mimeo: fix infinite loop when dispatching non-specialized http/s URLs

hosts/common/programs/default.nix

@@ -44,7 +44,7 @@
     ./lemoa.nix
     ./mako.nix
     ./mepo.nix
-    ./mimeo.nix
+    ./mimeo
     ./mopidy.nix
     ./mpv.nix
     ./msmtp.nix

hosts/common/programs/firefox.nix

@@ -204,8 +204,6 @@ in
           "x-scheme-handler/about" = desktop;
           "x-scheme-handler/unknown" = desktop;
         };
-        # TODO: cleanup mimeo and remove this
-        mime.urlAssociations."^https?://.*" = "librewolf --name librewolf %U";
 
         # env.BROWSER = "${package}/bin/${cfg.browser.libName}";
         env.BROWSER = cfg.browser.libName;  # used by misc tools like xdg-email, as fallback

hosts/common/programs/mimeo.nix

@@ -1,42 +0,0 @@
-{ config, lib, pkgs, ... }:
-let
-  # [ ProgramConfig ]
-  enabledPrograms = builtins.filter
-    (p: p.enabled)
-    (builtins.attrValues config.sane.programs);
-
-  fmtAssoc = regex: cmd: ''
-    ${cmd}
-      ${regex}
-  '';
-  assocs = builtins.map
-    (program: lib.mapAttrsToList fmtAssoc program.mime.urlAssociations)
-    enabledPrograms;
-  assocs' = lib.flatten assocs;
-in
-{
-  sane.programs.mimeo = {
-    package = pkgs.mimeo.overridePythonAttrs (upstream: {
-      nativeBuildInputs = (upstream.nativeBuildInputs or []) ++ [
-        pkgs.copyDesktopItems
-      ];
-      desktopItems = [
-        (pkgs.makeDesktopItem {
-          name = "mimeo";
-          desktopName = "Mimeo";
-          exec = "mimeo %U";
-          comment = "Open files by MIME-type or file name using regular expressions.";
-        })
-      ];
-      installPhase = ''
-        runHook preInstall
-        ${upstream.installPhase}
-        runHook postInstall
-      '';
-    });
-    fs.".config/mimeo/associations.txt".symlink.text = lib.concatStringsSep "\n" assocs';
-    mime.priority = 20;
-    mime.associations."x-scheme-handler/http" = "mimeo.desktop";
-    mime.associations."x-scheme-handler/https" = "mimeo.desktop";
-  };
-}

hosts/common/programs/mimeo/default.nix

@@ -0,0 +1,78 @@
+# mimeo is an exec dispatcher like xdg-open, but why allows mapping different URL regexes to different handlers.
+# my setup sets mimeo as the default http/https handler,
+# and from there it dispatches specialized rules, falling back to the original http/https handler if no URL specialization exists
+{ config, lib, pkgs, ... }:
+let
+  mimeo-open-desktop = pkgs.static-nix-shell.mkPython3Bin {
+    pname = "mimeo-open-desktop";
+    src = ./.;
+    pkgs = [ "mimeo" ];
+  };
+
+  # [ProgramConfig]
+  enabledPrograms = builtins.filter
+    (p: p.enabled)
+    (builtins.attrValues config.sane.programs);
+
+  # [ProgramConfig]
+  sortedPrograms = builtins.sort
+    (l: r: l.priority or 1000 < r.priority or 1000)
+    enabledPrograms;
+
+  fmtAssoc = regex: desktop: ''
+    ${mimeo-open-desktop}/bin/mimeo-open-desktop ${desktop} %U
+      ${regex}
+  '';
+  assocs = builtins.map
+    (program: lib.mapAttrsToList fmtAssoc program.mime.urlAssociations)
+    sortedPrograms;
+  assocs' = lib.flatten assocs;
+
+  fmtFallbackAssoc = mimeType: desktop: if mimeType == "x-scheme-handler/http" then ''
+    ${mimeo-open-desktop}/bin/mimeo-open-desktop ${desktop} %U
+      ^http://.*
+  '' else if mimeType == "x-scheme-handler/https" then ''
+    ${mimeo-open-desktop}/bin/mimeo-open-desktop ${desktop} %U
+      ^https://.*
+  '' else "";
+  fmtFallbackAssoc' = mimeType: desktop:
+    lib.optionalString (desktop != "mimeo.desktop") (fmtFallbackAssoc mimeType desktop);
+
+  fallbackAssocs = builtins.map
+    (program: lib.mapAttrsToList fmtFallbackAssoc' program.mime.associations)
+    sortedPrograms;
+  fallbackAssocs' = lib.flatten fallbackAssocs;
+in
+{
+  sane.programs.mimeo = {
+    package = pkgs.mimeo.overridePythonAttrs (upstream: {
+      nativeBuildInputs = (upstream.nativeBuildInputs or []) ++ [
+        pkgs.copyDesktopItems
+      ];
+      desktopItems = [
+        (pkgs.makeDesktopItem {
+          name = "mimeo";
+          desktopName = "Mimeo";
+          exec = "mimeo %U";
+          comment = "Open files by MIME-type or file name using regular expressions.";
+        })
+      ];
+
+      # upstream mimeo doesn't run preInstall/postInstall hooks, but we need that for the .desktop file
+      installPhase = ''
+        runHook preInstall
+        ${upstream.installPhase}
+        runHook postInstall
+      '';
+
+      passthru = (upstream.passthru or {}) // {
+        inherit mimeo-open-desktop;
+      };
+    });
+
+    fs.".config/mimeo/associations.txt".symlink.text = lib.concatStringsSep "\n" (assocs' ++ fallbackAssocs');
+    mime.priority = 20;
+    mime.associations."x-scheme-handler/http" = "mimeo.desktop";
+    mime.associations."x-scheme-handler/https" = "mimeo.desktop";
+  };
+}

hosts/common/programs/mimeo/mimeo-open-desktop

@@ -0,0 +1,41 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -i python3 -p "python3.withPackages (ps: [  ])" -p mimeo
+
+# TODO: migrate nixpkgs mimeo to be `buildPythonPackage` to make it importable here.
+# see <doc/languages-frameworks/python.section.md>
+
+import subprocess
+import sys
+
+desktop = sys.argv[1]
+opener_args = sys.argv[2:]
+
+desktop_fields=subprocess.check_output([
+    "mimeo",
+    "--desk2field",
+    "Exec",
+    desktop
+]).decode('utf-8')
+# print(f"fields: {desktop_fields!r}")
+
+desktop_exec = '\n'.join(desktop_fields.split('\n')[1:])
+# print(f"exec: {desktop_exec!r}")
+
+# TODO: this is obviously not correct if any of the args included spaces
+desktop_argv = [f.strip() for f in desktop_exec.split(' ') if f.strip()]
+# print(f"desktop_argv: {desktop_argv!r}")
+
+# fields explained: <https://specifications.freedesktop.org/desktop-entry-spec/latest/ar01s07.html>
+# - %U = all URLs
+# - %U = just the first URL
+substituted_argv = []
+for arg in desktop_argv:
+    if arg == '%U':
+        substituted_argv += opener_args
+    elif arg == '%u':
+        substituted_argv += opener_args[:1]
+    else:
+        substituted_argv += [arg]
+
+# print(f"argv: {substituted_argv}")
+print(subprocess.check_output(substituted_argv).decode())

hosts/common/programs/mpv.nix

@@ -126,7 +126,7 @@ in
     mime.associations."video/quicktime" = "mpv.desktop";
     mime.associations."video/webm" = "mpv.desktop";
     mime.associations."video/x-matroska" = "mpv.desktop";
-    mime.urlAssociations."^https?://(www.)?youtube.com/watch\?.*v=" = "mpv --player-operation-mode=pseudo-gui -- %U";
+    mime.urlAssociations."^https?://(www.)?youtube.com/watch\?.*v=" = "mpv.desktop";
   };
 }