package org.ovirt.engine.core.bll.snapshots;

import javax.inject.Inject;
import javax.inject.Singleton;

import org.ovirt.engine.core.bll.ValidationResult;
import org.ovirt.engine.core.common.businessentities.Snapshot;
import org.ovirt.engine.core.common.businessentities.Snapshot.SnapshotStatus;
import org.ovirt.engine.core.common.businessentities.Snapshot.SnapshotType;
import org.ovirt.engine.core.common.errors.EngineMessage;
import org.ovirt.engine.core.compat.Guid;
import org.ovirt.engine.core.dao.SnapshotDao;

/**
 * Validator that is used to test if there are snapshots in progress, etc.
 */
@Singleton
public class SnapshotsValidator {

    @Inject
    private SnapshotDao snapshotDao;

    /**
     * Return whether the VM is during a snapshot operation (running currently on the VM).
     *
     * @param vmId
     *            The VM to check for.
     * @return Is the VM during a snapshot operation or not.
     */
    public ValidationResult vmNotDuringSnapshot(Guid vmId) {
        return vmNotInStatus(vmId, SnapshotStatus.LOCKED, EngineMessage.ACTION_TYPE_FAILED_VM_IS_DURING_SNAPSHOT);
    }

    /**
     * Return whether the VM is in preview (running currently on a snapshot other than the active one).
     *
     * @param vmId
     *            The VM to check for.
     * @return Is the VM is preview or not.
     */
    public ValidationResult vmNotInPreview(Guid vmId) {
        return vmNotInStatus(vmId, SnapshotStatus.IN_PREVIEW, EngineMessage.ACTION_TYPE_FAILED_VM_IN_PREVIEW);
    }

    /**
     * Return whether the VM has a snapshot in the given status.
     *
     * @param vmId
     *            The VM to check for.
     * @param status
     *            The status of a snapshot to look for
     * @param msg
     *            The validation error to return if the snapshot exists
     *
     * @return <code>true</code> if the VM dons't habe a snapshot in the given status.
     */
    private ValidationResult vmNotInStatus(Guid vmId, SnapshotStatus status, EngineMessage msg) {
        if (snapshotDao.exists(vmId, status)) {
            return new ValidationResult(msg);
        }

        return ValidationResult.VALID;
    }

    /**
     * Check if the given snapshot id exists for the given VM in the DB.
     *
     * @param vmId
     *            ID of VM to check for.
     * @param snapshotId
     *            Snapshot ID to check.
     * @return Snapshot exists or not.
     */
    public ValidationResult snapshotExists(Guid vmId, Guid snapshotId) {
        return createSnapshotExistsResult(snapshotDao.exists(vmId, snapshotId));
    }

    /**
     * Check if the given snapshot is null, then it means it doesn't exist.
     *
     * @param snapshot
     *            Snapshot to check.
     * @return Snapshot exists (not null) or not.
     */
    public ValidationResult snapshotExists(Snapshot snapshot) {
        return createSnapshotExistsResult(snapshot != null);
    }

    /**
     * Checks if the given snapshot's type is regular.
     */
    public ValidationResult isRegularSnapshot(Snapshot snapshot) {
        if (SnapshotType.REGULAR != snapshot.getType()) {
            return new ValidationResult(EngineMessage.ACTION_TYPE_FAILED_VM_SNAPSHOT_TYPE_NOT_REGULAR);
        }

        return ValidationResult.VALID;
    }

    /**
     * Checks if the given snapshot's VM configuration in broken.
     */
    public ValidationResult snapshotVmConfigurationBroken(Snapshot snapshot, String vmName) {
        return !snapshot.isVmConfigurationBroken()
                ? ValidationResult.VALID
                : new ValidationResult(EngineMessage.ACTION_TYPE_FAILED_VM_SNAPSHOT_HAS_NO_CONFIGURATION,
                String.format("$VmName %1$s", vmName),
                String.format("$SnapshotName %1$s", snapshot.getDescription()));
    }

    /**
     * Create result that indicates if snapshot exists or not.
     *
     * @param snapshotExists
     *            Does the snapshot exist?
     * @return Result that either contains the suitable error or not.
     */
    private ValidationResult createSnapshotExistsResult(boolean snapshotExists) {
        return snapshotExists
                ? ValidationResult.VALID
                : new ValidationResult(EngineMessage.ACTION_TYPE_FAILED_VM_SNAPSHOT_DOES_NOT_EXIST);
    }
}