#!/usr/bin/env bash
# =============================================================================
# Script Name : db_backuper.sh
# Description : Backup PostgreSQL database called by cron or manually.
# Usage       : ./db_backuper
# Author      : syr4ok (Andrii Syrovatko)
# Version     : 2.1.3r
# =============================================================================

# Stop script on pipeline errors
set -o pipefail

PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

# --- LOADING CONFIGURATION ---
DATE_NOW=$(date +%y%m%d)
CONFIG_FILE="$(dirname "$0")/db_backuper.conf"
if [[ -f "$CONFIG_FILE" ]]; then
    # shellcheck source=/dev/null
    source "$CONFIG_FILE"
else
    echo "Error: Configuration file not found. Create db_backuper.conf from example."
    exit 1
fi

# --- DEPENDENCY CHECK ---
# Check critical tool (if not present - exit)
if ! command -v "${PSQL_COMMAND}" &> /dev/null; then
    PSQL_COMMAND=$(which pg_basebackup 2>/dev/null)
    if [ -z "$PSQL_COMMAND" ]; then
        echo "❌ Critical Error: pg_basebackup not found! Backup impossible."
        exit 1
    fi
fi
# Checking optional tools (Curl (for Telegram) / Mail)
HAS_CURL=true
HAS_MAIL=true
command -v curl &> /dev/null || HAS_CURL=false
command -v mail &> /dev/null || HAS_MAIL=false

# --- Main functions ---
log_divider() {
    local LABEL=$1
    echo "----------------------- $LABEL $(date +%Y/%m/%d-%H:%M) $LABEL -----------------------"
}

send_tg() {
    if [ "$HAS_CURL" = true ]; then
        /usr/bin/curl -s -X POST "https://api.telegram.org/bot${TG_BOT_ID}/sendMessage" -d chat_id=${TG_CHAT_ID} -d text="[${S_HOSTNAME}]: $1"
    else
        echo "⚠️ Warning: Telegram report skipped (curl not installed)." | tee -a "${CACHE_FILE}"
    fi
}

send_report() {
    local STATUS=$1
    local EMOJI="💾"
    [ "$STATUS" == "ERROR" ] && EMOJI="❌"

    log_divider "END" >> "${CACHE_FILE}"
    if [ "$HAS_MAIL" = true ]; then
        local SUBJECT
        SUBJECT="[${S_HOSTNAME}] ${EMOJI} ${STATUS} DB Backup Info - $(date +%Y/%m/%d-%H:%M)"
        cat "${CACHE_FILE}" | mail -s "$SUBJECT" "$MAIL_SENDER" "$MAIL_RECEIVER"
    else
        echo "⚠️ Warning: Email report skipped (mailutils not installed)." | tee -a "${CACHE_FILE}"
    fi
}


# --- BLOCKING THE SCRIPT (only one working process per time)---
exec 200>"$LOCK_FILE"
if ! flock -n 200; then
    msg="❌ The script is already running in another process. Exit!"
    echo "$msg" | tee -a "${CACHE_FILE}"
    send_tg "$msg"
    send_report "ERROR"
    exit 1
fi

# --- START ---

# 1. Preparing the log file
[ ! -f "${CACHE_FILE}" ] && touch "${CACHE_FILE}" && chmod 660 "${CACHE_FILE}"
log_divider "START" > "${CACHE_FILE}"

# 2. Checking and mounting NFS (only if IS_LOCAL_BACKUP=false)
DB_DIR="$MNT_POINT/psql_db_$DATE_NOW"
TMP_MSG="locally"
if [ "$IS_LOCAL_BACKUP" = false ]; then
    TMP_MSG="on NFS"
    if ! command -v mount.nfs &> /dev/null; then
        msg="❌ Critical Error: nfs-common (mount.nfs) is not installed! Remote backup impossible."
        echo "$msg" | tee -a "${CACHE_FILE}"
        send_tg "$msg"
        send_report "ERROR"
        exit 1
    fi
    if ! mountpoint -q "$MNT_POINT"; then
        echo "Attempting to mount NFS..." >> "${CACHE_FILE}"
        if ! mount -t nfs "${NFS_SERVER_IP}:${NFS_SERVER_DIR}" "$MNT_POINT" -o soft,timeo=30,retrans=2; then
            msg="❌ NFS Mount Failed! Server ${NFS_SERVER_IP} unreachable."
            echo "$msg" | tee -a "${CACHE_FILE}"
            send_tg "$msg"
            send_report "ERROR"
            exit 1
        fi
    fi
fi

# 3. Check for duplicate directory
if [ -d "${DB_DIR}" ]; then
    msg="⚠️ DB backup stopped. Today's dir ($DB_DIR) already exists!"
    echo "$msg" | tee -a "${CACHE_FILE}"
    send_tg "$msg"
    send_report "ERROR"
    exit 1
fi

# 4. Creating a directory
if [ "$DEBUG" -eq 1 ]; then
    echo "DEBUG: [DRY RUN] Skipping directory creation: ${DB_DIR}" >> "${CACHE_FILE}"
else
    if ! mkdir -p "${DB_DIR}"; then
        msg="❌ Failed to create directory ${DB_DIR} ${TMP_MSG}."
        echo "$msg" | tee -a "${CACHE_FILE}"
        send_tg "$msg"
        send_report "ERROR"
        exit 1
    fi
    chown postgres:postgres "${DB_DIR}"
fi

# 5. Starting a backup process
BACKUP_SUCCESS=false
{
    [ "$DEBUG" -eq 1 ] && echo "--- DEBUG MODE ON (DRY RUN) ---"
    echo "Backup DB STARTED at $(date +%Y/%m/%d-%H:%M)"
} >> "${CACHE_FILE}"

if [ "$DEBUG" -eq 1 ]; then
    echo "DEBUG: Skipping real pg_basebackup command..." >> "${CACHE_FILE}"
    BACKUP_SUCCESS=true # True - to read old files.
else
    if [ "$EXTENDED_BACK_STATUS" = true ]; then
        EXT_STATUS_MSG='-P'
    else
        EXT_STATUS_MSG=''
    fi

    echo -e "Using command for DB dump:\ncd /tmp/ && sudo -u ${PSQL_USER} ${PSQL_COMMAND} -p ${PSQL_PORT} -D ${DB_DIR} --checkpoint=${PSQL_CHECKPOINT} -Ft -z ${EXT_STATUS_MSG} 2>&1" | tee -a "${CACHE_FILE}"

    if cd /tmp/ && sudo -u "${PSQL_USER}" "${PSQL_COMMAND}" -p "${PSQL_PORT}" -D "${DB_DIR}" --checkpoint="${PSQL_CHECKPOINT}" -Ft -z ${EXT_STATUS_MSG} 2>&1 | tee -a "${CACHE_FILE}"; then
        # Checking whether the file was actually created (additional security measure)
        if [ -d "${DB_DIR}" ]; then
            BACKUP_SUCCESS=true
            sync
            DUMP_SIZE=$(du -sh "${DB_DIR}" 2>/dev/null | cut -f1)
            echo -e "Files synced and compressed!\nDB dump size: ${DUMP_SIZE}" | tee -a "${CACHE_FILE}"
        fi
    fi
fi

# 6. Cleaning up old backups
if [ "$BACKUP_SUCCESS" = true ]; then
    echo "Cleaning old backups ${TMP_MSG} (Retention: ${RETENTION_DAYS} days)..." | tee -a "${CACHE_FILE}"

    mapfile -t OLD_BACKUPS < <(find "${MNT_POINT}" -mindepth 1 -maxdepth 1 -name "psql_db*" -mtime +"${RETENTION_DAYS}" -print)

    if [ ${#OLD_BACKUPS[@]} -gt 0 ]; then
        echo "Found ${#OLD_BACKUPS[@]} old backup(s) for deletion:" | tee -a "${CACHE_FILE}"
        for dir in "${OLD_BACKUPS[@]}"; do
            if [ "$DEBUG" -eq 1 ]; then
                echo "DEBUG: [DRY RUN] Would delete: $dir" | tee -a "${CACHE_FILE}"
            else
                echo "Deleting: $dir" | tee -a "${CACHE_FILE}"
                rm -rfv "$dir" | tee -a "${CACHE_FILE}" 2>&1
            fi
        done
        echo "Cleanup finished." | tee -a "${CACHE_FILE}"
    else
        echo "No old backups found older than ${RETENTION_DAYS} days." | tee -a "${CACHE_FILE}"
    fi

    sync
    send_report "SUCCESS"
else
    msg="❌ Backup process failed!"
    echo "$msg" | tee -a "${CACHE_FILE}"
    send_tg "$msg"
    send_report "ERROR"
    exit 1
fi


# 7. Complete and exit
exit 0