Initial commit of build script.

At this stage it works for me, but the code is a mess, options are not clearly defined. Will refactor later.

.gitignore

@@ -0,0 +1,4 @@
+.DS_Store
+builds
+sources
+tarballs

build.rb

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+#!/usr/bin/env ruby
+
+require 'json'
+require 'date'
+
+
+#
+# Config
+#
+
+DOWNLOAD_URL = "https://github.com/emacsmirror/emacs/tarball/%s"
+LATEST_URL   = "https://api.github.com/repos/emacsmirror/emacs/commits?sha=%s"
+
+ROOT_DIR    = File.expand_path('..', __FILE__)
+TARBALL_DIR = "#{ROOT_DIR}/tarballs"
+SOURCES_DIR  = "#{ROOT_DIR}/sources"
+BUILDS_DIR  = "#{ROOT_DIR}/builds"
+
+
+#
+# Patches
+#
+
+def patches
+  p = []
+
+  if !ARGV.include?('--no-fullscreen')
+    p << 'https://raw.github.com/gist/1012927'
+  end
+
+  if ARGV.include?('--srgb')
+    p << 'https://raw.github.com/gist/1361934'
+  end
+
+  p
+end
+
+
+#
+# Main
+#
+
+def main
+  ref = ARGV.shift
+
+  meta    = get_ref_info(ref)
+
+  if meta['sha'] && meta['date']
+    tarball = download_tarball(meta['sha'])
+    source  = extract_tarball(tarball, patches)
+    app     = compile_source(source)
+
+    archive_app(app, meta['sha'], meta['date'])
+  else
+    raise "\nERROR: Failed to get commit info from GitHub API."
+  end
+end
+
+
+#
+# Core Methods
+#
+
+def download_tarball(sha)
+  mkdir TARBALL_DIR
+
+  url = (DOWNLOAD_URL % sha)
+
+  filename = "emacsmirror-emacs-#{sha[0..6]}.tgz"
+  target   = File.join(TARBALL_DIR, filename)
+
+  if !File.exist?(target)
+    puts "\nDownloading tarball from GitHub. This could take a while, " +
+         "please be patient."
+    system "curl -L \"#{url}\" -o \"#{target}\""
+    raise "\nERROR: Download failed." unless File.exist?(target)
+  else
+    puts "\nINFO: #{filename} already exists locally, attempting to use."
+  end
+  target
+end
+
+def extract_tarball(filename, patches = [])
+  mkdir SOURCES_DIR
+
+  dirname = File.basename(filename).gsub(/\.\w+$/, '')
+  target = "#{SOURCES_DIR}/#{dirname}"
+
+  if !File.exist?(target)
+    puts "\nExtracting tarball..."
+    system "tar -xzf \"#{filename}\" -C \"#{SOURCES_DIR}\""
+    raise "\nERROR: Tarball extraction failed." unless File.exist?(target)
+    patches.each do |url|
+      apply_patch(url, target)
+    end
+  else
+    puts "\nINFO: #{dirname} source tree exists, attempting to use."
+  end
+  target
+end
+
+def compile_source(source)
+  target = "#{source}/nextstep"
+
+  if !File.exist?("#{target}/Emacs.app")
+    puts "\nCompiling from source. This will take a while..."
+
+    if File.exist? "#{source}/autogen/copy_autogen"
+      system "cd \"#{source}\" && autogen/copy_autogen"
+    end
+
+    system "cd \"#{source}\" && ./configure --with-ns"
+    system "cd \"#{source}\" && make install"
+
+    raise "\nERROR: Build failed." unless File.exist?("#{target}/Emacs.app")
+  else
+    puts "\nINFO: Emacs.app already exists in " +
+         "\"#{target.gsub(ROOT_DIR + '/', '')}\", attempting to use."
+  end
+  "#{target}/Emacs.app"
+end
+
+def archive_app(app, sha, date)
+  mkdir BUILDS_DIR
+
+  filename = "Emacs.app-#{date}-(#{sha[0..6]}).tbz"
+  target   = "#{BUILDS_DIR}/#{filename}"
+
+  app_base = File.basename(app)
+  app_dir  = File.dirname(app)
+
+  if !File.exist?(target)
+    puts "\nCreating #{filename} archive in \"#{BUILDS_DIR}\"..."
+    system "cd \"#{app_dir}\" && tar -cjf \"#{target}\" \"#{app_base}\""
+  else
+    puts "\nINFO: #{filename} archive exists in " +
+         "#{BUILDS_DIR.gsub(ROOT_DIR + '/', '')}, skipping archving."
+  end
+end
+
+
+#
+# Helper Methods
+#
+
+def mkdir(dir)
+  system "mkdir -p \"#{dir}\""
+end
+
+def get_ref_info(ref = 'master')
+  response = `curl "#{LATEST_URL % ref}" 2>/dev/null`
+  meta = JSON.parse(response).first
+  return {
+    'sha' => meta['sha'],
+    'date' => Date.parse(meta['commit']['committer']['date'])
+  }
+end
+
+def apply_patch(url, target)
+  raise "ERROR: \"#{target}\" does not exist." unless File.exist?(target)
+  system "mkdir -p \"#{target}/patches\""
+
+  patch_file = "#{target}/patches/patch-{num}.diff"
+  num = 1
+  while File.exist? patch_file.gsub('{num}', num.to_s.rjust(3, '0'))
+    num += 1
+  end
+  patch_file.gsub!('{num}', num.to_s.rjust(3, '0'))
+
+  puts "Downloading patch: #{url}"
+  system "curl -L# \"#{url}\" -o \"#{patch_file}\""
+
+  puts "Applying patch..."
+  system "cd \"#{target}\" && patch -f -p1 -i \"#{patch_file}\""
+end
+
+
+#
+# Run it!
+#
+
+main