// Package process is a module's own process's connection to the bus (novox/hq ADR 0436 clause 4): it reads
// the account the controller delivers, connects as it with its pinned fingerprint and its inbox prefix, and
// offers emitting an event, the module's states with compare-and-set, consuming a work queue, reading the
// router's records of the module's own asks, and calling a tool or verb — each only as the account's grants
// allow. It offers no Serve and no way to serve a tool: a process never answers a call. A sibling of stdio,
// which it imports only for stdio's pure types (ErrChanged, CodeChanged, StateEntry, EmitOptions); it never
// touches stdio's current, channel or live(), which stay the bundle's own way to the bus.
package process

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

// Account is a process's own bus account, exactly as the controller delivers it as the module's own secret
// broker-<process id> (mesh-controller cmd/mesh-controller/modules.go issueProcess, heldProcessAccount, and
// issueWith for a module's own broker account, which also carries claims). A process account carries no
// claims at all; this type reads either file without error.
type Account struct {
	URL         string `json:"url"`
	Fingerprint string `json:"fingerprint,omitempty"`
	Node        string `json:"node"`
	Module      string `json:"module"`
	User        string `json:"user"`
	Password    string `json:"password"`
	// Claims rides on a module's own broker account only; a process holds no seat, so its own account
	// carries none (novox/hq ADR 0436 §2, §3). Kept raw: this package never reads it.
	Claims json.RawMessage `json:"claims,omitempty"`
}

// InboxPrefix is this account's own inbox, and nothing wider: `_INBOX.<user>`.
func (a Account) InboxPrefix() string { return "_INBOX." + a.User }

// ReadAccount reads and validates the account file the controller delivers: it refuses a file missing url,
// user or password, naming the field — never the password, which does not appear in an error.
func ReadAccount(path string) (Account, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return Account{}, fmt.Errorf("reading the process account at %s: %w", path, err)
	}
	var a Account
	if err := json.Unmarshal(data, &a); err != nil {
		return Account{}, fmt.Errorf("the process account at %s is not JSON: %w", path, err)
	}
	for _, f := range []struct{ name, value string }{
		{"url", a.URL}, {"user", a.User}, {"password", a.Password},
	} {
		if f.value == "" {
			return Account{}, fmt.Errorf("the process account at %s has no %s", path, f.name)
		}
	}
	return a, nil
}