two-horse-race/twohorserace

#!/usr/bin/env ruby

# All modules must be in the standard library. No third-party gems.
require 'json'
require 'date'
require 'pp'

def date_format(d)
	d.strftime("%-d %B %Y")
end

def divider
	puts '-' * 80
end

def first_word(s)
	s.split(" ").first
end

def subhead(s)
	puts
	puts
	puts s
	puts '-' * s.length
end

# FIXME
# Need to be clear what the input and output of this function should be.
# We should return an array of hashes (sorted?) not an array of arrays.
# This is essentially a reduce function. Do it generically?
# https://riptutorial.com/ruby/example/3624/inject--reduce
# https://ruby-doc.org/core-3.1.2/Enumerable.html#method-i-reduce
# https://stackoverflow.com/questions/4453511/group-hashes-by-keys-and-sum-the-values
# Return party names and aggregate sum of votes for each party.
def votes_by_party(ary_of_candidate_hashes)
	#pp ary_of_candidate_hashes
	output = {}
	ary_of_candidate_hashes.each do |candidate|
		if output.key?(candidate['party'])
			output[candidate['party']] += candidate['votes']
		else
			output[candidate['party']] = candidate['votes']
		end
	end
	#pp output
	output
end

# Load JSON data
unless (param = ARGV.shift)
	abort "Usage: #{$0} [FILE] or #{$0} -- to read from STDIN."
end

if param == '--'
	# Read JSON data from STDIN
	json = ARGF.read
else
	# Load JSON from file
	json = File.read(param)
end

data = JSON.parse(json)

# Bodies
data['bodies'].each do |body|
	puts body['name']
	puts "Elections: %d" % body['elections'].size

	# Elections
	sorted_elections = body['elections'].sort_by { |h| h['date'] }.reverse
	sorted_elections.each do |election|
		puts
		divider
		puts election['name'].upcase
		puts date_format(Date.parse(election['date']))
		puts election['reason'] if election['reason']
		puts "%d seats were elected in %d %s." % [ election['seats'],
		election['districts'], body['district_name_plural'] ]
		divider

		# Polls
		sorted_polls = election['polls'].sort_by { |h| h['district'] }
		sorted_polls.each do |poll|
			puts
			puts poll['district'].upcase
			puts

			# Candidates
			sorted_candidates = poll['candidates'].sort_by { |h| h['votes'] }.reverse
			sorted_candidates.each do |candidate|
				percentage = candidate['votes'].to_f / poll['votes'] * 100.0 * 
				poll['seats']
				candidate['elected'] ? elected = "elected" : ""
				puts "%-31s %-30s %5d %2d%% %s" % [
				first_word(candidate['forenames']) + ' ' + candidate['surname'],
				candidate['party'], candidate['votes'], percentage, elected ]
			end

			# Total votes in this poll
			if poll['votes']
				puts "%68s" % [ "=" * poll['votes'].to_s.size ]
				puts "%68d" % poll['votes']
			end

			# Rejected ballots in this poll
			if poll['rejected']
				puts
				puts "Rejected ballots: %d" % poll['rejected']
			end

			# Votes by party
			# Omit for single-seat polls as meaningless there.
			unless poll["seats"] == 1
				subhead("Votes by party")
				vbp = votes_by_party(poll['candidates'])
				# Sort array of arrays by the value in element [1], descending
				sorted_vbp = vbp.sort { |a,b| b[1] <=> a[1] }
				#pp sorted_vbp
				sorted_vbp.each do |party|
					puts "%-30s %5d %2d%%" % [ party[0], party[1], party[1].to_f /
					poll["votes"] * 100.0 ]
				end
			end

			# Sources
			if poll["sources"]
				subhead("Sources")
				poll["sources"].each { |source| puts source }
			end

			puts
			divider
		end
		divider
	end
end