From c2f0d58b904c1ae94a9df1d93aef731ee1826725 Mon Sep 17 00:00:00 2001
From: Gal Schlezinger <gal@spitfire.co.il>
Date: Wed, 22 May 2019 20:01:50 +0300
Subject: [PATCH] Implement `realpath` instead of binding to C library (#102)

drop Filename.realpath usage, for crossplatform support
---
 executable/ListInstallations.re | 37 ----------------------------
 executable/ListLocal.re         |  4 +--
 executable/ListRemote.re        |  4 +--
 library/Fs.re                   | 25 +++++++++++++------
 library/Versions.re             | 43 +++++++++++++++------------------
 5 files changed, 42 insertions(+), 71 deletions(-)
 delete mode 100644 executable/ListInstallations.re

diff --git a/executable/ListInstallations.re b/executable/ListInstallations.re
deleted file mode 100644
index 98a1543..0000000
--- a/executable/ListInstallations.re
+++ /dev/null
@@ -1,37 +0,0 @@
-open Fnm;
-
-let colorizeVersions = (~current, ~versions) => {
-  let strings =
-    versions
-    |> List.map(version => {
-         open Versions.Local;
-         let str = "- " ++ version.name;
-
-         let color =
-           current
-           |> Opt.bind(current =>
-                current.name == version.name ? Some(Pastel.Green) : None
-              );
-
-         <Pastel ?color> str </Pastel>;
-       });
-
-  <Pastel>
-    <Pastel color=Pastel.Cyan> "## List of installed versions:\n" </Pastel>
-    <Pastel> ...strings </Pastel>
-  </Pastel>;
-};
-
-let getVersionsString = () =>
-  Result.(
-    {
-      let%bind versions =
-        Versions.getInstalledVersions() |> Result.map(Array.to_list);
-
-      let current = Versions.getCurrentVersion();
-
-      colorizeVersions(~current, ~versions) |> Result.return;
-    }
-  );
-
-let run = () => getVersionsString() |> Result.map(Console.log) |> Lwt.return;
diff --git a/executable/ListLocal.re b/executable/ListLocal.re
index ed875d4..3858454 100644
--- a/executable/ListLocal.re
+++ b/executable/ListLocal.re
@@ -8,8 +8,8 @@ let main = () =>
       let%lwt versions =
         try%lwt (Versions.getInstalledVersions()) {
         | _ => Lwt.fail(Cant_read_local_versions)
-        };
-      let currentVersion = Versions.getCurrentVersion();
+        }
+      and currentVersion = Versions.getCurrentVersion();
 
       Console.log("The following versions are installed:");
 
diff --git a/executable/ListRemote.re b/executable/ListRemote.re
index 0fdd11e..5ea8e0b 100644
--- a/executable/ListRemote.re
+++ b/executable/ListRemote.re
@@ -3,8 +3,8 @@ open Fnm;
 let run = () => {
   Console.log("Looking for some node versions upstream...");
 
-  let%lwt versions = Versions.getRemoteVersions();
-  let currentVersion = Versions.getCurrentVersion();
+  let%lwt versions = Versions.getRemoteVersions()
+  and currentVersion = Versions.getCurrentVersion();
 
   versions
   |> List.iter(version => {
diff --git a/library/Fs.re b/library/Fs.re
index 061c395..3843cb7 100644
--- a/library/Fs.re
+++ b/library/Fs.re
@@ -1,5 +1,3 @@
-open Core;
-
 let readdir = dir => {
   let items = ref([]);
   let%lwt dir = Lwt_unix.opendir(dir);
@@ -40,9 +38,22 @@ let exists = path => {
   };
 };
 
-let realpath = Filename.realpath;
+let readlink = path =>
+  try%lwt (Lwt_unix.readlink(path) |> Lwt.map(x => Ok(x))) {
+  | err => Lwt.return_error(err)
+  };
 
-let try_readlink = path =>
-  try (Ok(Unix.readlink(path))) {
-  | err => Error(err)
-  };
\ No newline at end of file
+type path =
+  | Exists(string)
+  | Missing(string);
+
+let rec realpath = path => {
+  switch%lwt (readlink(path)) {
+  | Ok(path) => realpath(path)
+  | Error(_) =>
+    switch%lwt (exists(path)) {
+    | true => Exists(path) |> Lwt.return
+    | false => Missing(path) |> Lwt.return
+    }
+  };
+};
diff --git a/library/Versions.re b/library/Versions.re
index 707fcdf..ed6888c 100644
--- a/library/Versions.re
+++ b/library/Versions.re
@@ -72,19 +72,23 @@ module Aliases = {
       | _ => Lwt.return([])
       };
     aliases
-    |> List.map(alias => {
+    |> Lwt_list.map_p(alias => {
          let fullPath = Filename.concat(Directories.aliases, alias);
-         {
+         let%lwt realpath =
+           Filename.concat(Directories.aliases, alias)
+           |> Fs.realpath
+           |> Lwt.map(
+                fun
+                | Fs.Exists(x) => x
+                | Fs.Missing(x) => x,
+              );
+
+         Lwt.return({
            name: alias,
            fullPath,
-           versionName:
-             Filename.concat(Directories.aliases, alias)
-             |> Fs.realpath
-             |> Filename.dirname
-             |> Filename.basename,
-         };
-       })
-    |> Lwt.return;
+           versionName: realpath |> Filename.dirname |> Filename.basename,
+         });
+       });
   };
 
   let byVersion = () => {
@@ -172,24 +176,17 @@ let endsWith = (~suffix, str) => {
 exception No_Download_For_System(System.NodeOS.t, System.NodeArch.t);
 
 let getCurrentVersion = () => {
-  switch (Fs.realpath(Directories.currentVersion)) {
-  | installationPath =>
+  switch%lwt (Fs.realpath(Directories.currentVersion)) {
+  | Missing(x) when x == Directories.currentVersion => Lwt.return_none
+  | Missing(_) => Lwt.return_some(Local.systemVersion)
+  | Exists(installationPath) =>
     let fullPath = Filename.dirname(installationPath);
-    Some(
+    Lwt.return_some(
       Local.{fullPath, name: Core.Filename.basename(fullPath), aliases: []},
     );
-  | exception (Unix.Unix_error(_, _, _)) =>
-    switch (Fs.try_readlink(Directories.currentVersion)) {
-    | Ok(x)
-        when
-          Core.String.substr_index(x, ~pattern=Local.systemVersion.fullPath)
-          == Some(0) =>
-      Some(Local.systemVersion)
-    | Ok(_)
-    | Error(_) => None
-    }
   };
 };
+
 let getInstalledVersions = () => {
   let%lwt versions =
     Fs.readdir(Directories.nodeVersions) |> Lwt.map(List.sort(compare))