using System;
using System.Collections.Generic;
using System.IO;

namespace DCIT.Core.Utilities
{
    public static class PathUtility
    {
        public static string NormalizeDirectory(string path)
        {
            if (string.IsNullOrWhiteSpace(path))
            {
                return string.Empty;
            }

            var fullPath = Path.GetFullPath(path.Trim());
            if (!fullPath.EndsWith(Path.DirectorySeparatorChar.ToString(), StringComparison.Ordinal))
            {
                fullPath += Path.DirectorySeparatorChar;
            }

            return fullPath;
        }

        public static bool AreSameOrNestedDirectories(string left, string right)
        {
            var normalizedLeft = NormalizeDirectory(left);
            var normalizedRight = NormalizeDirectory(right);
            if (string.IsNullOrEmpty(normalizedLeft) || string.IsNullOrEmpty(normalizedRight))
            {
                return false;
            }

            return normalizedLeft.Equals(normalizedRight, StringComparison.OrdinalIgnoreCase)
                || normalizedLeft.StartsWith(normalizedRight, StringComparison.OrdinalIgnoreCase)
                || normalizedRight.StartsWith(normalizedLeft, StringComparison.OrdinalIgnoreCase);
        }

        public static string GetRelativePath(string relativeTo, string path)
        {
            var root = new Uri(NormalizeDirectory(relativeTo), UriKind.Absolute);
            var target = new Uri(Path.GetFullPath(path), UriKind.Absolute);
            var relative = root.MakeRelativeUri(target).ToString().Replace('/', Path.DirectorySeparatorChar);
            return Uri.UnescapeDataString(relative);
        }

        public static IEnumerable<string> ValidateDirectoryPair(string firstLabel, string firstPath, string secondLabel, string secondPath)
        {
            if (string.IsNullOrWhiteSpace(firstPath) || string.IsNullOrWhiteSpace(secondPath))
            {
                yield break;
            }

            if (AreSameOrNestedDirectories(firstPath, secondPath))
            {
                yield return string.Format("{0} 与 {1} 不能相同，也不能互为父子目录。", firstLabel, secondLabel);
            }
        }
    }
}