eccentricity

require 'rubygems'
require 'json'

class Graph
    def initialize(data=nil)
        @graph = data || get_json_data
        @eccentricities = []
    end

    def get_json_data
        file = File.read("graph.json")
        JSON.parse(file)
    end

    def graph_nodes_count
        @graph.keys
    end

    def find_shortest_path(start, finish, travel_path=[])
        travel_path = Array.new(travel_path + start.split)
        return travel_path if (start == finish)
        return nil         if !(@graph.include? start)
        shortest_path = nil
        for node in @graph[start] do
            if (!travel_path.include? node)
                if (new_path = find_shortest_path(node, finish, travel_path))
                    shortest_path = new_path if (!shortest_path || new_path.length < shortest_path.length)
                end
            end
        end
        return shortest_path
    end

    def node_eccentricity(eccentricity, path)
        @eccentricities << eccentricity
        puts "ECCENTRICITY OF PATH: #{path} IS #{eccentricity}"
    end

    def get_radius
        radius = 9999
        for eccentricity in @eccentricities do
            if radius > eccentricity then
                radius = eccentricity
            end
        end
        radius
    end

    def get_diameter
        diameter = 0
        for eccentricity in @eccentricities do
            if diameter < eccentricity then
                diameter = eccentricity
            end
        end
        diameter
    end

    def show_all_eccentricities
        nodes = graph_nodes_count
        for start in nodes do
            max = 0
            max_path = []
            for finish in nodes do
                next if (start == finish)
                path         = find_shortest_path(start, finish)
                eccentricity = path.length

                total = nodes.count + ((nodes.count - 1) * 2) + 2 # ":"
                subtotal = eccentricity + ((eccentricity - 1) * 2)
                tab = " " * (total - subtotal)

                eccentricity -= 1

                for point in path do
                    (path.last == point) ? print("#{point}:#{tab}") : print("#{point}->") # Paths list
                end
                if (path && max < eccentricity) then
                    max      = eccentricity
                    max_path = path
                end
                puts max
            end
            puts
            # puts max # and steps count
            node_eccentricity(max, max_path)
        end
    end
end

data = {'A'=> ['B', 'C'],
        'B'=> ['A', 'C', 'D'],
        'C'=> ['A', 'B', 'D', 'F'],
        'D'=> ['B', 'C'],
        'E'=> ['C', 'F'],
        'F'=> ['C', 'E']
}

graph = Graph.new()
graph.show_all_eccentricities
p graph.get_radius
p graph.get_diameter