Template:Category/Workshop itinerary/local-time

Convert a UTC "HH:MM" time string to a local time string given an offset in hours. Used by Template:Category/Workshop itinerary/session-row to render SMW-normalized UTC times in the workshop's local timezone.

Why pure integer arithmetic on hours and minutes:

PHP's strtotime doesn't reliably parse "HH:MM +N minutes" across

 versions, so chained relative-time additions are flaky.

Error: Invalid time. formats in the server's

 timezone, so a server in UTC and a server in PDT would render
 different output for the same input — silently broken.

Extracting H and i from the input via Error: Invalid time.

 and Error: Invalid time. is round-trip safe regardless of
 server TZ: parse and format both happen in the same zone.

Wraparound: adding 1440 (= 24 * 60) before mod 1440 ensures the result is non-negative for any reasonable offset (−24 < hours < 24). So 02:00 with offset −4 yields 22:00 cleanly without sign issues in #expr's mod operator.

Why this template wraps verbose math: the formula is computed three times (h, m, m-padding) and would otherwise be inlined in the row template, ballooning every session row. Factoring it out keeps the row template legible.

Parameters:

time — UTC time as HH:MM; pass-through

 unchanged when offset is empty

offset — hours from UTC (decimals OK for fractional

 zones like 5.75 for Nepal); empty/0 returns the input unchanged