using System;
using System.Text.Json;
using Xunit;
using ZB.MOM.WW.CBDDC.Core;
using System.Globalization;

namespace ZB.MOM.WW.CBDDC.Core.Tests
{
    public class OplogEntryTests
    {
        /// <summary>
        /// Verifies that hash computation is deterministic even when payload content differs.
        /// </summary>
        [Fact]
        public void ComputeHash_ShouldBeDeterministic_RegardlessOfPayload()
        {
            // Arrange
            var collection = "test-collection";
            var key = "test-key";
            var op = OperationType.Put;
            var timestamp = new HlcTimestamp(100, 0, "node-1");
            var prevHash = "prev-hash";

            var payload1 = JsonDocument.Parse("{\"prop\": 1}").RootElement;
            var payload2 = JsonDocument.Parse("{\"prop\": 2, \"extra\": \"whitespace\"}").RootElement;

            // Act
            var entry1 = new OplogEntry(collection, key, op, payload1, timestamp, prevHash);
            var entry2 = new OplogEntry(collection, key, op, payload2, timestamp, prevHash);

            // Assert
            entry2.Hash.ShouldBe(entry1.Hash);
        }

        /// <summary>
        /// Verifies that hash computation uses invariant culture formatting for timestamp values.
        /// </summary>
        [Fact]
        public void ComputeHash_ShouldUseInvariantCulture_ForTimestamp()
        {
            // Arrange
            var originalCulture = CultureInfo.CurrentCulture;
            try
            {
                var culture = CultureInfo.GetCultureInfo("de-DE");
                CultureInfo.CurrentCulture = culture;

                var timestamp = new HlcTimestamp(123456789, 1, "node");
                var entry = new OplogEntry("col", "key", OperationType.Put, null, timestamp, "prev");

                // Act
                var hash = entry.ComputeHash();

                // Assert
                CultureInfo.CurrentCulture = CultureInfo.InvariantCulture;
                var expectedEntry = new OplogEntry("col", "key", OperationType.Put, null, timestamp, "prev");
                hash.ShouldBe(expectedEntry.Hash);
            }
            finally
            {
                CultureInfo.CurrentCulture = originalCulture;
            }
        }

        /// <summary>
        /// Verifies that an entry is valid when its stored hash matches computed content.
        /// </summary>
        [Fact]
        public void IsValid_ShouldReturnTrue_WhenHashMatches()
        {
            var timestamp = new HlcTimestamp(100, 0, "node-1");
            var entry = new OplogEntry("col", "key", OperationType.Put, null, timestamp, "prev");

            entry.IsValid().ShouldBeTrue();
        }
    }
}