update-report: use tap inside Reporter

* Avoid tons of unnecessary file path manipulation. Use abstraction
offered by Tap class if possible.
* Handle formula rename/tap migration inside reporter in per tap basis.
* Avoid duplicated computation.
* Remove redundant/dead code.

Library/Homebrew/cmd/update-report.rb

@@ -115,119 +115,143 @@ module Homebrew
 end
 
 class Reporter
-  attr_reader :initial_revision, :current_revision, :repository
+  class ReporterRevisionUnsetError < RuntimeError
+    def initialize(var_name)
+      super "#{var_name} is unset!"
+    end
+  end
 
-  def self.repository_variable(repository)
+  attr_reader :tap, :initial_revision, :current_revision
-    if repository == HOMEBREW_REPOSITORY
+
+  def initialize(tap)
+    @tap = tap
+
+    initial_revision_var = "HOMEBREW_UPDATE_BEFORE#{repo_var}"
+    @initial_revision = ENV[initial_revision_var].to_s
+    raise ReporterRevisionUnsetError, initial_revision_var if @initial_revision.empty?
+
+    current_revision_var = "HOMEBREW_UPDATE_AFTER#{repo_var}"
+    @current_revision = ENV[current_revision_var].to_s
+    raise ReporterRevisionUnsetError, current_revision_var if @current_revision.empty?
+  end
+
+  def report
+    return @report if @report
+
+    @report = Hash.new { |h, k| h[k] = [] }
+    return @report unless updated?
+
+    diff.each_line do |line|
+      status, *paths = line.split
+      src = Pathname.new paths.first
+      dst = Pathname.new paths.last
+
+      next unless dst.extname == ".rb"
+      next unless paths.any? { |p| tap.formula_file?(p) }
+
+      case status
+      when "A", "D"
+        @report[status.to_sym] << tap.formula_file_to_name(src)
+      when "M"
+        begin
+          formula = Formulary.factory(tap.path/src)
+          new_version = formula.pkg_version
+          old_version = FormulaVersions.new(formula).formula_at_revision(@initial_revision, &:pkg_version)
+          next if new_version == old_version
+        rescue Exception => e
+          onoe e if ARGV.homebrew_developer?
+        end
+        @report[:M] << tap.formula_file_to_name(src)
+      when /^R\d{0,3}/
+        @report[:D] << tap.formula_file_to_name(src) if tap.formula_file?(src)
+        @report[:A] << tap.formula_file_to_name(dst) if tap.formula_file?(dst)
+      end
+    end
+
+    renamed_formulae = []
+    @report[:D].each do |old_full_name|
+      old_name = old_full_name.split("/").last
+      new_name = tap.formula_renames[old_name]
+      next unless new_name
+
+      if tap.core_formula_repository?
+        new_full_name = new_name
+      else
+        new_full_name = "#{tap}/#{new_full_name}"
+      end
+
+      renamed_formulae << [old_full_name, new_full_name] if @report[:A].include? new_full_name
+    end
+
+    unless renamed_formulae.empty?
+      @report[:A] -= renamed_formulae.map(&:last)
+      @report[:D] -= renamed_formulae.map(&:first)
+      @report[:R] = renamed_formulae
+    end
+
+    @report
+  end
+
+  def updated?
+    initial_revision != current_revision
+  end
+
+  def migrate_tap_migration
+    report[:D].each do |full_name|
+      name = full_name.split("/").last
+      next unless (dir = HOMEBREW_CELLAR/name).exist? # skip if formula is not installed.
+      next unless new_tap_name = tap.tap_migrations[name] # skip if formula is not in tap_migrations list.
+      tabs = dir.subdirs.map { |d| Tab.for_keg(Keg.new(d)) }
+      next unless tabs.first.tap == tap # skip if installed formula is not from this tap.
+      new_tap = Tap.fetch(new_tap_name)
+      new_tap.install unless new_tap.installed?
+      # update tap for each Tab
+      tabs.each { |tab| tab.tap = new_tap }
+      tabs.each(&:write)
+    end
+  end
+
+  def migrate_formula_rename
+    report[:R].each do |old_full_name, new_full_name|
+      old_name = old_full_name.split("/").last
+      next unless (dir = HOMEBREW_CELLAR/old_name).directory? && !dir.subdirs.empty?
+
+      begin
+        f = Formulary.factory(new_full_name)
+      rescue Exception => e
+        onoe e if ARGV.homebrew_developer?
+        next
+      end
+
+      begin
+        migrator = Migrator.new(f)
+        migrator.migrate
+      rescue Migrator::MigratorDifferentTapsError
+      rescue Exception => e
+        onoe e
+      end
+    end
+  end
+
+  private
+
+  def repo_var
+    @repo_var ||= if tap.path == HOMEBREW_REPOSITORY
       ""
     else
-      repository.to_s.
+      tap.path.to_s.
         strip_prefix(Tap::TAP_DIRECTORY.to_s).
         tr("^A-Za-z0-9", "_").
         upcase
     end
   end
 
-  def initialize(repository)
-    @repository = repository
-
-    repo_var = Reporter.repository_variable(@repository)
-    initial_revision_var = "HOMEBREW_UPDATE_BEFORE#{repo_var}"
-    @initial_revision = ENV[initial_revision_var].to_s
-    if @initial_revision.empty?
-      raise "#{initial_revision_var} is unset!" if ARGV.homebrew_developer?
-      raise "update-report should not be called directly!"
-    end
-
-    current_revision_var = "HOMEBREW_UPDATE_AFTER#{repo_var}"
-    @current_revision = ENV[current_revision_var].to_s
-    if @current_revision.empty?
-      raise "#{current_revision_var} is unset!" if ARGV.homebrew_developer?
-      raise "update-report should not be called directly!"
-    end
-  end
-
-  def report
-    map = Hash.new { |h, k| h[k] = [] }
-
-    if initial_revision && initial_revision != current_revision
-      wc_revision = read_current_revision
-
-      diff.each_line do |line|
-        status, *paths = line.split
-        src = paths.first
-        dst = paths.last
-
-        next unless File.extname(dst) == ".rb"
-        next unless paths.any? { |p| File.dirname(p) == formula_directory }
-
-        case status
-        when "A", "D"
-          map[status.to_sym] << repository.join(src)
-        when "M"
-          file = repository.join(src)
-          begin
-            formula = Formulary.factory(file)
-            new_version = if wc_revision == current_revision
-              formula.pkg_version
-            else
-              FormulaVersions.new(formula).formula_at_revision(@current_revision, &:pkg_version)
-            end
-            old_version = FormulaVersions.new(formula).formula_at_revision(@initial_revision, &:pkg_version)
-            next if new_version == old_version
-          # short term fix to prevent situation like https://github.com/Homebrew/homebrew/issues/45616
-          rescue Exception => e
-            onoe e if ARGV.homebrew_developer?
-          end
-          map[:M] << file
-        when /^R\d{0,3}/
-          map[:D] << repository.join(src) if File.dirname(src) == formula_directory
-          map[:A] << repository.join(dst) if File.dirname(dst) == formula_directory
-        end
-      end
-    end
-
-    map
-  end
-
-  def updated?
-    initial_revision && initial_revision != current_revision
-  end
-
-  private
-
-  def formula_directory
-    if repository == HOMEBREW_REPOSITORY
-      "Library/Formula"
-    elsif repository.join("Formula").directory?
-      "Formula"
-    elsif repository.join("HomebrewFormula").directory?
-      "HomebrewFormula"
-    else
-      "."
-    end
-  end
-
-  def read_current_revision
-    `git rev-parse -q --verify HEAD`.chomp
-  end
-
   def diff
     Utils.popen_read(
-      "git", "diff-tree", "-r", "--name-status", "--diff-filter=AMDR",
+      "git", "-C", tap.path, "diff-tree", "-r", "--name-status", "--diff-filter=AMDR",
       "-M85%", initial_revision, current_revision
     )
   end
-
-  def `(cmd)
-    out = super
-    unless $?.success?
-      $stderr.puts(out) unless out.empty?
-      raise ErrorDuringExecution.new(cmd)
-    end
-    ohai(cmd, out) if ARGV.verbose?
-    out
-  end
 end
 
 class Report