/*
 * The contents of this file are subject to the Interbase Public
 * License Version 1.0 (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.Inprise.com/IPL.html
 *
 * Software distributed under the License is distributed on an
 * "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express
 * or implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code was created by Inprise Corporation
 * and its predecessors. Portions created by Inprise Corporation are
 * Copyright (C) Inprise Corporation.
 *
 * All Rights Reserved.
 * Contributor(s): ______________________________________.
 */

#include "firebird.h"
#include "../jrd/jrd.h"
#include "../jrd/req.h"
#include "../jrd/rse.h"
#include "../jrd/cmp_proto.h"
#include "../jrd/evl_proto.h"
#include "../jrd/mov_proto.h"

#include "RecordSource.h"

using namespace Firebird;
using namespace Jrd;

static const char* const SCRATCH = "fb_merge_";

// -----------------------
// Data access: merge join
// -----------------------

MergeJoin::MergeJoin(CompilerScratch* csb, FB_SIZE_T count,
					 SortedStream* const* args, const NestValueArray* const* keys)
	: m_args(csb->csb_pool), m_keys(csb->csb_pool)
{
	const size_t size = sizeof(struct Impure) + count * sizeof(Impure::irsb_mrg_repeat);
	m_impure = CMP_impure(csb, static_cast<ULONG>(size));

	m_args.resize(count);
	m_keys.resize(count);

	for (FB_SIZE_T i = 0; i < count; i++)
	{
		fb_assert(args[i]);
		m_args[i] = args[i];

		fb_assert(keys[i]);
		m_keys[i] = keys[i];
	}
}

void MergeJoin::open(thread_db* tdbb) const
{
	jrd_req* const request = tdbb->getRequest();
	Impure* const impure = request->getImpure<Impure>(m_impure);

	impure->irsb_flags = irsb_open;

	for (FB_SIZE_T i = 0; i < m_args.getCount(); i++)
	{
		Impure::irsb_mrg_repeat* const tail = &impure->irsb_mrg_rpt[i];

		// open all the substreams for the sort-merge

		m_args[i]->open(tdbb);

		// reset equality group record positions

		tail->irsb_mrg_equal = -1;
		tail->irsb_mrg_equal_end = -1;
		tail->irsb_mrg_equal_current = -1;
		tail->irsb_mrg_last_fetched = -1;
		tail->irsb_mrg_order = tail - impure->irsb_mrg_rpt;

		MergeFile* const mfb = &tail->irsb_mrg_file;
		mfb->mfb_equal_records = 0;
		mfb->mfb_current_block = 0;
		mfb->mfb_record_size = ROUNDUP(m_args[i]->getLength(), FB_ALIGNMENT);
		mfb->mfb_block_size = MAX(mfb->mfb_record_size, MERGE_BLOCK_SIZE);
		mfb->mfb_blocking_factor = mfb->mfb_block_size / mfb->mfb_record_size;
		if (!mfb->mfb_block_data)
		{
			mfb->mfb_block_data = FB_NEW_POOL(*request->req_pool) UCHAR[mfb->mfb_block_size];
		}
	}
}

void MergeJoin::close(thread_db* tdbb) const
{
	jrd_req* const request = tdbb->getRequest();

	invalidateRecords(request);

	Impure* const impure = request->getImpure<Impure>(m_impure);

	if (impure->irsb_flags & irsb_open)
	{
		impure->irsb_flags &= ~irsb_open;

		for (FB_SIZE_T i = 0; i < m_args.getCount(); i++)
		{
			Impure::irsb_mrg_repeat* const tail = &impure->irsb_mrg_rpt[i];

			// close all the substreams for the sort-merge

			m_args[i]->close(tdbb);

			// Release memory associated with the merge file block and the sort file block.
			// Also delete the merge file if one exists.

			MergeFile* const mfb = &tail->irsb_mrg_file;
			delete mfb->mfb_space;
			mfb->mfb_space = NULL;

			delete[] mfb->mfb_block_data;
			mfb->mfb_block_data = NULL;
		}
	}
}

bool MergeJoin::getRecord(thread_db* tdbb) const
{
	if (--tdbb->tdbb_quantum < 0)
		JRD_reschedule(tdbb, true);

	jrd_req* const request = tdbb->getRequest();
	Impure* const impure = request->getImpure<Impure>(m_impure);

	if (!(impure->irsb_flags & irsb_open))
		return false;

	// If there is a record group already formed, fetch the next combination

	if (fetchRecord(tdbb, m_args.getCount() - 1))
		return true;

	// Assuming we are done with the current value group, advance each
	// stream one record. If any comes up dry, we're done.
	const NestConst<SortedStream>* highest_ptr = m_args.begin();
	FB_SIZE_T highest_index = 0;

	for (FB_SIZE_T i = 0; i < m_args.getCount(); i++)
	{
		const NestConst<SortedStream>* const ptr = &m_args[i];
		const SortedStream* const sort_rsb = *ptr;
		const NestValueArray* const sort_key = m_keys[i];
		Impure::irsb_mrg_repeat* const tail = &impure->irsb_mrg_rpt[i];

		MergeFile* const mfb = &tail->irsb_mrg_file;

		// reset equality group record positions

		tail->irsb_mrg_equal = 0;
		tail->irsb_mrg_equal_current = 0;
		tail->irsb_mrg_equal_end = 0;

		// If there is a record waiting, use it. Otherwise get another.

		SLONG record = tail->irsb_mrg_last_fetched;
		if (record >= 0)
		{
			tail->irsb_mrg_last_fetched = -1;
			const UCHAR* const last_data = getData(tdbb, mfb, record);
			mfb->mfb_current_block = 0;

			UCHAR* const first_data = getData(tdbb, mfb, 0);
			if (first_data != last_data)
				memcpy(first_data, last_data, sort_rsb->getLength());

			mfb->mfb_equal_records = 1;
			record = 0;
		}
		else
		{
			mfb->mfb_current_block = 0;
			mfb->mfb_equal_records = 0;
			if ((record = getRecord(tdbb, i)) < 0)
				return false;
		}

		// map data into target records and do comparison

		sort_rsb->mapData(tdbb, request, getData(tdbb, mfb, record));
		if (ptr != highest_ptr && compare(tdbb, m_keys[highest_index], sort_key) < 0)
		{
			highest_ptr = ptr;
			highest_index = i;
		}
	}

	// Loop thru the streams advancing each up to the target value.
	// If any exceeds the target value, start over.

	while (true)
	{
		bool recycle = false;

		for (FB_SIZE_T i = 0; i < m_args.getCount(); i++)
		{
			const NestConst<SortedStream>* const ptr = &m_args[i];
			const SortedStream* const sort_rsb = *ptr;
			const NestValueArray* const sort_key = m_keys[i];
			Impure::irsb_mrg_repeat* const tail = &impure->irsb_mrg_rpt[i];

			if (highest_ptr != ptr)
			{
				int result;
				while ( (result = compare(tdbb, m_keys[highest_index], sort_key)) )
				{
					if (result < 0)
					{
						highest_ptr = ptr;
						highest_index = i;
						recycle = true;
						break;
					}
					MergeFile* const mfb = &tail->irsb_mrg_file;
					mfb->mfb_current_block = 0;
					mfb->mfb_equal_records = 0;

					const SLONG record = getRecord(tdbb, i);
					if (record < 0)
						return false;

					sort_rsb->mapData(tdbb, request, getData(tdbb, mfb, record));
				}

				if (recycle)
					break;
			}
		}

		if (!recycle)
			break;
	}

	// finally compute equality group for each stream in sort/merge

	for (FB_SIZE_T i = 0; i < m_args.getCount(); i++)
	{
		const SortedStream* const sort_rsb = m_args[i];
		Impure::irsb_mrg_repeat* const tail = &impure->irsb_mrg_rpt[i];

		MergeFile* const mfb = &tail->irsb_mrg_file;

		UCharBuffer key;
		const ULONG key_length = sort_rsb->getKeyLength();
		UCHAR* const first_data = key.getBuffer(key_length);
		memcpy(first_data, getData(tdbb, mfb, 0), key_length);

		SLONG record;
		while ((record = getRecord(tdbb, i)) >= 0)
		{
			const UCHAR* p = first_data;
			const UCHAR* q = getData(tdbb, mfb, record);

			if (!sort_rsb->compareKeys(p, q))
			{
				tail->irsb_mrg_last_fetched = record;
				break;
			}

			tail->irsb_mrg_equal_end = record;
		}

		if (mfb->mfb_current_block)
		{
			if (!mfb->mfb_space)
			{
				MemoryPool& pool = *getDefaultMemoryPool();
				mfb->mfb_space = FB_NEW_POOL(pool) TempSpace(pool, SCRATCH, false);
			}

			Sort::writeBlock(mfb->mfb_space, mfb->mfb_block_size * mfb->mfb_current_block,
							 mfb->mfb_block_data, mfb->mfb_block_size);
		}
	}

	// Optimize cross product of equivalence groups by ordering the streams
	// from left (outermost) to right (innermost) by descending cardinality
	// of merge blocks. This ordering will vary for each set of equivalence
	// groups and cannot be statically assigned by the optimizer.

	typedef Stack<Impure::irsb_mrg_repeat*> ImrStack;
	ImrStack best_tails;

	Impure::irsb_mrg_repeat* tail = impure->irsb_mrg_rpt;
	for (const Impure::irsb_mrg_repeat* const tail_end = tail + m_args.getCount();
		 tail < tail_end; tail++)
	{
		Impure::irsb_mrg_repeat* best_tail = NULL;

		ULONG most_blocks = 0;
		for (Impure::irsb_mrg_repeat* tail2 = impure->irsb_mrg_rpt; tail2 < tail_end; tail2++)
		{
			ImrStack::iterator stack(best_tails);
			for (; stack.hasData(); ++stack)
			{
				if (stack.object() == tail2)
					break;
			}

			if (stack.hasData())
				continue;

			MergeFile* const mfb = &tail2->irsb_mrg_file;
			ULONG blocks = mfb->mfb_equal_records / mfb->mfb_blocking_factor;
			if (++blocks > most_blocks)
			{
				most_blocks = blocks;
				best_tail = tail2;
			}
		}

		best_tails.push(best_tail);
		tail->irsb_mrg_order = best_tail - impure->irsb_mrg_rpt;
	}

	return true;
}

bool MergeJoin::refetchRecord(thread_db* /*tdbb*/) const
{
	return true;
}

bool MergeJoin::lockRecord(thread_db* /*tdbb*/) const
{
	status_exception::raise(Arg::Gds(isc_record_lock_not_supp));
	return false; // compiler silencer
}

void MergeJoin::print(thread_db* tdbb, string& plan, bool detailed, unsigned level) const
{
	if (detailed)
	{
		plan += printIndent(++level) + "Merge Join (inner)";

		for (FB_SIZE_T i = 0; i < m_args.getCount(); i++)
			m_args[i]->print(tdbb, plan, true, level);
	}
	else
	{
		level++;
		plan += "MERGE (";
		for (FB_SIZE_T i = 0; i < m_args.getCount(); i++)
		{
			if (i)
				plan += ", ";

			m_args[i]->print(tdbb, plan, false, level);
		}
		plan += ")";
	}
}

void MergeJoin::markRecursive()
{
	for (FB_SIZE_T i = 0; i < m_args.getCount(); i++)
		m_args[i]->markRecursive();
}

void MergeJoin::findUsedStreams(StreamList& streams, bool expandAll) const
{
	for (FB_SIZE_T i = 0; i < m_args.getCount(); i++)
		m_args[i]->findUsedStreams(streams, expandAll);
}

void MergeJoin::invalidateRecords(jrd_req* request) const
{
	for (FB_SIZE_T i = 0; i < m_args.getCount(); i++)
		m_args[i]->invalidateRecords(request);
}

void MergeJoin::nullRecords(thread_db* tdbb) const
{
	for (FB_SIZE_T i = 0; i < m_args.getCount(); i++)
		m_args[i]->nullRecords(tdbb);
}

int MergeJoin::compare(thread_db* tdbb, const NestValueArray* node1,
	const NestValueArray* node2) const
{
	jrd_req* const request = tdbb->getRequest();

	const NestConst<ValueExprNode>* ptr1 = node1->begin();
	const NestConst<ValueExprNode>* ptr2 = node2->begin();

	for (const NestConst<ValueExprNode>* const end = node1->end(); ptr1 != end; ++ptr1, ++ptr2)
	{
		const dsc* const desc1 = EVL_expr(tdbb, request, *ptr1);
		const bool null1 = (request->req_flags & req_null);

		const dsc* const desc2 = EVL_expr(tdbb, request, *ptr2);
		const bool null2 = (request->req_flags & req_null);

		if (null1 && !null2)
			return -1;

		if (null2 && !null1)
			return 1;

		if (!null1 && !null2)
		{
			const int result = MOV_compare(desc1, desc2);

			if (result != 0)
				return result;
		}
	}

	return 0;
}

UCHAR* MergeJoin::getData(thread_db* /*tdbb*/, MergeFile* mfb, SLONG record) const
{
	fb_assert(record >= 0 && record < (SLONG) mfb->mfb_equal_records);

	const ULONG merge_block = record / mfb->mfb_blocking_factor;
	if (merge_block != mfb->mfb_current_block)
	{
		Sort::readBlock(mfb->mfb_space, mfb->mfb_block_size * merge_block,
						mfb->mfb_block_data, mfb->mfb_block_size);
		mfb->mfb_current_block = merge_block;
	}

	const ULONG merge_offset = (record % mfb->mfb_blocking_factor) * mfb->mfb_record_size;
	return mfb->mfb_block_data + merge_offset;
}

SLONG MergeJoin::getRecord(thread_db* tdbb, FB_SIZE_T index) const
{
	jrd_req* const request = tdbb->getRequest();
	Impure* const impure = request->getImpure<Impure>(m_impure);

	const SortedStream* const sort_rsb = m_args[index];
	Impure::irsb_mrg_repeat* const tail = &impure->irsb_mrg_rpt[index];

	const UCHAR* sort_data = sort_rsb->getData(tdbb);
	if (!sort_data)
		return -1;

	MergeFile* const mfb = &tail->irsb_mrg_file;
	const SLONG record = mfb->mfb_equal_records;

	const ULONG merge_block = record / mfb->mfb_blocking_factor;
	if (merge_block != mfb->mfb_current_block)
	{
		if (!mfb->mfb_space)
		{
			MemoryPool& pool = *getDefaultMemoryPool();
			mfb->mfb_space = FB_NEW_POOL(pool) TempSpace(pool, SCRATCH, false);
		}

		Sort::writeBlock(mfb->mfb_space, mfb->mfb_block_size * mfb->mfb_current_block,
						 mfb->mfb_block_data, mfb->mfb_block_size);
		mfb->mfb_current_block = merge_block;
	}

	const ULONG merge_offset = (record % mfb->mfb_blocking_factor) * mfb->mfb_record_size;
	UCHAR* merge_data = mfb->mfb_block_data + merge_offset;

	memcpy(merge_data, sort_data, sort_rsb->getLength());
	++mfb->mfb_equal_records;

	return record;
}

bool MergeJoin::fetchRecord(thread_db* tdbb, FB_SIZE_T index) const
{
	jrd_req* const request = tdbb->getRequest();
	Impure* const impure = request->getImpure<Impure>(m_impure);
	Impure::irsb_mrg_repeat* tail = &impure->irsb_mrg_rpt[index];

	const SSHORT m = tail->irsb_mrg_order;
	tail = &impure->irsb_mrg_rpt[m];
	const SortedStream* const sort_rsb = m_args[m];

	SLONG record = tail->irsb_mrg_equal_current;
	++record;

	if (record > tail->irsb_mrg_equal_end)
	{
		if (index == 0 || !fetchRecord(tdbb, index - 1))
			return false;

		record = tail->irsb_mrg_equal;
	}

	tail->irsb_mrg_equal_current = record;

	MergeFile* const mfb = &tail->irsb_mrg_file;
	sort_rsb->mapData(tdbb, request, getData(tdbb, mfb, record));

	return true;
}
