feat(General Ledger): prune empty accounts

This commit makes sure empty accounts are pruned from the General Ledger
report.

server/controllers/finance/generalLedger/index.js

@@ -113,46 +113,57 @@ function listAccounts(req, res, next) {
     .done();
 }
 
+const PERIODS = [
+  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
+];
+
+
 /**
  * @function getAccountTotalsMatrix
  *
  * @description
- * This function gets the period totals for all general ledger accounts from the
- * period totals table.
+ * This function gets the period totals for all accounts in a single fiscal
+ * year.  Returns only accounts (and their parents) that contain balances.
  */
 function getAccountTotalsMatrix(fiscalYearId) {
-  const periodNumbers = [
-    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
-  ];
-
   // this creates a series of columns that only sum values if they are in the
-  // correct periodNumber.
-  const periodColumns = periodNumbers.reduce(
+  // correct period.
+  const columns = PERIODS.reduce(
     (q, number) => `${q}, SUM(IF(p.number = ${number}, pt.debit - pt.credit, 0)) AS balance${number}`,
     ''
   );
 
+  const outerColumns =
+    PERIODS.map(number => `IFNULL(s.balance${number}, 0) AS balance${number}`)
+      .join(', ');
+
   // we want to show every single account, so we do a left join of the account
   // table
   const sql = `
     SELECT a.id, a.number, a.label, a.type_id, a.label, a.parent,
-      SUM(pt.debit - pt.credit) AS balance ${periodColumns}
-    FROM account AS a
-      LEFT JOIN period_total AS pt ON a.id = pt.account_id
+      IFNULL(s.balance, 0) AS balance, ${outerColumns}
+    FROM account AS a LEFT JOIN (
+      SELECT SUM(pt.debit - pt.credit) AS balance, pt.account_id ${columns}
+      FROM period_total AS pt
       JOIN period AS p ON p.id = pt.period_id
-    WHERE pt.fiscal_year_id = ?
-    GROUP BY a.id
+      WHERE pt.fiscal_year_id = ?
+      GROUP BY pt.account_id
+    )s ON a.id = s.account_id
     ORDER BY a.number;
   `;
 
+  //  returns true if all the balances are 0
+  const isEmptyRow = (row) => row.balance === 0;
+
   return db.exec(sql, [fiscalYearId])
     .then(accounts => {
       const accountsTree = new Tree(accounts);
 
       // compute the values of the title accounts as the values of their children
       accountsTree.sumOnProperty('balance');
-      periodNumbers.forEach(number => accountsTree.sumOnProperty(`balance${number}`));
+      PERIODS.forEach(number => accountsTree.sumOnProperty(`balance${number}`));
 
-      return accountsTree.toArray();
+      // prune empty rows
+      return accountsTree.prune(isEmptyRow);
     });
 }

server/lib/Tree.js

@@ -8,6 +8,7 @@
  * in the tree.
  */
 const _ = require('lodash');
+const debug = require('debug')('TreeBuilder');
 
 /**
  * @function buildTreeFromArray
@@ -16,6 +17,8 @@ const _ = require('lodash');
  * This function makes a tree data structure from a properly formatted array.
  */
 function buildTreeFromArray(nodes, parentId, parentKey) {
+  debug(`#builtTreeFromArray() called with (Array(${nodes.length}), ${parentId}, ${parentKey}.`);
+
   // recursion base-case:  return nothing if empty array
   if (nodes.length === 0) { return null; }
 
@@ -67,7 +70,7 @@ function flatten(tree, depth, pruneChildren = true) {
  * of their children for a given property.
  */
 function sumOnProperty(node, prop) {
-  if (node.children.length > 0) {
+  if (hasChildren(node)) {
     // recursively compute the value of node[prop] by summing all child[prop]s
     node[prop] = node.children.reduce((value, child) =>
       value + sumOnProperty(child, prop), 0);
@@ -76,6 +79,20 @@ function sumOnProperty(node, prop) {
   return node[prop];
 }
 
+function hasChildren(node) {
+  return node.children.length > 0;
+}
+
+function markNodeToPrune(node, fn) {
+  if (hasChildren(node)) {
+    node.children.forEach(child => markNodeToPrune(child, fn));
+  }
+
+  if (fn(node)) {
+    node._toPrune = true;
+  }
+}
+
 class Tree {
   constructor(data = [], options = {
     parentKey : 'parent',
@@ -86,8 +103,25 @@ class Tree {
     this._parentKey = options.parentKey;
     this._rootId = options.rootId;
 
+
     // build the tree with the provided root id and parentKey
     this._tree = buildTreeFromArray(_.cloneDeep(data), this._rootId, this._parentKey);
+
+    debug(`#constructor() built tree with ${this._data.length} nodes.`);
+  }
+
+  prune(fn) {
+    debug('#prune() called on tree strucure.');
+    // walk down the tree, marking nodes to be pruned.
+    this._tree.forEach(node => markNodeToPrune(node, fn));
+
+    const prev = this.toArray();
+    const pruned = prev.filter(node => !node._toPrune);
+
+    debug(`#prune() removed ${prev.length - pruned.length} nodes from the tree`);
+
+    // return an array missing the pruned values
+    return pruned;
   }
 
   toArray() {