#!/usr/bin/env bash
# {{PROJECT_NAME}} — agent name generator.
#
# Usage:
#   scripts/agent-name.sh            Print a unique agent name (agent-<adjective>-<noun>-<NN>).
#   scripts/agent-name.sh --short    Same, without the leading "agent-" (for worktree names).
#
# Why a generator instead of "pick a distinctive name": the atomic bead claim
# (`bd update <id> --claim`) is a compare-and-set KEYED ON THE ACTOR, and
# same-actor claims are idempotent — two agents that converge on the same name
# get ZERO collision protection. Agents asked to invent names converge (they
# sample the same distribution), so unique names need real entropy plus a
# collision check. The name doubles as the human-readable ownership label in
# `bd list`, the reaper report, branch names, and git blame.
#
# Collision sources checked (all best-effort; a missing tool never blocks):
#   - assignees of in-progress beads (`bd list --status in_progress --json`)
#   - actors persisted in .worktrees/*/.agent-env (cwd and the git toplevel)
#   - local agent/* branches (the <name> segment maps to actor agent-<name>)
#
# Read-only: never mutates the repo, the tracker, or the filesystem.

set -euo pipefail

log() { printf "agent-name: %s\n" "$*" >&2; }

ADJECTIVES=(
  bouncy breezy chunky crispy dapper dizzy feisty fuzzy goofy grumpy
  jazzy jolly lanky mellow mighty nifty nimble peppy perky plucky
  quirky rowdy sassy shiny sleepy snazzy soggy sparkly spiffy spunky
  sturdy swanky toasty turbo wiggly witty wobbly zany zesty zippy
)
NOUNS=(
  badger banjo biscuit burrito cactus donut ferret gecko gizmo hammock
  kazoo llama mango marmot meerkat mongoose muffin nacho narwhal noodle
  otter pancake panda pelican pickle pretzel pudding quokka raccoon taco
  toucan tuba turnip ukulele waffle walrus wombat yeti zebra zucchini
)

# Entropy: 2 fresh bytes per draw from /dev/urandom. AGENT_NAME_ENTROPY_FILE
# is a TEST-ONLY hook substituting a fixed byte file (each draw reads from its
# start, so a constant file yields deterministic picks). An unreadable source
# falls back to $RANDOM — the generator must always produce a name.
ENTROPY_SRC="${AGENT_NAME_ENTROPY_FILE:-/dev/urandom}"

rand_index() {
  local mod="$1" raw=""
  raw="$(dd if="$ENTROPY_SRC" bs=2 count=1 2>/dev/null | od -An -tu2 | tr -d '[:space:]')" || raw=""
  [[ -n "$raw" ]] || raw=$((RANDOM * 32768 + RANDOM))
  printf '%d' $((raw % mod))
}

# Gather every taken name (one per line) from the best-effort sources.
taken_names() {
  # In-progress bead assignees.
  if command -v bd >/dev/null 2>&1 && command -v jq >/dev/null 2>&1; then
    bd list --status in_progress --json 2>/dev/null \
      | jq -r '.[]? | .assignee // empty' 2>/dev/null || true
  fi
  # Worktree-persisted actors: scan the cwd, the current toplevel, AND the
  # PRIMARY checkout root — from inside a worktree, --show-toplevel is the
  # worktree itself, and sibling worktrees' .agent-env files live under the
  # primary root's .worktrees/ (derived via --git-common-dir).
  local root common primary=""
  common="$(git rev-parse --git-common-dir 2>/dev/null || true)"
  if [[ -n "$common" ]]; then
    primary="$(cd "$common/.." 2>/dev/null && pwd || true)"
  fi
  for root in "." "$(git rev-parse --show-toplevel 2>/dev/null || true)" "$primary"; do
    [[ -n "$root" ]] || continue
    local env_file
    for env_file in "$root"/.worktrees/*/.agent-env; do
      [[ -f "$env_file" ]] || continue
      # setup-agent-worktree persists the sourceable `export BEADS_ACTOR=...`
      # form, so the pattern accepts an optional `export `. tr strips optional
      # quoting (BEADS_ACTOR="agent-x") — the actor grammar itself never
      # contains quotes, so this is lossless.
      sed -n -E 's/^(export[[:space:]]+)?BEADS_ACTOR=//p' "$env_file" | tr -d "'\""
    done
  done
  # Local AND remote-tracking agent/* branches: agent/<name>[/<bead-id>] →
  # actor agent-<name>. Remote refs cover concurrent agents on other machines
  # whose branches were fetched but never checked out here.
  git for-each-ref --format='%(refname)' 'refs/heads/agent/*' 'refs/remotes/*/agent/*' 2>/dev/null \
    | sed -n -E 's#.*/agent/([^/]+).*#agent-\1#p' || true
}

main() {
  local short=0
  case "${1:-}" in
    --short) short=1 ;;
    "") ;;
    *) printf 'usage: %s [--short]\n' "$0" >&2; exit 1 ;;
  esac

  local taken candidate adj noun attempt s found=0
  taken="$(taken_names)"

  # Every name carries a two-digit suffix from the START: the 40x40 wordlists
  # alone are ~1,600 names, and a fleet of agents starting CONCURRENTLY has a
  # real birthday-collision chance before any claim is visible to the collision
  # check below. The suffix widens the space to ~160,000, shrinking that
  # blind-window risk two orders of magnitude; the check then covers everything
  # already persisted.
  for ((attempt = 0; attempt < 10; attempt++)); do
    adj="${ADJECTIVES[$(rand_index "${#ADJECTIVES[@]}")]}"
    noun="${NOUNS[$(rand_index "${#NOUNS[@]}")]}"
    candidate="agent-$adj-$noun-$(printf '%02d' "$(rand_index 100)")"
    if ! grep -qxF "$candidate" <<<"$taken"; then
      found=1
      break
    fi
  done
  if [[ "$found" -ne 1 ]]; then
    # Ten straight collisions means degenerate entropy or a crowded namespace:
    # walk every suffix of the last word pair deterministically, CHECKING each.
    for ((s = 0; s < 100; s++)); do
      candidate="agent-$adj-$noun-$(printf '%02d' "$s")"
      if ! grep -qxF "$candidate" <<<"$taken"; then
        found=1
        break
      fi
    done
  fi
  if [[ "$found" -ne 1 ]]; then
    # FAIL CLOSED — this generator exists to guarantee actor uniqueness, so a
    # known-taken name must never be emitted. (Reaching this needs 110 straight
    # collisions across a 160k namespace: a stuck entropy source or a pathological
    # taken-list. Either way the operator must intervene.)
    log "ERROR: could not find an unused name (entropy source stuck, or namespace exhausted) — refusing to emit a colliding actor name"
    exit 1
  fi

  if [[ "$short" -eq 1 ]]; then
    printf '%s\n' "${candidate#agent-}"
  else
    printf '%s\n' "$candidate"
  fi
}

main "$@"