namespace LivingVillage.Kernel.Tests

open Microsoft.VisualStudio.TestTools.UnitTesting
open LivingVillage.Kernel
open LivingVillage.Kernel.Sim

module private RumorHarness =

    let private needs =
        { Hunger = 100.0f
          Energy = 100.0f
          Social = 100.0f
          Money = 50.0f }

    let private personality =
        { Drive = 0.5f
          Aggression = 0.0f
          Extraversion = 0.8f
          Honesty = 0.5f
          Greed = 0.5f }

    let private npc id =
        { Id = NpcId id
          Pos = { X = float32 (id * 10); Y = 0.0f }
          Inventory = Map.empty
          Mind =
            { Needs = needs
              Personality = personality
              Action = Wander
              Target = actionTarget Wander
              ActionAge = minActionTicks
              EffectDone = true
              HungerFlagged = false
              Memory = [] } }

    let world tick count =
        { Tick = tick
          Time = float tick * dtSeconds
          Rng = Rng.ofSeed 11UL
          Avatar =
              { Pos = { X = 0.0f; Y = 0.0f }
                Mind =
                    { Needs = needs
                      Personality = personality
                      Action = Wander
                      Target = actionTarget Wander
                      ActionAge = 0L
                      EffectDone = false
                      HungerFlagged = false
                      Memory = [] } }
          NoHost = { Reserved = 0UL }
          Npcs = Array.init count npc
          Events = []
          Rumors = []
          RumorCount = 0
          RumorOldestDay = System.Int64.MaxValue
          Annals = [] }

    let readyForChat (world: World) : World =
        { world with
            Npcs =
                world.Npcs
                |> Array.map (fun npc ->
                    { npc with
                        Mind =
                            { npc.Mind with
                                Action = Wander
                                Target = actionTarget Wander
                                ActionAge = minActionTicks
                                EffectDone = true } }) }

    let chat narrator receiver world =
        match Sim.chat { Narrator = NpcId narrator; Receiver = NpcId receiver } world with
        | ChatSucceeded (_, next) -> next
        | ChatRejected (failure, _) -> Assert.Fail($"chat rejected: {failure}"); Unchecked.defaultof<World>

    let rumorId (RumorId id) = id

    let orderedRumors (world: World) =
        world.Rumors |> List.sortBy (fun rumor -> rumorId rumor.Id)

    let traceText (world: World) =
        orderedRumors world
        |> List.map (fun rumor ->
            let parent = rumor.Parent |> Option.map rumorId |> Option.map string |> Option.defaultValue "-"
            sprintf "%d|%d|%d|%d|%d|%s|%d"
                (rumorId rumor.Id)
                rumor.Tick
                (match rumor.Source with NpcId id -> id)
                (match rumor.Narrator with NpcId id -> id)
                (match rumor.Receiver with NpcId id -> id)
                parent
                rumor.Depth)
        |> String.concat "\n"

    let rumor id tick dayIndex =
        { Id = RumorId id
          Tick = tick
          DayIndex = dayIndex
          OriginTick = tick
          Source = NpcId 0
          Narrator = NpcId 0
          Receiver = NpcId 1
          Parent = None
          Depth = 0
          Strength = 1.0f }

    let withRumorBudget capacity retentionDays action =
        let previousCapacity = rumorCapacity
        let previousRetention = rumorRetentionDays
        rumorCapacity <- capacity
        rumorRetentionDays <- retentionDays
        try
            action ()
        finally
            rumorCapacity <- previousCapacity
            rumorRetentionDays <- previousRetention

[<TestClass>]
type RumorTests () =

    [<TestMethod>]
    member _.IdleChatsCreateThreeHopTraceableRumorPathWithinTwoDays () =
        let initial = RumorHarness.world 0L 4
        let first = RumorHarness.chat 0 1 initial
        let second = RumorHarness.chat 1 2 (RumorHarness.readyForChat { first with Tick = ticksPerDay })
        let third = RumorHarness.chat 2 3 (RumorHarness.readyForChat { second with Tick = 2L * ticksPerDay })
        let ordered = RumorHarness.orderedRumors third

        Assert.AreEqual<int>(3, third.Rumors.Length)
        Assert.AreEqual<int>(3, ordered.Length)
        let root = ordered.[0]
        let retelling = ordered.[1]
        let final = ordered.[2]
        Assert.AreEqual<NpcId>(NpcId 0, root.Source)
        Assert.AreEqual<NpcId>(NpcId 0, root.Narrator)
        Assert.AreEqual<NpcId>(NpcId 1, root.Receiver)
        Assert.IsTrue(root.Parent.IsNone)
        Assert.AreEqual<int>(0, root.Depth)
        Assert.AreEqual<RumorId>(root.Id, retelling.Parent |> Option.get)
        Assert.AreEqual<NpcId>(root.Source, retelling.Source)
        Assert.AreEqual<NpcId>(NpcId 1, retelling.Narrator)
        Assert.AreEqual<NpcId>(NpcId 2, retelling.Receiver)
        Assert.AreEqual<int>(1, retelling.Depth)
        Assert.AreEqual<RumorId>(retelling.Id, final.Parent |> Option.get)
        Assert.AreEqual<NpcId>(NpcId 2, final.Narrator)
        Assert.AreEqual<NpcId>(NpcId 3, final.Receiver)
        Assert.AreEqual<int>(2, final.Depth)

        let path = Sim.rumorPath third final.Id
        CollectionAssert.AreEqual([| root; retelling; final |], List.toArray path)

    [<TestMethod>]
    member _.DuplicateRetellingDoesNotCreateAnotherRumorNode () =
        let first = RumorHarness.chat 0 1 (RumorHarness.world 0L 3)
        let second = RumorHarness.chat 1 2 (RumorHarness.readyForChat first)
        let duplicate = RumorHarness.chat 1 2 (RumorHarness.readyForChat second)

        Assert.AreEqual<int>(2, second.Rumors.Length)
        Assert.AreEqual<int>(2, duplicate.Rumors.Length)
        Assert.AreEqual<string>(RumorHarness.traceText second, RumorHarness.traceText duplicate)

    [<TestMethod>]
    member _.StaleRumorIsNotUsedAsParentForAReTelling () =
        let first = RumorHarness.chat 0 1 (RumorHarness.world 0L 3)
        let stale =
            first
            |> RumorHarness.readyForChat
            |> fun world -> { world with Tick = rumorFreshnessTicks + 1L }
        let next = RumorHarness.chat 1 2 stale
        let latest = RumorHarness.orderedRumors next |> List.last

        Assert.IsTrue(latest.Parent.IsNone, "stale memory must not be reused as a parent")
        Assert.IsTrue(latest.Source = NpcId 1, "a stale rumor starts a new local source")
        Assert.IsTrue(Sim.rumorStrengthAt next.Tick (RumorHarness.orderedRumors next |> List.head) < rumorMinimumStrength)

    [<TestMethod>]
    member _.InvalidParticipantsLeaveWorldUnchanged () =
        let before = RumorHarness.world 10L 2
        let requests =
            [ { Narrator = NpcId 9; Receiver = NpcId 1 }
              { Narrator = NpcId 0; Receiver = NpcId 9 }
              { Narrator = NpcId 0; Receiver = NpcId 0 } ]

        for request in requests do
            match Sim.chat request before with
            | ChatRejected (_, unchanged) -> Assert.AreEqual<World>(before, unchanged)
            | ChatSucceeded _ -> Assert.Fail($"expected invalid chat to be rejected: {request}")

    [<TestMethod>]
    member _.SameSeedAndChatOperationsProduceIdenticalRumorTrace () =
        let run seed =
            let initial = { RumorHarness.world 0L 4 with Rng = Rng.ofSeed seed }
            let first = RumorHarness.chat 0 1 initial
            let second = RumorHarness.chat 1 2 (RumorHarness.readyForChat { first with Tick = ticksPerDay })
            let third = RumorHarness.chat 2 3 (RumorHarness.readyForChat { second with Tick = 2L * ticksPerDay })
            RumorHarness.traceText third

        Assert.AreEqual<string>(run 4242UL, run 4242UL)

    [<TestMethod>]
    member _.RumorTraceTextContainsStableMetadataAndReplayablePaths () =
        let initial = RumorHarness.world 0L 4
        let first = RumorHarness.chat 0 1 initial
        let second = RumorHarness.chat 1 2 (RumorHarness.readyForChat { first with Tick = ticksPerDay })
        let third = RumorHarness.chat 2 3 (RumorHarness.readyForChat { second with Tick = 2L * ticksPerDay })

        let expected =
            String.concat "\n"
                [ sprintf "rumor_trace tick=%d count=3" (2L * ticksPerDay)
                  "rumor id=0 tick=0 origin_tick=0 source=0 narrator=0 receiver=1 parent=- depth=0 strength=1.000000 path=0"
                  sprintf "rumor id=1 tick=%d origin_tick=0 source=0 narrator=1 receiver=2 parent=0 depth=1 strength=0.500000 path=0,1" ticksPerDay
                  sprintf "rumor id=2 tick=%d origin_tick=0 source=0 narrator=2 receiver=3 parent=1 depth=2 strength=0.250000 path=0,1,2" (2L * ticksPerDay) ]

        Assert.AreEqual<string>(expected, Sim.rumorTraceText third)

    [<TestMethod>]
    member _.TrimWithinCapacityAndFreshWindowIsZeroCopy () =
        RumorHarness.withRumorBudget 4 3L (fun () ->
            let rumors =
                [ RumorHarness.rumor 3L (3L * ticksPerDay) 3L
                  RumorHarness.rumor 2L (2L * ticksPerDay) 2L
                  RumorHarness.rumor 1L (1L * ticksPerDay) 1L ]
            let trimmed = Sim.trimRumors (3L * ticksPerDay) rumors
            Assert.IsTrue(System.Object.ReferenceEquals(rumors, trimmed), "within budget the list must be returned as-is")
            Assert.AreEqual<RumorEvent list>(rumors, trimmed))

    [<TestMethod>]
    member _.TrimCapsToNewestRumors () =
        RumorHarness.withRumorBudget 4 30L (fun () ->
            let rumors = List.init 6 (fun index -> RumorHarness.rumor (int64 (5 - index)) (10L * ticksPerDay) 10L)
            let trimmed = Sim.trimRumors (10L * ticksPerDay) rumors
            Assert.AreEqual<int>(4, trimmed.Length)
            let keptIds = trimmed |> List.map (fun rumor -> RumorHarness.rumorId rumor.Id)
            CollectionAssert.AreEqual([| 5L; 4L; 3L; 2L |], List.toArray keptIds))

    [<TestMethod>]
    member _.TrimDropsRumorsOlderThanRetentionWindow () =
        RumorHarness.withRumorBudget 100 3L (fun () ->
            let rumors =
                [ RumorHarness.rumor 3L (10L * ticksPerDay) 10L
                  RumorHarness.rumor 2L (9L * ticksPerDay) 9L
                  RumorHarness.rumor 1L (6L * ticksPerDay) 6L
                  RumorHarness.rumor 0L (5L * ticksPerDay) 5L ]
            let trimmed = Sim.trimRumors (10L * ticksPerDay) rumors
            let keptIds = trimmed |> List.map (fun rumor -> RumorHarness.rumorId rumor.Id)
            CollectionAssert.AreEqual([| 3L; 2L |], List.toArray keptIds)
            Assert.AreEqual<RumorEvent list>(trimmed, Sim.trimRumors (10L * ticksPerDay) trimmed))

    [<TestMethod>]
    member _.ChatKeepsWorkingSetWithinCapacityAndIdsStayMonotonic () =
        RumorHarness.withRumorBudget 1 30L (fun () ->
            let first = RumorHarness.chat 0 1 (RumorHarness.world 0L 4)
            let second = RumorHarness.chat 1 2 (RumorHarness.readyForChat first)
            Assert.AreEqual<int>(1, first.Rumors.Length)
            Assert.AreEqual<int>(1, second.Rumors.Length)
            let head = second.Rumors |> List.head
            Assert.AreEqual<int64>(1L, RumorHarness.rumorId head.Id)
            Assert.AreEqual<RumorId option>(Some(RumorId 0L), head.Parent))

    [<TestMethod>]
    member _.CappedRumorsWithinCapacitySaveByteIdenticallyToUncapped () =
        let run capacity =
            RumorHarness.withRumorBudget capacity 30L (fun () ->
                let first = RumorHarness.chat 0 1 (RumorHarness.world 0L 4)
                let second = RumorHarness.chat 1 2 (RumorHarness.readyForChat { first with Tick = ticksPerDay })
                WorldSave.save second)
        Assert.AreEqual<string>(run 8, run System.Int32.MaxValue)

    [<TestMethod>]
    member _.RumorDayIndexMirrorsTickAndSurvivesSaveRoundTrip () =
        let world = RumorHarness.chat 0 1 (RumorHarness.world 0L 3)
        let rumor = world.Rumors |> List.head
        Assert.AreEqual<int64>(rumor.Tick / ticksPerDay, rumor.DayIndex)
        match WorldSave.load (WorldSave.save world) with
        | Error failure -> Assert.Fail($"round trip should load: {failure}")
        | Ok restored ->
            Assert.AreEqual<RumorEvent list>(world.Rumors, restored.Rumors)
            Assert.AreEqual<int64>(rumor.DayIndex, (restored.Rumors |> List.head).DayIndex)