#!/bin/bash

INTERFACE="br0"
TEMP_FILE="/tmp/waybar_network_$INTERFACE"
MAX_AGE=10

# Check if interface exists
if [ ! -d "/sys/class/net/$INTERFACE" ]; then
    echo '{"text":"󰈀 No Interface","tooltip":"Interface '$INTERFACE' not found"}'
    exit 1
fi

# Get current values
RX_BYTES=$(cat /sys/class/net/$INTERFACE/statistics/rx_bytes)
TX_BYTES=$(cat /sys/class/net/$INTERFACE/statistics/tx_bytes)
CURRENT_TIME=$(date +%s)

# Check if temp file exists and is recent
TEMP_FILE_VALID=0
if [ -f "$TEMP_FILE" ]; then
    read PREV_RX PREV_TX PREV_TIME < "$TEMP_FILE"
    TIME_DIFF=$((CURRENT_TIME - PREV_TIME))
    
    # Accept temp file if it's recent (0 seconds is OK, negative or too old is not)
    if [ $TIME_DIFF -ge 0 ] && [ $TIME_DIFF -le $MAX_AGE ]; then
        TEMP_FILE_VALID=1
    fi
fi

# If no valid temp file, initialize
if [ $TEMP_FILE_VALID -eq 0 ]; then
    echo "$RX_BYTES $TX_BYTES $CURRENT_TIME" > "$TEMP_FILE"
    echo '{"text":"'${INTERFACE}' ↑ 0.0K ↓ 0.0K","tooltip":"Upload: 0.0 KB/s\\nDownload: 0.0 KB/s"}'
    exit 0
fi

# If TIME_DIFF is 0, return the last calculated result without updating temp file
if [ $TIME_DIFF -eq 0 ]; then
    # Try to read cached result from a secondary file
    CACHE_FILE="/tmp/waybar_network_cache_$INTERFACE"
    if [ -f "$CACHE_FILE" ]; then
        cat "$CACHE_FILE"
        exit 0
    else
        # No cache, show 0.0K
        echo '{"text":"'${INTERFACE}' ↑ 0.0K ↓ 0.0K","tooltip":"Upload: 0.0 KB/s\\nDownload: 0.0 KB/s"}'
        exit 0
    fi
fi

# Calculate rates (bytes per second)
RX_RATE=$(( (RX_BYTES - PREV_RX) / TIME_DIFF ))
TX_RATE=$(( (TX_BYTES - PREV_TX) / TIME_DIFF ))

# Handle negative values (counter reset) or unrealistic high values
if [ $RX_RATE -lt 0 ] || [ $RX_RATE -gt 1073741824 ]; then RX_RATE=0; fi
if [ $TX_RATE -lt 0 ] || [ $TX_RATE -gt 1073741824 ]; then TX_RATE=0; fi

# Convert to KB/s with one decimal place
RX_KB_TENTHS=$(( (RX_RATE * 10) / 1024 ))
TX_KB_TENTHS=$(( (TX_RATE * 10) / 1024 ))

# Split into whole and decimal parts
RX_WHOLE=$((RX_KB_TENTHS / 10))
RX_DECIMAL=$((RX_KB_TENTHS % 10))
TX_WHOLE=$((TX_KB_TENTHS / 10))
TX_DECIMAL=$((TX_KB_TENTHS % 10))

# Format output with fixed width
RESULT=$(printf '{"text":"'${INTERFACE}' ↑%2d.%dK ↓%2d.%dK","tooltip":"Upload: %d.%d KB/s\\nDownload: %d.%d KB/s"}' \
    "$TX_WHOLE" "$TX_DECIMAL" "$RX_WHOLE" "$RX_DECIMAL" \
    "$TX_WHOLE" "$TX_DECIMAL" "$RX_WHOLE" "$RX_DECIMAL")

echo "$RESULT"

# Store current values for next iteration AND cache the result
echo "$RX_BYTES $TX_BYTES $CURRENT_TIME" > "$TEMP_FILE"
echo "$RESULT" > "/tmp/waybar_network_cache_$INTERFACE"