package catalogue

import (
	"encoding/json"
	"sort"
	"strconv"
	"strings"
	"time"
)

// SettingsBy is the layers that apply to each module, keyed by module name.
type SettingsBy map[string][]Layer

// Generator works out a module's resources for one node, where they cannot be written in advance.
type Generator interface {
	// Resources for this node. Absent means the node is not part of whatever this generates,
	// which is an ordinary answer rather than a failure — a machine assigned the module before it
	// has an address on the network is in exactly that state.
	Resources(node string) ([]map[string]any, bool, error)
}

// OpensPorts is a generator that also says what its resources accept connections on.
//
// **Separate from Generator, because most generators have nothing to say here** and requiring an
// empty method of each would be a cost paid everywhere for one caller.
//
// It exists because a static field cannot express this. A hub accepts connections from every node
// at other sites; a machine that is not a hub dials out and needs nothing open — and they are the
// same module. `listens` in a manifest is one answer for every machine that runs it, so the
// machine that most needs filtering, the one facing the public internet, was the one whose rule
// set would have closed its own overlay.
type OpensPorts interface {
	// Listens is what this node accepts on because of what was computed for it. Nothing is the
	// ordinary answer: most machines running a computed module open no port at all.
	Listens(node string) ([]Listening, error)
}

// Grant is one consumer's credential, on the machine that must create it.
type Grant struct {
	// Provision is what was required.
	Provision string
	// Consumer is the node that will use it.
	Consumer string
	// From is the module on that machine which asked.
	//
	// **Part of who this credential is for, not a label** (novox/hq 04-ISSUES/022). Together with
	// Consumer it names one consumer; the node alone does not, because a machine routinely runs
	// several modules wanting the same thing. It is also what the provider names the role or the
	// bucket or the client after, so withdrawing one consumer does not take another's away.
	From string
	// Values are what that module contributed — the name it wants, and anything else the
	// provision's own vocabulary defines.
	Values map[string]any
	// Local is the name the credential goes by inside the consumer where it keeps several for one
	// provision (ADR 0094); empty for the ordinary one. The provider sees it as a holder of its own.
	Local string
	// Slug is the consumer module's identity slug, if it declared one — carried on the grant so the
	// provider side derives the same login the consumer does, even across nodes where the consumer's
	// manifest is not in view (novox/hq ADR 0049). Empty means "use the module name".
	Slug string
	// At is where the consuming machine is on the private network, empty if it is not on one.
	//
	// Passed in with the grant because it is a fact about another machine, and resolution answers
	// questions about one. A provider that must reach back to its consumer — a reverse proxy is
	// the whole reason this exists — otherwise has to know how the mesh names machines.
	At string
	// Sealed is the credential, closed to the providing node.
	Sealed string
}

// Rendering is everything needed to turn a resolution into the declaration a node is sent.
type Rendering struct {
	// Certificate is what the mesh issued for this machine's internal name, and the mesh's own
	// certificate. Both public — the key they belong to never left the machine.
	Certificate string
	Authority   string

	// Needed is each module's own secrets, sealed to this node, keyed by module and then by the
	// name the module gave it.
	Needed map[string]map[string]string
	// Foreseen is each own secret not made yet that the next send WILL make, keyed like Needed: a
	// composition asked ahead of the send (the self-check's D1) composes it with ForeseenSealed in
	// its place and lists it in Composed.Foreseen, rather than failing for a value only a send
	// makes. Nil on every composition that is sent, and on every other question, which then refuse
	// a secret not made with a *NotMadeError.
	Foreseen map[string]map[string]bool
	// VaultSealed is, for a module on the core's list (CoreCredentialModules), each own secret as the vault sealed it
	// to this machine (the mesh's sealed box, as the vault answered it), keyed like Needed (novox/hq ADR 0349 §16,
	// issue 755). Given only for a machine whose engine opens the box (VaultBoxContract): its file then carries the
	// box and never the controller's own sealed value. Nil everywhere else, and the composition is as it was.
	VaultSealed map[string]map[string]json.RawMessage
	// NotPlaced is each core module left out of this machine's declaration because the vault gave nothing for its
	// credential and no box was kept, with why (issue 755): the machine keeps what it holds of it, and a module not
	// yet there is not placed. Nil everywhere else.
	NotPlaced map[string]string

	// Mesh is every node's address on the private network, which is what a rule saying "from the
	// mesh" resolves to. Passed in for the same reason grants are: who else is on the network is
	// a fact about the mesh, and resolution answers questions about one machine.
	Mesh []string
	// Suffix is what a machine's internal name ends in, as the control plane composed Names —
	// `internal` unless the operator chose another — so a fact writing those names does not
	// compose it a second time.
	Suffix string

	// BusUsers is the mesh's composed user list, for the module holding `mesh-broker`. Empty on
	// every other node, and on this one until the controller has composed it.
	//
	// **Only the users, never the server's own settings**: those are the module's, in its image and
	// its mounts (Manifest.BusUsers).
	BusUsers string
	// BusMembership is this machine's membership for the bus the mesh is moving to, sealed to it
	// (design 28, task 5.2). Empty for a machine not being moved. Written as a file the host reads
	// after the declaration has applied, so the bus it names is standing before the machine leaves
	// the one it is on.
	BusMembership string

	// MeshRange is the private network's CIDR (the range node addresses are allocated from), for a
	// module that must name the whole mesh rather than one machine — an intrusion filter that must
	// never ban a tunnel peer, say. A per-mesh value the module cannot know, so it is carried here
	// and offered as ${machine:mesh-range}, the same way one machine's address is.
	MeshRange string

	// Accounts is each machine's operator account, by the same internal name Names uses (novox/hq
	// to-be 29). What an ssh Host block's `User` line is composed from; empty for a machine no
	// operator account is known on.
	Accounts map[string]string

	// Kept is every operator-sealed secret in the mesh, for a module that `keeps` them. Nil when
	// nothing on this node keeps them, or the mesh has no operator key.
	Kept *KeptExport
	// KeptRuns is, by module, the file of the export as the node runs it, for a composer that holds no export (a node
	// composing its own: the export is the controller's store's, issue 1126, C6): carried as it runs when Kept is nil.
	KeptRuns map[string]map[string]any

	// OutwardLinks is the links this machine reported as facing outside it, which the filter is
	// written around (novox/hq ADR 0140). Empty means the machine has not said, and the mesh
	// composes no filter for it rather than writing a rule around a link with no name.
	OutwardLinks []string

	// LocalNetworks is this machine's local networks (novox/hq ADR 0340): the networks it reported on a
	// link facing outside it that lie wholly in a private range (JudgeLocalNetworks), which a port
	// reached from `local-network` is admitted from beside the private network. Empty when it reported
	// none, and the rule set then says so rather than widening the port or dropping it.
	LocalNetworks []string

	// TunnelInterface is the interface the mesh's private network runs on, named here rather than
	// imported because the overlay package rests on this one. Traffic arriving on it is the mesh's,
	// not this machine's own guest, so the filter admits it only by a rule.
	TunnelInterface string

	// Foundation is the ports the mesh itself needs reachable on every machine, which no module
	// declares because the foundation is not a module (novox/hq 04-ISSUES/051 and 052). The broker
	// is the one that matters: a machine dials it to enrol, and a firewall derived only from
	// modules closes it.
	Foundation []int

	// Names is every machine's internal name and its address, for containers to be given.
	//
	// **A container does not inherit the machine's names**, so every internal name the mesh wrote
	// is invisible to what the machine runs. Given here rather than looked up on the machine,
	// because which machines exist is a fact about the mesh.
	Names map[string]string

	// Machines is only the machines, by the same internal name — the subset of Names that is a
	// node of this mesh rather than a name it was told to serve. Both matter and they are not the
	// same set: a container's hosts wants every name, so a routed name resolves to the proxy that
	// serves it, while a resolver told the mesh's suffix is authoritative for it answers from what
	// it is given and forwards nothing — so a routed name written there is a name nobody asks for,
	// standing beside the machines and looking as real as they do.
	Machines map[string]string

	// Zones is every zone a module in the mesh answers itself, where it is answered (novox/hq ADR
	// 0199): the mesh's resolver forwards each one there.
	Zones []ZoneAt

	// Holders is, for each replicated mesh seat, every machine holding it, by internal name and
	// private address (novox/hq ADR 0223) — the same shape as Machines. What a machine's resolver
	// file lists: every holder of the mesh's resolver, this machine first if it is one.
	Holders map[string]map[string]string

	Settings   SettingsBy
	Generators map[string]Generator
	// Grants are the credentials this node must create, for the provisions it offers. Passed in
	// rather than resolved, because who consumes a node is a fact about the rest of the mesh and
	// resolution answers questions about one machine.
	Grants []Grant
	// Withheld is every consumer left out of Grants because its identity overflows the provision's
	// bound (novox/hq ADR 0225). Composed into nothing; carried so the machine's declaration can say
	// whom it does not serve, and why, beside what it does.
	Withheld []Overflow
	// Unbound is every consumer whose pair credential from this node is on record and whose own
	// resolution binds it elsewhere (novox/hq issue 274): never granted, carried to be said.
	Unbound []Unbound

	// Ports is where this machine puts what each module needs reachable, by module and by the
	// port the software itself uses (novox/hq ADR 0038).
	//
	// **The one place the number now lives.** A module used to write it three times — for the rule
	// set, for what a consumer is told, and for what the runtime publishes — and nothing checked
	// that the three agreed. They are all derived from this.
	Ports map[string]map[int]int

	// Adopted says the node is adopted (novox/hq ADR 0100): the firewall found on it stays in
	// force, so no module that loads a filter is declared there, and what the mesh needs
	// reachable is declared as openings, with its own ports guarded by a table that only refuses.
	Adopted bool

	// Given is the machine ports this node was given for its modules' ports, by module and by the
	// port the software uses (novox/hq ADR 0100) — the foundation's ports, as genesis chose them.
	// They win over anything the mesh would assign and over a manifest's own long-form mapping.
	Given map[string]map[int]int

	// Planned says this rendering composes the plans the seat mesh-provisioner keeps (compose.Planning). A contribution a
	// plan carries is then refused where its port is none the module listens on: no machine port stands for it, and its
	// provider dials what the plan says (issue 774, research 072 row 34).
	Planned bool

	// Taken is the modules taken on this adopted node (novox/hq ADR 0100). The guard is derived
	// from these only (ADR 0103): a port of a module assigned but not taken may still be the
	// predecessor's.
	Taken map[string]bool

	// Seats is where this machine put each mesh-scoped seat's holder, by seat and by the port the
	// holder's software uses (novox/hq 04-ISSUES/102) — read from the node's settings and
	// assignments for whichever module claims the seat, whether or not it is in this node's set.
	// What ${seat:…} answers with; see seat_into.go for why the answer may be absent.
	Seats map[string]map[int]int

	// ArtifactStore is the mesh's artifact store as this network reaches it (host:port) — the
	// node holding it and the port that node put it on — or empty when the mesh has none on its
	// network yet. Composed into every image and archive the mesh built, at this moment and never
	// stored (novox/hq 04-ISSUES/102).
	ArtifactStore string

	// SeatReach is where this machine reaches the holder of each mesh-scoped seat it may be asked
	// about (host:port), by seat: what ${seat:<seat>:reach} answers with (novox/hq ADR 0222). Absent
	// when no holder is reachable yet; see seat_into.go for which seats are answered.
	SeatReach map[string]string

	// Built is every `<module>/<artifact>` the mesh has built. What tells a reference recorded
	// with an address — before references were kept without one — from an image a module runs
	// straight from a public registry.
	Built map[string]bool

	// DataRoot is where this node keeps the directories the mesh places for its modules
	// (novox/hq ADR 0112, to-be 27): a directory resource that states no path resolves to
	// <DataRoot>/<module>/<id>, and ${dir:<id>} names that place from the module's own files,
	// mounts and environment. A node setting fixed at installation; empty means the default,
	// /var/lib — see dir_into.go.
	DataRoot string

	// ReadsHealth says this machine's node-engine reads a resource's `health` (novox/hq ADR 0240 Phase B:
	// its statement's contract is link.ReadinessContract or later). An older engine parses strictly and
	// refuses a field it does not know, whole — so to it the field is not sent, and what it runs is
	// judged by liveness alone.
	ReadsHealth bool

	// JudgesRoot says this machine's node-engine judges a user's declared `root` (novox/hq ADR 0266: its
	// statement's contract is link.RootContract or later). To an older, strict engine the field is not
	// sent, and the account it names is not judged — which the self-check says, as not judged.
	JudgesRoot bool

	// ReadsBusy says this machine's node-engine reads a container's `busy` (novox/hq ADR 0335: its statement's
	// contract is link.BusyContract or later). To an older, strict engine the field is not sent, and the
	// container is replaced at once, as before.
	ReadsBusy bool

	// Hands says this machine's node-engine writes a filled file on the provisioner client's word alone (its
	// statement's contract is link.HandedContract or later, design 57 P7), and Provisioner is the account the
	// provisioner's client runs as here, empty where none runs (novox/hq ADR 0349 §4). With both, a moved module's
	// templated files are handed to the client (handed.go); without either, it composes as before.
	Hands       bool
	Provisioner string
	// Assigned is, by module, whether the vault judged it handed (AssignmentHands of the plan in its assignment), as the
	// vault answered the node composing itself; where it names a module, Handing follows it alone (issue 774). Nil, or a
	// module it does not name, is judged by the manifest and the machine, as the composer of the plans does.
	Assigned map[string]bool
}

// RootField is a user resource's field saying the account must never become root without a person
// (novox/hq ADR 0266).
const RootField = "root"

// Composed is a declaration's resources and which module each came from.
//
// Owner is kept beside the resources because a resource id cannot be split back into its module:
// a module's name may itself contain a dot. What the mesh adds of its own — an opening, the guard —
// has no owner.
//
// Received is what each module on the machine is given for each requirement it receives — the same
// contributions its received file is written from, kept beside it so the mesh can also issue them
// on the bus in the module's membership (novox/hq ADR 0167). By module, then requirement.
type Composed struct {
	Resources []map[string]any
	Owner     map[string]string
	Received  map[string]map[string][]Contribution
	// LeftOut is every module of this machine's set that was left out of its declaration, and
	// why (novox/hq ADR 0163, rule 6): a setting stored for it that its definition can no longer
	// compose. Its held things are kept and its containers untouched — the machine is told so —
	// and it is told everything else.
	LeftOut map[string]string
	// Foreseen is every own secret composed with ForeseenSealed in its place (Rendering.Foreseen),
	// as `module/name`, sorted: what the next send will make. Never set on a declaration that is
	// sent — a placeholder in a sealed file is a credential the process cannot read.
	Foreseen []string
	// Unplaced is every contribution the holder's template could not render into something, each
	// naming its module and why (novox/hq ADR 0255): that piece is left out and the machine is told
	// everything else. Push and plan say it; the merge gate refuses a change that adds one.
	Unplaced []string
	// HandedOnly is each file left out because only the provisioner's client fills it and the module is not handed on
	// this machine (a provider's consumers file, ADR 0373), said once in the plan. Not an unplaced contribution, which
	// the merge gate refuses: a module not handed composes as it did.
	HandedOnly []string
	// Filled is the path of every file handed to the provisioner, in the order composed: the declaration's
	// filled files (novox/hq ADR 0349 §4, §5). Plans is each handed module's plan on this machine, by module.
	// Both empty where nothing is handed, and the declaration is then what it was.
	Filled []string
	Plans  map[string]Plan
}

// ForeseenSealed is what stands for an own secret a send will make, in a composition asked ahead of
// the send. Not a sealed value: nothing composed with it may be sent.
const ForeseenSealed = "foreseen: made by the next send"

const BusMembershipPath = "/var/lib/mesh/membership-next.json"

// mapping reads a container's port mapping — `[address:]outer:inner[/protocol]`, the address
// possibly an IPv6 one in brackets — indexing from the end, so an address's own colons never
// shift the ports. Not ok for a short form or anything that is not a mapping.
func mapping(written string) (outer, inner int, address string, ok bool) {
	written = strings.TrimSpace(written)
	if cut := strings.LastIndex(written, "/"); cut >= 0 {
		written = written[:cut]
	}
	parts := strings.Split(written, ":")
	if len(parts) < 2 {
		return 0, 0, "", false
	}
	inner, err := strconv.Atoi(parts[len(parts)-1])
	if err != nil {
		return 0, 0, "", false
	}
	outer, err = strconv.Atoi(parts[len(parts)-2])
	if err != nil {
		return 0, 0, "", false
	}
	return outer, inner, strings.Join(parts[:len(parts)-2], ":"), true
}

// Contribution is one module telling the answer to a requirement what it needs from it.
type Contribution struct {
	// From is the module that said it, so the provider and a person reading the file can tell
	// which route belongs to what.
	From string `json:"from"`
	// Node is the machine it said it from, empty when that is this one.
	//
	// A provision answered from anywhere in the mesh has consumers on other machines, and the
	// provider has to know who they are — a database told to create a password and not who for
	// cannot do anything with it. Contributions were node-local until this, which meant the one
	// case that most needed them was the one they did not reach.
	Node string `json:"node,omitempty"`
	// At is where that machine is on the private network, empty when it is not on one or when it
	// is this machine.
	//
	// The mesh knows it and a provider should not have to derive it. A reverse proxy is told
	// *send traffic to this consumer* and has to open a connection — so without this every
	// provider that reaches back to a consumer would have to know how the mesh names machines,
	// which is a convention leaking into every module that implements a provision.
	At string `json:"at,omitempty"`
	// As is who this consumer is: what the provider should call the login it creates.
	//
	// **Said by the mesh rather than invented by the provisioner** (novox/hq 04-ISSUES/023). It
	// used to be neither — the provisioner made a name, and the consumer, which has to present it
	// to authenticate, had no way to learn it. One derivation reaches both ends, so they agree by
	// construction.
	// Omitted when there is none. A contribution that is not a credential grant — a module
	// offering something to another on its own machine — has nobody to be identified to, and a
	// field that is always present and usually empty teaches a reader to ignore it.
	As string `json:"as,omitempty"`
	// Secret is the file on this machine holding that consumer's credential, sealed to it.
	//
	// Named rather than carried, for the same reason the private network's key is: the mesh
	// discarded the value and could not put it here if it wanted to. What is here is where to
	// find it.
	Secret string `json:"secret,omitempty"`
	// Values are the module's own, with settings applied. What the keys mean is agreed by the
	// requirement's name — everything providing `reverse-proxy` understands the same shape, which
	// is what makes swapping one for another cost nothing.
	Values map[string]any `json:"values"`
	// Derived is what this provider's own definition said it derives for this consumer, already
	// derived (novox/hq ADR 0202).
	//
	// **The provider is told, rather than recomputing it.** A served value may name the consumer's
	// identity — a bucket named for who is asking, a database prefixed with it — and before this
	// the rule lived twice: once in the provisioner's code, once transcribed into every consumer's
	// definition. The mesh fills the provider's own statement here and delivers the same filled
	// value to the consumer, so the two cannot disagree: there is no second computation to
	// disagree with.
	//
	// Only the keys that are per-consumer. The rest of what the provider serves is the same for
	// everyone and is in its own definition, where it already is.
	Derived map[string]any `json:"derived,omitempty"`
}

// Kept is one secret as the operator can recover it: where it belongs, and the value sealed to the
// operator's key. Never a node's blob, and never a value.
//
// Two kinds, addressed the same way — by the node and module that hold it and the name they know
// it by. An `own` secret is one a module has for itself; a `pair` secret is a credential the
// module was granted for a provision it requires (`name` is the provision), and Provider says which
// node grants it.
type Kept struct {
	Node   string `json:"node"`
	Module string `json:"module"`
	Name   string `json:"name"`
	// Kind is `own` or `pair`.
	Kind string `json:"kind"`
	// Provider is the node granting a pair credential; empty for an own secret.
	Provider string `json:"provider,omitempty"`
	// Origin is `made` or `accepted` — whether the mesh minted it or a person supplied it.
	Origin string `json:"origin"`
	// Sealed is the value, sealed to the operator key named in Key.
	Sealed string    `json:"sealed"`
	Key    string    `json:"key"`
	MadeAt time.Time `json:"made-at"`
	// Local is the credential's name inside the consumer where it holds several (ADR 0094).
	Local string `json:"local,omitempty"`
}

// KeptExport is what a person keeps beside the operator key, and what a vault keeps on its disk:
// every operator-sealed copy, and the honest list of what has none.
type KeptExport struct {
	Export      int    `json:"export"`
	OperatorKey string `json:"operator-key"`
	Fingerprint string `json:"fingerprint"`
	// Kept is sealed to OperatorKey. EarlierKey is sealed to a key the mesh has since replaced —
	// recoverable with that key, if the person still has it, and with nothing else. Unrecoverable
	// has no operator copy at all.
	Kept          []Kept `json:"kept"`
	EarlierKey    []Kept `json:"sealed-to-earlier-key,omitempty"`
	Unrecoverable []Kept `json:"unrecoverable,omitempty"`
}

// sortedKeys is map iteration made repeatable, which everything written to a machine needs.
func sortedKeys[V any](m map[string]V) []string {
	out := make([]string, 0, len(m))
	for k := range m {
		out = append(out, k)
	}
	sort.Strings(out)
	return out
}

func asPort(v any) (int, bool) {
	switch n := v.(type) {
	case int:
		return n, true
	case float64:
		return int(n), true
	}
	return 0, false
}

// PreparationArgument is how the mesh asks a module to prepare its state: one word, to the module's
// own program, whatever that program is (novox/hq ADR 0135).
//
// **One word for every kind of module.** A module built as a Go binary receives it as its argument;
// one built as a bundle receives it through the runtime, whose entry takes the same word. So the
// mesh has one way of asking and a module has one way of answering, and neither learns the other's
// shape.
const PreparationArgument = "prepare"

// endpointPorts is a module's endpoint names against the ports they listen on.
func endpointPorts(m Manifest) map[string]int {
	out := map[string]int{}
	for _, l := range m.Listens {
		if name := strings.TrimSpace(l.Name); name != "" {
			out[name] = l.Port
		}
	}
	return out
}