From 3273ab150cbf5a4b328f12f935da5653a896ff2e Mon Sep 17 00:00:00 2001
From: Nicolas Pourcelot <nicolas.pourcelot@gmail.com>
Date: Tue, 12 Dec 2023 08:57:59 +0100
Subject: [PATCH] feat: implement new option `same-number-of-pages-compact`.

---
 ptyx/compilation.py         | 35 +++++++++++++++++++++++++++++++----
 ptyx/compilation_options.py |  1 +
 ptyx/script.py              | 14 ++++++++++++++
 3 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/ptyx/compilation.py b/ptyx/compilation.py
index 1cb1145..ae86858 100644
--- a/ptyx/compilation.py
+++ b/ptyx/compilation.py
@@ -84,6 +84,13 @@ def directory(self) -> Path:
     def __len__(self):
         return len(self.info_dict)
 
+    def __getitem__(self, item: DocId | slice):
+        if isinstance(item, slice):
+            info_dict = {key: self.info_dict[key] for key in list(self.info_dict)[item]}
+            return MultipleFilesCompilationInfo(basename=self.basename, info_dict=info_dict)
+        else:
+            return self.info_dict[item]
+
 
 class _LoggedStream(object):
     """Add logging to a data stream, like stdout or stderr.
@@ -291,7 +298,7 @@ def make_files(
                     # Pages number is set manually, and don't match.
                     print(f"Warning: skipping {info.src} (incorrect page number) !")
                     continue
-                elif options.same_number_of_pages:
+                elif options.same_number_of_pages or options.same_number_of_pages_compact:
                     # Determine automatically the best fixed page count.
                     # This is a bit subtle. We want all compiled documents to have
                     # the same pages number, yet we don't want to set it manually.
@@ -310,9 +317,29 @@ def make_files(
 
             all_compilation_info.info_dict[doc_id] = info
             doc_id = DocId(doc_id + 1)
-        for compil_info in pages_per_document.values():
-            if len(compil_info.doc_ids) > len(all_compilation_info.doc_ids):
-                all_compilation_info = compil_info
+        if options.same_number_of_pages_compact:
+            # In compact mode, we try to minimize the number of pages of the generated documents.
+            # To not increase too drastically the time of compilation, we adopt the following heuristic:
+            # we'll use the shorter documents, if their frequency exceed 25% of the total documents.
+            total = sum(len(compil_info.doc_ids) for compil_info in pages_per_document.values())
+            for page_count in sorted(pages_per_document):
+                if len(pages_per_document[page_count].doc_ids) > total / 4:
+                    all_compilation_info = pages_per_document[page_count]
+                    break
+            else:
+                # Exceptionally, if the length of each document is highly variable, each page count value
+                # may occur less than 25%. Then, we'll select the most frequent page count.
+                for compil_info in pages_per_document.values():
+                    if len(compil_info.doc_ids) > len(all_compilation_info.doc_ids):
+                        all_compilation_info = compil_info
+
+            if len(all_compilation_info) > target:
+                all_compilation_info = all_compilation_info[:target]
+
+        elif options.same_number_of_pages:
+            for compil_info in pages_per_document.values():
+                if len(compil_info.doc_ids) > len(all_compilation_info.doc_ids):
+                    all_compilation_info = compil_info
 
     assert len(all_compilation_info) == target, len(all_compilation_info)
     filenames = all_compilation_info.pdf_paths
diff --git a/ptyx/compilation_options.py b/ptyx/compilation_options.py
index b0685a0..85ab203 100644
--- a/ptyx/compilation_options.py
+++ b/ptyx/compilation_options.py
@@ -18,6 +18,7 @@ class CompilationOptions:
     reorder_pages: Literal["brochure", "brochure-reversed", ""] = ""
     set_number_of_pages: int = 0
     same_number_of_pages: bool = False
+    same_number_of_pages_compact: bool = False
     no_correction: bool = False
     no_pdf: bool = False
     view: bool = False
diff --git a/ptyx/script.py b/ptyx/script.py
index 15fa57a..47a99fa 100644
--- a/ptyx/script.py
+++ b/ptyx/script.py
@@ -146,6 +146,20 @@ def __init__(self):
                 " number of documents is always respected, contrary to `--set-number-of-pages` option."
             ),
         )
+        group2.add_argument(
+            "-sc",
+            "--same-number-of-pages-compact",
+            action="store_true",
+            help=(
+                "Ensure that all documents have the same number of pages."
+                " Since the number of pages is automatically set, the requested"
+                " number of documents is always respected, contrary to `--set-number-of-pages` option."
+                " Try to minimize the number of pages per document."
+                " Note that this may increase significantly compilation time,"
+                " compared to `--same-number-of-pages` option"
+                " (the compilation may be up to 2 times slower)."
+            ),
+        )
         self.add_argument(
             "-nc",
             "--no-correction",