From 560795b6ee274471bf18e800baba3cbf15956826 Mon Sep 17 00:00:00 2001
From: mayuko hirono <mayuko.hirono@gmail.com>
Date: Sun, 21 Oct 2012 16:27:50 +0900
Subject: [PATCH 1/7] Spec and main class setup.

---
 calendar.rb      |  4 ++++
 calendar_spec.rb | 12 ++++++++++++
 2 files changed, 16 insertions(+)
 create mode 100644 calendar.rb
 create mode 100644 calendar_spec.rb

diff --git a/calendar.rb b/calendar.rb
new file mode 100644
index 0000000..9d5b1b3
--- /dev/null
+++ b/calendar.rb
@@ -0,0 +1,4 @@
+module Calendar
+  def self.convert(date)
+  end
+end
\ No newline at end of file
diff --git a/calendar_spec.rb b/calendar_spec.rb
new file mode 100644
index 0000000..f337a88
--- /dev/null
+++ b/calendar_spec.rb
@@ -0,0 +1,12 @@
+# encoding: utf-8
+
+require 'rubygems'
+require 'rspec'
+require "#{File.dirname(__FILE__)}/calendar"
+
+describe Calendar do
+  it "should return a blank string for nil input" do
+    Calendar.convert(nil).should == nil
+  end
+end
+

From 120efcdbe742c48e812163ba0cf1c04752ca062d Mon Sep 17 00:00:00 2001
From: mayuko hirono <mayuko.hirono@gmail.com>
Date: Sun, 21 Oct 2012 16:39:43 +0900
Subject: [PATCH 2/7] Heisei support

Heisei jump!
---
 calendar.rb      | 5 +++++
 calendar_spec.rb | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/calendar.rb b/calendar.rb
index 9d5b1b3..015603c 100644
--- a/calendar.rb
+++ b/calendar.rb
@@ -1,4 +1,9 @@
+#encoding: utf-8
 module Calendar
   def self.convert(date)
+    return nil unless date
+    year, month, day = date.split('-')
+    japanese_year = year.to_i - 1989 + 1
+    "平成#{japanese_year}年#{month}月#{day}日"
   end
 end
\ No newline at end of file
diff --git a/calendar_spec.rb b/calendar_spec.rb
index f337a88..f0b07c8 100644
--- a/calendar_spec.rb
+++ b/calendar_spec.rb
@@ -8,5 +8,9 @@
   it "should return a blank string for nil input" do
     Calendar.convert(nil).should == nil
   end
+  
+  it "should work for today" do
+    Calendar.convert("2012-10-20").should == "平成24年10月20日"
+  end
 end
 

From 5d433c7397abe2d7905ad168a9d7483a025165cc Mon Sep 17 00:00:00 2001
From: mayuko hirono <mayuko.hirono@gmail.com>
Date: Sun, 21 Oct 2012 16:47:29 +0900
Subject: [PATCH 3/7] Showa date support

Natsukashii na~
---
 calendar.rb      | 8 ++++++--
 calendar_spec.rb | 4 ++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/calendar.rb b/calendar.rb
index 015603c..162457e 100644
--- a/calendar.rb
+++ b/calendar.rb
@@ -3,7 +3,11 @@ module Calendar
   def self.convert(date)
     return nil unless date
     year, month, day = date.split('-')
-    japanese_year = year.to_i - 1989 + 1
-    "平成#{japanese_year}年#{month}月#{day}日"
+    if year.to_i >= 1989
+      japanese_year = "平成#{year.to_i - 1989 + 1}"
+    else
+      japanese_year = "昭和#{year.to_i - 1926 + 1}"
+    end
+    "#{japanese_year}年#{month}月#{day}日"
   end
 end
\ No newline at end of file
diff --git a/calendar_spec.rb b/calendar_spec.rb
index f0b07c8..691cbd5 100644
--- a/calendar_spec.rb
+++ b/calendar_spec.rb
@@ -12,5 +12,9 @@
   it "should work for today" do
     Calendar.convert("2012-10-20").should == "平成24年10月20日"
   end
+
+it "should work for Showa dates (natsukashii)" do
+  Calendar.convert("1979-08-08").should == "昭和54年08月08日"
+end
 end
 

From 8b66432122d2f30c30ec89f135d04e78e8933fca Mon Sep 17 00:00:00 2001
From: mayuko hirono <mayuko.hirono@gmail.com>
Date: Sun, 21 Oct 2012 17:06:49 +0900
Subject: [PATCH 4/7] Support for start of Heisei on 1989-01-08

---
 calendar.rb      | 10 +++++-----
 calendar_spec.rb | 12 +++++++++---
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/calendar.rb b/calendar.rb
index 162457e..5586048 100644
--- a/calendar.rb
+++ b/calendar.rb
@@ -2,12 +2,12 @@
 module Calendar
   def self.convert(date)
     return nil unless date
-    year, month, day = date.split('-')
-    if year.to_i >= 1989
-      japanese_year = "平成#{year.to_i - 1989 + 1}"
+    year, month, day = date.split('-').map(&:to_i)
+    if Date.parse(date) >= Date.parse("1989-01-08")
+      japanese_year = "平成#{(year - 1989 + 1).to_s.rjust(2, '0')}"
     else
-      japanese_year = "昭和#{year.to_i - 1926 + 1}"
+      japanese_year = "昭和#{(year - 1926 + 1).to_s.rjust(2, '0')}"
     end
-    "#{japanese_year}年#{month}月#{day}日"
+    "#{japanese_year}年#{month.to_s.rjust(2, '0')}月#{day.to_s.rjust(2, '0')}日"
   end
 end
\ No newline at end of file
diff --git a/calendar_spec.rb b/calendar_spec.rb
index 691cbd5..3d79e20 100644
--- a/calendar_spec.rb
+++ b/calendar_spec.rb
@@ -13,8 +13,14 @@
     Calendar.convert("2012-10-20").should == "平成24年10月20日"
   end
 
-it "should work for Showa dates (natsukashii)" do
-  Calendar.convert("1979-08-08").should == "昭和54年08月08日"
-end
+  it "should work for border of era" do
+    Calendar.convert("1989-01-07").should == "昭和64年01月07日"
+    Calendar.convert("1989-01-08").should == "平成01年01月08日"
+    Calendar.convert("1989-01-09").should == "平成01年01月09日"
+  end
+
+  it "should work for Showa dates (natsukashii)" do
+    Calendar.convert("1979-08-08").should == "昭和54年08月08日"
+  end
 end
 

From 769d719e44719d195fdf6ed1f780c5f87dbb357d Mon Sep 17 00:00:00 2001
From: mayuko hirono <mayuko.hirono@gmail.com>
Date: Sun, 21 Oct 2012 17:15:17 +0900
Subject: [PATCH 5/7] Taisho support

---
 calendar.rb      | 4 +++-
 calendar_spec.rb | 4 ++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/calendar.rb b/calendar.rb
index 5586048..ef6e7da 100644
--- a/calendar.rb
+++ b/calendar.rb
@@ -5,8 +5,10 @@ def self.convert(date)
     year, month, day = date.split('-').map(&:to_i)
     if Date.parse(date) >= Date.parse("1989-01-08")
       japanese_year = "平成#{(year - 1989 + 1).to_s.rjust(2, '0')}"
-    else
+    elsif Date.parse(date) >= Date.parse("1926-12-25")
       japanese_year = "昭和#{(year - 1926 + 1).to_s.rjust(2, '0')}"
+    else
+      japanese_year = "大正#{(year - 1912 + 1).to_s.rjust(2, '0')}"
     end
     "#{japanese_year}年#{month.to_s.rjust(2, '0')}月#{day.to_s.rjust(2, '0')}日"
   end
diff --git a/calendar_spec.rb b/calendar_spec.rb
index 3d79e20..c25a276 100644
--- a/calendar_spec.rb
+++ b/calendar_spec.rb
@@ -22,5 +22,9 @@
   it "should work for Showa dates (natsukashii)" do
     Calendar.convert("1979-08-08").should == "昭和54年08月08日"
   end
+
+it "should work for Taisho dates (furui)" do
+  Calendar.convert("1912-07-30").should == "大正01年07月30日"
+end
 end
 

From a6929591b2d3557c771b406a6bb1712c08593aad Mon Sep 17 00:00:00 2001
From: mayuko hirono <mayuko.hirono@gmail.com>
Date: Sun, 21 Oct 2012 17:18:59 +0900
Subject: [PATCH 6/7] Meiji date support

---
 calendar.rb      |  4 +++-
 calendar_spec.rb | 10 +++++++---
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/calendar.rb b/calendar.rb
index ef6e7da..2521e4d 100644
--- a/calendar.rb
+++ b/calendar.rb
@@ -7,8 +7,10 @@ def self.convert(date)
       japanese_year = "平成#{(year - 1989 + 1).to_s.rjust(2, '0')}"
     elsif Date.parse(date) >= Date.parse("1926-12-25")
       japanese_year = "昭和#{(year - 1926 + 1).to_s.rjust(2, '0')}"
-    else
+    elsif Date.parse(date) >= Date.parse("1912-07-30")
       japanese_year = "大正#{(year - 1912 + 1).to_s.rjust(2, '0')}"
+    elsif Date.parse(date) >= Date.parse("1868-09-08")
+      japanese_year = "明治#{(year - 1868 + 1).to_s.rjust(2, '0')}"
     end
     "#{japanese_year}年#{month.to_s.rjust(2, '0')}月#{day.to_s.rjust(2, '0')}日"
   end
diff --git a/calendar_spec.rb b/calendar_spec.rb
index c25a276..8c8f97a 100644
--- a/calendar_spec.rb
+++ b/calendar_spec.rb
@@ -23,8 +23,12 @@
     Calendar.convert("1979-08-08").should == "昭和54年08月08日"
   end
 
-it "should work for Taisho dates (furui)" do
-  Calendar.convert("1912-07-30").should == "大正01年07月30日"
-end
+  it "should work for Taisho dates (furui)" do
+    Calendar.convert("1912-07-30").should == "大正01年07月30日"
+  end
+
+  it "should work for Meiji dates (motto furui)" do
+    Calendar.convert("1868-09-08").should == "明治01年09月08日"
+  end
 end
 

From a3452eb25d189d265a476cac335c5eca71d40918 Mon Sep 17 00:00:00 2001
From: mayuko hirono <mayuko.hirono@gmail.com>
Date: Sun, 21 Oct 2012 17:22:18 +0900
Subject: [PATCH 7/7] Throws error for dates pre Meiji era

Calculating dates reliably before this is hard :(
---
 calendar.rb      | 2 ++
 calendar_spec.rb | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/calendar.rb b/calendar.rb
index 2521e4d..3f4cf37 100644
--- a/calendar.rb
+++ b/calendar.rb
@@ -11,6 +11,8 @@ def self.convert(date)
       japanese_year = "大正#{(year - 1912 + 1).to_s.rjust(2, '0')}"
     elsif Date.parse(date) >= Date.parse("1868-09-08")
       japanese_year = "明治#{(year - 1868 + 1).to_s.rjust(2, '0')}"
+    else
+      raise ArgumentError, "Dates earlier than the Meiji era are unsupported"
     end
     "#{japanese_year}年#{month.to_s.rjust(2, '0')}月#{day.to_s.rjust(2, '0')}日"
   end
diff --git a/calendar_spec.rb b/calendar_spec.rb
index 8c8f97a..ec493b7 100644
--- a/calendar_spec.rb
+++ b/calendar_spec.rb
@@ -30,5 +30,9 @@
   it "should work for Meiji dates (motto furui)" do
     Calendar.convert("1868-09-08").should == "明治01年09月08日"
   end
+
+  it "should throw error for pre-Meiji dates" do
+    expect{Calendar.convert("1868-09-01")}.to raise_error(ArgumentError)
+  end
 end