refactor(sterni/blërg): avoid calling mhdr once per header

We can actually get all the headers we are interested in just one call
of mhdr(1) since it can query multiple headers in multiple messages in
just one call. With BQNs reshape / two dimensional array facilities it
is easy to group the lines of headers by their originating message and
append the original path to the result array.

We still use a separate mhdr(1) call for the Date header since we rely
on the -D option for parsing the header.

Change-Id: Iaaf8f21fa22ab3e32e6900df4ae164e72c722cd3
Reviewed-on: https://cl.tvl.fyi/c/depot/+/13016
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Autosubmit: sterni <sternenseemann@systemli.org>

users/sterni/blërg/blërg.bqn

@@ -17,16 +17,15 @@ MkDirP ← •file.CreateDir⍟(¬•file.Exists)
 
 AsciiDown ← ('A'-'a')⊸(⊢-×⟜('A'⊸≤∧≤⟜'Z'))
 
-nl ← @+10
+_join ← {(∾⟜(𝕗⊸∾))´𝕩;𝕨∾𝕗∾𝕩}
 
+nl ← @+10
 SplitChar ← ((=(¯1˙⍟⊣)¨+`∘=)⊔⊢)
 Lines ← nl⊸SplitChar
 
 ReadPosInt ← {(𝕨⊸×+⊣)´∘⌽-⟜'0'𝕩} # ty leah2
 ReadPosDec ← 10⊸ReadPosInt
 
-ApplyMany ← {fs 𝕊 arg: {𝕏 arg}¨ fs}
-
 Chomp ← {⟨nl⟩≡¯1↑𝕩? ¯1↓𝕩; 𝕩}
 
 Run ← {
@@ -43,16 +42,20 @@ LR ← Lines∘R
 # (Apple) Mail Notes Backend
 
 # TODO(sterni): avoid argv limit by chunking
-Hdr ← {LR "mhdr"‿"-dh"‿𝕨∾𝕩}
-Date ← {ReadPosDec¨ LR "mhdr"‿"-Dh"‿"Date"∾𝕩}
+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:
-  Filter ← {𝕩 ("com.apple.mail-note"⊸≡¨/⊣) "X-Uniform-Type-Identifier" Hdr 𝕩}
-  Id ← AsciiDown "X-Universally-Unique-Identifier"⊸Hdr
-  Title ← "Subject"⊸Hdr
-  MkRenderer ← {𝕊 p: {R "execline-cd"‿𝕩‿"mshow"‿"-x"‿p ⋄ R "mn2html"‿p}}
-  # TODO(sterni): entries could become namespaces
-  Entries ⇐ {𝕊: ⍉>⟨Id,Title,Date,MkRenderer¨⟩⊸ApplyMany Filter LR "mlist"‿mailDir}
+  Entries ⇐ {𝕊:
+    ms ← LR "mlist"‿mailDir
+    th ← ⍉⟨≠ms,≠headerNames⟩⥊headerNames Hdrs ms
+    dh ← Dates ms
+    ah ← (("com.apple.mail-note"⊸≡⊑)˘/⊢) ⍉th∾dh≍ms
+    {𝕊 ·‿id‿title‿date‿path:
+      ⟨AsciiDown id, title, date, {"execline-cd"‿𝕩‿"mshow"‿"-x"‿path ⋄ R "mn2html"‿path}⟩
+    }˘ ah
+  }
 }
 
 # Rendering

users/sterni/exercises/aoc/lib.bqn

@@ -19,3 +19,5 @@ Xor ⇐ (¬⊸∧∨∧⟜¬)
 
 # To get all Diagonals (⊢∾○Diagonals⌽)
 Diagonals ⇐ {(0‿0⊸⍉ ↓⟜𝕩)¨ (↕≠𝕩)}
+
+ApplyMany ← {fs 𝕊 arg: {𝕏 arg}¨ fs}