package bootstrap

import (
	"archive/tar"
	"bytes"
	"compress/gzip"
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

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

// novox/hq issue 223: what genesis raises is what the controller's process takes over. The temporary
// controller composes the genesis container, and the host records it as `<module>.<its id>`; the
// first declaration the mesh composes from the controller's real manifest names that same id under
// the process's `replaces` (the composer prefixes both alike — mesh-controller's
// TestTheControllerIsAProcessAndNoContainer). So the first apply hands over: the process is started,
// seen up, and only then is the genesis container removed — one controller before, one after, never
// none and never two left.
func TestTheFirstApplyHandsTheGenesisContainerOverToTheProcess(t *testing.T) {
	restore := apply.ForTests(t.TempDir(), t.TempDir())
	defer restore()

	form, err := processFormOf([]byte(processFormManifest))
	if err != nil {
		t.Fatal(err)
	}
	genesis, err := genesisForm([]byte(processFormManifest), form, builtImage)
	if err != nil {
		t.Fatal(err)
	}
	// What the host records for the genesis container, as the composer names it.
	recorded := ""
	var m struct {
		Resources []map[string]any `json:"resources"`
	}
	if err := json.Unmarshal(genesis, &m); err != nil {
		t.Fatal(err)
	}
	for _, r := range m.Resources {
		if r["type"] == "container" {
			recorded = ControlPlaneModule + "." + r["id"].(string)
		}
	}
	known := store.State{Resources: []store.Applied{{Origin: store.OriginDeclared, ID: recorded,
		Type: "container", Target: ControlPlaneModule}}}

	// The controller's first composed declaration: its process, replacing what the manifest names.
	body, digest := aBundle(t)
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) { _, _ = w.Write(body) }))
	defer server.Close()
	replaces, _ := json.Marshal([]string{ControlPlaneModule + "." + form.Replaces})
	d, err := declaration.Parse([]byte(`{"declaration":1,"resources":[{"id":"` + ControlPlaneModule + "." + form.Process +
		`","type":"process","name":"mesh-controller","source":"` + server.URL + `/c.tgz","digest":"` + digest +
		`","run":["./mesh-controller","serve"],"replaces":` + string(replaces) + `}]}`))
	if err != nil {
		t.Fatal(err)
	}

	var commands []string
	started, container := false, true
	run := func(_ context.Context, name string, args ...string) (string, error) {
		line := name + " " + strings.Join(args, " ")
		commands = append(commands, line)
		switch {
		case strings.HasPrefix(line, "systemctl restart mesh-controller.service"):
			started = true
		case strings.HasPrefix(line, "systemctl show mesh-controller.service") && started:
			return "ActiveState=active\nSubState=running\nMainPID=7\nNRestarts=0\n", nil
		case strings.HasPrefix(line, "docker rm -f mesh-controller"):
			if !started {
				t.Error("the genesis container was removed before the process was started")
			}
			container = false
		case strings.HasPrefix(line, "docker container inspect") && !container:
			return "", errors.New("no such container")
		}
		return "", nil
	}
	sys, err := system.For("arch")
	if err != nil {
		t.Fatal(err)
	}
	_, after, err := apply.Apply(context.Background(), sys, d, known, store.OriginDeclared, run, nil, nil)
	if err != nil {
		t.Fatalf("the first apply did not hand over: %v\n%s", err, strings.Join(commands, "\n"))
	}
	if container {
		t.Fatalf("the genesis container is still running beside the process — two controllers:\n%s",
			strings.Join(commands, "\n"))
	}
	if _, still := after.Find(recorded); still {
		t.Error("the host still records the genesis container")
	}
}

func aBundle(t *testing.T) ([]byte, string) {
	t.Helper()
	var raw bytes.Buffer
	zipped := gzip.NewWriter(&raw)
	w := tar.NewWriter(zipped)
	content := "#!/bin/sh\n"
	if err := w.WriteHeader(&tar.Header{Name: "mesh-controller", Mode: 0o755, Size: int64(len(content)), Typeflag: tar.TypeReg}); err != nil {
		t.Fatal(err)
	}
	_, _ = w.Write([]byte(content))
	_ = w.Close()
	_ = zipped.Close()
	sum := sha256.Sum256(raw.Bytes())
	return raw.Bytes(), "sha256:" + hex.EncodeToString(sum[:])
}