package list

import (
	"regexp"
	"strings"
	"testing"

	"github.com/stretchr/testify/assert"
	"pgregory.net/rapid"
)

func intListGen() *rapid.Generator[IList] {
	return rapid.OneOf(rapid.Custom(func(t *rapid.T) IList {
		myList := Empty()
		t.Repeat(map[string]func(*rapid.T){
			"conj": func(t *rapid.T) {
				myList = myList.Conj(rapid.Int().Draw(t, "el"))
			},
		})
		return myList
	}), rapid.Just(Empty()))
}

// generative tests
func TestConjIncreasesLength(t *testing.T) {
	rapid.Check(t, func(t *rapid.T) {
		myList := intListGen().Draw(t, "myList")
		assert.Equal(t, myList.Len()+1, myList.Conj(42).Len())
	})
}

func TestRestDecreasesLengthForNonEmptyList(t *testing.T) {
	rapid.Check(t, func(t *rapid.T) {
		myList := intListGen().Filter(func(l IList) bool {
			return !l.IsEmpty()
		}).Draw(t, "myList")
		assert.Equal(t, myList.Len()-1, myList.Rest().Len())
	})
}

func TestFirstIsNilWhenEmpty(t *testing.T) {
	rapid.Check(t, func(t *rapid.T) {
		myList := intListGen().Draw(t, "myList")
		assert.Equal(t, myList.IsEmpty(), myList.First() == nil)
	})
}

func TestStringifyIntList(t *testing.T) {
	assert.Equal(t, "(1 2 3)", New(3).Conj(2).Conj(1).String())
	rapid.Check(t, func(t *rapid.T) {
		myList := intListGen().Draw(t, "myList")
		s := myList.String()
		r := regexp.MustCompile(`\(.*\)`)
		assert.Equal(t, true, r.Match([]byte(s)))
		if !myList.IsEmpty() {
			assert.Equal(t, myList.Len(), strings.Count(s, " ")+1)
		} else {
			assert.Equal(t, 0, strings.Count(s, " "))
		}
	})
}