#!/bin/bash

################################################################################
# Fast 500 Error Tracker
################################################################################
# Purpose: ONLY track 500 errors - find them fast and show WHY
# No menus, no options - just find 500s and diagnose the root cause
################################################################################

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
source "$SCRIPT_DIR/lib/common-functions.sh"

# Ensure color variables are set
DIM='\033[2m'
BOLD='\033[1m'

print_banner "Fast 500 Error Tracker"

echo ""
echo "Scanning for 500 errors and diagnosing root causes..."
echo ""

# Ask for time range
echo -e "${CYAN}How far back to scan?${NC}"
echo "  1) Last 24 hours (default)"
echo "  2) Last 7 days"
echo "  3) Last 30 days"
echo ""
read -p "Select option [1]: " time_choice
time_choice=${time_choice:-1}

case $time_choice in
    1) HOURS_TO_SCAN=24 ;;
    2) HOURS_TO_SCAN=168 ;;
    3) HOURS_TO_SCAN=720 ;;
    *) HOURS_TO_SCAN=24 ;;
esac

echo ""
echo "→ Scanning last $HOURS_TO_SCAN hours of access logs..."
echo ""

# Temporary files
TEMP_DIR="/tmp/500-tracker-$$"
mkdir -p "$TEMP_DIR"
trap "rm -rf $TEMP_DIR" EXIT

ERRORS_500="$TEMP_DIR/errors_500.txt"
ERROR_DETAILS="$TEMP_DIR/error_details.txt"

# Configuration
DOMLOGS_DIR="/var/log/apache2/domlogs"

# Get cutoff time
cutoff_time=$(date -d "$HOURS_TO_SCAN hours ago" +%s 2>/dev/null || echo "0")

declare -A domain_count
declare -A domain_user
total_500s=0

# Scan all domain access logs for 500 errors
for log in "$DOMLOGS_DIR"/*; do
    [ -f "$log" ] || continue
    [[ "$log" =~ (bytes_log|offset|error_log|ftpxferlog|-ssl_log)$ ]] && continue

    domain="${log##*/}"
    domain="${domain%%-*}"

    # Skip non-domain system logs (proxy, localhost, etc.)
    [[ "$domain" =~ ^(proxy|localhost|default|cpanel|webmail|whm|cpcalendars|cpcontacts|webdisk)$ ]] && continue
    
    # Find cPanel user for this domain
    user=$(grep -l "DNS.*$domain" /var/cpanel/users/* 2>/dev/null | head -1 | xargs basename 2>/dev/null)
    [ -z "$user" ] && user="unknown"
    
    domain_user["$domain"]="$user"
    
    # Scan for 500 errors in this log
    while IFS= read -r line; do
        # Check for 500 status code
        if [[ "$line" =~ '"'[[:space:]](5[0-9]{2})[[:space:]] ]]; then
            status="${BASH_REMATCH[1]}"
            
            # Time filtering
            if [ "$cutoff_time" != "0" ]; then
                if [[ "$line" =~ \[([0-9]{2}/[A-Z][a-z]{2}/[0-9]{4}:[0-9]{2}:[0-9]{2}:[0-9]{2}) ]]; then
                    log_date="${BASH_REMATCH[1]}"
                    log_time=$(date -d "${log_date/:/ }" +%s 2>/dev/null || echo "0")
                    [ "$log_time" != "0" ] && [ "$log_time" -lt "$cutoff_time" ] && continue
                fi
            fi
            
            # Parse log line
            read -r ip _ _ timestamp _ request _ _ <<< "$line"
            
            # Extract URL
            if [[ "$request" =~ '"'[A-Z]+[[:space:]]([^[:space:]]+) ]]; then
                url="${BASH_REMATCH[1]:0:80}"
            else
                url="/"
            fi
            
            # Extract timestamp
            if [[ "$line" =~ \[([^]]+)\] ]]; then
                timestamp="${BASH_REMATCH[1]}"
            else
                timestamp="unknown"
            fi
            
            ((domain_count["$domain"]++))
            ((total_500s++))
            
            # Save for analysis
            echo "$domain|$user|$status|$url|$timestamp|$ip" >> "$ERRORS_500"
        fi
    done < <(tail -n 100000 "$log" 2>/dev/null)
done

if [ "$total_500s" -eq 0 ]; then
    echo ""
    echo -e "${GREEN}━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━${NC}"
    echo -e "${GREEN} ✓ NO 500 ERRORS FOUND IN LAST $HOURS_TO_SCAN HOURS!${NC}"
    echo -e "${GREEN}━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━${NC}"
    echo ""
    exit 0
fi

echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
echo " 🔥 500 ERRORS DETECTED: $total_500s errors"
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
echo ""

echo -e "${RED}${BOLD}TOP AFFECTED DOMAINS:${NC}"
echo ""

# Sort and display top domains
for domain in "${!domain_count[@]}"; do
    echo "${domain_count[$domain]} $domain ${domain_user[$domain]}"
done | sort -rn | head -10 | while read count domain user; do
    printf "  ${RED}●${NC} %-40s ${BOLD}%4d errors${NC}  (user: %s)\n" "$domain" "$count" "$user"
done

echo ""
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
echo " 🔍 DIAGNOSING ROOT CAUSES"
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
echo ""

# For each affected domain, check the actual PHP error logs
declare -A diagnosed_causes
declare -A cause_examples

while IFS='|' read -r domain user status url timestamp ip; do
    [ -z "$domain" ] && continue

    # Find PHP error log - check multiple locations
    error_log=""
    if [ "$user" != "unknown" ]; then
        # Try multiple possible locations
        for potential_log in \
            "/home/$user/public_html/error_log" \
            "/home/$user/logs/error_log" \
            "/home/$user/error_log" \
            "/var/log/apache2/domlogs/$domain-error_log" \
            "/usr/local/apache/domlogs/$domain"; do

            if [ -f "$potential_log" ]; then
                error_log="$potential_log"
                break
            fi
        done
    fi

    # Check if error log exists and has recent errors
    if [ -n "$error_log" ] && [ -f "$error_log" ]; then
        # Look for errors around the same time as the 500
        recent_error=$(tail -500 "$error_log" | grep -E "Fatal error|Parse error|syntax error|memory.*exhausted|database|MySQL|Permission denied" | tail -1)

        if [ -n "$recent_error" ]; then
            # Determine cause
            cause="UNKNOWN"
            if [[ "$recent_error" =~ (memory.*exhausted|Allowed memory size) ]]; then
                cause="PHP_MEMORY_EXHAUSTED"
                cause_examples["$cause"]="$domain: $recent_error"
            elif [[ "$recent_error" =~ (Fatal error|PHP Fatal error) ]]; then
                if [[ "$recent_error" =~ (undefined function|Call to undefined function) ]]; then
                    cause="MISSING_PHP_FUNCTION"
                    cause_examples["$cause"]="$domain: $recent_error"
                else
                    cause="PHP_FATAL_ERROR"
                    cause_examples["$cause"]="$domain: $recent_error"
                fi
            elif [[ "$recent_error" =~ (Parse error|syntax error) ]]; then
                cause="PHP_SYNTAX_ERROR"
                cause_examples["$cause"]="$domain: $recent_error"
            elif [[ "$recent_error" =~ (database|MySQL|Can\'t connect) ]]; then
                cause="DATABASE_CONNECTION"
                cause_examples["$cause"]="$domain: $recent_error"
            fi
            
            ((diagnosed_causes["$cause"]++))
        else
            ((diagnosed_causes["NO_PHP_ERROR_LOGGED"]++))
        fi
    else
        # No error log found - likely .htaccess issue
        # Check if .htaccess exists and might have issues
        if [ "$user" != "unknown" ] && [ -f "/home/$user/public_html/.htaccess" ]; then
            # Check for common .htaccess syntax errors
            htaccess_check=$(grep -E "RewriteEngine|RewriteRule|RewriteCond|php_value|php_flag" "/home/$user/public_html/.htaccess" 2>/dev/null)
            if [ -n "$htaccess_check" ]; then
                ((diagnosed_causes["HTACCESS_LIKELY"]++))
                cause_examples["HTACCESS_LIKELY"]="$domain (user: $user) - has .htaccess with rewrite rules, check syntax"
            else
                ((diagnosed_causes["NO_ERROR_LOG_FILE"]++))
                cause_examples["NO_ERROR_LOG_FILE"]="$domain (user: $user) - checked multiple locations, no error_log found"
            fi
        else
            ((diagnosed_causes["NO_ERROR_LOG_FILE"]++))
            cause_examples["NO_ERROR_LOG_FILE"]="$domain (user: $user) - checked multiple locations, no error_log found"
        fi
    fi
done < "$ERRORS_500"

# Display diagnosed causes
echo -e "${CYAN}${BOLD}ROOT CAUSES IDENTIFIED:${NC}"
echo ""

for cause in "${!diagnosed_causes[@]}"; do
    count="${diagnosed_causes[$cause]}"
    echo "$count|$cause"
done | sort -rn | while IFS='|' read count cause; do
    clean_cause=$(echo "$cause" | tr '_' ' ')
    
    case "$cause" in
        PHP_MEMORY_EXHAUSTED)
            echo -e "${RED}🔥 $clean_cause${NC} - $count occurrences"
            echo "   ${YELLOW}Fix:${NC} Increase memory_limit in /home/USER/public_html/.user.ini"
            echo "   ${YELLOW}Set:${NC} memory_limit = 512M"
            ;;
        PHP_FATAL_ERROR)
            echo -e "${RED}⚠️  $clean_cause${NC} - $count occurrences"
            echo "   ${YELLOW}Fix:${NC} Review recent code/plugin changes"
            ;;
        PHP_SYNTAX_ERROR)
            echo -e "${RED}📝 $clean_cause${NC} - $count occurrences"
            echo "   ${YELLOW}Fix:${NC} Check for PHP syntax errors in recent file edits"
            ;;
        MISSING_PHP_FUNCTION)
            echo -e "${RED}📦 $clean_cause${NC} - $count occurrences"
            echo "   ${YELLOW}Fix:${NC} Install missing PHP extension (check error for which one)"
            ;;
        DATABASE_CONNECTION)
            echo -e "${RED}🗄️  $clean_cause${NC} - $count occurrences"
            echo "   ${YELLOW}Fix:${NC} Check database credentials or MySQL service"
            ;;
        HTACCESS_LIKELY)
            echo -e "${RED}⚙️  .HTACCESS SYNTAX ERROR (LIKELY)${NC} - $count occurrences"
            echo "   ${YELLOW}Fix:${NC} Check .htaccess file for syntax errors"
            echo "   ${YELLOW}Test:${NC} Temporarily rename .htaccess to .htaccess.bak and test"
            echo "   ${YELLOW}Common issues:${NC} Invalid RewriteRule, bad php_value directives"
            ;;
        NO_ERROR_LOG_FILE)
            echo -e "${YELLOW}📄 $clean_cause${NC} - $count occurrences"
            echo "   ${YELLOW}Note:${NC} Checked multiple error_log locations - none found"
            echo "   ${YELLOW}Check:${NC} May need to enable PHP error logging"
            ;;
        NO_PHP_ERROR_LOGGED)
            echo -e "${YELLOW}❓ $clean_cause${NC} - $count occurrences"
            echo "   ${YELLOW}Note:${NC} 500 error but no PHP error in log - likely .htaccess or Apache config"
            ;;
        *)
            echo -e "${INFO_COLOR}• $clean_cause${NC} - $count occurrences"
            ;;
    esac
    
    # Show example if we have one
    if [ -n "${cause_examples[$cause]}" ]; then
        example="${cause_examples[$cause]}"
        echo "   ${DIM}Example: ${example:0:120}...${NC}"
    fi
    echo ""
done

echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
echo " 📋 DETAILED 500 ERROR LIST"
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
echo ""

# Show most frequent URLs getting 500s
echo "Most Frequent 500 Error URLs:"
echo ""
cut -d'|' -f1,4 "$ERRORS_500" | sort | uniq -c | sort -rn | head -15 | while read count domain_url; do
    domain=$(echo "$domain_url" | cut -d'|' -f1)
    url=$(echo "$domain_url" | cut -d'|' -f2)
    user="${domain_user[$domain]}"
    printf "  ${RED}%4d×${NC} %s%s ${DIM}(user: %s)${NC}\n" "$count" "$domain" "$url" "$user"
done

echo ""
echo "Full error list saved to: $ERRORS_500"
echo ""

press_enter