# frozen_string_literal: true

require "json"

module Floe
  class Workflow
    class << self
      def load(path_or_io, context = {}, credentials = {})
        payload = path_or_io.respond_to?(:read) ? path_or_io.read : File.read(path_or_io)
        new(payload, context, credentials)
      end
    end

    attr_reader :context, :credentials, :first_state, :payload, :states, :states_by_name, :start_at

    def initialize(payload, context = {}, credentials = {})
      payload     = JSON.parse(payload)     if payload.kind_of?(String)
      context     = JSON.parse(context)     if context.kind_of?(String)
      credentials = JSON.parse(credentials) if credentials.kind_of?(String)

      @payload        = payload
      @context        = context
      @credentials    = credentials
      @states         = payload["States"].to_a.map { |name, state| State.build!(self, name, state) }
      @states_by_name = states.to_h { |state| [state.name, state] }
      @start_at       = @payload["StartAt"]
      @first_state    = @states_by_name[@start_at]
    rescue JSON::ParserError => err
      raise Floe::InvalidWorkflowError, err.message
    end

    def run!
      state = first_state
      input = context.dup

      until state.nil?
        state, output = state.run!(input)
        input = output
      end

      output
    end

    def to_dot
      String.new.tap do |s|
        s << "digraph {\n"
        states.each do |state|
          s << state.to_dot << "\n"
        end
        s << "\n"
        states.each do |state|
          Array(state.to_dot_transitions).each do |transition|
            s << transition << "\n"
          end
        end
        s << "}\n"
      end
    end

    def to_svg(path: nil)
      require "open3"
      out, err, _status = Open3.capture3("dot -Tsvg", :stdin_data => to_dot)

      raise "Error from graphviz:\n#{err}" if err && !err.empty?

      File.write(path, out) if path

      out
    end

    def to_ascii(path: nil)
      require "open3"
      out, err, _status = Open3.capture3("graph-easy", :stdin_data => to_dot)

      raise "Error from graph-easy:\n#{err}" if err && !err.empty?

      File.write(path, out) if path

      out
    end
  end
end