package main

// Who can become root here without a person (novox/hq ADR 0259 §8): the controller's self-check may ask it for
// the accounts agents run as and the account the machine's runtime runs commands as.
//
// **Conservative, as the review of 2026-10-09 asked.** An account can become root without a person when:
//   - it is root;
//   - it is a member of a group that is root by another name (docker, disk, root, lxd, incus-admin, libvirt);
//   - **sudo lists any rule for it at all** — with NOPASSWD or without, for every command or for one. A named
//     command is root when it can start a shell or write a file (systemctl, tee, bash, pacman, an editor, …),
//     and no list of safe commands is kept: none is proven safe here. A rule that asks a password is root too,
//     because sudo keeps a password typed by the person for minutes, during which a program of the same
//     account needs none. This is the node-engine's own rule for an agent account (ADR 0266: "any sudo rule").
//
// **What cannot be judged is an error, never a no**: an account this machine does not know, sudo that could not
// be asked, a listing that cannot be read. The caller says it was not measured.
//
// **Measured as the runtime's account**, which these tools run as: an agent that could act as that account
// could change this answer, so the controller takes the agent account's verdict from the node-engine, which
// runs as root (ADR 0266), and this tool is a reading for a person, not that verdict.

import (
	"fmt"
	"regexp"
	"strings"
)

// Escalation is one account's answer.
type Escalation struct {
	Account string `json:"account"`
	Root    bool   `json:"root_without_a_person"`
	Why     string `json:"why"`
}

// rootGroups are groups that are root by another name.
var rootGroups = map[string]string{"docker": "the docker group, which can mount the machine's root file system",
	"disk": "the disk group, which reads and writes the drives raw", "root": "the root group",
	"lxd": "the lxd group, which runs privileged containers", "incus-admin": "the incus-admin group, which runs privileged containers",
	"libvirt": "the libvirt group, which runs machines with the host's disks"}

var accountShape = regexp.MustCompile(`^[a-z_][a-z0-9_-]{0,31}$`)

// Escalations answers, for each account, whether it can become root here without a person. An account that
// cannot be judged fails the whole answer: never a no.
func (m *Machine) Escalations(accounts []string) ([]Escalation, error) {
	if len(accounts) == 0 {
		return nil, fmt.Errorf("name the accounts to judge")
	}
	var out []Escalation
	for _, a := range accounts {
		if !accountShape.MatchString(a) {
			return nil, fmt.Errorf("%q is not an account name", a)
		}
		e, err := m.escalation(a)
		if err != nil {
			return nil, fmt.Errorf("%s cannot be judged, so nothing is said of it: %v", a, err)
		}
		out = append(out, e)
	}
	return out, nil
}

func (m *Machine) escalation(account string) (Escalation, error) {
	e := Escalation{Account: account}
	if account == "root" {
		e.Root, e.Why = true, "it is root"
		return e, nil
	}
	id := m.Run(bg(), "id", "-nG", account)
	if id.Status != 0 || id.Err != "" {
		return e, fmt.Errorf("this machine does not know the account: %s", strings.TrimSpace(firstLine(id.Stderr+id.Err)))
	}
	for _, g := range strings.Fields(id.Stdout) {
		if why, ok := rootGroups[g]; ok {
			e.Root, e.Why = true, "a member of "+why
			return e, nil
		}
	}
	// sudo's own word, for that account: listing another account's rules needs root, which the runtime's
	// account escalates to as the mesh's acting tools do.
	r := m.Run(bg(), "sudo", "-n", "-l", "-U", account)
	listing := r.Stdout + r.Stderr
	if strings.Contains(listing, "is not allowed to run sudo") {
		e.Why = "no sudo rule names it, and no group it is in is root by another name"
		return e, nil
	}
	if r.Status != 0 || r.Err != "" {
		return e, fmt.Errorf("sudo could not be asked: %s", strings.TrimSpace(firstLine(r.Stderr+r.Err)))
	}
	rules := ParseList(r.Stdout, account)
	if !mayRun.MatchString(firstMayRun(r.Stdout)) {
		return e, fmt.Errorf("sudo's listing could not be read")
	}
	if len(rules.Rules) == 0 {
		e.Why = "sudo lists no rule for it, and no group it is in is root by another name"
		return e, nil
	}
	var lines []string
	for _, rule := range rules.Rules {
		lines = append(lines, rule.Line)
	}
	how := "a password the person typed is kept by sudo for minutes"
	for _, rule := range rules.Rules {
		if hasTag(rule.Tags, "NOPASSWD") {
			how = "with no password"
			break
		}
	}
	e.Root, e.Why = true, "sudo has a rule for it ("+strings.Join(lines, "; ")+"), "+how+
		": any rule counts, since no command is proven unable to reach root"
	return e, nil
}

// firstMayRun is the listing's "User … may run the following commands on …:" line, or "".
func firstMayRun(out string) string {
	for _, l := range strings.Split(out, "\n") {
		if l = strings.TrimSpace(l); mayRun.MatchString(l) {
			return l
		}
	}
	return ""
}