const {uniqBy, intersection} = require('lodash');
const semver = require('semver');
const semverDiff = require('semver-diff');
const getLastRelease = require('./get-last-release');
const {makeTag, getLowerBound} = require('./utils');

/**
 * Find releases that have been merged from from a higher branch but not added on the channel of the current branch.
 *
 * @param {Object} context semantic-release context.
 *
 * @return {Array<Object>} Last release and next release to be added on the channel of the current branch.
 */
module.exports = context => {
  const {
    branch,
    branches,
    options: {tagFormat},
  } = context;

  const higherChannels = branches
    // Consider only releases of higher branches
    .slice(branches.findIndex(({name}) => name === branch.name) + 1)
    // Exclude prerelease branches
    .filter(({type}) => type !== 'prerelease')
    .map(({channel}) => channel);

  const versiontoAdd = uniqBy(
    branch.tags.filter(
      ({channels, version}) =>
        !channels.includes(branch.channel) &&
        intersection(channels, higherChannels).length > 0 &&
        (branch.type !== 'maintenance' || semver.gte(version, getLowerBound(branch.mergeRange)))
    ),
    'version'
  ).sort((a, b) => semver.compare(b.version, a.version))[0];

  if (versiontoAdd) {
    const {version, gitTag, channels} = versiontoAdd;
    const lastRelease = getLastRelease(context, {before: version});
    if (semver.gt(getLastRelease(context).version, version)) {
      return;
    }

    const type = lastRelease.version ? semverDiff(lastRelease.version, version) : 'major';
    const name = makeTag(tagFormat, version);
    return {
      lastRelease,
      currentRelease: {type, version, channels, gitTag, name, gitHead: gitTag},
      nextRelease: {
        type,
        version,
        channel: branch.channel,
        gitTag: makeTag(tagFormat, version, branch.channel),
        name,
        gitHead: gitTag,
      },
    };
  }
};