From 189e4306f324ea2328281ee2f28642f7c3abc95f Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Wed, 20 Apr 2016 19:45:33 -0400
Subject: [PATCH 01/15] Ruby ls clone v0

Basic tests passing. Project structure taking form. Thinking of refactoring the
permissions implementation.
---
 samples/part1/bin/ruby-ls            |  5 ++-
 samples/part1/lib/rls.rb             |  6 +++
 samples/part1/lib/rls/application.rb | 35 ++++++++++++++++
 samples/part1/lib/rls/display.rb     | 61 ++++++++++++++++++++++++++++
 samples/part1/lib/rls/long_format.rb | 59 +++++++++++++++++++++++++++
 samples/part1/lib/rls/permissions.rb | 31 ++++++++++++++
 samples/part1/ls_tests.rb            |  6 +--
 7 files changed, 198 insertions(+), 5 deletions(-)
 create mode 100644 samples/part1/lib/rls.rb
 create mode 100644 samples/part1/lib/rls/application.rb
 create mode 100644 samples/part1/lib/rls/display.rb
 create mode 100644 samples/part1/lib/rls/long_format.rb
 create mode 100644 samples/part1/lib/rls/permissions.rb

diff --git a/samples/part1/bin/ruby-ls b/samples/part1/bin/ruby-ls
index f10c79a..b2ea1cf 100755
--- a/samples/part1/bin/ruby-ls
+++ b/samples/part1/bin/ruby-ls
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
 
-## FIXME: Replace this code with a pure Ruby clone of the ls utility
-system("ls", *ARGV)
+require_relative '../lib/rls'
+
+RLs::Application.new(ARGV).run
diff --git a/samples/part1/lib/rls.rb b/samples/part1/lib/rls.rb
new file mode 100644
index 0000000..11b456c
--- /dev/null
+++ b/samples/part1/lib/rls.rb
@@ -0,0 +1,6 @@
+require 'optparse'
+
+require_relative 'rls/application'
+require_relative 'rls/display'
+require_relative 'rls/long_format'
+require_relative 'rls/permissions'
diff --git a/samples/part1/lib/rls/application.rb b/samples/part1/lib/rls/application.rb
new file mode 100644
index 0000000..bfcc306
--- /dev/null
+++ b/samples/part1/lib/rls/application.rb
@@ -0,0 +1,35 @@
+module RLs
+  class Application
+    def initialize(argv)
+      @options, @paths = parse_options(argv)
+      @display = RLs::Display.new(@options)
+    end
+
+    def run
+      paths.any? ? list_paths : list_current_directory
+    end
+
+    private
+
+    attr_reader :paths, :display
+
+    def parse_options(argv)
+      options = {}
+      parser = OptionParser.new do |p|
+        p.on('-l') { options[:long_format]    = true }
+        p.on('-a') { options[:include_hidden] = true }
+      end
+      paths = parser.parse(argv)
+
+      [options, paths]
+    end
+
+    def list_current_directory
+      display.render(Dir.pwd)
+    end
+
+    def list_paths
+      paths.each { |path| display.render(path) }
+    end
+  end
+end
diff --git a/samples/part1/lib/rls/display.rb b/samples/part1/lib/rls/display.rb
new file mode 100644
index 0000000..7092e5e
--- /dev/null
+++ b/samples/part1/lib/rls/display.rb
@@ -0,0 +1,61 @@
+module RLs
+  class Display
+    def initialize(options)
+      @long_format = options[:long_format]
+    end
+
+    def render(path)
+      if Dir.exist?(path)
+        render_directory(path)
+      else
+        list_if_visible(path)
+      end
+    end
+
+    private
+
+    attr_reader :long_format
+
+    def render_directory(dirname)
+      list_total_blocks(dirname) if long_format
+      Dir.foreach(dirname) { |e| list_if_visible(e) }
+    end
+
+    def list_total_blocks(dirname)
+      puts "total #{total_blocks(dirname)}"
+    end
+
+    def total_blocks(dirname)
+      entries = Dir.entries(dirname).reject { |e| hidden?(e) }
+
+      entries.reduce(0) do |sum, e|
+        path = File.join(dirname, e)
+        sum + blocks_allocated(path)
+      end
+    end
+
+    def blocks_allocated(path)
+      File.stat(path).blocks
+    end
+
+    def list_if_visible(filename)
+      list(filename) if ! hidden?(filename)
+    end
+
+    def hidden?(filename)
+      filename[0] == '.'
+    end
+
+    def list(filename)
+      puts formatted(filename)
+    end
+
+    def formatted(filename)
+      if long_format
+        File.open(filename) { |f| RLs::LongFormat.new(f) }
+      else
+        filename
+      end
+    end
+  end
+end
diff --git a/samples/part1/lib/rls/long_format.rb b/samples/part1/lib/rls/long_format.rb
new file mode 100644
index 0000000..b40fa6c
--- /dev/null
+++ b/samples/part1/lib/rls/long_format.rb
@@ -0,0 +1,59 @@
+module RLs
+  class LongFormat
+    FTYPES = {
+      'blockSpecial'     => 'b',
+      'characterSpecial' => 'c',
+      'directory'        => 'd',
+      'link'             => 'l',
+      'socket'           => 's',
+      'fifo'             => 'P',
+      'file'             => '-'
+    }
+
+    def initialize(file)
+      @file        = file
+      @stat        = File.stat(@file)
+      @permissions = RLs::Permissions.new(@stat)
+    end
+
+    def to_s
+      "#{mode} #{links} #{owner}  #{group} #{bytes} #{last_modified} #{path}"
+    end
+
+    private
+
+    attr_reader :file, :stat, :permissions
+
+    def mode
+      ftype = FTYPES[stat.ftype]
+      "#{ftype}#{permissions}"
+    end
+
+    def links
+      nlink = stat.nlink
+      nlink.to_s.rjust(2)
+    end
+
+    def owner
+      `id -un #{stat.uid}`.chomp
+    end
+
+    def group
+      `id -gn #{stat.uid}`.chomp
+    end
+
+    def bytes
+      size = stat.size
+      size.to_s.rjust(4)
+    end
+
+    def last_modified
+      time = stat.mtime
+      time.strftime('%b %e %H:%M')
+    end
+
+    def path
+      file.path
+    end
+  end
+end
diff --git a/samples/part1/lib/rls/permissions.rb b/samples/part1/lib/rls/permissions.rb
new file mode 100644
index 0000000..924ed48
--- /dev/null
+++ b/samples/part1/lib/rls/permissions.rb
@@ -0,0 +1,31 @@
+module RLs
+  class Permissions
+    def initialize(file_stat)
+      @fmode = file_stat.mode
+    end
+
+    def to_s
+      fm = @fmode
+
+      world = fm % 8
+      fm /= 8
+      group = fm % 8
+      fm /= 8
+      owner = fm % 8
+
+      [owner, group, world].map { |bits| read_write_execute(bits) }.join
+    end
+
+    private
+
+    def read_write_execute(bits)
+      x = (bits % 2) > 0 ? 'x' : '-'
+      bits /= 2
+      w = (bits % 2) > 0 ? 'w' : '-'
+      bits /= 2
+      r = (bits % 2) > 0 ? 'r' : '-'
+
+      "#{r}#{w}#{x}"
+    end
+  end
+end
diff --git a/samples/part1/ls_tests.rb b/samples/part1/ls_tests.rb
index 4371b25..9e4e1a8 100644
--- a/samples/part1/ls_tests.rb
+++ b/samples/part1/ls_tests.rb
@@ -7,11 +7,11 @@
 
 # TODO: Uncomment each test below and get it to pass.
 
-# check("Dir listing", "foo")
+check("Dir listing", "foo")
 
-# check("File glob", "foo/*.txt")
+check("File glob", "foo/*.txt")
 
-# check("Detailed output", "-l")
+check("Detailed output", "-l")
 
 # check("Hidden files", "-a")
 

From 40956ecc874b7387247f8adde361b159dc18b3e3 Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Thu, 21 Apr 2016 01:00:29 -0400
Subject: [PATCH 02/15] it's alive

interesting evolution of Permissions class. Next step is eliminating duplication between
the #component_fields and #permitted_operations methods.
---
 samples/part1/lib/rls/permissions.rb | 48 +++++++++++++++++++---------
 1 file changed, 33 insertions(+), 15 deletions(-)

diff --git a/samples/part1/lib/rls/permissions.rb b/samples/part1/lib/rls/permissions.rb
index 924ed48..c3ee5dc 100644
--- a/samples/part1/lib/rls/permissions.rb
+++ b/samples/part1/lib/rls/permissions.rb
@@ -1,31 +1,49 @@
 module RLs
   class Permissions
+    COMPONENTS = [:owner, :group, :world]
+    OPERATIONS = [:r, :w, :x]
+    DASH = '-'.freeze
+
     def initialize(file_stat)
       @fmode = file_stat.mode
     end
 
     def to_s
-      fm = @fmode
+      rwx = component_fields.map do |field|
+        permitted_operations(field)
+      end
+      rwx.join
+    end
+
+    private
 
-      world = fm % 8
-      fm /= 8
-      group = fm % 8
-      fm /= 8
-      owner = fm % 8
+    def component_fields
+      max_component_index = COMPONENTS.count - 1
+      bits_per_component = OPERATIONS.count
+      operation_combos = 2 ** bits_per_component
 
-      [owner, group, world].map { |bits| read_write_execute(bits) }.join
+      COMPONENTS.each_with_index.map do |component, i|
+        lesser_components = max_component_index - i
+        bit_offset = lesser_components * bits_per_component
+
+        (@fmode >> bit_offset) % operation_combos
+      end
     end
 
-    private
+    def permitted_operations(field)
+      max_operation_index = OPERATIONS.count - 1
+      bits_per_operation = 1
+      cardinality = 2 ** bits_per_operation
+
+      bits = OPERATIONS.each_with_index.map do |symbol, index|
+        lesser_operations = max_operation_index - index
+        bit_offset = lesser_operations * bits_per_operation
 
-    def read_write_execute(bits)
-      x = (bits % 2) > 0 ? 'x' : '-'
-      bits /= 2
-      w = (bits % 2) > 0 ? 'w' : '-'
-      bits /= 2
-      r = (bits % 2) > 0 ? 'r' : '-'
+        bit = (field >> bit_offset) % cardinality
+        bit > 0 ? symbol : DASH
+      end
 
-      "#{r}#{w}#{x}"
+      bits.join
     end
   end
 end

From 731f1bdc3ca613ae71db8c6f2ffb0fe2786dec32 Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Thu, 21 Apr 2016 01:44:31 -0400
Subject: [PATCH 03/15] kinda cool, but is it better or worse?

---
 samples/part1/lib/rls/permissions.rb | 48 ++++++++++++++--------------
 1 file changed, 24 insertions(+), 24 deletions(-)

diff --git a/samples/part1/lib/rls/permissions.rb b/samples/part1/lib/rls/permissions.rb
index c3ee5dc..532978e 100644
--- a/samples/part1/lib/rls/permissions.rb
+++ b/samples/part1/lib/rls/permissions.rb
@@ -1,49 +1,49 @@
 module RLs
   class Permissions
-    COMPONENTS = [:owner, :group, :world]
+    FIELDS = [:owner, :group, :world]
     OPERATIONS = [:r, :w, :x]
-    DASH = '-'.freeze
+    MINUS = '-'.freeze
 
     def initialize(file_stat)
       @fmode = file_stat.mode
     end
 
     def to_s
-      rwx = component_fields.map do |field|
-        permitted_operations(field)
+      rwx = field_components.map do |bit_field|
+        permitted_operations(bit_field) do |bit, operation|
+          enabled?(bit) ? operation : MINUS
+        end
       end
+
       rwx.join
     end
 
     private
 
-    def component_fields
-      max_component_index = COMPONENTS.count - 1
-      bits_per_component = OPERATIONS.count
-      operation_combos = 2 ** bits_per_component
-
-      COMPONENTS.each_with_index.map do |component, i|
-        lesser_components = max_component_index - i
-        bit_offset = lesser_components * bits_per_component
+    def field_components
+      mode_components(@fmode, FIELDS, bits_per_component: OPERATIONS.count)
+    end
 
-        (@fmode >> bit_offset) % operation_combos
-      end
+    def permitted_operations(bit_field, &block)
+      mode_components(bit_field, OPERATIONS, bits_per_component: 1, &block)
     end
 
-    def permitted_operations(field)
-      max_operation_index = OPERATIONS.count - 1
-      bits_per_operation = 1
-      cardinality = 2 ** bits_per_operation
+    def mode_components(mode, components, bits_per_component:)
+      max_index = components.count - 1
+      cardinality = 2 ** bits_per_component
 
-      bits = OPERATIONS.each_with_index.map do |symbol, index|
-        lesser_operations = max_operation_index - index
-        bit_offset = lesser_operations * bits_per_operation
+      components.each_with_index.map do |component, index|
+        lesser_components = max_index - index
+        bit_offset = lesser_components * bits_per_component
 
-        bit = (field >> bit_offset) % cardinality
-        bit > 0 ? symbol : DASH
+        val = (mode >> bit_offset) % cardinality
+        val = yield(val, component) if block_given?
+        val
       end
+    end
 
-      bits.join
+    def enabled?(bit)
+      bit > 0
     end
   end
 end

From dda38f34afa0095390a5eb7531a51c87a350ec87 Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Fri, 6 May 2016 23:19:44 -0400
Subject: [PATCH 04/15] use bit masks for permissions

---
 samples/part1/lib/rls/permissions.rb | 41 ++++++++++------------------
 1 file changed, 14 insertions(+), 27 deletions(-)

diff --git a/samples/part1/lib/rls/permissions.rb b/samples/part1/lib/rls/permissions.rb
index 532978e..b58ca86 100644
--- a/samples/part1/lib/rls/permissions.rb
+++ b/samples/part1/lib/rls/permissions.rb
@@ -1,49 +1,36 @@
 module RLs
   class Permissions
-    FIELDS = [:owner, :group, :world]
+    ACTORS = [:owner, :group, :other]
     OPERATIONS = [:r, :w, :x]
-    MINUS = '-'.freeze
 
     def initialize(file_stat)
       @fmode = file_stat.mode
     end
 
     def to_s
-      rwx = field_components.map do |bit_field|
-        permitted_operations(bit_field) do |bit, operation|
-          enabled?(bit) ? operation : MINUS
-        end
-      end
-
-      rwx.join
+      symbols.join
     end
 
     private
 
-    def field_components
-      mode_components(@fmode, FIELDS, bits_per_component: OPERATIONS.count)
+    def symbols
+      bit_masks.map do |mask, operation|
+        enabled?(@fmode & mask) ? operation : :-
+      end
     end
 
-    def permitted_operations(bit_field, &block)
-      mode_components(bit_field, OPERATIONS, bits_per_component: 1, &block)
+    def bit_masks
+      msb_masks = lsb_masks.reverse
+      msb_masks.zip(OPERATIONS.cycle)
     end
 
-    def mode_components(mode, components, bits_per_component:)
-      max_index = components.count - 1
-      cardinality = 2 ** bits_per_component
-
-      components.each_with_index.map do |component, index|
-        lesser_components = max_index - index
-        bit_offset = lesser_components * bits_per_component
-
-        val = (mode >> bit_offset) % cardinality
-        val = yield(val, component) if block_given?
-        val
-      end
+    def lsb_masks
+      bits = (ACTORS.count * OPERATIONS.count)
+      bits.times.map { |offset| 0b1 << offset }
     end
 
-    def enabled?(bit)
-      bit > 0
+    def enabled?(bits)
+      bits > 0
     end
   end
 end

From a7fbe2f2acfe49b0ea906813c8abce729f074198 Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Fri, 6 May 2016 23:58:01 -0400
Subject: [PATCH 05/15] allow display of hidden files

---
 samples/part1/lib/rls/display.rb | 17 ++++++++++++-----
 samples/part1/ls_tests.rb        |  4 ++--
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/samples/part1/lib/rls/display.rb b/samples/part1/lib/rls/display.rb
index 7092e5e..de271e5 100644
--- a/samples/part1/lib/rls/display.rb
+++ b/samples/part1/lib/rls/display.rb
@@ -2,6 +2,7 @@ module RLs
   class Display
     def initialize(options)
       @long_format = options[:long_format]
+      @include_hidden = options[:include_hidden]
     end
 
     def render(path)
@@ -14,7 +15,7 @@ def render(path)
 
     private
 
-    attr_reader :long_format
+    attr_reader :long_format, :include_hidden
 
     def render_directory(dirname)
       list_total_blocks(dirname) if long_format
@@ -26,20 +27,26 @@ def list_total_blocks(dirname)
     end
 
     def total_blocks(dirname)
-      entries = Dir.entries(dirname).reject { |e| hidden?(e) }
-
-      entries.reduce(0) do |sum, e|
+      entries(dirname).reduce(0) do |sum, e|
         path = File.join(dirname, e)
         sum + blocks_allocated(path)
       end
     end
 
+    def entries(dirname)
+      Dir.entries(dirname).select { |e| show?(e) }
+    end
+
     def blocks_allocated(path)
       File.stat(path).blocks
     end
 
     def list_if_visible(filename)
-      list(filename) if ! hidden?(filename)
+      list(filename) if show?(filename)
+    end
+
+    def show?(filename)
+      include_hidden || !hidden?(filename)
     end
 
     def hidden?(filename)
diff --git a/samples/part1/ls_tests.rb b/samples/part1/ls_tests.rb
index 9e4e1a8..4392382 100644
--- a/samples/part1/ls_tests.rb
+++ b/samples/part1/ls_tests.rb
@@ -13,9 +13,9 @@
 
 check("Detailed output", "-l")
 
-# check("Hidden files", "-a")
+check("Hidden files", "-a")
 
-# check("Hidden files with detailed output", "-a -l")
+check("Hidden files with detailed output", "-a -l")
 
 # check("File glob with detailed output", "-l foo/*.txt")
 

From ece3e99b984750366f5c750e98cc0958c535c826 Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Sun, 8 May 2016 16:10:36 -0400
Subject: [PATCH 06/15] max-byte-counts, long-format, glob

In order to make the column line up, each entry needs to share some knowledge related to
the byte counts of other entries. I probably need to refactor this a bit and make clearer
distinctions between code that parses trees (figures out what files/directories will be
listed) and code that formats for display.
---
 samples/part1/lib/rls/application.rb | 38 +++++++++++++++++++---------
 samples/part1/lib/rls/display.rb     |  5 ++--
 samples/part1/lib/rls/long_format.rb | 12 +++++----
 samples/part1/ls_tests.rb            |  2 +-
 4 files changed, 37 insertions(+), 20 deletions(-)

diff --git a/samples/part1/lib/rls/application.rb b/samples/part1/lib/rls/application.rb
index bfcc306..f2e8973 100644
--- a/samples/part1/lib/rls/application.rb
+++ b/samples/part1/lib/rls/application.rb
@@ -1,17 +1,38 @@
 module RLs
   class Application
     def initialize(argv)
-      @options, @paths = parse_options(argv)
-      @display = RLs::Display.new(@options)
+      options, @paths = parse_options(argv)
+      options.merge!(max_byte_count: byte_counts.max)
+      @display = RLs::Display.new(options)
     end
 
     def run
-      paths.any? ? list_paths : list_current_directory
+      @paths.each { |p| @display.render(p) }
     end
 
     private
 
-    attr_reader :paths, :display
+    def byte_counts
+      @paths.flat_map do |p|
+        Dir.exist?(p) ? directory_byte_counts(p) : byte_count(p)
+      end
+    end
+
+    def directory_byte_counts(path)
+      directory_subpaths(path).map { |p| byte_count(p) }
+    end
+
+    def directory_subpaths(path)
+      non_dot_char = /[^\.]/
+
+      Dir.foreach(path)
+         .select { |e| e =~ non_dot_char }
+         .map    { |e| File.join(path, e) }
+    end
+
+    def byte_count(path)
+      File.stat(path).size
+    end
 
     def parse_options(argv)
       options = {}
@@ -20,16 +41,9 @@ def parse_options(argv)
         p.on('-a') { options[:include_hidden] = true }
       end
       paths = parser.parse(argv)
+      paths << Dir.pwd if paths.empty?
 
       [options, paths]
     end
-
-    def list_current_directory
-      display.render(Dir.pwd)
-    end
-
-    def list_paths
-      paths.each { |path| display.render(path) }
-    end
   end
 end
diff --git a/samples/part1/lib/rls/display.rb b/samples/part1/lib/rls/display.rb
index de271e5..11150e7 100644
--- a/samples/part1/lib/rls/display.rb
+++ b/samples/part1/lib/rls/display.rb
@@ -1,8 +1,9 @@
 module RLs
   class Display
     def initialize(options)
-      @long_format = options[:long_format]
+      @long_format    = options[:long_format]
       @include_hidden = options[:include_hidden]
+      @max_byte_count = options[:max_byte_count]
     end
 
     def render(path)
@@ -59,7 +60,7 @@ def list(filename)
 
     def formatted(filename)
       if long_format
-        File.open(filename) { |f| RLs::LongFormat.new(f) }
+        File.open(filename) { |f| RLs::LongFormat.new(f, @max_byte_count) }
       else
         filename
       end
diff --git a/samples/part1/lib/rls/long_format.rb b/samples/part1/lib/rls/long_format.rb
index b40fa6c..b279ad2 100644
--- a/samples/part1/lib/rls/long_format.rb
+++ b/samples/part1/lib/rls/long_format.rb
@@ -10,14 +10,15 @@ class LongFormat
       'file'             => '-'
     }
 
-    def initialize(file)
-      @file        = file
-      @stat        = File.stat(@file)
+    def initialize(file, max_byte_count)
+      @file = file
+      @stat = File.stat(@file)
       @permissions = RLs::Permissions.new(@stat)
+      @max_byte_count = max_byte_count
     end
 
     def to_s
-      "#{mode} #{links} #{owner}  #{group} #{bytes} #{last_modified} #{path}"
+      "#{mode} #{links} #{owner}  #{group}#{bytes} #{last_modified} #{path}"
     end
 
     private
@@ -44,7 +45,8 @@ def group
 
     def bytes
       size = stat.size
-      size.to_s.rjust(4)
+      col_width = @max_byte_count.to_s.length + 2
+      size.to_s.rjust(col_width)
     end
 
     def last_modified
diff --git a/samples/part1/ls_tests.rb b/samples/part1/ls_tests.rb
index 4392382..c47cbb6 100644
--- a/samples/part1/ls_tests.rb
+++ b/samples/part1/ls_tests.rb
@@ -17,7 +17,7 @@
 
 check("Hidden files with detailed output", "-a -l")
 
-# check("File glob with detailed output", "-l foo/*.txt")
+check("File glob with detailed output", "-l foo/*.txt")
 
 # check("Invalid directory", "missingdir")
 

From c9374ac5ab0c34bac001e78b0cb6a80f2ff7e042 Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Sun, 8 May 2016 17:58:49 -0400
Subject: [PATCH 07/15] gracefully handle non-existent files/directories

---
 samples/part1/bin/ruby-ls            | 6 +++++-
 samples/part1/lib/rls/application.rb | 2 ++
 samples/part1/ls_tests.rb            | 2 +-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/samples/part1/bin/ruby-ls b/samples/part1/bin/ruby-ls
index b2ea1cf..00e16cf 100755
--- a/samples/part1/bin/ruby-ls
+++ b/samples/part1/bin/ruby-ls
@@ -2,4 +2,8 @@
 
 require_relative '../lib/rls'
 
-RLs::Application.new(ARGV).run
+begin
+  RLs::Application.new(ARGV).run
+rescue Errno::ENOENT => err
+  abort "ls: #{err.message}"
+end
diff --git a/samples/part1/lib/rls/application.rb b/samples/part1/lib/rls/application.rb
index f2e8973..bf15c45 100644
--- a/samples/part1/lib/rls/application.rb
+++ b/samples/part1/lib/rls/application.rb
@@ -32,6 +32,8 @@ def directory_subpaths(path)
 
     def byte_count(path)
       File.stat(path).size
+    rescue Errno::ENOENT => e
+      raise(e, "#{path}: No such file or directory")
     end
 
     def parse_options(argv)
diff --git a/samples/part1/ls_tests.rb b/samples/part1/ls_tests.rb
index c47cbb6..12be17f 100644
--- a/samples/part1/ls_tests.rb
+++ b/samples/part1/ls_tests.rb
@@ -19,7 +19,7 @@
 
 check("File glob with detailed output", "-l foo/*.txt")
 
-# check("Invalid directory", "missingdir")
+check("Invalid directory", "missingdir")
 
 # check("Invalid flag", "-Z")
 

From b3951bdc35991587a52141ab3e8a26a13dffdf47 Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Sun, 8 May 2016 18:14:04 -0400
Subject: [PATCH 08/15] handle invalid option flags

---
 samples/part1/bin/ruby-ls | 4 ++++
 samples/part1/ls_tests.rb | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/samples/part1/bin/ruby-ls b/samples/part1/bin/ruby-ls
index 00e16cf..650ca7e 100755
--- a/samples/part1/bin/ruby-ls
+++ b/samples/part1/bin/ruby-ls
@@ -6,4 +6,8 @@ begin
   RLs::Application.new(ARGV).run
 rescue Errno::ENOENT => err
   abort "ls: #{err.message}"
+rescue OptionParser::InvalidOption => err
+  msg = err.message.sub('invalid', 'illegal').sub(': -', ' -- ')
+  usage = 'usage: ls [-ABCFGHLOPRSTUWabcdefghiklmnopqrstuwx1] [file ...]'
+  abort "ls: #{msg}\n#{usage}"
 end
diff --git a/samples/part1/ls_tests.rb b/samples/part1/ls_tests.rb
index 12be17f..04f0979 100644
--- a/samples/part1/ls_tests.rb
+++ b/samples/part1/ls_tests.rb
@@ -21,7 +21,7 @@
 
 check("Invalid directory", "missingdir")
 
-# check("Invalid flag", "-Z")
+check("Invalid flag", "-Z")
 
 puts "You passed the tests, yay!"
 

From 790fdba103ddb158825e8284a24e815c87ce5d34 Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Tue, 10 May 2016 08:06:07 -0400
Subject: [PATCH 09/15] move option parsing out of application

---
 samples/part1/bin/ruby-ls            | 17 ++++++++++++++---
 samples/part1/lib/rls/application.rb | 24 ++++++++----------------
 2 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/samples/part1/bin/ruby-ls b/samples/part1/bin/ruby-ls
index 650ca7e..6287941 100755
--- a/samples/part1/bin/ruby-ls
+++ b/samples/part1/bin/ruby-ls
@@ -2,12 +2,23 @@
 
 require_relative '../lib/rls'
 
+options = {}
+parser = OptionParser.new do |p|
+  p.on('-l') { options[:long_format]    = true }
+  p.on('-a') { options[:include_hidden] = true }
+end
+
 begin
-  RLs::Application.new(ARGV).run
-rescue Errno::ENOENT => err
-  abort "ls: #{err.message}"
+  paths = parser.parse(ARGV)
 rescue OptionParser::InvalidOption => err
   msg = err.message.sub('invalid', 'illegal').sub(': -', ' -- ')
   usage = 'usage: ls [-ABCFGHLOPRSTUWabcdefghiklmnopqrstuwx1] [file ...]'
   abort "ls: #{msg}\n#{usage}"
 end
+paths << Dir.pwd if paths.empty?
+
+begin
+  RLs::Application.new(options, paths).run
+rescue Errno::ENOENT => err
+  abort "ls: #{err.message}"
+end
diff --git a/samples/part1/lib/rls/application.rb b/samples/part1/lib/rls/application.rb
index bf15c45..860f3e4 100644
--- a/samples/part1/lib/rls/application.rb
+++ b/samples/part1/lib/rls/application.rb
@@ -1,9 +1,9 @@
 module RLs
   class Application
-    def initialize(argv)
-      options, @paths = parse_options(argv)
-      options.merge!(max_byte_count: byte_counts.max)
-      @display = RLs::Display.new(options)
+    def initialize(options, paths)
+      @options = options
+      @paths   = paths
+      @display = RLs::Display.new(display_options)
     end
 
     def run
@@ -12,6 +12,10 @@ def run
 
     private
 
+    def display_options
+      @options.merge(max_byte_count: byte_counts.max)
+    end
+
     def byte_counts
       @paths.flat_map do |p|
         Dir.exist?(p) ? directory_byte_counts(p) : byte_count(p)
@@ -35,17 +39,5 @@ def byte_count(path)
     rescue Errno::ENOENT => e
       raise(e, "#{path}: No such file or directory")
     end
-
-    def parse_options(argv)
-      options = {}
-      parser = OptionParser.new do |p|
-        p.on('-l') { options[:long_format]    = true }
-        p.on('-a') { options[:include_hidden] = true }
-      end
-      paths = parser.parse(argv)
-      paths << Dir.pwd if paths.empty?
-
-      [options, paths]
-    end
   end
 end

From 5face41aaaa2df34f86799c137fdb3ff19a8ab7b Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Tue, 10 May 2016 08:06:36 -0400
Subject: [PATCH 10/15] directly use instance vars internally

Defining private attr_readers does nothing but obscure what's going on. Using instance
variables directly within the class gives a nice visual reminder of where these values
came from.
---
 samples/part1/lib/rls/long_format.rb | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/samples/part1/lib/rls/long_format.rb b/samples/part1/lib/rls/long_format.rb
index b279ad2..f7d300f 100644
--- a/samples/part1/lib/rls/long_format.rb
+++ b/samples/part1/lib/rls/long_format.rb
@@ -18,44 +18,42 @@ def initialize(file, max_byte_count)
     end
 
     def to_s
-      "#{mode} #{links} #{owner}  #{group}#{bytes} #{last_modified} #{path}"
+      "#{mode} #{links} #{owner}  #{group} #{bytes} #{last_modified} #{path}"
     end
 
     private
 
-    attr_reader :file, :stat, :permissions
-
     def mode
-      ftype = FTYPES[stat.ftype]
-      "#{ftype}#{permissions}"
+      ftype = FTYPES[@stat.ftype]
+      "#{ftype}#{@permissions}"
     end
 
     def links
-      nlink = stat.nlink
+      nlink = @stat.nlink
       nlink.to_s.rjust(2)
     end
 
     def owner
-      `id -un #{stat.uid}`.chomp
+      `id -un #{@stat.uid}`.chomp
     end
 
     def group
-      `id -gn #{stat.uid}`.chomp
+      `id -gn #{@stat.uid}`.chomp
     end
 
     def bytes
-      size = stat.size
-      col_width = @max_byte_count.to_s.length + 2
+      size = @stat.size
+      col_width = @max_byte_count.to_s.length + 1
       size.to_s.rjust(col_width)
     end
 
     def last_modified
-      time = stat.mtime
+      time = @stat.mtime
       time.strftime('%b %e %H:%M')
     end
 
     def path
-      file.path
+      @file.path
     end
   end
 end

From eaccc3561fd8387c37971f6ef58eac5ca8b16337 Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Tue, 10 May 2016 08:13:40 -0400
Subject: [PATCH 11/15] rename RLs -> RubyLS

---
 samples/part1/bin/ruby-ls                         | 4 ++--
 samples/part1/lib/rls.rb                          | 6 ------
 samples/part1/lib/ruby_ls.rb                      | 6 ++++++
 samples/part1/lib/{rls => ruby_ls}/application.rb | 4 ++--
 samples/part1/lib/{rls => ruby_ls}/display.rb     | 4 ++--
 samples/part1/lib/{rls => ruby_ls}/long_format.rb | 4 ++--
 samples/part1/lib/{rls => ruby_ls}/permissions.rb | 2 +-
 7 files changed, 15 insertions(+), 15 deletions(-)
 delete mode 100644 samples/part1/lib/rls.rb
 create mode 100644 samples/part1/lib/ruby_ls.rb
 rename samples/part1/lib/{rls => ruby_ls}/application.rb (92%)
 rename samples/part1/lib/{rls => ruby_ls}/display.rb (93%)
 rename samples/part1/lib/{rls => ruby_ls}/long_format.rb (94%)
 rename samples/part1/lib/{rls => ruby_ls}/permissions.rb (97%)

diff --git a/samples/part1/bin/ruby-ls b/samples/part1/bin/ruby-ls
index 6287941..41fea38 100755
--- a/samples/part1/bin/ruby-ls
+++ b/samples/part1/bin/ruby-ls
@@ -1,6 +1,6 @@
 #!/usr/bin/env ruby
 
-require_relative '../lib/rls'
+require_relative '../lib/ruby_ls'
 
 options = {}
 parser = OptionParser.new do |p|
@@ -18,7 +18,7 @@ end
 paths << Dir.pwd if paths.empty?
 
 begin
-  RLs::Application.new(options, paths).run
+  RubyLS::Application.new(options, paths).run
 rescue Errno::ENOENT => err
   abort "ls: #{err.message}"
 end
diff --git a/samples/part1/lib/rls.rb b/samples/part1/lib/rls.rb
deleted file mode 100644
index 11b456c..0000000
--- a/samples/part1/lib/rls.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-require 'optparse'
-
-require_relative 'rls/application'
-require_relative 'rls/display'
-require_relative 'rls/long_format'
-require_relative 'rls/permissions'
diff --git a/samples/part1/lib/ruby_ls.rb b/samples/part1/lib/ruby_ls.rb
new file mode 100644
index 0000000..46ef54d
--- /dev/null
+++ b/samples/part1/lib/ruby_ls.rb
@@ -0,0 +1,6 @@
+require 'optparse'
+
+require_relative 'ruby_ls/application'
+require_relative 'ruby_ls/display'
+require_relative 'ruby_ls/long_format'
+require_relative 'ruby_ls/permissions'
diff --git a/samples/part1/lib/rls/application.rb b/samples/part1/lib/ruby_ls/application.rb
similarity index 92%
rename from samples/part1/lib/rls/application.rb
rename to samples/part1/lib/ruby_ls/application.rb
index 860f3e4..2b6b413 100644
--- a/samples/part1/lib/rls/application.rb
+++ b/samples/part1/lib/ruby_ls/application.rb
@@ -1,9 +1,9 @@
-module RLs
+module RubyLS
   class Application
     def initialize(options, paths)
       @options = options
       @paths   = paths
-      @display = RLs::Display.new(display_options)
+      @display = RubyLS::Display.new(display_options)
     end
 
     def run
diff --git a/samples/part1/lib/rls/display.rb b/samples/part1/lib/ruby_ls/display.rb
similarity index 93%
rename from samples/part1/lib/rls/display.rb
rename to samples/part1/lib/ruby_ls/display.rb
index 11150e7..8da1582 100644
--- a/samples/part1/lib/rls/display.rb
+++ b/samples/part1/lib/ruby_ls/display.rb
@@ -1,4 +1,4 @@
-module RLs
+module RubyLS
   class Display
     def initialize(options)
       @long_format    = options[:long_format]
@@ -60,7 +60,7 @@ def list(filename)
 
     def formatted(filename)
       if long_format
-        File.open(filename) { |f| RLs::LongFormat.new(f, @max_byte_count) }
+        File.open(filename) { |f| RubyLS::LongFormat.new(f, @max_byte_count) }
       else
         filename
       end
diff --git a/samples/part1/lib/rls/long_format.rb b/samples/part1/lib/ruby_ls/long_format.rb
similarity index 94%
rename from samples/part1/lib/rls/long_format.rb
rename to samples/part1/lib/ruby_ls/long_format.rb
index f7d300f..b6cbaad 100644
--- a/samples/part1/lib/rls/long_format.rb
+++ b/samples/part1/lib/ruby_ls/long_format.rb
@@ -1,4 +1,4 @@
-module RLs
+module RubyLS
   class LongFormat
     FTYPES = {
       'blockSpecial'     => 'b',
@@ -13,7 +13,7 @@ class LongFormat
     def initialize(file, max_byte_count)
       @file = file
       @stat = File.stat(@file)
-      @permissions = RLs::Permissions.new(@stat)
+      @permissions = RubyLS::Permissions.new(@stat)
       @max_byte_count = max_byte_count
     end
 
diff --git a/samples/part1/lib/rls/permissions.rb b/samples/part1/lib/ruby_ls/permissions.rb
similarity index 97%
rename from samples/part1/lib/rls/permissions.rb
rename to samples/part1/lib/ruby_ls/permissions.rb
index b58ca86..099dc12 100644
--- a/samples/part1/lib/rls/permissions.rb
+++ b/samples/part1/lib/ruby_ls/permissions.rb
@@ -1,4 +1,4 @@
-module RLs
+module RubyLS
   class Permissions
     ACTORS = [:owner, :group, :other]
     OPERATIONS = [:r, :w, :x]

From 45834c1534da9936efff0b3c4b72fabc50b8c81d Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Tue, 10 May 2016 08:44:33 -0400
Subject: [PATCH 12/15] LongFormat -> FileDetails

Rename and make some small adjustments to accomodate unit testing.
---
 samples/part1/lib/ruby_ls.rb                         |  2 +-
 samples/part1/lib/ruby_ls/display.rb                 | 10 ++++------
 .../lib/ruby_ls/{long_format.rb => file_details.rb}  | 12 +++++++-----
 3 files changed, 12 insertions(+), 12 deletions(-)
 rename samples/part1/lib/ruby_ls/{long_format.rb => file_details.rb} (81%)

diff --git a/samples/part1/lib/ruby_ls.rb b/samples/part1/lib/ruby_ls.rb
index 46ef54d..f70c662 100644
--- a/samples/part1/lib/ruby_ls.rb
+++ b/samples/part1/lib/ruby_ls.rb
@@ -2,5 +2,5 @@
 
 require_relative 'ruby_ls/application'
 require_relative 'ruby_ls/display'
-require_relative 'ruby_ls/long_format'
+require_relative 'ruby_ls/file_details'
 require_relative 'ruby_ls/permissions'
diff --git a/samples/part1/lib/ruby_ls/display.rb b/samples/part1/lib/ruby_ls/display.rb
index 8da1582..ef2b2b1 100644
--- a/samples/part1/lib/ruby_ls/display.rb
+++ b/samples/part1/lib/ruby_ls/display.rb
@@ -16,10 +16,8 @@ def render(path)
 
     private
 
-    attr_reader :long_format, :include_hidden
-
     def render_directory(dirname)
-      list_total_blocks(dirname) if long_format
+      list_total_blocks(dirname) if @long_format
       Dir.foreach(dirname) { |e| list_if_visible(e) }
     end
 
@@ -47,7 +45,7 @@ def list_if_visible(filename)
     end
 
     def show?(filename)
-      include_hidden || !hidden?(filename)
+      @include_hidden || !hidden?(filename)
     end
 
     def hidden?(filename)
@@ -59,8 +57,8 @@ def list(filename)
     end
 
     def formatted(filename)
-      if long_format
-        File.open(filename) { |f| RubyLS::LongFormat.new(f, @max_byte_count) }
+      if @long_format
+        File.open(filename) { |f| RubyLS::FileDetails.new(f, @max_byte_count) }
       else
         filename
       end
diff --git a/samples/part1/lib/ruby_ls/long_format.rb b/samples/part1/lib/ruby_ls/file_details.rb
similarity index 81%
rename from samples/part1/lib/ruby_ls/long_format.rb
rename to samples/part1/lib/ruby_ls/file_details.rb
index b6cbaad..460be86 100644
--- a/samples/part1/lib/ruby_ls/long_format.rb
+++ b/samples/part1/lib/ruby_ls/file_details.rb
@@ -1,5 +1,7 @@
+require 'etc'
+
 module RubyLS
-  class LongFormat
+  class FileDetails
     FTYPES = {
       'blockSpecial'     => 'b',
       'characterSpecial' => 'c',
@@ -10,7 +12,7 @@ class LongFormat
       'file'             => '-'
     }
 
-    def initialize(file, max_byte_count)
+    def initialize(file, max_byte_count = nil)
       @file = file
       @stat = File.stat(@file)
       @permissions = RubyLS::Permissions.new(@stat)
@@ -34,16 +36,16 @@ def links
     end
 
     def owner
-      `id -un #{@stat.uid}`.chomp
+      Etc.getpwuid(@stat.uid).name
     end
 
     def group
-      `id -gn #{@stat.uid}`.chomp
+      Etc.getgrgid(@stat.gid).name
     end
 
     def bytes
       size = @stat.size
-      col_width = @max_byte_count.to_s.length + 1
+      col_width = (@max_byte_count || size).to_s.length + 1
       size.to_s.rjust(col_width)
     end
 

From 33c34047437ae285b5932856fd2ddb832259bec2 Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Tue, 10 May 2016 08:57:45 -0400
Subject: [PATCH 13/15] further accomodate unit tests

---
 samples/part1/lib/ruby_ls/file_details.rb | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/samples/part1/lib/ruby_ls/file_details.rb b/samples/part1/lib/ruby_ls/file_details.rb
index 460be86..7776dc1 100644
--- a/samples/part1/lib/ruby_ls/file_details.rb
+++ b/samples/part1/lib/ruby_ls/file_details.rb
@@ -20,19 +20,24 @@ def initialize(file, max_byte_count = nil)
     end
 
     def to_s
-      "#{mode} #{links} #{owner}  #{group} #{bytes} #{last_modified} #{path}"
+      "#{mode} #{links.to_s.rjust(2)} #{owner}  #{group} #{bytes} #{mtime} #{path}"
+    end
+
+    def [](key)
+      send(key)
     end
 
     private
 
+    attr_reader :permissions
+
     def mode
       ftype = FTYPES[@stat.ftype]
-      "#{ftype}#{@permissions}"
+      "#{ftype}#{permissions}"
     end
 
     def links
-      nlink = @stat.nlink
-      nlink.to_s.rjust(2)
+      @stat.nlink
     end
 
     def owner
@@ -44,12 +49,15 @@ def group
     end
 
     def bytes
-      size = @stat.size
       col_width = (@max_byte_count || size).to_s.length + 1
       size.to_s.rjust(col_width)
     end
 
-    def last_modified
+    def size
+      @stat.size
+    end
+
+    def mtime
       time = @stat.mtime
       time.strftime('%b %e %H:%M')
     end

From 0c88db5891c660fe8c4a013ab209d48cfc028dee Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Tue, 10 May 2016 09:03:01 -0400
Subject: [PATCH 14/15] move require to executable

---
 samples/part1/bin/ruby-ls    | 2 ++
 samples/part1/lib/ruby_ls.rb | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/samples/part1/bin/ruby-ls b/samples/part1/bin/ruby-ls
index 41fea38..c90f1e4 100755
--- a/samples/part1/bin/ruby-ls
+++ b/samples/part1/bin/ruby-ls
@@ -1,5 +1,7 @@
 #!/usr/bin/env ruby
 
+require 'optparse'
+
 require_relative '../lib/ruby_ls'
 
 options = {}
diff --git a/samples/part1/lib/ruby_ls.rb b/samples/part1/lib/ruby_ls.rb
index f70c662..71211d7 100644
--- a/samples/part1/lib/ruby_ls.rb
+++ b/samples/part1/lib/ruby_ls.rb
@@ -1,5 +1,3 @@
-require 'optparse'
-
 require_relative 'ruby_ls/application'
 require_relative 'ruby_ls/display'
 require_relative 'ruby_ls/file_details'

From 726475de03ec807efff71a199d0d2ac36937b49f Mon Sep 17 00:00:00 2001
From: ivanbrennan <ivan.brennan@gmail.com>
Date: Tue, 10 May 2016 09:08:48 -0400
Subject: [PATCH 15/15] clean up a couple methods

---
 samples/part1/lib/ruby_ls/display.rb | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/samples/part1/lib/ruby_ls/display.rb b/samples/part1/lib/ruby_ls/display.rb
index ef2b2b1..1b8d960 100644
--- a/samples/part1/lib/ruby_ls/display.rb
+++ b/samples/part1/lib/ruby_ls/display.rb
@@ -10,7 +10,7 @@ def render(path)
       if Dir.exist?(path)
         render_directory(path)
       else
-        list_if_visible(path)
+        render_file(path)
       end
     end
 
@@ -18,7 +18,7 @@ def render(path)
 
     def render_directory(dirname)
       list_total_blocks(dirname) if @long_format
-      Dir.foreach(dirname) { |e| list_if_visible(e) }
+      Dir.foreach(dirname) { |e| render_file(e) }
     end
 
     def list_total_blocks(dirname)
@@ -40,8 +40,10 @@ def blocks_allocated(path)
       File.stat(path).blocks
     end
 
-    def list_if_visible(filename)
-      list(filename) if show?(filename)
+    def render_file(filename)
+      if show?(filename)
+        puts formatted(filename)
+      end
     end
 
     def show?(filename)
@@ -52,10 +54,6 @@ def hidden?(filename)
       filename[0] == '.'
     end
 
-    def list(filename)
-      puts formatted(filename)
-    end
-
     def formatted(filename)
       if @long_format
         File.open(filename) { |f| RubyLS::FileDetails.new(f, @max_byte_count) }