/** @file RunStyles.cxx
 ** Data structure used to store sparse styles.
 **/
// Copyright 1998-2007 by Neil Hodgson <neilh@scintilla.org>
// The License.txt file describes the conditions under which this software may be distributed.

#include <cstddef>
#include <cstdlib>
#include <cstdint>
#include <cstring>
#include <cstdio>
#include <cstdarg>
#include <climits>

#include <stdexcept>
#include <string_view>
#include <vector>
#include <optional>
#include <algorithm>
#include <memory>

#include "Debugging.h"

#include "Position.h"
#include "SplitVector.h"
#include "Partitioning.h"
#include "RunStyles.h"

using namespace Scintilla::Internal;

// Find the first run at a position
template <typename DISTANCE, typename STYLE>
DISTANCE RunStyles<DISTANCE, STYLE>::RunFromPosition(DISTANCE position) const noexcept {
	DISTANCE run = starts.PartitionFromPosition(position);
	// Go to first element with this position
	while ((run > 0) && (position == starts.PositionFromPartition(run-1))) {
		run--;
	}
	return run;
}

// If there is no run boundary at position, insert one continuing style.
template <typename DISTANCE, typename STYLE>
DISTANCE RunStyles<DISTANCE, STYLE>::SplitRun(DISTANCE position) {
	DISTANCE run = RunFromPosition(position);
	const DISTANCE posRun = starts.PositionFromPartition(run);
	if (posRun < position) {
		STYLE runStyle = ValueAt(position);
		run++;
		starts.InsertPartition(run, position);
		styles.InsertValue(run, 1, runStyle);
	}
	return run;
}

template <typename DISTANCE, typename STYLE>
void RunStyles<DISTANCE, STYLE>::RemoveRun(DISTANCE run) {
	starts.RemovePartition(run);
	styles.DeleteRange(run, 1);
}

template <typename DISTANCE, typename STYLE>
void RunStyles<DISTANCE, STYLE>::RemoveRunIfEmpty(DISTANCE run) {
	if ((run < starts.Partitions()) && (starts.Partitions() > 1)) {
		if (starts.PositionFromPartition(run) == starts.PositionFromPartition(run+1)) {
			RemoveRun(run);
		}
	}
}

template <typename DISTANCE, typename STYLE>
void RunStyles<DISTANCE, STYLE>::RemoveRunIfSameAsPrevious(DISTANCE run) {
	if ((run > 0) && (run < starts.Partitions())) {
		const DISTANCE runBefore = run - 1;
		if (styles.ValueAt(runBefore) == styles.ValueAt(run)) {
			RemoveRun(run);
		}
	}
}

template <typename DISTANCE, typename STYLE>
RunStyles<DISTANCE, STYLE>::RunStyles() {
	styles.InsertValue(0, 2, 0);
}

template <typename DISTANCE, typename STYLE>
DISTANCE RunStyles<DISTANCE, STYLE>::Length() const noexcept {
	return starts.PositionFromPartition(starts.Partitions());
}

template <typename DISTANCE, typename STYLE>
STYLE RunStyles<DISTANCE, STYLE>::ValueAt(DISTANCE position) const noexcept {
	return styles.ValueAt(starts.PartitionFromPosition(position));
}

template <typename DISTANCE, typename STYLE>
DISTANCE RunStyles<DISTANCE, STYLE>::FindNextChange(DISTANCE position, DISTANCE end) const noexcept {
	const DISTANCE run = starts.PartitionFromPosition(position);
	if (run < starts.Partitions()) {
		const DISTANCE runChange = starts.PositionFromPartition(run);
		if (runChange > position)
			return runChange;
		const DISTANCE nextChange = starts.PositionFromPartition(run + 1);
		if (nextChange > position) {
			return nextChange;
		} else if (position < end) {
			return end;
		} else {
			return end + 1;
		}
	} else {
		return end + 1;
	}
}

template <typename DISTANCE, typename STYLE>
DISTANCE RunStyles<DISTANCE, STYLE>::StartRun(DISTANCE position) const noexcept {
	return starts.PositionFromPartition(starts.PartitionFromPosition(position));
}

template <typename DISTANCE, typename STYLE>
DISTANCE RunStyles<DISTANCE, STYLE>::EndRun(DISTANCE position) const noexcept {
	return starts.PositionFromPartition(starts.PartitionFromPosition(position) + 1);
}

template <typename DISTANCE, typename STYLE>
FillResult<DISTANCE> RunStyles<DISTANCE, STYLE>::FillRange(DISTANCE position, STYLE value, DISTANCE fillLength) {
	const FillResult<DISTANCE> resultNoChange{false, position, fillLength};
	if (fillLength <= 0) {
		return resultNoChange;
	}
	DISTANCE end = position + fillLength;
	if (end > Length()) {
		return resultNoChange;
	}
	DISTANCE runEnd = RunFromPosition(end);
	const STYLE valueCurrent = styles.ValueAt(runEnd);
	if (valueCurrent == value) {
		// End already has value so trim range.
		end = starts.PositionFromPartition(runEnd);
		if (position >= end) {
			// Whole range is already same as value so no action
			return resultNoChange;
		}
		fillLength = end - position;
	} else {
		const DISTANCE startRun = starts.PositionFromPartition(runEnd);
		if (position > startRun) {
			const DISTANCE runNext = runEnd + 1;
			const DISTANCE endRun = starts.PositionFromPartition(runNext);
			if (end < endRun) {
				// New piece is completely inside a run with a different value so its a simple
				// insertion of two points [ (position, value), (end, valueCurrent) ]
				const DISTANCE range[] { position, end};
				starts.InsertPartitions(runEnd + 1, range, 2);
				// Temporary runEndIndex silences non-useful arithmetic overflow warnings
				const ptrdiff_t runEndIndex = runEnd;
				styles.Insert(runEndIndex + 1, value);
				styles.Insert(runEndIndex + 2, valueCurrent);
				return { true, position, fillLength };
			}
		}
		runEnd = SplitRun(end);
	}
	DISTANCE runStart = RunFromPosition(position);
	if (styles.ValueAt(runStart) == value) {
		// Start is in expected value so trim range.
		runStart++;
		position = starts.PositionFromPartition(runStart);
		fillLength = end - position;
	} else {
		if (starts.PositionFromPartition(runStart) < position) {
			runStart = SplitRun(position);
			runEnd++;
		}
	}
	if (runStart < runEnd) {
		const FillResult<DISTANCE> result{ true, position, fillLength };
		styles.SetValueAt(runStart, value);
		// Remove each old run over the range
		for (DISTANCE run=runStart+1; run<runEnd; run++) {
			RemoveRun(runStart+1);
		}
		runEnd = RunFromPosition(end);
		RemoveRunIfSameAsPrevious(runEnd);
		RemoveRunIfSameAsPrevious(runStart);
		runEnd = RunFromPosition(end);
		RemoveRunIfEmpty(runEnd);
		return result;
	}
	return resultNoChange;
}

template <typename DISTANCE, typename STYLE>
void RunStyles<DISTANCE, STYLE>::SetValueAt(DISTANCE position, STYLE value) {
	FillRange(position, value, 1);
}

template <typename DISTANCE, typename STYLE>
void RunStyles<DISTANCE, STYLE>::InsertSpace(DISTANCE position, DISTANCE insertLength) {
	DISTANCE runStart = RunFromPosition(position);
	if (starts.PositionFromPartition(runStart) == position) {
		STYLE runStyle = ValueAt(position);
		// Inserting at start of run so make previous longer
		if (runStart == 0) {
			// Inserting at start of document so ensure 0
			if (runStyle) {
				styles.SetValueAt(0, STYLE());
				starts.InsertPartition(1, 0);
				styles.InsertValue(1, 1, runStyle);
				starts.InsertText(0, insertLength);
			} else {
				starts.InsertText(runStart, insertLength);
			}
		} else {
			if (runStyle) {
				starts.InsertText(runStart-1, insertLength);
			} else {
				// Insert at end of run so do not extend style
				starts.InsertText(runStart, insertLength);
			}
		}
	} else {
		starts.InsertText(runStart, insertLength);
	}
}

template <typename DISTANCE, typename STYLE>
void RunStyles<DISTANCE, STYLE>::DeleteAll() {
	starts = Partitioning<DISTANCE>();
	styles = SplitVector<STYLE>();
	styles.InsertValue(0, 2, 0);
}

template <typename DISTANCE, typename STYLE>
void RunStyles<DISTANCE, STYLE>::DeleteRange(DISTANCE position, DISTANCE deleteLength) {
	DISTANCE end = position + deleteLength;
	DISTANCE runStart = RunFromPosition(position);
	DISTANCE runEnd = RunFromPosition(end);
	if (runStart == runEnd) {
		// Deleting from inside one run
		starts.InsertText(runStart, -deleteLength);
		RemoveRunIfEmpty(runStart);
	} else {
		runStart = SplitRun(position);
		runEnd = SplitRun(end);
		starts.InsertText(runStart, -deleteLength);
		// Remove each old run over the range
		for (DISTANCE run=runStart; run<runEnd; run++) {
			RemoveRun(runStart);
		}
		RemoveRunIfEmpty(runStart);
		RemoveRunIfSameAsPrevious(runStart);
	}
}

template <typename DISTANCE, typename STYLE>
DISTANCE RunStyles<DISTANCE, STYLE>::Runs() const noexcept {
	return starts.Partitions();
}

template <typename DISTANCE, typename STYLE>
bool RunStyles<DISTANCE, STYLE>::AllSame() const noexcept {
	for (DISTANCE run = 1; run < starts.Partitions(); run++) {
		const DISTANCE runBefore = run - 1;
		if (styles.ValueAt(run) != styles.ValueAt(runBefore))
			return false;
	}
	return true;
}

template <typename DISTANCE, typename STYLE>
bool RunStyles<DISTANCE, STYLE>::AllSameAs(STYLE value) const noexcept {
	return AllSame() && (styles.ValueAt(0) == value);
}

template <typename DISTANCE, typename STYLE>
DISTANCE RunStyles<DISTANCE, STYLE>::Find(STYLE value, DISTANCE start) const noexcept {
	if (start < Length()) {
		DISTANCE run = start ? RunFromPosition(start) : 0;
		if (styles.ValueAt(run) == value)
			return start;
		run++;
		while (run < starts.Partitions()) {
			if (styles.ValueAt(run) == value)
				return starts.PositionFromPartition(run);
			run++;
		}
	}
	return -1;
}

template <typename DISTANCE, typename STYLE>
void RunStyles<DISTANCE, STYLE>::Check() const {
	if (Length() < 0) {
		throw std::runtime_error("RunStyles: Length can not be negative.");
	}
	if (starts.Partitions() < 1) {
		throw std::runtime_error("RunStyles: Must always have 1 or more partitions.");
	}
	if (starts.Partitions() != styles.Length()-1) {
		throw std::runtime_error("RunStyles: Partitions and styles different lengths.");
	}
	DISTANCE start=0;
	while (start < Length()) {
		const DISTANCE end = EndRun(start);
		if (start >= end) {
			throw std::runtime_error("RunStyles: Partition is 0 length.");
		}
		start = end;
	}
	if (styles.ValueAt(styles.Length()-1) != 0) {
		throw std::runtime_error("RunStyles: Unused style at end changed.");
	}
	for (ptrdiff_t j=1; j<styles.Length()-1; j++) {
		if (styles.ValueAt(j) == styles.ValueAt(j-1)) {
			throw std::runtime_error("RunStyles: Style of a partition same as previous.");
		}
	}
}

template class Scintilla::Internal::RunStyles<int, int>;
template class Scintilla::Internal::RunStyles<int, char>;
#if (PTRDIFF_MAX != INT_MAX) || defined(__HAIKU__) || defined(PTRDIFF_DOESNT_ALIAS_INT)
template class Scintilla::Internal::RunStyles<ptrdiff_t, int>;
template class Scintilla::Internal::RunStyles<ptrdiff_t, char>;
#endif
