#!/bin/bash
set -euo pipefail

#######################################
# Date format for logging.
#######################################
LOG_DATE_FORMAT="%Y-%m-%dT%T"

#######################################
# Log a message with a timestamp.
# Arguments:
#   Message to log.
#######################################
log() {
    echo "$(date +"$LOG_DATE_FORMAT") - $*"
}

#######################################
# Determine operation mode from the environment only.
# Valid values: "backup" or "restore".
# Default to "backup" if not provided.
#######################################
OPERATION_MODE="${OPERATION_MODE:-backup}"

#######################################
# Determine backup mode from the environment only.
# Valid values: "directory", "postgres", or "s3".
# Default to "directory" if not provided.
#######################################
BACKUP_MODE="${BACKUP_MODE:-directory}"

#######################################
# Check for required external commands.
#######################################
REQUIRED_CMDS=(restic curl jq)
if [ "$BACKUP_MODE" = "postgres" ]; then
    if [ "$OPERATION_MODE" = "backup" ]; then
        REQUIRED_CMDS+=(pg_dump)
    elif [ "$OPERATION_MODE" = "restore" ]; then
        REQUIRED_CMDS+=(psql)
    fi
elif [ "$BACKUP_MODE" = "s3" ]; then
    REQUIRED_CMDS+=(mc)
fi

for cmd in "${REQUIRED_CMDS[@]}"; do
    if ! command -v "$cmd" &>/dev/null; then
        log "Error: Required command '$cmd' is not installed."
        exit 1
    fi
done

#######################################
# Validate common required environment variables.
#######################################
# Gotify notification settings (optional).
# Set ENABLE_GOTIFY to "true" to enable notifications, any other value or unset disables them.
ENABLE_GOTIFY="${ENABLE_GOTIFY:-true}"

if [ "$ENABLE_GOTIFY" = "true" ]; then
    : "${GOTIFYHOST:?Environment variable GOTIFYHOST is not set (required when ENABLE_GOTIFY=true)}"
    : "${GOTIFYTOKEN:?Environment variable GOTIFYTOKEN is not set (required when ENABLE_GOTIFY=true)}"
    : "${GOTIFYTOPIC:?Environment variable GOTIFYTOPIC is not set (required when ENABLE_GOTIFY=true)}"
else
    log "Gotify notifications disabled. Backup status will be logged to console only."
fi

# Restic encryption password.
: "${RESTIC_PASSWORD:?Environment variable RESTIC_PASSWORD is not set}"

# Use the repository URI directly from the environment.
# Example: export RESTIC_REPOSITORY="rest:http://your-rest-server:8000/backup"
: "${RESTIC_REPOSITORY:?Environment variable RESTIC_REPOSITORY is not set}"

#######################################
# Validate operation mode.
#######################################
case "$OPERATION_MODE" in
    backup|restore)
        ;;
    *)
        echo "Error: Unknown operation mode '$OPERATION_MODE'. Valid modes are 'backup' and 'restore'." >&2
        exit 1
        ;;
esac

#######################################
# Validate mode-specific environment variables.
#######################################
case "$BACKUP_MODE" in
    directory)
        if [ "$OPERATION_MODE" = "backup" ]; then
            : "${SOURCEDIR:?Environment variable SOURCEDIR is not set (required for directory backup mode)}"
        elif [ "$OPERATION_MODE" = "restore" ]; then
            : "${RESTOREDIR:?Environment variable RESTOREDIR is not set (required for directory restore mode)}"
        fi
        ;;
    postgres)
        : "${PGHOST:?Environment variable PGHOST is not set (required for PostgreSQL mode)}"
        : "${PGDATABASE:?Environment variable PGDATABASE is not set (required for PostgreSQL mode)}"
        : "${PGUSER:?Environment variable PGUSER is not set (required for PostgreSQL mode)}"
        # Optional: default PGPORT to 5432.
        : "${PGPORT:=5432}"
        if [ -z "${PGPASSWORD:-}" ]; then
            if [ "$OPERATION_MODE" = "backup" ]; then
                echo "Warning: Environment variable PGPASSWORD is not set. pg_dump may fail if authentication is required."
            elif [ "$OPERATION_MODE" = "restore" ]; then
                echo "Warning: Environment variable PGPASSWORD is not set. psql may fail if authentication is required."
            fi
        fi
        ;;
    s3)
        : "${S3_BUCKET:?Environment variable S3_BUCKET is not set (required for S3 mode)}"
        : "${S3_ENDPOINT:?Environment variable S3_ENDPOINT is not set (required for S3 mode)}"
        : "${MINIO_ACCESS_KEY:?Environment variable MINIO_ACCESS_KEY is not set (required for S3 mode)}"
        : "${MINIO_SECRET_KEY:?Environment variable MINIO_SECRET_KEY is not set (required for S3 mode)}"
        # Optional: S3 path prefix
        : "${S3_PREFIX:=}"
        ;;
    *)
        echo "Error: Unknown backup mode '$BACKUP_MODE'. Valid modes are 'directory', 'postgres', and 's3'." >&2
        exit 1
        ;;
esac

#######################################
# Build the Gotify URL (only if Gotify is enabled).
#######################################
if [ "$ENABLE_GOTIFY" = "true" ]; then
    GOTIFYURL="${GOTIFYHOST}/message?token=${GOTIFYTOKEN}"
fi

#######################################
# Send a notification via Gotify.
# Arguments:
#   message: The message to send.
#######################################
send_notification() {
    local message="$1"
    
    # Only send notification if Gotify is enabled
    if [ "$ENABLE_GOTIFY" != "true" ]; then
        log "$message"
        return 0
    fi
    
    if ! curl -s -X POST "$GOTIFYURL" -F "title=${GOTIFYTOPIC}" -F "message=${message}" >/dev/null; then
        log "Warning: Failed to send notification with message: ${message}"
    fi
}

#######################################
# Run the backup using restic.
# The --no-cache flag disables local caching.
# Arguments:
#   $1 - The source directory to back up.
#######################################
run_restic_backup() {
    local source_dir="$1"
    cd "${source_dir}"
    log "Starting backup of '${source_dir}' to repository ${RESTIC_REPOSITORY}"
    # Capture both stdout and stderr in a variable
    backup_output=$(restic -r "${RESTIC_REPOSITORY}" backup --no-cache --json --verbose . 2>&1)
    # Optionally, also print the output to the console:
    echo "$backup_output"
    # Parse the JSON lines output for the summary message
    summary=$(echo "$backup_output" | jq -r 'select(.message_type=="summary") | "Snapshot " + (.snapshot_id // "none") + ": " + "files new: " + (.files_new|tostring) + ", files changed: " + (.files_changed|tostring) + ", data added: " + (.data_added|tostring) + " bytes in " + (.total_duration|tostring) + " sec"')
    # Check exit code of restic backup (assuming restic exits non-zero on error)
    if [ $? -eq 0 ]; then
        msg="Backup successful. $summary"
        log "$msg"
        send_notification "$msg"
    else
        exit_code=$?
        msg="Backup failed with error code ${exit_code}. $backup_output"
        log "$msg"
        send_notification "$msg"
        exit "$exit_code"
    fi
}


#######################################
# Backup a directory (regular mode).
#######################################
backup_directory() {
    run_restic_backup "${SOURCEDIR}"
}

#######################################
# Backup a PostgreSQL database.
# Dumps the database to a temporary directory and then backs it up.
#######################################
backup_postgres() {
    log "Starting PostgreSQL backup for database '${PGDATABASE}' on host '${PGHOST}'"
    
    # Create a temporary directory for the database dump.
    TEMP_BACKUP_DIR=$(mktemp -d)
    log "Created temporary directory: ${TEMP_BACKUP_DIR}"

    local dump_file="${TEMP_BACKUP_DIR}/dump.sql"
    log "Dumping PostgreSQL database to ${dump_file}..."
    if pg_dump -h "${PGHOST}" -p "${PGPORT}" -U "${PGUSER}" ${PG_DUMP_ARGS:-} "${PGDATABASE}" > "${dump_file}"; then
        log "Database dump created successfully."
    else
        local exit_code=$?
        local msg="PostgreSQL dump failed with error code ${exit_code}"
        log "$msg"
        send_notification "$msg"
        exit "$exit_code"
    fi

    # Back up the directory containing the dump.
    run_restic_backup "${TEMP_BACKUP_DIR}"
}

#######################################
# Run the restore using restic.
# Arguments:
#   $1 - The target directory to restore to.
#   $2 - Optional snapshot ID to restore (defaults to latest).
#######################################
run_restic_restore() {
    local target_dir="$1"
    local snapshot_id="$2"
    
    log "Starting restore from repository ${RESTIC_REPOSITORY} to '${target_dir}'"
    log "Using snapshot: ${snapshot_id}"
    
    # Create target directory if it doesn't exist
    mkdir -p "${target_dir}"
    
    # Capture both stdout and stderr in a variable
    restore_output=$(restic -r "${RESTIC_REPOSITORY}" restore "${snapshot_id}" --target "${target_dir}" --no-cache --json --verbose 2>&1)
    # Optionally, also print the output to the console:
    echo "$restore_output"
    
    # Parse the JSON lines output for the summary message
    summary=$(echo "$restore_output" | jq -r 'select(.message_type=="summary") | "Restore completed: " + (.files_restored|tostring) + " files restored, " + (.bytes_restored|tostring) + " bytes in " + (.total_duration|tostring) + " sec"' 2>/dev/null || echo "Restore completed")
    
    # Check exit code of restic restore
    if [ $? -eq 0 ]; then
        msg="Restore successful. $summary"
        log "$msg"
        send_notification "$msg"
    else
        exit_code=$?
        msg="Restore failed with error code ${exit_code}. $restore_output"
        log "$msg"
        send_notification "$msg"
        exit "$exit_code"
    fi
}

#######################################
# Restore a directory (regular mode).
#######################################
restore_directory() {
    local snapshot_id="${RESTORE_SNAPSHOT_ID:-latest}"
    run_restic_restore "${RESTOREDIR}" "${snapshot_id}"
}

#######################################
# Restore a PostgreSQL database.
# Restores the database dump from the backup and applies it to the database.
#######################################
restore_postgres() {
    local snapshot_id="${RESTORE_SNAPSHOT_ID:-latest}"
    log "Starting PostgreSQL restore for database '${PGDATABASE}' on host '${PGHOST}'"
    
    # Create a temporary directory for the restore.
    TEMP_RESTORE_DIR=$(mktemp -d)
    log "Created temporary directory: ${TEMP_RESTORE_DIR}"

    # Restore the backup to the temporary directory
    run_restic_restore "${TEMP_RESTORE_DIR}" "${snapshot_id}"
    
    local dump_file="${TEMP_RESTORE_DIR}/dump.sql"
    if [ ! -f "${dump_file}" ]; then
        local msg="PostgreSQL restore failed. Database dump file not found at ${dump_file}"
        log "$msg"
        send_notification "$msg"
        exit 1
    fi
    
    log "Restoring PostgreSQL database from ${dump_file}..."
    if psql -h "${PGHOST}" -p "${PGPORT}" -U "${PGUSER}" -d "${PGDATABASE}" ${PSQL_ARGS:-} < "${dump_file}"; then
        local msg="PostgreSQL database restored successfully"
        log "$msg"
        send_notification "$msg"
    else
        local exit_code=$?
        local msg="PostgreSQL restore failed with error code ${exit_code}"
        log "$msg"
        send_notification "$msg"
        exit "$exit_code"
    fi
}

#######################################
# Backup an S3 bucket.
# Syncs the S3 bucket to a temporary directory and then backs it up.
#######################################
backup_s3() {
    log "Starting S3 backup for bucket '${S3_BUCKET}' at endpoint '${S3_ENDPOINT}'"
    
    # Create a temporary directory for the S3 sync.
    TEMP_BACKUP_DIR=$(mktemp -d)
    log "Created temporary directory: ${TEMP_BACKUP_DIR}"

    # Configure MinIO Client alias
    local alias_name="backupsidecar"
    if ! mc alias set "${alias_name}" "${S3_ENDPOINT}" "${MINIO_ACCESS_KEY}" "${MINIO_SECRET_KEY}"; then
        local msg="Failed to configure MinIO client alias"
        log "$msg"
        send_notification "$msg"
        exit 1
    fi

    # Build S3 path
    local s3_path="${alias_name}/${S3_BUCKET}"
    if [ -n "${S3_PREFIX}" ]; then
        s3_path="${s3_path}/${S3_PREFIX}"
    fi

    log "Syncing S3 bucket from ${s3_path} to ${TEMP_BACKUP_DIR}..."
    if mc mirror "${s3_path}" "${TEMP_BACKUP_DIR}" --remove; then
        log "S3 sync completed successfully."
    else
        local exit_code=$?
        local msg="S3 sync failed with error code ${exit_code}"
        log "$msg"
        send_notification "$msg"
        exit "$exit_code"
    fi

    # Back up the directory containing the S3 content.
    run_restic_backup "${TEMP_BACKUP_DIR}"
}

#######################################
# Restore an S3 bucket.
# Restores the S3 content from the backup and syncs it back to S3.
#######################################
restore_s3() {
    local snapshot_id="${RESTORE_SNAPSHOT_ID:-latest}"
    log "Starting S3 restore for bucket '${S3_BUCKET}' at endpoint '${S3_ENDPOINT}'"
    
    # Create a temporary directory for the restore.
    TEMP_RESTORE_DIR=$(mktemp -d)
    log "Created temporary directory: ${TEMP_RESTORE_DIR}"

    # Restore the backup to the temporary directory
    run_restic_restore "${TEMP_RESTORE_DIR}" "${snapshot_id}"

    # Configure MinIO Client alias
    local alias_name="backupsidecar"
    if ! mc alias set "${alias_name}" "${S3_ENDPOINT}" "${MINIO_ACCESS_KEY}" "${MINIO_SECRET_KEY}"; then
        local msg="Failed to configure MinIO client alias"
        log "$msg"
        send_notification "$msg"
        exit 1
    fi

    # Build S3 path
    local s3_path="${alias_name}/${S3_BUCKET}"
    if [ -n "${S3_PREFIX}" ]; then
        s3_path="${s3_path}/${S3_PREFIX}"
    fi

    log "Syncing restored content from ${TEMP_RESTORE_DIR} to ${s3_path}..."
    if mc mirror "${TEMP_RESTORE_DIR}" "${s3_path}" --remove; then
        local msg="S3 restore completed successfully"
        log "$msg"
        send_notification "$msg"
    else
        local exit_code=$?
        local msg="S3 restore failed with error code ${exit_code}"
        log "$msg"
        send_notification "$msg"
        exit "$exit_code"
    fi
}

#######################################
# Cleanup temporary resources.
#######################################
cleanup() {
    if [ -n "${TEMP_BACKUP_DIR:-}" ] && [ -d "${TEMP_BACKUP_DIR}" ]; then
        rm -rf "${TEMP_BACKUP_DIR}"
        log "Removed temporary directory ${TEMP_BACKUP_DIR}"
    fi
    if [ -n "${TEMP_RESTORE_DIR:-}" ] && [ -d "${TEMP_RESTORE_DIR}" ]; then
        rm -rf "${TEMP_RESTORE_DIR}"
        log "Removed temporary directory ${TEMP_RESTORE_DIR}"
    fi
}
trap cleanup EXIT

#######################################
# Main routine.
#######################################
main() {
    case "$OPERATION_MODE" in
        backup)
            case "$BACKUP_MODE" in
                directory)
                    backup_directory
                    ;;
                postgres)
                    backup_postgres
                    ;;
                s3)
                    backup_s3
                    ;;
            esac
            ;;
        restore)
            case "$BACKUP_MODE" in
                directory)
                    restore_directory
                    ;;
                postgres)
                    restore_postgres
                    ;;
                s3)
                    restore_s3
                    ;;
            esac
            ;;
    esac
}

# Trap termination signals to log and exit cleanly.
trap 'log "Script interrupted. Exiting."; exit 1' SIGINT SIGTERM

main