feat(sterni/blërg): generic, configurable backends

Change-Id: Iebec5caea9b780eb8ca2ec1f18bb4fa978f4bb95
Reviewed-on: https://cl.tvl.fyi/c/depot/+/13107
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Autosubmit: sterni <sternenseemann@systemli.org>

users/sterni/blërg/README.md

@@ -3,6 +3,8 @@
 ## dependencies
 
 - [CBQN][] (other [BQN][] implementations may work, but are untested)
+- Marshall Lochbaum's [bqn-libs][] which blërg expects to find at the
+  location the `BQN_LIBS` environment variable points to.
 - //users/sterni/mn2html
 - [mblaze(7)][mblaze]
 - [execline][]
@@ -12,3 +14,4 @@
 [execline]: https://skarnet.org/software/execline/
 [BQN]: https://mlochbaum.github.io/BQN/
 [CBQN]: https://github.com/dzaima/cbqn
+[bqn-libs]: https://github.com/mlochbaum/bqn-libs/

users/sterni/blërg/blërg.bqn

@@ -1,5 +1,5 @@
 #!/usr/bin/env BQN
-# SPDX-FileCopyrightText: Copyright © 2024 sterni
+# SPDX-FileCopyrightText: Copyright © 2024-2025 sterni
 # SPDX-License-Identifier: GPL-3.0-only
 #
 # blërg is a reimplementation of mblog in BQN. BQN is used as a sort of bespoke
@@ -34,6 +34,21 @@ Run ← {
 R ← {𝕊 exit‿stdout‿stderr: stderr!0=exit ⋄ stdout}∘Run
 LR ← Lines∘R
 
+GetEnv ← {R "importas"‿"env"‿𝕩‿"printf"‿"%s"‿"$env"}
+
+RelPath ← •wdpath⊸•file.At
+
+# 3p dependencies
+
+j ← {
+  # Update README.md if dependency discovery changes
+  ⟨Parse⟩ ⇐ •Import (GetEnv "BQN_LIBS") •file.At "json.bqn"
+
+  # TODO(sterni): default value
+  ObjGet ⇐ (⊏⊸(⊑∘⊐) ⊑ ⊏˜⟜1)⟜<
+  ObjGetPath ⇐ ObjGet˜´⟜⌽
+}
+
 # (Apple) Mail Notes Backend
 
 # TODO(sterni): avoid argv limit by chunking
@@ -41,7 +56,8 @@ Hdrs ← {LR "mhdr"‿"-dh"‿(':' _join 𝕨)∾𝕩}
 Dates ← {ReadPosDec¨ LR "mhdr"‿"-Dh"‿"Date"∾𝕩}
 headerNames ← "X-Uniform-Type-Identifier"‿"X-Universally-Unique-Identifier"‿"Subject"
 
-MailNotesBackend ← {𝕊 mailDir:
+MailNotesBackend ← {𝕊 config:
+  mailDir ← RelPath config j.ObjGet "maildir"
   Entries ⇐ {𝕊:
     ms ← LR "mlist"‿mailDir
     th ← ⟨≠ms,≠headerNames⟩⥊headerNames Hdrs ms
@@ -55,6 +71,8 @@ MailNotesBackend ← {𝕊 mailDir:
   }
 }
 
+backends ← ⍉>⟨"mail-notes"‿mailNotesBackend⟩
+
 # Rendering
 
 RenderPage ← {
@@ -76,18 +94,26 @@ WriteEntry ← {outDir 𝕊 entry:
 
 # Main
 
-mailDir‿outDir ← {
+configFile‿outDir ← {
-  # Usage: blërg <maildir> <out dir>
+  # Usage: blërg <config file> <out dir>
   ! 2=≠•args
   # TODO(sterni): expand ~/
-  •wdpath⊸•file.At¨ •args
+  RelPath¨ •args
 }
 
-m ← MailNotesBackend mailDir
+config ← {
-entries ← (<"time") ((⍒∘(•ns.Get˜¨))⊏⊢) m.Entries @
+  raw ← j.Parse •FChars configFile
 
-title ← "blërg"
+  [bns,bcs] ← raw j.ObjGet "backends"
+  bcs ↩ bcs ∾˘⟜{2‿1⊸⥊"name"‿𝕩}¨ bns
+  bts ← (j.ObjGet⟜"type")˜¨ bcs
+  backends ⇐ bcs {𝕏 𝕨}¨ backends⊸j.ObjGet¨ bts
+
+  title ⇐ raw j.ObjGet "title"
+}
+
+entries ← (<"time") ((⍒∘(•ns.Get˜¨))⊏⊢) ∾{𝕩.Entries @}¨ config.backends
 
 MkDirP outDir
 entryIndex ← outDir⊸WriteEntry¨ entries
-(outDir •file.At "index.html") •file.Chars title RenderPage ∾"<ul>"∾entryIndex∾"</ul>"
+(outDir •file.At "index.html") •file.Chars config.title RenderPage ∾"<ul>"∾entryIndex∾"</ul>"

users/sterni/blërg/default.nix

@@ -5,13 +5,16 @@ let
   runtimeDependencies = [
     depot.users.sterni.mn2html
     pkgs.mblaze
-    pkgs.execline # execline-cd
+    pkgs.execline # execline-cd, importas
+    # coreutils   # for printf (assumed to be installed)
   ];
 
   # … and this
   buildInputs = [
     pkgs.cbqn
   ];
+
+  BQN_LIBS = depot.third_party.bqn-libs + "/lib";
 in
 
 pkgs.runCommandNoCC "blerg"
@@ -25,10 +28,13 @@ pkgs.runCommandNoCC "blerg"
   passthru.shell = pkgs.mkShell {
     name = "blërg-shell";
     packages = runtimeDependencies ++ buildInputs;
+    inherit BQN_LIBS;
   };
 }
   ''
     install -Dm755 "$src" "$out/bin/blërg"
     patchShebangs "$out/bin/blërg"
-    wrapProgram "$out/bin/blërg" --prefix PATH : "${lib.makeBinPath runtimeDependencies}"
+    wrapProgram "$out/bin/blërg" \
+      --prefix PATH : "${lib.makeBinPath runtimeDependencies}" \
+      --set BQN_LIBS "${BQN_LIBS}"
   ''