Add calculation and disply for average of incomes and expenses

frontend/css/base.css

@@ -461,3 +461,19 @@ td .status-indicator {
 .options td:nth-child(2) {
   white-space: normal;
 }
+/*
+ * Incomes Expenses Average
+ */
+.inc_exp_avg_row {
+  display: flex;
+  flex-wrap: wrap;
+}
+.inc_exp_avg_column {
+  flex: 1;
+}
+.inc_exp_avg_header {
+  font-weight: 400;
+  background-color: var(--table-header-background);
+  border: 1px solid var(--table-border);
+  text-align: center;
+}

src/fava/application.py

@@ -11,10 +11,12 @@
 """
 from __future__ import annotations
 
+from collections import defaultdict
 from dataclasses import fields
 from datetime import date
 from datetime import datetime
 from functools import lru_cache
+from functools import reduce
 from io import BytesIO
 from pathlib import Path
 from threading import Lock
@@ -25,6 +27,7 @@
 from urllib.parse import urlunparse
 
 import markdown2  # type: ignore[import]
+from _decimal import Decimal
 from beancount import __version__ as beancount_version
 from beancount.utils.text_utils import replace_numbers
 from flask import abort
@@ -66,6 +69,9 @@
     from flask.wrappers import Response
     from werkzeug import Response as WerkzeugResponse
 
+    from fava.core.charts import DateAndBalanceWithBudget
+    from fava.internal_api import ChartData
+
 
 setup_logging()
 
@@ -163,9 +169,62 @@ def _setup_template_config(fava_app: Flask) -> None:
     fava_app.add_template_global(get_ledger_data, "get_ledger_data")
 
     @fava_app.context_processor
-    def _template_context() -> dict[str, FavaLedger | type[ChartApi]]:
+    def _template_context() -> (
+        dict[
+            str,
+            FavaLedger
+            | type[ChartApi]
+            | tuple[dict[str, Decimal], dict[str, Decimal]],
+        ]
+    ):
         """Inject variables into the template context."""
-        return {"ledger": g.ledger, "chart_api": ChartApi}
+        incomes_expenses_averages = _calculate_chart_average()
+
+        return {
+            "ledger": g.ledger,
+            "chart_api": ChartApi,
+            "incomes_expenses_averages": incomes_expenses_averages,
+        }
+
+
+def _calculate_chart_average() -> (
+    tuple[dict[str, Decimal], dict[str, Decimal]]
+):
+    income_interval_totals: ChartData = ChartApi.interval_totals(
+        g.interval, g.ledger.options["name_income"], ""
+    )
+    expense_interval_totals: ChartData = ChartApi.interval_totals(
+        g.interval, g.ledger.options["name_expenses"], ""
+    )
+
+    def sum_balances(
+        total_balances: dict[str, Decimal], d: DateAndBalanceWithBudget
+    ) -> dict[str, Decimal]:
+        for key, value in d.balance.items():
+            total_balances[key] = total_balances[key] + value
+        return total_balances
+
+    income_balances: dict[str, Decimal] = reduce(
+        sum_balances,
+        income_interval_totals.data,
+        defaultdict(lambda: Decimal(0)),
+    )
+    expense_balances: dict[str, Decimal] = reduce(
+        sum_balances,
+        expense_interval_totals.data,
+        defaultdict(lambda: Decimal(0)),
+    )
+
+    income_averages = {
+        ib[0]: ib[1] / len(income_interval_totals.data)
+        for ib in income_balances.items()
+    }
+    expense_averages = {
+        ib[0]: ib[1] / len(expense_interval_totals.data)
+        for ib in expense_balances.items()
+    }
+
+    return income_averages, expense_averages
 
 
 def _setup_filters(fava_app: Flask, read_only: bool, incognito: bool) -> None:

src/fava/templates/income_statement.html

@@ -3,6 +3,8 @@
 {% set root_tree = g.filtered.root_tree %}
 {% set options = ledger.options %}
 {% set invert = ledger.fava_options.invert_income_liabilities_equity %}
+{% set incomesAverage =  incomes_expenses_averages[0]%}
+{% set expensesAverage =  incomes_expenses_averages[1]%}
 
 <svelte-component type="charts"><script type="application/json">{{
   [
@@ -14,6 +16,35 @@
   ]|tojson
 }}</script></svelte-component>
 
+<div class="row">
+  <div class="column">
+    <div class="inc_exp_avg_header">Incomes Average</div>
+    {% for inc_average in incomes_expenses_averages[0] %}
+    <div class="inc_exp_avg_row">
+      <div class="inc_exp_avg_column">
+        {{inc_average}}
+      </div>
+      <div class="inc_exp_avg_column">
+        {{incomesAverage[inc_average] | format_currency}}
+      </div>
+    </div>
+    {% endfor %}
+  </div>
+  <div class="column">
+    <div class="inc_exp_avg_header">Expenses Average</div>
+    {% for exp_average in incomes_expenses_averages[1] %}
+    <div class="inc_exp_avg_row">
+      <div class="inc_exp_avg_column">
+        {{exp_average}}
+      </div>
+      <div class="inc_exp_avg_column">
+        {{expensesAverage[exp_average] | format_currency}}
+      </div>
+    </div>
+    {% endfor %}
+  </div>
+</div>
+
 <div class="row">
   <div class="column">
     {{ tree_table.tree(root_tree.get(options['name_income']), invert=invert) }}

tests/test_application.py

@@ -8,10 +8,12 @@
 from beancount import __version__ as beancount_version
 
 from fava import __version__ as fava_version
+from fava.application import _calculate_chart_average
 from fava.application import create_app
 from fava.application import SERVER_SIDE_REPORTS
 from fava.application import static_url
 from fava.context import g
+from fava.template_filters import format_currency
 
 if TYPE_CHECKING:  # pragma: no cover
     from pathlib import Path
@@ -264,3 +266,19 @@ def test_load_extension_reports(test_client: FlaskClient) -> None:
     url = "/extension-report/extension/MissingExtension/"
     result = test_client.get(url)
     assert result.status_code == 404
+
+
+def test_calculate_average_income_expenses(app: Flask) -> None:
+    with app.test_request_context("/long-example/?interval=year"):
+        app.preprocess_request()
+        averages = _calculate_chart_average()
+        income_averages = averages[0]
+        expenses_averages = averages[1]
+
+        assert format_currency(income_averages["IRAUSD"]) == "-3147.06"
+        assert format_currency(income_averages["USD"]) == "-18309.54"
+        assert format_currency(income_averages["VACHR"]) == "-18.24"
+
+        assert format_currency(expenses_averages["IRAUSD"]) == "2723.53"
+        assert format_currency(expenses_averages["USD"]) == "13142.98"
+        assert format_currency(expenses_averages["VACHR"]) == "23.06"