
/*
 * Copyright 2011-2022 Cuberite Contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "Globals.h"
#include "BlockPiston.h"
#include "../BlockInfo.h"
#include "../Item.h"
#include "../World.h"
#include "../Entities/Player.h"
//#include "../BlockInServerPluginInterface.h"
#include "ChunkInterface.h"





#define PISTON_MAX_PUSH_DISTANCE 12





Vector3i cBlockPistonHandler::MetadataToOffset(NIBBLETYPE a_PistonMeta)
{
	switch (a_PistonMeta & 0x07)
	{
		case 0: return Vector3i( 0, -1,  0);
		case 1: return Vector3i( 0,  1,  0);
		case 2: return Vector3i( 0,  0, -1);
		case 3: return Vector3i( 0,  0,  1);
		case 4: return Vector3i(-1,  0,  0);
		case 5: return Vector3i( 1,  0,  0);
		default:
		{
			LOGWARNING("%s: invalid direction %d, ignoring", __FUNCTION__, a_PistonMeta & 0x07);
			ASSERT(!"Invalid direction");
			return Vector3i();
		}
	}
}





void cBlockPistonHandler::ExtendPiston(Vector3i a_BlockPos, cWorld & a_World)
{
	{
		// Broadcast block action first. Will do nothing if piston cannot in fact push

		BLOCKTYPE pistonBlock;
		NIBBLETYPE pistonMeta;
		a_World.GetBlockTypeMeta(a_BlockPos, pistonBlock, pistonMeta);
		a_World.BroadcastBlockAction(a_BlockPos, PistonExtendAction, pistonMeta, pistonBlock);
	}

	// Client expects the server to "play" the animation before setting the final blocks
	// However, we don't confuse animation with the underlying state of the world, so emulate by delaying 1 tick
	// (Probably why vanilla has so many dupe glitches with sand and pistons lolol)

	a_World.ScheduleTask(1_tick, [a_BlockPos](cWorld & World)
		{
			BLOCKTYPE pistonBlock;
			NIBBLETYPE pistonMeta;
			World.GetBlockTypeMeta(a_BlockPos, pistonBlock, pistonMeta);

			if ((pistonBlock != E_BLOCK_PISTON) && !IsSticky(pistonBlock))
			{
				// Ensure we operate on a piston to avoid spurious behaviour
				// Note that the scheduled task may result in the block type of a_BlockPos changing
				return;
			}

			if (IsExtended(pistonMeta))
			{
				// Already extended, bail out
				return;
			}

			Vector3i pushDir = MetadataToOffset(pistonMeta);
			Vector3iSet blocksPushed;
			if (!CanPushBlock(a_BlockPos + pushDir, World, true, blocksPushed, pushDir))
			{
				// Can't push anything, bail out
				return;
			}
			PushBlocks(blocksPushed, World, pushDir);

			// Set the extension and the piston base correctly
			Vector3i extensionPos = a_BlockPos + pushDir;
			World.SetBlock(a_BlockPos, pistonBlock, pistonMeta | 0x8);
			World.SetBlock(extensionPos, E_BLOCK_PISTON_EXTENSION, pistonMeta | (IsSticky(pistonBlock) ? 8 : 0));

			// Play sound effect only if extended successfully
			World.BroadcastSoundEffect("block.piston.extend", a_BlockPos, 0.5f, 0.7f);
		}
	);
}





void cBlockPistonHandler::RetractPiston(Vector3i a_BlockPos, cWorld & a_World)
{
	{
		BLOCKTYPE pistonBlock;
		NIBBLETYPE pistonMeta;
		a_World.GetBlockTypeMeta(a_BlockPos, pistonBlock, pistonMeta);
		a_World.BroadcastBlockAction(a_BlockPos, PistonRetractAction, pistonMeta, pistonBlock);
	}

	a_World.ScheduleTask(1_tick, [a_BlockPos](cWorld & World)
		{
			BLOCKTYPE pistonBlock;
			NIBBLETYPE pistonMeta;
			World.GetBlockTypeMeta(a_BlockPos, pistonBlock, pistonMeta);

			if ((pistonBlock != E_BLOCK_PISTON) && !IsSticky(pistonBlock))
			{
				// Ensure we operate on a piston to avoid spurious behaviour
				// Note that the scheduled task may result in the block type of a_BlockPos changing
				return;
			}

			if (!IsExtended(pistonMeta))
			{
				// Already retracted, bail out
				return;
			}

			Vector3i pushDir = MetadataToOffset(pistonMeta);

			// Check the extension:
			Vector3i extensionPos = a_BlockPos + pushDir;
			if (World.GetBlock(extensionPos) != E_BLOCK_PISTON_EXTENSION)
			{
				LOGD("%s: Piston without an extension - still extending, or just in an invalid state?", __FUNCTION__);
				return;
			}

			// Remove extension, update base state:
			World.SetBlock(extensionPos, E_BLOCK_AIR, 0);
			World.SetBlock(a_BlockPos, pistonBlock, pistonMeta & ~(8));

			// (Retraction is always successful, but play in the task for consistency)
			World.BroadcastSoundEffect("block.piston.contract", a_BlockPos, 0.5f, 0.7f);

			if (!IsSticky(pistonBlock))
			{
				// No need for block pulling, bail out
				return;
			}

			// Get the block to pull
			Vector3i AdjustedPosition = a_BlockPos + pushDir * 2;
			// Try to "push" the pulling block in the opposite direction
			pushDir *= -1;

			Vector3iSet pushedBlocks;
			if (!CanPushBlock(AdjustedPosition, World, false, pushedBlocks, pushDir))
			{
				// Not pushable, bail out
				return;
			}

			PushBlocks(pushedBlocks, World, pushDir);
		}
	);
}





void cBlockPistonHandler::PushBlocks(
	const Vector3iSet & a_BlocksToPush,
	cWorld & a_World, const Vector3i & a_PushDir
)
{
	// Sort blocks to move the blocks first, which are farthest away from the piston
	// This prevents the overwriting of existing blocks
	std::vector<Vector3i> sortedBlocks(a_BlocksToPush.begin(), a_BlocksToPush.end());
	std::sort(sortedBlocks.begin(), sortedBlocks.end(), [a_PushDir](const Vector3i & a, const Vector3i & b)
	{
		return (a.Dot(a_PushDir) > b.Dot(a_PushDir));
	});

	// Move every block
	BLOCKTYPE moveBlock;
	NIBBLETYPE moveMeta;
	for (auto & moveBlockPos : sortedBlocks)
	{
		a_World.GetBlockTypeMeta(moveBlockPos, moveBlock, moveMeta);

		if (cBlockInfo::IsPistonBreakable(moveBlock))
		{
			// Block is breakable, drop it:
			a_World.DropBlockAsPickups(moveBlockPos, nullptr, nullptr);
		}
		else
		{
			// Not breakable, just move it
			a_World.SetBlock(moveBlockPos, E_BLOCK_AIR, 0);
			moveBlockPos += a_PushDir;
			a_World.SetBlock(moveBlockPos, moveBlock, moveMeta);
		}
	}
}





bool cBlockPistonHandler::CanPushBlock(
	const Vector3i & a_BlockPos, cWorld & a_World, bool a_RequirePushable,
	Vector3iSet & a_BlocksPushed, const Vector3i & a_PushDir
)
{
	if (!cChunkDef::IsValidHeight(a_BlockPos))
	{
		// Can't push a void block.
		return false;
	}

	const static std::array<Vector3i, 6> pushingDirs =
	{
		{
			Vector3i(-1,  0,  0), Vector3i(1, 0, 0),
			Vector3i( 0, -1,  0), Vector3i(0, 1, 0),
			Vector3i( 0,  0, -1), Vector3i(0, 0, 1)
		}
	};

	BLOCKTYPE currBlock;
	NIBBLETYPE currMeta;
	a_World.GetBlockTypeMeta(a_BlockPos, currBlock, currMeta);

	if (currBlock == E_BLOCK_AIR)
	{
		// Air can be pushed
		return true;
	}

	if (!a_RequirePushable && cBlockInfo::IsPistonBreakable(currBlock))
	{
		// Block should not be broken, when it's not in the pushing direction
		return true;
	}

	if (!CanPush(currBlock, currMeta))
	{
		// When it's not required to push this block, don't fail
		return !a_RequirePushable;
	}

	if (a_BlocksPushed.size() >= PISTON_MAX_PUSH_DISTANCE)
	{
		// Do not allow to push too much blocks
		return false;
	}

	if (!a_BlocksPushed.insert(a_BlockPos).second || cBlockInfo::IsPistonBreakable(currBlock))
	{
		return true;  // Element exist already
	}

	if (currBlock == E_BLOCK_SLIME_BLOCK)
	{
		// Try to push the other directions
		for (const auto & testDir : pushingDirs)
		{
			if (!CanPushBlock(a_BlockPos + testDir, a_World, false, a_BlocksPushed, a_PushDir))
			{
				// When it's not possible for a direction, then fail
				return false;
			}
		}
	}

	// Try to push the block in front of this block
	return CanPushBlock(a_BlockPos + a_PushDir, a_World, true, a_BlocksPushed, a_PushDir);
}





void cBlockPistonHandler::OnBroken(
	cChunkInterface & a_ChunkInterface, cWorldInterface & a_WorldInterface,
	Vector3i a_BlockPos,
	BLOCKTYPE a_OldBlockType, NIBBLETYPE a_OldBlockMeta,
	const cEntity * a_Digger
) const
{
	UNUSED(a_Digger);
	if (!IsExtended(a_OldBlockMeta))
	{
		return;
	}

	const auto Extension = a_BlockPos + MetadataToOffset(a_OldBlockMeta);
	if (
		cChunkDef::IsValidHeight(Extension) &&
		(a_ChunkInterface.GetBlock(Extension) == E_BLOCK_PISTON_EXTENSION)
	)
	{
		// If the piston is extended, destroy the extension as well:
		a_ChunkInterface.SetBlock(Extension, E_BLOCK_AIR, 0);
	}
}





////////////////////////////////////////////////////////////////////////////////
// cBlockPistonHeadHandler:

void cBlockPistonHeadHandler::OnBroken(
	cChunkInterface & a_ChunkInterface, cWorldInterface & a_WorldInterface,
	Vector3i a_BlockPos,
	BLOCKTYPE a_OldBlockType, NIBBLETYPE a_OldBlockMeta,
	const cEntity * a_Digger
) const
{
	UNUSED(a_Digger);
	const auto Base = a_BlockPos - cBlockPistonHandler::MetadataToOffset(a_OldBlockMeta);
	if (!cChunkDef::IsValidHeight(Base))
	{
		return;
	}

	const auto Block = a_ChunkInterface.GetBlock(Base);
	if ((Block == E_BLOCK_PISTON) || (Block == E_BLOCK_STICKY_PISTON))
	{
		// Remove the base of the piston:
		a_ChunkInterface.SetBlock(Base, E_BLOCK_AIR, 0);
	}
}





cItems cBlockPistonHeadHandler::ConvertToPickups(const NIBBLETYPE a_BlockMeta, const cItem * const a_Tool) const
{
	// Give a normal\sticky piston base, not piston extension
	// With 1.7, the item forms of these technical blocks have been removed, so giving someone this will crash their client...
	return { cItem(((a_BlockMeta & 0x8) == 0x8) ? E_BLOCK_STICKY_PISTON : E_BLOCK_PISTON) };
}
