module GitHelpers
	
	module GitStats
		#Note: stats-authors give the same result, should be faster, and handle mailcap
		#inspired by git-mainline//git-rank-contributors
		def stats_diff(logopts=nil)
			lines = {}

			with_dir do
				author = nil
				state = :pre_author
				DR::Encoding.fix_utf8(`git log #{DefaultLogOptions} -p #{logopts}`).each_line do |l|
					case
					when (state == :pre_author || state == :post_author) && m=l[/Author: (.*)$/,1]
						#TODO: using directly author=l[]... seems to only affect a block scoped author variable
						author=m
						state = :post_author
						lines[author] ||= {added: 0, deleted: 0, all: 0}
					when state == :post_author && l =~ /^\+\+\+\s/
						state = :in_diff
					when state == :in_diff && l =~ /^[\+\-]/
						unless l=~ /^(\+\+\+|\-\-\-)\s/
							lines[author][:all] += 1 
							lines[author][:added] += 1	if l[0]=="+"
							lines[author][:deleted] += 1 if l[0]=="-"
						end
					when state == :in_diff && l =~ /^commit /
						state = :pre_author
					end
				end
			end
			lines
		end

		def output_stats_diff(logopts=nil)
			lines=stats_diff(logopts)
			lines.sort_by { |a, c| -c[:all] }.each do |a, c|
				puts "#{a}: #{c[:all]} lines of diff (+#{c[:added]}/-#{c[:deleted]})"
			end
		end

		# inspired by visionmedia//git-line-summary
		def stats_lines(file)
			out=""
			with_dir do
				out,_suc=SH.run_simple("git", "blame", "--line-porcelain", file, quiet: true)
			end
			r={}
			begin
			out.each_line do |l|
					l.match(/^author (.*)/) do |m|
						r[m[1]]||=0
						r[m[1]]+=1
					end
				end
			rescue => e
				warn "Warning: #{e} on #{file}"
			end
			r
		end

		def stats_lines_all
			r={}
			all_files.select {|f| SH::Pathname.new(f).text? rescue false}.each do |f|
				stats_lines(f).each do |k,v|
					r[k]||=0
					r[k]+=v
				end
			end
			r
		end

		def output_stats_lines
			stats=stats_lines_all
			total=stats.values.sum
			stats.sort_by{|k,v| -v}.each do |k,v|
				puts "- #{k}: #{v} (#{"%2.1f%%" % (100*v/total.to_f)})"
			end
			puts "Total lines: #{total}"
		end

		#Inspired by https://github.com/esc/git-stats/blob/master/git-stats.sh
		def stats_authors(logopts=nil, more: false)
			require 'set'
			#Exemple: --after=..., --before=...,
			#  -w #word diff
			#  -C --find-copies-harder; -M
			authors={}
			with_dir do
				%x/git shortlog -sn #{logopts}/.each_line do |l|
					commits, author=l.chomp.split(' ', 2)
					authors[author]={commits: commits.to_i}
				end

				if more
					authors.each_key do |a|
						tot_a=0; tot_r=0; tot_rename=0; files=Set.new
						%x/git log #{DefaultLogOptions} #{logopts} --numstat --format="%n" --author='#{a}'/.each_line do |l|
							added, deleted, file=l.chomp.split(' ',3)
							#puts "#{l} => #{added}, #{deleted}, #{rest}"
							tot_a+=added.to_i; tot_r+=deleted.to_i
							next if file.nil?
							if file.include?(' => ')
								tot_rename+=1
							else
								files.add(file) unless file.empty?
							end
						end
						#rev-list should be faster, but I would need to use 
						# `git rev-parse --revs-only --default HEAD #{logopts.shelljoin}`
						# to be sure we default to HEAD, and 
						# `git rev-parse --flags #{logopts.shelljoin}` to get the log flags...
						#tot_merges=%x/git rev-list #{logopts} --merges --author='#{a}'/.each_line.count
						tot_merges=%x/git log --pretty=oneline #{logopts} --merges --author='#{a}'/.each_line.count
						authors[a].merge!({added: tot_a, deleted: tot_r, files: files.size, renames: tot_rename, merges: tot_merges})
					end
				end
			end
			authors
		end

		def output_stats_authors(logopts=nil)
			authors=stats_authors(logopts, more: true)
			authors.each do |a,v|
				puts "- #{a}: #{v[:commits]} commits (+#{v[:added]}/-#{v[:deleted]}), #{v[:files]} files modified, #{v[:renames]} renames, #{v[:merges]} merges"
			end
		end

		#inspired by visionmedia//git-infos
		def infos
			with_dir do
				puts "## Remote URLs:"
				puts
				system("git --no-pager remote -v")
				puts
				
				puts "## Remote Branches:"
				puts
				system("git --no-pager  branch -r")
				puts
				
				puts "## Local Branches:"
				puts
				system("git --no-pager  branch")
				puts
				
				puts "## Most Recent Commit:"
				puts
				system("git --no-pager log --max-count=1 --pretty=short")
				puts
			end
		end

		#inspired by visionmedia//git-summary
		def summary(logopts=nil)
			with_dir do
				project=Pathname.new(%x/git rev-parse --show-toplevel/).basename
				authors=stats_authors(logopts)
				commits=authors.map {|a,v| v[:commits]}.sum
				file_count=%x/git ls-files/.each_line.count
				active_days=%x/git log --date=short --pretty='format: %ad' #{logopts}/.each_line.uniq.count
				#This only give the rep age of the current branch; and is not
				#efficient since we generate the first log
				#A better way would be to get all the roots commits via
				#    git rev-list --max-parents=0 HEAD
				#and then look at their ages
				repository_age=%x/git log --reverse --pretty=oneline --format="%ar" #{logopts}/.each_line.first.sub!('ago','')
				#total= %x/git rev-list #{logopts}/.each_line.count
				total=%x/git rev-list --count #{logopts.empty? ? "HEAD" : logopts.shelljoin}/.to_i

				puts " project  : #{project}"
				puts " repo age : #{repository_age}"
				puts " active   : #{active_days} days"
				puts " commits  : #{commits}"
				puts " files    : #{file_count}"
				puts " authors  : #{authors.keys.join(", ")} (Total: #{total})"
				authors.each do |a,v|
					puts " - #{a}: #{v[:commits]} (#{"%2.1f" % (100*v[:commits]/commits.to_f)}%)"
				end
			end
		end
	end
end