Implement basic support for progress bar output.

lib/console/logger.rb

@@ -19,6 +19,7 @@
 # THE SOFTWARE.
 
 require_relative 'filter'
+require_relative 'measure'
 
 module Console
 	class Logger < Filter[debug: 0, info: 1, warn: 2, error: 3, fatal: 4]
@@ -27,5 +28,9 @@ class Logger < Filter[debug: 0, info: 1, warn: 2, error: 3, fatal: 4]
 		def initialize(output, **options)
 			super(output, **options)
 		end
+
+		def measure(subject, total)
+			Measure.new(self, subject, total)
+		end
 	end
 end

lib/console/measure.rb

@@ -0,0 +1,127 @@
+# Copyright, 2019, by Samuel G. D. Williams. <http://www.codeotaku.com>
+# 
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+# 
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+# 
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+module Console
+	class Measure
+		module Bar
+			BLOCK = [
+				" ",
+				"▏",
+				"▎",
+				"▍",
+				"▌",
+				"▋",
+				"▊",
+				"▉",
+				"█",
+			]
+
+			def self.format(value, width)
+				blocks = width * value
+				full_blocks = blocks.floor
+				partial_block = ((blocks - full_blocks) * BLOCK.size).floor
+
+				if partial_block.zero?
+					BLOCK.last * full_blocks
+				else
+					"#{BLOCK.last * full_blocks}#{BLOCK[partial_block]}"
+				end.ljust(width)
+			end
+		end
+
+		def initialize(output, subject, total = 0)
+			@output = output
+			@subject = subject
+
+			@start_time = Time.now
+
+			@current = 0
+			@total = total
+		end
+
+		def duration
+			Time.now - @start_time
+		end
+
+		def remaining
+			@total - @current
+		end
+
+		def average_duration
+			if @current > 0
+				duration / @current
+			end
+		end
+
+		def estimated_remaining_time
+			if average_duration = self.average_duration
+				average_duration * remaining
+			end
+		end
+
+		def increment(amount = 1)
+			@current += amount
+
+			@output.info(@subject, self) {self.formatted_progress_bar}
+
+			return self
+		end
+
+		def mark(*arguments)
+			@output.info(@subject, *arguments) {self.formatted_progress_bar}
+		end
+
+		def formatted_progress_bar(width = 70)
+			"[#{Bar.format(@current.to_f / @total.to_f, width)}]"
+		end
+
+		def to_s
+			if estimated_remaining_time = self.estimated_remaining_time
+				"#{@current}/#{@total} completed, #{self.formatted_duration estimated_remaining_time} remaining."
+			else
+				"#{@current}/#{@total} completed, waiting for estimate..."
+			end
+		end
+
+		private
+
+		def formatted_duration(duration)
+			if duration < 60.0
+				return "#{duration.round(2)}s"
+			end
+
+			duration /= 60.0
+
+			if duration < 60.0
+				return "#{duration.round}m"
+			end
+
+			duration /= 60.0
+
+			if duration < 60.0
+				return "#{duration.round(1)}h"
+			end
+
+			duration /= 24.0
+
+			return "#{duration.round(1)}d"
+		end
+	end
+end