/**
 * @author Titus Wormer
 * @copyright 2015 Titus Wormer
 * @license MIT
 * @module remark:parse:util:remove-indentation
 * @fileoverview Remove indentation.
 */

'use strict';

/* Dependencies. */
var trim = require('trim');
var repeat = require('repeat-string');
var getIndent = require('./get-indentation');

/* Expose. */
module.exports = indentation;

/* Characters. */
var C_SPACE = ' ';
var C_NEWLINE = '\n';
var C_TAB = '\t';

/**
 * Remove the minimum indent from every line in `value`.
 * Supports both tab, spaced, and mixed indentation (as
 * well as possible).
 *
 * @example
 *   removeIndentation('  foo'); // 'foo'
 *   removeIndentation('    foo', 2); // '  foo'
 *   removeIndentation('\tfoo', 2); // '  foo'
 *   removeIndentation('  foo\n bar'); // ' foo\n bar'
 *
 * @param {string} value - Value to trim.
 * @param {number?} [maximum] - Maximum indentation
 *   to remove.
 * @return {string} - Unindented `value`.
 */
function indentation(value, maximum) {
  var values = value.split(C_NEWLINE);
  var position = values.length + 1;
  var minIndent = Infinity;
  var matrix = [];
  var index;
  var indentation;
  var stops;
  var padding;

  values.unshift(repeat(C_SPACE, maximum) + '!');

  while (position--) {
    indentation = getIndent(values[position]);

    matrix[position] = indentation.stops;

    if (trim(values[position]).length === 0) {
      continue;
    }

    if (indentation.indent) {
      if (indentation.indent > 0 && indentation.indent < minIndent) {
        minIndent = indentation.indent;
      }
    } else {
      minIndent = Infinity;

      break;
    }
  }

  if (minIndent !== Infinity) {
    position = values.length;

    while (position--) {
      stops = matrix[position];
      index = minIndent;

      while (index && !(index in stops)) {
        index--;
      }

      if (
        trim(values[position]).length !== 0 &&
        minIndent &&
        index !== minIndent
      ) {
        padding = C_TAB;
      } else {
        padding = '';
      }

      values[position] = padding + values[position].slice(
        index in stops ? stops[index] + 1 : 0
      );
    }
  }

  values.shift();

  return values.join(C_NEWLINE);
}