package catalogue

import (
	"bytes"
	"encoding/json"
	"fmt"
)

// ProcessBusField is the key a process resource declares its bus on. Controller-side only: never composed
// onto the node-engine's process resource (novox/hq ADR 0436 §1) — the wire declaration is mesh-host's own,
// vendored, with a strict decoder that refuses an unknown key.
const ProcessBusField = "bus"

// ProcessBus is what one process of a module does on the bus (novox/hq ADR 0436 §1, §2, §3, §5): its own bus
// account, granted exactly this and nothing of the module's other grants or the tool runner's — never a seat
// to hold or serve, never a tool call or seat verb answered, never a restricted stream heard, never a
// warrant published (§3, §5).
type ProcessBus struct {
	// Emits are the events this process emits, named locally, as the module's own Emits names them
	// (EmitsAll): a process emits only what its module may emit as a whole.
	Emits []string `json:"emits,omitempty"`
	// Queues are the module's own work-queue streams (ADR 0436 §6) this process consumes.
	Queues []string `json:"queues,omitempty"`
	// State is the module's own state, by local name, this process reads and writes.
	State []string `json:"state,omitempty"`
	// Asks says whether this process reads the router's records of this module's own asks.
	Asks bool `json:"asks,omitempty"`
	// Invokes are the tools and seat verbs this process calls, each <module>.<tool> or a role's
	// seat:<seat>.<verb> (as Manifest.Invokes), or * for every tool on the mesh.
	Invokes []string `json:"invokes,omitempty"`
	// Removes are what a tools bundle's account may remove from the bus, from a closed set (BusRemovals; novox/hq ADR
	// 0564 Limits 4): declared alone, by the module holding mesh-broker, never by a process.
	Removes []string `json:"removes,omitempty"`
}

// What a bus account may remove (novox/hq ADR 0564 Limits 4), each its own grant: the controller's consumer on
// DEAD_LETTER_NOTICES (the lease write's step, clause 5), and keys of the node-engine's acts bucket. A further consumer
// or bucket is a change of this set, through a decision.
const (
	RemovesControllerDeadLetterConsumer = "DEAD_LETTER_NOTICES.controller"
	RemovesEngineActs                   = "mesh-host_acts"
	// RemovesAssignmentsStream is the stream ASSIGNMENTS, removed whole at the lease write (novox/hq research 072 row 33):
	// its 350 messages have no consumer, and the placement is the provisioner's from then on.
	RemovesAssignmentsStream = "ASSIGNMENTS"
)

// BusAccount is one account of a module's own beside its `broker`: a process's (ADR 0436) or a tools bundle's (ADR 0564
// Limits 4), by its id (the process resource's, or the bundle's binary), with what its bus says.
type BusAccount struct {
	ID  string
	Bus ProcessBus
	// Tools says it is a tools bundle's, run by the node's tool runtime, not a process the node runs.
	Tools bool
}

// BusAccounts is every own bus account of the module, processes first in resource order, then tools bundles in artifact
// order: what the grant composition composes a principal for, each delivered in its own secret broker-<id>. A tools
// bundle's is read from the repository's build, or from the resolved manifest's bundles.
func (m Manifest) BusAccounts() []BusAccount {
	var out []BusAccount
	buses := m.ProcessBuses()
	for _, r := range m.Resources {
		id := fmt.Sprint(r["id"])
		if b, ok := buses[id]; ok && fmt.Sprint(r["type"]) == "process" {
			out = append(out, BusAccount{ID: id, Bus: b})
		}
	}
	seen := map[string]bool{}
	if m.Build != nil {
		for _, a := range m.Build.Artifacts {
			if a.Bus != nil && a.Kind == ArtifactBundle && BinaryOf(a) != "" && !seen[BinaryOf(a)] {
				seen[BinaryOf(a)] = true
				out = append(out, BusAccount{ID: BinaryOf(a), Bus: *a.Bus, Tools: true})
			}
		}
	}
	for _, b := range m.Bundles {
		if b.Bus != nil && b.Binary != "" && !seen[b.Binary] {
			seen[b.Binary] = true
			out = append(out, BusAccount{ID: b.Binary, Bus: *b.Bus, Tools: true})
		}
	}
	return out
}

// ToolsBusSecret says name is the own secret a tools bundle's bus account is held in: `broker-<binary>` for a bundle
// whose bus the manifest declares (ADR 0564 Limits 4). Its file belongs to the runtime's account, which runs the bundle.
func ToolsBusSecret(m Manifest, name string) bool {
	for _, a := range m.BusAccounts() {
		if a.Tools && name == "broker-"+a.ID {
			return true
		}
	}
	return false
}

// UnmarshalJSON reads a process's bus strictly: an unknown key — serves, a seat to hold or claim, or
// anything else that would answer a tool call or a seat's verb — is refused here, by name (novox/hq ADR
// 0436 §3).
func (b *ProcessBus) UnmarshalJSON(raw []byte) error {
	type plain ProcessBus
	var p plain
	dec := json.NewDecoder(bytes.NewReader(raw))
	dec.DisallowUnknownFields()
	if err := dec.Decode(&p); err != nil {
		return fmt.Errorf("a process's bus is {emits, queues, state, asks, invokes}: %w", typedUnknown(err))
	}
	*b = ProcessBus(p)
	return nil
}

// processBusOf is the bus a process resource declares, and whether it declared one at all.
func processBusOf(r map[string]any) (bus ProcessBus, present bool, err error) {
	raw, present := r["bus"]
	if !present {
		return ProcessBus{}, false, nil
	}
	body, err := json.Marshal(raw)
	if err != nil {
		return ProcessBus{}, true, err
	}
	if err := json.Unmarshal(body, &bus); err != nil {
		return ProcessBus{}, true, err
	}
	return bus, true, nil
}

// ProcessBuses is every process of this module that declares bus, by its id (the manifest's own resource
// id, novox/hq ADR 0436, settled by the lead) — what the grant composition reads to grant a process
// account exactly what it emits, consumes and calls (novox/hq ADR 0436 §2).
func (m Manifest) ProcessBuses() map[string]ProcessBus {
	var out map[string]ProcessBus
	for _, r := range m.Resources {
		if fmt.Sprint(r["type"]) != "process" {
			continue
		}
		b, present, err := processBusOf(r)
		if !present || err != nil {
			continue
		}
		if out == nil {
			out = map[string]ProcessBus{}
		}
		out[fmt.Sprint(r["id"])] = b
	}
	return out
}