using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Graph = NetworkFlow.Graph;

namespace Program
{
    class Program
    {
        static void Main(string[] args)
        {
            // attempt to read file from command line args, otherwise asks for a file
            FileInfo inputFile = (args.Length > 0) ? new FileInfo(args[0]) : ReadFileName();

            // attempt to get source and terminal nodes from command line args
            string source = (args.Length >= 2) ? args[1] : default(string);
            string terminal = (args.Length >= 3) ? args[2] : default(string);


            if (!inputFile.Exists)
            {
                Console.WriteLine($"Failed to open {inputFile}: File does not exist.");
                return;
            }

            // read file into graph
            Graph graph = ReadFile(inputFile.FullName);

            // verify command line source and terminal values or gets new values from the user
            (int s, int t) = ReadSourceAndTerminal(graph, source, terminal);

            // call maxFlow
            double maxFlow = graph.MaxFlow(s, t);
            Console.WriteLine($"The max flow is {maxFlow}");
        }

        public static (int s, int t) ReadSourceAndTerminal(Graph graph, string source, string terminal)
        {
            int s, t;
            // retries until it succeeds
            while (true)
            {
                // try to parse supplied values
                bool isSetSource = int.TryParse(source, out s);
                bool isSetTerminal = int.TryParse(terminal, out t);

                // validates the values are ints and the graph contains the corresponding node
                if (!(isSetSource && graph.Nodes.ContainsKey(s)))
                {
                    if (source != default(string))
                        Console.WriteLine($"Invalid Source Node: {source}");
                    Console.Write($"Enter the Source Node: ");
                    // asks for a new value
                    source = Console.ReadLine();
                }
                // validates the values are ints and the graph contains the corresponding node
                if (!(isSetTerminal && graph.Nodes.ContainsKey(t)))
                {
                    if (terminal != default(string))
                        Console.WriteLine($"Invalid Terminal Node: {terminal}");
                    Console.Write($"Enter the Terminal Node: ");
                    // asks for a new value
                    terminal = Console.ReadLine();
                }
                // if everything is correct then we can return
                if (isSetSource && isSetTerminal && graph.Nodes.ContainsKey(s) && graph.Nodes.ContainsKey(t))
                    break;
            }


            return (s, t);
        }

        public static FileInfo ReadFileName()
        {
            string filePath;

            // continues to ask for a valid filepath until obtained
            while (true)
            {
                Console.Write("Enter a path to a points file: ");
                filePath = Console.ReadLine();

                if (String.IsNullOrEmpty(filePath))
                    Console.WriteLine("File path cannot be empty!");
                else if (!System.IO.File.Exists(filePath))
                    Console.WriteLine($"{filePath} does not exist.");
                else
                    break;
            }

            FileInfo file = new FileInfo(filePath);

            return file;
        }

        public static Graph ReadFile(string file)
        {
            // create default Graph object
            Graph graph = new Graph();

            // Read in graph file
            foreach (string line in File.ReadLines(file))
            {
                // each file line is a Node with optional edges
                // line format:
                // vertex:int optional[ connected-vertex:int edge-weight:double optional[..] ]
                List<string> vals = line.Split(' ').ToList();
                int u, v;
                double weight;
                int.TryParse(vals[0], out u);
                graph.AddNode(u);
                for (int i = 1; i < vals.Count - 1; i += 2)
                {
                    // AddEdge(int u, int v, double weight)
                    int.TryParse(vals[i], out v);
                    double.TryParse(vals[i + 1], out weight);
                    graph.AddEdge(u, v, weight);
                }
            }
            // return object when done
            return graph;
        }
    }
}