#!/bin/bash
# Postfix Mail Summary Script (Hardened, Secure & Memory-Safe Version)

# ==============================================================================
# 0. RESOURCE LIMITS (Anti-DoS Protection)
# ==============================================================================
ulimit -t 15        # Max CPU time (seconds)
ulimit -v 500000    # Max virtual memory ~500MB
ulimit -f 102400    # Max file size created by script (100MB)

# ==============================================================================
# 1. LOCKFILE & PRE-FLIGHT CHECKS
# ==============================================================================
LOCKFILE="/tmp/postfix_summary.lock"
if [ -f "$LOCKFILE" ]; then
    PID=$(cat "$LOCKFILE" 2>/dev/null)
    if [ -n "$PID" ] && ps -p "$PID" > /dev/null 2>&1; then
        echo "Error: Another instance (PID $PID) is already running." >&2
        exit 1
    else
        rm -f "$LOCKFILE"
    fi
fi

find /tmp -name "postfix_log.*" -mmin +10 -user root -delete 2>/dev/null || true
TMP_DATA=$(mktemp /tmp/postfix_log.XXXXXX)

trap 'rm -f "$LOCKFILE" "$TMP_DATA" 2>/dev/null' EXIT

echo $$ > "$LOCKFILE"

set -euo pipefail
IFS=$'\n\t'

# ==============================================================================
# 2. HELP MESSAGE
# ==============================================================================
show_help() {
    echo "Usage: $0 [OPTIONS]"
    echo ""
    echo "Options:"
    echo "  -h, --help                Display this help message"
    echo "  -l, --list NUMBER         Show the last X records (default: 10, max: 1000)"
    echo "  -f, --from EMAIL/DOMAIN   Filter by SENDER (substring match)"
    echo "  -t, --to EMAIL/DOMAIN     Filter by RECIPIENT (substring match)"
    echo "  -i, --id QUEUE_ID         Search for a specific Queue ID"
    echo "  -d, --date \"MMM DD\"       Filter by date (e.g., \"Mar 27\")"
    exit 0
}

# ==============================================================================
# 3. INITIALIZATION & ARGUMENT PARSING
# ==============================================================================
export USE_COLOR=0
[[ -t 1 ]] && USE_COLOR=1

LIMIT=10
MAX_LIMIT=1000
FROM_FILTER=""
TO_FILTER=""
ID_FILTER=""
DATE_FILTER=""
MAX_INPUT_LEN=100

while [[ "$#" -gt 0 ]]; do
    case $1 in
        -h|--help) show_help ;;
        -l|--list) 
            if [[ "$2" =~ ^[0-9]+$ ]]; then LIMIT="$2"; else LIMIT=10; fi
            (( LIMIT > MAX_LIMIT )) && LIMIT=$MAX_LIMIT
            shift ;;
        -f|--from) FROM_FILTER="${2:0:$MAX_INPUT_LEN}"; shift ;;
        -t|--to)   TO_FILTER="${2:0:$MAX_INPUT_LEN}"; shift ;;
        -i|--id)   ID_FILTER="${2:0:$MAX_INPUT_LEN}"; shift ;;
        -d|--date) DATE_FILTER="${2:0:$MAX_INPUT_LEN}"; shift ;;
        *) echo "Unknown parameter: $1. Use -h for help." >&2; exit 1 ;;
    esac
    shift
done

# ==============================================================================
# 4. LOG FILE COLLECTION
# ==============================================================================
LOG_FILES=()
if sort -z </dev/null >/dev/null 2>&1; then
    while IFS= read -r -d '' file; do
        LOG_FILES+=("$file")
    done < <(find /var/log -maxdepth 1 -name 'maillog*' -type f -print0 | sort -z)
else
    while IFS= read -r -d '' file; do
        LOG_FILES+=("$file")
    done < <(find /var/log -maxdepth 1 -name 'maillog*' -type f -print0 | sort)
fi

if [ ${#LOG_FILES[@]} -eq 0 ]; then
    echo "Error: No Postfix logs found in /var/log/." >&2
    exit 1
fi

# ==============================================================================
# 5. OPTIMIZED LOG READING
# ==============================================================================
read_logs() {
if [[ -z "$DATE_FILTER" ]]; then
        DATE_FILTER=$(date '+%b %e') 
    fi

    for log in "${LOG_FILES[@]}"; do
        if [[ ! -r "$log" ]]; then continue; fi
        
        if [[ "$log" =~ \.gz$ ]]; then
            # zcat už sám o sebe číta celý komprimovaný súbor
            zcat -f -- "$log" | awk -v d_filt="$DATE_FILTER" 'substr($0,1,length(d_filt)) == d_filt'
        else
            # ZMENA: Namiesto tail použijeme cat, aby sme prešli celý súbor
            cat -- "$log" | awk -v d_filt="$DATE_FILTER" 'substr($0,1,length(d_filt)) == d_filt'
        fi
    done
}

# ==============================================================================
# 6. SECURE LOG ANALYSIS (With Memory Garbage Collection)
# ==============================================================================
read_logs | awk -v f_filt="$FROM_FILTER" -v t_filt="$TO_FILTER" -v i_filt="$ID_FILTER" -v d_filt="$DATE_FILTER" '
function shorten(addr, max_len) {
    if (length(addr) <= max_len) return addr;
    if (index(addr, "@") > 0) {
        split(addr, p, "@");
        user = p[1]; domain = "@" p[2];
        if (length(domain) > (max_len - 10)) return ".." substr(domain, length(domain)-(max_len-5));
        user_limit = max_len - length(domain) - 2;
        if (user_limit < 3) user_limit = 3;
        return substr(user, 1, user_limit) ".." domain;
    }
    return substr(addr, 1, max_len-3) "...";
}

# Garbage collector to prevent RAM exhaustion from abandoned Queue IDs
function gc() {
    if (num_ids > 2000) {
        for (idx in client_ip) {
            delete client_ip[idx]; delete from[idx];
            num_ids--;
            if (num_ids < 1000) break;
        }
    }
}

BEGIN {
    blue="\033[1;34m"; bold="\033[1m"; reset="\033[0m"; green="\033[1;32m"; red="\033[1;31m"; yellow="\033[1;33m"; cyan="\033[0;36m"; gray="\033[0;90m"
    if (ENVIRON["USE_COLOR"] != "1") {
        blue=""; bold=""; reset=""; green=""; red=""; yellow=""; cyan=""; gray="";
    }
    printf "%-16s %-12s %-16s %-36s %-31s %-12s %s\n", "DATE-TIME", "ID", "CLIENT_IP", "SENDER", "RECIPIENT", "STATUS", "REASON"
    num_ids = 0;
}
{
    # Basic validation: Skip lines that are too short or suspicious
    if (length($0) < 20 || length($0) > 1000) next;

    full_time = $1 "-" $2 "-" $3;
    qid = "";
    if ($6 ~ /^[A-F0-9]+:$/) { qid = $6; gsub(/:/, "", qid); }
    else if ($5 ~ /^[A-F0-9]+:$/) { qid = $5; gsub(/:/, "", qid); }
    
    if (qid == "" && index($0, "NOQUEUE") == 0) next;

    # Capture Client IP
    if (index($0, "client=") > 0) {
        match($0, /\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\]/);
        if (RLENGTH > 0) {
            client_ip[qid] = substr($0, RSTART+1, RLENGTH-2);
            num_ids++;
            gc();
        }
    }
    # Capture Sender
    if (index($0, "from=<") > 0) {
        match($0, /from=<[^>]+>/);
        if (RLENGTH > 0) from[qid] = substr($0, RSTART+6, RLENGTH-7);
    }

    # Final Transaction Processing
    if (index($0, "to=<") > 0 && index($0, "status=") > 0) {
        s_ip = (client_ip[qid] != "") ? client_ip[qid] : "local";
        if (s_ip == "127.0.0.1") {
            delete client_ip[qid]; delete from[qid]; num_ids--;
            next;
        }

        s_from = (from[qid] != "") ? from[qid] : "-";
        match($0, /to=<[^>]+>/); 
        s_to = (RLENGTH > 0) ? substr($0, RSTART+4, RLENGTH-5) : "-";
        
        match($0, /status=[a-z]+/); 
        s_stat = (RLENGTH > 0) ? substr($0, RSTART+7, RLENGTH-7) : "unknown";
        
        s_reason = "-"; r_col = reset; scol = reset;

        if (s_stat == "sent") { scol = green; s_reason = "OK"; r_col = cyan; }
        else if (s_stat == "deferred") { scol = yellow; r_col = yellow; }
        else if (s_stat == "bounced") { scol = red; r_col = red; }

        if (s_stat != "sent" && match($0, /\([^)]*\)/)) {
            s_reason = substr($0, RSTART+1, RLENGTH-2);
            if (length(s_reason) > 25) s_reason = substr(s_reason, 1, 22) "..";
        }

        # Apply Filters
        if ((f_filt == "" || index(s_from, f_filt) > 0) && 
            (t_filt == "" || index(s_to, t_filt) > 0) && 
            (i_filt == "" || index(qid, i_filt) > 0)) {
            printf "%s%-16s %s%-12s%s %s%-16s%s %-36s %-31s %s%-12s%s %s[%s]%s\n", 
                reset, full_time, blue, qid, reset, gray, s_ip, reset, shorten(s_from, 35), shorten(s_to, 30), scol, s_stat, reset, r_col, s_reason, reset;
        }
        delete client_ip[qid]; delete from[qid]; num_ids--;
    }
    
    # Handle Blocked Connections (NOQUEUE)
    if (index($0, "NOQUEUE: reject:") > 0) {
        match($0, /from=<[^>]+>/); f = (RLENGTH > 0) ? substr($0, RSTART+6, RLENGTH-7) : "-";
        match($0, /to=<[^>]+>/);   t = (RLENGTH > 0) ? substr($0, RSTART+4, RLENGTH-5) : "-";
        n_ip = "unknown";
        if (match($0, /\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\]/)) n_ip = substr($0, RSTART+1, RLENGTH-2);
        
        if ((f_filt == "" || index(f, f_filt) > 0) && 
            (t_filt == "" || index(t, t_filt) > 0) && 
            (i_filt == "" || i_filt == "NOQUEUE")) {
            printf "%s%-16s %s%-12s%s %s%-16s%s %-36s %-31s %s%-12s%s %s[Blocked]%s\n", 
                reset, full_time, red, "NOQUEUE", reset, gray, n_ip, reset, shorten(f, 35), shorten(t, 30), red, "REJECT", reset, yellow, "Policy", reset;
        }
    }
}' > "$TMP_DATA"

# ==============================================================================
# 7. FINAL OUTPUT
# ==============================================================================
head -n 1 "$TMP_DATA"
sed '1d' "$TMP_DATA" | tail -n "$LIMIT"