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var is = require('is');
var removeArticle = require('./removeArticle');
var insertArticle = require('./insertArticle');
/**
Returns a new summary, with the given article removed from its
origin level, and placed at the given target level.
@param {Summary} summary
@param {String|SummaryArticle} origin: level to remove
@param {String|SummaryArticle} target: the level where the article will be found
@return {Summary}
*/
function moveArticle(summary, origin, target) {
// Coerce to level
var originLevel = is.string(origin)? origin : origin.getLevel();
var targetLevel = is.string(target)? target : target.getLevel();
var article = summary.getByLevel(originLevel);
// Remove
var removed = removeArticle(summary, origin);
// Adjust targetLevel if removing impacted it
targetLevel = arrayToLevel(
shiftLevel(levelToArray(originLevel),
levelToArray(targetLevel)));
// Re-insert
return insertArticle(removed, target, article);
}
/**
@param {Array<Number>} removedLevel
@param {Array<Number>} level The level to udpate
@return {Array<Number>}
*/
function shiftLevel(removedLevel, level) {
if (level.length === 0) {
// `removedLevel` is under level, so no effect
return level;
} else if (removedLevel.length === 0) {
// Either `level` is a child of `removedLevel`... or they are equal
// This is undefined behavior.
return level;
}
var removedRoot = removedLevel[0];
var root = level[0];
var removedRest = removedLevel.slice(1);
var rest = level.slice(1);
if (removedRoot < root) {
// It will shift levels at this point. The rest is unchanged.
return Array.prototype.concat(root - 1, rest);
} else if (removedRoot === root) {
// Look deeper
return Array.prototype.concat(root, shiftLevel(removedRest, rest));
} else {
// No impact
return level;
}
}
/**
@param {String}
@return {Array<Number>}
*/
function levelToArray(l) {
return l.split('.').map(function (char) {
return parseInt(char, 10);
});
}
/**
@param {Array<Number>}
@return {String}
*/
function arrayToLevel(a) {
return a.join('.');
}
module.exports = moveArticle;
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