package net.rustnotmc.client;

import java.util.LinkedHashMap;
import java.util.Map;

import net.rustnotmc.api.client.ClientCommand;
import net.rustnotmc.api.client.CommandArgs;
import net.rustnotmc.api.client.CommandScope;
import net.rustnotmc.api.client.Commands;
import net.rustnotmc.loader.Log;
import net.rustnotmc.loader.ModLoader;

/**
 * The mod command table.
 *
 * Only a CLIENT scoped command is carried out here. SERVER and BOTH are not
 * consumed by the client at all: the line is left for the server to take, which
 * is the whole point of the scope. The client never decides an effect the server
 * owns.
 *
 * The table is shared by every mod, so a name can only be claimed once. A second
 * mod asking for a taken name is refused loudly rather than silently shadowing
 * the first, which would be miserable to debug.
 *
 * Lives in game-fork/src-overlay; src is regenerated on every build.
 */
final class RsxCommands implements Commands {

    private static final class Entry {
        final String owner;
        final ClientCommand handler;
        final CommandScope scope;

        Entry(String owner, ClientCommand handler, CommandScope scope) {
            this.owner = owner;
            this.handler = handler;
            this.scope = scope;
        }
    }

    private final Map<String, Entry> entries = new LinkedHashMap<String, Entry>();

    @Override
    public boolean register(String name, ClientCommand handler, CommandScope scope) {
        if (name == null || handler == null || scope == null) {
            return false;
        }
        String key = normalise(name);
        if (key.length() == 0) {
            return false;
        }
        String owner = registering();
        Entry clash = this.entries.get(key);
        if (clash != null) {
            if (clash.owner.equals(owner) && clash.handler == handler) {
                return true;
            }
            Log.warn("command /" + key + " is already registered by " + clash.owner
                    + "; the second registration was refused");
            return false;
        }
        this.entries.put(key, new Entry(owner, handler, scope));
        Log.info("registered command /" + key + " scope=" + scope.name().toLowerCase());
        return true;
    }

    @Override
    public boolean register(String name, ClientCommand handler) {
        return register(name, handler, CommandScope.CLIENT);
    }

    @Override
    public boolean isRegistered(String name) {
        return name != null && this.entries.containsKey(normalise(name));
    }

    @Override
    public CommandScope scopeOf(String name) {
        Entry e = name == null ? null : this.entries.get(normalise(name));
        return e == null ? null : e.scope;
    }

    @Override
    public int count() {
        return this.entries.size();
    }

    /**
     * Offers a typed line to the mod commands.
     *
     * @return true when the client carried it out and the line must not be sent
     *         on. False means the line is not a client command, which is the
     *         answer for SERVER and BOTH: the server has to see those.
     */
    boolean dispatch(String line, String sender) {
        if (line == null || !line.startsWith("/")) {
            return false;
        }
        String body = line.substring(1).trim();
        int space = body.indexOf(' ');
        String name = space < 0 ? body : body.substring(0, space);
        Entry entry = this.entries.get(normalise(name));
        if (entry == null || entry.scope != CommandScope.CLIENT) {
            return false;
        }
        try {
            entry.handler.run(CommandArgs.parse(body, sender));
        } catch (Throwable t) {
            Log.error("command /" + name + " failed", t);
        }
        return true;
    }

    private static String normalise(String name) {
        String v = name.trim();
        if (v.startsWith("/")) {
            v = v.substring(1);
        }
        return v.toLowerCase();
    }

    /**
     * Who is registering right now.
     *
     * The loader knows this because it is the one calling onConstruct, and the
     * game can read it without the loader ever depending on the game.
     */
    private static String registering() {
        String who = ModLoader.REGISTERING.get();
        return who == null ? "unknown" : who;
    }
}