package bootstrap

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"strings"
	"time"

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

// Phase three — nothing is special after installation (novox/hq issue 051).
//
// Genesis raises a store and a broker before any module system exists, because the control plane
// cannot ask provisioning for the store it keeps its own records in or the broker it is reached over
// (novox/hq ADR 0006). That leaves two servers behind: the foundation's, and a second one the
// `postgres` and bus modules used to raise for other modules to use. This turns the foundation's
// own servers into those modules, so a mesh runs ONE postgres and ONE bus — the control plane's
// contexts and the database of each module that asks for one, in the same server (WBS 3.1/3.2).
//
// **Adopted in place, not replaced.** The control plane is stateless and is swapped for a fresh
// container (control.go); the store and broker hold the mesh's memory and its bus, so they are kept.
// The module declares a container with the same name, image and spec the foundation raised, and the
// applier — which keys on the container name and compares a spec digest (mesh-host internal/apply) —
// finds it already running and leaves it be. The image is pinned to the one the foundation is
// running, read from the bundle this installer produced, so the two specs are the same digest and
// nothing is recreated. A recreate happens only on a real upgrade, which is where a stated window
// belongs (WBS 3.3).

// StoreID and BrokerID are what the foundation bundle calls the two servers it raises; the modules
// that adopt them are found by these ids in the bundle this installer produced, the same way the
// control plane's own container is (ControlPlaneID).
const (
	StoreID  = "store"
	BrokerID = "broker"
)

// InstallStore makes the foundation's store the `postgres` module, adopted in place.
//
// The order is InstallFromCatalogue's, with two additions the store needs and an ordinary provider
// does not: the server image is pinned to the one the foundation is already running (so the module's
// container is the same spec and is adopted, not a second one raised), and the superuser password —
// the foundation's, made at genesis — is carried in through `secret accept`, because the mesh cannot
// invent a credential that already created the databases (the same reasoning as the control plane's
// store connections, control.go deliverStores).
func InstallStore(ctx context.Context, o Options, control controlPlane,
	foundation *declaration.Declaration, say func(string)) error {

	const module = "postgres"
	manifest, err := readManifest(o.Catalogue, module)
	if err != nil {
		return err
	}

	store, err := storeIn(foundation)
	if err != nil {
		return err
	}

	// The module adopts the running store rather than raising a second one, so its server container
	// has to BE the foundation's — same name, same image. The applier keys on the name and compares
	// a spec digest (internal/apply), so a mismatch here would not adopt the mesh's memory but
	// replace it. Checked before anything is registered, so a drift between the two pinned upstream
	// images (the catalogue's and the foundation bundle's) fails fast and by name, rather than
	// surfacing as the mesh's store being torn down and recreated.
	//
	// Not rewritten to the foundation's: the server image travels through the builder, which reads
	// the manifest from the repository and leaves a concrete image alone but would carry a rewrite
	// nowhere. The two are kept equal at the source — one pinned postgres, named in both places.
	if err := serverMatchesFoundation(manifest, store, module); err != nil {
		return err
	}
	say("  adopting          " + store.Name + " — the store the foundation raised, unchanged")

	// The superuser is the foundation's, made at genesis — carried in before the push, or the push
	// would seal random bytes where a working password has to be and the provisioner would not open
	// the store it is meant to manage.
	if err := installProvider(ctx, o, control, module, manifest, "(the provisioner; the server is adopted, not built)",
		func() error {
			return deliverCredential(ctx, o, control, module, "superuser", StoreSuperuserFile, "the store's superuser", say)
		},
		say); err != nil {
		return err
	}
	say("  adopted           " + store.Name + " — the foundation's store is now the " + module + " module")
	return nil
}

// installProvider registers, builds, issues, assigns and pushes one catalogue module, with one
// thing done just before the push — the moment a credential the mesh could not have made has to
// be in it. InstallFromCatalogue is the same sequence without that moment; the store, the broker
// and the vault each need it or need the shape, and three copies of it drifted.
func installProvider(ctx context.Context, o Options, control controlPlane, module string,
	manifest []byte, buildNote string, beforePush func() error, say func(string),
	send ...func() error) error {

	remote := "/" + module + "-module.json"
	if err := control.carrying(ctx, module+"-module.json", manifest, remote); err != nil {
		return err
	}
	if _, err := control.tell(ctx, "module", "add", remote); err != nil {
		return err
	}
	say("  registered        " + module)

	if o.CatalogSource.Repository == "" {
		return fmt.Errorf("%s has to be built and there is no --catalog-source to build it from: "+
			"the catalogue CHECKOUT says what it is, the catalogue REPOSITORY is where a builder "+
			"clones it", module)
	}
	say(strings.TrimRight("  building          "+module+" "+buildNote, " "))
	if _, err := control.within(buildWait).tell(ctx, "build", o.CatalogSource.Repository,
		"--path", "modules/"+module, "--ref", refOr(o.CatalogSource.Ref), "--wait", "1200s"); err != nil {
		return err
	}

	if _, err := control.tell(ctx, "module", "issue", module, "--node", o.Node); err != nil {
		say("  no account        " + module + " — it declares nothing to say on the broker")
	} else {
		say("  account issued    " + module)
	}

	if _, err := control.tell(ctx, "assign", o.Node, module); err != nil {
		return err
	}
	if err := prepareModule(ctx, o, control, module, say); err != nil {
		return err
	}
	if beforePush != nil {
		if err := beforePush(); err != nil {
			return err
		}
	}
	// A module whose first send is not a plain push says how it is sent: the bus, whose replacement is a
	// planned step (ADR 0236), is sent by that step (adoptTheBus).
	if len(send) > 0 && send[0] != nil {
		return send[0]()
	}
	_, err := pushNode(ctx, o, control, say)
	return err
}

// deliverCredential carries a credential genesis made into a module as its own secret, through
// `secret accept`: the mesh cannot invent the value a running server already has.
func deliverCredential(ctx context.Context, o Options, control controlPlane, module, secret, file, what string,
	say func(string)) error {

	value, err := readCredentialFile(file)
	if err != nil {
		return fmt.Errorf("%s is not at %s, so the %s module has nothing to open its server with — "+
			"and the mesh cannot invent the one the server already has: %w", what, file, module, err)
	}
	at := "/accepting-" + secret
	if err := control.carryingSecret(ctx, "mesh-accepting-"+secret, []byte(value), at); err != nil {
		return err
	}
	if _, err := control.tell(ctx, "secret", "accept", o.Node, module, secret, "--from", at); err != nil {
		return err
	}
	say("  accepted          " + secret + " — " + what + ", as genesis made it")
	return nil
}

// BusModule is the module the foundation's bus is adopted as (novox/hq ADR 0331 §1). The previous
// broker's module, lavinmq, left the catalogue with the move to one bus (ADR 0131).
const BusModule = "nats"

// InstallBroker makes the foundation's bus the `nats` module, adopted in place — the same shape as
// InstallStore, for the same reasons: the bus holds the mesh's streams, so it is kept, and from the
// module's first push the bus's user list reaches it in the module's declaration like any module's
// (ADR 0331 §1, §5). The installer's own placing of that list (enrol.go placeTheBusUsers) was the
// bridge to here and is not run again.
//
// **The bundle raises the bus where the module keeps it** (novox/hq ADR 0333 §1): the same container
// name, the same streams directory, configuration directory, user list and certificate. That is checked
// here against the module's own manifest before anything is registered, and a difference is refused
// naming each one — under another name or on other paths the module would raise a second bus beside the
// first, or an empty one in its place.
//
// **The image is the one thing that changes, once** (ADR 0333 §3). The store's module pins the upstream
// postgres the foundation runs; the bus's module builds its server image (it carries the mesh's snapshot
// tool), so no pinned reference can be equal to the foundation's. The applier recreates the container on
// the module's image, on the same streams, users and certificate. The mesh replaces its bus only as a
// planned step (ADR 0236), so the module is sent by that step: its streams snapshotted first, the restart
// said, and the installer waits until the container runs the module's image, the bus answers, and the
// controller ends the step done (bus_adoption.go), so nothing after this step dials a bus that is restarting.
func InstallBroker(ctx context.Context, o Options, control controlPlane,
	foundation *declaration.Declaration, fetch func(context.Context, string) (int, string, error),
	say func(string)) error {

	const module = BusModule
	manifest, err := readManifest(o.Catalogue, module)
	if err != nil {
		return err
	}
	bus, err := brokerIn(foundation)
	if err != nil {
		return err
	}
	if err := busLayoutIsTheModules(manifest, foundation, module); err != nil {
		return err
	}
	say("  adopting          " + bus.Name + " — the bus the foundation raised, its streams kept")
	if err := installProvider(ctx, o, control, module, manifest, "(the server, adopting the foundation's bus)",
		nil, say, func() error { return adoptTheBus(ctx, o, control, bus, say) }); err != nil {
		return err
	}
	if err := waitForTheAdoptedBus(ctx, o, control, bus, fetch, say); err != nil {
		return err
	}
	if err := waitForTheBusStep(ctx, o, control, say); err != nil {
		return err
	}
	say("  adopted           " + bus.Name + " — the foundation's bus is now the " + module +
		" module, and its user list is the module's from here on")
	return nil
}

// busMonitor is where the bus says it is healthy: its monitoring port, published on the machine's own
// loopback by the bundle and by the module alike (both "127.0.0.1:8222:8222"). /healthz answers ok only
// once the server is up and JetStream has its streams back.
const busMonitor = "http://127.0.0.1:8222/healthz"

// runningImage is the image the named container was created from, or "" when there is none.
func runningImage(ctx context.Context, control controlPlane, name string) string {
	asking, cancel := context.WithTimeout(ctx, control.timeout)
	defer cancel()
	out, err := control.run(asking, "docker", "inspect", "--format", "{{.Config.Image}}", name)
	if err != nil {
		return ""
	}
	return strings.TrimSpace(out)
}

// waitForTheAdoptedBus waits until the bus container runs an image other than the one the bundle raised
// it from — the module's, after the applier's one recreate — and the bus answers on its monitor.
//
// Bounded by --wait, and asked at least once. A bus still on the bundle's image when it runs out is
// refused, naming what it runs: the push was sent and the node has not applied it, and every step after
// this one reaches the mesh through that bus.
func waitForTheAdoptedBus(ctx context.Context, o Options, control controlPlane, bus *declaration.Container,
	fetch func(context.Context, string) (int, string, error), say func(string)) error {

	deadline := time.Now().Add(o.Wait)
	var running, said string
	for {
		running = runningImage(ctx, control, bus.Name)
		if running != "" && running != bus.Image {
			code, body, err := fetch(ctx, busMonitor)
			if err == nil && code == http.StatusOK {
				say("  bus answers       " + bus.Name + " on " + running)
				return nil
			}
			said = strings.TrimSpace(body)
			if err != nil {
				said = err.Error()
			}
		}
		if !time.Now().Before(deadline) {
			break
		}
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-time.After(answerEvery):
		}
	}
	switch {
	case running == "":
		return fmt.Errorf("the bus container %s is not there after the %s module was pushed, so nothing "+
			"after this step could reach the mesh. The node-engine's journal says why it did not raise it",
			bus.Name, BusModule)
	case running == bus.Image:
		return fmt.Errorf("%s still runs the bundle's image %s %s after the %s module was pushed: the node "+
			"has not applied it. Its streams are untouched; run this installer again once the node-engine "+
			"applies (its journal says why it did not)", bus.Name, bus.Image, o.Wait, BusModule)
	}
	return fmt.Errorf("%s runs the %s module's image %s and its monitor (%s) did not answer ok within %s: %s",
		bus.Name, BusModule, running, busMonitor, o.Wait, orUnknown(said))
}

// BusUsersID is the bundle's resource for the bus's first user list.
const BusUsersID = "bus-accounts"

// busLayout is where a bus lives: its container, the machine's directories it mounts as its streams,
// its configuration and its certificate, and the file its user list is.
type busLayout struct {
	Container, Streams, Conf, Certificate, Users string
}

// Where the server reads each, inside its container: the same in the bundle and the module, since both
// run the same server with the same configuration.
const (
	busStreamsInside     = "/data"
	busConfInside        = "/etc/nats"
	busCertificateInside = "/tls"
)

// foundationBusLayout reads the layout of the bus the bundle raises.
func foundationBusLayout(foundation *declaration.Declaration) (busLayout, error) {
	bus, err := brokerIn(foundation)
	if err != nil {
		return busLayout{}, err
	}
	at := mountedFrom(bus.Volumes)
	l := busLayout{Container: bus.Name, Streams: at[busStreamsInside], Conf: at[busConfInside],
		Certificate: at[busCertificateInside]}
	for _, r := range foundation.Resources {
		if f, ok := r.(*declaration.File); ok && r.Identity() == BusUsersID {
			l.Users = f.Path
		}
	}
	return l, nil
}

// moduleBusLayout reads the layout of the bus the module declares: its server container, the mounts of
// that container with every `${access:<id>}` resolved to the access's path, and its `bus-users`.
func moduleBusLayout(manifest []byte, module string) (busLayout, error) {
	var m struct {
		BusUsers  string `json:"bus-users"`
		Resources []struct {
			ID      string   `json:"id"`
			Type    string   `json:"type"`
			Name    string   `json:"name"`
			Volumes []string `json:"volumes"`
		} `json:"resources"`
		Accesses []struct {
			ID   string `json:"id"`
			Path string `json:"path"`
		} `json:"accesses"`
	}
	if err := json.Unmarshal(manifest, &m); err != nil {
		return busLayout{}, fmt.Errorf("the %s module's manifest is not readable: %w", module, err)
	}
	var containers []int
	for i, r := range m.Resources {
		if r.Type == "container" {
			containers = append(containers, i)
		}
	}
	if len(containers) != 1 {
		var names []string
		for _, i := range containers {
			names = append(names, m.Resources[i].Name)
		}
		return busLayout{}, fmt.Errorf("the %s module declares %s; the bus it adopts is one server, so it "+
			"declares one container", module, describeNames(names))
	}
	server := m.Resources[containers[0]]
	resolved := make([]string, 0, len(server.Volumes))
	for _, v := range server.Volumes {
		for _, a := range m.Accesses {
			v = strings.ReplaceAll(v, "${access:"+a.ID+"}", a.Path)
		}
		resolved = append(resolved, v)
	}
	at := mountedFrom(resolved)
	return busLayout{Container: server.Name, Streams: at[busStreamsInside], Conf: at[busConfInside],
		Certificate: at[busCertificateInside], Users: m.BusUsers}, nil
}

// busLayoutIsTheModules checks that the bus the bundle raised is where the module keeps it, field by
// field, so the applier takes it over rather than raising a second bus beside it or an empty one in its
// place (novox/hq ADR 0333 §1). Every difference is named, with both sides.
func busLayoutIsTheModules(manifest []byte, foundation *declaration.Declaration, module string) error {
	theirs, err := moduleBusLayout(manifest, module)
	if err != nil {
		return err
	}
	ours, err := foundationBusLayout(foundation)
	if err != nil {
		return err
	}
	var differ []string
	for _, f := range []struct{ what, module, bundle string }{
		{"the server container", theirs.Container, ours.Container},
		{"its streams (" + busStreamsInside + ")", theirs.Streams, ours.Streams},
		{"its configuration (" + busConfInside + ")", theirs.Conf, ours.Conf},
		{"its certificate (" + busCertificateInside + ")", theirs.Certificate, ours.Certificate},
		{"its user list", theirs.Users, ours.Users},
	} {
		if f.module == "" || f.module != f.bundle {
			differ = append(differ, fmt.Sprintf("%s: the module's is %q, the bundle's %q", f.what,
				f.module, f.bundle))
		}
	}
	if len(differ) == 0 {
		return nil
	}
	return fmt.Errorf(
		"the bus the foundation raised is not where the %s module keeps it:\n  - %s\n"+
			"The module adopts the foundation's bus in place, so the bundle raises it with the module's "+
			"name and paths; otherwise adopting it would raise a second bus beside the first, or an empty "+
			"one on other paths (novox/hq ADR 0333 §1). Nothing has been registered",
		module, strings.Join(differ, "\n  - "))
}

func describeNames(names []string) string {
	if len(names) == 0 {
		return "no container at all"
	}
	return "the containers " + strings.Join(names, ", ")
}

// InstallVault installs the vault as a foundation module (novox/hq ADR 0085, amended). Nothing to
// adopt and nothing to carry in: it is its own runtime, built from the catalogue like any provider,
// and from its first push it keeps the export of every operator-sealed secret on its own disk.
func InstallVault(ctx context.Context, o Options, control controlPlane, say func(string)) error {
	const module = "mesh-vault"
	manifest, err := readManifest(o.Catalogue, module)
	if err != nil {
		return err
	}
	if err := installProvider(ctx, o, control, module, manifest, "", nil, say); err != nil {
		return err
	}
	say("  installed         " + module + " — the operator-sealed export now lives on this machine, outside the store")
	return nil
}

// storeIn finds the store container in the bundle this installer produced.
func storeIn(d *declaration.Declaration) (*declaration.Container, error) {
	return foundationContainer(d, StoreID, "store")
}

// brokerIn finds the bus's container in the bundle this installer produced.
func brokerIn(d *declaration.Declaration) (*declaration.Container, error) {
	return foundationContainer(d, BrokerID, "bus")
}

func foundationContainer(d *declaration.Declaration, id, what string) (*declaration.Container, error) {
	for _, r := range d.Resources {
		if r.Identity() != id {
			continue
		}
		container, ok := r.(*declaration.Container)
		if !ok {
			return nil, fmt.Errorf(
				"this bundle's %q is a %s, not a container, so the %s module has nothing to adopt",
				id, r.Kind(), what)
		}
		return container, nil
	}
	return nil, fmt.Errorf(
		"this bundle names no %q, so there is no %s for a module to adopt. It declares: %s",
		id, what, strings.Join(identities(d), ", "))
}

// serverMatchesFoundation checks that the module's adopting container is the one the foundation
// raised — same name, same image — so the applier reconciles it in place rather than replacing it.
func serverMatchesFoundation(manifest []byte, store *declaration.Container, module string) error {
	var m struct {
		Resources []struct {
			Type  string `json:"type"`
			Name  string `json:"name"`
			Image string `json:"image"`
		} `json:"resources"`
	}
	if err := json.Unmarshal(manifest, &m); err != nil {
		return fmt.Errorf("the %s module's manifest is not readable: %w", module, err)
	}
	for _, r := range m.Resources {
		if r.Type != "container" || r.Name != store.Name {
			continue
		}
		if r.Image != store.Image {
			return fmt.Errorf(
				"the %s module's %q container is pinned to %q, and the foundation is running %q.\n"+
					"The module adopts the foundation's store in place, so the two must name the same "+
					"image — a different one would tear down the mesh's store and raise a new one on "+
					"its data. Pin both to the same postgres image",
				module, store.Name, r.Image, store.Image)
		}
		return nil
	}
	return fmt.Errorf(
		"the %s module declares no container named %q, so it has nothing to adopt the foundation's "+
			"store with. Its server container has to carry the name the foundation raised",
		module, store.Name)
}