require 'uri'
require 'json'
require 'set'
require 'semantic_puppet/version'

module PuppetForge
  module V3
    # This class provides a data structure representing a module's metadata.
    # @api private
    class Metadata

      attr_accessor :module_name

      DEFAULTS = {
        'name'         => nil,
        'version'      => nil,
        'author'       => nil,
        'summary'      => nil,
        'license'      => 'Apache-2.0',
        'source'       => '',
        'project_page' => nil,
        'issues_url'   => nil,
        'dependencies' => Set.new.freeze,
      }

      def initialize
        @data = DEFAULTS.dup
        @data['dependencies'] = @data['dependencies'].dup
      end

      # Returns a filesystem-friendly version of this module name.
      def dashed_name
        PuppetForge::V3.normalize_name(@data['name']) if @data['name']
      end

      # Returns a string that uniquely represents this version of this module.
      def release_name
        return nil unless @data['name'] && @data['version']
        [ dashed_name, @data['version'] ].join('-')
      end

      alias :name :module_name
      alias :full_module_name :dashed_name

      # Merges the current set of metadata with another metadata hash.  This
      # method also handles the validation of module names and versions, in an
      # effort to be proactive about module publishing constraints.
      def update(data, with_dependencies = true)
        process_name(data) if data['name']
        process_version(data) if data['version']
        process_source(data) if data['source']
        merge_dependencies(data) if with_dependencies && data['dependencies']

        @data.merge!(data)
        return self
      end

      # Validates the name and version_requirement for a dependency, then creates
      # the Dependency and adds it.
      # Returns the Dependency that was added.
      def add_dependency(name, version_requirement=nil, repository=nil)
        validate_name(name)
        validate_version_range(version_requirement) if version_requirement

        if dup = @data['dependencies'].find { |d| d.full_module_name == name && d.version_requirement != version_requirement }
          raise ArgumentError, "Dependency conflict for #{full_module_name}: Dependency #{name} was given conflicting version requirements #{version_requirement} and #{dup.version_requirement}. Verify that there are no duplicates in the metadata.json or the Modulefile."
        end

        dep = Dependency.new(name, version_requirement, repository)
        @data['dependencies'].add(dep)

        dep
      end

      # Provides an accessor for the now defunct 'description' property.  This
      # addresses a regression in Puppet 3.6.x where previously valid templates
      # refering to the 'description' property were broken.
      # @deprecated
      def description
        @data['description']
      end

      def dependencies
        @data['dependencies'].to_a
      end

      # Returns a hash of the module's metadata.  Used by Puppet's automated
      # serialization routines.
      #
      # @see Puppet::Network::FormatSupport#to_data_hash
      def to_hash
        @data
      end
      alias :to_data_hash :to_hash

      def to_json
        data = @data.dup.merge('dependencies' => dependencies)

        contents = data.keys.map do |k|
          value = (JSON.pretty_generate(data[k]) rescue data[k].to_json)
          "#{k.to_json}: #{value}"
        end

        "{\n" + contents.join(",\n").gsub(/^/, '  ') + "\n}\n"
      end

      # Expose any metadata keys as callable reader methods.
      def method_missing(name, *args)
        return @data[name.to_s] if @data.key? name.to_s
        super
      end

      private

      # Do basic validation and parsing of the name parameter.
      def process_name(data)
        validate_name(data['name'])
        author, @module_name = data['name'].split(/[-\/]/, 2)

        data['author'] ||= author if @data['author'] == DEFAULTS['author']
      end

      # Do basic validation on the version parameter.
      def process_version(data)
        validate_version(data['version'])
      end

      # Do basic parsing of the source parameter.  If the source is hosted on
      # GitHub, we can predict sensible defaults for both project_page and
      # issues_url.
      def process_source(data)
        if data['source'] =~ %r[://]
          source_uri = URI.parse(data['source'])
        else
          source_uri = URI.parse("http://#{data['source']}")
        end

        if source_uri.host =~ /^(www\.)?github\.com$/
          source_uri.scheme = 'https'
          source_uri.path.sub!(/\.git$/, '')
          data['project_page'] ||= @data['project_page'] || source_uri.to_s
          data['issues_url'] ||= @data['issues_url'] || source_uri.to_s.sub(/\/*$/, '') + '/issues'
        end

      rescue URI::Error
        return
      end

      # Validates and parses the dependencies.
      def merge_dependencies(data)
        data['dependencies'].each do |dep|
          add_dependency(dep['name'], dep['version_requirement'], dep['repository'])
        end

        # Clear dependencies so @data dependencies are not overwritten
        data.delete 'dependencies'
      end

      # Validates that the given module name is both namespaced and well-formed.
      def validate_name(name)
        return if name =~ /\A[a-z0-9]+[-\/][a-z][a-z0-9_]*\Z/i

        namespace, modname = name.split(/[-\/]/, 2)
        modname = :namespace_missing if namespace == ''

        err = case modname
        when nil, '', :namespace_missing
          "the field must be a namespaced module name"
        when /[^a-z0-9_]/i
          "the module name contains non-alphanumeric (or underscore) characters"
        when /^[^a-z]/i
          "the module name must begin with a letter"
        else
          "the namespace contains non-alphanumeric characters"
        end

        raise ArgumentError, "Invalid 'name' field in metadata.json: #{err}"
      end

      # Validates that the version string can be parsed by SemanticPuppet.
      def validate_version(version)
        return if SemanticPuppet::Version.valid?(version)

        err = "version string cannot be parsed as a valid Semantic Version"
        raise ArgumentError, "Invalid 'version' field in metadata.json: #{err}"
      end

      # Validates that the version range can be parsed by SemanticPuppet.
      def validate_version_range(version_range)
        SemanticPuppet::VersionRange.parse(version_range)
      rescue ArgumentError => e
        raise ArgumentError, "Invalid 'version_range' field in metadata.json: #{e}"
      end
    end
  end
end