<div id="app"></div>

<script>

var N =
{
    ID:{
        Walk:0,
        Instance:0
    },

    Create(inMeta)
    {
        return {
            ID:{
                Walk:0,
                Instance:N.ID.Instance++
            },
            Meta:inMeta||{},
            Link:{}
        };
    },
    Connect(inNodeMajor, inNodeMinor, inKey, inUnique)
    {
        if(inUnique) // bail if the nodes are already connected
        {
            let check = N.Step(inNodeMajor, inKey, true);
            if(check)
            {
                if(check.indexOf(inNodeMinor) < 0)
                {
                    return;
                }
            }
        }
        N.Step(inNodeMajor, inKey, true, true).push(inNodeMinor);
        N.Step(inNodeMinor, inKey, false, true).push(inNodeMajor);
    },
    Disconnect(inNodeMajor, inNodeMinor, inKey)
    {
        let remove = (inArray, inMatch) => inArray.findIndex( (inMember, inIndex, inArray) => (inMember === inMatch) ? inArray.splice(inIndex, 1) : false );

        // if no specific child was passed
        if(inNodeMinor === null)
        {
            // get all the children
            let check = N.Step(inNodeMajor, inKey);
            if(!check){ return; }

            // go down to each child ...
            check.forEach( inNodeMinor => 
            {
                let connections = inNodeMinor.Link[inKey];
                remove( connections.Get, inNodeMajor); // ... and remove any reference to the parent

                // if after the remove operation, this child has no connections on inKey, scrub the key
                if(!connections.Set.length && !connections.Get.length)
                {
                    delete inNodeMinor.Link[inKey];
                }
            });

            // we just wiped out all outgoing connections to the parent, if incoming connections are empty too we can purge the key there as well
            if(inNodeMajor.Link[inKey].Get.length == 0)
            {
                delete inNodeMajor.Link[inKey];
            }
            return;
        }

        // if no specific parent was passed
        if(inNodeMajor === null)
        {
            // get all the parents
            let check = N.Step(inNodeMinor, inKey, false);
            if(!check){ return; }
            
            // go up to each parent ...
            check.forEach( inNodeMajor => 
            {
                let connections = inNodeMajor.Link[inKey];
                remove( connections.Set, inNodeMinor); // ... and remove any reference to the child
                
                // if after the remove operation, this parent has no connections on inKey, scrub the key
                if( !connections.Set.length && !connections.Get.length )
                {
                    delete inNodeMajor.Link[inKey];
                }
            });

            // we just wiped out all incoming connections to the child, if outgoing connections are empty too we can purge the key there as well
            if(inNodeMinor.Link[inKey].Set.length == 0)
            {
                delete inNodeMinor.Link[inKey];
            }
            return;
        }

        // if a specific parent and child were passed
        if(inNodeMajor.Link[inKey].Set.length == 1)
        {
            delete inNodeMajor.Link[inKey];
        }
        else
        {
            remove(inNodeMajor.Link[inKey].Set, inNodeMinor);
        }
        if(inNodeMinor.Link[inKey].Get.length == 1)
        {
            delete inNodeMinor.Link[inKey];
        }
        else
        {
            remove(inNodeMinor.Link[inKey].Get, inNodeMajor);
        }

    },
    Step(inNode, inKey, inForward, inForceCreate)
    {
        let connectionGroup = inNode.Link[inKey];
        if(!connectionGroup)
        {
            if(inForceCreate === true)
            {
                inNode.Link[inKey] = connectionGroup = {Get:[], Set:[]};
            }
            else
            {
                return false;
            }
        }
        return (inForward === undefined || inForward === true) ? connectionGroup.Set : connectionGroup.Get;
        
    },
    Walk(inIterator, inNode, inKey, inForward, inTerminal)
    {
        let array = N.Step(inNode, inKey, inForward);

        if(!array.length && inTerminal)
        {
            return inTerminal(inNode);
        }

        for(let i=0; i<array.length; i++)
        {
            let next = array[i];
            if(next.ID.Walk !== N.ID.Walk)
            {
                next.ID.Walk = N.ID.Walk;
                let results = inIterator(next);
                if(results !== false)
                {
                    N.Walk(inIterator, next, inKey, inForward, inTerminal);
                }
            }
        }
    },
    Path(inArray, inNode, inKey, inForward)
    {
        var current = inNode;
        var direction = inForward||true;
        for(let i=0; i<inArray.length; i++)
        {
            current = N.Step(current, inKey, direction)[inArray[i]];
        }
        return current;
    }
};
</script>

<script>
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++)
        {
            N.Connect(Pivot.Schema, N.Create({Label:inColumnNames[i], Index:i}), inColumnTypes[i]);
        }
        Pivot.Leaves = inRows.map(r => N.Create({Row:r}));
        Pivot.Init = ()=>{};
    },
    Pivot(inRoot, inParent, inPivotIndicies, inSumIndicies, inDepth)
    {
        //arguments:
        //    - a Node with leaf Nodes temporarily stored in its Meta.Leaves
        //        - where each leaf Node has a row of table data in it's Meta.Row
        //    - a list of columns to pivot on
        //    - a list of columns to sum
        //    - optional traversal depth, defaults to 0
        let depth = inDepth||0;
        let uniques = {};
        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[inPivotIndicies[depth]]; // 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, 
                    Leaves:[]
                };
                // 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;
        var iterator;
        if(depth >= inPivotIndicies.length-1)
        {
            iterator = inLastBranch =>
            {
                N.Connect(inRoot, inLastBranch, "Terminal");
                inLastBranch.Meta.Leaves.forEach( inLeaf =>
                {
                    // collect modifiers effecting leaves
                    let modifiers = [];
                    let check = N.Step(inLeaf, "ModifyAt", false);
                    if(check)
                    {
                        modifiers = modifiers.concat(check);
                    }
                    check = N.Step(inLeaf, "ModifyDown", false);
                    if(check)
                    {
                        modifiers = modifiers.concat(check);
                    }

                    if(modifiers.length)
                    {
                        // apply them to the branch
                        inLastBranch.ID.Walk = N.ID.Walk;
                        modifiers.forEach( inModifier => N.Connect(inModifier, inLastBranch, "ModifyUp") )

                        // also walk them up and connect, but with "check unique" enabled
                        N.Walk( inNode=>
                        {
                            modifiers.forEach( inModifier => N.Connect(inModifier, inNode, "ModifyUp", true) )
                        }
                        , inLastBranch, "Hierarchy", false);
                    }

                    // lastly connect the leaf to the branch
                    N.Connect(inLastBranch, inLeaf, "Hierarchy");
                });
                delete inLastBranch.Meta.Leaves;
            }
        }
        else
        {
            iterator = child => Pivot.Pivot(inRoot, child, inPivotIndicies, inSumIndicies, depth+1);
        }
        N.Step(inParent, "Hierarchy").forEach(iterator);
        return inParent;
    },
    Create(inPivotIndicies, inSumIndicies)
    {
        N.ID.Walk++;
        
        let pivotRoot = N.Create({Label:"Pivot Root", Leaves:Pivot.Leaves});
        N.Connect(Pivot.Root, pivotRoot, "Pivot");
        return Pivot.Pivot(pivotRoot, pivotRoot, inPivotIndicies, inSumIndicies);
    },
    Delete(inRoot)
    {
        // disconnect modifiers
        let check = N.Step(inRoot, "Modifier");
        if(check)
        {
            while(check.length>0)
            {
                Pivot.Unmodify(check[0]);
            }
        }

        // disconnect terminal branches
        N.Walk(()=>{}, inRoot, "Terminal", inNode=>{
            N.Disconnect(inNode, null, "Hierarchy");
        });

        // disconnect from app
        N.Disconnect(null, inRoot, "Pivot")
    },
    Modify(inNode)
    {
        let modified = N.Create({Label:"Modifier"});
        N.ID.Walk++;
        if(N.Step(inNode, "Hierarchy").length)
        {
            N.Walk(()=>{}, inNode, "Hierarchy", false, (inRoot)=>
            {
                N.Connect(inRoot, modified, "Modifier");
            });
        }
        else
        {
            N.Connect(Pivot.Root, modified, "Modifier");
        }

        let leaves = [];
        let gatherUp = n => N.Connect(modified, n, "ModifyUp");
        let gatherDown = n =>
        {
            N.Connect(modified, n, "ModifyDown");
            N.Step(n, "Hierarchy").length == 0 ?  leaves.push(n) : null;
        };
        let gatherOut = n => N.Connect(modified, n, "ModifyOut");

        N.ID.Walk++;
        inNode.ID.Walk = N.ID.Walk;
        N.Connect(modified, inNode, "ModifyAt");

        N.Walk(gatherUp, inNode, "Hierarchy", false);
        N.Walk(gatherDown, inNode, "Hierarchy");
        leaves.forEach(leaf=>N.Walk(gatherOut, leaf, "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");
    }
};
</script>

<script type="module">

import { h, render, createContext, Fragment } from 'https://cdn.skypack.dev/preact';
import { useReducer } from 'https://cdn.skypack.dev/preact/hooks';
import { css, cx } from 'https://cdn.skypack.dev/@emotion/css';

Pivot.Init(
    ["number", "type-a", "type-b", "count"],
    ["label", "label", "label", "sum"],
    [
    ["#1", "a", "long",  1, 4],
    ["#2", "b", "long",  2, 4],
    ["#3", "b", "short", 2, 4],
    ["#4", "a", "long",  3, 4],
    ["#5", "b", "short", 1, 4],
    ["#6", "a", "short", 0, 4],
    ["#7", "b", "short", 7, 4]
    ]
);

let ElForm = props =>
{
    let labelColumns = N.Step(Pivot.Schema, "label")||[];

    let used = N.Step(Pivot.Proto, "used")||[];
    let unused = N.Step(Pivot.Schema, "label").filter( columnLabel => !N.Step(columnLabel, "used", false) );
    let indicies = used.map(node=>node.Meta.Index);

    var action;
    if(indicies.length)
    {
        action = h("div", null, [
            h("span", null, "Build"),
            h("button", {onClick:e=>
            {
                N.Disconnect(Pivot.Proto, null, "used");
                Pivot.Create(indicies, [3, 4]);
                Render();
            }
            }, indicies)
        ]);
    }
    else
    {
        action = h("div", null, "(select columns)")
    }

    return h("div", {}, [
        h("div", null, [
            h("span", null, "available"),
            ...unused.map( node=>
            {
                return h("button", {onClick:e=>
                {
                    N.Connect(Pivot.Proto, node, "used");
                    Render();
                }
                }, node.Meta.Label);
            }
            )
        ]),
        h("div", null, [
            h("span", null, "taken"),
            ...used.map( node=>
            {
                return h("button", {onClick:e=>
                {
                    N.Disconnect(Pivot.Proto, node, "used");
                    Render();
                }
                }, node.Meta.Label);
            }
            )
        ]),
        action
    ])
};

let ElNode = ({node, depth}) =>
{
    let nodeBase = css`
        position:relative;
        padding:0;
        margin:0;
        border-top:1px solid lightgrey;

        .Table
        {
            display:inline-block;
            text-align:right;
        }
        .Cell
        {
            width:50px;
            display:inline-block;
            padding:10px;
        }
    `;
    let label = css`
        display:inline-block;
        width:200px;

        &::before
        {
            content:" ";
            display:inline-block;
            width:${depth*15}px;
        }
        .Modify
        {
            float:right;
        }
    `;

    let icon = cx(
        {
            [css`
                display:inline-block;
                width:0px;
                height:0px;
                border:7px solid white;`        ]: true,
            [css`border-bottom-color:lightblue;`]: N.Step(node, "ModifyUp"  ),
            [css`border-top-color:orange;`      ]: N.Step(node, "ModifyDown"),
            [css`border-left-color:grey;`       ]: N.Step(node, "ModifyOut" ),
            [css`border-right-color:red;`       ]: N.Step(node, "ModifyAt"  )
        },
    );

    let buttonModify = h("span", {
        className:"Icon Modify Add",
        onClick:e=>
        {
            Pivot.Modify(node);
            Render();
        }
    }, "Modify");

    let buttonUnmodify = h("span", {
        className:"Icon Modify remove",
        onClick:e=>
        {
            Pivot.Unmodify(N.Step(node, "ModifyAt", false)[0]);
            Render();
        }
    }, "Unmodify");

    return h("div", {className:"Node"}, [
        h("div", {className:cx(nodeBase, "Upper")}, [
            h("div", {className:label}, [
                h("span", {className:"Icon Expand"}, "+"),
                h("span", {className:"Name"}, (node.Meta.Label || "a node")+" "+node.ID.Walk),
                h("span", {className: icon}),
                N.Step(node, "ModifyAt") ? buttonUnmodify : buttonModify
            ] ),
            h("div", {className:"Table"}, (node.Meta.Row || []).map( cell => h("div", {className:"Cell"}, cell)) )
        ]),
        h("div", {className:"Nodes"}, N.Step(node, "Hierarchy").map(child=>h(ElNode, {node:child, depth:depth+1})) )
    ]);
};
let ElPivot = ({pivot}) =>
{   
    return h("div", {style:{display:"inline-block", width:"800px"}}, [
        h("button", {onClick:e=>{Pivot.Delete(pivot);Render();}}, "delete?"),
        h(ElModifiers, {node:pivot}),
        h(ElNode, {node:pivot, depth:0})
    ]);
};
let ElModifiers = ({node}) =>
{
    let modifiers = N.Step(node, "Modifier") || [];

    return h("div", null, [
        h("strong", null, "modifiers"),
        ...modifiers.map( m => h("span", {onClick:e=>
        {
            Pivot.Unmodify(m);
            Render();
        }
        }, "modifier"))
    ]);
};
let ElRoot = props =>
{
    let pivots = N.Step(Pivot.Root, "Pivot")||[];
    return h("div", null, [
        h("h3", null, "tree view"),
        h(ElForm),
        h(ElModifiers, {node:Pivot.Root}),
        pivots.map(pivot=>h(ElPivot, {pivot}))
    ])
};
let Render = () => render(h(ElRoot), document.querySelector("#app"));
Render();

</script>