Add m_archives and getArchiveById to Library

These members will mirror the functionality offered by equivalent usage
of Reader class.

include/library.h

@@ -24,6 +24,7 @@
 #include <vector>
 #include <map>
 #include <memory>
+#include <zim/archive.h>
 
 #include "book.h"
 #include "bookmark.h"
@@ -146,6 +147,7 @@ class Library
 {
   std::map<std::string, kiwix::Book> m_books;
   std::map<std::string, std::shared_ptr<Reader>> m_readers;
+  std::map<std::string, std::shared_ptr<zim::Archive>> m_archives;
   std::vector<kiwix::Bookmark> m_bookmarks;
   class BookDB;
   std::unique_ptr<BookDB> m_bookDB;
@@ -198,6 +200,7 @@ class Library
   const Book& getBookByPath(const std::string& path) const;
   Book& getBookByPath(const std::string& path);
   std::shared_ptr<Reader> getReaderById(const std::string& id);
+  std::shared_ptr<zim::Archive> getArchiveById(const std::string& id);
 
   /**
    * Remove a book from the library.

include/reader.h

@@ -91,6 +91,13 @@ class Reader
    *                    (.zim extesion).
    */
   explicit Reader(const string zimFilePath);
+
+   /**
+   * Create a Reader to read a zim file given by the Archive.
+   *
+   * @param archive The shared pointer to the Archive object.
+   */
+  explicit Reader(const std::shared_ptr<zim::Archive> archive);
 #ifndef _WIN32
   explicit Reader(int fd);
   Reader(int fd, zim::offset_type offset, zim::size_type size);
@@ -488,7 +495,7 @@ class Reader
   zim::Archive* getZimArchive() const;
 
  protected:
-  std::unique_ptr<zim::Archive> zimArchive;
+  std::shared_ptr<zim::Archive> zimArchive;
   std::string zimFilePath;
 
   SuggestionsList_t suggestions;

src/library.cpp

@@ -108,6 +108,7 @@ bool Library::removeBookById(const std::string& id)
 {
   m_bookDB->delete_document("Q" + id);
   m_readers.erase(id);
+  m_archives.erase(id);
   return m_books.erase(id) == 1;
 }
 
@@ -146,11 +147,35 @@ std::shared_ptr<Reader> Library::getReaderById(const std::string& id)
     return m_readers.at(id);
   } catch (std::out_of_range& e) {}
 
+  try {
+    auto reader = make_shared<Reader>(m_archives.at(id));
+    m_readers[id] = reader;
+    return reader;
+  } catch (std::out_of_range& e) {}
+
   auto book = getBookById(id);
   if (!book.isPathValid())
     return nullptr;
-  auto sptr = make_shared<Reader>(book.getPath());
-  m_readers[id] = sptr;
+
+  auto archive = make_shared<zim::Archive>(book.getPath());
+  m_archives[id] = archive;
+  auto reader = make_shared<Reader>(archive);
+  m_readers[id] = reader;
+  return reader;
+}
+
+std::shared_ptr<zim::Archive> Library::getArchiveById(const std::string& id)
+{
+  try {
+    return m_archives.at(id);
+  } catch (std::out_of_range& e) {}
+
+  auto book = getBookById(id);
+  if (!book.isPathValid())
+    return nullptr;
+
+  auto sptr = make_shared<zim::Archive>(book.getPath());
+  m_archives[id] = sptr;
   return sptr;
 }
 

src/reader.cpp

@@ -86,6 +86,11 @@ Reader::Reader(const string zimFilePath)
   srand(time(nullptr));
 }
 
+Reader::Reader(const std::shared_ptr<zim::Archive> archive)
+  : zimArchive(archive),
+    zimFilePath(archive->getFilename())
+  {}
+
 #ifndef _WIN32
 Reader::Reader(int fd)
   :  zimArchive(new zim::Archive(fd)),