# vim: set noet sw=2 ts=2 sts=2:

require 'json'
require 'socket'

class JSONLIO <IO
	include Enumerable
	extend Enumerable
	def orig_io() @io end
	def to_io() self end
	def to_i() @io.to_i end
	def fileno() @io.fileno end
	def unpacker() @un end
	def close() @io.close end
	def close_write() @io.close_write end
	def close_read() @io.close_read end
	def write( obj) @io.write obj.to_json+"\n" end
	def sync() @io.sync end
	def sync=( v) @io.sync = v end
	def inspect() "#<#{self.class.name} fd:#{@io.to_i} #{@mode}>" end
	def initialize( io) @io = io end

	class <<self
		def stream() Socket.pair( :UNIX, :STREAM, 0).map {|s| self.new s, :rw } end

		def pipe
			a, b = IO.pipe
			[self.new( a, :r), self.new( b, :w)]
		end

		def popen mode = nil, &exe
			s1, s2 =
				case mode
				when :rw, 'rw', nil then self.stream
				when :r, 'r' then self.pipe
				when :w, 'w' then self.pipe.reverse
				end
			pid =
				fork do
					s1.close
					yield s2
					exit 0
				end
			s2.close
			[pid, s1]
		end

		def open io, mode = :r, &exe
			s = self.new io, mode
			if block_given?
				begin yield s
				ensure s.close
				end
			else s
			end
		end

		def each fn, &exe
			open fn, 'r' do |f|
				f.each &exe
			end
		end
	end

	attr_reader :lineno

	def initialize io, mode = :rw
		case io
		when IO then @io = io
		when String then @io = File.open io, mode
		when Pathname then @io = io.open mode
		else raise ArgumentError, "This seems not to be a IO/String/Pathname: #{io.inspect}"
		end
		@lineno, @mode, @io.sync = 0, mode, true
	end

	def read
		JSON.parse( @io.readline.chomp).tap { @lineno += 1 }
	rescue Exception
		raise $!.class, $!.message + " (JSONL-line: #{@lineno})", $!.backtrace
	end

	def each &exe
		return to_enum __method__  unless block_given?
		loop { yield read }
		self
	rescue EOFError
		self
	end
end