#include "snapshots.h"

static void _snapshot_stack_push(SnapshotStack* stack, Snapshot* snapshot)
{
    if (stack->top >= SNAPSHOT_STACK_MAX)
    {
        for (s32 i = 0; i < SNAPSHOT_STACK_MAX - 1; i++)
            stack->snapshots[i] = stack->snapshots[i + 1];
        stack->top = SNAPSHOT_STACK_MAX - 1;
    }
    stack->snapshots[stack->top++] = *snapshot;
}

static Snapshot* _snapshot_stack_pop(SnapshotStack* stack)
{
    if (stack->top == 0) return nullptr;
    return &stack->snapshots[--stack->top];
}

static void _snapshot_set(Snapshots* self, Snapshot* snapshot)
{
    if (!snapshot) return;

    *self->anm2 = snapshot->anm2;
    *self->reference = snapshot->reference;
    self->preview->time = snapshot->time;
    self->action = snapshot->action;

    anm2_spritesheet_texture_pixels_upload(self->anm2);
}

Snapshot snapshot_get(Snapshots* self)
{
    Snapshot snapshot = {*self->anm2, *self->reference, self->preview->time, self->action};
    anm2_spritesheet_texture_pixels_download(&snapshot.anm2);
    return snapshot;
}

void snapshots_init(Snapshots* self, Anm2* anm2, Anm2Reference* reference, Preview* preview)
{
    self->anm2 = anm2;
    self->reference = reference;
    self->preview = preview;
}

void snapshots_reset(Snapshots* self)
{
    self->undoStack = SnapshotStack{};
    self->redoStack = SnapshotStack{};
    self->action.clear();
}

void snapshots_undo_push(Snapshots* self, Snapshot* snapshot)
{
    self->redoStack.top = 0;
    _snapshot_stack_push(&self->undoStack, snapshot);
}

void snapshots_undo(Snapshots* self)
{
    if (Snapshot* snapshot = _snapshot_stack_pop(&self->undoStack))
    {
        Snapshot current = snapshot_get(self);
        _snapshot_stack_push(&self->redoStack, &current);
        _snapshot_set(self, snapshot);
    }
}

void snapshots_redo(Snapshots* self)
{
    if (Snapshot* snapshot = _snapshot_stack_pop(&self->redoStack))
    {
        Snapshot current = snapshot_get(self);
        _snapshot_stack_push(&self->undoStack, &current);
        _snapshot_set(self, snapshot);
    }
}