From 4a9a4078ad32aaaa61092f4043f4835090d99138 Mon Sep 17 00:00:00 2001
From: RunasSudo <runassudo@yingtongli.me>
Date: Sun, 23 Feb 2025 00:07:47 +1100
Subject: [PATCH] Implement comparative balance sheet report

---
 src/reports/BalanceSheetReport.vue | 115 +++++++++++++++++++++++++----
 1 file changed, 99 insertions(+), 16 deletions(-)

diff --git a/src/reports/BalanceSheetReport.vue b/src/reports/BalanceSheetReport.vue
index 21ef25c..bfb135e 100644
--- a/src/reports/BalanceSheetReport.vue
+++ b/src/reports/BalanceSheetReport.vue
@@ -1,6 +1,6 @@
 <!--
 	DrCr: Web-based double-entry bookkeeping framework
-	Copyright (C) 2022–2024  Lee Yingtong Li (RunasSudo)
+	Copyright (C) 2022–2025  Lee Yingtong Li (RunasSudo)
 	
 	This program is free software: you can redistribute it and/or modify
 	it under the terms of the GNU Affero General Public License as published by
@@ -61,7 +61,23 @@
 <!-- Report display -->
 
 <template>
-	<DynamicReportComponent :report="report">
+	<ComparativeDynamicReportComponent :reports="reports" :labels="reportLabels">
+		<div class="my-2 py-2 flex">
+			<div class="grow flex gap-x-2 items-baseline">
+				<span class="whitespace-nowrap">As at</span>
+				<input type="date" class="bordered-field" v-model.lazy="dt">
+				<span>Compare</span>
+				<div class="relative flex flex-grow items-stretch shadow-sm">
+					<input type="number" min="1" class="bordered-field w-[9.5em] pr-[6em]" v-model.lazy="comparePeriods">
+					<div class="absolute inset-y-0 right-0 flex items-center z-10">
+						<select class="h-full border-0 bg-transparent py-0 pl-2 pr-8 text-gray-900 focus:ring-2 focus:ring-inset focus:ring-emerald-600" v-model="compareUnit">
+							<option value="years">years</option>
+							<option value="months">months</option>
+						</select>
+					</div>
+				</div>
+			</div>
+		</div>
 		<div class="rounded-md bg-red-50 mt-4 p-4 col-span-2" v-if="!doesBalance">
 			<div class="flex">
 				<div class="flex-shrink-0">
@@ -72,38 +88,105 @@
 				</div>
 			</div>
 		</div>
-	</DynamicReportComponent>
+	</ComparativeDynamicReportComponent>
 </template>
 
 <script setup lang="ts">
-	import { computed, ref } from 'vue';
+	import { computed, ref, watch } from 'vue';
+	import dayjs from 'dayjs';
 	
 	import { ExclamationCircleIcon } from '@heroicons/vue/20/solid';
 	
 	import { Computed, DynamicReport, Entry, Section, Spacer, Subtotal } from './base.ts';
 	import { IncomeStatementReport}  from './IncomeStatementReport.vue';
 	import { db } from '../db.ts';
-	import DynamicReportComponent from '../components/DynamicReportComponent.vue';
+	import { ExtendedDatabase } from '../dbutil.ts';
+	import ComparativeDynamicReportComponent from '../components/ComparativeDynamicReportComponent.vue';
 	import { ReportingStage, ReportingWorkflow } from '../reporting.ts';
 	
-	const report = ref(null as BalanceSheetReport | null);
+	const reports = ref([] as BalanceSheetReport[]);
+	const reportLabels = ref([] as string[]);
+	
+	const dt = ref(null as string | null);
+	const comparePeriods = ref(1);
+	const compareUnit = ref('years');
 	
 	async function load() {
 		const session = await db.load();
-		const reportingWorkflow = new ReportingWorkflow();
-		await reportingWorkflow.generate(session);
 		
-		report.value = reportingWorkflow.getReportAtStage(ReportingStage.FINAL_STAGE, BalanceSheetReport) as BalanceSheetReport;
+		dt.value = db.metadata.eofy_date;
+		
+		await updateReport(session);
+		
+		// Update report when dates etc. changed
+		// We initialise the watcher here only after dt and dtStart are initialised above
+		watch([dt, comparePeriods, compareUnit], async () => {
+			const session = await db.load();
+			await updateReport(session);
+		});
 	}
 	load();
 	
-	const doesBalance = computed(function() {
-		if (report.value === null) {
-			return true;
+	async function updateReport(session: ExtendedDatabase) {
+		const newReportPromises = [];
+		const newReportLabels = [];
+		for (let i = 0; i < comparePeriods.value; i++) {
+			let thisReportDt, thisReportLabel;
+			
+			// Get period end date
+			if (compareUnit.value === 'years') {
+				thisReportDt = dayjs(dt.value!).subtract(i, 'year');
+				thisReportLabel = dayjs(dt.value!).subtract(i, 'year').format('YYYY');
+			} else if (compareUnit.value === 'months') {
+				if (dayjs(dt.value!).add(1, 'day').isSame(dayjs(dt.value!).set('date', 1).add(1, 'month'))) {
+					// If dt is the end of a calendar month, then fix each prior dt to be the end of the calendar month
+					thisReportDt = dayjs(dt.value!).subtract(i, 'month').set('date', 1).add(1, 'month').subtract(1, 'day');
+				} else {
+					thisReportDt = dayjs(dt.value!).subtract(i, 'month');
+				}
+				thisReportLabel = dayjs(dt.value!).subtract(i, 'month').format('YYYY-MM');
+			} else {
+				throw new Error('Unexpected compareUnit');
+			}
+			
+			// Get start of financial year date
+			let sofyDayjs = dayjs(db.metadata.eofy_date).subtract(1, 'year').add(1, 'day');
+			let thisReportDtStart = thisReportDt.set('date', sofyDayjs.get('date')).set('month', sofyDayjs.get('month'));
+			if (thisReportDtStart.isAfter(thisReportDt)) {
+				thisReportDtStart = thisReportDtStart.subtract(1, 'year');
+			}
+			
+			console.log([thisReportDt, thisReportDtStart]);
+			
+			// Generate reports asynchronously
+			newReportPromises.push((async () => {
+				const reportingWorkflow = new ReportingWorkflow();
+				await reportingWorkflow.generate(session, thisReportDt.format('YYYY-MM-DD'), thisReportDtStart.format('YYYY-MM-DD'));
+				return reportingWorkflow.getReportAtStage(ReportingStage.FINAL_STAGE, BalanceSheetReport) as BalanceSheetReport;
+			})());
+			
+			if (comparePeriods.value === 1) {
+				// If only 1 report, the heading is simply "$"
+				newReportLabels.push(db.metadata.reporting_commodity);
+			} else {
+				newReportLabels.push(thisReportLabel);
+			}
 		}
-		const totalAssets = (report.value.byId('total_assets') as Computed).quantity;
-		const totalLiabilities = (report.value.byId('total_liabilities') as Computed).quantity;
-		const totalEquity = (report.value.byId('total_equity') as Computed).quantity;
-		return totalAssets === totalLiabilities + totalEquity;
+		
+		reports.value = await Promise.all(newReportPromises);
+		reportLabels.value = newReportLabels;
+	}
+	
+	const doesBalance = computed(function() {
+		let doesBalance = true;
+		for (const report of reports.value) {
+			const totalAssets = (report.byId('total_assets') as Computed).quantity;
+			const totalLiabilities = (report.byId('total_liabilities') as Computed).quantity;
+			const totalEquity = (report.byId('total_equity') as Computed).quantity;
+			if (totalAssets !== totalLiabilities + totalEquity) {
+				doesBalance = false;
+			}
+		}
+		return doesBalance;
 	});
 </script>