Add support for interactive installation for use (#86)

executable/Use.re

@@ -69,17 +69,41 @@ let main = (~version as providedVersion, ~quiet) => {
   switchVersion(~version, ~quiet);
 };
 
-let run = (~version, ~quiet) =>
+let rec askIfInstall = (~version, ~quiet, retry) => {
+  let%lwt _ =
+    Lwt_io.write(
+      Lwt_io.stderr,
+      <Pastel color=Pastel.Red> "Do you want to install it? [y/n] " </Pastel>,
+    );
+  switch%lwt (Lwt_io.read_line(Lwt_io.stdin)) {
+  | "Y"
+  | "y" =>
+    let%lwt _ = Install.run(~version);
+    retry(~version, ~quiet);
+  | "N"
+  | "n" => Lwt_io.write_line(Lwt_io.stderr, "not installing!")
+  | _ =>
+    let%lwt _ =
+      Lwt_io.write_line(Lwt_io.stderr, "Invalid response. Please try again:");
+    askIfInstall(~version, ~quiet, retry);
+  };
+};
+
+let rec run = (~version, ~quiet) =>
   try%lwt (main(~version, ~quiet)) {
-  | Version_Not_Installed(version) =>
+  | Version_Not_Installed(versionString) =>
     log(
       ~quiet,
       <Pastel color=Pastel.Red>
         "The following version is not installed: "
-        version
+        versionString
       </Pastel>,
     );
-    exit(1);
+    if (Fnm.Config.FNM_INTERACTIVE_CLI.get()) {
+      askIfInstall(~version, ~quiet, run);
+    } else {
+      exit(1);
+    };
   | Dotfiles.Conflicting_Dotfiles_Found(v1, v2) =>
     log(
       ~quiet,

library/Config.re

@@ -16,7 +16,8 @@ module EnvVar =
          },
        ) => {
   include M;
-  let getOpt = () => Sys.getenv_opt(name) |> Opt.map(parse);
+  let optValue = Sys.getenv_opt(name) |> Opt.map(parse);
+  let getOpt = () => optValue;
   let get = () => Opt.(getOpt() or default);
   let docInfo = {name, doc, default: unparse(default)};
 };
@@ -62,4 +63,38 @@ module FNM_MULTISHELL_PATH =
     let default = "";
   });
 
-let getDocs = () => [FNM_DIR.docInfo, FNM_NODE_DIST_MIRROR.docInfo];
+let parseBooleanOrDie = (~name, str) =>
+  switch (bool_of_string_opt(str)) {
+  | Some(boolean) => boolean
+  | None =>
+    let errorString =
+      <Pastel color=Pastel.Red>
+        <Pastel color=Pastel.Cyan> str </Pastel>
+        " isn't a valid option for "
+        <Pastel color=Pastel.Magenta> name </Pastel>
+        " which assumes a boolean value. Consider passing "
+        <Pastel color=Pastel.Cyan> "true" </Pastel>
+        " or "
+        <Pastel color=Pastel.Cyan> "false" </Pastel>
+        "."
+      </Pastel>;
+    Printf.eprintf("%s\n", errorString);
+    exit(1);
+  };
+
+module FNM_INTERACTIVE_CLI =
+  EnvVar({
+    type t = bool;
+    let default = Unix.(isatty(stdin) && isatty(stdout) && isatty(stderr));
+    let unparse = string_of_bool;
+    let name = "FNM_INTERACTIVE_CLI";
+    let doc = "Should the CLI be interactive? true/false";
+    let parse = parseBooleanOrDie(~name);
+  });
+
+let getDocs = () => [
+  FNM_DIR.docInfo,
+  FNM_NODE_DIST_MIRROR.docInfo,
+  FNM_MULTISHELL_PATH.docInfo,
+  FNM_INTERACTIVE_CLI.docInfo,
+];

library/dune

@@ -7,6 +7,6 @@
    (name Fnm)
    ; Other libraries list this name in their package.json 'require' field to use this library.
    (public_name fnm.lib)
-   (libraries  str core lwt ssl lwt_ssl lambdasoup semver cohttp cohttp-lwt cohttp-lwt-unix )
+   (libraries  pastel.lib str core lwt ssl lwt_ssl lambdasoup semver cohttp cohttp-lwt cohttp-lwt-unix )
    (preprocess ( pps lwt_ppx ppx_let ))  ; From package.json preprocess field
 )

package.json

@@ -31,6 +31,7 @@
         "ppx_let"
       ],
       "require": [
+        "pastel.lib",
         "str",
         "core",
         "lwt",