split the common.ts into several files

src/core/versionManager.ts

@@ -0,0 +1,59 @@
+import cmp from "semver-compare";
+import * as semver from "semver";
+import { injectable, inject } from "inversify";
+
+import { IBuildAgent, TYPES } from "./common";
+
+export interface IVersionManager {
+    isExplicitVersion(versionSpec: string): boolean;
+    evaluateVersions(versions: string[], versionSpec: string): string;
+    cleanVersion(version: string): string;
+}
+
+@injectable()
+export class VersionManager implements IVersionManager {
+
+    private buildAgent: IBuildAgent;
+    constructor(
+        @inject(TYPES.IBuildAgent) buildAgent: IBuildAgent,
+    ) {
+        this.buildAgent = buildAgent;
+    }
+
+    public isExplicitVersion(versionSpec: string): boolean {
+        const c = semver.clean(versionSpec);
+        this.buildAgent.debug("isExplicit: " + c);
+
+        const valid = semver.valid(c) != null;
+        this.buildAgent.debug("explicit? " + valid);
+
+        return valid;
+    }
+
+    public evaluateVersions(versions: string[], versionSpec: string): string {
+        let version: string;
+        this.buildAgent.debug("evaluating " + versions.length + " versions");
+        versions = versions.sort(cmp);
+        for (let i = versions.length - 1; i >= 0; i--) {
+        const potential: string = versions[i];
+        const satisfied: boolean = semver.satisfies(potential, versionSpec);
+        if (satisfied) {
+            version = potential;
+            break;
+        }
+    }
+
+        if (version) {
+            this.buildAgent.debug("matched: " + version);
+    } else {
+        this.buildAgent.debug("match not found");
+    }
+
+        return version;
+    }
+
+    public cleanVersion(version: string): string {
+        this.buildAgent.debug("cleaning: " + version);
+        return semver.clean(version);
+    }
+}