#!/usr/bin/env bash
# GNSS Settings for SimCOM modules
set -euo pipefail

DEVICE="/dev/ttyUSB2"
MAX_WAIT=120  # maximum seconds to wait for modem detection

# helper: send AT and optionally print immediate response lines (non-blocking)
send_at() {
    local cmd="$1"
    printf "%s\r" "$cmd" > "$DEVICE"
    timeout 1 cat "$DEVICE" 2>/dev/null || true
}

# handle restart command
if [ "${1:-}" = "restart" ]; then
    echo "Restarting modem..."
    if [ ! -e "$DEVICE" ]; then
        echo "Error: device $DEVICE not found." >&2
        exit 2
    fi
    send_at "AT+CFUN=1,1"
    echo "Modem restart command sent. Restarting service..."
    exit 0
fi

# handle start command (default behavior)
if [ "${1:-start}" != "start" ]; then
    echo "Usage: $0 {start|restart}" >&2
    exit 1
fi

# check if SimTech modem is present
echo "Checking for SimTech modem..."
ELAPSED=0
SIMTECH_FOUND=false

while [ $ELAPSED -lt $MAX_WAIT ]; do
    if lsusb | grep -iq "simtech"; then
        echo "SimTech modem detected in lsusb."
        SIMTECH_FOUND=true
        break
    fi
    
    echo -n "."
    sleep 2
    ELAPSED=$((ELAPSED + 2))
done

if [ "$SIMTECH_FOUND" = false ]; then
    echo ""
    echo "Error: No SimTech modem detected after ${MAX_WAIT}s. Exiting." >&2
    exit 1
fi

# wait for USB device to appear
echo "Waiting for $DEVICE to appear..."
ELAPSED=0
while [ $ELAPSED -lt $MAX_WAIT ]; do
    if [ -e "$DEVICE" ]; then
        echo "$DEVICE found."
        break
    fi
    
    echo -n "."
    sleep 2
    ELAPSED=$((ELAPSED + 2))
done

if [ $ELAPSED -ge $MAX_WAIT ]; then
    echo ""
    echo "Error: Timeout waiting for $DEVICE after ${MAX_WAIT}s." >&2
    exit 2
fi

sleep 10

# stop GNSS if running
echo "Stopping GNSS..."
send_at "AT+CGPS=0"
send_at "AT+CGPS?"
send_at "AT+CGPSAUTO=0"
send_at "AT+CGPSAUTO?"
sleep 0.5

# set SUPL server
echo "Setting SUPL server..."
send_at 'AT+CGPSURL="supl.google.com:7275"'
send_at 'AT+CGPSURL?'
sleep 0.5

# enable XTRA
echo "Enabling XTRA..."
send_at 'AT+CGPSXE=1'
send_at 'AT+CGPSXE?'
send_at 'AT+CGPSXDAUTO=1'
send_at 'AT+CGPSXDAUTO?'
sleep 0.5

# configure GNSS
echo "Configuring GNSS..."
echo "GPS + GLONASS"
send_at 'AT+CGNSSMODE=1,0'
send_at 'AT+CGNSSMODE?'
sleep 1

# start GNSS
echo "Starting GPS with UE-based mode..."
send_at "AT+CGPS=1,2"
send_at "AT+CGPS?"
sleep 0.5

exit 0