import * as turfHelpers from '@turf/helpers';
import { TilePathParams, TilePathGroup, TileType } from './tiles';
import { existsSync, mkdirSync, open, createWriteStream, rmdirSync } from 'fs';
import { LevelUp } from 'levelup';
import { TileIndex } from './tile_index';
import { lonlatsToCoords } from './index';
import { SharedStreetsGeometry, SharedStreetsReference, RoadClass } from 'sharedstreets-types';
import { execSync } from 'child_process';
import length from '@turf/length';
import distance from '@turf/distance';
import envelope from '@turf/envelope';
import lineSliceAlong from '@turf/line-slice-along';
import along from '@turf/along';
import bearing from '@turf/bearing';
import nearestPointOnLine from '@turf/nearest-point-on-line';

const { exec } = require('child_process');
const OSRM = require("osrm");
const xml = require('xml');
const stream = require('stream');
const levelup = require('levelup');
const leveldown = require('leveldown');
const chalk = require('chalk');
const path = require('path');
const util = require('util');
import * as fs from "fs";
import Match from './commands/match';
import { rmse, resolveHome } from './util';
import { LineString } from '@turf/buffer/node_modules/@turf/helpers';

const uuidHash = require('uuid-by-string');
const nodeModules = require('global-modules');
const yarnModules = require('yarn-global')


const DEFAULT_SEARCH_RADIUS = 10;
const MIN_CONFIDENCE = 0.5;
const OPTIMIZE_GRAPH = true;
const USE_LOCAL_CACHE = true;
const SHST_GRAPH_CACHE_DIR = resolveHome('~/.shst/cache/graphs/');


function getOSRMDirectory() {
    if(fs.existsSync('node_modules/osrm/')) {
        return  'node_modules/osrm/';
    }
    else if(fs.existsSync(path.join(nodeModules, 'osrm/'))) {
        return path.join(nodeModules, 'osrm/');
    }
    else if(fs.existsSync(path.join(yarnModules.getDirectory(), 'osrm/'))) {
        return path.join(yarnModules.getDirectory(), 'osrm/');
    }
    else {
        return null
    }
}

const OSRM_DIR = getOSRMDirectory();

export enum MatchType {
    DIRECT = 'direct',
    HMM = 'hmm'
}

export enum GraphMode {
    CAR_ALL = 'car_all',
    CAR_SURFACE_ONLY = 'car_surface_only',
    CAR_MOTORWAY_ONLY = 'car_motorway_only',
    BIKE = 'bike',
    PEDESTRIAN = 'ped'
}

// interface typecheck for SharedStreetsGeometry
function geomInstance(object: any): object is SharedStreetsGeometry {
    return 'forwardReferenceId' in object;
}

function getReferenceLength(ref:SharedStreetsReference) {
    var length = 0;
    for(var lr of ref.locationReferences) {
        if(lr.distanceToNextRef)
            length += lr.distanceToNextRef;
    }
    return length / 100;
}

const DEFAULT_LENGTH_TOLERANCE = 0.1;
const DEFUALT_CANDIDATES = 10;
const DEFAULT_BEARING_TOLERANCE  = 15; // 360 +/- tolerance

const MAX_FEATURE_LENGTH = 15000; // 1km

const MAX_SEARCH_RADIUS = 100;
const MAX_LENGTH_TOLERANCE = 0.5;
const MAX_CANDIDATES = 10;
const MAX_BEARING_TOLERANCE  = 180; // 360 +/- tolerance

const REFERNECE_GEOMETRY_OFFSET = 2;
const MAX_ROUTE_QUERIES = 16;

// TODO need to pull this from PBF enum defintion 

// @property {number} Motorway=0 Motorway value
//  * @property {number} Trunk=1 Trunk value
//  * @property {number} Primary=2 Primary value
//  * @property {number} Secondary=3 Secondary value
//  * @property {number} Tertiary=4 Tertiary value
//  * @property {number} Residential=5 Residential value
//  * @property {number} Unclassified=6 Unclassified value
//  * @property {number} Service=7 Service value
//  * @property {number} Other=8 Other value

function roadClassConverter(roadClass:string):number {

	if(roadClass === 'Motorway')
		return 0;
	else if(roadClass === 'Trunk')
		return 1;
	else if(roadClass === 'Primary')
		return 2;
	else if(roadClass === 'Secondary')
		return 3;
	else if(roadClass === 'Tertiary')
		return 4;
	else if(roadClass === 'Residential')
		return 5;
	else if(roadClass === 'Unclassified')
		return 6;
	else if(roadClass === 'Service')
		return 7;
	else 
		return null;
}

function angleDelta(a1, a2) {

	var delta = 180 - Math.abs(Math.abs(a1 - a2) - 180); 
	return delta;

}

function normalizeAngle(a) {

	if(a < 0) 
		return a + 360;
	return a;

}

export enum ReferenceDirection {

	FORWARD = "forward",
	BACKWARD = "backward"

}

export enum ReferenceSideOfStreet {

	RIGHT = "right",
	LEFT = "left",
	UNKNOWN = "unknown"

}

interface SortableCanddate {

	score:number;
	calcScore():number;

}

export class PointCandidate implements SortableCanddate {

	score:number;
	
	searchPoint:turfHelpers.Feature<turfHelpers.Point>;
	pointOnLine:turfHelpers.Feature<turfHelpers.Point>;
	snappedPoint:turfHelpers.Feature<turfHelpers.Point>;

	geometryId:string;
	referenceId:string;
	roadClass:RoadClass;
	direction:ReferenceDirection;
	streetname:string;
	referenceLength:number;
	location:number;
	bearing:number;
	interceptAngle:number;
	sideOfStreet:ReferenceSideOfStreet;
	oneway:boolean;

	calcScore():number {
		
		if(!this.score) {
			// score for snapped points are average of distance to point on line distance and distance to snapped ponit
			if(this.snappedPoint)
				this.score = (this.pointOnLine.properties.dist + distance(this.searchPoint, this.snappedPoint, {units: 'meters'})) / 2;
			else
				this.score = this.pointOnLine.properties.dist;		
		}
		return this.score;
	}

	toFeature():turfHelpers.Feature<turfHelpers.Point> {

		this.calcScore();

		var feature:turfHelpers.Feature<turfHelpers.Point> = turfHelpers.feature(this.pointOnLine.geometry, {	

			score:			this.score,
			location: 		this.location,
			referenceLength: this.referenceLength,
			geometryId:		this.geometryId,
			referenceId:	this.referenceId,
			direction:		this.direction,
			bearing:		this.bearing,
			sideOfStreet: 	this.sideOfStreet,
			interceptAngle:	this.interceptAngle

		});

		return feature;
	}
}

class GraphNode {
    nodeId:number;
    shstIntersectionId:string;
}

class GraphEdge {
    edgeId:number;
    shstGeometryId:string;
}

class GraphNodeEdgeRelations {
    nodeId:number;
    edgeIds:number[];
}


export class PathSegment {

	referenceId:string;
	geometryId:string;
	roadClass:RoadClass;
	streetname:string;

	fromIntersectionId:string;
    toIntersectionId:string;

	fromStreetnames:string[];
	toStreetnames:string[];

	referenceLength:number;
	point:number;
	section:number[];
    direction:ReferenceDirection;

    geometry;
    
}

export class PathCandidate {

    matchType:MatchType;

    confidence:number;
	score:number;
	originalFeatureLength:number;
	pathLength:number;

	startPoint:PointCandidate;
	endPoint:PointCandidate;

	segments:PathSegment[];

	originalFeature:turfHelpers.Feature<turfHelpers.Geometry>;
	matchedPath:turfHelpers.Feature<turfHelpers.Geometry>;

	sideOfStreet:ReferenceSideOfStreet;


    toDebugView():turfHelpers.FeatureCollection<turfHelpers.Geometry> {

        var debugCollection = turfHelpers.featureCollection([this.originalFeature, this.matchedPath]);
        return debugCollection;

    }

	getOriginalFeatureLength() {

		if(!this.originalFeatureLength) 
			this.originalFeatureLength = length(this.originalFeature, {"units":"meters"});

		return this.originalFeatureLength;

	}

	getPathLength():number {

		if(!this.pathLength) {
			this.pathLength = 0;
			for(var segment of this.segments) {
				if(segment.section)
					this.pathLength = this.pathLength + (segment.section[1] - segment.section[0]);
				else 
					this.pathLength = this.pathLength + segment.referenceLength;
			}
		}

		return this.pathLength;

	}

	getLengthDelta():number {
		return this.getPathLength() - this.getOriginalFeatureLength();
	}

	isColinear(candidate:PathCandidate):boolean {

		if(this.segments.length > 0 && candidate.segments.length > 0 && this.segments.length == candidate.segments.length) {

			var path1GeometryIds:Set<string> = new Set();
			var path2GeometryIds:Set<string> = new Set();

			for(var segment of this.segments) {
				path1GeometryIds.add(segment.geometryId);				
			}

			for(var segment of candidate.segments) {
				path2GeometryIds.add(segment.geometryId);

				if(!path1GeometryIds.has(segment.geometryId))
					return false;				
			}

			for(var segment of this.segments) {
				if(!path2GeometryIds.has(segment.geometryId))
					return false;					
			}

		}
		else 
			return false; 

		return true;
    }

}


export class LevelDB {

    db;

    constructor(directory) {
        this.db = levelup(leveldown(directory));
    }

    async get(key:string):Promise<any> {
        try {
            var data = await this.db.get(key);
            return data.toString();
        }
        catch(error) {
            return null;
        }
    }

    async put(key:string, data:any) {
        return await this.db.put(key, data);
    }

    async has(key:string):Promise<boolean> {
        try {
            await this.db.get(key);
            return true;
        }
        catch(error) {
            return null;
        }
    }
}

function streamPromise(stream) {
    return new Promise((resolve, reject) => {
        stream.on('end', () => {
            resolve('end');
        });
        stream.on('error', (error) => {
            reject(error);
        });
    });
}

export class Graph {

    id:string;
    db:LevelDB;
    osrm;
    tilePathGroup:TilePathGroup;
    tileIndex:TileIndex;
    graphMode:GraphMode;

    // options
    searchRadius = DEFAULT_SEARCH_RADIUS;
    snapIntersections = false;
    useHMM = true;
    useDirect = true;
    bearingTolerance:number = DEFAULT_BEARING_TOLERANCE;
    tileParams;

    constructor(extent:turfHelpers.Feature<turfHelpers.Polygon>, tileParams:TilePathParams, graphMode:GraphMode=GraphMode.CAR_ALL, existingTileIndex:TileIndex=null, ) {

        this.tileParams = tileParams;
        this.tilePathGroup = TilePathGroup.fromPolygon(extent, 1000, tileParams);
        this.tilePathGroup.addType(TileType.GEOMETRY);
        this.tilePathGroup.addType(TileType.REFERENCE);

        this.graphMode = graphMode;

        var paths:string[] = [];
        for(var path of this.tilePathGroup) {
            paths.push(path.toPathString());
        }

        if(existingTileIndex) {
            this.tileIndex = existingTileIndex;
        }
        else {
            this.tileIndex = new TileIndex();
        }

        // create id from tile path hash  
        this.id = uuidHash(this.graphMode + ' node-pair.sv1 ' + paths.join(" "));
    }

    async createGraphXml() {

        // build xml representation of graph + leveldb id map
        var graphPath = path.join(SHST_GRAPH_CACHE_DIR, this.id);

        var nextNodeId:number = 1;
        var nextEdgeId:number = 1;
        var xmlPath = path.join(graphPath, '/graph.xml');

        // create xml stream
        const pipeline = util.promisify(stream.pipeline);
        var xmlStreamWriter = createWriteStream(xmlPath);

        var osmRootElem = xml.element({ _attr: { version: '0.6', generator: 'shst cli v1.0'} });
       
        var xmlStream = xml({ osm: osmRootElem }, { stream: true });
        xmlStream.on('data', function (chunk) {xmlStreamWriter.write(chunk)});
    
        const writeNode = async (lon:number, lat:number, shstIntersectionId:string=null):Promise<number> => {
            var nodeId:number;

            // check if intersection node already written
            if(shstIntersectionId && await this.db.has(shstIntersectionId)) {
                var node:GraphNode =  JSON.parse(await this.db.get(shstIntersectionId));
                nodeId = node.nodeId;
            }
            else {

                nodeId = nextNodeId;
            
                var newNode:GraphNode = new GraphNode();
                newNode.nodeId = nodeId;

                if(shstIntersectionId) {
                    newNode.shstIntersectionId = shstIntersectionId;
                    await this.db.put(shstIntersectionId, JSON.stringify(newNode));
                }
                
                await this.db.put('node:' + nodeId, JSON.stringify(newNode));

                // write node xml
                osmRootElem.push({ node: [{_attr:{id:nodeId, lat:lat, lon:lon}}] });
                nextNodeId++;
            }
            
            return nodeId;
        };

        const pushNodePair = async (nodePairId, refId) => {
            if(await this.db.has(nodePairId)) {
                var existingEdges = JSON.parse(await this.db.get(nodePairId));
                existingEdges.push(refId)
                await this.db.put(nodePairId, JSON.stringify(existingEdges));
            }
            else {
                await this.db.put(nodePairId, JSON.stringify([refId]));
            }
        }        

        for(var obj of this.tileIndex.objectIndex.values()) {

            if(geomInstance(obj)) {

                if(obj.roadClass == 'Motorway') {
                    if(this.graphMode != GraphMode.CAR_ALL && this.graphMode != GraphMode.CAR_MOTORWAY_ONLY) {
                        continue;
                    }
                } 
                else {
                    if(this.graphMode == GraphMode.CAR_MOTORWAY_ONLY) {
                        continue;
                    }
                }

                if(obj.roadClass == 'Other') {
                    if(this.graphMode != GraphMode.BIKE && this.graphMode != GraphMode.PEDESTRIAN) {
                        continue;
                    }
                }

                // iterate through coordinates and build nodes
                var coords:number[][] = lonlatsToCoords(obj.lonlats);
                var nodeIds = [];
                for(var i = 0; i < coords.length; i++) {

                    var shstIntersectionId = null;
                    if(i === 0)
                        shstIntersectionId = obj.fromIntersectionId;
                    else if(i === coords.length - 1)
                        shstIntersectionId = obj.toIntersectionId;

                    var nodeId = await writeNode(coords[i][0], coords[i][1], shstIntersectionId);
                    nodeIds.push(nodeId);

                }

                // var edge:GraphEdge = new GraphEdge();
                // edge.shstGeometryId = obj.id;
                // edge.edgeId = nextEdgeId;
                // await this.db.put(obj.id, JSON.stringify(edge));
                // await this.db.put('edge:' + edge.edgeId, JSON.stringify(edge));
            
                var nodeIdElems:{}[] = [];

                var previousNode = null;
                for(nodeId of nodeIds) {
                    
                    //var nodeEdgeRelation:GraphNodeEdgeRelations;
                    // if(await this.db.has('node-edges:' + nodeId)){
                    //     // insert new edge into existing node-edge relation set for node id
                    //     nodeEdgeRelation = JSON.parse(await this.db.get('node-edges:' + nodeId))
                    //     var edgeIds = new Set(nodeEdgeRelation.edgeIds);
                    //     edgeIds.add(edge.edgeId);
                    //     nodeEdgeRelation.edgeIds = [...edgeIds.values()];
                    // }
                    // else {
                    //      // create node-edge relation set for node id
                    //     nodeEdgeRelation = new GraphNodeEdgeRelations();
                    //     nodeEdgeRelation.nodeId = nodeId;
                    //     nodeEdgeRelation.edgeIds = [edge.edgeId];
                    // }

                    // await this.db.put('node-edges:' + nodeId, JSON.stringify(nodeEdgeRelation));
                    nodeIdElems.push({nd:[{_attr:{ref:nodeId}}]});

                    if(previousNode) {
                        pushNodePair('node-pair:' + nodeId + '-' + previousNode, obj.forwardReferenceId);
                        if(obj.backReferenceId)
                            pushNodePair('node-pair:' + previousNode + '-' + nodeId , obj.backReferenceId);
                    }

                    previousNode = nodeId;
                }   
            
                var oneWay = obj.backReferenceId ? 'no' : 'yes';
                var roadClass = obj.roadClass.toLocaleLowerCase();

                if(roadClass == "other")
                    roadClass = "path"; // TODO add bike/ped modal restrictions to paths 

                osmRootElem.push({way:[{_attr:{id:nextEdgeId}},{tag:{_attr:{k:'highway', v:roadClass}}},{tag:{_attr:{k:'oneway', v:oneWay}}},...nodeIdElems]});

                nextEdgeId++;
            }
        }
          
        const writeFinished = new Promise((resolve, reject) => {
            xmlStreamWriter.on('finish', () => {  
                resolve(xmlPath);
            });
        });
        

        osmRootElem.close();
        xmlStreamWriter.close();
        //xmlStream.end();
      
        return writeFinished;
    }

    async buildGraph() {
        
        // check if graph is already built;
        if(this.osrm)
            return;
        try {
            var graphPath = path.join(SHST_GRAPH_CACHE_DIR, this.id);
            var dbPath = path.join(graphPath, '/db');

            await this.tileIndex.indexTilesByPathGroup(this.tilePathGroup)

            if(USE_LOCAL_CACHE && existsSync(dbPath)) {
                var osrmPath = path.join(graphPath, '/graph.xml.osrm');
                console.log(chalk.keyword('lightgreen')("     loading pre-built " + this.graphMode + " graph from: " + osrmPath));
                this.db = new LevelDB(dbPath);
                if(OPTIMIZE_GRAPH)
                    this.osrm = new OSRM({path:osrmPath});
                else
                    this.osrm = new OSRM({path:osrmPath, algorithm:"MLD"});
            }
            else {
                
                if(!OSRM_DIR) {
                    console.log("unable to locate OSRM module.")
                    throw "unable to locate OSRM module."
                }
        
                
                // TODO before building, check if this graph is a subset of an existing graph
                console.log(chalk.keyword('lightgreen')("     building graph using OSRM from: " + OSRM_DIR));
                

                mkdirSync(dbPath, {recursive:true});
                this.db = new LevelDB(dbPath)

                console.log(chalk.keyword('lightgreen')("     building " + this.graphMode + " graph  xml..."));
                var xmlPath = await this.createGraphXml();

                //extract 
                console.log(chalk.keyword('lightgreen')("     building " + this.graphMode + " graph from: " + xmlPath));
                
                var profile;

                if(this.graphMode === GraphMode.CAR_ALL || this.graphMode === GraphMode.CAR_SURFACE_ONLY || this.graphMode === GraphMode.CAR_MOTORWAY_ONLY)
                    profile = path.join(OSRM_DIR, 'profiles/car.lua');
                else if(this.graphMode === GraphMode.BIKE)
                    profile = path.join(OSRM_DIR, 'profiles/bicycle.lua');
                else if(this.graphMode === GraphMode.PEDESTRIAN)
                    profile = path.join(OSRM_DIR, 'profiles/foot.lua');

                execSync(path.join(OSRM_DIR, 'lib/binding/osrm-extract') + ' ' + xmlPath + ' -p ' + profile);

                var osrmPath:any = xmlPath + '.osrm';

                if(OPTIMIZE_GRAPH) {
                    console.log(chalk.keyword('lightgreen')("     optimizing graph..."));
                    execSync(path.join(OSRM_DIR, 'lib/binding/osrm-contract') + ' ' + osrmPath);
                    this.osrm = new OSRM({path:osrmPath});
                }
                else {
                    execSync(path.join(OSRM_DIR, 'lib/binding/osrm-partition') + ' ' + osrmPath);
                    execSync(path.join(OSRM_DIR, 'lib/binding/osrm-customize') + ' ' + osrmPath);
                    console.log(chalk.keyword('lightgreen')("     skipping graph optimization..."));
                    this.osrm = new OSRM({path:osrmPath, algorithm:"MLD"});
                }
            }
        }
        catch(e) {
            console.log("Unable to build graph: " + e);
            console.log("Try deleting existing cached graph: " + graphPath);
        }
    }

    async matchTrace(feature:turfHelpers.Feature<turfHelpers.LineString>) {

              // fall back to hmm for probabilistic path discovery
            if(!this.osrm)
                throw "Graph not buit. call buildGraph() before running queries."
            
            var hmmOptions = {
                coordinates: feature.geometry.coordinates,
                annotations: true,
                geometries: 'geojson',
                radiuses: Array(feature.geometry.coordinates.length).fill(this.searchRadius)
            };

            try {
                var matches = await new Promise((resolve, reject) => {
                    this.osrm.match(hmmOptions, function(err, response) {
                        if (err) 
                            reject(err);
                        else
                            resolve(response)
                    });
                });

                var visitedEdges:Set<string> = new Set();
                var visitedEdgeList:string[] = [];

                if(matches['matchings'] &&  matches['matchings'].length > 0) {
                    
                    var match = matches['matchings'][0];
                    if(0 < match.confidence ) {

                        // this is kind of convoluted due to the sparse info returned in the OSRM annotations...
                        // write out sequence of nodes and edges as emitted from walking OSRM-returned nodes
                        // finding the actual posistion and directionality of the OSRM-edge within the ShSt graph 
                        // edge means that we have to snap start/end points in the OSRM geom
                        
                        //console.log(JSON.stringify(match.geometry));

                        var edgeCandidates;
                        var nodes:number[] = [];
                        var visitedNodes:Set<number> = new Set();
                        // ooof this is brutual -- need to unpack legs and reduce list... 
                        for(var leg of match['legs']) {
                            //console.log(leg['annotation']['nodes'])
                            for(var n of leg['annotation']['nodes']){ 
                                if(!visitedNodes.has(n) || nodes.length == 0)
                                    nodes.push(n);

                                visitedNodes.add(n);
                            }
                        }

                    // then group node pairs into unique edges...
                        var previousNode = null;
                        for(var nodeId of nodes) {
                            if(await this.db.has('node:' + nodeId)) {

                                if(previousNode) {
                                    if(await this.db.has('node-pair:' + nodeId + '-' + previousNode)) {
                                        var edges = JSON.parse(await this.db.get('node-pair:' + nodeId + '-' + previousNode));
                                        for(var edge of edges) {
                                            
                                            if(!visitedEdges.has(edge))
                                                visitedEdgeList.push(edge);

                                            visitedEdges.add(edge);
                                        }
                                    }
                                }
                                previousNode = nodeId;
                            }
                        }     
                    }
                }

                var pathCandidate = new PathCandidate();
                pathCandidate.matchType = MatchType.HMM;
                pathCandidate.confidence = match.confidence;
                pathCandidate.originalFeature = feature;
                pathCandidate.segments = [];

                var segmentGeoms:turfHelpers.Feature<turfHelpers.MultiLineString> = turfHelpers.multiLineString([]);
                for(var edgeReferenceId of visitedEdgeList) {
                    var edgeRef = <SharedStreetsReference>this.tileIndex.objectIndex.get(edgeReferenceId);
                    var edgeGeom = <SharedStreetsGeometry>this.tileIndex.objectIndex.get(edgeRef.geometryId);

                    var pathSegment:PathSegment = new PathSegment();
                    pathSegment.geometryId = edgeGeom.id;
                    pathSegment.referenceId = edgeReferenceId;
                    // TODO calc directionality from graph edge trajectory possible...
                    pathCandidate.segments.push(pathSegment);

                    var segementGeom = <turfHelpers.Feature<turfHelpers.LineString>>this.tileIndex.featureIndex.get(edgeGeom.id);
                    segmentGeoms.geometry.coordinates.push(segementGeom.geometry.coordinates)
                }
                if(pathCandidate.segments.length > 0)
                    pathCandidate.matchedPath = segmentGeoms;

                return pathCandidate;

            }
            catch(e) {
                return null;
            }

 
    }


    async matchGeom(feature:turfHelpers.Feature<turfHelpers.LineString>) {
                    
        var pathCandidates:PathCandidate[] = [];
        
        // fall back to hmm for probabilistic path discovery
        if(!this.osrm)
            throw "Graph not buit. call buildGraph() before running queries."
        
        
        var hmmOptions = {
            coordinates: feature.geometry.coordinates,
            annotations: true,
            geometries: 'geojson',
            radiuses: Array(feature.geometry.coordinates.length).fill(this.searchRadius)
        };

        try {
            var matches = await new Promise((resolve, reject) => {
                this.osrm.match(hmmOptions, function(err, response) {
                    if (err) 
                        reject(err);
                    else
                        resolve(response)
                });
            });

            var visitedEdges:Set<string> = new Set();
            var visitedEdgeList:string[] = [];
            
            if(matches['matchings'] &&  matches['matchings'].length > 0) {
                
                var match = matches['matchings'][0];
                if(0 < match.confidence ) {

                    // this is kind of convoluted due to the sparse info returned in the OSRM annotations...
                    // write out sequence of nodes and edges as emitted from walking OSRM-returned nodes
                    // finding the actual posistion and directionality of the OSRM-edge within the ShSt graph 
                    // edge means that we have to snap start/end points in the OSRM geom
                    
                    //console.log(JSON.stringify(match.geometry));

                    var edgeCandidates;
                    var nodes:number[] = [];
                    var visitedNodes:Set<number> = new Set();
                    // ooof this is brutual -- need to unpack legs and reduce list... 
                    for(var leg of match['legs']) {
                        //console.log(leg['annotation']['nodes'])
                        for(var n of leg['annotation']['nodes']){ 
                            if(!visitedNodes.has(n) || nodes.length == 0)
                                nodes.push(n);

                            visitedNodes.add(n);
                        }
                    }

                // then group node pairs into unique edges...
                    var previousNode = null;
                    for(var nodeId of nodes) {
                        if(await this.db.has('node:' + nodeId)) {

                            if(previousNode) {
                                if(await this.db.has('node-pair:' + nodeId + '-' + previousNode)) {
                                    var edges = JSON.parse(await this.db.get('node-pair:' + nodeId + '-' + previousNode));
                                    for(var edge of edges) {
                                        
                                        if(!visitedEdges.has(edge))
                                            visitedEdgeList.push(edge);

                                        visitedEdges.add(edge);
                                    }
                                }
                            }
                            previousNode = nodeId;
                        }
                    }     
                }
            }
    
            if(visitedEdgeList.length > 0) {
                var startPoint = turfHelpers.point(feature.geometry.coordinates[0]);
                var endPoint = turfHelpers.point(feature.geometry.coordinates[feature.geometry.coordinates.length - 1]);


                var startCandidate:PointCandidate = await this.getPointCandidateFromRefId(startPoint, visitedEdgeList[0], null);
                var endCandidate:PointCandidate = await this.getPointCandidateFromRefId(endPoint, visitedEdgeList[visitedEdgeList.length - 1], null);

                var alreadyIncludedPaths:Set<string> = new Set();

                var pathCandidate = new PathCandidate();
                var matchWorked:boolean = true;

                pathCandidate.matchType = MatchType.HMM;
                pathCandidate.score = match.confidence;
                pathCandidate.originalFeature = feature;
                pathCandidate.matchedPath = turfHelpers.feature(match.geometry);

                //console.log(JSON.stringify(pathCandidate.matchedPath));

                pathCandidate.segments = [];

                var length = pathCandidate.getOriginalFeatureLength();

                for(var k = 0; k < visitedEdgeList.length; k++) {
                
                    var pathSegment:PathSegment = new PathSegment();
                    pathSegment.referenceId = visitedEdgeList[k];
                    var shstRef = <SharedStreetsReference>this.tileIndex.objectIndex.get(visitedEdgeList[k]);
                    pathSegment.referenceId = visitedEdgeList[k];
                    pathSegment.geometryId = shstRef.geometryId; 
                    pathCandidate.segments.push(pathSegment);
                    pathCandidate.segments[k].referenceLength = getReferenceLength(shstRef);
                }

                if(pathCandidate.segments.length > 0) {
                    pathCandidate.startPoint = startCandidate;
                
                    // build directionality into edge sequences   
                    for(var k = 0; k < pathCandidate.segments.length; k++) {
                        var edgeGeom = <SharedStreetsGeometry>this.tileIndex.objectIndex.get(pathCandidate.segments[k].geometryId);
                        
                        pathCandidate.segments[k].roadClass = roadClassConverter(edgeGeom.roadClass);
                        // if start and end are on the same graph edge make sure they're the same referenceId/direction
                        if(startCandidate.referenceId == endCandidate.referenceId) {
                            pathCandidate.endPoint = endCandidate;
                            pathCandidate.segments[k].section = [startCandidate.location, endCandidate.location];
                        }
                        else {

                            if(k == pathCandidate.segments.length - 1) {
                                pathCandidate.endPoint = endCandidate;
                                pathCandidate.segments[k].section = [0, endCandidate.location];
                            }
                            else if(k == 0) {
                                pathCandidate.segments[k].section = [pathCandidate.startPoint.location, pathCandidate.segments[k].referenceLength];
                            }
                            else {
                                pathCandidate.segments[k].section = [0, pathCandidate.segments[k].referenceLength];
                            }
                        } 
                        // put to/from on semgnet

                        if(edgeGeom.forwardReferenceId == pathCandidate.segments[k].referenceId) {
                            pathCandidate.segments[k].fromIntersectionId = edgeGeom.fromIntersectionId;
                            pathCandidate.segments[k].toIntersectionId = edgeGeom.toIntersectionId;
                        }
                        else {
                            // reverse to/from for back references
                            pathCandidate.segments[k].fromIntersectionId = edgeGeom.toIntersectionId;
                            pathCandidate.segments[k].toIntersectionId = edgeGeom.fromIntersectionId;
                        }                              
                    }

                    if(pathCandidate.startPoint.sideOfStreet == pathCandidate.endPoint.sideOfStreet)
                        pathCandidate.sideOfStreet = pathCandidate.startPoint.sideOfStreet;
                    else    
                        pathCandidate.sideOfStreet = ReferenceSideOfStreet.UNKNOWN;

                    var startDist = distance(startPoint, startCandidate.pointOnLine, {"units":"meters"});
                    var endDist = distance(endPoint, endCandidate.pointOnLine, {"units":"meters"});
                    pathCandidate.score = Math.round((rmse([startDist, endDist, pathCandidate.getLengthDelta()]) * 100)) / 100;
                    pathCandidates.push(pathCandidate);
                    // var refIdHash = uuidHash(pathCandidate.segments.map((value):string => {return value.referenceId; }).join(' '));

                    // if(matchWorked && !alreadyIncludedPaths.has(refIdHash)) {
                    //     alreadyIncludedPaths.add(refIdHash);
                    //     bestPathCandidate = pathCandidate;
                    // }   
                }    
            }
        }
        catch(e) {
            // no-op failed to match
        }
        
        if(pathCandidates.length > 0) {
            var bestPathCandidate = pathCandidates[0];
            var cleanedPath = [];
            var segCoords = [];

            var totalPathLength = 0;
            for(var i = 0; i < bestPathCandidate.segments.length; i++) {
                totalPathLength += bestPathCandidate.segments[i].section[1] - bestPathCandidate.segments[i].section[0]; 
            }
                
            for(var i = 0; i < bestPathCandidate.segments.length; i++) {
                var segment = bestPathCandidate.segments[i];
                
                // adding fudge factor for decimal precision issues
                if(segment.section[0] < segment.section[1] + this.searchRadius &&  segment.section[1] <= segment.referenceLength + this.searchRadius &&  segment.section[0] + this.searchRadius >= 0) {
                    
                    if(this.snapIntersections && (totalPathLength > this.searchRadius)) {
                        
                        if(i == 0 && segment.referenceLength - segment.section[0] < this.searchRadius)
                            continue;
                        
                        if(i == 0 && segment.section[0] < this.searchRadius)
                            segment.section[0] = 0;

                        if(i == bestPathCandidate.segments.length -1 && segment.section[1] < this.searchRadius)
                            continue;

                        if(i == bestPathCandidate.segments.length -1 && segment.referenceLength - segment.section[1] < this.searchRadius)
                            segment.section[1] = segment.referenceLength;

                        if( i > 0 && i < bestPathCandidate.segments.length -1) {
                            segment.section[0] = 0;
                            segment.section[1] = segment.referenceLength;
                        }
                    }

                    if(segment.section[0] == segment.section[1]) 
                        continue;

                    segment.geometry = await this.tileIndex.geom(segment.referenceId, segment.section[0],  segment.section[1]);   
                    if(segment.geometry) {
                        cleanedPath.push(segment);
                        segCoords.push(segment.geometry.geometry.coordinates)
                    }
                }
            }

            bestPathCandidate.segments = cleanedPath;
            
            if(cleanedPath.length == 0)
                return null;

            if(segCoords.length > 0) {
                var segmentGeoms:turfHelpers.Feature<turfHelpers.MultiLineString> = turfHelpers.multiLineString([]);
                segmentGeoms.geometry.coordinates = [...segCoords];
                bestPathCandidate.matchedPath = segmentGeoms;
            }   
        }
        return bestPathCandidate;
    }

    
	directionForRefId(refId:string):ReferenceDirection {

		var ref = <SharedStreetsReference>this.tileIndex.objectIndex.get(refId);

		if(ref) {
			var geom:SharedStreetsGeometry = <SharedStreetsGeometry>this.tileIndex.objectIndex.get(ref['geometryId']);

			if(geom) {
				if(geom['forwardReferenceId'] === ref['id'])
					return ReferenceDirection.FORWARD
				else if(geom['backReferenceId'] === ref['id'])
					return ReferenceDirection.BACKWARD
			}
		}
		return null;
	}

	toIntersectionIdForRefId(refId:string):string {
		var ref:SharedStreetsReference = <SharedStreetsReference>this.tileIndex.objectIndex.get(refId);
		return ref.locationReferences[ref.locationReferences.length - 1].intersectionId;								
	}

	fromIntersectionIdForRefId(refId:string):string {
		var ref:SharedStreetsReference = <SharedStreetsReference>this.tileIndex.objectIndex.get(refId);
		return ref.locationReferences[0].intersectionId;
	}

	async getPointCandidateFromRefId(searchPoint:turfHelpers.Feature<turfHelpers.Point>, refId:string, searchBearing:number):Promise<PointCandidate> {

		var reference = <SharedStreetsReference>this.tileIndex.objectIndex.get(refId);
		var geometry = <SharedStreetsGeometry>this.tileIndex.objectIndex.get(reference.geometryId);
		var geometryFeature = <turfHelpers.Feature<LineString>>this.tileIndex.featureIndex.get(reference.geometryId);

		var direction = ReferenceDirection.FORWARD;
		if(geometry.backReferenceId  && geometry.backReferenceId === refId)
			direction = ReferenceDirection.BACKWARD; 

		var pointOnLine = nearestPointOnLine(geometryFeature, searchPoint, {units:'meters'});	

		if(pointOnLine.properties.dist < this.searchRadius) {
			
			var refLength = 0;
			for(var lr of reference.locationReferences) {
				if(lr.distanceToNextRef)
					refLength = refLength + (lr.distanceToNextRef / 100);
			}
	
			var interceptBearing = normalizeAngle(bearing(pointOnLine, searchPoint));

			var i = pointOnLine.properties.index;

			if(geometryFeature.geometry.coordinates.length <= i + 1)
				i = i - 1;

			var lineBearing = bearing(geometryFeature.geometry.coordinates[i], geometryFeature.geometry.coordinates[i + 1]);

			if(direction === ReferenceDirection.BACKWARD)
				lineBearing += 180;

			lineBearing = normalizeAngle(lineBearing);	
			
			var pointCandidate:PointCandidate = new PointCandidate();

			pointCandidate.searchPoint = searchPoint;
			pointCandidate.pointOnLine = pointOnLine;


			pointCandidate.geometryId = geometryFeature.properties.id; 
			pointCandidate.referenceId = reference.id;
			pointCandidate.roadClass = roadClassConverter(geometry.roadClass);

			// if(this.includeStreetnames) {
			// 	var metadata = await this.cache.metadataById(pointCandidate.geometryId);
			// 	pointCandidate.streetname = metadata.name;
			// }

			pointCandidate.direction = direction;
			pointCandidate.referenceLength = refLength;

			if(direction === ReferenceDirection.FORWARD) 
				pointCandidate.location = pointOnLine.properties.location;
			else
				pointCandidate.location = refLength - pointOnLine.properties.location;

			pointCandidate.bearing = normalizeAngle(lineBearing);
			pointCandidate.interceptAngle = normalizeAngle(interceptBearing - lineBearing);

			pointCandidate.sideOfStreet = ReferenceSideOfStreet.UNKNOWN;
			if(pointCandidate.interceptAngle < 180) {
				pointCandidate.sideOfStreet = ReferenceSideOfStreet.RIGHT;
			}
			if(pointCandidate.interceptAngle > 180) {
				pointCandidate.sideOfStreet = ReferenceSideOfStreet.LEFT;
			}

			if(geometry.backReferenceId)
				pointCandidate.oneway = false;
			else
				pointCandidate.oneway = true;
			
			// check bearing and add to candidate list
			if(!searchBearing || angleDelta(searchBearing, lineBearing) < this.bearingTolerance)
				return pointCandidate;
		}

		return null;
	}

	getPointCandidateFromGeom(searchPoint:turfHelpers.Feature<turfHelpers.Point>, pointOnLine:turfHelpers.Feature<turfHelpers.Point>, candidateGeom:SharedStreetsGeometry, candidateGeomFeature:turfHelpers.Feature<LineString>,  searchBearing:number, direction:ReferenceDirection):PointCandidate {

		if(pointOnLine.properties.dist < this.searchRadius) {

			var reference:SharedStreetsReference;

			if(direction === ReferenceDirection.FORWARD) {
				reference = <SharedStreetsReference>this.tileIndex.objectIndex.get(candidateGeom.forwardReferenceId);
			}
			else {

				if(candidateGeom.backReferenceId) 
					reference = <SharedStreetsReference>this.tileIndex.objectIndex.get(candidateGeom.backReferenceId);
				else
					return null; // no back-reference

			}
				
			var refLength = 0;
			for(var lr of reference.locationReferences) {
				if(lr.distanceToNextRef)
					refLength = refLength + (lr.distanceToNextRef / 100);
			}

			var interceptBearing = normalizeAngle(bearing(pointOnLine, searchPoint));

			var i = pointOnLine.properties.index;

			if(candidateGeomFeature.geometry.coordinates.length <= i + 1)
				i = i - 1;

			var lineBearing = bearing(candidateGeomFeature.geometry.coordinates[i], candidateGeomFeature.geometry.coordinates[i + 1]);

			if(direction === ReferenceDirection.BACKWARD)
				lineBearing += 180;

			lineBearing = normalizeAngle(lineBearing);	
			
			var pointCandidate:PointCandidate = new PointCandidate();

			pointCandidate.searchPoint = searchPoint;
			pointCandidate.pointOnLine = pointOnLine;


			pointCandidate.geometryId = candidateGeomFeature.properties.id; 
			pointCandidate.referenceId = reference.id;
			pointCandidate.roadClass = roadClassConverter(candidateGeom.roadClass);

			// if(this.includeStreetnames) {
			// 	var metadata = await this.cache.metadataById(pointCandidate.geometryId);
			// 	pointCandidate.streetname = metadata.name;
			// }

			pointCandidate.direction = direction;
			pointCandidate.referenceLength = refLength;

			if(direction === ReferenceDirection.FORWARD) 
				pointCandidate.location = pointOnLine.properties.location;
			else
				pointCandidate.location = refLength - pointOnLine.properties.location;

			pointCandidate.bearing = normalizeAngle(lineBearing);
			pointCandidate.interceptAngle = normalizeAngle(interceptBearing - lineBearing);

			pointCandidate.sideOfStreet = ReferenceSideOfStreet.UNKNOWN;
			if(pointCandidate.interceptAngle < 180) {
				pointCandidate.sideOfStreet = ReferenceSideOfStreet.RIGHT;
			}
			if(pointCandidate.interceptAngle > 180) {
				pointCandidate.sideOfStreet = ReferenceSideOfStreet.LEFT;
			}

			if(candidateGeom.backReferenceId)
				pointCandidate.oneway = false;
			else
				pointCandidate.oneway = true;
			
			// check bearing and add to candidate list
			if(!searchBearing || angleDelta(searchBearing, lineBearing) < this.bearingTolerance)
				return pointCandidate;
		}

		return null;
	}

	async matchPoint(searchPoint:turfHelpers.Feature<turfHelpers.Point>, searchBearing:number, maxCandidates:number):Promise<PointCandidate[]> {
		this.tileIndex.addTileType(TileType.REFERENCE);
		var candidateFeatures = await this.tileIndex.nearby(searchPoint, TileType.GEOMETRY, this.searchRadius, this.tileParams);

		var candidates:PointCandidate[] = new Array();

		if(candidateFeatures && candidateFeatures.features) {
			for(var candidateFeature of candidateFeatures.features) {
				var candidateGeom:SharedStreetsGeometry = <SharedStreetsGeometry>this.tileIndex.objectIndex.get(candidateFeature.properties.id);
				var candidateGeomFeature:turfHelpers.Feature<turfHelpers.LineString> = <turfHelpers.Feature<turfHelpers.LineString>>this.tileIndex.featureIndex.get(candidateFeature.properties.id);
				var pointOnLine = nearestPointOnLine(candidateGeomFeature, searchPoint, {units:'meters'});	
				
				var forwardCandidate = await this.getPointCandidateFromGeom(searchPoint, pointOnLine, candidateGeom, candidateGeomFeature, searchBearing, ReferenceDirection.FORWARD);
				var backwardCandidate = await this.getPointCandidateFromGeom(searchPoint, pointOnLine, candidateGeom, candidateGeomFeature, searchBearing, ReferenceDirection.BACKWARD);
				
				if(forwardCandidate != null) {
					var snapped = false; 
					if(this.snapIntersections) {

						if(forwardCandidate.location < this.searchRadius) {

							var snappedForwardCandidate1 = Object.assign(new PointCandidate, forwardCandidate);
							snappedForwardCandidate1.location = 0;

							snappedForwardCandidate1.snappedPoint = along(candidateGeomFeature, 0, {"units":"meters"});

							candidates.push(snappedForwardCandidate1);
							snapped = true;

						}
						
						if(forwardCandidate.referenceLength - forwardCandidate.location < this.searchRadius) {
							var snappedForwardCandidate2 = Object.assign(new PointCandidate, forwardCandidate);
							snappedForwardCandidate2.location = snappedForwardCandidate2.referenceLength;

							snappedForwardCandidate2.snappedPoint = along(candidateGeomFeature, snappedForwardCandidate2.referenceLength, {"units":"meters"});

							candidates.push(snappedForwardCandidate2);
							snapped = true;
						}

					}

					if(!snapped)  {
						candidates.push(forwardCandidate);
					}
				}

				if(backwardCandidate != null) {

					var snapped = false; 

					if(this.snapIntersections) {

						if(backwardCandidate.location < this.searchRadius) {
							var snappedBackwardCandidate1:PointCandidate = Object.assign(new PointCandidate, backwardCandidate);
							snappedBackwardCandidate1.location = 0;

							// not reversing the geom so snap to end on backRefs
							snappedBackwardCandidate1.snappedPoint = along(candidateGeomFeature, snappedBackwardCandidate1.referenceLength, {"units":"meters"});

							candidates.push(snappedBackwardCandidate1);
							snapped = true;
						}
						
						if(backwardCandidate.referenceLength - backwardCandidate.location < this.searchRadius) {
							var snappedBackwardCandidate2 = Object.assign(new PointCandidate, backwardCandidate);
							snappedBackwardCandidate2.location = snappedBackwardCandidate2.referenceLength;

							// not reversing the geom so snap to start on backRefs
							snappedBackwardCandidate2.snappedPoint = along(candidateGeomFeature, 0, {"units":"meters"});

							candidates.push(snappedBackwardCandidate2);
							snapped = true;
						}
					}

					if(!snapped)  {
						candidates.push(backwardCandidate);
					}
				}
			}
		}

		var sortedCandidates = candidates.sort((p1, p2) => {
			p1.calcScore();
			p2.calcScore();
			if(p1.score > p2.score) {
				return 1;
			}
			if(p1.score < p2.score) {
				return -1;
			}
			return 0;
		});
		
		if(sortedCandidates.length > maxCandidates) {
			sortedCandidates = sortedCandidates.slice(0, maxCandidates);
		}
	
		return sortedCandidates;
	}
}