OpenStreetBrowser/src/state.js

/* globals setPath, history */

var queryString = require('query-string')

function get () {
  var state = {}

  // repo
  if (global.mainRepo !== '') {
    state.repo = global.mainRepo
  }

  // path
  if (currentPath) {
    state.path = currentPath
  }

  // location
  if (typeof map.getZoom() !== 'undefined') {
    var center = map.getCenter().wrap()
    var zoom = map.getZoom()

    state.lat = center.lat
    state.lon = center.lng
    state.zoom = zoom
  }

  // other modules
  call_hooks('state-get', state)

  // done
  return state
}

function apply (state) {
  // path
  setPath(state.path, state)

  // location
  if (state.lat && state.lon && state.zoom) {
    if (typeof map.getZoom() === 'undefined') {
      map.setView({ lat: state.lat, lng: state.lon }, state.zoom)
    } else {
      map.flyTo({ lat: state.lat, lng: state.lon }, state.zoom)
    }
  }

  // other modules
  call_hooks('state-apply', state)
}

function stringify (state) {
  var link = ''

  if (!state) {
    state = get()
  }

  var tmpState = JSON.parse(JSON.stringify(state))

  // path
  if (state.path) {
    link += state.path
    delete tmpState.path
  }

  // location
  var locPrecision = 5
  if (state.zoom) {
    locPrecision =
      state.zoom > 16 ? 5
      : state.zoom > 8 ? 4
      : state.zoom > 4 ? 3
      : state.zoom > 2 ? 2
      : state.zoom > 1 ? 1
      : 0
  }

  if (state.zoom && state.lat && state.lon) {
    link += (link === '' ? '' : '&') + 'map=' +
      parseFloat(state.zoom).toFixed(0) + '/' +
      state.lat.toFixed(locPrecision) + '/' +
      state.lon.toFixed(locPrecision)

    delete tmpState.zoom
    delete tmpState.lat
    delete tmpState.lon
  }

  var newHash = queryString.stringify(tmpState)

  // Characters we dont's want escaped
  newHash = newHash.replace(/%2F/g, '/')
  newHash = newHash.replace(/%2C/g, ',')

  if (newHash !== '') {
    link += (link === '' ? '' : '&') + newHash
  }

  return link
}

function parse (link) {
  var firstEquals = link.search('=')
  var firstAmp = link.search('&')
  var urlNonPathPart = ''
  var newState = {}
  var newPath = ''

  if (link === '') {
    // nothing
  } else if (firstEquals === -1) {
    if (firstAmp === -1) {
      newPath = link
    } else {
      newPath = link.substr(0, firstAmp)
    }
  } else {
    if (firstAmp === -1) {
      urlNonPathPart = link
    } else if (firstAmp < firstEquals) {
      newPath = link.substr(0, firstAmp)
      urlNonPathPart = link.substr(firstAmp + 1)
    } else {
      urlNonPathPart = link
    }
  }

  newState = queryString.parse(urlNonPathPart)
  if (newPath !== '') {
    newState.path = newPath
  }

  if ('map' in newState) {
    var parts = newState.map.split('/')
    newState.zoom = parts[0]
    newState.lat = parts[1]
    newState.lon = parts[2]
    delete newState.map
  }

  return newState
}

function update (state, push) {
  if (!state) {
    state = get()
  }

  var newHash = '#' + stringify(state)

  call_hooks('state-update', state, newHash)

  if (push) {
    history.pushState(null, null, newHash)
    call_hooks('statePush', state, newHash)
  } else if (location.hash !== newHash && (location.hash !== '' || newHash !== '#')) {
    history.replaceState(null, null, newHash)
    call_hooks('stateReplace', state, newHash)
  }
}

module.exports = {
  get: get, // get the current app state
  apply: apply, // apply a state to the current app

  stringify: stringify, // create a link from a state (or the current state)
  parse: parse, // parse a state from a link

  update: update // update url (either replace or push)
}