From a19c28924d28f3633727bf86f92a0aaeb9ed7692 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 20 Dec 2025 15:11:51 +0000
Subject: Add utility for parsing an ISO like duration

---
 src/util.hpp       | 44 ++++++++++++++++++++++++++++++++++++++++++++
 test/Jamfile.jam   |  9 +++++++++
 test/test-util.cpp | 31 +++++++++++++++++++++++++++++++
 3 files changed, 84 insertions(+)
 create mode 100644 test/test-util.cpp

diff --git a/src/util.hpp b/src/util.hpp
index ad55604..8f2a585 100644
--- a/src/util.hpp
+++ b/src/util.hpp
@@ -1,6 +1,8 @@
 #pragma once
 
+#include <chrono>
 #include <command.h>
+#include <scn/scan.h>
 #include <tuple>
 
 namespace WebStat {
@@ -31,4 +33,46 @@ namespace WebStat {
 	{
 		(cmd->bindParam(firstParam++, std::forward<T>(param)), ...);
 	}
+
+	namespace detail {
+		template<typename Rep, typename Period, typename AddPeriod>
+		void
+		add(std::chrono::duration<Rep, Period> & subtotal, Rep value)
+		{
+			if constexpr (requires { subtotal += AddPeriod {value}; }) {
+				subtotal += AddPeriod {value};
+			}
+		}
+	}
+
+	template<typename Rep, typename Period>
+	std::chrono::duration<Rep, Period>
+	parseDuration(std::string_view input)
+	{
+		static constexpr std::initializer_list<
+				std::pair<void (*)(std::chrono::duration<Rep, Period> & subtotal, Rep value), std::string_view>>
+				DURATION_UNITS {
+						{detail::add<Rep, Period, std::chrono::milliseconds>, "ms"},
+						{detail::add<Rep, Period, std::chrono::seconds>, "s"},
+						{detail::add<Rep, Period, std::chrono::minutes>, "m"},
+						{detail::add<Rep, Period, std::chrono::hours>, "h"},
+						{detail::add<Rep, Period, std::chrono::days>, "d"},
+						{detail::add<Rep, Period, std::chrono::weeks>, "w"},
+				};
+
+		std::chrono::duration<Rep, Period> out {};
+		auto inputSubRange = scn::ranges::subrange {input};
+
+		while (auto result = scn::scan<Rep, std::string>(inputSubRange, "{}{:[a-z]}")) {
+			const auto & [count, chars] = result->values();
+			if (auto unit = std::ranges::find(
+						DURATION_UNITS, chars, &std::decay_t<decltype(*DURATION_UNITS.begin())>::second);
+					unit != DURATION_UNITS.end()) {
+				unit->first(out, count);
+			}
+			inputSubRange = result->range();
+		}
+
+		return out;
+	}
 }
diff --git a/test/Jamfile.jam b/test/Jamfile.jam
index 6574046..98c0d9a 100644
--- a/test/Jamfile.jam
+++ b/test/Jamfile.jam
@@ -21,6 +21,15 @@ lib testing-util :
 	<library>..//dbpp-postgresql
 	;
 
+run test-util.cpp : : :
+	<define>BOOST_TEST_DYN_LINK
+	<library>testing-util
+	<library>..//dbpp-postgresql
+	<library>boost_unit_test_framework
+	<library>dbpptestcore
+	<library>stdc++fs
+	;
+
 run test-ingest.cpp :
 	-- :
 	../src/schema.sql
diff --git a/test/test-util.cpp b/test/test-util.cpp
new file mode 100644
index 0000000..5850411
--- /dev/null
+++ b/test/test-util.cpp
@@ -0,0 +1,31 @@
+#define BOOST_TEST_MODULE ingest
+#include <boost/test/data/test_case.hpp>
+#include <boost/test/unit_test.hpp>
+
+#include <util.hpp>
+
+namespace WebStat {
+}
+
+using DurationParserData = std::tuple<std::string_view, std::chrono::milliseconds>;
+
+BOOST_TEST_DECORATOR(*boost::unit_test::timeout(1))
+
+BOOST_DATA_TEST_CASE(durationParser,
+		boost::unit_test::data::make<DurationParserData>({
+				{"", std::chrono::milliseconds {0}},
+				{"123ms", std::chrono::milliseconds {123}},
+				{"45s", std::chrono::seconds {45}},
+				{"10m", std::chrono::minutes {10}},
+				{"7h", std::chrono::hours {7}},
+				{"2d", std::chrono::days {2}},
+				{"7w", std::chrono::weeks {7}},
+				{"1w4d3h45m10s1ms",
+						std::chrono::weeks {1} + std::chrono::days {4} + std::chrono::hours {3}
+								+ std::chrono::minutes {45} + std::chrono::seconds {10}
+								+ std::chrono::milliseconds {1}},
+		}),
+		input, expected)
+{
+	BOOST_CHECK_EQUAL(expected, (WebStat::parseDuration<std::intmax_t, std::milli>(input)));
+}
-- 
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