using JdeScoping.DataSync.Models;
using JdeScoping.DataSync.Services;

namespace JdeScoping.DataSync.Tests.Services;

public class SchemaValidatorTests
{
    private readonly SchemaValidator _validator = new();

    private class TestEntity
    {
        public int Id { get; set; }
        public string Name { get; set; } = string.Empty;
        public string? NullableName { get; set; }
        public decimal Amount { get; set; }
        public DateTime CreatedDate { get; set; }
    }

    #region ValidateBatch Tests

    [Fact]
    public void ValidateBatch_EmptyData_ReturnsEmptyList()
    {
        // Arrange
        var data = Array.Empty<TestEntity>();
        var schema = new List<ColumnSchema>
        {
            new("Id", "int", null, 10, 0, false, 1)
        };

        // Act
        var errors = _validator.ValidateBatch(data, schema);

        // Assert
        Assert.Empty(errors);
    }

    [Fact]
    public void ValidateBatch_EmptySchema_ReturnsEmptyList()
    {
        // Arrange
        var data = new List<TestEntity> { new() { Id = 1, Name = "Test" } };
        var schema = Array.Empty<ColumnSchema>();

        // Act
        var errors = _validator.ValidateBatch(data, schema);

        // Assert
        Assert.Empty(errors);
    }

    [Fact]
    public void ValidateBatch_ValidData_ReturnsEmptyList()
    {
        // Arrange
        var data = new List<TestEntity>
        {
            new() { Id = 1, Name = "Test", Amount = 100.50m }
        };
        var schema = new List<ColumnSchema>
        {
            new("Id", "int", null, 10, 0, false, 1),
            new("Name", "nvarchar", 50, null, null, false, 2),
            new("Amount", "decimal", null, 10, 2, false, 3)
        };

        // Act
        var errors = _validator.ValidateBatch(data, schema);

        // Assert
        Assert.Empty(errors);
    }

    [Fact]
    public void ValidateBatch_StringTooLong_ReturnsError()
    {
        // Arrange
        var data = new List<TestEntity>
        {
            new() { Id = 1, Name = "This is a very long string that exceeds the maximum length" }
        };
        var schema = new List<ColumnSchema>
        {
            new("Id", "int", null, 10, 0, false, 1),
            new("Name", "nvarchar", 10, null, null, false, 2)
        };

        // Act
        var errors = _validator.ValidateBatch(data, schema);

        // Assert
        Assert.Single(errors);
        Assert.Equal("Name", errors[0].ColumnName);
        Assert.Equal(0, errors[0].RowIndex);
        Assert.Contains("exceeds maximum length", errors[0].Message);
    }

    [Fact]
    public void ValidateBatch_NullInNonNullableColumn_ReturnsError()
    {
        // Arrange
        var data = new List<TestEntity>
        {
            new() { Id = 1, Name = "" } // Empty string treated as null for non-nullable
        };
        var schema = new List<ColumnSchema>
        {
            new("Id", "int", null, 10, 0, false, 1),
            new("Name", "nvarchar", 50, null, null, false, 2)
        };

        // Act
        var errors = _validator.ValidateBatch(data, schema);

        // Assert
        Assert.Single(errors);
        Assert.Equal("Name", errors[0].ColumnName);
        Assert.Contains("does not allow null", errors[0].Message);
    }

    [Fact]
    public void ValidateBatch_NullInNullableColumn_NoError()
    {
        // Arrange
        var data = new List<TestEntity>
        {
            new() { Id = 1, Name = "Test", NullableName = null }
        };
        var schema = new List<ColumnSchema>
        {
            new("Id", "int", null, 10, 0, false, 1),
            new("Name", "nvarchar", 50, null, null, false, 2),
            new("NullableName", "nvarchar", 50, null, null, true, 3)
        };

        // Act
        var errors = _validator.ValidateBatch(data, schema);

        // Assert
        Assert.Empty(errors);
    }

    [Fact]
    public void ValidateBatch_DecimalOverflow_ReturnsError()
    {
        // Arrange
        var data = new List<TestEntity>
        {
            new() { Id = 1, Name = "Test", Amount = 12345678.90m } // Too many integer digits for decimal(8,2)
        };
        var schema = new List<ColumnSchema>
        {
            new("Id", "int", null, 10, 0, false, 1),
            new("Name", "nvarchar", 50, null, null, false, 2),
            new("Amount", "decimal", null, 8, 2, false, 3) // Max 6 integer digits
        };

        // Act
        var errors = _validator.ValidateBatch(data, schema);

        // Assert
        Assert.Single(errors);
        Assert.Equal("Amount", errors[0].ColumnName);
        Assert.Contains("exceeds maximum integer digits", errors[0].Message);
    }

    [Fact]
    public void ValidateBatch_DecimalWithinRange_NoError()
    {
        // Arrange
        var data = new List<TestEntity>
        {
            new() { Id = 1, Name = "Test", Amount = 123456.78m } // Within decimal(10,2) - 8 integer digits
        };
        var schema = new List<ColumnSchema>
        {
            new("Id", "int", null, 10, 0, false, 1),
            new("Name", "nvarchar", 50, null, null, false, 2),
            new("Amount", "decimal", null, 10, 2, false, 3) // Max 8 integer digits
        };

        // Act
        var errors = _validator.ValidateBatch(data, schema);

        // Assert
        Assert.Empty(errors);
    }

    [Fact]
    public void ValidateBatch_MultipleErrors_ReturnsAll()
    {
        // Arrange
        var data = new List<TestEntity>
        {
            new() { Id = 1, Name = "This is too long" },
            new() { Id = 2, Name = "Also too long!" }
        };
        var schema = new List<ColumnSchema>
        {
            new("Id", "int", null, 10, 0, false, 1),
            new("Name", "nvarchar", 5, null, null, false, 2)
        };

        // Act
        var errors = _validator.ValidateBatch(data, schema);

        // Assert
        Assert.Equal(2, errors.Count);
        Assert.Equal(0, errors[0].RowIndex);
        Assert.Equal(1, errors[1].RowIndex);
    }

    [Fact]
    public void ValidateBatch_MaxErrors_StopsAtLimit()
    {
        // Arrange
        var data = Enumerable.Range(0, 10)
            .Select(i => new TestEntity { Id = i, Name = "This is way too long" })
            .ToList();
        var schema = new List<ColumnSchema>
        {
            new("Id", "int", null, 10, 0, false, 1),
            new("Name", "nvarchar", 5, null, null, false, 2)
        };

        // Act
        var errors = _validator.ValidateBatch(data, schema, maxErrors: 3);

        // Assert
        Assert.Equal(3, errors.Count);
    }

    [Fact]
    public void ValidateBatch_UnmatchedColumn_Ignored()
    {
        // Arrange
        var data = new List<TestEntity>
        {
            new() { Id = 1, Name = "Test" }
        };
        var schema = new List<ColumnSchema>
        {
            new("Id", "int", null, 10, 0, false, 1),
            new("Name", "nvarchar", 50, null, null, false, 2),
            new("UnknownColumn", "nvarchar", 50, null, null, false, 3)
        };

        // Act
        var errors = _validator.ValidateBatch(data, schema);

        // Assert
        Assert.Empty(errors);
    }

    [Fact]
    public void ValidateBatch_IdColumn_AllowsNull()
    {
        // Arrange - Id columns are treated as identity/auto-generated
        var data = new List<TestEntity>
        {
            new() { Id = 0, Name = "Test" } // Id = 0 might be treated as "not set"
        };
        var schema = new List<ColumnSchema>
        {
            new("Id", "int", null, 10, 0, false, 1), // Not nullable in schema
            new("Name", "nvarchar", 50, null, null, false, 2)
        };

        // Act
        var errors = _validator.ValidateBatch(data, schema);

        // Assert - No error because Id columns are treated specially
        Assert.Empty(errors);
    }

    #endregion
}