([new WriteRequest(PositionRawPath, true)], Ct);

        client.Writes.ShouldHaveSingleItem().Value.ShouldBe("True");
    }

    // ---- device-name resolution ----

    [Fact]
    public async Task A_data_item_the_probe_does_not_declare_falls_back_to_the_configured_device()
    {
        // The dataItemId-keyed authoring surface (the driver CLI) and any tag whose DataItem the Agent
        // has since dropped: config is the only device name available, and it is a real one.
        var (driver, client) = await InitializedAsync(
            Opts(writeEnabled: true, deviceName: "ConfiguredDevice", Entry(PositionRawPath, "not_in_probe")));

        var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 7)], Ct);

        results[0].StatusCode.ShouldBe(Good);
        client.Writes.ShouldHaveSingleItem().ShouldBe(("ConfiguredDevice", "not_in_probe", "7"));
    }

    [Fact]
    public async Task A_data_item_with_no_resolvable_device_is_refused_as_an_unknown_node()
    {
        // Neither the probe model nor config names a device, so there is no URL to POST to. Refused
        // rather than guessed: a wrong device path is a 404 the operator reads as "the Agent is broken".
        var (driver, client) = await InitializedAsync(
            Opts(writeEnabled: true, deviceName: null, Entry(PositionRawPath, "not_in_probe")));

        var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 7)], Ct);

        results[0].StatusCode.ShouldBe(BadNodeIdUnknown);
        client.Writes.ShouldBeEmpty();
    }

    // ---- how the Agent's own answers map ----

    [Fact]
    public async Task An_agent_refusal_maps_to_a_communication_error_and_logs_the_agents_own_text()
    {
        var logger = new RecordingDriverLogger();
        var (driver, client) = await WritableDriverAsync(logger);
        client.WriteOutcome = new MTConnectWriteOutcome(Accepted: false, AgentError: "UNSUPPORTED: no such device");

        var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);

        results[0].StatusCode.ShouldBe(BadCommunicationError);
        logger.WarningsSnapshot().ShouldContain(w => w.Contains("UNSUPPORTED: no such device", StringComparison.Ordinal));
    }

    [Fact]
    public async Task An_agent_refusal_never_reaches_the_health_LastError()
    {
        // Type-only discipline: LastError carries an exception TYPE, never Agent-authored text, and a
        // refused write is not evidence the driver's read path is degraded either.
        var (driver, client) = await WritableDriverAsync();
        var before = driver.GetHealth();
        client.WriteOutcome = new MTConnectWriteOutcome(Accepted: false, AgentError: "UNSUPPORTED: no such device");

        await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);

        var after = driver.GetHealth();
        after.LastError.ShouldBe(before.LastError);
        after.State.ShouldBe(before.State);
    }

    [Fact]
    public async Task A_transport_failure_maps_to_a_communication_error_without_throwing()
    {
        var (driver, client) = await WritableDriverAsync();
        client.WriteFailure = new HttpRequestException("connection refused");

        var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);

        results[0].StatusCode.ShouldBe(BadCommunicationError);
    }

    // ---- batch contract ----

    [Fact]
    public async Task Cancellation_fills_the_remaining_slots_and_returns_the_batch()
    {
        // Never throws, even cancelled: the caller gets one status per request or the node-manager
        // cannot tell which writes were attempted.
        var (driver, client) = await WritableDriverAsync();
        using var cts = new CancellationTokenSource();
        await cts.CancelAsync();

        var results = await driver.WriteAsync(
            [new WriteRequest(PositionRawPath, 1.0), new WriteRequest(PositionRawPath, 2.0)], cts.Token);

        results.Count.ShouldBe(2);
        results.ShouldAllBe(r => r.StatusCode == BadCommunicationError);
        client.Writes.ShouldBeEmpty();
    }

    [Fact]
    public async Task Cancellation_mid_batch_leaves_the_slots_already_written_with_their_real_outcomes()
    {
        // The fill must start at the cancelled slot, not overwrite the batch. Slot 0 completed against
        // the Agent before the token was cancelled, and reporting it BadCommunicationError would tell
        // an operator a write failed that actually landed — the one thing worse than reporting a
        // failure. Cancellation is injected from inside slot 0's own Agent call, so the ordering is a
        // fact of the run rather than a timing hope. (It used to be injected from a value's ToString;
        // such a value is not IConvertible and is now refused before it is ever rendered — see
        // Driver.MTConnect-006 — so the injection point moved to the seam it is asserting around.)
        var (driver, client) = await WritableDriverAsync();
        using var cts = new CancellationTokenSource();
        client.AfterWrite = () => cts.Cancel();

        var results = await driver.WriteAsync(
            [
                new WriteRequest(PositionRawPath, 42.5),
                new WriteRequest(PositionRawPath, 7.5),
                new WriteRequest(PositionRawPath, 9.5),
            ],
            cts.Token);

        results.Count.ShouldBe(3);
        results[0].StatusCode.ShouldBe(Good);
        results[1].StatusCode.ShouldBe(BadCommunicationError);
        results[2].StatusCode.ShouldBe(BadCommunicationError);

        // Exactly the pre-cancellation slot reached the Agent.
        client.Writes.ShouldHaveSingleItem().Value.ShouldBe("42.5");
    }

    [Fact]
    public async Task One_bad_request_does_not_fail_the_others_in_the_batch()
    {
        // Mirrors ReadAsync: failing the whole call would let one stale reference reject every other
        // write in the same OPC UA request.
        var (driver, client) = await WritableDriverAsync();

        var results = await driver.WriteAsync(
            [
                new WriteRequest(UnknownRawPath, 1.0),
                new WriteRequest(ConditionRawPath, "NORMAL"),
                new WriteRequest(PositionRawPath, 42.5),
            ],
            Ct);

        // Order-preserving, one status per request, each naming its own distinct cause.
        results.Count.ShouldBe(3);
        results[0].StatusCode.ShouldBe(BadNodeIdUnknown);
        results[1].StatusCode.ShouldBe(BadNotWritable);
        results[2].StatusCode.ShouldBe(Good);
        client.Writes.ShouldHaveSingleItem().DataItemId.ShouldBe(PositionDataItemId);
    }

    [Fact]
    public async Task An_empty_batch_is_answered_with_an_empty_result()
        => (await NewDriver(Opts()).Driver.WriteAsync([], Ct)).ShouldBeEmpty();

    [Fact]
    public async Task WriteAsync_rejects_a_null_batch()
        => await Should.ThrowAsync<ArgumentNullException>(
            async () => await NewDriver(Opts()).Driver.WriteAsync(null!, Ct));
}