const _ = require('./lodash')
const Graph = require('./graph')

module.exports = {
  write: write,
  read: read
}

function write (g) {
  var json = {
    options: {
      directed: g.isDirected(),
      multigraph: g.isMultigraph(),
      compound: g.isCompound()
    },
    nodes: writeNodes(g),
    edges: writeEdges(g)
  }
  if (!_.isUndefined(g.graph())) {
    json.value = _.clone(g.graph())
  }
  return json
}

function writeNodes (g) {
  return _.map(g.nodes(), function (v) {
    const nodeValue = g.node(v)
    const parent = g.parent(v)
    const node = { v: v }
    if (!_.isUndefined(nodeValue)) {
      node.value = nodeValue
    }
    if (!_.isUndefined(parent)) {
      node.parent = parent
    }
    return node
  })
}

function writeEdges (g) {
  return _.map(g.edges(), function (e) {
    const edgeValue = g.edge(e)
    const edge = { v: e.v, w: e.w }
    if (!_.isUndefined(e.name)) {
      edge.name = e.name
    }
    if (!_.isUndefined(edgeValue)) {
      edge.value = edgeValue
    }
    return edge
  })
}

function read (json) {
  var g = new Graph(json.options).setGraph(json.value)
  _.each(json.nodes, function (entry) {
    g.setNode(entry.v, entry.value)
    if (entry.parent) {
      g.setParent(entry.v, entry.parent)
    }
  })
  _.each(json.edges, function (entry) {
    g.setEdge({ v: entry.v, w: entry.w, name: entry.name }, entry.value)
  })
  return g
}