const nest = require('depnest')
const ref = require('ssb-ref')
const { h, map } = require('mutant')

exports.needs = nest({
  'backlinks.obs.references': 'first',
  'message.obs': {
    name: 'first'
  },
  'profile.html.person': 'first',
  'intl.sync.i18n': 'first'
})

exports.gives = nest('message.html.references')

exports.create = function (api) {
  const i18n = api.intl.sync.i18n
  return nest('message.html.references', function (msg) {
    if (!ref.type(msg.key)) return []

    const references = api.backlinks.obs.references(msg)

    return [
      map(references, link => {
        return h('a.backlink', {
          href: link.id, title: link.id
        }, [
          h('strong', [
            api.profile.html.person(link.author), i18n(' referenced this message:')
          ]), ' ',
          api.message.obs.name(link.id)
        ])
      }, {
        // treat all items as immutable (mutant cannot detect this as they are objects)
        comparer: (a, b) => a === b
      })
    ]
  })
}