#!/bin/bash

# Script to check comprehensive disk statistics
# Author: Alex@portalZINE.de
# Date: 25.11.2025

#####################################
# CONFIGURATION
#####################################
DEFAULT_DEVICE="/dev/sda1"  # Default device to monitor

# Ntfy Configuration
NTFY_URL="https://your-ntfy-server.com/topic"
# Leave the ":", when using a token
NTFY_TOKEN=":your_token_here"
# NTFY_TOKEN="user:password"
NTFY_TITLE="Whatever Title You Want"
#####################################

# Initialize output variable
OUTPUT=""

# Function to add to output
add_output() {
    OUTPUT="${OUTPUT}${1}\n"
}

# Function to display usage
usage() {
    cat << EOF
Usage: $(basename "$0") [OPTIONS] [DEVICE]

Check comprehensive disk statistics for a device.

OPTIONS:
    -h, --help              Show this help message
    -d, --device DEVICE     Specify device to check (e.g., /dev/sda1)
    -q, --quiet             Quiet mode - minimal output
    -v, --verbose           Verbose mode - show all available stats
    -s, --section NAME      Show only specific section(s) (comma-separated)
    -l, --list-sections     List all available sections and exit
    -n, --ntfy              Send notification via ntfy (no console output)
    --ntfy-always           Send ntfy notification AND show console output

AVAILABLE SECTIONS:
    all                 Show all sections (default)
    basic               Basic disk usage (size, used, available)
    inodes              Inode usage statistics
    filesystem          Filesystem information (type, blocks)
    mount               Mount options
    device              Device information (lsblk output)
    io                  I/O statistics (reads, writes, sectors)
    analysis            Usage analysis and warnings
    consumers           Top space consumers (largest directories)

ARGUMENTS:
    DEVICE              Device to check (default: $DEFAULT_DEVICE)

NTFY CONFIGURATION:
    Configure ntfy settings at the top of the script:
    - NTFY_URL          Ntfy server URL
    - NTFY_TOKEN        Authentication token
    - NTFY_TITLE        Notification title

EXAMPLES:
    $(basename "$0")                           # Check default device ($DEFAULT_DEVICE)
    $(basename "$0") /dev/sdb1                 # Check /dev/sdb1
    $(basename "$0") -d /dev/nvme0n1p1         # Check NVMe device
    $(basename "$0") --quiet /dev/sda2         # Quiet mode for /dev/sda2
    $(basename "$0") -s basic                  # Show only basic usage
    $(basename "$0") -s basic,analysis         # Show basic usage and analysis
    $(basename "$0") -s io,consumers /dev/sdb1 # Show I/O stats and top consumers
    $(basename "$0") --list-sections           # List all available sections
    $(basename "$0") --ntfy                    # Send notification only (no output)
    $(basename "$0") --ntfy-always             # Send notification AND show output

EOF
    exit 0
}

# Function to list all available sections
list_sections() {
    cat << EOF
Available Sections:
===================

  all         - Show all sections (default behavior)
  basic       - Basic disk usage information
                • Filesystem name
                • Total size
                • Used space
                • Available space
                • Usage percentage
                • Mount point

  inodes      - Inode usage statistics
                • Total inodes
                • Used inodes
                • Free inodes
                • Inode usage percentage

  filesystem  - Filesystem information
                • Filesystem type (ext4, xfs, etc.)
                • Block size
                • Total blocks
                • Free blocks
                • Available blocks

  mount       - Mount options
                • Full mount command output
                • Mount flags (rw, relatime, etc.)

  device      - Device information
                • Device name
                • Size
                • Type
                • Filesystem type
                • Mount point
                • Label
                • UUID

  io          - I/O statistics
                • Read operations
                • Write operations
                • Sectors read/written
                • Read/write time
                • I/O operations in progress
                • Extended iostat (verbose mode only)

  analysis    - Usage analysis
                • Disk space status (OK/WARNING/CRITICAL)
                • Inode status (OK/WARNING/CRITICAL)
                • Threshold-based alerts

  consumers   - Top space consumers
                • Largest directories on the partition
                • Top 10 (normal) or top 20 (verbose)
                • Human-readable sizes

Usage Examples:
  $(basename "$0") -s basic               # Just the essentials
  $(basename "$0") -s basic,analysis      # Quick health check
  $(basename "$0") -s io                  # I/O performance only
  $(basename "$0") -s all                 # Everything (same as no -s flag)

EOF
    exit 0
}

# Parse command line arguments
DEVICE=""
QUIET_MODE=false
VERBOSE_MODE=false
SECTIONS=""
NTFY_MODE=false
NTFY_ALWAYS=false

while [[ $# -gt 0 ]]; do
    case $1 in
        -h|--help)
            usage
            ;;
        -l|--list-sections)
            list_sections
            ;;
        -d|--device)
            DEVICE="$2"
            shift 2
            ;;
        -q|--quiet)
            QUIET_MODE=true
            shift
            ;;
        -v|--verbose)
            VERBOSE_MODE=true
            shift
            ;;
        -s|--section)
            SECTIONS="$2"
            shift 2
            ;;
        -n|--ntfy)
            NTFY_MODE=true
            shift
            ;;
        --ntfy-always)
            NTFY_ALWAYS=true
            shift
            ;;
        -*)
            echo "Error: Unknown option: $1"
            echo "Use -h or --help for usage information"
            exit 1
            ;;
        *)
            # Assume it's a device path
            if [ -z "$DEVICE" ]; then
                DEVICE="$1"
            else
                echo "Error: Multiple devices specified"
                exit 1
            fi
            shift
            ;;
    esac
done

# Use default device if none specified
if [ -z "$DEVICE" ]; then
    DEVICE="$DEFAULT_DEVICE"
fi

# Function to check if a section should be displayed
should_show_section() {
    local section=$1
    
    # If no sections specified, show all
    if [ -z "$SECTIONS" ]; then
        return 0
    fi
    
    # If 'all' is specified, show everything
    if [[ ",$SECTIONS," == *",all,"* ]]; then
        return 0
    fi
    
    # Check if section is in the comma-separated list
    if [[ ",$SECTIONS," == *",$section,"* ]]; then
        return 0
    fi
    
    return 1
}

add_output "========================================"
add_output "Disk Statistics Report for $DEVICE"
add_output "========================================"
if [ "$QUIET_MODE" = false ]; then
    add_output "Report generated: $(date '+%Y-%m-%d %H:%M:%S')"
fi
add_output ""

# Check if device exists
if [ ! -b "$DEVICE" ]; then
    echo "Error: $DEVICE does not exist or is not a block device"
    exit 1
fi

# Get mount point
MOUNT_POINT=$(df "$DEVICE" 2>/dev/null | awk 'NR==2 {print $6}')

if [ -z "$MOUNT_POINT" ]; then
    echo "Error: $DEVICE is not mounted"
    exit 1
fi

# Quiet mode - show only essential info
if [ "$QUIET_MODE" = true ]; then
    QUIET_INFO=$(df -h "$DEVICE" | awk 'NR==2 {
        print "Device:     " $1
        print "Size:       " $2
        print "Used:       " $3
        print "Available:  " $4
        print "Usage:      " $5
        print "Mount:      " $6
    }')
    add_output "$QUIET_INFO"
    
    USAGE_PERCENT=$(df "$DEVICE" | awk 'NR==2 {print $5}' | sed 's/%//')
    if [ "$USAGE_PERCENT" -ge 90 ]; then
        add_output "Status:     ⚠️  CRITICAL (${USAGE_PERCENT}%)"
    elif [ "$USAGE_PERCENT" -ge 80 ]; then
        add_output "Status:     ⚠️  WARNING (${USAGE_PERCENT}%)"
    else
        add_output "Status:     ✓ OK (${USAGE_PERCENT}%)"
    fi
    
    # Print all output at once
    echo -e "$OUTPUT"
    exit 0
fi

if should_show_section "basic"; then
    add_output "========== BASIC DISK USAGE =========="
    BASIC_USAGE=$(df -h "$DEVICE" | awk 'NR==2 {
        print "  Filesystem:   " $1
        print "  Total Size:   " $2
        print "  Used:         " $3
        print "  Available:    " $4
        print "  Usage:        " $5
        print "  Mount Point:  " $6
    }')
    add_output "$BASIC_USAGE"
    add_output ""
fi

if should_show_section "inodes"; then
    add_output "========== INODE USAGE =========="
    INODE_USAGE=$(df -hi "$DEVICE" | awk 'NR==2 {
        print "  Total Inodes: " $2
        print "  Used Inodes:  " $3
        print "  Free Inodes:  " $4
        print "  Inode Usage:  " $5
    }')
    add_output "$INODE_USAGE"
    add_output ""
fi

if should_show_section "filesystem"; then
    add_output "========== FILESYSTEM INFORMATION =========="
    # Filesystem type
    FS_TYPE=$(df -T "$DEVICE" | awk 'NR==2 {print $2}')
    add_output "  Filesystem Type: $FS_TYPE"

    # Block size information
    BLOCK_SIZE=$(stat -f -c %s "$MOUNT_POINT" 2>/dev/null)
    if [ -n "$BLOCK_SIZE" ]; then
        add_output "  Block Size:      $BLOCK_SIZE bytes"
    fi

    # Total blocks
    TOTAL_BLOCKS=$(stat -f -c %b "$MOUNT_POINT" 2>/dev/null)
    FREE_BLOCKS=$(stat -f -c %f "$MOUNT_POINT" 2>/dev/null)
    AVAIL_BLOCKS=$(stat -f -c %a "$MOUNT_POINT" 2>/dev/null)

    if [ -n "$TOTAL_BLOCKS" ]; then
        add_output "  Total Blocks:    $TOTAL_BLOCKS"
        add_output "  Free Blocks:     $FREE_BLOCKS"
        add_output "  Available:       $AVAIL_BLOCKS"
    fi
    add_output ""
fi

if should_show_section "mount"; then
    add_output "========== MOUNT OPTIONS =========="
    MOUNT_INFO=$(mount | grep "$DEVICE")
    if [ -n "$MOUNT_INFO" ]; then
        add_output "  $MOUNT_INFO"
    fi
    add_output ""
fi

if should_show_section "device"; then
    add_output "========== DISK DEVICE INFO =========="
    if command -v lsblk &> /dev/null; then
        LSBLK_INFO=$(lsblk "$DEVICE" -o NAME,SIZE,TYPE,FSTYPE,MOUNTPOINT,LABEL,UUID 2>/dev/null | sed 's/^/  /')
        add_output "$LSBLK_INFO"
    fi
    add_output ""
fi

if should_show_section "io"; then
    add_output "========== I/O STATISTICS =========="
    if [ -f /proc/diskstats ]; then
        # Extract device name without /dev/ prefix
        DEVICE_NAME=$(basename "$DEVICE")
        # Extract stats for the device
        DISK_STATS=$(grep " $DEVICE_NAME " /proc/diskstats)
        if [ -n "$DISK_STATS" ]; then
            IO_STATS=$(echo "$DISK_STATS" | awk '{
                print "  Device:          " $3
                print "  Reads:           " $4
                print "  Reads Merged:    " $5
                print "  Sectors Read:    " $6
                print "  Read Time (ms):  " $7
                print "  Writes:          " $8
                print "  Writes Merged:   " $9
                print "  Sectors Written: " $10
                print "  Write Time (ms): " $11
                print "  I/Os in Progress:" $12
                print "  I/O Time (ms):   " $13
            }')
            add_output "$IO_STATS"
        fi
    fi

    # iostat if available - show in verbose mode or if explicitly installed
    if command -v iostat &> /dev/null && [ "$VERBOSE_MODE" = true ]; then
        add_output ""
        add_output "  Extended I/O Stats:"
        IOSTAT_INFO=$(iostat -x "$DEVICE" 1 1 2>/dev/null | tail -n +4 | sed 's/^/    /')
        add_output "$IOSTAT_INFO"
    fi
    add_output ""
fi

if should_show_section "analysis"; then
    add_output "========== USAGE ANALYSIS =========="

    # Get usage percentage as a number
    USAGE_PERCENT=$(df "$DEVICE" | awk 'NR==2 {print $5}' | sed 's/%//')
    INODE_PERCENT=$(df -i "$DEVICE" | awk 'NR==2 {print $5}' | sed 's/%//')

    # Disk space warning
    add_output "  Disk Space Status:"
    if [ "$USAGE_PERCENT" -ge 90 ]; then
        add_output "    ⚠️  CRITICAL: Disk usage is critically high (${USAGE_PERCENT}%)!"
    elif [ "$USAGE_PERCENT" -ge 80 ]; then
        add_output "    ⚠️  WARNING: Disk usage is high (${USAGE_PERCENT}%)"
    elif [ "$USAGE_PERCENT" -ge 70 ]; then
        add_output "    ⚡ NOTICE: Disk usage is moderate (${USAGE_PERCENT}%)"
    else
        add_output "    ✓ OK: Disk usage is within normal range (${USAGE_PERCENT}%)"
    fi

    # Inode warning
    add_output ""
    add_output "  Inode Status:"
    if [ "$INODE_PERCENT" -ge 90 ]; then
        add_output "    ⚠️  CRITICAL: Inode usage is critically high (${INODE_PERCENT}%)!"
    elif [ "$INODE_PERCENT" -ge 80 ]; then
        add_output "    ⚠️  WARNING: Inode usage is high (${INODE_PERCENT}%)"
    else
        add_output "    ✓ OK: Inode usage is within normal range (${INODE_PERCENT}%)"
    fi
    add_output ""
fi

if should_show_section "consumers"; then
    add_output "========== TOP SPACE CONSUMERS =========="
    if [ -d "$MOUNT_POINT" ]; then
        add_output "  Largest directories in $MOUNT_POINT:"
        if [ "$VERBOSE_MODE" = true ]; then
            # Show top 20 in verbose mode
            TOP_DIRS=$(du -h "$MOUNT_POINT" --max-depth=1 2>/dev/null | sort -rh | head -20 | sed 's/^/    /')
        else
            # Show top 10 in normal mode
            TOP_DIRS=$(du -h "$MOUNT_POINT" --max-depth=1 2>/dev/null | sort -rh | head -10 | sed 's/^/    /')
        fi
        add_output "$TOP_DIRS"
    fi
    add_output ""
fi

add_output "========================================"
add_output "Report completed: $(date '+%Y-%m-%d %H:%M:%S')"
add_output "========================================"

# Function to send ntfy notification
send_ntfy() {
    local message="$1"
    local priority="${2:-default}"
    local tags="${3:-}"
    
    if [ -z "$NTFY_URL" ] || [ -z "$NTFY_TOKEN" ]; then
        echo "Error: Ntfy configuration is incomplete"
        return 1
    fi
    
    local curl_args=(-u "$NTFY_TOKEN")
    
    if [ -n "$NTFY_TITLE" ]; then
        curl_args+=(-H "Title: $NTFY_TITLE")
    fi
    
    if [ -n "$priority" ] && [ "$priority" != "default" ]; then
        curl_args+=(-H "Priority: $priority")
    fi
    
    if [ -n "$tags" ]; then
        curl_args+=(-H "Tags: $tags")
    fi
    
    curl_args+=(-d "$message" "$NTFY_URL")
    
    curl -s "${curl_args[@]}" > /dev/null
    return $?
}

# Prepare notification if ntfy is enabled
if [ "$NTFY_MODE" = true ] || [ "$NTFY_ALWAYS" = true ]; then
    # Get key metrics for determining priority
    USAGE_PERCENT=$(df "$DEVICE" | awk 'NR==2 {print $5}' | sed 's/%//')
    INODE_PERCENT=$(df -i "$DEVICE" | awk 'NR==2 {print $5}' | sed 's/%//')
    
    # Determine priority and tags based on usage
    PRIORITY="default"
    TAGS="white_check_mark"
    
    if [ "$USAGE_PERCENT" -ge 90 ] || [ "$INODE_PERCENT" -ge 90 ]; then
        PRIORITY="urgent"
        TAGS="warning,skull"
    elif [ "$USAGE_PERCENT" -ge 80 ] || [ "$INODE_PERCENT" -ge 80 ]; then
        PRIORITY="high"
        TAGS="warning"
    elif [ "$USAGE_PERCENT" -ge 70 ] || [ "$INODE_PERCENT" -ge 70 ]; then
        PRIORITY="default"
        TAGS="zap"
    fi
    
    # Send the full output as notification
    NTFY_MESSAGE=$(echo -e "$OUTPUT")
    
    # Send notification
    if send_ntfy "$NTFY_MESSAGE" "$PRIORITY" "$TAGS"; then
        if [ "$NTFY_MODE" = true ]; then
            echo "Notification sent successfully to ntfy"
            exit 0
        fi
    else
        echo "Error: Failed to send ntfy notification"
        if [ "$NTFY_MODE" = true ]; then
            exit 1
        fi
    fi
fi

# Print all output at once at the end (unless ntfy-only mode)
if [ "$NTFY_MODE" = false ]; then
    echo -e "$OUTPUT"
fi