PermissionAPI

Context.java

import net.minecraft.entity.Entity;
import net.minecraft.util.math.BlockPos;
import net.minecraft.world.IBlockAccess;

import javax.annotation.ParametersAreNonnullByDefault;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by LatvianModder on 26.05.2016.
 */
@ParametersAreNonnullByDefault
public class Context
{
    /**
     * Not recommended, only used when there really is no context available
     */
    public static final Context EMPTY = new Context();

    private IBlockAccess blockAccess;
    private Entity entity;
    private BlockPos blockPos;
    private Map<String, Object> custom;

    public Context()
    {
    }

    public Context(IBlockAccess w)
    {
        blockAccess = w;
    }

    public Context(Entity e)
    {
        blockAccess = e.worldObj;
        entity = e;
    }

    public Context(IBlockAccess w, BlockPos pos)
    {
        blockAccess = w;
        blockPos = pos;
    }

    public Context(Entity e, BlockPos pos)
    {
        blockAccess = e.worldObj;
        entity = e;
        blockPos = pos;
    }

    // IBlockAccess //

    public IBlockAccess getBlockAccess()
    {
        return blockAccess;
    }

    public Context setBlockAccess(IBlockAccess w)
    {
        blockAccess = w;
        return this;
    }

    public boolean hasBlockAccess()
    {
        return blockAccess != null;
    }

    // Entity //

    public Entity getEntity()
    {
        return entity;
    }

    public Context setEntity(Entity e)
    {
        blockAccess = e.worldObj;
        entity = e;
        return this;
    }

    public boolean hasEntity()
    {
        return entity != null;
    }

    // BlockPos //

    public BlockPos getBlockPos()
    {
        return blockPos;
    }

    public Context setBlockPos(BlockPos pos)
    {
        blockPos = pos;
        return this;
    }

    public boolean hasBlockPos()
    {
        return blockPos != null;
    }

    // Custom objects //

    public Object getCustomObject(String id)
    {
        return (custom == null || id.isEmpty()) ? null : custom.get(id);
    }

    public boolean hasCustomObject(String id)
    {
        return custom != null && !id.isEmpty() && custom.containsKey(id);
    }

    public Context setCustomObject(String id, Object obj)
    {
        if(custom == null)
        {
            custom = new HashMap<>();
        }

        custom.put(id, obj);
        return this;
    }
}

PermissionAPI.java

import com.feed_the_beast.ftbl.FTBLibMod;
import com.mojang.authlib.GameProfile;
import net.minecraft.server.MinecraftServer;
import net.minecraftforge.fml.common.FMLCommonHandler;

import javax.annotation.ParametersAreNonnullByDefault;

/**
 * Created by LatvianModder on 24.05.2016.
 */
@ParametersAreNonnullByDefault
public class PermissionAPI
{
    private static PermissionHandler permissionHandler;

    public static void setPermissionHandler(PermissionHandler handler)
    {
        if(permissionHandler != null)
        {
            FTBLibMod.logger.warn("Replacing " + permissionHandler.getClass().getName() + " with " + handler.getClass().getName());
        }

        permissionHandler = handler;
    }

    /**
     * @param profile          GameProfile of the player who is requesting permission
     * @param permission       Permission node, best if lowercase and contains '.'
     * @param defaultForPlayer Default value for players
     * @param context          Context for this permission. Do not use null, when there is no context available, use Context.EMPTY!
     * @return true, if player has permission, false if he does not.
     */
    public static boolean hasPermission(GameProfile profile, String permission, boolean defaultForPlayer, Context context)
    {
        if(permission.isEmpty())
        {
            throw new NullPointerException("Permission string can't be empty!");
        }

        MinecraftServer server = FMLCommonHandler.instance().getMinecraftServerInstance();

        if(server == null)
        {
            return true;
        }

        if(!server.isDedicatedServer() || server.getPlayerList().getOppedPlayers().getPermissionLevel(profile) > 0)
        {
            return true;
        }

        if(permissionHandler == null)
        {
            return defaultForPlayer;
        }

        switch(permissionHandler.hasPermission(profile, permission, context))
        {
            case ALLOW:
            {
                return true;
            }
            case DENY:
            {
                return false;
            }
            default:
            {
                return defaultForPlayer;
            }
        }
    }
}

PermissionHandler.java

import com.mojang.authlib.GameProfile;
import net.minecraftforge.fml.common.eventhandler.Event;

import javax.annotation.ParametersAreNonnullByDefault;

/**
 * Created by LatvianModder on 26.05.2016.
 */
@ParametersAreNonnullByDefault
public interface PermissionHandler
{
    Event.Result hasPermission(GameProfile profile, String permission, Context context);
}

LatvianModder, just give me easy-to-use wrappers like these: https://github.com/ForgeEssentials/ForgeEssentials/blob/189/develop/src/main/java/net/minecraftforge/permission/PermissionManager.java#L163

---

IMO the whole OpPermissionLevel system should be nuked and replaced with Permission API calls. (this is what sponge does)

So there shouldn't be a need to accommodate that.

---

Otherwise it looks good, let me call my permissions guy to give his input - @olee

As a refresher: MinecraftForge/MinecraftForge#2899