#!/bin/sh

echo "Content-type: text/plain"
echo ""

# Configuration
CACHE_FILE="/tmp/wifi_iface_cache.map"
DATE_FILE="/tmp/wifi_last_scan.date"
LOCK_DIR="/tmp/wifi_scan.lock"
# PID-based temp file to ensure zero collision between concurrent writes
MY_TMP="/tmp/wifi_cache.$$.tmp"
TODAY=$(date +%Y-%m-%d)

perform_scan() {
    # Initialize our private temp file
    : > "$MY_TMP"

    # Format: label|phy_prefix|exact_ssid
    cat <<EOF | while IFS="|" read -r label prefix ssid; do
m2|phy0|Konepaja
g2|phy0|Konepaja vieras
a2|phy0|as
m5|phy1|Konepaja
g5|phy1|Konepaja vieras
EOF
        for i in 0 1 2 3 4 5; do
            iface="${prefix}-ap${i}"
            if iwinfo "$iface" info 2>/dev/null | grep -q "ESSID: \"$ssid\""; then
                echo "${label}:${iface}" >> "$MY_TMP"
                break
            fi
        done
    done

    # Move our private file to the global cache (Atomic Move)
    mv "$MY_TMP" "$CACHE_FILE"
    echo "$TODAY" > "$DATE_FILE"
}

# --- Atomic Lock & Cache Logic ---
needs_refresh=0
if [ ! -f "$CACHE_FILE" ] || [ ! -f "$DATE_FILE" ] || [ "$(cat "$DATE_FILE" 2>/dev/null)" != "$TODAY" ]; then
    needs_refresh=1
fi

if [ "$needs_refresh" -eq 1 ]; then
    # Try to acquire the lock
    if mkdir "$LOCK_DIR" 2>/dev/null; then
        # This process is the designated "Scanner"
        perform_scan
        rmdir "$LOCK_DIR"
    else
        # Another process is already scanning. 
        # Wait up to 2 seconds for them to finish so we don't return empty results.
        counter=0
        while [ -d "$LOCK_DIR" ] && [ $counter -lt 10 ]; do
            sleep 0.2
            counter=$((counter + 1))
        done
    fi
fi

# --- Execution ---
# Always read from the final CACHE_FILE
if [ -s "$CACHE_FILE" ]; then
    while IFS=: read -r label iface; do
       # iwinfo "$iface" assoclist | grep 'ms ago' | awk -v lbl="$label" '{print lbl " " $1;}'
        ubus call hostapd."$iface" get_clients 2>/dev/null | grep -oE "([0-9A-Fa-f]{2}:){5}[0-9A-Fa-f]{2}" | awk -v lbl="$label" '{print lbl " " toupper($1);}'
    done < "$CACHE_FILE"
fi

# Cleanup: if this process's temp file exists (due to a failure), remove it
rm -f "$MY_TMP"