/*
 * This file is part of ComputerCraft - http://www.computercraft.info
 * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
 * Send enquiries to dratcliffe@gmail.com
 */

package dan200.computercraft.core.apis;

import dan200.computercraft.api.filesystem.IMount;
import dan200.computercraft.api.filesystem.IWritableMount;
import dan200.computercraft.api.lua.ILuaAPI;
import dan200.computercraft.api.lua.ILuaContext;
import dan200.computercraft.api.lua.LuaException;
import dan200.computercraft.api.peripheral.IPeripheral;
import dan200.computercraft.core.computer.Computer;
import dan200.computercraft.core.computer.ComputerThread;
import dan200.computercraft.core.computer.ITask;
import dan200.computercraft.core.tracking.TrackingField;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import static dan200.computercraft.core.apis.ArgumentHelper.getString;

public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChangeListener
{
    private class PeripheralWrapper extends ComputerAccess
    {
        private final String m_side;
        private final IPeripheral m_peripheral;

        private String m_type;
        private String[] m_methods;
        private Map<String, Integer> m_methodMap;
        private boolean m_attached;

        public PeripheralWrapper( IPeripheral peripheral, String side )
        {
            super( m_environment );
            m_side = side;
            m_peripheral = peripheral;
            m_attached = false;

            m_type = peripheral.getType();
            m_methods = peripheral.getMethodNames();
            assert (m_type != null);
            assert (m_methods != null);

            m_methodMap = new HashMap<>();
            for( int i = 0; i < m_methods.length; i++ )
            {
                if( m_methods[i] != null )
                {
                    m_methodMap.put( m_methods[i], i );
                }
            }
        }

        public IPeripheral getPeripheral()
        {
            return m_peripheral;
        }

        public String getType()
        {
            return m_type;
        }

        public String[] getMethods()
        {
            return m_methods;
        }

        public synchronized boolean isAttached()
        {
            return m_attached;
        }

        public synchronized void attach()
        {
            m_attached = true;
            m_peripheral.attach( this );
        }

        public void detach()
        {
            // Call detach
            m_peripheral.detach( this );

            synchronized( this )
            {
                // Unmount everything the detach function forgot to do
                unmountAll();
            }

            m_attached = false;
        }

        public Object[] call( ILuaContext context, String methodName, Object[] arguments ) throws LuaException, InterruptedException
        {
            int method = -1;
            synchronized( this )
            {
                if( m_methodMap.containsKey( methodName ) )
                {
                    method = m_methodMap.get( methodName );
                }
            }
            if( method >= 0 )
            {
                m_environment.addTrackingChange( TrackingField.PERIPHERAL_OPS );
                return m_peripheral.callMethod( this, context, method, arguments );
            }
            else
            {
                throw new LuaException( "No such method " + methodName );
            }
        }

        // IComputerAccess implementation
        @Override
        public synchronized String mount( @Nonnull String desiredLoc, @Nonnull IMount mount, @Nonnull String driveName )
        {
            if( !m_attached )
            {
                throw new RuntimeException( "You are not attached to this Computer" );
            }

            return super.mount( desiredLoc, mount, driveName );
        }

        @Override
        public synchronized String mountWritable( @Nonnull String desiredLoc, @Nonnull IWritableMount mount, @Nonnull String driveName )
        {
            if( !m_attached )
            {
                throw new RuntimeException( "You are not attached to this Computer" );
            }

            return super.mountWritable( desiredLoc, mount, driveName );
        }

        @Override
        public synchronized void unmount( String location )
        {
            if( !m_attached )
            {
                throw new RuntimeException( "You are not attached to this Computer" );
            }

            super.unmount( location );
        }

        @Override
        public int getID()
        {
            if( !m_attached )
            {
                throw new RuntimeException( "You are not attached to this Computer" );
            }
            return super.getID();
        }

        @Override
        public void queueEvent( @Nonnull final String event, final Object[] arguments )
        {
            if( !m_attached )
            {
                throw new RuntimeException( "You are not attached to this Computer" );
            }
            super.queueEvent( event, arguments );
        }

        @Nonnull
        @Override
        public String getAttachmentName()
        {
            if( !m_attached )
            {
                throw new RuntimeException( "You are not attached to this Computer" );
            }
            return m_side;
        }

        @Nonnull
        @Override
        public Map<String, IPeripheral> getAvailablePeripherals()
        {
            if( !m_attached )
            {
                throw new RuntimeException( "You are not attached to this Computer" );
            }

            Map<String, IPeripheral> peripherals = new HashMap<>();
            for( PeripheralWrapper wrapper : m_peripherals )
            {
                if( wrapper != null && wrapper.isAttached() )
                {
                    peripherals.put( wrapper.getAttachmentName(), wrapper.getPeripheral() );
                }
            }

            return Collections.unmodifiableMap( peripherals );
        }

        @Nullable
        @Override
        public IPeripheral getAvailablePeripheral( @Nonnull String name )
        {
            if( !m_attached )
            {
                throw new RuntimeException( "You are not attached to this Computer" );
            }

            for( PeripheralWrapper wrapper : m_peripherals )
            {
                if( wrapper != null && wrapper.isAttached() && wrapper.getAttachmentName().equals( name ) )
                {
                    return wrapper.getPeripheral();
                }
            }
            return null;
        }
    }

    private final IAPIEnvironment m_environment;
    private final PeripheralWrapper[] m_peripherals;
    private boolean m_running;

    public PeripheralAPI( IAPIEnvironment _environment )
    {
        m_environment = _environment;
        m_environment.setPeripheralChangeListener( this );

        m_peripherals = new PeripheralWrapper[6];
        for( int i = 0; i < 6; i++ )
        {
            m_peripherals[i] = null;
        }

        m_running = false;
    }

    // IPeripheralChangeListener

    @Override
    public void onPeripheralChanged( int side, IPeripheral newPeripheral )
    {
        synchronized( m_peripherals )
        {
            if( m_peripherals[side] != null )
            {
                // Queue a detachment
                final PeripheralWrapper wrapper = m_peripherals[side];
                ComputerThread.queueTask( new ITask()
                {
                    @Override
                    public Computer getOwner()
                    {
                        return m_environment.getComputer();
                    }

                    @Override
                    public void execute()
                    {
                        synchronized( m_peripherals )
                        {
                            if( wrapper.isAttached() )
                            {
                                wrapper.detach();
                            }
                        }
                    }
                }, null );

                // Queue a detachment event
                m_environment.queueEvent( "peripheral_detach", new Object[] { IAPIEnvironment.SIDE_NAMES[side] } );
            }

            // Assign the new peripheral
            if( newPeripheral != null )
            {
                m_peripherals[side] = new PeripheralWrapper( newPeripheral, IAPIEnvironment.SIDE_NAMES[side] );
            }
            else
            {
                m_peripherals[side] = null;
            }

            if( m_peripherals[side] != null )
            {
                // Queue an attachment
                final PeripheralWrapper wrapper = m_peripherals[side];
                ComputerThread.queueTask( new ITask()
                {
                    @Override
                    public Computer getOwner()
                    {
                        return m_environment.getComputer();
                    }

                    @Override
                    public void execute()
                    {
                        synchronized( m_peripherals )
                        {
                            if( m_running && !wrapper.isAttached() )
                            {
                                wrapper.attach();
                            }
                        }
                    }
                }, null );

                // Queue an attachment event
                m_environment.queueEvent( "peripheral", new Object[] { IAPIEnvironment.SIDE_NAMES[side] } );
            }
        }
    }

    // ILuaAPI implementation

    @Override
    public String[] getNames()
    {
        return new String[] {
            "peripheral"
        };
    }

    @Override
    public void startup()
    {
        synchronized( m_peripherals )
        {
            m_running = true;
            for( int i = 0; i < 6; i++ )
            {
                PeripheralWrapper wrapper = m_peripherals[i];
                if( wrapper != null && !wrapper.isAttached() )
                {
                    wrapper.attach();
                }
            }
        }
    }

    @Override
    public void shutdown()
    {
        synchronized( m_peripherals )
        {
            m_running = false;
            for( int i = 0; i < 6; i++ )
            {
                PeripheralWrapper wrapper = m_peripherals[i];
                if( wrapper != null && wrapper.isAttached() )
                {
                    wrapper.detach();
                }
            }
        }
    }

    @Nonnull
    @Override
    public String[] getMethodNames()
    {
        return new String[] {
            "isPresent",
            "getType",
            "getMethods",
            "call"
        };
    }

    @Override
    public Object[] callMethod( @Nonnull ILuaContext context, int method, @Nonnull Object[] args ) throws LuaException, InterruptedException
    {
        switch( method )
        {
            case 0:
            {
                // isPresent
                boolean present = false;
                int side = parseSide( args );
                if( side >= 0 )
                {
                    synchronized( m_peripherals )
                    {
                        PeripheralWrapper p = m_peripherals[side];
                        if( p != null )
                        {
                            present = true;
                        }
                    }
                }
                return new Object[] { present };
            }
            case 1:
            {
                // getType
                String type = null;
                int side = parseSide( args );
                if( side >= 0 )
                {
                    synchronized( m_peripherals )
                    {
                        PeripheralWrapper p = m_peripherals[side];
                        if( p != null )
                        {
                            type = p.getType();
                        }
                    }
                    if( type != null )
                    {
                        return new Object[] { type };
                    }
                }
                return null;
            }
            case 2:
            {
                // getMethods
                String[] methods = null;
                int side = parseSide( args );
                if( side >= 0 )
                {
                    synchronized( m_peripherals )
                    {
                        PeripheralWrapper p = m_peripherals[side];
                        if( p != null )
                        {
                            methods = p.getMethods();
                        }
                    }
                }
                if( methods != null )
                {
                    Map<Object, Object> table = new HashMap<>();
                    for( int i = 0; i < methods.length; i++ )
                    {
                        table.put( i + 1, methods[i] );
                    }
                    return new Object[] { table };
                }
                return null;
            }
            case 3:
            {
                // call
                int side = parseSide( args );
                String methodName = getString( args, 1 );
                Object[] methodArgs = Arrays.copyOfRange( args, 2, args.length );

                if( side >= 0 )
                {
                    PeripheralWrapper p;
                    synchronized( m_peripherals )
                    {
                        p = m_peripherals[side];
                    }
                    if( p != null )
                    {
                        return p.call( context, methodName, methodArgs );
                    }
                }
                throw new LuaException( "No peripheral attached" );
            }
            default:
            {
                return null;
            }
        }
    }

    // Privates

    private int parseSide( Object[] args ) throws LuaException
    {
        String side = getString( args, 0 );
        for( int n = 0; n < IAPIEnvironment.SIDE_NAMES.length; n++ )
        {
            if( side.equals( IAPIEnvironment.SIDE_NAMES[n] ) )
            {
                return n;
            }
        }
        return -1;
    }
}