package declaration

import (
	"errors"
	"strings"
	"testing"
)

// Each test names the decision it defends (novox/hq ADR 0034). The decision here is ADR 0043,
// and the property it turns on is that unknown is REFUSED, never skipped.

func valid() string {
	return `{"declaration":1,"resources":[
	  {"id":"etc","type":"directory","path":"/etc/mesh","mode":"0755"},
	  {"id":"conf","type":"file","path":"/etc/mesh/host.conf","content":"a\n","mode":"0640"},
	  {"id":"svc","type":"service","unit":"mesh-host.service","state":"running"}
	]}`
}

func refusalFor(t *testing.T, raw string) *RefusalError {
	t.Helper()
	_, err := Parse([]byte(raw))
	if err == nil {
		t.Fatal("expected a refusal")
	}
	var refusal *RefusalError
	if !errors.As(err, &refusal) {
		t.Fatalf("expected a RefusalError, got %T: %v", err, err)
	}
	return refusal
}

func TestAValidDeclarationParsesInOrder(t *testing.T) {
	d, err := Parse([]byte(valid()))
	if err != nil {
		t.Fatalf("unexpected refusal: %v", err)
	}
	// Order is stated, not derived. The host must not sort.
	got := []string{d.Resources[0].ID, d.Resources[1].ID, d.Resources[2].ID}
	want := []string{"etc", "conf", "svc"}
	for i := range want {
		if got[i] != want[i] {
			t.Fatalf("resources reordered: %v, want %v", got, want)
		}
	}
}

func TestAnUnknownTypeRefusesTheWholeDeclaration(t *testing.T) {
	// The property everything else rests on. A host that skipped what it did not understand
	// would apply most of a declaration and report success — a node that looks configured and
	// is not, which is 04-ISSUES/003 with the declaration on the other side of the wire.
	refusal := refusalFor(t, `{"declaration":1,"resources":[
	  {"id":"ok","type":"directory","path":"/etc/mesh"},
	  {"id":"what","type":"blockchain","path":"/etc/mesh"}
	]}`)

	joined := strings.Join(refusal.Problems, "\n")
	if !strings.Contains(joined, "blockchain") {
		t.Errorf("the unknown type was not named: %v", refusal.Problems)
	}
	// And it must say what IS understood, or the reader goes to the source to find out.
	if !strings.Contains(joined, "directory") || !strings.Contains(joined, "service") {
		t.Errorf("the refusal does not say what this host understands: %v", refusal.Problems)
	}
}

func TestAnUnknownFieldIsRefused(t *testing.T) {
	// A field the host does not know is a thing the control plane believes it asked for.
	refusal := refusalFor(t, `{"declaration":1,"resources":[
	  {"id":"conf","type":"file","path":"/etc/x","content":"a","owner":"root"}
	]}`)
	if !strings.Contains(strings.Join(refusal.Problems, "\n"), "owner") {
		t.Errorf("the unknown field was not named: %v", refusal.Problems)
	}
}

func TestAFieldTheTypeDoesNotUseIsRefusedNotIgnored(t *testing.T) {
	// The same fault in miniature: set and ignored means the control plane believes it asked
	// for something the host will never do.
	refusal := refusalFor(t, `{"declaration":1,"resources":[
	  {"id":"svc","type":"service","unit":"a.service","state":"running","path":"/etc/x"}
	]}`)
	joined := strings.Join(refusal.Problems, "\n")
	if !strings.Contains(joined, "path") || !strings.Contains(joined, "Refused rather than ignored") {
		t.Errorf("a field a service does not use was accepted: %v", refusal.Problems)
	}
}

func TestAnUnknownVersionIsRefusedWhole(t *testing.T) {
	// An older host handed a newer vocabulary must not quietly do half of it.
	refusal := refusalFor(t, `{"declaration":99,"resources":[
	  {"id":"a","type":"directory","path":"/etc/mesh"}
	]}`)
	joined := strings.Join(refusal.Problems, "\n")
	if !strings.Contains(joined, "99") || !strings.Contains(joined, "version 1") {
		t.Errorf("the version mismatch was not stated plainly: %v", refusal.Problems)
	}
	// Nothing else is reported, because everything else assumes a vocabulary this host does
	// not have — a list of complaints derived from the wrong grammar is noise.
	if len(refusal.Problems) != 1 {
		t.Errorf("expected only the version problem, got: %v", refusal.Problems)
	}
}

func TestEveryProblemIsReportedAtOnce(t *testing.T) {
	// A declaration is generated, so a person reading a refusal is debugging the generator.
	// Fixing one problem at a time and re-running to find the next wastes their afternoon.
	refusal := refusalFor(t, `{"declaration":1,"resources":[
	  {"id":"","type":"directory","path":"/a"},
	  {"id":"b","type":"file"},
	  {"id":"c","type":"service","unit":"x.service","state":"dancing"}
	]}`)
	if len(refusal.Problems) < 3 {
		t.Errorf("expected every problem at once, got: %v", refusal.Problems)
	}
}

func TestIdentityIsRequiredAndUnique(t *testing.T) {
	// Identity is what lets the store know this is the same resource it applied last time,
	// which is what makes removal possible at all.
	refusal := refusalFor(t, `{"declaration":1,"resources":[
	  {"id":"same","type":"directory","path":"/a"},
	  {"id":"same","type":"directory","path":"/b"}
	]}`)
	if !strings.Contains(strings.Join(refusal.Problems, "\n"), "already used") {
		t.Errorf("a duplicate identity was accepted: %v", refusal.Problems)
	}
}

func TestModeIsRefusedUnlessItMeansWhatItLooksLike(t *testing.T) {
	// "644" and "0644" differ, and the one that looks right in a manifest is the four-digit
	// form. Accepting both would make a mode mean two things.
	for _, mode := range []string{"644", "0999", "rwxr-xr-x", "07777777"} {
		refusal := refusalFor(t, `{"declaration":1,"resources":[
		  {"id":"f","type":"file","path":"/a","mode":"`+mode+`"}
		]}`)
		if !strings.Contains(strings.Join(refusal.Problems, "\n"), "mode") {
			t.Errorf("mode %q was accepted: %v", mode, refusal.Problems)
		}
	}
	if _, err := Parse([]byte(`{"declaration":1,"resources":[
	  {"id":"f","type":"file","path":"/a","mode":"0644"}
	]}`)); err != nil {
		t.Errorf("a well-formed mode was refused: %v", err)
	}
}

func TestARefusalSaysNothingWasApplied(t *testing.T) {
	// The reader's first question is whether the machine was left half-changed.
	refusal := refusalFor(t, `{"declaration":1,"resources":[{"id":"x","type":"nope"}]}`)
	if !strings.Contains(refusal.Error(), "none of it was applied") {
		t.Errorf("the refusal does not say the machine is untouched: %s", refusal.Error())
	}
}

func TestAnEmptyDeclarationIsAMistake(t *testing.T) {
	refusalFor(t, `{"declaration":1,"resources":[]}`)
}