var pull = require('pull-stream')
var ref = require('ssb-ref')
var hash = require('ssb-keys/util').hash
var markdown = require('ssb-markdown')

function isString (s) {
  return 'string' == typeof s
}

function update (state, msg) {
  if(msg.content.type === 'channel') {
    if(msg.content.subscribed)
      state.channels[msg.content.channel] = msg.content.irc || msg.content.channel
    else
      delete state.channels[msg.content.channel]
  }
  else if(msg.content.type === 'about' && ref.isFeed(msg.content.about) && (msg.content.name || msg.content.irc != null)) {
    state.users[msg.content.about] = msg.content.irc == null ? msg.content.name : msg.content.irc
  }
  return state
}

function init(sbot, id, cb) {
  var state = {users: {}, channels: {}}, int, called

  //hack since createUserStream doesn't supply sync: correctly.
  pull(
    sbot.createUserStream({id: id, limit: 1, reverse: true}),
    pull.collect(function (err, ary) {
      pull(
        sbot.createHistoryStream({id: id || sbot.id, live: true}),
        pull.drain(function (msg) {
          state = update(state, msg.value)
          if(msg.timestamp === ary[0].timestamp)
            cb && cb(null, state)
        })
      )
    })
  )

  return state
}

exports.init = init

function toKey(fn) {
  return function (state, msg) {
    var key
    if(msg.key) {
      key = msg.key
      msg = msg.value
    }
    else
      key = '%'+hash(JSON.stringify(msg, null, 2))
    return fn(state, msg, key)
  }
}

exports.isChannelPost = toKey(function isChannelPost (state, msg, key) {
  if(state.channels[msg.content.channel] && !msg.content.root) {
    var text = msg.content.text
    if(isString(text) && text) {
      text = text.split('\n')
      if(text.length > 1)
        text = text[0]
      else
        text = text[0]

      return [{
        author: msg.author,
        target: msg.content.channel,
        text: text.length > 100 ? text.substring(0, 97)+'...' : text,
        id: key,
        type: 'channel'
      }]
    }
  }
})

function uniq (a) {
  var b = []
  for(var i = 0; i < a.length; i++)
    if(!~b.indexOf(a[i])) b.push(a[i])
  return b
}

function getChannel(state, name) {
  name = name.replace(/^#/,'')
  return state.channels[name] === true ? name : state.channels[name]
}

function surrounding(text, match, length) {
  var i = Math.max(text.indexOf(match)-100, 0)
  return (i > 0 ? '...' : '') + text.substring(i, i+100) + (i + 100 < text.length ? '...' : '')
}

exports.isChannelMention = toKey(function (state, msg, key) {
  var text = msg.content.text
  if(isString(text) && text) {
    text = markdown.inline(text)
    if(!/(#\w+)/.test(text)) return []

    var m = uniq(text.match(/(#\w+)/g))
    return m.filter(function (name) {
      return getChannel(state, name)
    }).map(function (name) {
      return {
        author: msg.author,
        target: getChannel(state, name),
        text: surrounding(text, name, 100),
        id: key,
        type: 'channel'
      }
    })
  }
  return []
})

exports.isUserMention = toKey(function (state, msg, key) {
  var text = msg.content.text
  if(isString(text) && text && Array.isArray(msg.content.mentions)) {
    text = markdown.inline(text)
    return msg.content.mentions.filter(function (mention) {
      return state.users[mention.link]
    }).map(function (mention) {
        return {
          author: msg.author,
          target: state.users[mention.link],
          text: surrounding(markdown.inline(text), '@'+mention.name, 100),
          id: key,
          type: 'user'
        }
    })
  }
})

exports.isUserFollow = toKey(function (state, msg, key) {
  if(msg.content.type == 'contact' && msg.content.following && state.users[msg.content.contact])
    return {
      author: msg.author,
      target: state.users[msg.content.contact],
      text: 'followed you', //this will make sense since the notification will be a direct message
      id: key,
      type: 'user'
    }
})

exports.tests = [
  exports.isChannelPost,
  exports.isChannelMention,
  exports.isUserMention,
  exports.isUserFollow
]

exports.match = function (state, msg) {
  return exports.tests.reduce(function (found, test) {
    return found.concat(test(state, msg) || [])
  }, [])

}

exports.render = function (note, link) {
  //personal mentions are just cluttered with the target and action
  //since it's only shown to one person it's implied.
  if(note.target[0] !== '#')
    return note.author + ':' + note.text + (link ? (' ' + link) : '')

  return (
    [note.author, note.action, note.target].join(' ') + ': ' +
    note.text + ' ' +
    (link || '')
  )
}

exports.link = function (id, config) {
  return ((config && config.irc && config.irc.domain) || "http://viewer.scuttlebot.io") + '/' + encodeURIComponent(id)
}

//if(!module.parent) {
//  //this is just for testing...
//  require('ssb-client')(function (err, sbot) {
//    if(err) throw err
//    var state = init(sbot, process.argv[2] || sbot.id, function (err, state) {
//
//      console.log(state)
//      //XXX: properly persist state with a flumeview?
//
//      pull(
//        sbot.createLogStream({}),
//        pull.drain(function (msg) {
//          if(msg.sync) return
//          var a = tests.reduce(function (found, test) {
//            return found.concat(exports.match(state, msg) || [])
//          }, [])
//          if(a.length) {
//
//          }
//        })
//      )
//    })
//  })
//}
//