#!/usr/bin/env bash
set -euo pipefail

usage() {
  cat <<'EOF'
Usage:
  tmux-notify-run SESSION [--title TITLE] [--log PATH] [--cwd DIR] -- COMMAND [ARG...]
  tmux-notify-run --status [SESSION]

Starts COMMAND in a detached tmux session and sends a Windows notification when
it exits. Runtime state is stored under ~/.local/state/tmux-notify-run/SESSION/.

--status reports unfinished jobs: "running" if the tmux session or the runner PID
is still alive, "orphaned" if neither is (the runner died before recording an exit
code). Orphaned jobs are recorded as such so the status stops claiming "running".
EOF
}

die() {
  printf 'tmux-notify-run: %s\n' "$*" >&2
  exit 2
}

state_root=${XDG_STATE_HOME:-$HOME/.local/state}/tmux-notify-run

meta_field() {
  local file=$1 key=$2
  [[ -f $file ]] || return 0
  sed -n "s/^${key}=//p" "$file" | head -n 1
}

# Prints running | orphaned | unknown | exit=N for one job directory.
job_state() {
  local dir=$1 state pid
  [[ -f $dir/status ]] || { printf 'unknown\n'; return 0; }
  state=$(<"$dir/status")
  [[ -n $state ]] || { printf 'unknown\n'; return 0; }
  if [[ $state == orphaned ]]; then
    printf 'orphaned\n'
    return 0
  fi
  if [[ $state != running ]]; then
    printf 'exit=%s\n' "$state"
    return 0
  fi
  local session_name
  session_name=$(meta_field "$dir/meta" session)
  if [[ -n $session_name ]] && tmux has-session -t "=$session_name" 2>/dev/null; then
    printf 'running\n'
    return 0
  fi
  pid=$(meta_field "$dir/meta" pid)
  # No PID recorded yet: the runner may be mid-startup, so make no claim.
  [[ -n $pid ]] || { printf 'unknown\n'; return 0; }
  if kill -0 "$pid" 2>/dev/null; then
    printf 'running\n'
  else
    printf 'orphaned\n' >"$dir/status"
    printf 'orphaned\n'
  fi
}

show_status() {
  local filter=${1:-} dir name state started hidden=0 shown=0
  [[ -d $state_root ]] || die "no jobs recorded under $state_root"
  for dir in "$state_root"/*/; do
    [[ -d $dir ]] || continue
    name=${dir%/}
    name=${name##*/}
    if [[ -n $filter && $name != "$filter" ]]; then
      continue
    fi
    state=$(job_state "${dir%/}")
    if [[ -z $filter && $state == exit=* ]]; then
      hidden=$((hidden + 1))
      continue
    fi
    started=$(meta_field "$dir/meta" started_at)
    printf '%-10s %-25s %s\n' "$state" "${started:-unknown}" "$name"
    shown=$((shown + 1))
  done
  if [[ -n $filter ]]; then
    [[ $shown -gt 0 ]] || die "no such job: $filter"
  else
    printf '%d unfinished, %d finished job(s) not shown\n' "$shown" "$hidden"
  fi
}

[[ $# -gt 0 ]] || { usage >&2; exit 2; }
if [[ $1 == -h || $1 == --help ]]; then
  usage
  exit 0
fi
if [[ $1 == --status ]]; then
  command -v tmux >/dev/null || die "tmux is not installed"
  show_status "${2:-}"
  exit 0
fi

session=$1
shift
[[ $session =~ ^[A-Za-z0-9_.-]+$ ]] || die "SESSION may contain only letters, numbers, dot, underscore, and hyphen"

title="tmux: $session"
cwd=$PWD
log=""

while [[ $# -gt 0 ]]; do
  case $1 in
    --title)
      [[ $# -ge 2 ]] || die "--title requires a value"
      title=$2
      shift 2
      ;;
    --log)
      [[ $# -ge 2 ]] || die "--log requires a value"
      log=$2
      shift 2
      ;;
    --cwd)
      [[ $# -ge 2 ]] || die "--cwd requires a value"
      cwd=$2
      shift 2
      ;;
    --)
      shift
      break
      ;;
    -h|--help)
      usage
      exit 0
      ;;
    *)
      die "unknown option: $1"
      ;;
  esac
done

[[ $# -gt 0 ]] || die "missing COMMAND after --"
command -v tmux >/dev/null || die "tmux is not installed"
command -v setsid >/dev/null || die "setsid is not installed"
[[ -d $cwd ]] || die "working directory does not exist: $cwd"
tmux has-session -t "=$session" 2>/dev/null && die "tmux session already exists: $session"

job_dir=$state_root/$session
mkdir -p "$job_dir"

if [[ -z $log ]]; then
  log=$job_dir/job.log
elif [[ $log != /* ]]; then
  log=$PWD/$log
fi
mkdir -p "$(dirname "$log")"

runner=$job_dir/run.sh
status_file=$job_dir/status
meta_file=$job_dir/meta
notify=${TMUX_NOTIFY_COMMAND:-$HOME/bin/claude-notify}

tmux_env=()
env_names=()
while IFS= read -r -d '' entry; do
  name=${entry%%=*}
  case $name in
    TMUX|TMUX_PANE|SHLVL|_)
      continue
      ;;
  esac
  tmux_env+=("$entry")
  env_names+=("$name")
done < <(env -0)

{
  printf '#!/usr/bin/env bash\n'
  printf 'set -uo pipefail\n'
  printf 'cwd=%q\n' "$cwd"
  printf 'log=%q\n' "$log"
  printf 'status_file=%q\n' "$status_file"
  printf 'meta_file=%q\n' "$meta_file"
  printf 'notify=%q\n' "$notify"
  printf 'title=%q\n' "$title"
  printf 'session=%q\n' "$session"
  printf 'command=('
  printf ' %q' "$@"
  printf ' )\n'
  printf 'env_names=('
  printf ' %q' "${env_names[@]}"
  printf ' )\n'
  cat <<'EOF'
cd "$cwd" || exit 125
: >"$log"
printf 'running\n' >"$status_file"
{
  printf 'session=%s\n' "$session"
  printf 'pid=%s\n' "$$"
  printf 'started_at=%s\n' "$(date --iso-8601=seconds)"
  printf 'cwd=%s\n' "$cwd"
  printf 'log=%s\n' "$log"
} >"$meta_file"

declare -A allowed_env=()
for name in "${env_names[@]}"; do
  allowed_env["$name"]=1
done
job_env=()
while IFS= read -r -d '' entry; do
  name=${entry%%=*}
  if [[ ${allowed_env[$name]+present} ]]; then
    job_env+=("$entry")
  fi
done < <(env -0)

# A pipeline (not a process substitution) waits for tee, so the log is complete
# before the status file says the job finished.
env -i "${job_env[@]}" "${command[@]}" 2>&1 | tee -a "$log"
rc=${PIPESTATUS[0]}

printf '%s\n' "$rc" >"$status_file"
{
  printf 'finished_at=%s\n' "$(date --iso-8601=seconds)"
  printf 'exit_code=%s\n' "$rc"
} >>"$meta_file"

if [[ $rc -eq 0 ]]; then
  message="Completed successfully"
else
  message="Failed with exit code $rc"
fi

if [[ -x $notify ]]; then
  setsid -f "$notify" "$title" "$message" --force </dev/null >/dev/null 2>&1
fi

exit "$rc"
EOF
} >"$runner"
chmod 700 "$runner"

tmux_args=(new-session -d -s "$session")
for entry in "${tmux_env[@]}"; do
  tmux_args+=(-e "$entry")
done

tmux "${tmux_args[@]}" "$runner"

printf 'Started tmux session: %s\n' "$session"
printf 'Log: %s\n' "$log"
printf 'Status: %s\n' "$status_file"
printf 'Attach: tmux attach -t %s\n' "$session"