/* eslint-disable import/no-extraneous-dependencies */

const Input = require('postcss/lib/input');

const LessParser = require('./LessParser');
const LessStringifier = require('./LessStringifier');

module.exports = {
  parse(less, options) {
    const input = new Input(less, options);
    const parser = new LessParser(input);

    parser.parse();

    // To handle double-slash comments (`//`) we end up creating a new tokenizer
    // in certain cases (see `lib/nodes/inline-comment.js`). However, this means
    // that any following node in the AST will have incorrect start/end positions
    // on the `source` property. To fix that, we'll walk the AST and compute
    // updated positions for all nodes.
    parser.root.walk((node) => {
      const offset = input.css.lastIndexOf(node.source.input.css);

      if (offset === 0) {
        // Short circuit - this node was processed with the original tokenizer
        // and should therefore have correct position information.
        return;
      }

      // This ensures that the chunk of source we're processing corresponds
      // strictly to a terminal substring of the input CSS. This should always
      // be the case, but if it ever isn't, we prefer to fail instead of
      // producing potentially invalid output.
      // istanbul ignore next
      if (offset + node.source.input.css.length !== input.css.length) {
        throw new Error('Invalid state detected in postcss-less');
      }

      const newStartOffset = offset + node.source.start.offset;
      const newStartPosition = input.fromOffset(offset + node.source.start.offset);

      // eslint-disable-next-line no-param-reassign
      node.source.start = {
        offset: newStartOffset,
        line: newStartPosition.line,
        column: newStartPosition.col
      };

      // Not all nodes have an `end` property.
      if (node.source.end) {
        const newEndOffset = offset + node.source.end.offset;
        const newEndPosition = input.fromOffset(offset + node.source.end.offset);

        // eslint-disable-next-line no-param-reassign
        node.source.end = {
          offset: newEndOffset,
          line: newEndPosition.line,
          column: newEndPosition.col
        };
      }
    });

    return parser.root;
  },

  stringify(node, builder) {
    const stringifier = new LessStringifier(builder);
    stringifier.stringify(node);
  },

  nodeToString(node) {
    let result = '';

    module.exports.stringify(node, (bit) => {
      result += bit;
    });

    return result;
  }
};