package io.dico.dicore.command;

import io.dico.dicore.command.chat.IChatHandler;
import io.dico.dicore.command.parameter.type.IParameterTypeSelector;
import io.dico.dicore.command.parameter.type.MapBasedParameterTypeSelector;
import io.dico.dicore.command.parameter.type.ParameterType;
import io.dico.dicore.command.predef.HelpCommand;
import io.dico.dicore.command.predef.PredefinedCommand;
import io.dico.dicore.command.predef.SyntaxCommand;
import io.dico.dicore.command.registration.reflect.ReflectiveRegistration;

import java.util.HashSet;
import java.util.Objects;
import java.util.function.Consumer;

/**
 * Mimic of WorldEdit's CommandGraph
 */
public final class CommandBuilder {
    private final RootCommandAddress root;
    private ModifiableCommandAddress cur;
    private IParameterTypeSelector selector;

    /**
     * Instantiate a new CommandBuilder with a new command root system
     * Commands registered to this command builder might interfere with
     * commands registered to other commands builders or by other plugins.
     */
    public CommandBuilder() {
        this(new RootCommandAddress());
    }

    /**
     * Instantiate a new CommandBuilder with a specified root address.
     * If the root address is identical to that of another command builder,
     * they will modify the same tree.
     *
     * @param root the root address
     */
    public CommandBuilder(RootCommandAddress root) {
        this.root = Objects.requireNonNull(root);
        this.cur = root;
        this.selector = new MapBasedParameterTypeSelector(true);
    }

    /**
     * Add a sub command at the current address
     * The current address can be inspected using {@link #getAddress()}
     *
     * @param name    the name of the command
     * @param command the command executor
     * @param aliases any aliases
     * @return this
     */
    public CommandBuilder addSubCommand(String name, Command command, String... aliases) {
        ChildCommandAddress address = new ChildCommandAddress(command);
        address.addNameAndAliases(name, aliases);
        return addSubCommand(address);
    }

    /**
     * Add a subcommand as an address at the current address
     * The result of this call is the same as
     * {@code addSubCommand(address.getMainKey(), address.getCommand(), address.getNames().sublist(1).toArray(new String[0]))}
     *
     * @param address the address
     * @return this
     * @throws IllegalArgumentException if {@code address.isRoot()}
     */
    public CommandBuilder addSubCommand(ICommandAddress address) {
        cur.addChild(address);
        return this;
    }

    /**
     * Search the given class for any (static) methods using command annotations
     * The class gets a localized parameter type selector if it defines parameter types.
     * Any commands found are registered as sub commands to the current address.
     *
     * @param clazz the clazz
     * @return this
     * @throws IllegalArgumentException if an exception occurs while parsing the methods of this class
     * @see #registerCommands(Class, Object)
     */
    public CommandBuilder registerCommands(Class<?> clazz) {
        return registerCommands(clazz, null);
    }

    /**
     * Search the given object's class for methods using command annotations.
     * If the object is null, only static methods are checked. Otherwise, instance methods are also checked.
     * The class gets a localized parameter type selector if it defines parameter types.
     * Any commands found are registered as sub commands to the current address.
     *
     * @param object the object
     * @return this
     * @throws IllegalArgumentException if an exception occurs while parsing the methods of this class
     * @see #registerCommands(Class, Object)
     */
    public CommandBuilder registerCommands(Object object) {
        return registerCommands(object.getClass(), object);
    }

    /**
     * Search the given class for methods using command annotations.
     * The class gets a localized parameter type selector if it defines parameter types.
     * Any commands found are registered as sub commands to the current address.
     * The instance is used to invoke non-static methods.
     *
     * @param clazz    the class
     * @param instance the instance, null if only static methods
     * @return this
     * @throws IllegalArgumentException if instance is not null and it's not an instance of the class
     * @throws IllegalArgumentException if another exception occurs while parsing the methods of this class
     */
    public CommandBuilder registerCommands(Class<?> clazz, Object instance) {
        try {
            ReflectiveRegistration.parseCommandGroup(cur, selector, clazz, instance);
            return this;
        } catch (Exception ex) {
            throw new IllegalArgumentException(ex);
        }
    }

    /**
     * register the {@link HelpCommand} as a sub command at the current address
     *
     * @return this
     */
    public CommandBuilder registerHelpCommand() {
        HelpCommand.registerAsChild(cur);
        return this;
    }

    /**
     * register the {@link SyntaxCommand} as a sub command a the current address
     *
     * @return this
     */
    public CommandBuilder registerSyntaxCommand() {
        SyntaxCommand.registerAsChild(cur);
        return this;
    }

    /**
     * Generate the predefined commands.
     * These are presets.
     * Examples include {@code help} and {@code syntax}.
     * <p>
     * Predefined commands can be registered through {@link PredefinedCommand#registerPredefinedCommandGenerator(String, Consumer)}
     *
     * @param commands the commands
     * @return this
     */
    public CommandBuilder generatePredefinedCommands(String... commands) {
        ReflectiveRegistration.generateCommands(cur, commands);
        return this;
    }

    /**
     * Unregister any childs present at the given keys.
     * <p>
     * This method can be used to remove unwanted keys, that might have been added
     * outside of your control. For example, because you didn't want all commands
     * registered by {@link #registerCommands(Class, Object)}, or because you didn't
     * want the help command registered by {@link #group(String, String...)}
     *
     * @param removeAliases true if any aliases of the children present at the keys should be removed
     * @param keys          a varargs array containing the keys
     * @return this
     * @throws IllegalArgumentException if keys array is empty
     */
    public CommandBuilder unregisterCommands(boolean removeAliases, String... keys) {
        cur.removeChildren(removeAliases, keys);
        return this;
    }

    /**
     * Jump to the sub-address with the given name as main key.
     * If an address with the exact name as main key exists,
     * that address becomes the current address.
     * <p>
     * Otherwise, a new addresses is registered with the name and aliases.
     * New addresses registered by this command have a HelpCommand added by default.
     * <p>
     * After this call, any registered commands are registered as a sub command
     * to the new address. To restore the previous state, a call to {@link #parent()}
     * should be made.
     * <p>
     * If the address is the target of a command, it will provide information about its sub commands
     * using the HelpCommand.
     *
     * @param name    the main key
     * @param aliases the aliases
     * @return this
     */
    public CommandBuilder group(String name, String... aliases) {
        ChildCommandAddress address = cur.getChild(name);
        if (address == null || !name.equals(address.getMainKey())) {
            address = new ChildCommandAddress();
            address.setupAsPlaceholder(name, aliases);
            cur.addChild(address);
        }
        cur = address;
        return this;
    }

    /**
     * Similar to {@link #group(String, String[])} but this will force overwrite any present group,
     * using the address passed. The address MUST be an instance of {@link ChildCommandAddress}.
     *
     * <p>The address must not have a parent or any keys</p>
     *
     * @param address the address object to use
     * @param name the main key
     * @param aliases any aliases
     * @return this
     * @throws IllegalArgumentException if any of the requirements set out above aren't met
     */
    public CommandBuilder group(ICommandAddress address, String name, String... aliases) {
        if (address.hasParent() || address.getMainKey() != null || !(address instanceof ChildCommandAddress)) {
            throw new IllegalArgumentException();
        }

        ChildCommandAddress asChild = (ChildCommandAddress) address;
        asChild.setupAsPlaceholder(name, aliases);
        cur.addChild(address);
        cur = asChild;
        return this;
    }

    /**
     * Sets the description of a group created by {@link #group(String, String...)}
     * Can be called subsequently to making a call to {@link #group(String, String...)}
     *
     * @param shortDescription a short description
     * @param description      the lines of a full description.
     * @return this
     * @throws IllegalStateException if the current group has no command
     */
    public CommandBuilder setGroupDescription(String shortDescription, String... description) {
        Command command = cur.getCommand();
        if (command == null) throw new IllegalStateException();
        cur.setCommand(command
                .setShortDescription(shortDescription)
                .setDescription(description));
        return this;
    }

    /**
     * Add a context filter to the command of the current group
     * @return this
     * @throws IllegalStateException if the current group has no command
     */
    public CommandBuilder addContextFilter(IContextFilter contextFilter) {
        Command command = cur.getCommand();
        if (command == null) throw new IllegalStateException();
        cur.setCommand(command
            .addContextFilter(contextFilter));
        return this;
    }

    /**
     * Add a required permission to the command of the current group
     * @return this
     * @throws IllegalStateException if the current group has no command
     */
    public CommandBuilder addPermission(String permission) {
        return addContextFilter(IContextFilter.permission(permission));
    }

    /**
     * Add a required permission to the command of the current group, which can be inherited
     * @return this
     * @throws IllegalStateException if the current group has no command
     */
    public CommandBuilder addInheritablePermission(String permission) {
        return addContextFilter(IContextFilter.inheritablePermission(permission));
    }

    /**
     * Jump up a level in the address
     *
     * @return this
     * @throws IllegalStateException if the address is empty
     *                               // has a depth of 0 // is at level 0
     */
    public CommandBuilder parent() {
        if (cur.hasParent()) {
            cur = cur.getParent();
            return this;
        }
        throw new IllegalStateException("No parent exists at this address");
    }

    /**
     * Jump to the root (empty) address,
     * such that a subsequent call to {@link #parent()}
     * will throw a {@link IllegalStateException}
     *
     * @return this
     */
    public CommandBuilder root() {
        cur = root;
        return this;
    }

    /**
     * Get the current address, as a space-separated string
     *
     * @return the current address
     */
    public String getAddress() {
        return cur.getAddress();
    }

    /**
     * Get the depth of the current address.
     * This is equivalent to {@code getAddress().split(" ").length}.
     * If the address is empty, the depth is 0.
     *
     * @return the depth
     */
    public int getDepth() {
        return cur.getDepth();
    }

    /**
     * Set the command at the current group. The command is set
     * a level higher than it would be if this were a call to {@link #addSubCommand(String, Command, String...)}
     * <p>
     * If a call to {@link #setGroupDescription(String, String...)} was made at the same address before,
     * the description is copied to the given executor.
     *
     * @param command the executor
     * @return this
     * @throws IllegalArgumentException if the command at the address is present and declared by the user,
     *                                  in other words, it's not a {@link PredefinedCommand}
     */
    public CommandBuilder setCommand(Command command) {
        Command current = cur.getCommand();
        if (current instanceof HelpCommand && current != HelpCommand.INSTANCE) {
            command.setShortDescription(current.getShortDescription());
            command.setDescription(current.getDescription());
        }

        cur.setCommand(command);
        return this;
    }

    /**
     * Configure the chat handler at this address. The chat handler
     * is used for all children down the tree if they don't explicitly have
     * their own chat handler configured. If this isn't configured,
     * {@code ChatHandlers.defaultChat()} is used.
     *
     * @param chatHandler the chat handler
     * @return this
     */
    public CommandBuilder setChatHandler(IChatHandler chatHandler) {
        cur.setChatHandler(chatHandler);
        return this;
    }

    /**
     * Add the parameter type to this builder's selector.
     *
     * @param type the type
     * @param <T>  the return type of the parameter type
     * @return this
     */
    public <T> CommandBuilder addParameterType(ParameterType<T, Void> type) {
        selector.addType(false, type);
        return this;
    }

    /**
     * Add the parameter type to this builder's selector.
     *
     * @param infolessAlias whether to also register the type with an infoless alias.
     *                      this increases the priority assigned to the type if no info object is present.
     * @param type          the type
     * @param <T>           the return type of the parameter type
     * @param <C>           the parameter config type (info object)
     * @return this
     */

    public <T, C> CommandBuilder addParameterType(boolean infolessAlias, ParameterType<T, C> type) {
        selector.addType(infolessAlias, type);
        return this;
    }

    /**
     * Get the dispatcher for the root address.
     * The dispatcher should be used to finally register all commands,
     * after they are all declared.
     *
     * @return the dispatcher
     */
    public ICommandDispatcher getDispatcher() {
        return root;
    }

    /**
     * Print debugging information about the current addresses and commands in this builder
     * A StackTraceElement indicating where this was called from is also included
     *
     * @return this
     */
    public CommandBuilder printDebugInformation() {
        String address = cur == root ? "<root>" : cur.getAddress();
        StackTraceElement caller = getCallsite();

        StringBuilder message = new StringBuilder("### CommandBuilder dump ###");
        message.append("\nCalled from ").append(caller);
        message.append("\nPosition: ").append(address);
        cur.appendDebugInformation(message, "", new HashSet<>());

        System.out.println(message);
        return this;
    }

    private static StackTraceElement getCallsite() {
        // [0] Thread.currentThread()
        // [1] CommandBuilder.getCallsite()
        // [2] Calling method
        // [3] Method calling the calling method
        StackTraceElement[] trace = Thread.currentThread().getStackTrace();
        return trace.length > 3 ? trace[3] : null;
    }

}