From 96977c8384292eabaee4c8089fe76eaf94d783cc Mon Sep 17 00:00:00 2001
From: sue445 <sue445@sue445.net>
Date: Sat, 24 Jan 2015 21:42:11 +0900
Subject: [PATCH] Add compare link between older version and newer version

---
 lib/github_changelog_generator.rb | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/lib/github_changelog_generator.rb b/lib/github_changelog_generator.rb
index dcf2e16..33d3fdf 100755
--- a/lib/github_changelog_generator.rb
+++ b/lib/github_changelog_generator.rb
@@ -240,10 +240,12 @@ module GitHubChangelogGenerator
       newer_tag_name = newer_tag['name']
 
       if older_tag.nil?
+        older_tag_name = nil
         filtered_pull_requests = delete_by_time(@pull_requests, :merged_at, newer_tag_time)
         filtered_issues = delete_by_time(@issues, :closed_at, newer_tag_time)
       else
         older_tag_time = self.get_time_of_tag(older_tag)
+        older_tag_name = older_tag['name']
         filtered_pull_requests = delete_by_time(@pull_requests, :merged_at, newer_tag_time, older_tag_time)
         filtered_issues = delete_by_time(@issues, :closed_at, newer_tag_time, older_tag_time)
       end
@@ -285,7 +287,7 @@ module GitHubChangelogGenerator
         filtered_issues |= issues_to_add
       end
 
-      self.create_log(filtered_pull_requests, filtered_issues, newer_tag_name, newer_tag_time)
+      self.create_log(filtered_pull_requests, filtered_issues, newer_tag_name, newer_tag_time, older_tag_name)
 
     end
 
@@ -315,13 +317,19 @@ module GitHubChangelogGenerator
 # @param [Array] issues
 # @param [String] tag_name
 # @param [String] tag_time
+# @param [String] older_tag_name
 # @return [String]
-    def create_log(pull_requests, issues, tag_name, tag_time)
+    def create_log(pull_requests, issues, tag_name, tag_time, older_tag_name = nil)
 
       github_site = options[:github_site] || 'https://github.com'
 
+      project_url = "#{github_site}/#{@options[:user]}/#{@options[:project]}"
+
       # Generate tag name and link
-      log = "## [#{tag_name}](#{github_site}/#{@options[:user]}/#{@options[:project]}/tree/#{tag_name})\n"
+      log = "## [#{tag_name}](#{project_url}/tree/#{tag_name})\n"
+
+      # Generate compare link
+      log += "[Full Changelog](#{project_url}/compare/#{older_tag_name}...#{tag_name})\n" if older_tag_name
 
       #Generate date string:
       time_string = tag_time.strftime @options[:format]
@@ -456,4 +464,4 @@ module GitHubChangelogGenerator
     GitHubChangelogGenerator::ChangelogGenerator.new.compund_changelog
   end
 
-end
\ No newline at end of file
+end