module ParasitemiaCore.Histogram

open System
open System.Drawing

open Emgu.CV
open Emgu.CV.Structure

type Histogram =
    {
        data : int[]
        total : int // Number of elements.
        sum : int // Sum of all intensity.
        min : float32
        max : float32
    }

let histogramImg (img : Image<Gray, float32>) (nbSamples : int) : Histogram =
    let imgData = img.Data

    let min, max =
        let min = ref [| 0.0 |]
        let minLocation = ref <| [| Point () |]
        let max = ref [| 0.0 |]
        let maxLocation = ref <| [| Point () |]
        img.MinMax (min, max, minLocation, maxLocation)
        float32 (!min).[0], float32 (!max).[0]

    let inline bin (x : float32) : int =
        let p = int ((x - min) / (max - min) * float32 nbSamples)
        if p >= nbSamples then nbSamples - 1 else p

    let data = Array.zeroCreate nbSamples

    for i = 0 to img.Height - 1 do
        for j = 0 to img.Width - 1 do
            let p = bin imgData.[i, j, 0]
            data.[p] <- data.[p] + 1

    { data = data; total = img.Height * img.Width; sum = Array.sum data; min = min; max = max }

let histogramMat (mat : Matrix<float32>) (nbSamples : int) : Histogram =
    let matData = mat.Data

    let min, max =
        let min = ref 0.0
        let minLocation = ref <| Point ()
        let max = ref 0.0
        let maxLocation = ref <| Point ()
        mat.MinMax (min, max, minLocation, maxLocation)
        float32 !min, float32 !max

    let inline bin (x : float32) : int =
        let p = int ((x - min) / (max - min) * float32 nbSamples)
        if p >= nbSamples then nbSamples - 1 else p

    let data = Array.zeroCreate nbSamples

    for i = 0 to mat.Height - 1 do
        for j = 0 to mat.Width - 1 do
            let p = bin matData.[i, j]
            data.[p] <- data.[p] + 1

    { data = data; total = mat.Height * mat.Width; sum = Array.sum data; min = min; max = max }

let histogram (values : float32 seq) (nbSamples : int) : Histogram =
    let mutable min = Single.MaxValue
    let mutable max = Single.MinValue
    let mutable n = 0

    for v in values do
        n <- n + 1
        if v < min then min <- v
        if v > max then max <- v

    let inline bin (x : float32) : int =
        let p = int ((x - min) / (max - min) * float32 nbSamples)
        if p >= nbSamples then nbSamples - 1 else p

    let data = Array.zeroCreate nbSamples

    for v in values do
        let p = bin v
        data.[p] <- data.[p] + 1

    { data = data; total = n; sum = Array.sum data; min = min; max = max }