#include "UnitTest++/UnitTest++.h"

#include "TextEditor.hpp"

#include <cstdlib>
#include <cstring>
#include <string>

using namespace tp;

namespace {
	Input inputOf(const char* text) { return { text, Index(std::strlen(text)) }; }

	std::string contentsOf(const TextEditor& editor) {
		std::string out;
		for (auto iter = editor.begin(); iter != editor.end(); ++iter) {
			out += iter.character();
		}
		return out;
	}

	Pointer pointerAt(const std::string& text, size_t offset) {
		Pointer out;
		for (size_t idx = 0; idx < offset; idx++) {
			out += text[idx];
		}
		return out;
	}

	void placeCaret(TextEditor& editor, Pointer at) { editor.setCursorEnd(at); }

	void select(TextEditor& editor, Pointer from, Pointer to) {
		editor.setCursorEnd(to);
		editor.setCursor(from);
	}
}

SUITE(TextEditor) {
	TEST(EmptyEditorHasNoText) {
		TextEditor editor;

		CHECK_EQUAL("", contentsOf(editor));
		CHECK_EQUAL(0, editor.mNLines());
	}

	TEST(InsertIntoEmptyEditor) {
		TextEditor editor;

		editor.insert(inputOf("abc\nd"));

		CHECK_EQUAL("abc\nd", contentsOf(editor));
		CHECK(editor.getCursor() == Pointer(1, 1));
	}

	TEST(OriginalTextIsReadBack) {
		TextEditor editor(inputOf("hello\nworld"));

		CHECK_EQUAL("hello\nworld", contentsOf(editor));
		CHECK_EQUAL(1, editor.mNLines());
	}

	TEST(InsertAtStart) {
		TextEditor editor(inputOf("world"));

		placeCaret(editor, { 0, 0 });
		editor.insert(inputOf("hello "));

		CHECK_EQUAL("hello world", contentsOf(editor));
	}

	TEST(InsertAtEnd) {
		TextEditor editor(inputOf("hello"));

		placeCaret(editor, { 0, 5 });
		editor.insert(inputOf("\nworld"));

		CHECK_EQUAL("hello\nworld", contentsOf(editor));
		CHECK(editor.getCursor() == Pointer(1, 5));
	}

	TEST(InsertInTheMiddleSplitsPiece) {
		TextEditor editor(inputOf("hello\nworld"));

		placeCaret(editor, { 0, 2 });
		editor.insert(inputOf("XY"));

		CHECK_EQUAL("heXYllo\nworld", contentsOf(editor));
		CHECK(editor.getCursor() == Pointer(0, 4));
	}

	TEST(InsertOnSecondLine) {
		TextEditor editor(inputOf("hello\nworld"));

		placeCaret(editor, { 1, 3 });
		editor.insert(inputOf("-"));

		CHECK_EQUAL("hello\nwor-ld", contentsOf(editor));
	}

	TEST(TypingContinuesTheSamePiece) {
		TextEditor editor(inputOf("ab"));

		placeCaret(editor, { 0, 1 });
		editor.insert(inputOf("1"));
		editor.insert(inputOf("2"));
		editor.insert(inputOf("\n3"));

		CHECK_EQUAL("a12\n3b", contentsOf(editor));
		CHECK_EQUAL(1, editor.mNLines());
	}

	TEST(CaretIsClampedToLine) {
		TextEditor editor(inputOf("abc\nde"));

		placeCaret(editor, { 0, 100 });
		CHECK(editor.getCursor() == Pointer(0, 3));

		placeCaret(editor, { 100, 100 });
		CHECK(editor.getCursor() == Pointer(1, 2));
	}

	TEST(BackspaceRemovesPreviousCharacter) {
		TextEditor editor(inputOf("hello"));

		placeCaret(editor, { 0, 3 });
		editor.remove();

		CHECK_EQUAL("helo", contentsOf(editor));
		CHECK(editor.getCursor() == Pointer(0, 2));
	}

	TEST(BackspaceJoinsLines) {
		TextEditor editor(inputOf("hello\nworld"));

		placeCaret(editor, { 1, 0 });
		editor.remove();

		CHECK_EQUAL("helloworld", contentsOf(editor));
		CHECK(editor.getCursor() == Pointer(0, 5));
	}

	TEST(BackspaceAtStartDoesNothing) {
		TextEditor editor(inputOf("abc"));

		placeCaret(editor, { 0, 0 });
		editor.remove();

		CHECK_EQUAL("abc", contentsOf(editor));
	}

	TEST(DeleteRemovesNextCharacter) {
		TextEditor editor(inputOf("abc\ndef"));

		placeCaret(editor, { 0, 0 });
		editor.remove(false, TextEditor::RIGHT);
		CHECK_EQUAL("bc\ndef", contentsOf(editor));

		placeCaret(editor, { 0, 2 });
		editor.remove(false, TextEditor::RIGHT);
		CHECK_EQUAL("bcdef", contentsOf(editor));
	}

	TEST(DeleteAtEndDoesNothing) {
		TextEditor editor(inputOf("abc"));

		placeCaret(editor, { 0, 3 });
		editor.remove(false, TextEditor::RIGHT);

		CHECK_EQUAL("abc", contentsOf(editor));
	}

	TEST(SelectionRemovalAcrossPieces) {
		TextEditor editor(inputOf("0123456789"));

		placeCaret(editor, { 0, 5 });
		editor.insert(inputOf("abc"));
		CHECK_EQUAL("01234abc56789", contentsOf(editor));

		select(editor, { 0, 3 }, { 0, 10 });
		editor.remove(true);

		CHECK_EQUAL("012789", contentsOf(editor));
		CHECK(editor.getCursor() == Pointer(0, 3));
	}

	TEST(InsertReplacesSelection) {
		TextEditor editor(inputOf("one two three"));

		select(editor, { 0, 4 }, { 0, 7 });
		editor.insert(inputOf("2"));

		CHECK_EQUAL("one 2 three", contentsOf(editor));
	}

	TEST(RemoveEverything) {
		TextEditor editor(inputOf("ab\ncd"));

		select(editor, { 0, 0 }, { 1, 2 });
		editor.remove(true);

		CHECK_EQUAL("", contentsOf(editor));

		editor.insert(inputOf("x"));
		CHECK_EQUAL("x", contentsOf(editor));
	}

	TEST(ManyInsertionsKeepOrder) {
		TextEditor editor(inputOf("."));
		std::string expected = ".";

		for (int idx = 0; idx < 300; idx++) {
			const char letter[] = { char('a' + idx % 26), 0 };
			const size_t offset = (idx * 7) % (expected.size() + 1);

			placeCaret(editor, pointerAt(expected, offset));
			editor.insert(inputOf(letter));
			expected.insert(expected.begin() + offset, letter[0]);
		}

		CHECK_EQUAL(expected, contentsOf(editor));
	}

	TEST(RandomEditsMatchReferenceString) {
		const char* original = "first line\nsecond line\nthird";
		TextEditor editor(inputOf(original));
		std::string expected = original;
		const char* inserts[] = { "x", "yz", "\n", "a\nb", "long insertion" };

		std::srand(12345);

		for (int step = 0; step < 2000; step++) {
			const size_t offset = std::rand() % (expected.size() + 1);
			const int action = std::rand() % 3;

			if (action == 0 || expected.empty()) {
				const char* text = inserts[std::rand() % 5];
				placeCaret(editor, pointerAt(expected, offset));
				editor.insert(inputOf(text));
				expected.insert(offset, text);
			} else if (action == 1 && offset > 0) {
				placeCaret(editor, pointerAt(expected, offset));
				editor.remove();
				expected.erase(offset - 1, 1);
			} else {
				const size_t end = offset + std::rand() % 5;
				const size_t clampedEnd = end > expected.size() ? expected.size() : end;
				select(editor, pointerAt(expected, offset), pointerAt(expected, clampedEnd));
				editor.remove(true);
				expected.erase(offset, clampedEnd - offset);
			}

			if (contentsOf(editor) != expected) {
				CHECK_EQUAL(expected, contentsOf(editor));
				CHECK_EQUAL(-1, step);
				return;
			}
		}
	}
}

int main() { return UnitTest::RunAllTests(); }