#!/bin/bash
# bus.sh - client for the JYM message bus. macOS, Linux and Git Bash on Windows.
# Subcommands:
#   bus.sh health            liveness + expiry date
#   bus.sh send "text"       send to the other party ("-" reads stdin)
#   bus.sh poll              print messages newer than the saved cursor, advance cursor
#   bus.sh wait [seconds]    poll every 15s until a message arrives (default 90s cap,
#                            sized under Claude Code's 120s Bash timeout)
# The secret is read from a 600 file, never from an argument, so it cannot land in
# shell history or a process listing.
set -euo pipefail

CFG="$HOME/.config/jym-bus"
die() { echo "bus: $*" >&2; exit 1; }

[ -d "$CFG" ] || die "no config dir $CFG"
URL=$(cat "$CFG/url" 2>/dev/null) || die "missing $CFG/url"
ME=$(cat "$CFG/me" 2>/dev/null) || die "missing $CFG/me (must contain a or b)"
[ -f "$CFG/secret" ] || die "missing $CFG/secret"

# Permission check. BSD stat (macOS) and GNU stat (Linux, Git Bash) take different
# flags, so try one then the other. Git Bash on Windows reports a mode that does not
# mean much because NTFS uses ACLs, so a warning there is not a hard failure.
if PERM=$(stat -f "%Lp" "$CFG/secret" 2>/dev/null); then :
elif PERM=$(stat -c "%a" "$CFG/secret" 2>/dev/null); then :
else PERM="unknown"; fi
case "$(uname -s)" in
  MINGW*|MSYS*|CYGWIN*)
    [ "$PERM" = "600" ] || echo "bus: warning - cannot enforce file mode on Windows (saw $PERM). Confirm the ACL." >&2 ;;
  *)
    [ "$PERM" = "600" ] || die "$CFG/secret must be chmod 600 (it is $PERM); refusing to run" ;;
esac

SECRET=$(cat "$CFG/secret")
case "$ME" in
  a) THEM=b ;;
  b) THEM=a ;;
  *) die "me must be a or b, got '$ME'" ;;
esac
CURSOR_FILE="$CFG/cursor"

cursor() { cat "$CURSOR_FILE" 2>/dev/null || echo 0; }

# call <curl args...> - runs curl with auth, prints the body on 200, and turns the
# bus's designed failure codes into plain-language errors instead of raw curl output.
call() {
  local out status body
  out=$(curl -sS --max-time 30 -w $'\n%{http_code}' \
        -H "Authorization: Bearer $SECRET" "$@") \
    || die "network error reaching $URL (offline, DNS, or the project was deleted)"
  status=${out##*$'\n'}
  body=${out%$'\n'*}
  case "$status" in
    200) printf '%s\n' "$body" ;;
    401) die "secret rejected (401). It has been rotated. Get the current secret from JY and update $CFG/secret. Do not retry with this one." ;;
    410) die "the bus has expired (410) and is dead by design. Nothing to retry. Stop the loop." ;;
    429) die "rate limited (429). Wait a minute before the next call." ;;
    *)   die "unexpected HTTP $status: $body" ;;
  esac
}

cmd=${1:-}
[ -n "$cmd" ] && shift

case "$cmd" in
  health)
    call "$URL/health"
    ;;

  send)
    [ $# -ge 1 ] || die 'usage: bus.sh send "message text"   (or: bus.sh send - to read stdin)'
    if [ "$1" = "-" ]; then TEXT=$(cat); else TEXT="$1"; fi
    [ -n "$TEXT" ] || die "refusing to send an empty message"
    PAYLOAD=$(printf '%s' "$TEXT" | python3 -c \
      'import json,sys; print(json.dumps({"to":sys.argv[1],"from":sys.argv[2],"body":sys.stdin.read()}))' \
      "$THEM" "$ME")
    call -X POST "$URL/msg" -H "content-type: application/json" --data-binary "$PAYLOAD"
    ;;

  poll)
    RESP=$(call "$URL/msg?for=$ME&since=$(cursor)")
    BUS_RESP="$RESP" BUS_CURSOR_FILE="$CURSOR_FILE" python3 <<'PY'
import json, os, datetime
msgs = json.loads(os.environ["BUS_RESP"])
if not msgs:
    print("no new messages")
else:
    for m in msgs:
        t = datetime.datetime.fromtimestamp(m["ts"] / 1000).strftime("%Y-%m-%d %H:%M:%S")
        print(f'--- msg {m["id"]} from {m["sender"]} at {t} ---')
        print(m["body"])
    # Cursor advances only after the messages were printed. If this write is ever
    # lost the same messages replay on the next poll - the reader must tolerate
    # seeing a message twice, never miss one.
    with open(os.environ["BUS_CURSOR_FILE"], "w") as f:
        f.write(str(msgs[-1]["id"]))
PY
    ;;

  wait)
    SECS=${1:-90}
    END=$(( $(date +%s) + SECS ))
    while :; do
      OUT=$("$0" poll)
      if [ "$OUT" != "no new messages" ]; then
        printf '%s\n' "$OUT"
        exit 0
      fi
      if [ "$(date +%s)" -ge "$END" ]; then
        echo "no new messages after ${SECS}s"
        exit 0
      fi
      sleep 15
    done
    ;;

  *)
    die "usage: bus.sh health | send \"text\" | send - | poll | wait [seconds]"
    ;;
esac