class Covered::Files::State

def self.for(path, **options)
	self.new(Source.new(path, **options))
end

def [](lineno)
	@counts[lineno]
end

def annotate(lineno, annotation)
	@annotations[lineno] ||= []
	@annotations[lineno] << annotation
end

def coverage
	Coverage.new(@source, @counts, @annotations)
end

def initialize(source)
	@source = source
	@counts = []
	@annotations = {}
end

def mark(lineno, value = 1)
	# As currently implemented, @counts is base-zero rather than base-one.
	# Line numbers generally start at line 1, so the first line, line 1, is at index 1. This means that index[0] is usually nil.
	Array(value).each_with_index do |value, index|
		offset = lineno + index
		if @counts[offset]
			@counts[offset] += value
		else
			@counts[offset] = value
		end
	end
end

def merge!(coverage)
	coverage.counts.each_with_index do |count, index|
		if count
			@counts[index] ||= 0
			@counts[index] += count
		end
	end
	
	@annotations.merge!(coverage.annotations) do |lineno, a, b|
		Array(a) + Array(b)
	end
end