initial commit and working code

.gitignore

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+node_modules/

app.js

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+// Reaktor Orbital Challenge
+// (c) Jonne Pihlanen 2016
+
+const
+    fsp = require('fs-promise'),
+    csv = require('csv');
+
+fsp.readFile('./data2.csv')
+    .then((contents) => {
+        csv.parse(contents, (err, data) => {
+
+            let seed = data.shift()[0];
+            console.log(seed);
+            let route = data.pop();
+            let start = {
+                latitude: parseFloat(route[1]),
+                longitude: parseFloat(route[2]),
+                altitude: 0
+            };
+
+            let end = {
+                latitude: parseFloat(route[3]),
+                longitude: parseFloat(route[4]),
+                altitude: 0
+            };
+
+            data = data.map((item) => {
+                return {
+                    id: item[0],
+                    latitude: parseFloat(item[1]),
+                    longitude: parseFloat(item[2]),
+                    altitude: parseFloat(item[3])
+                };
+            });
+
+            let horizonA = distanceToHorizon(start);
+            let startPointSatellites = [];
+            data.forEach((item) => {
+                let distance = calculateDistance(calculateCoordinate(start), calculateCoordinate(item));
+                let horizonB = distanceToHorizon(item);
+                if (distance <= horizonA + horizonB) {
+                    // console.log("start position can see satellite " + item.id);
+                    startPointSatellites.push(item);
+                }
+            });
+
+            horizonA = distanceToHorizon(end);
+            let endPointSatellites = [];
+            data.forEach((item) => {
+                distance = calculateDistance(calculateCoordinate(end), calculateCoordinate(item));
+                horizonB = distanceToHorizon(item);
+                if (distance <= horizonA + horizonB) {
+                    // console.log("end position can see satellite " + item.id);
+                    endPointSatellites.push(item);
+                }
+            });
+
+            startPointSatellites.forEach((item) => {
+                console.log("finding routes for " + item.id);
+                findRoute(item, endPointSatellites, data, [], [item]);
+            });
+
+        });
+    });
+
+// algorithm to find the route
+const findRoute = (itemA, endPointSatellites, allSatellites, nextSatellites, route) => {
+
+    // console.log("processing satellite " + itemA.id);
+    if(endPointSatellites.indexOf(itemA) > -1) {
+        console.log(route.map(item => item.id).toString());
+        return route.push(itemA);
+    }
+
+    let horizonA = distanceToHorizon(itemA);
+    allSatellites.forEach((itemB) => {
+        let distance = calculateDistance(calculateCoordinate(itemA), calculateCoordinate(itemB));
+        let horizonB = distanceToHorizon(itemB);
+        if (distance <= horizonA + horizonB && itemA.id != itemB.id && route.indexOf(itemB) === -1) {
+            // console.log("satellite " + itemA.id + " can see satellite " + itemB.id);
+            route.push(itemB);
+            return findRoute(itemB, endPointSatellites, allSatellites, [], route);
+        }
+    });
+}
+
+// the earth was considered to be a round sphere
+// http://stackoverflow.com/questions/8981943/lat-long-to-x-y-z-position-in-js-not-working
+const calculateCoordinate = (item) => {
+    let cosLat = Math.cos(item.latitude * Math.PI / 180.0);
+    let sinLat = Math.sin(item.latitude * Math.PI / 180.0);
+    let cosLon = Math.cos(item.longitude * Math.PI / 180.0);
+    let sinLon = Math.sin(item.longitude * Math.PI / 180.0);
+    let rad = 6371000;
+    return {
+        x: rad * cosLat * cosLon,
+        y: rad * cosLat * sinLon,
+        z: rad * sinLat
+    };
+}
+
+// distance between two XYZ points
+const calculateDistance = (itemA, itemB) => {
+    return Math.sqrt((itemB.x - itemA.x)*(itemB.x - itemA.x) + (itemB.y - itemA.y)*(itemB.y - itemA.y) + (itemB.z - itemA.z)*(itemB.z - itemA.z));
+}
+
+// https://en.wikipedia.org/wiki/Horizon#Exact_formula_for_a_spherical_Earth
+const distanceToHorizon = (item) => {
+    let rad = 6378.137;
+    return Math.sqrt((2*rad*item.altitude) + item.altitude*item.altitude) * 1000;
+}

data1.csv

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+#SEED: 0.7474189903587103,,,,
+SAT0,-49.989809896445685,-141.67445792329482,443.3808469970726,
+SAT1,-39.10675429294448,-74.544837218822,499.0880898277302,
+SAT2,83.42233682389036,-77.11484255197678,413.6241955027923,
+SAT3,-10.13892273327032,90.16479571928511,398.23254533024016,
+SAT4,29.404880122097865,8.144846168937875,489.3606360928758,
+SAT5,-81.82109567686196,133.68988873756825,544.3103553976588,
+SAT6,-46.24260757795606,-14.847486394058478,470.76451990187206,
+SAT7,64.42485618393547,47.37887014040777,610.364816764163,
+SAT8,19.08126826842792,-24.910706666102328,397.8221275369171,
+SAT9,19.566075415533916,-31.470111487830707,635.7562439676083,
+SAT10,85.01941071114706,173.7908087477121,402.78065912402116,
+SAT11,71.14558716997774,70.72320103888183,533.5347325592111,
+SAT12,52.458628054529186,-47.22552102041729,641.7820502721927,
+SAT13,-23.857902803843032,-40.95816667324394,473.15051553037347,
+SAT14,-12.122575869688262,114.90112609581126,697.559575298595,
+SAT15,45.46488891960638,-8.87289292209013,569.0871840142252,
+SAT16,-47.86318138083877,59.64941635409426,657.8632623519819,
+SAT17,-5.788814136343348,-56.662480811863404,629.4097191724984,
+SAT18,-89.31019373375635,-88.37195445788251,689.5225802781598,
+SAT19,74.39131000618991,-60.52409542667834,676.9580243561712,
+ROUTE,-39.94649332605746,58.69416308741867,38.379492171579216,-33.239929753094685

data2.csv

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+#SEED: 0.8512005945667624,,,,
+SAT0,-31.515514556212928,87.08179651062551,582.7358538139997,
+SAT1,-48.26934238839663,-122.93555366860264,469.0712192530458,
+SAT2,-27.667364301435164,-140.02507468426145,303.68912409756587,
+SAT3,-76.74930806305389,144.8698532145853,370.2907496229141,
+SAT4,12.909577915857,124.03325931953088,341.09392296390376,
+SAT5,51.89096871691069,-28.03031629250512,509.83831068491713,
+SAT6,-80.64053148785267,-102.01806140406197,448.66298545343295,
+SAT7,14.714737200122883,-136.53179390731265,506.2145001678505,
+SAT8,-3.1155689906874926,28.12854530814883,461.51102445647126,
+SAT9,-11.503365635971491,-142.85187591007136,367.1868219400208,
+SAT10,88.59075908732822,3.60109102177654,662.6825328832408,
+SAT11,15.62638727922976,-66.32963975873389,417.48130055228233,
+SAT12,53.46937817062371,16.147183636313855,351.63545201171496,
+SAT13,14.571497481218316,55.72448076814268,385.7667154484617,
+SAT14,-88.946474171508,-13.231664391900978,650.3857506397896,
+SAT15,79.1935663590344,124.95624067309564,452.80276549592895,
+SAT16,55.36611460583683,-156.18665935606288,648.9629233992027,
+SAT17,26.76916805093866,-95.65338067833284,549.1524083387458,
+SAT18,44.66441827137686,159.7256268024209,593.6384154112761,
+SAT19,-70.97513902215374,-118.07840212299234,491.0271587520272,
+ROUTE,-65.1386535041511,165.61800790075932,69.2357035498647,69.32549665359181

package.json

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+{
+  "name": "reaktor-orbital-challenge",
+  "version": "1.0.0",
+  "description": "",
+  "main": "app.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "Jonne Pihlanen",
+  "license": "ISC",
+  "dependencies": {
+    "csv": "^0.4.6",
+    "fs-promise": "^0.5.0"
+  }
+}