package apply

import (
	"context"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"github.com/novox/mesh-host/internal/store"
)

// A take is a comparison (novox/hq ADR 0163): while a module's container is held, the host reports
// the found image and its age beside the declared one, the networks and who else is on them, the
// mounts and the ports — and says when the declared image is the older.
func TestAHeldContainerCarriesTheFactsATakeCompares(t *testing.T) {
	dir, page, m := predecessor(t)
	m.containers["hello-web"].image = "web:1.27"
	m.containers["hello-web"].imageID = "sha256:found"
	m.containers["hello-web"].networks = []string{"predecessor_default"}
	m.containers["hello-web"].mounts = []string{"/srv/web:/data"}
	m.containers["hello-web"].ports = []string{"80/tcp>0.0.0.0:8080"}
	m.images = map[string]string{"sha256:found": "2026-09-17T10:00:00Z", pinned: "2026-08-20T10:00:00Z"}
	m.members = map[string][]string{"predecessor_default": {"hello-web", "office", "db"}}

	_, state := applyAdopted(t, adopted(t, untakenWeb, webResources(page)), store.State{}, m, dir)
	h, ok := state.HeldAt("hello-web.server")
	if !ok || h.Facts == nil {
		t.Fatalf("a held container carries no facts: %+v", h)
	}
	f := h.Facts
	if f.Image != "web:1.27" || f.ImageCreated != "2026-09-17T10:00:00Z" {
		t.Errorf("the found image and its age: %+v", f)
	}
	if f.DeclaredImage != pinned || f.DeclaredImageCreated != "2026-08-20T10:00:00Z" || !f.Downgrade {
		t.Errorf("the declared image, its age, and that it is a downgrade: %+v", f)
	}
	if got := f.Networks["predecessor_default"]; len(got) != 2 || got[0] != "db" || got[1] != "office" {
		t.Errorf("the neighbours on the found network, without the container itself: %v", f.Networks)
	}
	if len(f.Mounts) != 1 || f.Mounts[0] != "/srv/web:/data" || len(f.Ports) != 1 || f.Ports[0] != "80/tcp>0.0.0.0:8080" {
		t.Errorf("mounts and ports as found: %+v", f)
	}
	// And the held file carries how the declared content differs from what was found.
	p, ok := state.HeldAt("hello-web.page")
	if !ok || p.Facts == nil || !p.Facts.Differs {
		t.Fatalf("a held file that differs from the declared content does not say so: %+v", p)
	}
	joined := strings.Join(p.Facts.Difference, "\n")
	if !strings.Contains(joined, "- the predecessor's page") || !strings.Contains(joined, "+ the mesh's page") {
		t.Errorf("the difference does not show what is lost and what is new: %q", joined)
	}
	_ = os.Remove(filepath.Join(dir, "unused"))
}

// A declared image not yet on the machine leaves its age unknown and the comparison undecided.
func TestAnImageNotYetPulledLeavesTheDowngradeUndecided(t *testing.T) {
	dir, page, m := predecessor(t)
	m.containers["hello-web"].image = "web:1.27"
	m.containers["hello-web"].imageID = "sha256:found"
	m.images = map[string]string{"sha256:found": "2026-09-17T10:00:00Z"}
	_, state := applyAdopted(t, adopted(t, untakenWeb, webResources(page)), store.State{}, m, dir)
	h, _ := state.HeldAt("hello-web.server")
	if h.Facts == nil || h.Facts.DeclaredImageCreated != "" || h.Facts.Downgrade {
		t.Fatalf("an unknown declared age decided a downgrade: %+v", h.Facts)
	}
}

func TestTheDifferenceIsWhatIsLostAndWhatIsNew(t *testing.T) {
	differs, lines := differenceOf("a\nprivate scope: local\nb\n", "a\nb\nupstream: public\n")
	if !differs || len(lines) != 2 || lines[0] != "- private scope: local" || lines[1] != "+ upstream: public" {
		t.Fatalf("got %v %v", differs, lines)
	}
	if differs, lines := differenceOf("same\n", "same\n"); differs || lines != nil {
		t.Fatalf("identical content differs: %v %v", differs, lines)
	}
}

// What runs on the machine that the mesh neither wrote nor holds is reported (ADR 0163).
func TestStraysAreWhatRunsHereThatNobodyAsked(t *testing.T) {
	m := &machine{containers: map[string]*fakeContainer{
		"hello-web":  {id: "ours", running: true, image: "web:1"},
		"gitea-old":  {id: "left-behind", running: true, image: "gitea:1.22"},
		"held-thing": {id: "found", running: true, image: "x:1"},
	}}
	known := store.State{
		Resources: []store.Applied{{ID: "hello-web.server", Type: "container", Target: "hello-web"}},
		Held:      []store.Held{{ID: "other.server", Kind: "container", Target: "held-thing"}},
	}
	strays, err := Strays(context.Background(), m.run, known)
	if err != nil {
		t.Fatal(err)
	}
	if len(strays) != 1 || strays[0].Name != "gitea-old" || !strings.Contains(strays[0].Detail, "gitea:1.22") {
		t.Fatalf("strays: %+v", strays)
	}
}