feat: added Octopus CLI version fetcher

src/octopusCLIVersionFetcher.ts

@@ -0,0 +1,89 @@
+import {maxSatisfying, valid} from 'semver'
+
+export class OctopusCLIVersionFetcher {
+  constructor(readonly versions: string[]) {}
+
+  getVersion(versionSpec: string): string | null {
+    if (versionSpec === '*') {
+      return maxSatisfying(this.versions, versionSpec)
+    }
+
+    if (valid(versionSpec) === null) {
+      const parts = versionSpec.split('.')
+      if (parts.length > 3) {
+        throw new Error(
+          `The '${versionSpec}' is an invalid version, a version needs to be a maximum of three parts.`
+        )
+      }
+
+      if (parts.length === 1) {
+        const majorVersion = parts[0]
+        if (Number.isNaN(Number.parseInt(majorVersion))) {
+          throw new Error(
+            `The '${versionSpec}' version needs to specify a number or '*' for its major part.`
+          )
+        }
+      }
+
+      if (parts.length === 2) {
+        const majorVersion = parts[0]
+        const minorVersion = parts[1]
+
+        // the major version number must be a number
+        if (Number.isNaN(Number.parseInt(majorVersion))) {
+          throw new Error(
+            `The '${versionSpec}' version needs to specify a number for its major part.`
+          )
+        }
+
+        if (
+          minorVersion !== '*' &&
+          Number.isNaN(Number.parseInt(minorVersion))
+        ) {
+          throw new Error(
+            `The '${versionSpec}' version needs to specify a number or '*' for its minor part.`
+          )
+        }
+      }
+
+      if (parts.length === 3) {
+        const majorVersion = parts[0]
+        const minorVersion = parts[1]
+        const patchVersion = parts[2]
+
+        // the major version number must be a number
+        if (Number.isNaN(Number.parseInt(majorVersion))) {
+          throw new Error(
+            `The '${versionSpec}' version needs to specify a number for its major part.`
+          )
+        }
+
+        // the minor version number must be a number
+        if (Number.isNaN(Number.parseInt(minorVersion))) {
+          throw new Error(
+            `The '${versionSpec}' version needs to specify a number for its minor part.`
+          )
+        }
+
+        if (
+          patchVersion !== '*' &&
+          Number.isNaN(Number.parseInt(patchVersion))
+        ) {
+          throw new Error(
+            `The '${versionSpec}' version needs to specify a number or '*' for its patch part.`
+          )
+        }
+      }
+    }
+
+    const version = maxSatisfying(this.versions, versionSpec)
+
+    if (!version) {
+      throw new Error(
+        `A version satisfying '${versionSpec}' could not be found.`
+      )
+    }
+
+    return version
+  }
+}