const {assert} = require('chai');
let Parser; let JavaScript;

describe('Tree', () => {
  let parser; let tree;

  before(async () =>
    ({Parser, JavaScript} = await require('./helper')),
  );

  beforeEach(() => {
    parser = new Parser().setLanguage(JavaScript);
  });

  afterEach(() => {
    parser.delete();
    tree.delete();
  });

  describe('.edit', () => {
    let input; let edit;

    it('updates the positions of nodes', () => {
      input = 'abc + cde';
      tree = parser.parse(input);
      assert.equal(
        tree.rootNode.toString(),
        '(program (expression_statement (binary_expression left: (identifier) right: (identifier))))',
      );

      let sumNode = tree.rootNode.firstChild.firstChild;
      let variableNode1 = sumNode.firstChild;
      let variableNode2 = sumNode.lastChild;
      assert.equal(variableNode1.startIndex, 0);
      assert.equal(variableNode1.endIndex, 3);
      assert.equal(variableNode2.startIndex, 6);
      assert.equal(variableNode2.endIndex, 9);

      ([input, edit] = spliceInput(input, input.indexOf('bc'), 0, ' * '));
      assert.equal(input, 'a * bc + cde');
      tree.edit(edit);

      sumNode = tree.rootNode.firstChild.firstChild;
      variableNode1 = sumNode.firstChild;
      variableNode2 = sumNode.lastChild;
      assert.equal(variableNode1.startIndex, 0);
      assert.equal(variableNode1.endIndex, 6);
      assert.equal(variableNode2.startIndex, 9);
      assert.equal(variableNode2.endIndex, 12);

      tree = parser.parse(input, tree);
      assert.equal(
        tree.rootNode.toString(),
        '(program (expression_statement (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (identifier))))',
      );
    });

    it('handles non-ascii characters', () => {
      input = 'αβδ + cde';

      tree = parser.parse(input);
      assert.equal(
        tree.rootNode.toString(),
        '(program (expression_statement (binary_expression left: (identifier) right: (identifier))))',
      );

      let variableNode = tree.rootNode.firstChild.firstChild.lastChild;

      ([input, edit] = spliceInput(input, input.indexOf('δ'), 0, '👍 * '));
      assert.equal(input, 'αβ👍 * δ + cde');
      tree.edit(edit);

      variableNode = tree.rootNode.firstChild.firstChild.lastChild;
      assert.equal(variableNode.startIndex, input.indexOf('cde'));

      tree = parser.parse(input, tree);
      assert.equal(
        tree.rootNode.toString(),
        '(program (expression_statement (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (identifier))))',
      );
    });
  });

  describe('.getChangedRanges(previous)', () => {
    it('reports the ranges of text whose syntactic meaning has changed', () => {
      let sourceCode = 'abcdefg + hij';
      tree = parser.parse(sourceCode);

      assert.equal(
        tree.rootNode.toString(),
        '(program (expression_statement (binary_expression left: (identifier) right: (identifier))))',
      );

      sourceCode = 'abc + defg + hij';
      tree.edit({
        startIndex: 2,
        oldEndIndex: 2,
        newEndIndex: 5,
        startPosition: {row: 0, column: 2},
        oldEndPosition: {row: 0, column: 2},
        newEndPosition: {row: 0, column: 5},
      });

      const tree2 = parser.parse(sourceCode, tree);
      assert.equal(
        tree2.rootNode.toString(),
        '(program (expression_statement (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (identifier))))',
      );

      const ranges = tree.getChangedRanges(tree2);
      assert.deepEqual(ranges, [
        {
          startIndex: 0,
          endIndex: 'abc + defg'.length,
          startPosition: {row: 0, column: 0},
          endPosition: {row: 0, column: 'abc + defg'.length},
        },
      ]);

      tree2.delete();
    });

    it('throws an exception if the argument is not a tree', () => {
      tree = parser.parse('abcdefg + hij');

      assert.throws(() => {
        tree.getChangedRanges({});
      }, /Argument must be a Tree/);
    });
  });

  describe('.walk()', () => {
    let cursor;

    afterEach(() => {
      cursor.delete();
    });

    it('returns a cursor that can be used to walk the tree', () => {
      tree = parser.parse('a * b + c / d');
      cursor = tree.walk();

      assertCursorState(cursor, {
        nodeType: 'program',
        nodeIsNamed: true,
        startPosition: {row: 0, column: 0},
        endPosition: {row: 0, column: 13},
        startIndex: 0,
        endIndex: 13,
      });

      assert(cursor.gotoFirstChild());
      assertCursorState(cursor, {
        nodeType: 'expression_statement',
        nodeIsNamed: true,
        startPosition: {row: 0, column: 0},
        endPosition: {row: 0, column: 13},
        startIndex: 0,
        endIndex: 13,
      });

      assert(cursor.gotoFirstChild());
      assertCursorState(cursor, {
        nodeType: 'binary_expression',
        nodeIsNamed: true,
        startPosition: {row: 0, column: 0},
        endPosition: {row: 0, column: 13},
        startIndex: 0,
        endIndex: 13,
      });

      assert(cursor.gotoFirstChild());
      assertCursorState(cursor, {
        nodeType: 'binary_expression',
        nodeIsNamed: true,
        startPosition: {row: 0, column: 0},
        endPosition: {row: 0, column: 5},
        startIndex: 0,
        endIndex: 5,
      });

      assert(cursor.gotoFirstChild());
      assert.equal(cursor.nodeText, 'a');
      assertCursorState(cursor, {
        nodeType: 'identifier',
        nodeIsNamed: true,
        startPosition: {row: 0, column: 0},
        endPosition: {row: 0, column: 1},
        startIndex: 0,
        endIndex: 1,
      });

      assert(!cursor.gotoFirstChild());
      assert(cursor.gotoNextSibling());
      assert.equal(cursor.nodeText, '*');
      assertCursorState(cursor, {
        nodeType: '*',
        nodeIsNamed: false,
        startPosition: {row: 0, column: 2},
        endPosition: {row: 0, column: 3},
        startIndex: 2,
        endIndex: 3,
      });

      assert(cursor.gotoNextSibling());
      assert.equal(cursor.nodeText, 'b');
      assertCursorState(cursor, {
        nodeType: 'identifier',
        nodeIsNamed: true,
        startPosition: {row: 0, column: 4},
        endPosition: {row: 0, column: 5},
        startIndex: 4,
        endIndex: 5,
      });

      assert(!cursor.gotoNextSibling());
      assert(cursor.gotoParent());
      assertCursorState(cursor, {
        nodeType: 'binary_expression',
        nodeIsNamed: true,
        startPosition: {row: 0, column: 0},
        endPosition: {row: 0, column: 5},
        startIndex: 0,
        endIndex: 5,
      });

      assert(cursor.gotoNextSibling());
      assertCursorState(cursor, {
        nodeType: '+',
        nodeIsNamed: false,
        startPosition: {row: 0, column: 6},
        endPosition: {row: 0, column: 7},
        startIndex: 6,
        endIndex: 7,
      });

      assert(cursor.gotoNextSibling());
      assertCursorState(cursor, {
        nodeType: 'binary_expression',
        nodeIsNamed: true,
        startPosition: {row: 0, column: 8},
        endPosition: {row: 0, column: 13},
        startIndex: 8,
        endIndex: 13,
      });

      const copy = tree.walk();
      copy.resetTo(cursor);

      assert(copy.gotoPreviousSibling());
      assertCursorState(copy, {
        nodeType: '+',
        nodeIsNamed: false,
        startPosition: {row: 0, column: 6},
        endPosition: {row: 0, column: 7},
        startIndex: 6,
        endIndex: 7,
      });

      assert(copy.gotoPreviousSibling());
      assertCursorState(copy, {
        nodeType: 'binary_expression',
        nodeIsNamed: true,
        startPosition: {row: 0, column: 0},
        endPosition: {row: 0, column: 5},
        startIndex: 0,
        endIndex: 5,
      });

      assert(copy.gotoLastChild());
      assertCursorState(copy, {
        nodeType: 'identifier',
        nodeIsNamed: true,
        startPosition: {row: 0, column: 4},
        endPosition: {row: 0, column: 5},
        startIndex: 4,
        endIndex: 5,
      });

      assert(copy.gotoParent());
      assert(copy.gotoParent());
      assert.equal(copy.nodeType, 'binary_expression');
      assert(copy.gotoParent());
      assert.equal(copy.nodeType, 'expression_statement');
      assert(copy.gotoParent());
      assert.equal(copy.nodeType, 'program');
      assert(!copy.gotoParent());

      assert(cursor.gotoParent());
      assert.equal(cursor.nodeType, 'binary_expression');
      assert(cursor.gotoParent());
      assert.equal(cursor.nodeType, 'expression_statement');
      assert(cursor.gotoParent());
      assert.equal(cursor.nodeType, 'program');
      assert(!cursor.gotoParent());
    });

    it('keeps track of the field name associated with each node', () => {
      tree = parser.parse('a.b();');
      cursor = tree.walk();
      cursor.gotoFirstChild();
      cursor.gotoFirstChild();

      assert.equal(cursor.currentNode.type, 'call_expression');
      assert.equal(cursor.currentFieldName, null);

      cursor.gotoFirstChild();
      assert.equal(cursor.currentNode.type, 'member_expression');
      assert.equal(cursor.currentFieldName, 'function');

      cursor.gotoFirstChild();
      assert.equal(cursor.currentNode.type, 'identifier');
      assert.equal(cursor.currentFieldName, 'object');

      cursor.gotoNextSibling();
      cursor.gotoNextSibling();
      assert.equal(cursor.currentNode.type, 'property_identifier');
      assert.equal(cursor.currentFieldName, 'property');

      cursor.gotoParent();
      cursor.gotoNextSibling();
      assert.equal(cursor.currentNode.type, 'arguments');
      assert.equal(cursor.currentFieldName, 'arguments');
    });

    it('returns a cursor that can be reset anywhere in the tree', () => {
      tree = parser.parse('a * b + c / d');
      cursor = tree.walk();
      const root = tree.rootNode.firstChild;

      cursor.reset(root.firstChild.firstChild);
      assertCursorState(cursor, {
        nodeType: 'binary_expression',
        nodeIsNamed: true,
        startPosition: {row: 0, column: 0},
        endPosition: {row: 0, column: 5},
        startIndex: 0,
        endIndex: 5,
      });

      cursor.gotoFirstChild();
      assertCursorState(cursor, {
        nodeType: 'identifier',
        nodeIsNamed: true,
        startPosition: {row: 0, column: 0},
        endPosition: {row: 0, column: 1},
        startIndex: 0,
        endIndex: 1,
      });

      assert(cursor.gotoParent());
      assert(!cursor.gotoParent());
    });
  });

  describe('.copy', () => {
    it('creates another tree that remains stable if the original tree is edited', () => {
      input = 'abc + cde';
      tree = parser.parse(input);
      assert.equal(
        tree.rootNode.toString(),
        '(program (expression_statement (binary_expression left: (identifier) right: (identifier))))',
      );

      const tree2 = tree.copy();
      [input, edit] = spliceInput(input, 3, 0, '123');
      assert.equal(input, 'abc123 + cde');
      tree.edit(edit);

      const leftNode = tree.rootNode.firstChild.firstChild.firstChild;
      const leftNode2 = tree2.rootNode.firstChild.firstChild.firstChild;
      const rightNode = tree.rootNode.firstChild.firstChild.lastChild;
      const rightNode2 = tree2.rootNode.firstChild.firstChild.lastChild;
      assert.equal(leftNode.endIndex, 6);
      assert.equal(leftNode2.endIndex, 3);
      assert.equal(rightNode.startIndex, 9);
      assert.equal(rightNode2.startIndex, 6);
    });
  });
});

function spliceInput(input, startIndex, lengthRemoved, newText) {
  const oldEndIndex = startIndex + lengthRemoved;
  const newEndIndex = startIndex + newText.length;
  const startPosition = getExtent(input.slice(0, startIndex));
  const oldEndPosition = getExtent(input.slice(0, oldEndIndex));
  input = input.slice(0, startIndex) + newText + input.slice(oldEndIndex);
  const newEndPosition = getExtent(input.slice(0, newEndIndex));
  return [
    input,
    {
      startIndex, startPosition,
      oldEndIndex, oldEndPosition,
      newEndIndex, newEndPosition,
    },
  ];
}

// Gets the extent of the text in terms of zero-based row and column numbers.
function getExtent(text) {
  let row = 0;
  let index = -1;
  let lastIndex = 0;
  while ((index = text.indexOf('\n', index + 1)) !== -1) {
    row++;
    lastIndex = index + 1;
  }
  return {row, column: text.length - lastIndex};
}

function assertCursorState(cursor, params) {
  assert.equal(cursor.nodeType, params.nodeType);
  assert.equal(cursor.nodeIsNamed, params.nodeIsNamed);
  assert.deepEqual(cursor.startPosition, params.startPosition);
  assert.deepEqual(cursor.endPosition, params.endPosition);
  assert.deepEqual(cursor.startIndex, params.startIndex);
  assert.deepEqual(cursor.endIndex, params.endIndex);

  const node = cursor.currentNode;
  assert.equal(node.type, params.nodeType);
  assert.equal(node.isNamed, params.nodeIsNamed);
  assert.deepEqual(node.startPosition, params.startPosition);
  assert.deepEqual(node.endPosition, params.endPosition);
  assert.deepEqual(node.startIndex, params.startIndex);
  assert.deepEqual(node.endIndex, params.endIndex);
}