Initial release

src/position.ts

@@ -0,0 +1,72 @@
+import { IPosition, ISymbol } from "./frame.types";
+
+export class Symbol implements ISymbol {
+  table: string;    // Symbol table identifier
+  code: string;     // Symbol code
+
+  constructor(table: string, code?: string) {
+    if (code === undefined) {
+      if (table.length === 2) {
+        this.code = table[1];
+        this.table = table[0];
+      } else {
+        throw new Error(`Invalid symbol format: '${table}' (expected 2 characters if code is not provided)`);
+      }
+    } else {
+      this.table = table;
+      this.code = code;
+    }
+  }
+
+  public toString(): string {
+    return `${this.table}${this.code}`;
+  }
+}
+
+export class Position implements IPosition {
+  latitude: number;   // Decimal degrees
+  longitude: number;  // Decimal degrees
+  ambiguity?: number; // Position ambiguity (0-4)
+  altitude?: number;  // Meters
+  speed?: number;     // Speed in knots/kmh depending on source
+  course?: number;    // Course in degrees
+  symbol?: Symbol;
+  comment?: string;
+
+  constructor(data: Partial<IPosition>) {
+    this.latitude = data.latitude ?? 0;
+    this.longitude = data.longitude ?? 0;
+    this.ambiguity = data.ambiguity;
+    this.altitude = data.altitude;
+    this.speed = data.speed;
+    this.course = data.course;
+    if (typeof data.symbol === 'string') {
+      this.symbol = new Symbol(data.symbol);
+    } else if (data.symbol) {
+      this.symbol = new Symbol(data.symbol.table, data.symbol.code);
+    }
+    this.comment = data.comment;
+  }
+
+  public toString(): string {
+    const latStr = this.latitude.toFixed(5);
+    const lonStr = this.longitude.toFixed(5);
+    const altStr = this.altitude !== undefined ? `,${this.altitude}m` : '';
+    return `${latStr},${lonStr}${altStr}`;
+  }
+
+  public distanceTo(other: IPosition): number {
+    const R = 6371e3; // Earth radius in meters
+    const φ1 = this.latitude * Math.PI / 180;
+    const φ2 = other.latitude * Math.PI / 180;
+    const Δφ = (other.latitude - this.latitude) * Math.PI / 180;
+    const Δλ = (other.longitude - this.longitude) * Math.PI / 180;
+
+    const a = Math.sin(Δφ/2) * Math.sin(Δφ/2) +
+              Math.cos(φ1) * Math.cos(φ2) *
+              Math.sin(Δλ/2) * Math.sin(Δλ/2);
+    const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
+
+    return R * c; // Distance in meters
+  }
+}