#!/usr/bin/env bash
# Install or update we_monitor as a systemd user service.
#
# Fresh install:
#   chmod +x install.sh
#   ./install.sh
#   # then edit ~/.config/we_monitor/credentials.json
#   systemctl --user start we_monitor
#
# Update (code already pulled via git):
#   ./install.sh
#   (restarts the service automatically if it was running)

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
SERVICE_NAME="we_monitor"
CREDS_DIR="$HOME/.config/we_monitor"
CREDS_FILE="$CREDS_DIR/credentials.json"
SYSTEMD_DIR="$HOME/.config/systemd/user"
SERVICE_FILE="$SYSTEMD_DIR/$SERVICE_NAME.service"
LOG_DIR="$SCRIPT_DIR/logs"

VENV="$SCRIPT_DIR/.venv"
PYTHON="$VENV/bin/python"

# detect fresh install vs update
IS_UPDATE=false
WAS_ACTIVE=false
if systemctl --user is-enabled "$SERVICE_NAME" &>/dev/null; then
    IS_UPDATE=true
    if systemctl --user is-active "$SERVICE_NAME" &>/dev/null; then
        WAS_ACTIVE=true
    fi
fi

if $IS_UPDATE; then
    echo "==> we_monitor updater"
else
    echo "==> we_monitor installer"
fi
echo "    Project : $SCRIPT_DIR"
echo "    User    : $USER"
echo ""

# ── 1. virtual environment ────────────────────────────────────────────────────
if [[ ! -x "$PYTHON" ]]; then
    echo "==> Creating virtual environment : $VENV"
    python3 -m venv "$VENV"
else
    echo "==> Virtual environment exists   : $VENV"
fi

echo "==> Installing / updating dependencies"
"$VENV/bin/pip" install --quiet --upgrade pip
"$VENV/bin/pip" install --quiet --upgrade -r "$SCRIPT_DIR/requirements.txt"
echo "    Python  : $PYTHON"
echo ""

# ── 2. credentials template (only on fresh install) ───────────────────────────
mkdir -p "$CREDS_DIR"
chmod 700 "$CREDS_DIR"

if [[ ! -f "$CREDS_FILE" ]]; then
    cat > "$CREDS_FILE" <<'EOF'
{
  "credentials": {
    "username": "me@example.com",
    "password": "secret"
  },
  "vin":        "",
  "domains":    ["charging", "electric_drive", "connectivity"],
  "interval_s": 300,
  "host":       "0.0.0.0",
  "port":       9999,
  "log_dir":    "./logs",
  "diff":       false
}
EOF
    chmod 600 "$CREDS_FILE"
    echo "==> Created credentials template : $CREDS_FILE"
    echo "    *** Edit this file before starting the service! ***"
else
    echo "==> Credentials file exists      : $CREDS_FILE"
fi

# ── 3. log directory ──────────────────────────────────────────────────────────
mkdir -p "$LOG_DIR"
echo "==> Log directory                : $LOG_DIR"

# ── 4. systemd user service ───────────────────────────────────────────────────
mkdir -p "$SYSTEMD_DIR"

cat > "$SERVICE_FILE" <<EOF
[Unit]
Description=CarConnectivity vehicle data collector
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
WorkingDirectory=$SCRIPT_DIR
ExecStart=$PYTHON $SCRIPT_DIR/collect.py -c $CREDS_FILE
Restart=on-failure
RestartSec=60
StandardOutput=journal
StandardError=journal
SyslogIdentifier=$SERVICE_NAME

[Install]
WantedBy=default.target
EOF

echo "==> Installed service unit       : $SERVICE_FILE"

# ── 5. enable linger (service survives logout / starts at boot) ───────────────
if loginctl enable-linger "$USER" 2>/dev/null; then
    echo "==> Linger enabled for $USER (service starts at boot)"
else
    echo "    Note: could not enable linger — service runs only while logged in"
    echo "    Run as root to fix: loginctl enable-linger $USER"
fi

# ── 6. reload systemd and enable / restart ────────────────────────────────────
systemctl --user daemon-reload
systemctl --user enable "$SERVICE_NAME"

if $WAS_ACTIVE; then
    systemctl --user restart "$SERVICE_NAME"
    echo "==> Service restarted"
fi

echo ""
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
if $IS_UPDATE; then
    echo " Update complete."
    echo ""
    if $WAS_ACTIVE; then
        echo " Service was restarted automatically."
    else
        echo " Service was not running — start it manually if needed:"
        echo "        systemctl --user start $SERVICE_NAME"
    fi
else
    echo " Installation complete."
    echo ""
    echo " Next steps:"
    echo "   1. Edit credentials (username, password, vin, interval_s, …):"
    echo "        \$EDITOR $CREDS_FILE"
    echo ""
    echo "   2. Start the service:"
    echo "        systemctl --user start $SERVICE_NAME"
fi
echo ""
echo "   Check status : systemctl --user status $SERVICE_NAME"
echo "   Follow logs  : journalctl --user -u $SERVICE_NAME -f"
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"