package hub

import (
	"encoding/json"
	"os"
	"reflect"
	"sort"
	"testing"
)

// The host-report shape is a contract DUPLICATED across two repos (no shared types
// module yet). testdata/host-report.golden.json MUST be kept byte-identical with
// felhom-hub's hub/internal/api/testdata/host-report.golden.json. This test fails
// if a json tag on HostReport/HostMetrics/Guest is renamed/added/removed relative
// to the golden, catching silent drift before slices 5/6 populate the empty
// collections. (Promote to a shared types module when those land.)
func TestHostReport_ContractMatchesGolden(t *testing.T) {
	raw, err := os.ReadFile("testdata/host-report.golden.json")
	if err != nil {
		t.Fatal(err)
	}
	var golden map[string]any
	if err := json.Unmarshal(raw, &golden); err != nil {
		t.Fatalf("golden is not valid JSON: %v", err)
	}

	// A constructed report mirroring the golden's populated shape (guests[0] has spec).
	report := &HostReport{
		HostID: "demo-host-01", ReportedAt: "2026-06-08T12:00:00Z", AgentVersion: "0.3.1",
		Host: HostMetrics{Node: "demo-felhom", LoadAvg: []string{"0.10"}},
		Guests: []Guest{
			{VMID: 100, Name: "a", Status: "running", ControllerVersion: "", Spec: &GuestSpec{Cores: 2}},
			{VMID: 101, Name: "b", Status: "stopped", ControllerVersion: ""},
		},
		StorageTargets: []StorageTarget{}, Backups: []Backup{}, RestoreTests: []RestoreTest{},
		PBSSnapshots: []PBSSnapshot{}, AuditTail: []AuditEntry{},
		Cloudflared: Cloudflared{Status: "active"},
	}
	b, _ := json.Marshal(report)
	var got map[string]any
	json.Unmarshal(b, &got)

	assertSameKeys(t, "<top>", golden, got)
	assertSameKeys(t, "host", golden["host"], got["host"])
	assertSameKeys(t, "guests[0]",
		firstElem(golden["guests"]), firstElem(got["guests"]))
}

func firstElem(v any) any {
	arr, ok := v.([]any)
	if !ok || len(arr) == 0 {
		return map[string]any{}
	}
	return arr[0]
}

func assertSameKeys(t *testing.T, where string, a, b any) {
	t.Helper()
	ka, kb := keysOf(a), keysOf(b)
	if !reflect.DeepEqual(ka, kb) {
		t.Errorf("contract drift at %s:\n golden keys = %v\n struct keys = %v", where, ka, kb)
	}
}

func keysOf(v any) []string {
	m, ok := v.(map[string]any)
	if !ok {
		return nil
	}
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	return keys
}