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 *
 * OPC Foundation MIT License 1.00
 *
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 * obtaining a copy of this software and associated documentation
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using System;
using NUnit.Framework;
using Opc.Ua.Client.FileSystem;

namespace Opc.Ua.Client.Tests.FileSystem
{
    /// <summary>
    /// Unit tests for <see cref="UaPath"/>.
    /// </summary>
    [TestFixture]
    [Category("FileSystem")]
    [SetCulture("en-us")]
    [SetUICulture("en-us")]
    [Parallelizable]
    public class UaPathTests
    {
        [Test]
        public void ParseEmptyReturnsEmptyArray()
        {
            Assert.That(UaPath.Parse(string.Empty), Is.Empty);
        }

        [Test]
        public void ParseRootReturnsEmptyArray()
        {
            Assert.That(UaPath.Parse("/"), Is.Empty);
        }

        [Test]
        public void ParseSingleSegmentReturnsOneEntry()
        {
            QualifiedName[] segments = UaPath.Parse("foo");
            Assert.That(segments, Has.Length.EqualTo(1));
            Assert.That(segments[0].Name, Is.EqualTo("foo"));
            Assert.That(segments[0].NamespaceIndex, Is.Zero);
        }

        [Test]
        public void ParseLeadingAndTrailingSlashesAreTolerated()
        {
            QualifiedName[] segments = UaPath.Parse("/foo/bar/");
            Assert.That(segments, Has.Length.EqualTo(2));
            Assert.That(segments[0].Name, Is.EqualTo("foo"));
            Assert.That(segments[1].Name, Is.EqualTo("bar"));
        }

        [Test]
        public void ParseQualifiedSegmentRetainsNamespaceIndex()
        {
            QualifiedName[] segments = UaPath.Parse("1:Reports/2:2024/data.csv");
            Assert.That(segments, Has.Length.EqualTo(3));
            Assert.That(segments[0].NamespaceIndex, Is.EqualTo(1));
            Assert.That(segments[0].Name, Is.EqualTo("Reports"));
            Assert.That(segments[1].NamespaceIndex, Is.EqualTo(2));
            Assert.That(segments[1].Name, Is.EqualTo("2024"));
            Assert.That(segments[2].NamespaceIndex, Is.Zero);
            Assert.That(segments[2].Name, Is.EqualTo("data.csv"));
        }

        [Test]
        public void ParseEmptyMiddleSegmentThrows()
        {
            ArgumentException ex = Assert.Throws<ArgumentException>(
                () => UaPath.Parse("foo//bar"));
            Assert.That(ex.Message, Does.Contain("empty segment"));
        }

        [Test]
        public void ParseInvalidNamespacePrefixThrows()
        {
            ArgumentException ex = Assert.Throws<ArgumentException>(
                () => UaPath.Parse("abc:foo"));
            Assert.That(ex.Message, Does.Contain("non-numeric"));
        }

        [Test]
        public void ParseEmptyNamespacePrefixThrows()
        {
            Assert.Throws<ArgumentException>(() => UaPath.Parse(":foo"));
        }

        [Test]
        public void ParseEmptyNameAfterNamespacePrefixThrows()
        {
            Assert.Throws<ArgumentException>(() => UaPath.Parse("1:"));
        }

        [Test]
        public void ParseNullThrowsArgumentNullException()
        {
            Assert.Throws<ArgumentNullException>(() => UaPath.Parse(null!));
        }

        [Test]
        public void FormatEmptyReturnsRoot()
        {
            Assert.That(UaPath.Format([]), Is.EqualTo("/"));
        }

        [Test]
        public void FormatPreservesNamespaceIndex()
        {
            string formatted = UaPath.Format(
            [
                new QualifiedName("Reports", 1),
                new QualifiedName("2024", 2),
                new QualifiedName("data.csv")
            ]);
            Assert.That(formatted, Is.EqualTo("/1:Reports/2:2024/data.csv"));
        }

        [Test]
        public void FormatRoundTripsThroughParse()
        {
            const string original = "/1:Reports/2:2024/data.csv";
            string roundTripped = UaPath.Format(UaPath.Parse(original));
            Assert.That(roundTripped, Is.EqualTo(original));
        }

        [Test]
        public void FormatEscapesReservedCharactersAndRoundTrips()
        {
            QualifiedName[] segments =
            [
                new QualifiedName("12:30.log"),
                new QualifiedName("a/b"),
                new QualifiedName("x&:y", 2),
                new QualifiedName("a&b"),
                new QualifiedName("c:d")
            ];

            string formatted = UaPath.Format(segments);

            Assert.That(formatted, Is.EqualTo("/12&:30.log/a&/b/2:x&&&:y/a&b/c&:d"));
            Assert.That(UaPath.Parse(formatted), Is.EqualTo(segments));
        }

        /// <summary>
        /// Review G12: Format and Parse round-trip names ending in '&amp;'
        /// (as a middle or final segment) and a final name ending in '/'.
        /// </summary>
        [TestCase("Q&")]
        [TestCase("a&b")]
        [TestCase("&")]
        [TestCase("x/")]
        [TestCase("12:30.log")]
        [TestCase("&&/")]
        [TestCase("&&")]
        [TestCase("/")]
        [TestCase("a&:")]
        public void FormatParseRoundTripsTrickyNames(string name)
        {
            QualifiedName[][] paths =
            [
                [new QualifiedName(name)],
                [new QualifiedName(name), new QualifiedName("x")],
                [new QualifiedName("x"), new QualifiedName(name)],
                [new QualifiedName(name, 3), new QualifiedName(name)],
                [new QualifiedName(name), new QualifiedName(name, 2)]
            ];

            foreach (QualifiedName[] segments in paths)
            {
                string formatted = UaPath.Format(segments);
                Assert.That(UaPath.Parse(formatted), Is.EqualTo(segments), formatted);
                Assert.That(UaPath.Normalize(formatted), Is.EqualTo(formatted));
            }
        }

        [Test]
        public void FormatEscapesTrailingAmpersandBeforeSeparator()
        {
            QualifiedName[] segments = [new QualifiedName("Q&"), new QualifiedName("x")];

            Assert.That(UaPath.Format(segments), Is.EqualTo("/Q&&/x"));
            Assert.That(UaPath.Parse("/Q&&/x"), Is.EqualTo(segments));
        }

        [Test]
        public void ParseKeepsEscapedFinalSeparatorAndTrimsUnescapedOne()
        {
            Assert.That(UaPath.Parse("/x&/"), Is.EqualTo(new[] { new QualifiedName("x/") }));
            Assert.That(UaPath.Parse("/x&&/"), Is.EqualTo(new[] { new QualifiedName("x&") }));
            Assert.That(UaPath.Parse("/a/b/"), Is.EqualTo(new[] { new QualifiedName("a"), new QualifiedName("b") }));
            // An '&' at the very end with nothing to escape stays literal.
            Assert.That(UaPath.Parse("/Q&"), Is.EqualTo(new[] { new QualifiedName("Q&") }));
        }

        [Test]
        public void ParseTreatsAmpersandBeforeOrdinaryCharacterAsLiteral()
        {
            QualifiedName[] segments = UaPath.Parse("/R&D/a&b");
            Assert.That(segments[0], Is.EqualTo(new QualifiedName("R&D")));
            Assert.That(segments[1], Is.EqualTo(new QualifiedName("a&b")));
        }

        [Test]
        public void FormatSegmentNs0OmitsPrefix()
        {
            Assert.That(
                UaPath.FormatSegment(new QualifiedName("foo")),
                Is.EqualTo("foo"));
        }

        [Test]
        public void FormatSegmentNs1IncludesPrefix()
        {
            Assert.That(
                UaPath.FormatSegment(new QualifiedName("foo", 1)),
                Is.EqualTo("1:foo"));
        }

        [Test]
        public void FormatSegmentEmptyNameThrows()
        {
            Assert.Throws<ArgumentException>(
                () => UaPath.FormatSegment(QualifiedName.Null));
        }

        [Test]
        public void CombineWithRelativeRightAppends()
        {
            Assert.That(
                UaPath.Combine("/foo", "bar"),
                Is.EqualTo("/foo/bar"));
        }

        [Test]
        public void CombineWithAbsoluteRightReplacesLeft()
        {
            Assert.That(
                UaPath.Combine("/foo", "/baz/qux"),
                Is.EqualTo("/baz/qux"));
        }

        [Test]
        public void CombineNullLeftIsRoot()
        {
            Assert.That(
                UaPath.Combine(null!, "bar"),
                Is.EqualTo("/bar"));
        }

        [Test]
        public void CombineEmptyRightReturnsLeft()
        {
            Assert.That(
                UaPath.Combine("/foo", string.Empty),
                Is.EqualTo("/foo"));
        }

        [Test]
        public void CombineNullRightThrows()
        {
            Assert.Throws<ArgumentNullException>(
                () => UaPath.Combine("/foo", null!));
        }

        [Test]
        public void GetDirectoryNameOfRootReturnsNull()
        {
            Assert.That(UaPath.GetDirectoryName("/"), Is.Null);
        }

        [Test]
        public void GetDirectoryNameOfSingleSegmentReturnsRoot()
        {
            Assert.That(UaPath.GetDirectoryName("foo"), Is.EqualTo("/"));
        }

        [Test]
        public void GetDirectoryNameOfMultipleSegmentsReturnsParent()
        {
            Assert.That(
                UaPath.GetDirectoryName("/1:Reports/2024/data.csv"),
                Is.EqualTo("/1:Reports/2024"));
        }

        [Test]
        public void GetFileNameOfRootReturnsNullQualifiedName()
        {
            Assert.That(UaPath.GetFileName("/").IsNull, Is.True);
        }

        [Test]
        public void GetFileNameReturnsLeafSegment()
        {
            QualifiedName name = UaPath.GetFileName("/1:Reports/2024/data.csv");
            Assert.That(name.NamespaceIndex, Is.Zero);
            Assert.That(name.Name, Is.EqualTo("data.csv"));
        }

        [Test]
        public void NormalizeAddsLeadingSlashAndStripsTrailing()
        {
            Assert.That(UaPath.Normalize("foo/bar/"), Is.EqualTo("/foo/bar"));
        }

        [Test]
        public void NamespacedSiblingsProduceDistinctCanonicalPaths()
        {
            string a = UaPath.Format([new QualifiedName("foo", 1)]);
            string b = UaPath.Format([new QualifiedName("foo", 2)]);
            Assert.That(a, Is.Not.EqualTo(b));
        }
    }
}