#!/bin/bash
# =============================================================================
# SAP HANA Monitoring Library - Shared Functions
# =============================================================================

# Logging function with script name prefix
# Usage: log_message "SCRIPT_NAME" "message"
log_message() {
    local script_name="$1"
    local message="$2"
    local timestamp=$(date "+%Y-%m-%d %H:%M:%S")
    echo "[${timestamp}] [${script_name}] ${message}" | tee -a "${LOG_FILE}"
}

# Acquire lock for script execution
# Usage: acquire_lock "SCRIPT_NAME"
# Returns: 0 on success, 1 on failure (already running)
acquire_lock() {
    local script_name="$1"
    local lock_file="${LOCK_DIR}/hana_${script_name}.lock"
    
    if [ -e "$lock_file" ]; then
        log_message "$script_name" "Script is already running. Exiting."
        return 1
    fi
    
    touch "$lock_file"
    echo "$lock_file"
    return 0
}

# Release lock
# Usage: release_lock "LOCK_FILE"
release_lock() {
    local lock_file="$1"
    if [ -n "$lock_file" ] && [ -f "$lock_file" ]; then
        rm -f "$lock_file"
    fi
}

# Get state value
# Usage: get_state "KEY"
get_state() {
    local key="$1"
    if [ -f "${STATE_DIR}/${key}.state" ]; then
        cat "${STATE_DIR}/${key}.state"
    else
        echo ""
    fi
}

# Set state value
# Usage: set_state "KEY" "VALUE"
set_state() {
    local key="$1"
    local value="$2"
    echo "$value" > "${STATE_DIR}/${key}.state"
}

# Send notification if state changed
# Usage: send_notification_if_changed "SCRIPT_NAME" "ALERT_KEY" "TITLE_PREFIX" "MESSAGE" "IS_ALERT" "CURRENT_VALUE"
send_notification_if_changed() {
    local script_name="$1"
    local alert_key="$2"
    local title_prefix="$3"
    local current_message="$4"
    local is_alert_condition="$5"
    local current_value="$6"
    local hostname=$(hostname)
    
    local previous_value=$(get_state "$alert_key")
    
    if [ "$current_value" != "$previous_value" ]; then
        local full_title=""
        local full_message=""
        
        if [ "$is_alert_condition" == "true" ]; then
            full_title="${title_prefix} Alert"
            full_message="🚨 Critical: ${current_message}"
            log_message "$script_name" "ALERT: ${full_message}"
        else
            if [ -n "$previous_value" ] && [ "$previous_value" != "OK" ]; then
                full_title="${title_prefix} Resolved"
                full_message="✅ Resolved: ${current_message}"
                log_message "$script_name" "RESOLVED: ${full_message}"
            else
                set_state "$alert_key" "$current_value"
                return
            fi
        fi
        
        local final_message="[${COMPANY_NAME} | ${hostname}] ${full_message}"
        
        if [ -n "$NTFY_TOKEN" ] && [ -n "$NTFY_TOPIC_URL" ]; then
            curl -H "Authorization: Bearer ${NTFY_TOKEN}" -H "Title: ${full_title}" -d "${final_message}" "${NTFY_TOPIC_URL}" > /dev/null 2>&1
            log_message "$script_name" "Notification sent: ${full_title}"
        else
            log_message "$script_name" "Ntfy not configured, skipping notification"
        fi
        
        set_state "$alert_key" "$current_value"
    fi
}

# Run command as HANA user using su
# Usage: run_as_hana_user "COMMAND"
run_as_hana_user() {
    local command="$1"
    su - "$HANA_USER" -c "$command"
}

# Get disk usage percentage for a directory
# Usage: get_disk_usage_percentage "/path/to/dir"
# Returns: Usage percentage as integer (without % sign)
get_disk_usage_percentage() {
    local dir="$1"
    if [ ! -d "$dir" ]; then
        echo "0"
        return
    fi
    df "$dir" 2>/dev/null | awk 'NR==2 {gsub(/%/,"",$5); print $5}'
}

# Get mount point for a directory
# Usage: get_mount_point "/path/to/dir"
# Returns: Mount point path
get_mount_point() {
    local dir="$1"
    df "$dir" 2>/dev/null | awk 'NR==2 {print $NF}'
}

# Get available disk space in KB for a directory
# Usage: get_available_space_kb "/path/to/dir"
# Returns: Available space in KB
get_available_space_kb() {
    local dir="$1"
    df -k "$dir" 2>/dev/null | awk 'NR==2 {print $4}'
}

# Find log directories on the same mount point
# Usage: find_log_dirs_on_mount "mount_point"
# Returns: Space-separated list of log directories
find_log_dirs_on_mount() {
    local mount_point="$1"
    local result=""
    
    for log_entry in "${LOG_DIRS_FOR_CLEANUP[@]}"; do
        local entry_mount="${log_entry%%:*}"
        local log_dir="${log_entry#*:}"
        
        if [ "$entry_mount" == "$mount_point" ] && [ -d "$log_dir" ]; then
            if [ -n "$result" ]; then
                result="$result $log_dir"
            else
                result="$log_dir"
            fi
        fi
    done
    
    echo "$result"
}

# Clean old log files in a directory
# Usage: clean_log_files "/path/to/log/dir" "max_age_days"
# Returns: Number of files deleted and space freed
clean_log_files() {
    local log_dir="$1"
    local max_age_days="${2:-7}"
    local files_deleted=0
    local space_freed=0
    
    if [ ! -d "$log_dir" ]; then
        log_message "CLEANUP" "Log directory '$log_dir' not found. Skipping."
        echo "0:0"
        return
    fi
    
    # Find and delete old log files
    while IFS= read -r -d '' file; do
        if [ -f "$file" ]; then
            local file_size=$(stat -c%s "$file" 2>/dev/null || echo "0")
            rm -f "$file" 2>/dev/null && {
                files_deleted=$((files_deleted + 1))
                space_freed=$((space_freed + file_size))
            }
        fi
    done < <(find "$log_dir" -type f -mtime +$max_age_days -print0 2>/dev/null)
    
    # Also clean empty directories
    find "$log_dir" -type d -empty -delete 2>/dev/null
    
    log_message "CLEANUP" "Deleted $files_deleted files from '$log_dir', freed $((space_freed / 1024)) KB"
    echo "${files_deleted}:${space_freed}"
}

# Automatic disk cleanup function
# Usage: auto_cleanup "mount_point" "target_free_percentage"
# Returns: 0 if cleanup successful, 1 if failed or not needed
auto_cleanup() {
    local mount_point="$1"
    local target_free_percentage="${2:-5}"
    
    if [ "$AUTO_CLEANUP_ENABLED" != "true" ]; then
        log_message "CLEANUP" "Auto-cleanup is disabled. Skipping."
        return 1
    fi
    
    local log_dirs=$(find_log_dirs_on_mount "$mount_point")
    
    if [ -z "$log_dirs" ]; then
        log_message "CLEANUP" "No log directories configured for mount point '$mount_point'. Skipping cleanup."
        return 1
    fi
    
    log_message "CLEANUP" "Starting auto-cleanup for mount point '$mount_point'. Log dirs: $log_dirs"
    
    local total_freed=0
    local total_files=0
    
    for log_dir in $log_dirs; do
        local result=$(clean_log_files "$log_dir" "$MAX_LOG_FILE_AGE_DAYS")
        local files="${result%%:*}"
        local freed="${result#*:}"
        total_files=$((total_files + files))
        total_freed=$((total_freed + freed))
    done
    
    log_message "CLEANUP" "Cleanup complete. Total files deleted: $total_files, Total space freed: $((total_freed / 1024)) KB"
    
    if [ $total_freed -gt 0 ]; then
        return 0
    else
        return 1
    fi
}

# Check disk space and perform auto-cleanup if needed
# Usage: check_and_cleanup_disk "directory" "threshold"
# Returns: 0 if OK or cleanup successful, 1 if critical and cleanup failed
check_and_cleanup_disk() {
    local dir="$1"
    local threshold="${2:-85}"
    
    local usage=$(get_disk_usage_percentage "$dir")
    local mount_point=$(get_mount_point "$dir")
    
    if [ -z "$usage" ] || [ "$usage" -eq 0 ]; then
        log_message "CLEANUP" "Could not determine disk usage for '$dir'. Skipping."
        return 1
    fi
    
    if [ "$usage" -gt "$threshold" ]; then
        log_message "CLEANUP" "Disk usage ${usage}% exceeds threshold ${threshold}% for '$dir'. Attempting cleanup..."
        
        if auto_cleanup "$mount_point" "$MIN_FREE_SPACE_AFTER_CLEANUP"; then
            local new_usage=$(get_disk_usage_percentage "$dir")
            log_message "CLEANUP" "After cleanup, disk usage is ${new_usage}%"
            
            if [ "$new_usage" -le "$threshold" ]; then
                return 0
            else
                log_message "CLEANUP" "Cleanup completed but usage ${new_usage}% still above threshold"
                return 0
            fi
        else
            log_message "CLEANUP" "Cleanup failed or no files to clean for '$dir'"
            return 1
        fi
    fi
    
    return 0
}