#!/bin/bash

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
. "${SCRIPT_DIR}/../share/logging.sh"
. "${SCRIPT_DIR}/../share/os-detection.sh"

LOGFILE=/var/log/disk_usage.log
OS_TYPE=$(DetectOS)

# Create log file with proper error handling
if ! touch "$LOGFILE" 2>/dev/null; then
    LogError "Cannot create log file $LOGFILE"
    exit 1
fi
chmod 644 "$LOGFILE" 2>/dev/null

LogInformation "Starting disk usage monitoring (OS: $OS_TYPE)"

for i in {1..6}; do
    timestamp=$(GetTimestamp)
    
    # Use process substitution instead of pipe to avoid subshell issues
    if [[ "$OS_TYPE" == "macos" ]]; then
        # macOS df format: Filesystem 512-blocks Used Available Capacity iused ifree %iused  Mounted on
        # Mount points can have spaces, so we need to handle the full line
        while IFS= read -r line; do
            # Skip header line
            if [[ "$line" =~ ^Filesystem ]]; then
                continue
            fi
            
            # Extract fields using awk (handles multi-word mount points)
            filesystem=$(echo "$line" | awk '{print $1}')
            blocks=$(echo "$line" | awk '{print $2}')
            used=$(echo "$line" | awk '{print $3}')
            # Mount point is everything from column 9 onwards
            mount=$(echo "$line" | awk '{for(i=9;i<=NF;i++) printf "%s%s", $i, (i<NF?" ":""); print ""}')
            
            # Skip entries with 0 blocks (pseudo filesystems) or filesystem starting with dash
            if [[ -n "$mount" && -n "$used" && -n "$blocks" && "$blocks" != "0" && "$filesystem" != "-" ]]; then
                used_bytes=$((used * 512))
                total_bytes=$((blocks * 512))
                echo "$timestamp $mount $used_bytes $total_bytes" >> "$LOGFILE"
            fi
        done < <(df 2>/dev/null)
    else
        # Linux df with --output flag
        while read -r mount used total; do
            if [[ -n "$mount" && -n "$used" && -n "$total" ]]; then
                echo "$timestamp $mount $used $total" >> "$LOGFILE"
            fi
        done < <(df --output=target,used,size -B1 2>/dev/null | tail -n +2)
    fi
    
    LogInformation "Disk usage data collected (iteration $i/6)"
    
    if [ $i -lt 6 ]; then
        sleep 10
    fi
done

LogInformation "Disk usage monitoring completed"