/*

* This file is part of Notepad Next.

* Copyright 2026 NotepadAI contributors

*

* Notepad Next is free software: you can redistribute it and/or modify

* it under the terms of the GNU General Public License as published by

* the Free Software Foundation, either version 3 of the License, or

* (at your option) any later version.

*

* Notepad Next is distributed in the hope that it will be useful,

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

* GNU General Public License for more details.

*

* You should have received a copy of the GNU General Public License

* along with Notepad Next. If not, see <https://www.gnu.org/licenses/>.

*/

#include <QtTest>

#include <QVector>

#include "ScrollbackBuffer.h"

#include <vterm.h>

#include <cstring>

// Helper: build a line of cells whose first character codepoint is the row tag

// and whose column index is encoded in attrs.bold so we can detect padding.

static QVector<VTermScreenCell> makeLine(int cols, uint32_t tag)

{

QVector<VTermScreenCell> row(cols);

for (int i = 0; i < cols; ++i) {

std::memset(&row[i], 0, sizeof(VTermScreenCell));

row[i].chars[0] = tag + static_cast<uint32_t>(i);

row[i].width = 1;

}

return row;

}

class TestScrollbackBuffer : public QObject

{

Q_OBJECT

private slots:

void empty_sizeAndIsEmpty();

void pushLine_appendsToBottom();

void pushLine_overCapacity_dropsOldest();

void popLine_takesMostRecent();

void popLine_emptyReturnsFalse();

void popLine_intoNarrowerCols_truncates();

void popLine_intoWiderCols_padsBlankCells();

void lineAt_outOfRange_returnsFalse();

void lineAt_returnsByHistoryIndex();

void lineAt_intoWiderCols_padsBlankCells();

void lineAt_intoNarrowerCols_truncates();

void clear_emptiesBuffer();

void setMaxLines_shrinks_dropsOldest();

void pushLine_returnsEvictionCount();

};

void TestScrollbackBuffer::empty_sizeAndIsEmpty()

{

ScrollbackBuffer sb(100);

QCOMPARE(sb.size(), 0);

QVERIFY(sb.isEmpty());

QCOMPARE(sb.maxLines(), 100);

}

void TestScrollbackBuffer::pushLine_appendsToBottom()

{

ScrollbackBuffer sb(100);

const auto line0 = makeLine(5, 100);

const auto line1 = makeLine(5, 200);

sb.pushLine(5, line0.constData());

sb.pushLine(5, line1.constData());

QCOMPARE(sb.size(), 2);

QVERIFY(!sb.isEmpty());

QVector<VTermScreenCell> out(5);

QVERIFY(sb.lineAt(0, 5, out.data()));

QCOMPARE(out[0].chars[0], 100u);

QCOMPARE(out[2].chars[0], 102u);

QVERIFY(sb.lineAt(1, 5, out.data()));

QCOMPARE(out[0].chars[0], 200u);

QCOMPARE(out[4].chars[0], 204u);

}

void TestScrollbackBuffer::pushLine_overCapacity_dropsOldest()

{

ScrollbackBuffer sb(3);

for (uint32_t i = 0; i < 5; ++i) {

const auto row = makeLine(2, 1000u + i * 10);

sb.pushLine(2, row.constData());

}

QCOMPARE(sb.size(), 3);

// Oldest retained line should be the third push (tag 1020), then 1030, then 1040.

QVector<VTermScreenCell> out(2);

QVERIFY(sb.lineAt(0, 2, out.data()));

QCOMPARE(out[0].chars[0], 1020u);

QVERIFY(sb.lineAt(2, 2, out.data()));

QCOMPARE(out[0].chars[0], 1040u);

}

void TestScrollbackBuffer::popLine_takesMostRecent()

{

ScrollbackBuffer sb(10);

sb.pushLine(3, makeLine(3, 10).constData());

sb.pushLine(3, makeLine(3, 20).constData());

QVector<VTermScreenCell> out(3);

QVERIFY(sb.popLine(3, out.data()));

QCOMPARE(out[0].chars[0], 20u);

QCOMPARE(sb.size(), 1);

QVERIFY(sb.popLine(3, out.data()));

QCOMPARE(out[0].chars[0], 10u);

QCOMPARE(sb.size(), 0);

}

void TestScrollbackBuffer::popLine_emptyReturnsFalse()

{

ScrollbackBuffer sb(10);

QVector<VTermScreenCell> out(3);

QVERIFY(!sb.popLine(3, out.data()));

}

void TestScrollbackBuffer::popLine_intoNarrowerCols_truncates()

{

ScrollbackBuffer sb(10);

sb.pushLine(8, makeLine(8, 1).constData()); // chars 1..8 (tag 1)

QVector<VTermScreenCell> out(3);

QVERIFY(sb.popLine(3, out.data()));

QCOMPARE(out[0].chars[0], 1u);

QCOMPARE(out[1].chars[0], 2u);

QCOMPARE(out[2].chars[0], 3u);

}

void TestScrollbackBuffer::popLine_intoWiderCols_padsBlankCells()

{

ScrollbackBuffer sb(10);

sb.pushLine(3, makeLine(3, 1).constData()); // chars 1..3

QVector<VTermScreenCell> out(6);

// pre-fill out with sentinel so we can detect that pad cells were actually written.

for (int i = 0; i < 6; ++i) { out[i].chars[0] = 0xdeadbeef; }

QVERIFY(sb.popLine(6, out.data()));

QCOMPARE(out[0].chars[0], 1u);

QCOMPARE(out[2].chars[0], 3u);

QCOMPARE(out[3].chars[0], 0u); // blanked

QCOMPARE(out[5].chars[0], 0u); // blanked

}

void TestScrollbackBuffer::lineAt_outOfRange_returnsFalse()

{

ScrollbackBuffer sb(10);

sb.pushLine(3, makeLine(3, 1).constData());

QVector<VTermScreenCell> out(3);

QVERIFY(!sb.lineAt(-1, 3, out.data()));

QVERIFY(!sb.lineAt(1, 3, out.data())); // only index 0 exists

QVERIFY(!sb.lineAt(100, 3, out.data()));

}

void TestScrollbackBuffer::lineAt_returnsByHistoryIndex()

{

ScrollbackBuffer sb(10);

for (uint32_t i = 0; i < 4; ++i) {

sb.pushLine(2, makeLine(2, 100u + i * 10).constData());

}

QVector<VTermScreenCell> out(2);

QVERIFY(sb.lineAt(0, 2, out.data()));

QCOMPARE(out[0].chars[0], 100u);

QVERIFY(sb.lineAt(3, 2, out.data()));

QCOMPARE(out[0].chars[0], 130u);

}

void TestScrollbackBuffer::lineAt_intoWiderCols_padsBlankCells()

{

ScrollbackBuffer sb(10);

sb.pushLine(2, makeLine(2, 7).constData()); // chars 7..8

QVector<VTermScreenCell> out(5);

for (int i = 0; i < 5; ++i) { out[i].chars[0] = 0xcafef00d; }

QVERIFY(sb.lineAt(0, 5, out.data()));

QCOMPARE(out[0].chars[0], 7u);

QCOMPARE(out[1].chars[0], 8u);

QCOMPARE(out[2].chars[0], 0u);

QCOMPARE(out[4].chars[0], 0u);

}

void TestScrollbackBuffer::lineAt_intoNarrowerCols_truncates()

{

ScrollbackBuffer sb(10);

sb.pushLine(6, makeLine(6, 1).constData()); // chars 1..6

QVector<VTermScreenCell> out(2);

QVERIFY(sb.lineAt(0, 2, out.data()));

QCOMPARE(out[0].chars[0], 1u);

QCOMPARE(out[1].chars[0], 2u);

}

void TestScrollbackBuffer::clear_emptiesBuffer()

{

ScrollbackBuffer sb(10);

sb.pushLine(2, makeLine(2, 1).constData());

sb.pushLine(2, makeLine(2, 2).constData());

QCOMPARE(sb.size(), 2);

sb.clear();

QCOMPARE(sb.size(), 0);

QVERIFY(sb.isEmpty());

}

void TestScrollbackBuffer::setMaxLines_shrinks_dropsOldest()

{

ScrollbackBuffer sb(10);

for (uint32_t i = 0; i < 6; ++i) {

sb.pushLine(2, makeLine(2, 100u + i * 10).constData());

}

QCOMPARE(sb.size(), 6);

sb.setMaxLines(3);

QCOMPARE(sb.size(), 3);

QCOMPARE(sb.maxLines(), 3);

// Oldest remaining should be the 4th push (tag 130), most recent the 6th (tag 150).

QVector<VTermScreenCell> out(2);

QVERIFY(sb.lineAt(0, 2, out.data()));

QCOMPARE(out[0].chars[0], 130u);

QVERIFY(sb.lineAt(2, 2, out.data()));

QCOMPARE(out[0].chars[0], 150u);

}

void TestScrollbackBuffer::pushLine_returnsEvictionCount()

{

ScrollbackBuffer sb(3);

const auto row = makeLine(2, 1u);

QCOMPARE(sb.pushLine(2, row.constData()), 0);

QCOMPARE(sb.pushLine(2, row.constData()), 0);

QCOMPARE(sb.pushLine(2, row.constData()), 0); // now at cap

QCOMPARE(sb.pushLine(2, row.constData()), 1); // evicts oldest

QCOMPARE(sb.size(), 3);

QCOMPARE(sb.pushLine(2, row.constData()), 1);

QCOMPARE(sb.size(), 3);

QCOMPARE(sb.setMaxLines(1), 2);

QCOMPARE(sb.size(), 1);

QCOMPARE(sb.setMaxLines(10), 0);

}

QTEST_APPLESS_MAIN(TestScrollbackBuffer)

#include "test_scrollback_buffer.moc"