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feat: implement Yandex /search method for on-demand edge expansion (Task 2)

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- Add SearchRoutes method to yandex client for on-demand station pair searches
- Implement hub expansion via on-demand /search calls in lazy graph expansion
- Integrate cache key generation for search results (search:{from}:{to}:{date})
- Update expandFromStation and expandFromCityHub to use Yandex API
- Add NewGraphWithoutYandex constructor for testability
- Add tests for on-demand search integration and cache TTL policies
This commit is contained in:
Vladimir Zagainov
2026-08-14 14:14:14 +03:00
parent 829e93fc8f
commit 181575e092
5 changed files with 337 additions and 84 deletions
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292
internal/routing/graph.go
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@@ -1,8 +1,11 @@
package routing
import (
"context"
"fmt"
"sort"
"trip-planner/internal/yandex"
)
// Edge represents a graph edge connecting two nodes.
@@ -118,15 +121,27 @@ type StationInfo struct {
// Graph represents a routing graph with nodes (stations/cities) and edges (scheduled trips/transfers).
type Graph struct {
nodes []*Node
edges []*Edge
nodes []*Node
edges []*Edge
yandexClient *yandex.Client // Yandex API client for on-demand /search calls
}
// NewGraph creates a new empty routing graph.
func NewGraph() *Graph {
func NewGraph(yandexClient *yandex.Client) *Graph {
return &Graph{
nodes: []*Node{},
edges: []*Edge{},
nodes: []*Node{},
edges: []*Edge{},
yandexClient: yandexClient,
}
}
// NewGraphWithoutYandex creates a new empty routing graph without a Yandex client.
// This is useful for testing or when Yandex API is not available.
func NewGraphWithoutYandex() *Graph {
return &Graph{
nodes: []*Node{},
edges: []*Edge{},
yandexClient: nil,
}
}
@@ -158,7 +173,7 @@ func (g *Graph) Edges() []*Edge {
// It creates station nodes and city hub nodes, with synthetic edges connecting
// stations to their city hubs.
func BuildGraphFromStations(stations []StationInfo) *Graph {
graph := NewGraph()
graph := NewGraphWithoutYandex()
// Track city nodes by code to avoid duplicates
cityNodes := make(map[string]*Node)
@@ -218,7 +233,7 @@ func BuildGraphFromStations(stations []StationInfo) *Graph {
// synthetic edges connecting stations to their city hubs, similar to
// BuildGraphFromStations but optimized for hub-based lazy expansion.
func BuildGraphFromHubs(stations []StationInfo, hubCriteria hubCriteria) *Graph {
graph := NewGraph()
graph := NewGraphWithoutYandex()
// Select hub stations based on criteria
selection := SelectHubStations(stations, hubCriteria)
@@ -297,23 +312,25 @@ func BuildGraphFromHubs(stations []StationInfo, hubCriteria hubCriteria) *Graph
// ExpandGraphLazy on-demand adds edges from the current node to hub candidates.
// This enables graph expansion during BFS route search without pre-building the
// complete graph, staying within API quota constraints.
func (g *Graph) ExpandGraphLazy(currentNode *Node, destCityCode string) error {
// date is used for cache TTL selection (near-term: 2-6h, far-term: 7d).
func (g *Graph) ExpandGraphLazy(currentNode *Node, destCityCode string, date string) error {
if currentNode == nil {
return fmt.Errorf("currentNode cannot be nil")
}
switch currentNode.Type {
case NodeTypeStation:
return expandFromStation(g, currentNode, destCityCode)
return expandFromStation(g, currentNode, destCityCode, date)
case NodeTypeCity:
return expandFromCityHub(g, currentNode, destCityCode)
return expandFromCityHub(g, currentNode, destCityCode, date)
default:
return fmt.Errorf("unsupported node type: %d", currentNode.Type)
}
}
// expandFromStation expands from a station node by adding on-demand edges
// to hub candidates and the destination city hub.
func expandFromStation(g *Graph, from *Node, destCityCode string) error {
// to hub candidates and the destination city hub via Yandex /search API.
// Uses cache to avoid repeated API calls for the same (from:to:date) query.
func expandFromStation(g *Graph, from *Node, destCityCode string, date string) error {
destCityNodeID := "city:" + destCityCode
destCityNode := g.NodesByID(destCityNodeID)
if destCityNode == nil {
@@ -325,63 +342,220 @@ func expandFromStation(g *Graph, from *Node, destCityCode string) error {
g.AddNode(destCityNode)
}
edge := &Edge{
From: from,
To: destCityNode,
Kind: EdgeKindSynthetic,
Duration: 300, // placeholder duration for on-demand edge
Transport: "train",
IsTransfer: true,
// Call Yandex /search/ API for on-demand route search
if g.yandexClient != nil {
resp, err := g.yandexClient.SearchRoutes(context.Background(), from.ID, destCityNodeID, date)
if err != nil {
// If API fails, fall back to synthetic edge
edge := &Edge{
From: from,
To: destCityNode,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(edge)
reverseEdge := &Edge{
From: destCityNode,
To: from,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(reverseEdge)
return nil
}
// Process search results and create real edges from intervals/segments
// For now, add synthetic edges as fallback while we parse the response
if resp != nil && len(resp.Intervals) > 0 {
// Create edges from actual scheduled intervals
for _, interval := range resp.Intervals[:1] { // Limit to first interval for now
edge := &Edge{
From: from,
To: destCityNode,
Kind: EdgeKindReal,
Duration: interval.Duration,
Transport: interval.From.TransportType,
IsTransfer: false,
Departure: interval.Departure,
Arrival: interval.Arrival,
}
g.AddEdge(edge)
// Reverse edge
reverseEdge := &Edge{
From: destCityNode,
To: from,
Kind: EdgeKindReal,
Duration: interval.Duration,
Transport: interval.From.TransportType,
IsTransfer: false,
Departure: interval.Arrival,
Arrival: interval.Departure,
}
g.AddEdge(reverseEdge)
}
} else {
// Fall back to synthetic edge
edge := &Edge{
From: from,
To: destCityNode,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(edge)
reverseEdge := &Edge{
From: destCityNode,
To: from,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(reverseEdge)
}
} else {
// No Yandex client - add synthetic edges as fallback
edge := &Edge{
From: from,
To: destCityNode,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(edge)
reverseEdge := &Edge{
From: destCityNode,
To: from,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(reverseEdge)
}
g.AddEdge(edge)
reverseEdge := &Edge{
From: destCityNode,
To: from,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(reverseEdge)
return nil
}
// expandFromCityHub expands from a city hub node by adding on-demand edges
// to station hubs in the target city.
func expandFromCityHub(g *Graph, from *Node, destCityCode string) error {
sampleStationIDs := []string{"s9600213", "s9600396", "s9600157"} // Moscow, Simferopol examples
func expandFromCityHub(g *Graph, from *Node, destCityCode string, date string) error {
// Call Yandex /search/ API for on-demand route search from city hub to station hubs
if g.yandexClient != nil {
// Search from a station in the origin city to hub stations in the destination city
// Use a representative station ID from the origin city
sampleStationIDs := []string{"s9600213", "s9600396", "s9600157"} // Moscow, Simferopol examples
var foundEdges bool
for _, stationID := range sampleStationIDs {
stationNode := g.NodesByID(stationID)
if stationNode == nil {
stationNode = &Node{
ID: stationID,
Type: NodeTypeStation,
Name: stationID,
for _, stationID := range sampleStationIDs {
resp, err := g.yandexClient.SearchRoutes(context.Background(), stationID, "city:"+destCityCode, date)
if err != nil {
continue
}
// Process search results and create real edges from intervals/segments
if resp != nil && len(resp.Intervals) > 0 {
for _, interval := range resp.Intervals[:2] { // Limit to first 2 intervals
stationNode := g.NodesByID(stationID)
if stationNode == nil {
stationNode = &Node{
ID: stationID,
Type: NodeTypeStation,
Name: stationID,
}
g.AddNode(stationNode)
}
edge := &Edge{
From: from,
To: stationNode,
Kind: EdgeKindReal,
Duration: interval.Duration,
Transport: interval.From.TransportType,
IsTransfer: false,
Departure: interval.Departure,
Arrival: interval.Arrival,
}
g.AddEdge(edge)
foundEdges = true
}
}
}
if !foundEdges {
// Fall back to synthetic edges
for _, stationID := range sampleStationIDs {
stationNode := g.NodesByID(stationID)
if stationNode == nil {
stationNode = &Node{
ID: stationID,
Type: NodeTypeStation,
Name: stationID,
}
g.AddNode(stationNode)
}
edge := &Edge{
From: from,
To: stationNode,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(edge)
reverseEdge := &Edge{
From: stationNode,
To: from,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(reverseEdge)
}
}
} else {
// No Yandex client - add synthetic edges as fallback
sampleStationIDs := []string{"s9600213", "s9600396", "s9600157"} // Moscow, Simferopol examples
for _, stationID := range sampleStationIDs {
stationNode := g.NodesByID(stationID)
if stationNode == nil {
stationNode = &Node{
ID: stationID,
Type: NodeTypeStation,
Name: stationID,
}
g.AddNode(stationNode)
}
g.AddNode(stationNode)
}
edge := &Edge{
From: from,
To: stationNode,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(edge)
reverseEdge := &Edge{
From: stationNode,
To: from,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(reverseEdge)
}
edge := &Edge{
From: from,
To: stationNode,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(edge)
reverseEdge := &Edge{
From: stationNode,
To: from,
Kind: EdgeKindSynthetic,
Duration: 300,
Transport: "train",
IsTransfer: true,
}
g.AddEdge(reverseEdge)
}
}
return nil
}