47 lines
1.6 KiB
Ruby
47 lines
1.6 KiB
Ruby
# frozen_string_literal: true
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module Jekyll
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module Utils
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module WinTZ
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extend self
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# Public: Calculate the Timezone for Windows when the config file has a defined
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# 'timezone' key.
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#
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# timezone - the IANA Time Zone specified in "_config.yml"
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#
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# Returns a string that ultimately re-defines ENV["TZ"] in Windows
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def calculate(timezone, now = Time.now)
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External.require_with_graceful_fail("tzinfo") unless defined?(TZInfo)
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tz = TZInfo::Timezone.get(timezone)
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#
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# Use period_for_utc and utc_total_offset instead of
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# period_for and observed_utc_offset for compatibility with tzinfo v1.
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offset = tz.period_for_utc(now.getutc).utc_total_offset
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#
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# POSIX style definition reverses the offset sign.
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# e.g. Eastern Standard Time (EST) that is 5Hrs. to the 'west' of Prime Meridian
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# is denoted as:
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# EST+5 (or) EST+05:00
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# Reference: https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html
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sign = offset.positive? ? "-" : "+"
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rational_hours = offset.abs.to_r / 3600
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hours = rational_hours.to_i
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minutes = ((rational_hours - hours) * 60).to_i
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#
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# Format the hours and minutes as two-digit numbers.
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time = format("%<hours>02d:%<minutes>02d", :hours => hours, :minutes => minutes)
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Jekyll.logger.debug "Timezone:", "#{timezone} #{sign}#{time}"
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#
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# Note: The 3-letter-word below doesn't have a particular significance.
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"WTZ#{sign}#{time}"
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end
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end
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end
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end
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