Implement fallback install and outputs (#2)

* Add better version support. Restructure code. Implement OS agnostic fallback

* Support latest for cabal and stack. Add enable-stack option.

* Add outputs

* Update documentation. Change default for GHC to latest.

src/setup-haskell.ts

@@ -1,38 +1,37 @@
 import * as core from '@actions/core';
-import {getOpts, getDefaults} from './installer';
+import {getOpts, getDefaults, Tool} from './opts';
+import {installTool} from './installer';
+import type {OS} from './opts';
 import {exec} from '@actions/exec';
 
 (async () => {
   try {
-    const opts = getOpts(getDefaults());
     core.info('Preparing to setup a Haskell environment');
-    core.debug(`Options are: ${JSON.stringify(opts)}`);
+    const opts = getOpts(getDefaults());
 
-    for (const [tool, o] of Object.entries(opts)) {
-      if (o.enable) {
-        core.info(`Installing ${tool} version ${o.version}`);
-        await o.install(o.version);
-      }
-    }
+    for (const [t, {resolved}] of Object.entries(opts).filter(o => o[1].enable))
+      await core.group(`Installing ${t} version ${resolved}`, async () =>
+        installTool(t as Tool, resolved, process.platform as OS)
+      );
 
-    if (opts.stack.setup) {
-      core.startGroup('Pre-installing GHC with stack');
-      await exec('stack', ['setup', opts.ghc.version]);
-      core.endGroup();
-    }
+    if (opts.stack.setup)
+      await core.group('Pre-installing GHC with stack', async () =>
+        exec('stack', ['setup', opts.ghc.resolved])
+      );
 
-    if (opts.cabal.enable) {
-      core.startGroup('Setting up cabal');
-      await exec('cabal', [
-        'user-config',
-        'update',
-        '-a',
-        'http-transport: plain-http',
-        '-v3'
-      ]);
-      await exec('cabal', ['update']);
-      core.endGroup();
-    }
+    if (opts.cabal.enable)
+      await core.group('Setting up cabal', async () => {
+        await exec(
+          'cabal user-config update -a "http-transport: plain-http" -v3'
+        );
+        await exec('cabal', ['update']);
+        if (process.platform === 'win32') {
+          await exec('cabal user-config update -a "store-dir: C:\\sr" -v3');
+          core.setOutput('cabal-store', 'C:\\sr');
+        } else {
+          core.setOutput('cabal-store', `${process.env.HOME}/.cabal/store`);
+        }
+      });
   } catch (error) {
     core.setFailed(error.message);
   }