using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Packager.Parameters;
using Ubisoft.P4API.Exceptions;

namespace Packager.Tasks
{
    public class MergeMapDependenciesTask : Task
    {
        /// <summary>
        /// Collection of paths.
        /// </summary>
        [Input(nameof(FilePaths), IOCardinality.Multi, IOType.File)]
        public ReferenceList FilePaths { get; set; }

        /// <summary>
        /// Collection of paths to files containing the dependencies of each map.
        /// </summary>
        [Output(nameof(MergedMapDependenciesFilePaths), IOType.File)]
        public ReferenceList MergedMapDependenciesFilePaths = new ReferenceList();

        public MergeMapDependenciesTask()
        {
            FilePaths = new ReferenceList();
        }

        protected override void StartInternal(BuildConfiguration profile, cookerWrapper cooker)
        {
            Dictionary<string, HashSet<string> > mapsDependencies = new Dictionary<string, HashSet<string>>();

            foreach (string filePath in FilePaths)
            {
                if (!File.Exists(filePath))
                {
                    throw new FileNotFoundException($"Input file was not found at \"{filePath}\".");
                }
                
                string fileName = Path.GetFileName(filePath) ?? string.Empty;
                int underscoreIndex = fileName.IndexOf('_');
                if (underscoreIndex < 0)
                {
                    throw new ArgumentException($"Unable to find character '_' in filename '{fileName}' from path \"{filePath}\".");
                }
                
                string mapName = fileName.Remove(underscoreIndex);

                Logger.LogInfo($"File \'{filePath}\' belongs to map \'{mapName}\'.");

                if (!mapsDependencies.ContainsKey(mapName))
                {
                    mapsDependencies.Add(mapName, new HashSet<string>());
                }

                mapsDependencies[mapName].Add(filePath);
            }

            foreach (string mapName in mapsDependencies.Keys)
            {
                HashSet<string> mapFiles = mapsDependencies[mapName];

                IEnumerable<string> filesLines = mapFiles.SelectMany(File.ReadAllLines).Where(line => !string.IsNullOrWhiteSpace(line));
                string mergedFileContent = string.Join(Environment.NewLine, filesLines);

                string mergedFilename = $"{mapName}_merged_dependencies.txt";
                string mergedFilePath = Path.Combine(TaskOutputFolder, mergedFilename);
                
                File.WriteAllText(mergedFilePath, mergedFileContent);

                Logger.LogInfo($"Wrote {mapName} dependencies to \'{mergedFilePath}\'.");

                MergedMapDependenciesFilePaths.Add(mergedFilePath);
            }
        }
    }
}