package lint

import (
	"go/parser"
	"go/token"
	"strings"
	"testing"
)

// The lint, over this repository (novox/hq to-be 45 Phase 2, ADR 0227 rule 4 "how it is checked"): every
// error branch that answers an empty collection says why that is the truth, or the build fails naming it.
func TestNoReaderAnswersEmptyForAnError(t *testing.T) {
	found, err := EmptyOnError("../..")
	if err != nil {
		t.Fatal(err)
	}
	allowed := 0
	for _, f := range found {
		if f.Allowed != "" {
			allowed++
			continue
		}
		t.Errorf("%s answers an empty collection and no error when it could not read: refuse by name "+
			"(return the error), or say at the return why empty is the truth (// %s <why>)", f, Allow)
	}
	t.Logf("%d error branch(es) answer empty, each saying why", allowed)
}

// The lint itself: what it finds, and what it does not.
func TestTheLintFindsEmptyOnError(t *testing.T) {
	const src = `package x

func readContributions() []string {
	raw, err := read()
	if err != nil {
		return nil
	}
	return parse(raw)
}

func consumers() ([]string, error) {
	if err := load(); err != nil {
		return []string{}, nil
	}
	return nil, nil
}

func byName() (map[string]int, error) {
	if err := load(); err != nil {
		return nil, err
	}
	return map[string]int{}, nil
}

func allowed() ([]string, error) {
	if err := load(); err != nil {
		// empty-on-error: a store not yet seeded holds no seats, and the caller keeps its defaults
		return nil, nil
	}
	return nil, nil
}

func notFound() ([]string, error) {
	if errors.Is(err, ErrNoRows) {
		return nil, nil
	}
	return nil, nil
}

func inside() {
	f := func() []int {
		if readErr != nil {
			return nil
		}
		return []int{1}
	}
	_ = f
}
`
	fset := token.NewFileSet()
	file, err := parser.ParseFile(fset, "x.go", src, parser.ParseComments)
	if err != nil {
		t.Fatal(err)
	}
	var failing, allowedFns []string
	for _, f := range inFile(fset, file, "x.go") {
		if f.Allowed != "" {
			allowedFns = append(allowedFns, f.Func)
			continue
		}
		failing = append(failing, f.Func)
	}
	want := "readContributions consumers inside (a function inside it)"
	if strings.Join(failing, " ") != want {
		t.Fatalf("the lint found %q, want %q", failing, want)
	}
	if strings.Join(allowedFns, " ") != "allowed" {
		t.Fatalf("the allowance was not read: %q", allowedFns)
	}
}