// LeetCode 3027 單元測試
// 使用 xUnit 框架

using Xunit;
using System;
using System.Collections.Generic;

public class SolutionTests
{
    private readonly Solution _solution;

    public SolutionTests()
    {
        _solution = new Solution();
    }

    [Fact]
    public void TestCase1_ExampleFromProblem()
    {
        // Arrange
        int[][] points = new int[][] {
            new int[] {6, 2},
            new int[] {4, 4},
            new int[] {2, 6}
        };
        int expected = 2;

        // Act
        var result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }

    [Fact]
    public void TestCase2_TwoPoints()
    {
        // Arrange
        int[][] points = new int[][] {
            new int[] {1, 3},
            new int[] {2, 1}
        };
        int expected = 1;

        // Act
        var result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }

    [Fact]
    public void TestCase3_NoValidPairs()
    {
        // Arrange - 沒有有效點對的情況
        int[][] points = new int[][] {
            new int[] {1, 1},
            new int[] {2, 2},
            new int[] {3, 3}
        };
        int expected = 0;

        // Act
        var result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }

    [Fact]
    public void TestCase4_SameXCoordinate()
    {
        // Arrange - x 座標相同的情況
        int[][] points = new int[][] {
            new int[] {3, 5},
            new int[] {3, 2},
            new int[] {3, 1}
        };
        int expected = 2;

        // Act
        var result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }

    [Fact]
    public void TestCase5_SameYCoordinate()
    {
        // Arrange - y 座標相同的情況
        int[][] points = new int[][] {
            new int[] {1, 4},
            new int[] {3, 4},
            new int[] {5, 4}
        };
        int expected = 2;

        // Act
        var result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }

    [Fact]
    public void TestCase6_PointsInsideRectangle()
    {
        // Arrange - 矩形內有其他點的情況
        int[][] points = new int[][] {
            new int[] {0, 4},    // A
            new int[] {4, 0},    // B  
            new int[] {2, 2}     // C (在 A-B 矩形內)
        };

        int expected = 2;

        // Act
        var result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }

    [Fact]
    public void TestCase7_PointsOnBorder()
    {
        // Arrange - 點在矩形邊界上的情況
        int[][] points = new int[][] {
            new int[] {0, 3},    // A
            new int[] {3, 0},    // B
            new int[] {0, 0}     // C (在矩形邊界上)
        };
        int expected = 2; // (A,C) 和 (C,B) 有效

        // Act
        var result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }

    [Fact]
    public void TestCase8_NegativeCoordinates()
    {
        // Arrange - 負座標情況 (題目一允許 -10^9 到 10^9)
        int[][] points = new int[][] {
            new int[] {-5, 5},
            new int[] {5, -5},
            new int[] {0, 0}
        };
        int expected = 2; // (-5,5) -> (0,0) 和 (0,0) -> (5,-5) 有效

        // Act
        var result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }

    [Fact]
    public void TestCase9_LargeCoordinates()
    {
        // Arrange - 大座標值情況
        int[][] points = new int[][] {
            new int[] {-1000000, 1000000},
            new int[] {1000000, -1000000},
            new int[] {0, 0}
        };
        int expected = 2;

        // Act
        var result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }

    [Fact]
    public void TestEdgeCases_MinimumPoints()
    {
        // Arrange - 最少點數情況 (題目限制 n >= 2)
        int[][] points = new int[][] {
            new int[] {0, 1},
            new int[] {1, 0}
        };
        int expected = 1; // (0,1) 在 (1,0) 的左上方

        // Act
        int result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }

    [Fact]
    public void TestEdgeCases_MaximumCoordinateRange()
    {
        // Arrange - 最大座標範圍測試
        int[][] points = new int[][] {
            new int[] {-1000000000, 1000000000},  // 最小x，最大y
            new int[] {1000000000, -1000000000},  // 最大x，最小y
            new int[] {0, 0}                      // 中心點
        };
        int expected = 2;

        // Act
        int result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }

    [Fact]
    public void TestCase_LargerDataSet()
    {
        // Arrange - 較大的數據集 (接近題目一的限制 n <= 1000)
        var points = new List<int[]>();
        
        // 創建 100 個不同的點 (可以增加到更接近 1000，但為了測試速度這裡用 100)
        for (int i = 0; i < 10; i++)
        {
            for (int j = 0; j < 10; j++)
            {
                points.Add(new int[] { i * 100 - 500, j * 100 - 500 });
            }
        }
        
        int[][] pointsArray = points.ToArray();
        
        // Act
        int result = _solution.NumberOfPairs(pointsArray);
        
        // Assert
        Assert.True(result >= 0); // 結果應該是非負數
        Assert.True(result <= 100 * 99); // 最多不會超過所有可能的點對
    }

    [Fact]
    public void TestCase_StressTest_MediumSize()
    {
        // Arrange - 中等規模壓力測試 (200個點)
        var points = new List<int[]>();
        var usedPoints = new HashSet<string>();
        var random = new Random(42); // 固定種子確保可重現

        while (points.Count < 200)
        {
            int x = random.Next(-10000, 10001); // 較大範圍
            int y = random.Next(-10000, 10001);
            string pointKey = $"{x},{y}";

            if (!usedPoints.Contains(pointKey))
            {
                usedPoints.Add(pointKey);
                points.Add(new int[] { x, y });
            }
        }

        int[][] pointsArray = points.ToArray();

        // Act
        var startTime = DateTime.Now;
        int result = _solution.NumberOfPairs(pointsArray);
        var endTime = DateTime.Now;
        var elapsed = endTime - startTime;

        // Assert
        Assert.True(result >= 0);
        Assert.True(result <= 200 * 199);
        Assert.True(elapsed.TotalMilliseconds < 5000); // 應該在5秒內完成
    }

    [Fact]
    public void TestCase_AllPointsOnSameLine_Vertical()
    {
        // Arrange - 所有點在同一條垂直線上
        int[][] points = new int[][] {
            new int[] {0, 10},
            new int[] {0, 5},
            new int[] {0, 0},
            new int[] {0, -5},
            new int[] {0, -10}
        };
        int expected = 4; // 每個點都可以與y座標更小的點配對

        // Act
        int result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }

    [Fact]
    public void TestCase_AllPointsOnSameLine_Horizontal()
    {
        // Arrange - 所有點在同一條水平線上
        int[][] points = new int[][] {
            new int[] {-10, 0},
            new int[] {-5, 0},
            new int[] {0, 0},
            new int[] {5, 0},
            new int[] {10, 0}
        };
        int expected = 4; // 每個點都可以與x座標更大的點配對

        // Act
        int result = _solution.NumberOfPairs(points);

        // Assert
        Assert.Equal(expected, result);
    }
}