package testing

import (
	"testing"

	E "github.com/ibm/fp-go/eq"
	LA "github.com/ibm/fp-go/internal/applicative/testing"
	LC "github.com/ibm/fp-go/internal/chain/testing"
	"github.com/stretchr/testify/assert"
)

// Apply monad left identity law
//
// M.chain(M.of(a), f) <-> f(a)
func AssertLeftIdentity[HKTA, HKTB, A, B any](t *testing.T,
	eq E.Eq[HKTB],

	fofa func(A) HKTA,
	fofb func(B) HKTB,

	fchain func(HKTA, func(A) HKTB) HKTB,

	ab func(A) B,
) func(a A) bool {
	return func(a A) bool {

		f := func(a A) HKTB {
			return fofb(ab(a))
		}

		left := fchain(fofa(a), f)
		right := f(a)

		return assert.True(t, eq.Equals(left, right), "Monad left identity")
	}
}

// Apply monad right identity law
//
// M.chain(fa, M.of) <-> fa
func AssertRightIdentity[HKTA, A any](t *testing.T,
	eq E.Eq[HKTA],

	fofa func(A) HKTA,

	fchain func(HKTA, func(A) HKTA) HKTA,
) func(fa HKTA) bool {
	return func(fa HKTA) bool {

		left := fchain(fa, fofa)
		right := fa

		return assert.True(t, eq.Equals(left, right), "Monad right identity")
	}
}

// AssertLaws asserts the apply laws `identity`, `composition`, `associative composition`, 'applicative identity', 'homomorphism', 'interchange', `associativity`, `left identity`, `right identity`
func AssertLaws[HKTA, HKTB, HKTC, HKTAA, HKTAB, HKTBC, HKTAC, HKTABB, HKTABAC, A, B, C any](t *testing.T,
	eqa E.Eq[HKTA],
	eqb E.Eq[HKTB],
	eqc E.Eq[HKTC],

	fofa func(A) HKTA,
	fofb func(B) HKTB,
	fofc func(C) HKTC,

	fofaa func(func(A) A) HKTAA,
	fofab func(func(A) B) HKTAB,
	fofbc func(func(B) C) HKTBC,
	fofabb func(func(func(A) B) B) HKTABB,

	faa func(HKTA, func(A) A) HKTA,
	fab func(HKTA, func(A) B) HKTB,
	fac func(HKTA, func(A) C) HKTC,
	fbc func(HKTB, func(B) C) HKTC,

	fmap func(HKTBC, func(func(B) C) func(func(A) B) func(A) C) HKTABAC,

	chainaa func(HKTA, func(A) HKTA) HKTA,
	chainab func(HKTA, func(A) HKTB) HKTB,
	chainac func(HKTA, func(A) HKTC) HKTC,
	chainbc func(HKTB, func(B) HKTC) HKTC,

	fapaa func(HKTAA, HKTA) HKTA,
	fapab func(HKTAB, HKTA) HKTB,
	fapbc func(HKTBC, HKTB) HKTC,
	fapac func(HKTAC, HKTA) HKTC,

	fapabb func(HKTABB, HKTAB) HKTB,
	fapabac func(HKTABAC, HKTAB) HKTAC,

	ab func(A) B,
	bc func(B) C,
) func(a A) bool {
	// applicative laws
	applicative := LA.AssertLaws(t, eqa, eqb, eqc, fofa, fofb, fofaa, fofab, fofbc, fofabb, faa, fab, fac, fbc, fmap, fapaa, fapab, fapbc, fapac, fapabb, fapabac, ab, bc)
	// chain laws
	chain := LC.AssertLaws(t, eqa, eqc, fofa, fofb, fofc, fofab, fofbc, faa, fab, fac, fbc, fmap, chainab, chainac, chainbc, fapab, fapbc, fapac, fapabac, ab, bc)
	// monad laws
	leftIdentity := AssertLeftIdentity(t, eqb, fofa, fofb, chainab, ab)
	rightIdentity := AssertRightIdentity(t, eqa, fofa, chainaa)

	return func(a A) bool {
		fa := fofa(a)
		return applicative(a) && chain(fa) && leftIdentity(a) && rightIdentity(fa)
	}
}