class Bundler::Resolver

def self.resolve(requirements, index, source_requirements = {}, base = [], ruby_version = nil)
  base = SpecSet.new(base) unless base.is_a?(SpecSet)
  resolver = new(index, source_requirements, base, ruby_version)
  result = resolver.start(requirements)
  SpecSet.new(result)
end

def after_resolution
  Bundler.ui.info ""
end

def amount_constrained(dependency)
  @amount_constrained ||= {}
  @amount_constrained[dependency.name] ||= begin
    if (base = @base[dependency.name]) && !base.empty?
      dependency.requirement.satisfied_by?(base.first.version) ? 0 : 1
    else
      base_dep = Dependency.new dependency.name, ">= 0.a"
      all = search_for(DepProxy.new base_dep, dependency.__platform).size.to_f
      if all.zero?
        0
      elsif (search = search_for(dependency).size.to_f) == all && all == 1
        0
      else
        search / all
      end
    end
  end
end

def before_resolution
  Bundler.ui.info "Resolving dependencies...", false
end

def debug(depth = 0)
  return unless debug?
  debug_info = yield
  debug_info = debug_info.inspect unless debug_info.is_a?(String)
  STDERR.puts debug_info.split("\n").map {|s| "  " * depth + s }
end

def debug?
  return @debug_mode if defined?(@debug_mode)
  @debug_mode = ENV["DEBUG_RESOLVER"] || ENV["DEBUG_RESOLVER_TREE"]
end

def dependencies_for(specification)
  specification.dependencies_for_activated_platforms
end

def formatted_versions_with_platforms(versions_with_platforms)
  version_platform_strs = versions_with_platforms.map do |vwp|
    version = vwp.first
    platform = vwp.last
    version_platform_str = String.new(version.to_s)
    version_platform_str << " #{platform}" unless platform.nil?
  end
  version_platform_strs.join(", ")
end

def indicate_progress
  Bundler.ui.info ".", false
end

def initialize(index, source_requirements, base, ruby_version)
  @index = index
  @source_requirements = source_requirements
  @base = base
  @resolver = Molinillo::Resolver.new(self, self)
  @search_for = {}
  @base_dg = Molinillo::DependencyGraph.new
  @base.each {|ls| @base_dg.add_vertex(ls.name, Dependency.new(ls.name, ls.version), true) }
  @ruby_version = ruby_version
end

def name_for(dependency)
  dependency.name
end

def name_for_explicit_dependency_source
  Bundler.default_gemfile.basename.to_s
rescue
  "Gemfile"
end

def name_for_locking_dependency_source
  Bundler.default_lockfile.basename.to_s
rescue
  "Gemfile.lock"
end

def requirement_satisfied_by?(requirement, activated, spec)
  requirement.matches_spec?(spec)
end

def search_for(dependency)
  platform = dependency.__platform
  dependency = dependency.dep unless dependency.is_a? Gem::Dependency
  search = @search_for[dependency] ||= begin
    index = @source_requirements[dependency.name] || @index
    results = index.search(dependency, @base[dependency.name])
    if vertex = @base_dg.vertex_named(dependency.name)
      locked_requirement = vertex.payload.requirement
    end
    if results.any?
      version = results.first.version
      nested  = [[]]
      results.each do |spec|
        if spec.version != version
          nested << []
          version = spec.version
        end
        nested.last << spec
      end
      groups = nested.map {|a| SpecGroup.new(a) }
      !locked_requirement ? groups : groups.select {|sg| locked_requirement.satisfied_by? sg.version }
    else
      []
    end
  end
  search.select {|sg| sg.for?(platform, @ruby_version) }.each {|sg| sg.activate_platform(platform) }
end

def sort_dependencies(dependencies, activated, conflicts)
  dependencies.sort_by do |dependency|
    name = name_for(dependency)
    [
      activated.vertex_named(name).payload ? 0 : 1,
      amount_constrained(dependency),
      conflicts[name] ? 0 : 1,
      activated.vertex_named(name).payload ? 0 : search_for(dependency).count,
    ]
  end
end

def start(requirements)
  verify_gemfile_dependencies_are_found!(requirements)
  dg = @resolver.resolve(requirements, @base_dg)
  dg.map(&:payload).map(&:to_specs).flatten
rescue Molinillo::VersionConflict => e
  raise VersionConflict.new(e.conflicts.keys.uniq, e.message)
rescue Molinillo::CircularDependencyError => e
  names = e.dependencies.sort_by(&:name).map {|d| "gem '#{d.name}'" }
  raise CyclicDependencyError, "Your bundle requires gems that depend" \
    " on each other, creating an infinite loop. Please remove" \
    " #{names.count > 1 ? "either " : ""}#{names.join(" or ")}" \
    " and try again."
end

def verify_gemfile_dependencies_are_found!(requirements)
  requirements.each do |requirement|
    next if requirement.name == "bundler"
    next unless search_for(requirement).empty?
    if (base = @base[requirement.name]) && !base.empty?
      version = base.first.version
      message = "You have requested:\n" \
        "  #{requirement.name} #{requirement.requirement}\n\n" \
        "The bundle currently has #{requirement.name} locked at #{version}.\n" \
        "Try running `bundle update #{requirement.name}`\n\n" \
        "If you are updating multiple gems in your Gemfile at once,\n" \
        "try passing them all to `bundle update`"
    elsif requirement.source
      name = requirement.name
      specs = @source_requirements[name][name]
      versions_with_platforms = specs.map {|s| [s.version, s.platform] }
      message = String.new("Could not find gem '#{requirement}' in #{requirement.source}.\n")
      message << if versions_with_platforms.any?
                   "Source contains '#{name}' at: #{formatted_versions_with_platforms(versions_with_platforms)}"
                 else
                   "Source does not contain any versions of '#{requirement}'"
                 end
    else
      message = "Could not find gem '#{requirement}' in any of the gem sources " \
        "listed in your Gemfile or available on this machine."
    end
    raise GemNotFound, message
  end
end