import computeToggles from '/imports/api/engine/computation/computeComputation/computeToggles.js';
import computeByType from '/imports/api/engine/computation/computeComputation/computeByType.js';
import embedInlineCalculations from './utility/embedInlineCalculations.js';
import path from 'ngraph.path';

export default function computeCreatureComputation(computation){
  const stack = [];
  // Computation scope of {variableName: prop}
  const graph = computation.dependencyGraph;
  // Add all nodes to the stack
  graph.forEachNode(node => {
    node._visited = false;
    node._visitedChildren = false;
    stack.push(node)
  });

  // The graph nodes in the stack are ordered, by reversing the order we
  // compute higher nodes in the tree first, which for dep loops is more likely
  // to be a good guess of where to start thant the inverse
  stack.reverse();

  // Depth first traversal of nodes
  while (stack.length){
    let top = stack[stack.length - 1];
    if (top._visited){
      // The object has already been computed, skip
      stack.pop();
    } else if (top._visitedChildren){
      // Mark the object as visited and remove from stack
      top._visited = true;
      stack.pop();
    // Compute the top object of the stack
      compute(computation, top);
    } else {
      top._visitedChildren = true;
      // Push dependencies to graph to be computed first
      pushDependenciesToStack(top.id, graph, stack, computation);
    }
  }

  // Finish the props after the dependency graph has been traversed
  computation.props.forEach(finalizeProp);
}

function compute(computation, node){
  // Determine the prop's active status by its toggles
  computeToggles(computation, node);
  // Compute the property by type
  computeByType[node.data?.type || '_variable']?.(computation, node);
}

function pushDependenciesToStack(nodeId, graph, stack, computation){
  graph.forEachLinkedNode(nodeId, linkedNode => {
    if (linkedNode._visitedChildren && !linkedNode._visited){
      const pather = path.nba(graph, {
        oriented: true
      });
      const loop = pather.find(nodeId, nodeId);
      computation.errors.push({
        type: 'dependencyLoop',
        details: {
          nodes: loop.map(node => node.id)
        },
      });
    }
    stack.push(linkedNode);
  }, true);
}

function finalizeProp(prop){
  // Embed the inline calculations
  prop._computationDetails?.inlineCalculations?.forEach(inlineCalcObj => {
    embedInlineCalculations(inlineCalcObj);
  });
  // Clean up the computation details
  delete prop._computationDetails;
}