package host

import (
	"context"
	"os"
	"strings"
	"testing"

	"github.com/carlosframework/platform/internal/hostguard"
	"github.com/carlosframework/platform/internal/rootstate"
)

func TestPlan14UnitPredecessorHandover(t *testing.T) {
	for _, attack := range []string{"none", "not retired", "same owner", "shape", "replacement", "lost materialization"} {
		t.Run(attack, func(t *testing.T) {
			b, in, shape := plan14UnitBindingFixture(t, "console.service", "", "")
			shape.Program = strings.Repeat("a", 64)
			b.canonical = func(context.Context, string) (claimUnitShape, error) { return shape, nil }
			b.installation = func(context.Context, string) (hostguard.RootInstallation, error) { return in, nil }
			files := &plan14UnitFiles{}
			state := &plan14UnitBindingFault{Store: &rollbackMemory{files: map[string][]byte{}}}
			m := claimUnitMaterializer{idle: func(string) error { return nil }, state: state, read: files.read, create: files.create, replace: files.replace}
			b.handover = m.handover
			old, err := b.establish(t.Context(), in.Host)
			if err != nil {
				t.Fatal(err)
			}
			if err = m.install(t.Context(), old); err != nil {
				t.Fatal(err)
			}
			if attack != "not retired" {
				if err = b.retire(t.Context(), old, func(claimUnitBinding) error { return m.retire(t.Context(), old, func() error { return nil }) }); err != nil {
					t.Fatal(err)
				}
			}
			if attack != "same owner" {
				in.Stamp++
			}
			if attack == "shape" {
				shape.Addr = "127.0.0.1:9999"
			}
			if attack == "replacement" {
				files.id.Inode++
			}
			original := m.replace
			if attack == "lost materialization" {
				m.replace = func(unit string, id rootstate.FileIdentity, body []byte) error {
					if err := original(unit, id, body); err != nil {
						return err
					}
					return os.ErrInvalid
				}
				b.handover = m.handover
			}
			next, err := b.establish(t.Context(), in.Host)
			if attack != "none" && attack != "lost materialization" {
				if err == nil {
					t.Fatal("unsafe handover accepted", next)
				}
				return
			}
			if attack == "lost materialization" {
				if err == nil {
					t.Fatal("lost replacement reported success")
				}
				m.replace = original
				b.handover = m.handover
				next, err = b.establish(t.Context(), in.Host)
			}
			if err != nil {
				t.Fatal(err)
			}
			if next.Owner.Stamp != in.Stamp || next.Retired || next.Retiring {
				t.Fatal(next)
			}
			if err = m.verify(next); err != nil {
				t.Fatal(err)
			}
			if err = b.retire(t.Context(), old, func(claimUnitBinding) error { t.Fatal("predecessor reached successor"); return nil }); err == nil {
				t.Fatal("stale retirement accepted")
			}
			if _, err = b.establish(t.Context(), in.Host); err != nil {
				t.Fatal("replay", err)
			}
		})
	}
}