#!/bin/bash

# Plex Backup Validation and Monitoring Script
# Usage: ./validate-plex-backups.sh [--fix] [--report]

set -e

RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m'

# Configuration
SCRIPT_DIR="$(dirname "$(readlink -f "$0")")"
BACKUP_ROOT="/mnt/share/media/backups/plex"
JSON_LOG_FILE="$SCRIPT_DIR/logs/plex-backup.json"
REPORT_FILE="$SCRIPT_DIR/logs/backup-validation-$(date +%Y%m%d_%H%M%S).log"

# Expected files in backup
EXPECTED_FILES=(
    "com.plexapp.plugins.library.db"
    "com.plexapp.plugins.library.blobs.db"
    "Preferences.xml"
)

# Files that may not exist in older backups (with approximate introduction dates)
# This helps provide better context for missing files
declare -A OPTIONAL_FILES=(
    ["com.plexapp.plugins.library.blobs.db"]="20250526_144500"  # Blobs DB introduced between 07:55 and 14:45 on 5/26
)

log_message() {
    local message="$1"
    local clean_message="$2"
    
    # Display colored message to terminal
    echo -e "$(date '+%H:%M:%S') $message"
    
    # Strip ANSI codes and log clean version to file
    if [ -n "$clean_message" ]; then
        echo "$(date '+%H:%M:%S') $clean_message" >> "$REPORT_FILE"
    else
        # Strip ANSI escape codes for file logging
        echo "$(date '+%H:%M:%S') $message" | sed 's/\x1b\[[0-9;]*m//g' >> "$REPORT_FILE"
    fi
}

log_error() {
    log_message "${RED}ERROR: $1${NC}" "ERROR: $1"
}

log_success() {
    log_message "${GREEN}SUCCESS: $1${NC}" "SUCCESS: $1"
}

log_warning() {
    log_message "${YELLOW}WARNING: $1${NC}" "WARNING: $1"
}

log_info() {
    log_message "${BLUE}INFO: $1${NC}" "INFO: $1"
}

# Check dependencies
check_dependencies() {
    local missing_deps=()
    
    # Check for required commands
    if ! command -v tar >/dev/null 2>&1; then
        missing_deps+=("tar")
    fi
    
    if ! command -v jq >/dev/null 2>&1; then
        missing_deps+=("jq")
    fi
    
    if ! command -v find >/dev/null 2>&1; then
        missing_deps+=("find")
    fi
    
    if ! command -v df >/dev/null 2>&1; then
        missing_deps+=("df")
    fi
    
    if ! command -v du >/dev/null 2>&1; then
        missing_deps+=("du")
    fi
    
    if [ ${#missing_deps[@]} -gt 0 ]; then
        log_error "Missing required dependencies: ${missing_deps[*]}"
        log_info "Please install missing dependencies before running this script"
        return 1
    fi
    
    return 0
}

# Check backup directory structure
validate_backup_structure() {
    log_info "Validating backup directory structure..."
    
    if [ ! -d "$BACKUP_ROOT" ]; then
        log_error "Backup root directory not found: $BACKUP_ROOT"
        return 1
    fi
    
    local backup_count=$(find "$BACKUP_ROOT" -maxdepth 1 -type f -name "plex-backup-*.tar.gz" | wc -l)
    log_info "Found $backup_count backup files"
    
    if [ "$backup_count" -eq 0 ]; then
        log_warning "No backup files found"
        return 1
    fi
    
    return 0
}

# Validate individual backup
validate_backup() {
    local backup_file="$1"
    local backup_name=$(basename "$backup_file")
    local errors=0
    
    log_info "Validating backup: $backup_name"
    
    # Check if file exists and is readable
    if [ ! -f "$backup_file" ] || [ ! -r "$backup_file" ]; then
        log_error "Backup file not accessible: $backup_file"
        return 1
    fi
    
    # Test archive integrity
    if ! tar -tzf "$backup_file" >/dev/null 2>&1; then
        log_error "Archive integrity check failed: $backup_name"
        errors=$((errors + 1))
    else
        log_success "Archive integrity check passed: $backup_name"
        
        # Check for expected files in archive
        local archive_contents=$(tar -tzf "$backup_file" 2>/dev/null)
        
        # Check if this is a legacy backup with dated subdirectory
        local has_dated_subdir=false
        if echo "$archive_contents" | grep -q "^\./[0-9]\{8\}/" || echo "$archive_contents" | grep -q "^[0-9]\{8\}/"; then
            has_dated_subdir=true
            log_info "  Detected legacy backup format with dated subdirectory"
        fi
        
        for file in "${EXPECTED_FILES[@]}"; do
            local file_found=false
            
            if [ "$has_dated_subdir" = true ]; then
                # For legacy backups, look for files in dated subdirectory (with or without timestamps)
                if echo "$archive_contents" | grep -q "^\./[0-9]\{8\}/$file" || \
                   echo "$archive_contents" | grep -q "^\./[0-9]\{8\}/$file\.[0-9]\{8\}_[0-9]\{6\}$" || \
                   echo "$archive_contents" | grep -q "^[0-9]\{8\}/$file" || \
                   echo "$archive_contents" | grep -q "^[0-9]\{8\}/$file\.[0-9]\{8\}_[0-9]\{6\}$"; then
                    file_found=true
                fi
            else
                # For new backups, look for files at root level
                if echo "$archive_contents" | grep -q "^\./$file$" || \
                   echo "$archive_contents" | grep -q "^$file$"; then
                    file_found=true
                fi
            fi
            
            if [ "$file_found" = true ]; then
                log_success "  Found: $file"
            else
                # Check if this is an optional file that might not exist in older backups
                local backup_name=$(basename "$backup_file")
                local backup_datetime=$(echo "$backup_name" | sed 's/plex-backup-\([0-9]\{8\}_[0-9]\{6\}\)\.tar\.gz/\1/')
                
                if [[ -n "${OPTIONAL_FILES[$file]}" ]] && [[ "$backup_datetime" < "${OPTIONAL_FILES[$file]}" ]]; then
                    log_warning "  Missing file (expected for backup date): $file"
                    log_info "    Note: $file was introduced around ${OPTIONAL_FILES[$file]}, this backup is from $backup_datetime"
                else
                    log_error "  Missing file: $file"
                    errors=$((errors + 1))
                fi
            fi
        done
        
        # Check for unexpected files (more lenient for legacy backups)
        local unexpected_files=()
        while IFS= read -r line; do
            # Skip directory entries and current directory marker
            if [[ "$line" == "./" ]] || [[ "$line" == */ ]] || [[ -z "$line" ]]; then
                continue
            fi
            
            # Extract filename from path (handle both legacy and new formats)
            local filename=""
            if [[ "$line" =~ ^\./[0-9]{8}/(.+)$ ]] || [[ "$line" =~ ^[0-9]{8}/(.+)$ ]]; then
                # Legacy format: extract filename from dated subdirectory
                filename="${BASH_REMATCH[1]}"
                # Remove timestamp suffix if present
                filename=$(echo "$filename" | sed 's/\.[0-9]\{8\}_[0-9]\{6\}$//')
            elif [[ "$line" =~ ^\./(.+)$ ]]; then
                # New format: extract filename from ./ prefix
                filename="${BASH_REMATCH[1]}"
            else
                # Direct filename
                filename="$line"
            fi
            
            # Check if this is an expected file
            local is_expected=false
            for expected_file in "${EXPECTED_FILES[@]}"; do
                if [[ "$filename" == "$expected_file" ]]; then
                    is_expected=true
                    break
                fi
            done
            
            if [ "$is_expected" = false ]; then
                unexpected_files+=("$line")
            fi
        done <<< "$archive_contents"
        
        # Report unexpected files if any found
        if [ ${#unexpected_files[@]} -gt 0 ]; then
            for unexpected_file in "${unexpected_files[@]}"; do
                log_warning "  Unexpected file: $unexpected_file"
            done
        fi
    fi
    
    return $errors
}

# Check backup freshness
check_backup_freshness() {
    log_info "Checking backup freshness..."
    
    local latest_backup=$(find "$BACKUP_ROOT" -maxdepth 1 -type f -name "plex-backup-*.tar.gz" 2>/dev/null | sort | tail -1)
    
    if [ -z "$latest_backup" ]; then
        log_error "No backups found"
        return 1
    fi
    
    local backup_filename=$(basename "$latest_backup")
    # Extract date from filename: plex-backup-YYYYMMDD_HHMMSS.tar.gz
    local backup_datetime=$(echo "$backup_filename" | sed 's/plex-backup-\([0-9]\{8\}_[0-9]\{6\}\)\.tar\.gz/\1/')
    
    # Validate that we extracted a valid datetime
    if [[ ! "$backup_datetime" =~ ^[0-9]{8}_[0-9]{6}$ ]]; then
        log_error "Could not parse backup date from filename: $backup_filename"
        return 1
    fi
    
    local backup_date="${backup_datetime%_*}"  # Remove time part
    
    # Validate date format and convert to timestamp
    if ! backup_timestamp=$(date -d "${backup_date:0:4}-${backup_date:4:2}-${backup_date:6:2}" +%s 2>/dev/null); then
        log_error "Invalid backup date format: $backup_date"
        return 1
    fi
    
    local current_timestamp=$(date +%s)
    local age_days=$(( (current_timestamp - backup_timestamp) / 86400 ))
    
    log_info "Latest backup: $backup_datetime ($age_days days old)"
    
    if [ "$age_days" -gt 7 ]; then
        log_warning "Latest backup is older than 7 days"
        return 1
    elif [ "$age_days" -gt 3 ]; then
        log_warning "Latest backup is older than 3 days"
    else
        log_success "Latest backup is recent"
    fi
    
    return 0
}

# Validate JSON log file
validate_json_log() {
    log_info "Validating JSON log file..."
    
    if [ ! -f "$JSON_LOG_FILE" ]; then
        log_error "JSON log file not found: $JSON_LOG_FILE"
        return 1
    fi
    
    # Check if jq is available (should be caught by dependency check)
    if ! command -v jq >/dev/null 2>&1; then
        log_error "jq command not found - cannot validate JSON"
        return 1
    fi
    
    # Validate JSON syntax
    local jq_output
    if ! jq_output=$(jq empty "$JSON_LOG_FILE" 2>&1); then
        log_error "JSON log file is invalid: $jq_output"
        return 1
    fi
    
    # Get entry count safely
    local entry_count
    if ! entry_count=$(jq 'length' "$JSON_LOG_FILE" 2>/dev/null); then
        log_error "Could not count entries in JSON log file"
        return 1
    fi
    
    log_success "JSON log file is valid ($entry_count entries)"
    return 0
}

# Check backup file sizes for anomalies
check_backup_sizes() {
    log_info "Checking backup file sizes..."
    
    local backup_files=()
    local backup_sizes=()
    local total_size=0
    
    # Collect backup files and their sizes
    while IFS= read -r backup_file; do
        if [ -f "$backup_file" ] && [ -r "$backup_file" ]; then
            backup_files+=("$backup_file")
            local size=$(stat -f%z "$backup_file" 2>/dev/null || stat -c%s "$backup_file" 2>/dev/null || echo "0")
            backup_sizes+=("$size")
            total_size=$((total_size + size))
        fi
    done < <(find "$BACKUP_ROOT" -maxdepth 1 -type f -name "plex-backup-*.tar.gz" 2>/dev/null | sort)
    
    if [ ${#backup_files[@]} -eq 0 ]; then
        log_warning "No backup files found for size analysis"
        return 1
    fi
    
    # Calculate average size
    local avg_size=$((total_size / ${#backup_files[@]}))
    local human_total=$(numfmt --to=iec "$total_size" 2>/dev/null || echo "${total_size} bytes")
    local human_avg=$(numfmt --to=iec "$avg_size" 2>/dev/null || echo "${avg_size} bytes")
    
    log_info "Total backup size: $human_total"
    log_info "Average backup size: $human_avg"
    
    # Check for suspiciously small backups (less than 50% of average)
    local min_size=$((avg_size / 2))
    local suspicious_count=0
    
    for i in "${!backup_files[@]}"; do
        local file="${backup_files[$i]}"
        local size="${backup_sizes[$i]}"
        local filename=$(basename "$file")
        
        if [ "$size" -lt "$min_size" ] && [ "$size" -gt 0 ]; then
            local human_size=$(numfmt --to=iec "$size" 2>/dev/null || echo "${size} bytes")
            
            # Extract backup datetime to check if it's a pre-blobs backup
            local backup_datetime=$(echo "$filename" | sed 's/plex-backup-\([0-9]\{8\}_[0-9]\{6\}\)\.tar\.gz/\1/')
            if [[ "$backup_datetime" =~ ^[0-9]{8}_[0-9]{6}$ ]] && [[ "$backup_datetime" < "20250526_144500" ]]; then
                log_info "Small backup (pre-blobs DB): $filename ($human_size)"
                log_info "  This backup predates the blobs database introduction, size is expected"
            else
                log_warning "Suspiciously small backup: $filename ($human_size)"
                suspicious_count=$((suspicious_count + 1))
            fi
        fi
    done
    
    if [ "$suspicious_count" -gt 0 ]; then
        log_warning "Found $suspicious_count backup(s) that may be incomplete"
        return 1
    else
        log_success "All backup sizes appear normal"
    fi
    
    return 0
}

# Check disk space
check_disk_space() {
    log_info "Checking disk space..."
    
    local backup_disk_usage=$(du -sh "$BACKUP_ROOT" | cut -f1)
    local available_space=$(df -h "$BACKUP_ROOT" | awk 'NR==2 {print $4}')
    local used_percentage=$(df "$BACKUP_ROOT" | awk 'NR==2 {print $5}' | sed 's/%//')
    
    log_info "Backup disk usage: $backup_disk_usage"
    log_info "Available space: $available_space"
    log_info "Disk usage: $used_percentage%"
    
    if [ "$used_percentage" -gt 90 ]; then
        log_error "Disk usage is above 90%"
        return 1
    elif [ "$used_percentage" -gt 80 ]; then
        log_warning "Disk usage is above 80%"
    else
        log_success "Disk usage is acceptable"
    fi
    
    return 0
}

# Generate backup report
generate_report() {
    log_info "Generating backup report..."
    
    local total_backups=0
    local valid_backups=0
    local total_errors=0
    
    # Header
    echo "==================================" >> "$REPORT_FILE"
    echo "Plex Backup Validation Report" >> "$REPORT_FILE"
    echo "Generated: $(date)" >> "$REPORT_FILE"
    echo "==================================" >> "$REPORT_FILE"
    
    # Use process substitution to avoid subshell variable scope issues
    while IFS= read -r backup_file; do
        total_backups=$((total_backups + 1))
        validate_backup "$backup_file"
        local backup_errors=$?
        
        if [ "$backup_errors" -eq 0 ]; then
            valid_backups=$((valid_backups + 1))
        else
            total_errors=$((total_errors + backup_errors))
        fi
    done < <(find "$BACKUP_ROOT" -maxdepth 1 -type f -name "plex-backup-*.tar.gz" | sort)
    
    # Summary
    echo >> "$REPORT_FILE"
    echo "Summary:" >> "$REPORT_FILE"
    echo "  Total backups: $total_backups" >> "$REPORT_FILE"
    echo "  Valid backups: $valid_backups" >> "$REPORT_FILE"
    echo "  Total errors: $total_errors" >> "$REPORT_FILE"
    
    log_success "Report generated: $REPORT_FILE"
}

# Fix common issues
fix_issues() {
    log_info "Attempting to fix common issues..."
    
    # Fix JSON log file
    if [ ! -f "$JSON_LOG_FILE" ] || ! jq empty "$JSON_LOG_FILE" 2>/dev/null; then
        log_info "Fixing JSON log file..."
        mkdir -p "$(dirname "$JSON_LOG_FILE")"
        echo "{}" > "$JSON_LOG_FILE"
        log_success "JSON log file created/fixed"
    fi
    
    # Create corrupted backups directory
    local corrupted_dir="$(dirname "$REPORT_FILE")/corrupted-backups"
    mkdir -p "$corrupted_dir"
    
    # Check for and move corrupted backup files using process substitution
    local corrupted_count=0
    while IFS= read -r backup_file; do
        if ! tar -tzf "$backup_file" >/dev/null 2>&1; then
            log_warning "Found corrupted backup: $(basename "$backup_file")"
            local backup_name=$(basename "$backup_file")
            local corrupted_backup="$corrupted_dir/$backup_name"
            
            if mv "$backup_file" "$corrupted_backup"; then
                log_success "Moved corrupted backup to: $corrupted_backup"
                corrupted_count=$((corrupted_count + 1))
            else
                log_error "Failed to move corrupted backup: $backup_name"
            fi
        fi
    done < <(find "$BACKUP_ROOT" -maxdepth 1 -type f -name "plex-backup-*.tar.gz" 2>/dev/null || true)
    
    if [ "$corrupted_count" -gt 0 ]; then
        log_info "Moved $corrupted_count corrupted backup(s) to $corrupted_dir"
    fi
    
    # Clean up any remaining dated directories from old backup structure
    find "$BACKUP_ROOT" -maxdepth 1 -type d -name "????????" -exec rm -rf {} \; 2>/dev/null || true
    
    # Fix permissions if needed
    if [ -d "$BACKUP_ROOT" ]; then
        chmod 755 "$BACKUP_ROOT" 2>/dev/null || log_warning "Could not fix backup root permissions"
        find "$BACKUP_ROOT" -type f -name "plex-backup-*.tar.gz" -exec chmod 644 {} \; 2>/dev/null || log_warning "Could not fix backup file permissions"
        log_success "Fixed backup permissions"
    fi
}

# Main function
main() {
    local fix_mode=false
    local report_mode=false
    local verbose_mode=false
    
    # Parse arguments
    while [[ $# -gt 0 ]]; do
        case $1 in
            --fix)
                fix_mode=true
                shift
                ;;
            --report)
                report_mode=true
                shift
                ;;
            --verbose|-v)
                verbose_mode=true
                shift
                ;;
            --help|-h)
                echo "Usage: $0 [OPTIONS]"
                echo "Validate Plex backup files and system health"
                echo ""
                echo "OPTIONS:"
                echo "  --fix       Attempt to fix common issues"
                echo "  --report    Generate detailed backup report"
                echo "  --verbose   Enable verbose output"
                echo "  --help      Show this help message"
                exit 0
                ;;
            *)
                echo "Usage: $0 [--fix] [--report] [--verbose]"
                echo "  --fix       Attempt to fix common issues"
                echo "  --report    Generate detailed backup report"
                echo "  --verbose   Enable verbose output"
                echo "Use --help for more information"
                exit 1
                ;;
        esac
    done
    
    log_info "Starting Plex backup validation..."
    
    # Check dependencies first
    if ! check_dependencies; then
        exit 1
    fi
    
    # Create logs directory if needed
    mkdir -p "$(dirname "$REPORT_FILE")"
    
    local overall_status=0
    local critical_errors=0
    local warnings=0
    
    # Fix issues if requested
    if [ "$fix_mode" = true ]; then
        fix_issues
    fi
    
    # Validate backup structure
    if ! validate_backup_structure; then
        critical_errors=$((critical_errors + 1))
    fi
    
    # Check backup freshness
    if ! check_backup_freshness; then
        local freshness_result=$?
        # Check if this is a "no backups found" error vs "old backup" warning
        local backup_count=$(find "$BACKUP_ROOT" -maxdepth 1 -type f -name "plex-backup-*.tar.gz" 2>/dev/null | wc -l)
        if [ "$backup_count" -eq 0 ]; then
            # No backups found - critical error
            critical_errors=$((critical_errors + 1))
        else
            # Old backup - warning only
            warnings=$((warnings + 1))
        fi
    fi
    
    # Validate JSON log
    if ! validate_json_log; then
        critical_errors=$((critical_errors + 1))
    fi
    
    # Check disk space
    if ! check_disk_space; then
        warnings=$((warnings + 1))
    fi
    
    # Check backup file sizes
    if [ "$verbose_mode" = true ] || [ "$report_mode" = true ]; then
        if ! check_backup_sizes; then
            warnings=$((warnings + 1))
        fi
    fi
    
    # Generate detailed report if requested
    if [ "$report_mode" = true ]; then
        generate_report
    fi
    
    # Final summary
    echo
    if [ "$critical_errors" -eq 0 ] && [ "$warnings" -eq 0 ]; then
        log_success "All validation checks passed"
        overall_status=0
    elif [ "$critical_errors" -eq 0 ]; then
        log_warning "Validation completed with $warnings warning(s) but no critical errors"
        log_info "System appears healthy despite warnings"
        overall_status=0
    else
        log_error "Validation failed with $critical_errors critical error(s) and $warnings warning(s)"
        overall_status=1
        echo
        echo "Consider running with --fix to attempt automatic repairs"
        echo "Use --report for a detailed backup analysis"
    fi
    
    exit $overall_status
}

main "$@"