path: root/dicore3/command/src/main/java/io/dico/dicore/command/IContextFilter.java

package io.dico.dicore.command;

import io.dico.dicore.exceptions.checkedfunctions.CheckedConsumer;
import io.dico.dicore.exceptions.checkedfunctions.CheckedRunnable;
import org.bukkit.command.CommandSender;

import java.util.List;
import java.util.Objects;

public interface IContextFilter extends Comparable<IContextFilter> {

    /**
     * Filter the given context by this filter's criteria.
     * If the context does not match the criteria, an exception is thrown describing the problem.
     *
     * @param context the context to match
     * @throws CommandException if it doesn't match
     */
    void filterContext(ExecutionContext context) throws CommandException;

    /**
     * Filter an execution context for a direct or indirect sub command of the command that registered this filter.
     *
     * @param subContext the context for the execution
     * @param path       the path traversed from the command that registered this filter to the executed command
     */
    default void filterSubContext(ExecutionContext subContext, String... path) throws CommandException {
        filterContext(subContext);
    }

    /**
     * Get the priority of this context filter.
     * The priorities determine the order in which a command's context filters are executed.
     *
     * @return the priority
     */
    Priority getPriority();

    default boolean allowsContext(ExecutionContext context) {
        try {
            filterContext(context);
            return true;
        } catch (CommandException ex) {
            return false;
        }
    }

    /**
     * Used to sort filters in execution order. That is, filters are ordered by {@link #getPriority()}
     *
     * @param o compared filter
     * @return comparison value
     */
    @Override
    default int compareTo(IContextFilter o) {
        return getPriority().compareTo(o.getPriority());
    }

    default boolean isInheritable() {
        return false;
    }

    default IContextFilter inherit(String... components) {
        if (!isInheritable()) {
            throw new IllegalStateException("This IContextFilter cannot be inherited");
        }

        return this;
    }

    /**
     * IContextFilter priorities. Executes from top to bottom.
     */
    enum Priority {
        /**
         * This priority should have checks on the sender type.
         * Any filters on this priority are tested before permissions are.
         * This is the highest priority.
         */
        VERY_EARLY, // sender type check

        /**
         * This priority is specific to permissions.
         */
        PERMISSION,

        /**
         * Early priority. Post permissions, pre parameter-parsing.
         */
        EARLY,

        /**
         * Normal priority. Post permissions, pre parameter-parsing.
         */
        NORMAL,

        /**
         * Late priority. Post permissions, pre parameter-parsing.
         */
        LATE,

        /**
         * Very late priority. Post permissions, pre parameter-parsing.
         */
        VERY_LATE,

        /**
         * Post parameters priority. Post permissions, post parameter-parsing.
         * This is the lowest priority.
         */
        POST_PARAMETERS;

        /**
         * Get the context filter that inherits context filters from the parent of the same priority.
         * If this filter is also present at the parent, it will do the same for the parent's parent, and so on.
         *
         * @return the inheritor
         */
        public IContextFilter getInheritor() {
            return inheritor;
        }

        private static String[] addParent(String[] path, String parent) {
            String[] out = new String[path.length + 1];
            System.arraycopy(path, 0, out, 0, path.length);
            out[0] = parent;
            return out;
        }

        final IContextFilter inheritor = new IContextFilter() {
            @Override
            public void filterContext(ExecutionContext context) throws CommandException {
                ICommandAddress address = context.getAddress();

                String[] traversedPath = new String[0];
                do {
                    traversedPath = addParent(traversedPath, address.getMainKey());
                    address = address.getParent();

                    if (address != null && address.hasCommand()) {
                        boolean doBreak = true;

                        Command command = address.getCommand();
                        List<IContextFilter> contextFilterList = command.getContextFilters();
                        for (IContextFilter filter : contextFilterList) {
                            if (filter.getPriority() == Priority.this) {
                                if (filter == this) {
                                    // do the same for next parent
                                    // this method is necessary to keep traversedPath information
                                    doBreak = false;
                                } else {
                                    filter.filterSubContext(context, traversedPath);
                                }
                            }
                        }

                        if (doBreak) {
                            break;
                        }
                    }
                } while (address != null);
            }

            @Override
            public Priority getPriority() {
                return Priority.this;
            }
        };

    }

    /**
     * Ensures that only {@link org.bukkit.entity.Player} type senders can execute the command.
     */
    IContextFilter PLAYER_ONLY = filterSender(Priority.VERY_EARLY, Validate::isPlayer);

    /**
     * Ensures that only {@link org.bukkit.command.ConsoleCommandSender} type senders can execute the command.
     */
    IContextFilter CONSOLE_ONLY = filterSender(Priority.VERY_EARLY, Validate::isConsole);

    /**
     * This filter is not working as intended.
     * <p>
     * There is supposed to be a permission filter that takes a base, and appends the command's address to the base, and checks that permission.
     */
    IContextFilter INHERIT_PERMISSIONS = Priority.PERMISSION.getInheritor();

    static IContextFilter fromCheckedRunnable(Priority priority, CheckedRunnable<? extends CommandException> runnable) {
        return new IContextFilter() {
            @Override
            public void filterContext(ExecutionContext context) throws CommandException {
                runnable.checkedRun();
            }

            @Override
            public Priority getPriority() {
                return priority;
            }
        };
    }

    static IContextFilter filterSender(Priority priority, CheckedConsumer<? super CommandSender, ? extends CommandException> consumer) {
        return new IContextFilter() {
            @Override
            public void filterContext(ExecutionContext context) throws CommandException {
                consumer.checkedAccept(context.getSender());
            }

            @Override
            public Priority getPriority() {
                return priority;
            }
        };
    }

    static IContextFilter permission(String permission) {
        Objects.requireNonNull(permission);
        return filterSender(Priority.PERMISSION, sender -> Validate.isAuthorized(sender, permission));
    }

    static IContextFilter permission(String permission, String failMessage) {
        Objects.requireNonNull(permission);
        Objects.requireNonNull(failMessage);
        return filterSender(Priority.PERMISSION, sender -> Validate.isAuthorized(sender, permission, failMessage));
    }

    /**
     * Produce an inheritable permission context filter.
     * A permission component is an element in {@code permission.split("\\.")}
     *
     * @param permission              The permission that is required for the command that this is directly assigned to
     * @param componentInsertionIndex the index where any sub-components are inserted. -1 for "at the end".
     * @param failMessage             the message to send if the permission is not met
     * @return the context filter
     * @throws IllegalArgumentException if componentInsertionIndex is out of range
     */
    static IContextFilter inheritablePermission(String permission, int componentInsertionIndex, String failMessage) {
        Objects.requireNonNull(permission);
        Objects.requireNonNull(failMessage);
        if (componentInsertionIndex > permission.split("\\.").length || componentInsertionIndex < -1) {
            throw new IllegalArgumentException("componentInsertionIndex out of range");
        }


        return new IContextFilter() {
            private String getInheritedPermission(String[] components) {
                int insertedAmount = components.length;
                String[] currentComponents = permission.split("\\.");
                int currentAmount = currentComponents.length;
                String[] targetArray = new String[currentAmount + insertedAmount];

                int insertionIndex;
                //int newInsertionIndex;
                if (componentInsertionIndex == -1) {
                    insertionIndex = currentAmount;
                    //newInsertionIndex = -1;
                } else {
                    insertionIndex = componentInsertionIndex;
                    //newInsertionIndex = insertionIndex + insertedAmount;
                }

                // copy the current components up to insertionIndex
                System.arraycopy(currentComponents, 0, targetArray, 0, insertionIndex);
                // copy the new components into the array at insertionIndex
                System.arraycopy(components, 0, targetArray, insertionIndex, insertedAmount);
                // copy the current components from insertionIndex + inserted amount
                System.arraycopy(currentComponents, insertionIndex, targetArray, insertionIndex + insertedAmount, currentAmount - insertionIndex);

                return String.join(".", targetArray);
            }

            @Override
            public void filterContext(ExecutionContext context) throws CommandException {
                Validate.isAuthorized(context.getSender(), permission, failMessage);
            }

            @Override
            public void filterSubContext(ExecutionContext subContext, String... path) throws CommandException {
                Validate.isAuthorized(subContext.getSender(), getInheritedPermission(path), failMessage);
            }

            @Override
            public Priority getPriority() {
                return Priority.PERMISSION;
            }

            @Override
            public boolean isInheritable() {
                return true;
            }

            @Override
            public IContextFilter inherit(String... components) {
                int insertedAmount = components.length;
                String[] currentComponents = permission.split("\\.");
                int currentAmount = currentComponents.length;
                String[] targetArray = new String[currentAmount + insertedAmount];

                int insertionIndex;
                int newInsertionIndex;
                if (componentInsertionIndex == -1) {
                    insertionIndex = currentAmount;
                    newInsertionIndex = -1;
                } else {
                    insertionIndex = componentInsertionIndex;
                    newInsertionIndex = insertionIndex + insertedAmount;
                }

                // copy the current components up to insertionIndex
                System.arraycopy(currentComponents, 0, targetArray, 0, insertionIndex);
                // copy the new components into the array at insertionIndex
                System.arraycopy(components, 0, targetArray, insertionIndex, insertedAmount);
                // copy the current components from insertionIndex + inserted amount
                System.arraycopy(currentComponents, insertionIndex, targetArray, insertionIndex + insertedAmount, currentAmount - insertionIndex);

                return inheritablePermission(String.join(".", targetArray), newInsertionIndex, failMessage);
            }
        };
    }

}