const nest = require('depnest')
const { h, Struct, Value, when, computed } = require('mutant')
const pull = require('pull-stream')
const next = require('pull-next-step')
const Scroller = require('pull-scroll')
const TextNodeSearcher = require('text-node-searcher')

exports.gives = nest('app.page.search')

exports.needs = nest({
  'app.html.filter': 'first',
  'app.html.scroller': 'first',
  'message.html.render': 'first',
  'sbot.pull.log': 'first',
  'sbot.pull.stream': 'first'
})

var whitespace = /\s+/

function andSearch (terms, inputs) {
  for (var i = 0; i < terms.length; i++) {
    var match = false
    for (var j = 0; j < inputs.length; j++) {
      if (terms[i].test(inputs[j])) match = true
    }
    // if a term was not matched by anything, filter this one
    if (!match) return false
  }
  return true
}

function searchFilter (terms) {
  return function (msg) {
    var c = msg && msg.value && msg.value.content
    return c && (
      msg.key === terms[0] ||
      andSearch(terms.map(function (term) {
        return new RegExp('\\b' + term + '\\b', 'i')
      }), [c.text, c.name, c.title])
    )
  }
}

function createOrRegExp (ary) {
  return new RegExp(ary.map(function (e) {
    return '\\b' + e + '\\b'
  }).join('|'), 'i')
}

function highlight (el, query) {
  var searcher = new TextNodeSearcher({container: el})
  searcher.query = query
  searcher.highlight()
  return el
}

function fallback (createReader) {
  var fallbackRead
  return function (read) {
    return function (abort, cb) {
      read(abort, function next (end, data) {
        if (end && createReader && (fallbackRead = createReader(end))) {
          createReader = null
          read = fallbackRead
          read(abort, next)
        } else {
          cb(end, data)
        }
      })
    }
  }
}

exports.create = function (api) {
  return nest('app.page.search', searchPage)

  function searchPage (location) {
    const query = location.query.trim()

    var queryTerms = query.split(whitespace)
    var matchesQuery = searchFilter(queryTerms)

    const search = Struct({
      isLinear: Value(false),
      linear: Struct({
        checked: Value(0)
      }),
      fulltext: Struct({
        isDone: Value(false)
      }),
      matches: Value(0)
    })
    const hasNoFulltextMatches = computed([search.fulltext.isDone, search.matches],
      (done, matches) => done && matches === 0)

    const searchHeader = h('Search', [
      h('header', h('h1', query)),
      when(search.isLinear,
        h('section.details', [
          h('div.searched', ['Searched: ', search.linear.checked]),
          h('div.matches', [search.matches, ' matches'])
        ]),
        h('section.details', [
          h('div.searched'),
          when(hasNoFulltextMatches, h('div.matches', 'No matches'))
        ])
      )
    ])
    const { filterMenu, filterDownThrough, filterUpThrough, resetFeed } = api.app.html.filter(draw)
    const { container, content } = api.app.html.scroller({ prepend: [searchHeader, filterMenu] })

    function renderMsg (msg) {
      var el = api.message.html.render(msg)
      highlight(el, createOrRegExp(queryTerms))
      return el
    }

    function draw () {
      resetFeed({ container, content })

      pull(
        api.sbot.pull.log({old: false}),
        pull.filter(matchesQuery),
        filterUpThrough(),
        Scroller(container, content, renderMsg, true, false)
      )

      pull(
        api.sbot.pull.stream(sbot => next(sbot.search.query, { query, limit: 500 })),
        fallback((err) => {
          if (err === true) {
            search.fulltext.isDone.set(true)
          } else if (/^no source/.test(err.message)) {
            search.isLinear.set(true)
            return pull(
              next(api.sbot.pull.log, {reverse: true, limit: 500, live: false}),
              pull.through(() => search.linear.checked.set(search.linear.checked() + 1)),
              pull.filter(matchesQuery)
            )
          }
        }),
        filterDownThrough(),
        pull.through(() => search.matches.set(search.matches() + 1)),
        Scroller(container, content, renderMsg, false, false)
      )
    }

    draw()

    container.title = '?' + query
    return container
  }
}