class Gem::Platform

def self.installable?(spec)
  if spec.respond_to? :installable_platform?
    spec.installable_platform?
  else
    match_spec? spec
  end
end

def self.local(refresh: false)
  return @local if @local && !refresh
  @local = begin
    arch = Gem.target_rbconfig["arch"]
    arch = "#{arch}_60" if /mswin(?:32|64)$/.match?(arch)
    new(arch)
  end
end

def self.match_gem?(platform, gem_name)
  raise "Not a string: #{gem_name.inspect}" unless String === gem_name
  if REUSE_AS_BINARY_ON_TRUFFLERUBY.include?(gem_name)
    match_platforms?(platform, [Gem::Platform::RUBY, Gem::Platform.local])
  else
    match_platforms?(platform, Gem.platforms)
  end
end

def self.match_gem?(platform, gem_name)
  match_platforms?(platform, Gem.platforms)
end

def self.match_platforms?(platform, platforms)
  platform = Gem::Platform.new(platform) unless platform.is_a?(Gem::Platform)
  platforms.any? do |local_platform|
    platform.nil? ||
      local_platform == platform ||
      (local_platform != Gem::Platform::RUBY && platform =~ local_platform)
  end
end

def self.match_spec?(spec)
  match_gem?(spec.platform, spec.name)
end

def self.new(arch) # :nodoc:
  case arch
  when Gem::Platform::CURRENT then
    Gem::Platform.local
  when Gem::Platform::RUBY, nil, "" then
    Gem::Platform::RUBY
  else
    super
  end
end

def self.sort_priority(platform)
  platform == Gem::Platform::RUBY ? -1 : 1
end

def ==(other)
  self.class === other && to_a == other.to_a
end

def ===(other)
  return nil unless Gem::Platform === other
  # universal-mingw32 matches x64-mingw-ucrt
  return true if (@cpu == "universal" || other.cpu == "universal") &&
                 @os.start_with?("mingw") && other.os.start_with?("mingw")
  # cpu
  ([nil,"universal"].include?(@cpu) || [nil, "universal"].include?(other.cpu) || @cpu == other.cpu ||
  (@cpu == "arm" && other.cpu.start_with?("armv"))) &&
    # os
    @os == other.os &&
    # version
    (
      (@os != "linux" && (@version.nil? || other.version.nil?)) ||
      (@os == "linux" && (normalized_linux_version == other.normalized_linux_version || ["musl#{@version}", "musleabi#{@version}", "musleabihf#{@version}"].include?(other.version))) ||
      @version == other.version
    )
end

def =~(other)
  case other
  when Gem::Platform then # nop
  when String then
    # This data is from http://gems.rubyforge.org/gems/yaml on 19 Aug 2007
    other = case other
            when /^i686-darwin(\d)/     then ["x86",       "darwin",  $1]
            when /^i\d86-linux/         then ["x86",       "linux",   nil]
            when "java", "jruby"        then [nil,         "java",    nil]
            when /^dalvik(\d+)?$/       then [nil,         "dalvik",  $1]
            when /dotnet(\-(\d+\.\d+))?/ then ["universal","dotnet",  $2]
            when /mswin32(\_(\d+))?/    then ["x86",       "mswin32", $2]
            when /mswin64(\_(\d+))?/    then ["x64",       "mswin64", $2]
            when "powerpc-darwin"       then ["powerpc",   "darwin",  nil]
            when /powerpc-darwin(\d)/   then ["powerpc",   "darwin",  $1]
            when /sparc-solaris2.8/     then ["sparc",     "solaris", "2.8"]
            when /universal-darwin(\d)/ then ["universal", "darwin",  $1]
            else other
    end
    other = Gem::Platform.new other
  else
    return nil
  end
  self === other
end

def cpu_match(spec_platform, user_platform)
  if spec_platform.cpu == user_platform.cpu
    0
  elsif spec_platform.cpu == "arm" && user_platform.cpu.to_s.start_with?("arm")
    0
  elsif spec_platform.cpu.nil? || spec_platform.cpu == "universal"
    1
  else
    2
  end
end

def deconstruct_keys(keys)
  { cpu: @cpu, os: @os, version: @version }
end

def generic(platform)
  return Gem::Platform::RUBY if platform.nil? || platform == Gem::Platform::RUBY
  GENERIC_CACHE[platform] ||= begin
    found = GENERICS.find do |match|
      platform === match
    end
    found || Gem::Platform::RUBY
  end
end

def hash # :nodoc:
  to_a.hash
end

def initialize(arch)
  case arch
  when Array then
    @cpu, @os, @version = arch
  when String then
    cpu, os = arch.sub(/-+$/, "").split("-", 2)
    @cpu = if cpu&.match?(/i\d86/)
      "x86"
    else
      cpu
    end
    if os.nil?
      @cpu = nil
      os = cpu
    end # legacy jruby
    @os, @version = case os
                    when /aix-?(\d+)?/ then                ["aix",     $1]
                    when /cygwin/ then                     ["cygwin",  nil]
                    when /darwin-?(\d+)?/ then             ["darwin",  $1]
                    when "macruby" then                    ["macruby", nil]
                    when /^macruby-?(\d+(?:\.\d+)*)?/ then ["macruby", $1]
                    when /freebsd-?(\d+)?/ then            ["freebsd", $1]
                    when "java", "jruby" then              ["java",    nil]
                    when /^java-?(\d+(?:\.\d+)*)?/ then    ["java",    $1]
                    when /^dalvik-?(\d+)?$/ then           ["dalvik",  $1]
                    when /^dotnet$/ then                   ["dotnet",  nil]
                    when /^dotnet-?(\d+(?:\.\d+)*)?/ then  ["dotnet",  $1]
                    when /linux-?(\w+)?/ then              ["linux",   $1]
                    when /mingw32/ then                    ["mingw32", nil]
                    when /mingw-?(\w+)?/ then              ["mingw",   $1]
                    when /(mswin\d+)(?:[_-](\d+))?/ then
                      os = $1
                      version = $2
                      @cpu = "x86" if @cpu.nil? && os.end_with?("32")
                      [os, version]
                    when /netbsdelf/ then                  ["netbsdelf", nil]
                    when /openbsd-?(\d+\.\d+)?/ then       ["openbsd",   $1]
                    when /solaris-?(\d+\.\d+)?/ then       ["solaris",   $1]
                    when /wasi/ then                       ["wasi",      nil]
                    # test
                    when /^(\w+_platform)-?(\d+)?/ then    [$1,          $2]
                    else ["unknown", nil]
    end
  when Gem::Platform then
    @cpu = arch.cpu
    @os = arch.os
    @version = arch.version
  else
    raise ArgumentError, "invalid argument #{arch.inspect}"
  end
end

def normalized_linux_version
  return nil unless @version
  without_gnu_nor_abi_modifiers = @version.sub(/\Agnu/, "").sub(/eabi(hf)?\Z/, "")
  return nil if without_gnu_nor_abi_modifiers.empty?
  without_gnu_nor_abi_modifiers
end

def os_match(spec_platform, user_platform)
  if spec_platform.os == user_platform.os
    0
  else
    1
  end
end

def platform_specificity_match(spec_platform, user_platform)
  return -1 if spec_platform == user_platform
  return 1_000_000 if spec_platform.nil? || spec_platform == Gem::Platform::RUBY || user_platform == Gem::Platform::RUBY
  os_match(spec_platform, user_platform) +
    cpu_match(spec_platform, user_platform) * 10 +
    version_match(spec_platform, user_platform) * 100
end

def same_deps?(spec, exemplary_spec)
  spec.required_ruby_version == exemplary_spec.required_ruby_version &&
    spec.required_rubygems_version == exemplary_spec.required_rubygems_version &&
    spec.dependencies.sort == exemplary_spec.dependencies.sort
end

def same_specificity?(platform, spec, exemplary_spec)
  platform_specificity_match(spec.platform, platform) == platform_specificity_match(exemplary_spec.platform, platform)
end

def sort_and_filter_best_platform_match(matching, platform)
  return matching if matching.one?
  exact = matching.select {|spec| spec.platform == platform }
  return exact if exact.any?
  sorted_matching = sort_best_platform_match(matching, platform)
  exemplary_spec = sorted_matching.first
  sorted_matching.take_while {|spec| same_specificity?(platform, spec, exemplary_spec) && same_deps?(spec, exemplary_spec) }
end

def sort_best_platform_match(matching, platform)
  matching.sort_by.with_index do |spec, i|
    [
      platform_specificity_match(spec.platform, platform),
      i, # for stable sort
    ]
  end
end

def to_a
  [@cpu, @os, @version]
end

def to_s
  to_a.compact.join(@cpu.nil? ? "" : "-")
end

def version_match(spec_platform, user_platform)
  if spec_platform.version == user_platform.version
    0
  elsif spec_platform.version.nil?
    1
  else
    2
  end
end