#!/usr/bin/env bash
#===============================================================================
#
# CREATED : 2026-02-21
# UPDATED :
# USAGE   :
# DESC    : Hack tmux session launcher.  Reads a YAML file to create a tmux #           session with multiple windows and commands.
# NOTES   :
# AUTHOR  : chawley
#
#===============================================================================

# Path to the YAML configuration file
TMUX_CONFIG_FILE="${HOME}/.config/tmux-menu/sessions.yaml"

# Check for yq (YAML processor)
if ! command -v yq &> /dev/null; then
    echo "Error: 'yq' command not found."
    echo "Please install yq (https://github.com/mikefarah/yq) to use this script."
    echo "Example: 'sudo snap install yq' or 'brew install yq'"
    exit 1
fi
# check for command line argument
# Tips from:
# http://stackoverflow.com/questions/7832080/test-if-a-variable-is-set-in-bash-when-using-set-o-nounset
if [ -z "${1:-}" ]; then
	session="undefined"
else
	session=$1
fi

echo ""
echo ""
echo "##################################"
echo "TMUX Hack Session Launcher"
echo "##################################"
echo "Launching Session: $session"

# NO TMUX NESTING ALLOWED
if [ ! -z $TMUX ]; then
	echo "You are in a session already.  NO NESTING ALLOWED"
	echo "-------------------------------------------------"
	exit 1
fi


# if session is active, switch to it.
if tmux has-session -t "${session}" 2>/dev/null; then
    echo "Session '${session}' already active. Attaching..."
    tmux attach-session -t "${session}"
    exit 0
fi

# Check if the config file exists
if [ ! -f "${TMUX_CONFIG_FILE}" ]; then
    echo "Error: tmux session configuration file not found at '${TMUX_CONFIG_FILE}'."
    echo "Please create it with your session definitions."
    exit 1
fi

# Check if the requested session exists in the YAML file
if ! yq e ".sessions.${session}" "${TMUX_CONFIG_FILE}" &> /dev/null; then
    echo "### ERROR No Such Session ###"
    echo "Usage: $(basename "$0") <session_name>"
    echo "Available Sessions from '${TMUX_CONFIG_FILE}':"
    echo "---------------------------------------"
    yq e '.sessions | keys | .[]' "${TMUX_CONFIG_FILE}" 2>/dev/null || echo "No sessions defined."
    echo ""
    echo "Active tmux Sessions:"
    echo "---------------------"
    tmux list-sessions 2>/dev/null || echo "No active sessions."
    exit 1
fi

echo "Creating new session '${session}' from '${TMUX_CONFIG_FILE}'..."

# Get the number of windows for the session
num_windows=$(yq e ".sessions.${session}.windows | length" "${TMUX_CONFIG_FILE}")

if [[ "${num_windows}" -eq 0 ]]; then
    echo "Error: Session '${session}' has no windows defined in '${TMUX_CONFIG_FILE}'."
    exit 1
fi

# Create the first window (which also creates the session)
first_window_name=$(yq e ".sessions.${session}.windows[0].name" "${TMUX_CONFIG_FILE}")
first_window_command=$(yq e ".sessions.${session}.windows[0].command // \"\"" "${TMUX_CONFIG_FILE}")

if [[ -z "${first_window_command}" ]]; then
    tmux new-session -d -s "${session}" -n "${first_window_name}"
else
    tmux new-session -d -s "${session}" -n "${first_window_name}" "${first_window_command}"
fi

# Create subsequent windows
for ((i=1; i<num_windows; i++)); do
    window_name=$(yq e ".sessions.${session}.windows[${i}].name" "${TMUX_CONFIG_FILE}")
    window_command=$(yq e ".sessions.${session}.windows[${i}].command // \"\"" "${TMUX_CONFIG_FILE}")

    if [[ -z "${window_command}" ]]; then
        tmux new-window -t "${session}:${i}" -n "${window_name}"
    else
        tmux new-window -t "${session}:${i}" -n "${window_name}" "${window_command}"
    fi
done

# Attach to the newly created session
tmux attach-session -t "${session}"