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

# tmux-open — open a new tmux window (or session) and run a command
# Usage: tmux-open [-k|--keep] [-h|--help] <window-name> <start-dir> <cmd> [args...]

usage() {
    cat <<'EOF'
Usage: tmux-open [-k|--keep] [-h|--help] <window-name> <start-dir> <cmd> [args...]

Open a new tmux window in the current session and run a command.
If not inside tmux, create a new session named after the window and attach.

Positional arguments:
  window-name   Name for the new tmux window (and session, if creating one)
  start-dir     Working directory for the new window
  cmd [args...] Command to run (variadic)

Options:
  -k, --keep    After the command exits, keep the pane visible (remain-on-exit)
                so you can inspect output. Default: pane closes when command exits.
  -h, --help    Show this help message

If `mise` is on PATH, the command runs under `mise x`.

Errors:
  - tmux not installed
  - fewer than 3 positional args
  - start-dir does not exist
  - a window with the same name already exists in the current session
EOF
}

# --- Flag parsing ---
keep_shell=0
while (( $# > 0 )); do
    case "$1" in
        -k|--keep)  keep_shell=1; shift ;;
        -h|--help)  usage; exit 0 ;;
        --)         shift; break ;;
        -*)         echo "error: unknown option: $1" >&2; usage >&2; exit 1 ;;
        *)          break ;;
    esac
done

# --- Positional arg validation ---
if (( $# < 3 )); then
    echo "error: expected at least 3 positional arguments (window-name, start-dir, cmd)" >&2
    usage >&2
    exit 1
fi

window_name="$1"; shift
start_dir="$1"; shift
cmd_args=("$@")

# --- Pre-flight checks ---
if ! command -v tmux >/dev/null 2>&1; then
    echo "error: tmux is not installed or not on PATH" >&2
    exit 1
fi

if [[ ! -d "$start_dir" ]]; then
    echo "error: directory does not exist: $start_dir" >&2
    exit 1
fi

if (( ${#cmd_args[@]} == 0 )); then
    echo "error: no command specified" >&2
    exit 1
fi

# Duplicate window name check (only relevant inside tmux)
if [[ -n "${TMUX:-}" ]]; then
    if tmux list-windows -F '#{window_name}' | grep -Fxq "$window_name"; then
        echo "error: a window named '$window_name' already exists in the current session" >&2
        exit 1
    fi
fi

# --- Detect mise ---
has_mise=0
if command -v mise >/dev/null 2>&1; then
    has_mise=1
fi

# --- Build the command for the new window ---
# We need to construct a single shell command string for tmux.
# The command runs; pane closes on exit (or stays visible with --keep via remain-on-exit).

# Build the inner command based on mode and mise availability
# For argv mode, quote each argument
quoted_args=()
for arg in "${cmd_args[@]}"; do
    quoted_args+=("$(printf '%q' "$arg")")
done
if (( has_mise )); then
    inner_cmd="mise x -- ${quoted_args[*]}"
else
    inner_cmd="${quoted_args[*]}"
fi

# --- Create window or session ---
if [[ -n "${TMUX:-}" ]]; then
    tmux new-window -n "$window_name" -c "$start_dir" "$inner_cmd"
    if (( keep_shell )); then
        tmux set-option remain-on-exit on
    fi
else
    tmux new-session -d -n "$window_name" -s "$window_name" -c "$start_dir" "$inner_cmd"
    if (( keep_shell )); then
        tmux set-option -t "$window_name" remain-on-exit on
    fi
    tmux attach-session -t "$window_name"
fi