require "simple_xlsx_reader"

class Codinginfo
  CVAR_PREFIX_REGEXP = /^CVAR_[A-Za-z0-9_]+_\d+\./
  PARAM_ASSIGNMENT_HEADERS = { name: /Parameter/, cvar: /Schalter/, package: /Komponente/ }

  class Cvar

    # The CVAR must have a name and _may_ have a package and value
    # the package and value can be merged

    attr_reader :name, :value, :package
    def initialize(name:, package: nil, value: nil)
      @name = name
      @package = package
      @value = value
    end

    def label_prefix
      return /^#{name}_(\w+_)?#{value}\./ if package.nil?

      [name, package, value].join("_") + "."
    end

    def to_s = "#{name}=#{value}"
    def ==(other) = name == other.name

    def merge(other)
      fail "Cannot merge #{name} with #{other.name}" unless self == other

      self.class.new \
        name: name,
        package: package || other.package,
        value: value || other.value
    end
  end

  class Variant
    def initialize(headers, row)
      @properties = headers.zip(row).to_h
    end

    def cvars
      @properties
        .select { |key, _| key.match?(/^CVAR_/) }
        .map { Cvar.new(name: _1, value: _2.to_i) }
    end
  end

  def initialize(ids, filepath)
    @doc         = SimpleXlsxReader.open(filepath)
    @headers     = []
    @variants    = []
    @assignments = {}

    overview_sheet
      .rows
      .each do |row|
        parse_headers(row) if @headers.empty?
        next if @headers.empty?
        next if row[1].nil? || row[3].nil?
        next unless ids.any? { row[1].match?(/#{_1}/i) }
        next unless row[3].match?(/CVAR/)

        @variants << Variant.new(@headers, row)
      end

    param_assignment_sheet
      .rows
      .each(headers: PARAM_ASSIGNMENT_HEADERS) do |row|
        next if row[:cvar].nil?

        @assignments[row[:name]] = Cvar.new(name: row[:cvar], package: row[:package])
      end
  end

  def overview_sheet
    @doc
      .sheets
      .find { _1.name == "Gesamtübersicht" }
      .tap { fail "Cannot find sheet Gesamtübersicht" if _1.nil? }
  end

  def param_assignment_sheet
    @doc
      .sheets
      .find { _1.name == "Parameterdefinition" }
      .tap { fail "Cannot find sheet Parameterdefinition" if _1.nil? }
  end

  def variant
    fail "No variant matching #{id} found!" if @variants.empty?
    fail "More than one variant matching #{id} found!" if @variants.size > 1

    @variants.first
  end

  def unflatten_list(list)
    Ecu::LabelList.new \
      list.flat_map { |label|
        if has_cvar_assignment?(label)
          @variants.map { label.with(name: add_cvar_prefix(label, _1)) }
        else
          label
        end
      }
  end

  def flatten_list(list)
    list
      .select { !cvar_coded?(_1) || has_matching_cvar?(_1) }
      .map_int { _1.with(name: remove_cvar_prefix(_1.name)) }
  end

  def cvar_coded?(label)
    label.name.match?(CVAR_PREFIX_REGEXP)
  end

  def has_cvar_assignment?(label)
    @assignments.key?(label.name)
  end

  def has_matching_cvar?(label)
    variant.cvars.any? { label.name.match?(_1.label_prefix) }
  end

  def add_cvar_prefix(label, variant)
    variant
      .cvars
      .find { _1 == @assignments[label.name] }
      .then { _1.merge(@assignments[label.name]) }
      .then { _1.label_prefix + label.name }
  end

  def remove_cvar_prefix(name)
    name.sub(CVAR_PREFIX_REGEXP, "")
  end

  def parse_headers(row)
    return unless row[1]&.match?(/SWFK-ID/)
    return unless row[1]&.match?(/CVAR_BeguData/)
    return unless row[2]&.match?(/Kommentar/)

    @headers = row
      .map(&:chomp)
      .map(&:lstrip)
      .map(&:strip)
      .map { _1.sub(/\n.*/, "") }
      .tap { _1[0] = "typestr" }
  end
end