namespace FlexArray.Test;

public class FlexArrayStringTests
{
    // Constructor tests
    [Fact]
    public void Construction_NoSize()
    {
        var array = new FlexArrayString();

        array.Should().NotBeNull();
        array.Count.Should().Be(0, "no items added yet");
        array.Capacity.Should().Be(FlexArrayString.DefaultStartSize, "default capacity");
    }
    
    [Theory]
    [InlineData(0)]
    [InlineData(4)]
    [InlineData(20)]
    [InlineData(100_000)]
    public void Construction_WithSize(int size)
    {
        var array = new FlexArrayString(size);

        array.Should().NotBeNull();
        array.Count.Should().Be(0, "no items added yet");
        array.Capacity.Should().Be(size, "initial capacity set to specified size");
    }

    [Fact]
    public void Construction_WithInvalidSize()
    {
        var array = new FlexArrayString(-5);

        array.Should().NotBeNull();
        array.Count.Should().Be(0);
        array.Capacity.Should().Be(0, "negative size provided => set to 0");
    }
    
    // Add tests
    [Fact]
    public void AddItem_Single()
    {
        var array = new FlexArrayString();

        array.Add("Hello");

        array.Count.Should().Be(1, "one item added");
        array.Capacity.Should().Be(FlexArrayString.DefaultStartSize, "capacity unchanged");
    }
    
    [Fact]
    public void AddItem_Multiple_NoGrowth()
    {
        var array = new FlexArrayString();

        array.Add("Hello");
        array.Add("World");
        array.Add("!");

        array.Count.Should().Be(3, "three items added");
        array.Capacity.Should().Be(FlexArrayString.DefaultStartSize, "no growth required yet");
    }

    [Fact]
    public void AddItem_Multiple_Growth()
    {
        var array = new FlexArrayString();

        void AddItems(int count) 
        {
            for (var i = 0; i < count; i++)
            {
                // random string
                array.Add(Guid.NewGuid().ToString());
            }
        }

        AddItems(FlexArrayString.DefaultStartSize);
        array.Capacity.Should().Be(FlexArrayString.DefaultStartSize);

        AddItems(2);
        array.Capacity.Should().BeGreaterThan(FlexArrayString.DefaultStartSize, "capacity exceeded, had to grow"); 
        array.Count.Should().Be(FlexArrayString.DefaultStartSize + 2);
    }
}