open Jest
open Expect
open TestHelpers

let {
    algebraicAdd, 
    algebraicMultiply, 
    algebraicDivide, 
    algebraicSubtract, 
    algebraicLogarithm, 
    algebraicPower
} = module(DistributionOperation.Constructors)

let algebraicAdd = algebraicAdd(~env)
let algebraicMultiply = algebraicMultiply(~env)
let algebraicDivide = algebraicDivide(~env)
let algebraicSubtract = algebraicSubtract(~env)
let algebraicLogarithm = algebraicLogarithm(~env)
let algebraicPower = algebraicPower(~env)


describe("Mean", () => {

    let mean = GenericDist_Types.Constructors.UsingDists.mean

    let runMean: result<DistributionTypes.genericDist, DistributionTypes.error> => float = distR => {
        switch distR->E.R2.fmap(mean)->E.R2.fmap(run)->E.R2.fmap(toFloat) {
            | Ok(Some(x)) => x
            | _ => 9e99  // We trust input in test fixtures so this won't happen 
        }
    }
    
    let impossiblePath: string => assertion = algebraicOp => `${algebraicOp} has`->expect->toEqual("failed")

    let distributions = list{
        normalMake(0.0, 1e0), 
        betaMake(2e0, 4e0), 
        exponentialMake(1.234e0), 
        uniformMake(7e0, 1e1), 
        // cauchyMake(1e0, 1e0), 
        lognormalMake(1e0, 1e0), 
        triangularMake(1e0, 1e1, 5e1), 
        Ok(floatMake(1e1))
    }
    let combinations = E.L.combinations2(distributions)
    let zipDistsDists = E.L.zip(distributions, distributions)
    let digits = -4

    describe("addition", () => {
        let testAdditionMean = (dist1'', dist2'') => {
            let dist1' = E.R.fmap(x => DistributionTypes.Symbolic(x), dist1'')
            let dist2' = E.R.fmap(x => DistributionTypes.Symbolic(x), dist2'')
            let dist1 = E.R.fmap2(s => DistributionTypes.Other(s), dist1')
            let dist2 = E.R.fmap2(s => DistributionTypes.Other(s), dist2')
    
            let received = E.R.liftJoin2(algebraicAdd, dist1, dist2) 
                -> E.R2.fmap(mean) 
                -> E.R2.fmap(run) 
                -> E.R2.fmap(toFloat)
            let expected = runMean(dist1) +. runMean(dist2)
            switch received {
              | Error(err) => impossiblePath("algebraicAdd")
              | Ok(x) => 
                    switch x {
                      | None => impossiblePath("algebraicAdd")
                      | Some(x) => x->expect->toBeSoCloseTo(expected, ~digits=digits)
                    }
            }
        }

        testAll("homogeneous addition", zipDistsDists, dists => {
            let (dist1, dist2) = dists
            testAdditionMean(dist1, dist2)
        })

        testAll("heterogeneoous addition (1)", combinations, dists => {
            let (dist1, dist2) = dists
            testAdditionMean(dist1, dist2)
        })

        testAll("heterogeneoous addition (commuted of 1 (or; 2))", combinations, dists => {
            let (dist1, dist2) = dists
            testAdditionMean(dist2, dist1)
        })
    })

    describe("subtraction", () => {
        let testSubtractionMean = (dist1'', dist2'') => {
            let dist1' = E.R.fmap(x => DistributionTypes.Symbolic(x), dist1'')
            let dist2' = E.R.fmap(x => DistributionTypes.Symbolic(x), dist2'')
            let dist1 = E.R.fmap2(s => DistributionTypes.Other(s), dist1')
            let dist2 = E.R.fmap2(s => DistributionTypes.Other(s), dist2')
    
            let received = E.R.liftJoin2(algebraicSubtract, dist1, dist2) 
                -> E.R2.fmap(mean) 
                -> E.R2.fmap(run) 
                -> E.R2.fmap(toFloat)
            let expected = runMean(dist1) -. runMean(dist2)
            switch received {
              | Error(err) => impossiblePath("algebraicSubtract")
              | Ok(x) => 
                    switch x {
                      | None => impossiblePath("algebraicSubtract")
                      | Some(x) => x->expect->toBeSoCloseTo(expected, ~digits=digits)
                    }
            }
        }

        testAll("homogeneous subtraction", zipDistsDists, dists => {
            let (dist1, dist2) = dists
            testSubtractionMean(dist1, dist2)
        })

        testAll("heterogeneoous subtraction (1)", combinations, dists => {
            let (dist1, dist2) = dists
            testSubtractionMean(dist1, dist2)
        })

        testAll("heterogeneoous subtraction (commuted of 1 (or; 2))", combinations, dists => {
            let (dist1, dist2) = dists
            testSubtractionMean(dist2, dist1)
        })

    })

    describe("multiplication", () => {
        let testMultiplicationMean = (dist1'', dist2'') => {
            let dist1' = E.R.fmap(x => DistributionTypes.Symbolic(x), dist1'')
            let dist2' = E.R.fmap(x => DistributionTypes.Symbolic(x), dist2'')
            let dist1 = E.R.fmap2(s => DistributionTypes.Other(s), dist1')
            let dist2 = E.R.fmap2(s => DistributionTypes.Other(s), dist2')
    
            let received = E.R.liftJoin2(algebraicMultiply, dist1, dist2) 
                -> E.R2.fmap(mean) 
                -> E.R2.fmap(run) 
                -> E.R2.fmap(toFloat)
            let expected = runMean(dist1) *. runMean(dist2)
            switch received {
              | Error(err) => impossiblePath("algebraicMultiply")
              | Ok(x) => 
                    switch x {
                      | None => impossiblePath("algebraicMultiply")
                      | Some(x) => x->expect->toBeSoCloseTo(expected, ~digits=digits)
                    }
            }
        }

        testAll("homogeneous subtraction", zipDistsDists, dists => {
            let (dist1, dist2) = dists
            testMultiplicationMean(dist1, dist2)
        })

        testAll("heterogeneoous subtraction (1)", combinations, dists => {
            let (dist1, dist2) = dists
            testMultiplicationMean(dist1, dist2)
        })

        testAll("heterogeneoous subtraction (commuted of 1 (or; 2))", combinations, dists => {
            let (dist1, dist2) = dists
            testMultiplicationMean(dist2, dist1)
        })

    })
})