package kvm

import (
	"bytes"
	"io"
	"maps"
	"reflect"
	"strings"
	"testing"

	"github.com/kdomanski/iso9660"
	"sigs.k8s.io/yaml"
)

func readSeed(t *testing.T, iso []byte) (label string, files map[string]string) {
	t.Helper()
	img, err := iso9660.OpenImage(bytes.NewReader(iso))
	if err != nil {
		t.Fatalf("OpenImage() error = %v", err)
	}
	label, err = img.Label()
	if err != nil {
		t.Fatalf("Label() error = %v", err)
	}
	root, err := img.RootDir()
	if err != nil {
		t.Fatalf("RootDir() error = %v", err)
	}
	children, err := root.GetChildren()
	if err != nil {
		t.Fatalf("GetChildren() error = %v", err)
	}
	files = make(map[string]string, len(children))
	for _, c := range children {
		body, err := io.ReadAll(c.Reader())
		if err != nil {
			t.Fatalf("reading %s: %v", c.Name(), err)
		}
		files[c.Name()] = string(body)
	}
	return label, files
}

func TestBuildSeedISO_contents(t *testing.T) {
	t.Parallel()
	userData := "#cloud-config\npackages: [squid]\n"
	iso, err := buildSeedISO("proxy-abc123def456ghij", userData, guestAgentVendorData)
	if err != nil {
		t.Fatalf("buildSeedISO() error = %v", err)
	}
	label, files := readSeed(t, iso)
	if !strings.EqualFold(label, seedLabel) {
		t.Errorf("label = %q, want %q", label, seedLabel)
	}
	if len(files) != 3 {
		t.Errorf("files = %v, want exactly user-data, meta-data, vendor-data", files)
	}
	if files["user-data"] != userData {
		t.Errorf("user-data = %q, want verbatim cloud-init", files["user-data"])
	}
	if files["vendor-data"] != guestAgentVendorData {
		t.Errorf("vendor-data = %q", files["vendor-data"])
	}
	if got, want := files["meta-data"], "instance-id: proxy-abc123def456ghij\nlocal-hostname: proxy-abc123def456ghij\n"; got != want {
		t.Errorf("meta-data = %q, want %q", got, want)
	}
}

// The writer stamps the build time into the volume descriptor, so two
// builds are not byte-identical; what must not change between them is
// what cloud-init reads: the label and the three files.
func TestBuildSeedISO_deterministicContent(t *testing.T) {
	t.Parallel()
	a, err := buildSeedISO("proxy-x", "#cloud-config\n", "")
	if err != nil {
		t.Fatalf("first buildSeedISO() error = %v", err)
	}
	b, err := buildSeedISO("proxy-x", "#cloud-config\n", "")
	if err != nil {
		t.Fatalf("second buildSeedISO() error = %v", err)
	}
	labelA, filesA := readSeed(t, a)
	labelB, filesB := readSeed(t, b)
	if labelA != labelB || !maps.Equal(filesA, filesB) {
		t.Errorf("two builds for the same inputs differ: %q %v vs %q %v", labelA, filesA, labelB, filesB)
	}
	if len(a) != len(b) {
		t.Errorf("sizes differ: %d vs %d; the seed volume is created with the ISO's exact size", len(a), len(b))
	}
}

func TestBuildSeedISO_emptyUserData(t *testing.T) {
	t.Parallel()
	iso, err := buildSeedISO("proxy-x", "", guestAgentVendorData)
	if err != nil {
		t.Fatalf("buildSeedISO() error = %v", err)
	}
	_, files := readSeed(t, iso)
	if body, ok := files["user-data"]; !ok || body != "" {
		t.Errorf("user-data = %q (present=%v), want an empty file to still exist", body, ok)
	}
}

// parseCloudConfig is what cloud-init sees: the document under the header.
func parseCloudConfig(t *testing.T, doc string) map[string]any {
	t.Helper()
	if first, _, _ := strings.Cut(doc, "\n"); first != cloudConfigHeader {
		t.Fatalf("first line = %q, want %q", first, cloudConfigHeader)
	}
	var cfg map[string]any
	if err := yaml.Unmarshal([]byte(doc), &cfg); err != nil {
		t.Fatalf("merged user-data is not YAML: %v\n%s", err, doc)
	}
	return cfg
}

func TestWithGuestAgent_mergesIntoCloudConfig(t *testing.T) {
	t.Parallel()
	agentCmd := []any{"systemctl", "enable", "--now", "qemu-guest-agent"}
	tests := []struct {
		name         string
		userData     string
		wantPackages []any
		wantRuncmd   []any
	}{
		{
			name:         "empty document",
			userData:     "#cloud-config\n",
			wantPackages: []any{"qemu-guest-agent"},
			wantRuncmd:   []any{agentCmd},
		},
		{
			name:         "no user-data at all",
			userData:     "",
			wantPackages: []any{"qemu-guest-agent"},
			wantRuncmd:   []any{agentCmd},
		},
		{
			// The case that motivated this: cloud-init's default merger keeps
			// the user-data's lists and drops vendor-data's, so the agent must
			// be appended to the user's own packages and runcmd.
			name: "user packages and runcmd are kept and extended",
			userData: "#cloud-config\npackages:\n  - squid\nruncmd:\n  - systemctl restart squid\n" +
				"write_files:\n  - path: /etc/squid/conf.d/x.conf\n    content: |\n      http_port 3128\n      via off\n",
			wantPackages: []any{"squid", "qemu-guest-agent"},
			wantRuncmd:   []any{"systemctl restart squid", agentCmd},
		},
		{
			name:         "agent already present is not duplicated",
			userData:     "#cloud-config\npackages: [qemu-guest-agent]\nruncmd:\n  - [systemctl, enable, --now, qemu-guest-agent]\n",
			wantPackages: []any{"qemu-guest-agent"},
			wantRuncmd:   []any{agentCmd},
		},
		{
			name:         "header with trailing whitespace",
			userData:     "#cloud-config   \r\npackages: [curl]\n",
			wantPackages: []any{"curl", "qemu-guest-agent"},
			wantRuncmd:   []any{agentCmd},
		},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()
			user, vendor, err := withGuestAgent(tc.userData, "")
			if err != nil {
				t.Fatalf("withGuestAgent() error = %v", err)
			}
			if vendor != "" {
				t.Errorf("vendor-data = %q, want none when the agent is merged into the user-data", vendor)
			}
			cfg := parseCloudConfig(t, user)
			if !reflect.DeepEqual(cfg["packages"], tc.wantPackages) {
				t.Errorf("packages = %#v, want %#v", cfg["packages"], tc.wantPackages)
			}
			if !reflect.DeepEqual(cfg["runcmd"], tc.wantRuncmd) {
				t.Errorf("runcmd = %#v, want %#v", cfg["runcmd"], tc.wantRuncmd)
			}
		})
	}
}

func TestWithGuestAgent_keepsOtherKeysAndVendorData(t *testing.T) {
	t.Parallel()
	userData := "#cloud-config\nhostname: px\nwrite_files:\n  - path: /etc/x\n    content: |\n      line one\n      line two\n    permissions: '0644'\nbootcmd: [echo hi]\n"
	user, vendor, err := withGuestAgent(userData, "#cloud-config\nntp: {enabled: true}\n")
	if err != nil {
		t.Fatalf("withGuestAgent() error = %v", err)
	}
	if vendor != "#cloud-config\nntp: {enabled: true}\n" {
		t.Errorf("vendor-data = %q, want the configured one verbatim", vendor)
	}
	got := parseCloudConfig(t, user)
	delete(got, "packages")
	delete(got, "runcmd")
	want := parseCloudConfig(t, userData)
	if !reflect.DeepEqual(got, want) {
		t.Errorf("merged user-data changed the user's keys:\n got %#v\nwant %#v", got, want)
	}
}

func TestWithGuestAgent_nonCloudConfigFallsBackToVendorData(t *testing.T) {
	t.Parallel()
	tests := []struct {
		name       string
		userData   string
		vendorData string
		wantVendor string
	}{
		{"shell script, no vendor-data", "#!/bin/sh\napt-get install -y squid\n", "", guestAgentVendorData},
		{"include, no vendor-data", "#include\nhttps://example/x\n", "", guestAgentVendorData},
		{"shell script, own vendor-data wins", "#!/bin/sh\n", "#cloud-config\nntp: {}\n", "#cloud-config\nntp: {}\n"},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()
			user, vendor, err := withGuestAgent(tc.userData, tc.vendorData)
			if err != nil {
				t.Fatalf("withGuestAgent() error = %v", err)
			}
			if user != tc.userData {
				t.Errorf("user-data = %q, want it untouched", user)
			}
			if vendor != tc.wantVendor {
				t.Errorf("vendor-data = %q, want %q", vendor, tc.wantVendor)
			}
		})
	}
}

func TestWithGuestAgent_rejectsBrokenCloudConfig(t *testing.T) {
	t.Parallel()
	tests := []struct {
		name     string
		userData string
	}{
		{"not yaml", "#cloud-config\npackages: [squid\n"},
		{"not a mapping", "#cloud-config\n- squid\n"},
		{"packages is not a list", "#cloud-config\npackages: squid\n"},
		{"runcmd is not a list", "#cloud-config\nruncmd:\n  a: b\n"},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()
			if _, _, err := withGuestAgent(tc.userData, ""); err == nil {
				t.Errorf("withGuestAgent() = nil error, want one for %q", tc.userData)
			}
		})
	}
}