#!/usr/bin/env ruby
# Inspired by https://github.com/olivierverdier/zsh-git-prompt
# [commit: 350be32093d0585f395413253536d891c247f538,
#  last commit checked: 0a6c8b610e799040b612db8888945f502a2ddd9d (2016-02-14)]
#Inspired by the contrib git script

require "open3"
require "pathname"
require "shellwords"
require "optparse"
require "simplecolor"
#require "dr/git" #TODO merge the two implems
SimpleColor.mix_in_string

module GitStatus
	module Run
		extend(self)
		#if we get interrupted once, we don't want to launch any more commands
		@interrupted=false
		def runstatus(*args)
			if !@interrupted
				begin
					if Open3.respond_to?(:capture3) then
						out, error, status=Open3.capture3(*args)
						return out, status.success?
					else
						out = `#{args} 2>/dev/null`
						status=$?
						return out, status.success?
					end
				rescue Interrupt #interruption
					@interrupted=true
					return "", false
				end
			else
				return "", false
			end
		end
		def run(*args)
			msg,_=runstatus(*args)
			return msg
		end
	end

	class Git
		include GitStatus::Run
		attr_reader :msg

		def git?
			if @git.nil?
				_,@git=runstatus "git rev-parse"
			end
			return @git
		end
		def getgitdir
			return Pathname.new((run "git rev-parse --git-dir").chomp)
		end
		def ingitdir?
			return (run "git rev-parse --is-inside-git-dir") == "true\n"
		end
		def worktree?
			return (run "git rev-parse --is-inside-work-tree") == "true\n"
		end
		def bare?
			return (run "git rev-parse --is-bare-repository") == "true\n"
		end

		def cd_and_exec(*args)
			if @path.nil? then
				yield(*args)
			else
				if File.directory?(@path)
					Dir.chdir(@path) do
						yield(*args)
					end
				else
					warn "#{@path} is not a directory"
				end
			end
		end

		def initialize(path=nil)
			#a nil path means we want information on the current directory
			if !path.nil?
				@path=Pathname.new(path).expand_path
			end
			cd_and_exec {git?}
		end

		def get_msg
			#gitst="git status --porcelain --branch"
			#too many git are too old to mix --porcelain with --branch
			gitm=git="git"
			gitm="#{git} -c color.ui=always" if $opts[:color]
			gitm="#{gitm} status --short --branch"
			@msg=run(gitm)
		end

		def describe_detached_head
			case $opts[:describe]
			when "sha1"
				describe=(run "git rev-parse --short HEAD").chomp
			when "describe"
				describe=(run "git describe HEAD").chomp
			when "contains"
				describe=(run "git describe --contains HEAD").chomp
			when "branch"
				describe=(run "git describe --contains --all HEAD").chomp
			when "match"
				describe=(run "git describe --tags --exact-match HEAD").chomp
			when "all" #try --contains all, then --all
				describe=(run "git describe --contains --all HEAD").chomp
				describe=(run "git describe --all HEAD").chomp if describe.nil? or describe.empty?
			when "magic"
				describe1=(run "git describe --contains --all HEAD").chomp
				describe2=(run "git describe --all HEAD").chomp
				describe= describe1.length < describe2.length ? describe1 : describe2
				describe=describe1 if describe2.empty?
				describe=describe2 if describe1.empty?
			else
				describe=(run($opts[:describe])).chomp
			end
			if describe.empty?
				describe=(run "git rev-parse --short HEAD").chomp
			end
			@branch=":#{describe}"
		end

		def parse_head(head)
			@ahead=@behind=0
			if (head =~ /## Initial commit on (\S*)/) then
			 @branch=$1
			 if @branch =~ /(\S*)\.\.\./
				 @branch=$1
			 end
			 @branch+="…"
			elsif (head =~ /## (\S*) \(no branch\)/) then
				describe_detached_head
			elsif (head =~ /## (\S*)(.*)/) then
				branchs=$1
				rest=$2
				if (branchs =~ /(\S*)\.\.\.(\S*)/) then
					@branch=$1
					remote=$2
				else
					@branch=branchs
				end
				if (rest =~ /.*\[ahead\s+(\d*)(.*)/) then
					@ahead=$1.to_i
					rest=$2
				end
				if (rest =~ /.*behind\s+(\d*)\]/) then
					@behind=$1.to_i
				end
			end
		end

		def parse_msg
			msg=@msg
			#find the branch name, and if we are behind/ahead of upstream
			lines=msg.uncolor.lines.to_a
			return if lines.empty?
			head=lines.shift
			parse_head(head)

			#get status of files
			@changed=@staged=@untracked=@conflicts=0
			lines.each do |line|
				index = line[0];
				workdir = line[1];
				#puts "index: #{index}, workdir: #{workdir}"
				if index=~/[DRAMTC]/ then
					@staged+=1
				end
				if workdir=~ /[DMT]/ then
					@changed+=1
				end
				if workdir=='?' || index=='?' then
					@untracked+=1
				end
				if workdir=='U' || index=='U' then
					@conflicts+=1
				end
			end
			@clean=true
			@clean=false if @staged != 0 || @changed !=0 ||
											@untracked !=0 || @conflicts !=0
		end

		def get_status
			if worktree?
				get_msg
				parse_msg
				if $opts[:sequencer] and !@msg.empty?
					@sequencer=""
					gitdir=getgitdir
					if (gitdir+"rebase-merge").directory?
						if (gitdir+"rebase-merge/interactive").file?
							@sequencer<<" rb-i " #REBASE-i
						else
							@sequencer<<" rb-m " #REBASE-m
						end
						@sequencer<<(gitdir+"rebase-merge/head-name").read.chomp.sub(/^refs\/heads\//,"")
					end
					if (gitdir+"rebase-apply").directory?
						if (gitdir+"rebase-apply/rebasing").file?
							@sequencer<<" rb" #RB
						elsif (gitdir+"rebase-apply/applying").file?
							@sequencer<<" am" #AM
						else
							@sequencer<<" am/rb" #AM/REBASE
						end
					end
					if (gitdir+"MERGE_HEAD").file?
						@sequencer<<" mg" #MERGING
					end
					if (gitdir+"CHERRY_PICK_HEAD").file?
						@sequencer<<" ch" #CHERRY-PICKING
					end
					if (gitdir+"BISECT_LOG").file?
						@sequencer<<" bi" #BISECTING
					end
					_,stashstatus=runstatus "git rev-parse --verify refs/stash"
					if stashstatus
						stashs=run "git rev-list -g refs/stash"
						@sequencer<<" $#{stashs.lines.to_a.length}" #Stash
					end
				end
				return !@msg.empty?
			else
				if $opts[:sequencer]
					if ingitdir?
						if bare?
							@branch="|bare|"
						else
							@branch="|.git|"
						end
					end
				end
			end
			return false
		end

		def status
			cd_and_exec { get_status } if git?
		end

		def prompt
			if status
				return "(" <<
				 @branch.color(:magenta,:bold) <<
				(@ahead==0 ? "" : "↑"<<@ahead.to_s ) <<
				(@behind==0 ? "" : "↓"<<@behind.to_s ) <<
				"|" <<
				(@staged==0 ? "" : ("●"+@staged.to_s).color(:red) ) <<
				(@conflicts==0 ? "" : ("✖"+@conflicts.to_s).color(:red) ) <<
				(@changed==0 ? "" : ("✚"+@changed.to_s).color(:blue) ) <<
				(@untracked==0 ? "" : "…" ) <<
				(@clean ? "✔".color(:green,:bold) : "" ) <<
				(@sequencer.empty? ? "" : @sequencer.color(:yellow) ) <<
				")"
			else
				return "(" << @branch.color(:magenta,:bold) << ")" if @branch
			end
		end

		def porcelain
			if git?
				return "#{@branch}\n#{@ahead}\n#{@behind}\n#{@staged}\n#{@conflicts}\n#{@changed}\n#{@untracked}\n#{@clean?1:0}\n#{@sequencer}\n"
			else
				return ""
			end
		end
	end
end

$opts={:color => true, :indent => nil, :sequencer => true, :describe => "magic"}
optparse = OptionParser.new do |opt|
	opt.banner= "#{File.basename($0)} [options] git_dirs"
	opt.on("-p", "--[no-]prompt", "To be used in shell prompt", "This ensure that color ansi sequence are escaped so that they are not counted as text by the shell") do |v|
		$opts[:prompt]=v
	end
	opt.on("--[no-]porcelain", "Don't format the status but output it in a machine convenient format") do |v|
		$opts[:porcelain]=v
	end
	opt.on("-s", "--[no-]status", "List file", "Print the output of git status additionally of what this program parse") do |v|
		$opts[:status]=v
	end
	opt.on("-c", "--[no-]color", "Color output", "on by default") do |v|
		$opts[:color]=v
	end
	opt.on("--[no-]sequencer", "Show sequencer data (and also look for bare directory)", "on by default") do |v|
		$opts[:sequencer]=v
	end
	opt.on("--indent spaces", Integer, "Indent to use if showing git status", "2 by default, 0 for empty ARGV") do |v|
		$opts[:indent]=v
	end
	opt.on("--describe sha1/describe/contains/branch/match/all/magic", "How to describe a detached HEAD", "'magic' by default") do |v|
		$opts[:describe]=v
	end
	opt.on("--sm", "Recurse on each submodules") do |v|
		$opts[:submodules]=v
	end
end
optparse.parse!

if !$opts[:color]
	SimpleColor.enabled=false
end

def prettify_dir(dir)
	return dir.sub(/^#{ENV['HOME']}/,"~")
end

def gs_output(dir)
	g=GitStatus::Git.new(dir)
	puts "#{prettify_dir(dir)+": " if dir}#{g.prompt}"
	if $opts[:status] and g.git?
		g.msg.lines.each do |line|
			print " "*$opts[:indent] + line
		end
	end
end

if $opts[:porcelain]
	puts GitStatus::Git.new.porcelain
elsif $opts[:prompt]
	SimpleColor.enabled=:shell
	prompt=GitStatus::Git.new.prompt
	puts prompt if prompt #in ruby1.8, puts nil output nil...
else
	args=ARGV
	if args.empty?
		$opts[:indent]=0 unless $opts[:indent]
		args=[nil]
	else
		$opts[:indent]=2 unless $opts[:indent]
	end
	args.each do |dir|
		gs_output(dir)
		if $opts[:submodules]
			Dir.chdir(dir||".") do
				%x/git submodule status/.each_line.map { |l| l.split[1] }.each do |dir|
					gs_output(dir)
				end
			end
		end
	end
end