static keyframe*
KeyframeLookup(property_channel *Property, int16 i) {
    int16 b = i / MAX_KEYFRAMES_PER_BLOCK;
    int16 k = i - b*MAX_KEYFRAMES_PER_BLOCK;
    return &Property->KeyframeBlock[b]->Keyframe[k];
}

static keyframe*
PushKeyframe(property_channel *Property) {
    int16 i = Property->NumberOfTotalKeyframes;
    int16 b = i / MAX_KEYFRAMES_PER_BLOCK;
    int16 k = i - b*MAX_KEYFRAMES_PER_BLOCK;
    return &Property->KeyframeBlock[b]->Keyframe[k];
}

static temp_keyframe_list
GetSelectedKeyframes(project_data *File)
{
    temp_keyframe_list KeyframeList;
    int z = 0;
    for (int i = 0; i < File->NumberOfLayers; i++) {
        for (int a = 0; a < AmountOf(File->Layer[i]->Property); a++) {
            for (int l = 0; l < File->Layer[i]->Property[a].NumberOfTotalKeyframes; l++) {
                keyframe *Keyframe = KeyframeLookup(&File->Layer[i]->Property[a], l);
                if (Keyframe->IsSelected) {
                    KeyframeList.SelectedKeyframe[z] = Keyframe;
                    z++;
                }
            }
        }
    }
    KeyframeList.Amount = z;
    return KeyframeList;
}

static void
SelectKeyframe(project_data *File, project_layer *Layer, property_channel *Property, keyframe *Keyframe)
{
    Layer->IsSelected = true;
    File->NumberOfSelectedLayers++;
    Property->NumberOfSelectedKeyframes++;
    Keyframe->IsSelected = true;
}

static void
DeselectKeyframe(project_data *File, project_layer *Layer, property_channel *Property, keyframe *Keyframe)
{
    Layer->IsSelected = true;
    File->NumberOfSelectedLayers++;
    Property->NumberOfSelectedKeyframes++;
    Keyframe->IsSelected = true;
}

static void
CheckKeyframeSort(property_channel *Property, int32 Increment, int32 b)
{
    /*
    int32 i = KeyframeMemoryToIndex(Property, b);
    if (Increment > 0) {
        if (i+1 != Property->NumberOfTotalKeyframes) {
            keyframe *CurrentKeyframe = KeyframeLookupIndex(Property, i);
            keyframe *NextKeyframe = KeyframeLookupIndex(Property, i + 1);
            if (NextKeyframe->FrameNumber < CurrentKeyframe->FrameNumber) {
                uint16 Temp = Property->SortedIndex[i];
                Property->SortedIndex[i] = Property->SortedIndex[i + 1];
                Property->SortedIndex[i + 1] = Temp;
            }
        }
    } else {
        if (i != 0) {
            keyframe *CurrentKeyframe = KeyframeLookupIndex(Property, i);
            keyframe *LastKeyframe = KeyframeLookupIndex(Property, i - 1);
            if (CurrentKeyframe->FrameNumber < LastKeyframe->FrameNumber) {
                uint16 Temp = Property->SortedIndex[i];
                Property->SortedIndex[i] = Property->SortedIndex[i - 1];
                Property->SortedIndex[i - 1] = Temp;
            }
        }
    }
    */
}


static void
ResortPropertyChannel(property_channel *Property) {
    /*
    for (int16 i = 0; i < Property->NumberOfTotalKeyframes; i++)
    {
        Property->SortedIndex[i] = i;
    }
    for (;;) {
        int16 Swaps = 0;
        for (int16 i = 0; i < Property->NumberOfTotalKeyframes - 1; i++)
        {
            keyframe *Keyframe = KeyframeLookupIndex(Property, i);
            keyframe *NextKeyframe = KeyframeLookupIndex(Property, i + 1);
            if (Keyframe->FrameNumber > NextKeyframe->FrameNumber) {
                uint16 Temp = Property->SortedIndex[i];
                Property->SortedIndex[i] = Property->SortedIndex[i + 1];
                Property->SortedIndex[i + 1] = Temp;
                Swaps++;
            }
        }
        if (Swaps == 0)
            break;
    }
    */
}

static void
Keyframe_ShiftPointers(property_channel *Property, int16 Increment, int16 StopAt) {
    if (Increment > 0) {
        int16 i = Property->NumberOfTotalKeyframes - 1;
        while (i >= StopAt) {
            keyframe *CurrentKeyframe = KeyframeLookup(Property, i);
            keyframe *NextKeyframe = KeyframeLookup(Property, i + Increment);
            *NextKeyframe = *CurrentKeyframe;
            i--;
        }
    } else  {
        int16 i = StopAt;
        while (i <= Property->NumberOfTotalKeyframes - 1) {
            keyframe *CurrentKeyframe = KeyframeLookup(Property, i);
            keyframe *NextKeyframe = KeyframeLookup(Property, i - Increment);
            *CurrentKeyframe = *NextKeyframe;
            i++;
        }
    }
}


static void
DeleteSelectedKeyframes(project_data *File, memory *Memory)
{
    for (int i = 0; i < File->NumberOfLayers; i++) {
        for (int a = 0; a < AmountOf(File->Layer[i]->Property); a++) {
            property_channel *Property = &File->Layer[i]->Property[a];
            for (int l = 0; l < Property->NumberOfTotalKeyframes; l++) {
                keyframe *Keyframe = KeyframeLookup(Property, l);
                if (Keyframe->IsSelected) {
                    int16 ToShift = 1;
                    bool32 Until = true;
                    while (Until) {
                        keyframe *KeyframeN = KeyframeLookup(Property, l + ToShift);
                        if (KeyframeN->IsSelected) {
                            ToShift += 1;
                        } else {
                            Until = false;
                        }
                    }
                    Keyframe_ShiftPointers(Property, -ToShift, l);
                }
            }
            ResortPropertyChannel(Property);
        }
    }
}

static void
IncrementKeyframes(property_channel *Property, int16 Increment)
{
    /*
    for (int i = 0; i < Property->NumberOfTotalKeyframes; i++) {
        keyframe *Keyframe = KeyframeLookupIndex(Property, i);
        Keyframe->FrameNumber += Increment;
    }
    */
}

static void
IncrementKeyframesInLayer(project_layer *Layer, int16 Increment)
{
    for (int a = 0; a < AmountOf(Layer->Property); a++)
        IncrementKeyframes(&Layer->Property[a], Increment);
    for (int e = 0; e < Layer->NumberOfEffects; e++)
        for (int a = 0; a < Layer->Effect[e]->NumberOfProperties; a++)
            IncrementKeyframes(&Layer->Effect[e]->Property[a], Increment);
}

static void
CreateKeyframeBlock(property_channel *, memory *);

// dir 0 left, 1 right
static void
ClampKeyframeHandles(property_channel *Property, int16 b, int16 dir) {
    if (dir == 0) {
        if (b > 0) {
            keyframe *Keyframe = KeyframeLookup(Property, b - 1);
            keyframe *NextKeyframe = KeyframeLookup(Property, b);
            real32 XSpan = NextKeyframe->FrameNumber - Keyframe->FrameNumber;
            // TODO(fox): Fix this!
#if WINDOWS
            if (NextKeyframe->TangentLeft.x > XSpan)
#else
            if (abs(NextKeyframe->TangentLeft.x) > XSpan)
#endif
                NextKeyframe->TangentLeft.x = -XSpan;
            if (NextKeyframe->TangentLeft.x > 0)
                NextKeyframe->TangentLeft.x = 0;
        }
    }
    if (dir == 1) {
        if (b < Property->NumberOfTotalKeyframes - 1) {
            keyframe *Keyframe = KeyframeLookup(Property, b);
            keyframe *NextKeyframe = KeyframeLookup(Property, b + 1);
            real32 XSpan = NextKeyframe->FrameNumber - Keyframe->FrameNumber;
            if (Keyframe->TangentRight.x > XSpan)
                Keyframe->TangentRight.x = XSpan;
            if (Keyframe->TangentRight.x < 0)
                Keyframe->TangentRight.x = 0;
        }
    }
}

static void
ClampSurroundingKeyframeHandles(property_channel *Property, int16 b) {
    ClampKeyframeHandles(Property, b, 0);
    ClampKeyframeHandles(Property, b, 1);
    if (b > 0) {
        ClampKeyframeHandles(Property, b-1, 0);
        ClampKeyframeHandles(Property, b-1, 1);
    }
    if (b < Property->NumberOfTotalKeyframes - 1) {
        ClampKeyframeHandles(Property, b+1, 0);
        ClampKeyframeHandles(Property, b+1, 1);
    }
}

static uint32
Keyframe_FindClosestIndex(property_channel *Property, int32 CurrentFrame, bool32 *Overlapping)
{
    if (Property->NumberOfTotalKeyframes == 0) {
        *Overlapping = false;
        return 0;
    } else {
        uint32 Index = Property->NumberOfTotalKeyframes;
        for (;;) {
            keyframe *PreviousKeyframe = KeyframeLookup(Property, Index - 1);
            keyframe *NextKeyframe = KeyframeLookup(Property, Index + 1);
            if (PreviousKeyframe->FrameNumber < CurrentFrame) {
                if (NextKeyframe->FrameNumber >= CurrentFrame) {
                    keyframe *CurrentKeyframe = KeyframeLookup(Property, Index);
                    if (CurrentKeyframe->FrameNumber == CurrentFrame)  {
                        *Overlapping = true;
                        return Index;
                    } else {
                        if (CurrentKeyframe->FrameNumber > CurrentFrame) {
                            *Overlapping = false;
                            return Index;
                        } else {
                            *Overlapping = false;
                            return Index + 1;
                        }
                    }
                } else if (Index == Property->NumberOfTotalKeyframes) {
                    *Overlapping = false;
                    return Index;
                } else {
                    Index += (Property->NumberOfTotalKeyframes - Index) / 2;
                }
            // We can only progress from this first if statement if
            // NextKeyframe is valid, so we need to check for these conditions.
            } else if (Property->NumberOfTotalKeyframes == 1) {
                keyframe *Keyframe = KeyframeLookup(Property, 0);
                *Overlapping = (Keyframe->FrameNumber == CurrentFrame);
                Index = 0;
                return Index;
            } else if (Property->NumberOfTotalKeyframes == 2) {
                // We know we're smaller than index 1, so we just need to compare 0.
                keyframe *FirstKeyframe = KeyframeLookup(Property, 0);
                Index = (FirstKeyframe->FrameNumber > CurrentFrame) ? 0 : 1;
                keyframe *Keyframe = KeyframeLookup(Property, Index);
                *Overlapping = (Keyframe->FrameNumber == CurrentFrame);
                return Index;
            } else if (Index == 0) {
                keyframe *CurrentKeyframe = KeyframeLookup(Property, Index);
                if (CurrentKeyframe->FrameNumber == CurrentFrame)  {
                    *Overlapping = true;
                    return Index;
                } else {
                    Assert(0);
                }
            } else {
                Index = Index / 2;
            }
        }
    }
}

// NOTE(fox): Delete calls need to increment the total number before shifting!
static void
Keyframe_Delete(property_channel *Property, memory *Memory, uint32 Index)
{
    History_Entry_Commit(Memory, action_entry_default, "Delete keyframe");
    keyframe *KeyframeIndex = KeyframeLookup(Property, Index);
    History_Action_StoreData(Memory, KeyframeIndex, sizeof(keyframe));

    History_Action_Change_Decrement(Memory, &Property->NumberOfTotalKeyframes, action_type_change_u16);
    History_Action_Shift(Memory, action_type_shift_keyframe, Property, -1, Index);
    Keyframe_ShiftPointers(Property, -1, Index);
    History_Entry_End(Memory);
}

static void
Keyframe_Insert(property_channel *Property, memory *Memory, int32 CurrentFrame, real32 Val)
{
    if (!(Property->NumberOfTotalKeyframes % MAX_KEYFRAMES_PER_BLOCK)) {
        CreateKeyframeBlock(Property, Memory);
    }
    keyframe *Keyframe = NULL;
    bool32 Overlapping = 0;
    uint32 Index = Keyframe_FindClosestIndex(Property, CurrentFrame, &Overlapping);
    Keyframe = KeyframeLookup(Property, Index);
    if (Overlapping && Val == Keyframe->Value.f)
        return;
    if (!Overlapping) {
        History_Entry_Commit(Memory, action_entry_default, "Insert keyframe");
        if (Index != Property->NumberOfTotalKeyframes) {
            History_Action_Shift(Memory, action_type_shift_keyframe, Property, 1, Index);
            Keyframe_ShiftPointers(Property, 1, Index);
        }

        History_Action_Change_Increment(Memory, &Property->NumberOfTotalKeyframes, action_type_change_u16);
        History_Action_Change(Memory, &Keyframe->FrameNumber, &Keyframe->FrameNumber, &CurrentFrame, action_type_change_i32);
        History_Action_Change_Increment(Memory, &RandomGlobalIncrement, action_type_change_u32);
        History_Action_Change(Memory, &Keyframe->ImguiID, &Keyframe->ImguiID, &RandomGlobalIncrement, action_type_change_u32);

        Keyframe->Type = bezier;
        Keyframe->TangentLeft = V2(-1, 0);
        Keyframe->TangentRight = V2(1, 0);
    } else {
        History_Entry_Commit(Memory, action_entry_default, "Adjust keyframe value");
    }
    History_Action_Change(Memory, &Keyframe->Value.f, &Keyframe->Value.f, &Val, action_type_change_r32);
    // Keyframe->Value.f = Val;

    History_Entry_End(Memory);
}


static void
CalculateKeyframesLinearly(uint16 CurrentFrame, struct property_channel *Property)
{
  keyframe *FirstKeyframe = KeyframeLookup(Property, 0);

  keyframe *LastKeyframe = KeyframeLookup(Property, Property->NumberOfTotalKeyframes - 1);
  if (Property->NumberOfTotalKeyframes == 0) {
      // do nothing
  }
    // check if current frame is before first keyframe or after last
  else if (Property->NumberOfTotalKeyframes == 1 ||
          CurrentFrame < FirstKeyframe->FrameNumber) {
          Property->CurrentValue = FirstKeyframe->Value;
  }
  else if (CurrentFrame > LastKeyframe->FrameNumber) {
          Property->CurrentValue = LastKeyframe->Value;
  }
  else if (Property->NumberOfTotalKeyframes > 1) {
    for (int i = 0; i < (Property->NumberOfTotalKeyframes - 1); i++) {
      keyframe *Keyframe = KeyframeLookup(Property, i);
      keyframe *NextKeyframe = KeyframeLookup(Property, i+1);
      if (CurrentFrame >= Keyframe->FrameNumber &&
          CurrentFrame <= NextKeyframe->FrameNumber)
      {
        real32 FakeVelocity = ((CurrentFrame - Keyframe->FrameNumber) /
                              (NextKeyframe->FrameNumber -
                              (real32)Keyframe->FrameNumber));
         real32 t = FakeVelocity;
        // real32 u = 1.0f - t;
        // real32 w1 = u * u * u;
        // real32 w2 = 3 * u * u * t;
        // real32 w3 = 3 * u * t * t;
        // real32 w4 = t * t * t;
        real32 t2 = t * t;
        real32 t3 = t2 * t;
        real32 mt = 1-t;
        real32 mt2 = mt * mt;
        real32 mt3 = mt2 * mt;
        if (Property->VarType == type_real ) {
          real32 OldValue = Property->CurrentValue.f;
          real32 CurrentVal = Keyframe->Value.f;
          real32 CurrentTan = CurrentVal + Keyframe->TangentRight.y;
          real32 NextVal = NextKeyframe->Value.f;
          real32 NextTan = NextVal + NextKeyframe->TangentLeft.y;
          // Property->CurrentValue.f = w1 * CurrentVal + w2 * CurrentTan + w3 * NextTan + w4 * NextVal;
          Property->CurrentValue.f = CurrentVal*mt3 + 3*CurrentTan*mt2*t + 3*NextTan*mt*t2 + NextVal*t3;
          //Property->CurrentValue.f = CurrentVal + ((NextVal - CurrentVal) * FakeVelocity);
        }
        else if (Property->VarType == type_color) {
          v4 OldValue = Property->CurrentValue.col;
          v4 CurrentVal = Keyframe->Value.col;
          v4 NextVal = NextKeyframe->Value.col;
          Property->CurrentValue.col = CurrentVal + ((NextVal - CurrentVal) * FakeVelocity);
        }
          break;
      }
    }
  }
}