pivot-editor/Pivot.js

var Pivot = 
{
    Leaves:{},
    Root:N.Create({Label:"All Pivots"}),
    Schema:N.Create({Label:"Column Details"}),
    Proto:N.Create({Label:"User Form"}),
    Init(inColumnNames, inColumnTypes, inRows)
    {        
        for(let i=0; i<inColumnNames.length; i++)
        {
            let columnNode = N.Create({Label:inColumnNames[i], Index:i});
            N.Connect(Pivot.Schema, columnNode, inColumnTypes[i]);
            N.Connect(Pivot.Schema, columnNode, "all");
        }
        Pivot.Leaves = inRows.map(r => N.Create({Row:r}));
        Pivot.Init = ()=>{};
    },
    Create(inPivotIndicies, inSumIndicies)
    {
        N.ID.Walk++;
        
        let columns = N.Step(Pivot.Schema, "all");
        let label = inPivotIndicies.map( inPivotIndex =>
        {
            return columns[inPivotIndex].Meta.Label;
        });

        let pivotRoot = N.Create({Label:label.join("|"), Leaves:Pivot.Leaves});
        N.Connect(Pivot.Root, pivotRoot, "Pivot");
        return Pivot.Pivot(pivotRoot, pivotRoot, inPivotIndicies, inSumIndicies);
    },
    Pivot(inRoot, inParent, inPivotIndicies, inSumIndicies, inDepth)
    {


        let depth = inDepth||0;
        let uniques = {};
        let indexPivot = inPivotIndicies[depth];
        if(!inParent.Meta.Leaves)
        {
            console.log("problem")
        }
        // create a set of new nodes off of the input node
        inParent.Meta.Leaves.forEach((inLeaf)=>
        {
            let row = inLeaf.Meta.Row; // shorthand for the raw "CSV" row in the leaf Node's Meta
            let value = row[indexPivot]; // get the pivot column
            let match = uniques[value]; // check in the uniques list if this pivot column exists
            if(!match)
            {
                // if not, store a value under that key that will be the meta object for a new child

                let clone = row.map(r=>null);
                inSumIndicies.forEach((inSumIndex, inIndex, inArray)=>
                {
                    clone[inSumIndex] = row[inSumIndex]
                });
                match = uniques[value] = {
                    Label:value,
                    Row:clone, 
                    IndexPivot:indexPivot,
                    IndexSum:inSumIndicies,
                    Leaves:[],
                    Depth:depth
                };
                // grow a child off of the parent using the meta object
                N.Connect(inParent, N.Create(match), "Hierarchy");
            }
            else
            {
                // if a match does exist, sum the appropriate columns
                inSumIndicies.forEach((inSumIndex) => match.Row[inSumIndex] += row[inSumIndex]);
            }
            // move the leaves into the child
            match.Leaves.push(inLeaf);
        });
        
        delete inParent.Meta.Leaves;
        let iterator = () => {};
        if(depth >= inPivotIndicies.length-1)
        {
            iterator = inLastBranch =>
            {
                inLastBranch.Meta.Leaves.forEach( inLeaf =>
                {
                    // collect modifiers effecting leaves
                    let modifiers = [];
                    let collectModifier = n => modifiers.push(n);
                    let connectModifiers = n => 
                    {
                        modifiers.forEach(inModifier => N.Connect(inModifier, n, "ModifyOut", true));
                    };
                    
                    N.Walk(collectModifier, inLeaf, "ModifyAt",   false);
                    N.Walk(collectModifier, inLeaf, "ModifyDown", false);


                    if(modifiers.length)
                    {
                        // apply them to the branch
                        inLastBranch.ID.Walk = N.ID.Walk;
                        connectModifiers(inLastBranch);

                        // also walk them up and connect, but with "check unique" enabled
                        console.log("walking modifiers up from", inLastBranch.Meta.Label);
                        N.ID.Walk++;
                        N.Walk(connectModifiers, inLastBranch, "Hierarchy", false);
                    }

                    // lastly connect the leaf to the branch
                    N.Connect(inLastBranch, inLeaf, "Leaf");

                });
                delete inLastBranch.Meta.Leaves;
            }
        }
        else
        {
            iterator = child => {
                if(child.Meta.Label == "b")
                {
                    console.log("at b for some reason");
                }
                Pivot.Pivot(inRoot, child, inPivotIndicies, inSumIndicies, depth+1);
            };
        }

        N.Walk(iterator, inParent, "Hierarchy");
        
        return inParent;
    },
    Delete(inRoot)
    {
        // disconnect modifiers
        let check = N.Step(inRoot, "ModifyUp", false);
        if(check)
        {
            while(check.length>0)
            {
                Pivot.Unmodify(check[0]);
            }
        }

        // disconnect leaves from terminal branches
        N.Walk(()=>{}, inRoot, "Hierarchy", true, terminal=>{
            N.Disconnect(terminal, null, "Leaf");
        });

        // disconnect from app
        N.Disconnect(null, inRoot, "Pivot");
    },
    Modify(inNode)
    {
        let modified = N.Create({Label:"Modifier"});

        // traverse
        let gatherUp   = n => N.Connect(modified, n, "ModifyUp");
        let gatherDown = n => N.Connect(modified, n, "ModifyDown");
        let gatherOut  = n => N.Connect(modified, n, "ModifyOut");

        N.ID.Walk++;
        inNode.ID.Walk = N.ID.Walk;
        
        // at
        N.Connect(modified, inNode, "ModifyAt");
        
        // up
        N.Walk(gatherUp, inNode, "Hierarchy", false);

        // down 1
        N.Walk(gatherDown, inNode, "Hierarchy", true, terminal=>
        {
            // down 2
            // for each terminal node, step down into its leaves and gather down
            N.Walk(gatherDown, terminal, "Leaf", true, leaf=>
            {
                // out 1
                // walk back up on the leaf connections on other trees
                N.Walk(gatherOut, leaf, "Leaf", false, terminal=>
                {   
                    // out 2
                    // and continueup the hierarchy
                    N.Walk(gatherOut, terminal, "Hierarchy", false);
                });
            });
        });

        return modified;
    },
    Unmodify(inModifier)
    {
        N.Disconnect(inModifier, null, "ModifyUp");
        N.Disconnect(inModifier, null, "ModifyDown");
        N.Disconnect(inModifier, null, "ModifyOut");
        N.Disconnect(inModifier, null, "ModifyAt");
        N.Disconnect(null, inModifier, "Modifier");
    }
};