require "cmd/tap"
require "formula_versions"
require "migrator"
require "formulary"
require "descriptions"

module Homebrew
  def update_report
    # migrate to new directories based tap structure
    migrate_taps

    report = Report.new
    master_updater = Reporter.new(HOMEBREW_REPOSITORY)
    master_updated = master_updater.updated?
    if master_updated
      initial_short = shorten_revision(master_updater.initial_revision)
      current_short = shorten_revision(master_updater.current_revision)
      puts "Updated Homebrew from #{initial_short} to #{current_short}."
    end
    report.update(master_updater.report)

    updated_taps = []
    Tap.each do |tap|
      next unless tap.git?
      tap.path.cd do
        updater = Reporter.new(tap.path)
        updated_taps << tap.name if updater.updated?
        report.update(updater.report) do |_key, oldval, newval|
          oldval.concat(newval)
        end
      end
    end
    unless updated_taps.empty?
      puts "Updated #{updated_taps.size} tap#{plural(updated_taps.size)} " \
           "(#{updated_taps.join(", ")})."
    end

    if !master_updated && updated_taps.empty? && !ARGV.verbose?
      puts "Already up-to-date."
    end

    Tap.clear_cache
    Tap.each(&:link_manpages)

    # automatically tap any migrated formulae's new tap
    report.select_formula(:D).each do |f|
      next unless (dir = HOMEBREW_CELLAR/f).exist?
      migration = TAP_MIGRATIONS[f]
      next unless migration
      tap = Tap.fetch(*migration.split("/"))
      tap.install unless tap.installed?

      # update tap for each Tab
      tabs = dir.subdirs.map { |d| Tab.for_keg(Keg.new(d)) }
      next if tabs.first.source["tap"] != "Homebrew/homebrew"
      tabs.each { |tab| tab.source["tap"] = "#{tap.user}/homebrew-#{tap.repo}" }
      tabs.each(&:write)
    end if load_tap_migrations

    load_formula_renames
    report.update_renamed

    # Migrate installed renamed formulae from core and taps.
    report.select_formula(:R).each do |oldname, newname|
      if oldname.include?("/")
        user, repo, oldname = oldname.split("/", 3)
        newname = newname.split("/", 3).last
      else
        user = "homebrew"
        repo = "homebrew"
      end

      next unless (dir = HOMEBREW_CELLAR/oldname).directory? && !dir.subdirs.empty?

      begin
        f = Formulary.factory("#{user}/#{repo}/#{newname}")
      # short term fix to prevent situation like https://github.com/Homebrew/homebrew/issues/45616
      rescue Exception
      end

      next unless f

      begin
        migrator = Migrator.new(f)
        migrator.migrate
      rescue Migrator::MigratorDifferentTapsError
      end
    end

    if report.empty?
      puts "No changes to formulae." if master_updated || !updated_taps.empty?
    else
      report.dump
    end
    Descriptions.update_cache(report)
  end

  private

  def shorten_revision(revision)
    `git rev-parse --short #{revision}`.chomp
  end

  def load_tap_migrations
    load "tap_migrations.rb"
  rescue LoadError
    false
  end

  def load_formula_renames
    load "formula_renames.rb"
  rescue LoadError
    false
  end
end

class Reporter
  class ReporterRevisionUnsetError < RuntimeError
    def initialize(var_name)
      super "#{var_name} is unset!"
    end
  end

  attr_reader :tap, :initial_revision, :current_revision

  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
      tap.path.to_s.
        strip_prefix(Tap::TAP_DIRECTORY.to_s).
        tr("^A-Za-z0-9", "_").
        upcase
    end
  end

  def diff
    Utils.popen_read(
      "git", "-C", tap.path, "diff-tree", "-r", "--name-status", "--diff-filter=AMDR",
      "-M85%", initial_revision, current_revision
    )
  end
end

class Report
  def initialize
    @hash = {}
  end

  def fetch(*args, &block)
    @hash.fetch(*args, &block)
  end

  def update(*args, &block)
    @hash.update(*args, &block)
  end

  def empty?
    @hash.empty?
  end

  def dump
    # Key Legend: Added (A), Copied (C), Deleted (D), Modified (M), Renamed (R)

    dump_formula_report :A, "New Formulae"
    dump_formula_report :M, "Updated Formulae"
    dump_formula_report :R, "Renamed Formulae"
    dump_formula_report :D, "Deleted Formulae"
  end

  def update_renamed
    renamed_formulae = []

    fetch(:D, []).each do |path|
      case path.to_s
      when HOMEBREW_TAP_PATH_REGEX
        oldname = path.basename(".rb").to_s
        next unless newname = Tap.fetch($1, $2).formula_renames[oldname]
      else
        oldname = path.basename(".rb").to_s
        next unless newname = CoreFormulaRepository.instance.formula_renames[oldname]
      end

      if fetch(:A, []).include?(newpath = path.dirname.join("#{newname}.rb"))
        renamed_formulae << [path, newpath]
      end
    end

    unless renamed_formulae.empty?
      @hash[:A] -= renamed_formulae.map(&:last) if @hash[:A]
      @hash[:D] -= renamed_formulae.map(&:first) if @hash[:D]
      @hash[:R] = renamed_formulae
    end
  end

  def select_formula(key)
    fetch(key, []).map do |path, newpath|
      if path.to_s =~ HOMEBREW_TAP_PATH_REGEX
        tap = Tap.fetch($1, $2)
        if newpath
          ["#{tap}/#{path.basename(".rb")}", "#{tap}/#{newpath.basename(".rb")}"]
        else
          "#{tap}/#{path.basename(".rb")}"
        end
      elsif newpath
        ["#{path.basename(".rb")}", "#{newpath.basename(".rb")}"]
      else
        path.basename(".rb").to_s
      end
    end.sort
  end

  def dump_formula_report(key, title)
    formula = select_formula(key).map do |name, new_name|
      # Format list items of renamed formulae
      if key == :R
        new_name = pretty_installed(new_name) if installed?(name)
        "#{name} -> #{new_name}"
      else
        installed?(name) ? pretty_installed(name) : name
      end
    end

    unless formula.empty?
      # Dump formula list.
      ohai title
      puts_columns(formula)
    end
  end

  def installed?(formula)
    (HOMEBREW_CELLAR/formula.split("/").last).directory?
  end
end