// Copyright (c) Microsoft. All rights reserved.

using System;
using System.Collections.Generic;
using Microsoft.Extensions.VectorData;
using Microsoft.Extensions.VectorData.ProviderServices;
using Microsoft.SemanticKernel.Connectors.PgVector;
using NpgsqlTypes;
using Pgvector;
using Xunit;

namespace SemanticKernel.Connectors.PgVector.UnitTests;

/// <summary>
/// Unit tests for <see cref="PostgresPropertyMapping"/> class.
/// </summary>
public sealed class PostgresPropertyMappingTests
{
    [Fact]
    public void MapVectorForStorageModelWithInvalidVectorTypeThrowsException()
    {
        // Arrange
        var vector = new List<float> { 1f, 2f, 3f };

        // Act & Assert
        Assert.Throws<NotSupportedException>(() => PostgresPropertyMapping.MapVectorForStorageModel(vector));
    }

    [Fact]
    public void MapVectorForStorageModelReturnsVector()
    {
        // Arrange
        var vector = new ReadOnlyMemory<float>([1.1f, 2.2f, 3.3f, 4.4f]);

        // Act
        var storageModelVector = PostgresPropertyMapping.MapVectorForStorageModel(vector);

        // Assert
        var actual = Assert.IsType<Vector>(storageModelVector);
        Assert.True(actual.ToArray().Length > 0);
    }

    [Fact]
    public void GetPropertyValueReturnsCorrectValuesForLists()
    {
        // Arrange
        var typesAndExpectedValues = new List<(Type, object)>
        {
            (typeof(List<int>), "INTEGER[]"),
            (typeof(List<float>), "REAL[]"),
            (typeof(List<double>), "DOUBLE PRECISION[]"),
            (typeof(List<string>), "TEXT[]"),
            (typeof(List<bool>), "BOOLEAN[]"),
            (typeof(List<DateTime>), "TIMESTAMPTZ[]"),
            (typeof(List<Guid>), "UUID[]"),
        };

        // Act & Assert
        foreach (var (type, expectedValue) in typesAndExpectedValues)
        {
            var property = new DataPropertyModel("test", type);
            var (pgType, _) = PostgresPropertyMapping.GetPostgresTypeName(property);
            Assert.Equal(expectedValue, pgType);
        }
    }

    [Fact]
    public void GetPropertyValueReturnsCorrectNullableValue()
    {
        // Arrange
        var typesAndExpectedValues = new List<(Type, object)>
        {
            (typeof(short), false),
            (typeof(short?), true),
            (typeof(int?), true),
            (typeof(long), false),
            (typeof(string), true),
            (typeof(bool?), true),
            (typeof(DateTime?), true),
            (typeof(Guid), false),
        };

        // Act & Assert
        foreach (var (type, expectedValue) in typesAndExpectedValues)
        {
            var property = new DataPropertyModel("test", type);
            var (_, isNullable) = PostgresPropertyMapping.GetPostgresTypeName(property);
            Assert.Equal(expectedValue, isNullable);
        }
    }

    [Fact]
    public void GetIndexInfoReturnsCorrectValues()
    {
        // Arrange
        List<PropertyModel> vectorProperties =
        [
            new VectorPropertyModel("vector1", typeof(ReadOnlyMemory<float>?)) { IndexKind = IndexKind.Hnsw, Dimensions = 1000 },
            new VectorPropertyModel("vector2", typeof(ReadOnlyMemory<float>?)) { IndexKind = IndexKind.Flat, Dimensions = 3000 },
            new VectorPropertyModel("vector3", typeof(ReadOnlyMemory<float>?)) { IndexKind = IndexKind.Hnsw, Dimensions = 900, DistanceFunction = DistanceFunction.ManhattanDistance },
            new DataPropertyModel("data1", typeof(string)) { IsIndexed = true },
            new DataPropertyModel("data2", typeof(string)) { IsIndexed = false }
        ];

        // Act
        var indexInfo = PostgresPropertyMapping.GetIndexInfo(vectorProperties);

        // Assert
        Assert.Equal(3, indexInfo.Count);
        foreach (var (columnName, indexKind, distanceFunction, isVector, isFullText, fullTextLanguage) in indexInfo)
        {
            if (columnName == "vector1")
            {
                Assert.True(isVector);
                Assert.False(isFullText);
                Assert.Equal(IndexKind.Hnsw, indexKind);
                Assert.Equal(DistanceFunction.CosineDistance, distanceFunction);
            }
            else if (columnName == "vector3")
            {
                Assert.True(isVector);
                Assert.False(isFullText);
                Assert.Equal(IndexKind.Hnsw, indexKind);
                Assert.Equal(DistanceFunction.ManhattanDistance, distanceFunction);
            }
            else if (columnName == "data1")
            {
                Assert.False(isVector);
                Assert.False(isFullText);
            }
            else
            {
                Assert.Fail("Unexpected column name");
            }
        }
    }

    [Theory]
    [InlineData(IndexKind.Hnsw, 3000)]
    public void GetVectorIndexInfoReturnsThrowsForInvalidDimensions(string indexKind, int dimensions)
    {
        // Arrange
        var vectorProperty = new VectorPropertyModel("vector", typeof(ReadOnlyMemory<float>?)) { IndexKind = indexKind, Dimensions = dimensions };

        // Act & Assert
        Assert.Throws<NotSupportedException>(() => PostgresPropertyMapping.GetIndexInfo([vectorProperty]));
    }

    [Fact]
    public void GetPostgresTypeName_DateTime_WithTimestampAnnotation_ReturnsTimestamp()
    {
        var dataProperty = new DataPropertyModel("created", typeof(DateTime));
        dataProperty.ProviderAnnotations = new() { ["Postgres:StoreType"] = "timestamp" };

        var (pgType, _) = PostgresPropertyMapping.GetPostgresTypeName(dataProperty);
        Assert.Equal("TIMESTAMP", pgType);
    }

    [Fact]
    public void GetPostgresTypeName_DateTime_WithoutAnnotation_ReturnsTimestampTz()
    {
        var dataProperty = new DataPropertyModel("created", typeof(DateTime));

        var (pgType, _) = PostgresPropertyMapping.GetPostgresTypeName(dataProperty);
        Assert.Equal("TIMESTAMPTZ", pgType);
    }

    [Fact]
    public void GetPostgresTypeName_NullableDateTime_WithTimestampAnnotation_ReturnsTimestamp()
    {
        var dataProperty = new DataPropertyModel("created", typeof(DateTime?));
        dataProperty.ProviderAnnotations = new() { ["Postgres:StoreType"] = "timestamp" };

        var (pgType, isNullable) = PostgresPropertyMapping.GetPostgresTypeName(dataProperty);
        Assert.Equal("TIMESTAMP", pgType);
        Assert.True(isNullable);
    }

    [Fact]
    public void GetNpgsqlDbType_DateTime_WithTimestampAnnotation_ReturnsTimestamp()
    {
        var dataProperty = new DataPropertyModel("created", typeof(DateTime));
        dataProperty.ProviderAnnotations = new() { ["Postgres:StoreType"] = "timestamp" };

        var dbType = PostgresPropertyMapping.GetNpgsqlDbType(dataProperty);
        Assert.Equal(NpgsqlDbType.Timestamp, dbType);
    }

    [Fact]
    public void GetNpgsqlDbType_DateTime_WithoutAnnotation_ReturnsTimestampTz()
    {
        var dataProperty = new DataPropertyModel("created", typeof(DateTime));

        var dbType = PostgresPropertyMapping.GetNpgsqlDbType(dataProperty);
        Assert.Equal(NpgsqlDbType.TimestampTz, dbType);
    }
}