using SimpleCore;
using StandardScene.Magnetic.Protocol;
using StandardScene.Magnetic.Tasking;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Xunit;

namespace StandardScene.Magnetic.Tests.Tasking
{
    public class Fass2TaskStateMachineMustFixTests
    {
        [Fact]
        public async Task WaitForCompletion_AfterBootstrapFault_Throws_AndBeginIsAllowed()
        {
            var machine = CreateMachine();
            machine.Begin(10, 12);
            var tick = machine.Tick(Report(1, moving: true, startStop: 1, state: 4));

            Assert.True(tick.Faulted);
            Assert.Equal(Fass2TaskPhase.Fault, machine.Context.Phase);
            Assert.True(machine.IsIdle);

            await Assert.ThrowsAsync<InvalidOperationException>(
                () => machine.WaitForCompletionAsync(1000));

            var ex = Record.Exception(() => machine.Begin(10, 12));
            Assert.Null(ex);
            Assert.Equal(Fass2TaskPhase.Planning, machine.Context.Phase);
        }

        [Fact]
        public void PassingFirstStation_DoesNotRebuildForUnchangedFields()
        {
            var siteIds = new List<int> { 10, 11, 12 };
            var planCalls = 0;
            var taskIds = 0UL;
            var plan = ThreeStationPlan(siteIds);
            var machine = CreateMachine(
                () =>
                {
                    planCalls++;
                    return plan;
                },
                () => ++taskIds);

            machine.Begin(10, 12);
            machine.Tick(Report(1, moving: true, startStop: 1));
            machine.Tick(Report(1, moving: false, startStop: 1));
            machine.Tick(Report(1, moving: false, startStop: 1));
            machine.Tick(Report(1, moving: false, startStop: 1));
            Assert.Equal(1, machine.Context.CurrentIndex);
            Assert.Equal(1UL, machine.Context.TaskId);
            Assert.Equal(1, planCalls);

            var afterAdvance = machine.Tick(Report(2, moving: true, startStop: 1));
            Assert.False(afterAdvance.Rebuilt);
            Assert.Equal(1, planCalls);
            Assert.Equal(1UL, machine.Context.TaskId);
            Assert.Equal(1, machine.Context.CurrentIndex);
            Assert.Equal(Fass2TaskPhase.Moving, machine.Context.Phase);
        }

        [Fact]
        public void FirstPrepareTrafficFailure_WaitsInsteadOfFault()
        {
            var machine = CreateMachine(
                prepareTraffic: (_, __) => throw new InvalidOperationException("already locks it"));

            machine.Begin(10, 12);
            var tick = machine.Tick(Report(1, moving: true, startStop: 1));

            Assert.False(tick.Faulted);
            Assert.NotEqual(Fass2TaskPhase.Fault, machine.Context.Phase);
            Assert.Equal(Fass2TaskPhase.Moving, machine.Context.Phase);
            Assert.True(machine.Context.WaitingForTraffic);
            Assert.Contains("wait", tick.Message, StringComparison.OrdinalIgnoreCase);
        }

        [Fact]
        public void ZeroLockedWindow_DoesNotDispatch()
        {
            var sent = new List<Fass2NodeMessage[]>();
            var machine = CreateMachine(
                ensureWindow: (_, __, ___) => 0,
                onSendNodes: window => sent.Add(window));
            machine.LockCount = 1;

            machine.Begin(10, 12);
            machine.Tick(Report(1, moving: true, startStop: 1));

            Assert.Empty(sent);
            Assert.True(machine.Context.WaitingForTraffic);
            Assert.NotEqual(Fass2TaskPhase.Fault, machine.Context.Phase);
        }

        [Fact]
        public void AlarmBits_DoNotFaultTask()
        {
            var machine = CreateMachine();
            machine.Begin(10, 12);
            var tick = machine.Tick(Report(1, moving: true, startStop: 1, alarm: 1));

            Assert.False(tick.Faulted);
            Assert.NotEqual(Fass2TaskPhase.Fault, machine.Context.Phase);
        }

        [Fact]
        public void CatchUp_StopsAtUnfinishedStopStation()
        {
            var plan = new Fass2TaskPlan
            {
                StartSiteId = 10,
                GoalSiteId = 12,
                SiteIds = new List<int> { 10, 11, 12 },
                Nodes = new List<Fass2NodeMessage>
                {
                    new Fass2NodeMessage { Node = 1, StartStop = Fass2TaskBuilder.StartStopPass, Distance = 100 },
                    new Fass2NodeMessage { Node = 2, StartStop = Fass2TaskBuilder.StartStopStop },
                    new Fass2NodeMessage { Node = 3, StartStop = Fass2TaskBuilder.StartStopPass }
                },
                FieldsSignature = Fass2SiteFieldReader.BuildFieldsSignature(
                    new List<int> { 10, 11, 12 }, 0, SimpleLib.GetSite)
            };
            var machine = CreateMachine(() => plan, () => 1UL);
            machine.LockCount = 4;
            machine.Begin(10, 12);
            machine.Tick(Report(1, moving: true, startStop: 1));
            machine.Tick(Report(3, moving: true, startStop: 1));

            Assert.Equal(1, machine.Context.CurrentIndex);
        }

        [Fact]
        public async Task TrafficWait_TimesOutInsteadOfWaitingForever()
        {
            var machine = CreateMachine(
                prepareTraffic: (_, __) => throw new InvalidOperationException("already locks it"));
            machine.TrafficWaitTimeoutMs = 200;
            machine.Begin(10, 12);
            machine.Tick(Report(1, moving: true, startStop: 1));

            await Assert.ThrowsAsync<TimeoutException>(
                () => machine.WaitForCompletionAsync(10_000));
            Assert.True(machine.IsIdle);
        }

        private static Fass2TaskStateMachine CreateMachine(
            Func<Fass2TaskPlan> buildPlan = null,
            Func<ulong> allocateTaskId = null,
            Action<IReadOnlyList<int>, int> prepareTraffic = null,
            Func<IReadOnlyList<int>, int, int, int> ensureWindow = null,
            Action<Fass2NodeMessage[]> onSendNodes = null)
        {
            var plan = ThreeStationPlan(new List<int> { 10, 11, 12 });
            return new Fass2TaskStateMachine(new Fass2TaskCallbacks
            {
                BuildPlan = (_, __, ___) => buildPlan != null ? buildPlan() : plan,
                SendNodes = (window, _) => onSendNodes?.Invoke(window),
                SendAction = (_, __) => { },
                SendControl = (_, __) => { },
                ResolveNodeId = id => (ushort)id,
                AllocateTaskId = () => allocateTaskId != null ? allocateTaskId() : 1UL,
                AllocateActionId = () => 9UL,
                PrepareTraffic = prepareTraffic,
                EnsureTrafficWindow = ensureWindow
            })
            {
                StartBeforeMove = false,
                LockCount = 4,
                ResendIntervalMs = 60_000,
                ActionRetryIntervalMs = 0
            };
        }

        private static Fass2TaskPlan ThreeStationPlan(List<int> siteIds)
        {
            return new Fass2TaskPlan
            {
                StartSiteId = siteIds[0],
                GoalSiteId = siteIds[siteIds.Count - 1],
                SiteIds = siteIds,
                Nodes = new List<Fass2NodeMessage>
                {
                    new Fass2NodeMessage { Node = 1, StartStop = Fass2TaskBuilder.StartStopPass, Distance = 100 },
                    new Fass2NodeMessage { Node = 2, StartStop = Fass2TaskBuilder.StartStopPass, Distance = 100 },
                    new Fass2NodeMessage { Node = 3, StartStop = Fass2TaskBuilder.StartStopStop }
                },
                FieldsSignature = Fass2SiteFieldReader.BuildFieldsSignature(siteIds, 0, SimpleLib.GetSite)
            };
        }

        private static Fass2StateReport Report(ushort node, bool moving, byte startStop, byte alarm = 0, byte? state = null)
        {
            return new Fass2StateReport
            {
                State = state ?? (byte)(moving ? 1 : 2),
                Alarm = alarm,
                Node = new Fass2NodeMessage
                {
                    Node = node,
                    StartStop = startStop
                }
            };
        }
    }
}