namespace ParasitemiaCore.Tests

open Xunit
open Xunit.Abstractions

open ParasitemiaCore.KdTree

type Point (x : float32, y : float32) =
    interface I2DCoords with
        member this.X = x
        member this.Y = y

    override this.ToString () =
        sprintf "(%.1f, %.1f)" x y

type KdTreeTests (output : ITestOutputHelper) =

    // TODO: test with identical X or Y coords
    [<Fact>]
    member this.``Test`` () =
        let pts =
            [
                Point (1.0f, 1.0f)
                Point (2.0f, 2.0f)
                Point (1.5f, 3.6f)
                Point (3.0f, 3.2f)
                Point (4.0f, 4.0f)
                Point (3.5f, 1.5f)
                Point (2.5f, 0.5f)
            ]

        let tree = Tree.BuildTree pts
        output.WriteLine (sprintf "Tree: %A" tree)

        let s1 = tree.Search { minX = 0.0f; maxX = 5.0f; minY = 0.0f; maxY = 5.0f } // All points.
        output.WriteLine (sprintf "s1: %A" s1)

        let s2 = tree.Search { minX = 2.8f; maxX = 4.5f; minY = 3.0f; maxY = 4.5f }
        output.WriteLine (sprintf "s2: %A" s2)

        let s3 = tree.Search { minX = 2.0f; maxX = 2.0f; minY = 2.0f; maxY = 2.0f }
        output.WriteLine (sprintf "s3: %A" s3)

    [<Fact>]
    member this.``Test 2`` () =
        let pts =
            [
                Point (1.0f, 1.0f)
                Point (1.0f, 2.0f)
                Point (1.0f, 3.0f)
            ]

        let tree = Tree.BuildTree pts
        output.WriteLine (sprintf "Tree: %A" tree)

        let s1 = tree.Search { minX = 1.0f; maxX = 1.0f; minY = 1.0f; maxY = 1.0f }
        output.WriteLine (sprintf "s1: %A" s1)

        let s2 = tree.Search { minX = 1.0f; maxX = 1.0f; minY = 2.0f; maxY = 2.0f }
        output.WriteLine (sprintf "s2: %A" s2)

        // This case result is wrong: FIXME
        let s3 = tree.Search { minX = 1.0f; maxX = 1.0f; minY = 3.0f; maxY = 3.0f }
        output.WriteLine (sprintf "s3: %A" s3)

        let s4 = tree.Search { minX = 0.0f; maxX = 2.0f; minY = 0.0f; maxY = 4.0f }
        output.WriteLine (sprintf "s4: %A" s4)

    [<Fact>]
    member this.``Benchmark`` () =
        let min = -1_000.
        let max = +1_000.
        let windowSize = 10.
        let nbPoints = 500_000
        let n = 1_000

        let rng = System.Random 42
        let nextNumber (min : float) (max : float) =
            (rng.NextDouble () * (max + abs min)) + min |> float32

        let points =
            [
                for i = 1 to nbPoints do
                    let x = nextNumber min max
                    let y = nextNumber min max
                    Point (x, y)
            ]

        let sw = System.Diagnostics.Stopwatch ()
        sw.Start ()

        let tree = Tree.BuildTree points

        sw.Stop ()
        output.WriteLine (sprintf "Time to build = %A ms" sw.ElapsedMilliseconds)

        sw.Restart ()

        let mutable nbFound = 0
        for i = 1 to n do
            let minX = nextNumber min (max - windowSize)
            let minY = nextNumber min (max - windowSize)
            nbFound <- nbFound + (tree.Search { minX = minX; maxX = minX + float32 windowSize; minY = minY; maxY = minY + float32 windowSize } |> List.length)

        sw.Stop ()
        output.WriteLine (sprintf "nb found: %i. Time to search = %A ms" nbFound sw.ElapsedMilliseconds)