package resolution

import (
	"encoding/json"
	"fmt"
	"sort"
	"strings"

	mcat "git.novox.be/novox/mesh-sdk/go/catalogue"
)

// BundleID names the archive resource that delivers one of a module's bundles; prefixed with the
// module like every resource of its own.
func BundleID(bundle string) string { return "bundle-" + bundle }

// BundlePath is where one module's bundle is unpacked on a machine.
func BundlePath(module, bundle string) string { return mcat.BundleRoot + "/" + module + "/" + bundle }

// runtimeHere says whether this node's set includes the runtime module, which is what decides
// whether anything about tools changes on the machine (to-be 38 WP2): until the runtime is assigned,
// a node is sent exactly what it was sent before, bundles included, because a bundle nothing loads
// is bytes nobody reads.
func resolutionRuntimeHere(r mcat.Resolution) bool {
	for _, m := range r.Modules {
		if m.Module == mcat.RuntimeModule {
			return true
		}
	}
	return false
}

// bundleArchives is one archive per tools bundle of a module — a bundle the runtime LOADS something
// from — as the host fetches and unpacks any artifact (novox/hq ADR 0175 §3: a module brings its
// tools as a bundle, delivered by the host like any artifact, never an image). A bundle it loads
// nothing from is run rather than loaded: a daemon, a step, the runtime itself — delivered by the
// process that runs it, and not again here.
//
// The source is the kept reference; the per-resource pass that follows routes it through the
// artifact store as this network reaches it now, as it does every image and archive the mesh built.
func bundleArchives(m mcat.Manifest) []map[string]any {
	var out []map[string]any
	for _, b := range m.Bundles {
		if len(b.Loads) == 0 {
			continue
		}
		out = append(out, map[string]any{
			"id": BundleID(b.Name), "type": "archive",
			"source": b.Source, "digest": b.Digest,
			"path": BundlePath(m.Module, b.Name),
		})
	}
	return out
}

// RuntimeProcessID names the one process the mesh composes for a machine's runtime; prefixed with
// the runtime module like a resource of its own, because that module is what the host sees it as.
func RuntimeProcessID() string { return "runtime" }

// interpreterFor is how a bundle in a language is run: the program the host's unit starts, with the
// bundle's entrypoint after it. The one thing the composer takes from a language, and said here
// rather than in a manifest because the runtime's process is the mesh's to compose (to-be 38 WP3).
func interpreterFor(language string) (string, error) {
	switch language {
	case "typescript":
		return "node", nil
	}
	return "", fmt.Errorf(
		"%s is written in %q, and the mesh knows no interpreter to run a %q bundle with", mcat.RuntimeModule, language, language)
}

// runtimeProcess is the one process a machine runs the node's tool runtime as (novox/hq ADR 0175,
// to-be 38 WP2.3): the runtime module's own bundle, run by its language's interpreter, told which
// modules it serves and from which files, where its credential is, and who the machine's operator
// is — and restarted when any bundle it loads or the credential it holds changes.
//
// Composed from the placed manifests, so the credential's path is where this node puts it. The
// runtime runs as the operator's account when the machine has one, which is what lets a tool that
// needs root escalate as the operator would (ADR 0175 §4); on a machine with no account it runs as
// root, and the two operator words are not set.
func resolutionRuntimeProcess(r mcat.Resolution, with mcat.Rendering) (map[string]any, error) {
	var runtime *mcat.Manifest
	for i := range r.Modules {
		if r.Modules[i].Module == mcat.RuntimeModule {
			runtime = &r.Modules[i]
		}
	}
	if runtime == nil || runtime.Stubbed {
		// Held (its stand-in, Stubbed): its process is never applied, what runs of it is carried, and its stand-in is
		// never refused by a rule about its bundle or its broker (issue 774: node-tools held for a build not done, then
		// "its build produced 0 bundle(s)", refused every module of ace, g14 and shanks).
		return nil, nil
	}
	if len(runtime.Bundles) != 1 {
		return nil, fmt.Errorf(
			"%s is assigned to %s and its build produced %d bundle(s); the runtime is one bundle "+
				"the mesh runs, so the module declares exactly one (novox/hq to-be 38)", mcat.RuntimeModule, r.Node, len(runtime.Bundles))
	}
	bundle := runtime.Bundles[0]
	// What runs it (novox/hq ADR 0193): a runtime compiled to a binary runs itself, from its own
	// unpacked bundle; an interpreted one is its language's interpreter and its one entrypoint.
	var run []any
	if bundle.Binary != "" {
		run = []any{"./" + bundle.Binary}
	} else {
		if len(bundle.Entrypoints) != 1 {
			return nil, fmt.Errorf(
				"%s's bundle %q names %d entrypoint(s); the runtime is run from one, so the module "+
					"declares exactly one (novox/hq to-be 38)", mcat.RuntimeModule, bundle.Name, len(bundle.Entrypoints))
		}
		interpreter, err := interpreterFor(bundle.Language)
		if err != nil {
			return nil, err
		}
		run = []any{interpreter, bundle.Entrypoints[0]}
	}
	credential, declared := runtime.OwnSecrets["broker"]
	if !declared {
		return nil, fmt.Errorf(
			"%s declares no own secret named broker, and the node's credential is delivered there: "+
				"a module that speaks on the bus declares \"own-secrets\": {\"broker\": <path>}", mcat.RuntimeModule,
		)
	}

	// What it serves, and from which files: every module on this machine that composes here, in
	// name order, each bundle it loads from in the order the manifest gave. A module left out of
	// the declaration — a filter on an adopted machine — is left out of this too, or the runtime
	// would be told to load files that were never delivered.
	var served []string
	var restartOn []string
	given := map[string]map[string]string{}
	for _, m := range r.Modules {
		if with.Adopted && m.Filtering != nil {
			continue
		}
		if m.RunsAs != "" {
			// Served by a runtime of its own, on its own account (ownRuntimes): never the machine's.
			continue
		}
		words, err := bundleWords(m, with)
		if err != nil {
			return nil, err
		}
		// The holder of node-files is told the same, and the paths modules own here (novox/hq ADR 0394 §4).
		if words, err = resolutionFilesWords(r, m, words, with); err != nil {
			return nil, err
		}
		if len(words) > 0 {
			given[m.Module] = words
		}
		for _, b := range m.Bundles {
			if len(b.Loads) == 0 {
				continue
			}
			for _, load := range b.Loads {
				// What the runtime starts: the launcher the build wrote beside the entrypoint, where
				// it wrote one (ADR 0193); the entrypoint itself for a build from before them.
				if launcher, has := b.Launchers[load]; has {
					load = launcher
				}
				served = append(served, m.Module+"="+BundlePath(m.Module, b.Name)+"/"+load)
			}
			restartOn = append(restartOn, m.Module+"."+BundleID(b.Name))
		}
	}
	sort.Strings(served)
	restartOn = append(restartOn, mcat.RuntimeModule+"."+mcat.NeedID("broker"))
	sort.Strings(restartOn)

	env := map[string]string{mcat.RuntimeToolModules: strings.Join(served, ","), mcat.RuntimeBrokerFile: credential.Path}
	if len(given) > 0 {
		// Marshalled from maps, whose keys encoding/json sorts: the same words, the same unit.
		body, err := json.Marshal(given)
		if err != nil {
			return nil, err
		}
		env[mcat.RuntimeToolEnv] = string(body)
	}
	process := map[string]any{
		"id": mcat.RuntimeModule + "." + RuntimeProcessID(), "type": "process", "name": mcat.RuntimeModule,
		"source": bundle.Source, "digest": bundle.Digest,
		"run":        run,
		"env":        env,
		"restart-on": toAny(restartOn),
	}
	if r.Account != "" {
		env[mcat.RuntimeOperatorAccount] = r.Account
		env[mcat.RuntimeOperatorHome] = accountHomeOf(r.Account, r.AccountHome)
		process["user"] = r.Account
	}
	if agent, home := resolutionAgentAccount(r); agent != "" {
		env[mcat.RuntimeAgentAccount] = agent
		env[mcat.RuntimeAgentHome] = home
	}
	// Routed through the artifact store as this network reaches it now, like everything the mesh
	// built; refused with the same words when there is no store to route through.
	if err := artifactsInto(process, mcat.RuntimeModule, with); err != nil {
		return nil, err
	}
	return process, nil
}

// NoRuntimeToRunError is a module of its own account with no runtime program on its node to run it from. Held says the
// runtime is there and held (its stand-in, Stubbed): the module cannot compose because the runtime does not, so a
// composition that holds the runtime holds it too, never the node (issue 774).
type NoRuntimeToRunError struct {
	Held bool
	said string
}

func (e *NoRuntimeToRunError) Error() string { return e.said }

// ownRuntimes are the processes the modules of their own account are served by (novox/hq ADR 0259 §8): each
// the machine's runtime program — the same build, run from the same source — serving that one module alone,
// as the module's own account, on the module's own bus credential. Never the machine's runtime, which runs
// as the operator's account and carries every module on the machine.
func resolutionOwnRuntimes(r mcat.Resolution, with mcat.Rendering) ([]map[string]any, error) {
	var own []mcat.Manifest
	for _, m := range r.Modules {
		// A held module's stand-in (Stubbed) has no runtime of its own composed, and so none of this function's rules
		// about one: none of its composition is applied, and what runs of it is carried as it runs. Refusing it here
		// refused its whole node (issue 774, 2026-10-30 21:04: mesh-self-check, held for its broker not made, then
		// "runs as its own account and declares no own secret broker", failed 74 modules on ace and 79 on novox).
		if m.RunsAs != "" && !m.Stubbed && !(with.Adopted && m.Filtering != nil) {
			own = append(own, m)
		}
	}
	if len(own) == 0 {
		return nil, nil
	}
	var runtime *mcat.Manifest
	for i := range r.Modules {
		if r.Modules[i].Module == mcat.RuntimeModule {
			runtime = &r.Modules[i]
		}
	}
	if runtime == nil || len(runtime.Bundles) != 1 || runtime.Bundles[0].Binary == "" {
		return nil, &NoRuntimeToRunError{Held: runtime != nil && runtime.Stubbed, said: fmt.Sprintf("%s runs as its own "+
			"account in a runtime of its own, and %s is not here to run it from: assign %s to %s first (novox/hq ADR 0259)",
			own[0].Module, mcat.RuntimeModule, mcat.RuntimeModule, r.Node)}
	}
	program := runtime.Bundles[0]
	var out []map[string]any
	for _, m := range own {
		// Never the node's operator account, nor the account agents run as there (the review of 2026-10-09):
		// either would hand what it holds back to the very accounts it is kept from.
		switch {
		case r.Account != "" && m.RunsAs == r.Account:
			return nil, fmt.Errorf("%s runs as %s, the operator's account on %s: a module of its own account never "+
				"runs as it (novox/hq ADR 0259 §8)", m.Module, m.RunsAs, r.Node)
		case r.AgentAccount != "" && m.RunsAs == r.AgentAccount:
			return nil, fmt.Errorf("%s runs as %s, the account agents run as on %s: a module of its own account "+
				"never runs as it (novox/hq ADR 0259 §8)", m.Module, m.RunsAs, r.Node)
		}
		credential, declared := m.OwnSecrets["broker"]
		if !declared {
			return nil, fmt.Errorf("%s runs as its own account and declares no own secret broker", m.Module)
		}
		var served, restartOn []string
		for _, b := range m.Bundles {
			for _, load := range b.Loads {
				if launcher, has := b.Launchers[load]; has {
					load = launcher
				}
				served = append(served, m.Module+"="+BundlePath(m.Module, b.Name)+"/"+load)
			}
			if len(b.Loads) > 0 {
				restartOn = append(restartOn, m.Module+"."+BundleID(b.Name))
			}
		}
		if len(served) == 0 {
			return nil, fmt.Errorf("%s runs as its own account and its build produced no bundle to serve", m.Module)
		}
		sort.Strings(served)
		restartOn = append(restartOn, m.Module+"."+mcat.NeedID("broker"))
		sort.Strings(restartOn)
		env := map[string]string{mcat.RuntimeToolModules: strings.Join(served, ","), mcat.RuntimeBrokerFile: credential.Path}
		words, err := bundleWords(m, with)
		if err != nil {
			return nil, err
		}
		// The holder of node-reads is told where this node keeps its secrets (novox/hq ADR 0310 §5).
		if words, err = resolutionReadsWords(r, m, words, with); err != nil {
			return nil, err
		}
		// A build seat's holder gives way on its node, and its steps are told their part of the node's share
		// (novox/hq ADR 0553).
		yielding, yieldWords := resolutionYieldsOf(r, m, with)
		if len(yieldWords) > 0 {
			if words == nil {
				words = map[string]string{}
			}
			for k, v := range yieldWords {
				words[k] = v
			}
		}
		if len(words) > 0 {
			body, err := json.Marshal(map[string]map[string]string{m.Module: words})
			if err != nil {
				return nil, err
			}
			env[mcat.RuntimeToolEnv] = string(body)
		}
		process := map[string]any{
			"id": m.Module + "." + mcat.OwnRuntimeID(), "type": "process", "name": m.Module + "-runtime",
			"source": program.Source, "digest": program.Digest,
			"run": []any{"./" + program.Binary}, "env": env, "restart-on": toAny(restartOn),
			"user": m.RunsAs,
		}
		// How it is ready, as the module declared it (novox/hq ADR 0366 §1), in the node-engine's words.
		if _, has := mcat.OwnRuntimeHealth(m); has {
			process[mcat.HealthField] = m.RuntimeHealth
			healthInto(process, m, with)
		}
		if yielding != nil {
			process["yields"] = yielding
		}
		if err := artifactsInto(process, mcat.RuntimeModule, with); err != nil {
			return nil, err
		}
		out = append(out, process)
	}
	return out, nil
}

func toAny(in []string) []any {
	out := make([]any, 0, len(in))
	for _, s := range in {
		out = append(out, s)
	}
	return out
}

// bundleWords is what one module's tools bundles are given on this machine (novox/hq ADR 0192):
// each loaded bundle's env, its ${dir:…} resolved to where this machine places the module's
// directories and its ${port:…} to the port this machine gave it — the same resolution a
// container's environment gets. Two bundles of one module naming one word differently is refused:
// the runtime hands a module's words to all its bundles.
func bundleWords(m mcat.Manifest, with mcat.Rendering) (map[string]string, error) {
	var out map[string]string
	dirs := dirsFor(m, with)
	for _, b := range m.Bundles {
		if len(b.Loads) == 0 || len(b.Env) == 0 {
			continue
		}
		for _, word := range sortedKeys(b.Env) {
			value, err := dirFill(b.Env[word], dirs, m.Module)
			if err != nil {
				return nil, err
			}
			if value, err = portsFilledInto(value, m.Module+"'s bundle "+b.Name+" ("+word+")", m.Module, m.Listens, with); err != nil {
				return nil, err
			}
			if out == nil {
				out = map[string]string{}
			}
			if was, had := out[word]; had && was != value {
				return nil, fmt.Errorf("%s's bundles give %s two values (%q, %q); a module's words are "+
					"handed to all its bundles, so they agree (novox/hq ADR 0192)", m.Module, word, was, value)
			}
			out[word] = value
		}
	}
	return out, nil
}

// givenTo makes what a bundle's words name readable by the account the runtime runs as (novox/hq
// ADR 0192): every file and directory of the module whose path a word names, or that holds one,
// is owned by the account — a tool reads its configuration and its secret as the account, and a
// root-owned 0600 file or a 0700 directory is one it cannot. Only where it says no owner already:
// a module that named one knew why. Nothing on a machine with no account, where the runtime is root.
//
// It answers the files a word names exactly: what a tool reads, whose change the runtime must be
// restarted for, as the container the tools came from was restarted when its configuration changed.
func givenTo(out []map[string]any, owner map[string]string, words map[string]map[string]string, account string) []string {
	var named []string
	if len(words) == 0 {
		return nil
	}
	for _, resource := range out {
		module := owner[fmt.Sprint(resource["id"])]
		mine := words[module]
		if len(mine) == 0 {
			continue
		}
		kind := fmt.Sprint(resource["type"])
		if kind != "file" && kind != "directory" {
			continue
		}
		path, _ := resource["path"].(string)
		if path == "" {
			continue
		}
		for _, value := range mine {
			if kind == "file" && value == path {
				named = append(named, fmt.Sprint(resource["id"]))
			}
		}
		if _, said := resource["owner"]; said || account == "" {
			continue
		}
		for _, value := range mine {
			if value == path || strings.HasPrefix(value, strings.TrimRight(path, "/")+"/") {
				resource["owner"] = account
				break
			}
		}
	}
	sort.Strings(named)
	return named
}