Oasis - Refactor package stationgraph to support charge station based graph

[CodeBear801]

This task is sub task of #231, and related with #241 and #242

background

• In the package of stationgraph, there are graph, node, edge

  • graph contains start, end, and connectivity which is represented by a group of nodes
  • graph implement dijkstra
  • node contains neighbors, for previous situation, all the connectivity is known when graph was built

• Here is how connectivity is generated for search along route for charge stations

  • Calculate a route from orig to dest
  • Identify the location which is needed for charging, such as, energy level is lower than a certain level
  • Take the location as center, create a query bounding box and search for near by charge stations
  • Calculate route between charge station pair of each location.
  • Construct graph, convert all information to node and its neighbors.

// simulate locations array contains 4 points: orig -> location1 -> location2 -> dest
// (1.1, 1.1) -> (2.2, 2.2) -> (3.3, 3.3) -> (4.4, 4.4)
// location1 will find 4 nearby charge stations
// location2 will find 2 nearby charge stations
// search service will provide results based on upper information.
// Table service will provide result for: 1(orig) -> 4(charge stations around location 1),
// 4(charge stations around location 1) -> 2(charge stations around location 2),
// 2(charge stations around location 2) -> 1(dest)
func TestCalculateWeightBetweenNeighbors(t *testing.T) {
...

• New requirements
  • connectivity is generated during running time, each node will generate thousands of connectivity, its impossible to pre-build graph at beginning.
  • need to adjust graph, to make which based on abstract of node and edges, not exact instance

[CodeBear801]

• Add interface of neighbors
  • Provide function getNeighbors
  • neighborsPreGenerated
  • neighborsBuildOnTheFly