From 8470b1794d3c1fcc84991cde150569d2031b3133 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sun, 19 Jun 2016 09:40:13 +0530
Subject: [PATCH] Implement <dc:language>

---
 src/calibre/ebooks/metadata/opf3.py      | 42 +++++++++++++++++++++++-
 src/calibre/ebooks/metadata/opf3_test.py | 14 +++++++-
 2 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/src/calibre/ebooks/metadata/opf3.py b/src/calibre/ebooks/metadata/opf3.py
index 9c9a4d9c08..52ca95eede 100644
--- a/src/calibre/ebooks/metadata/opf3.py
+++ b/src/calibre/ebooks/metadata/opf3.py
@@ -12,8 +12,9 @@ from lxml import etree
 
 from calibre.ebooks.metadata import check_isbn
 from calibre.ebooks.metadata.book.base import Metadata
-from calibre.ebooks.metadata.utils import parse_opf, pretty_print_opf, ensure_unique
+from calibre.ebooks.metadata.utils import parse_opf, pretty_print_opf, ensure_unique, normalize_languages
 from calibre.ebooks.oeb.base import OPF2_NSMAP, OPF, DC
+from calibre.utils.localization import canonicalize_lang
 
 # Utils {{{
 # http://www.idpf.org/epub/vocab/package/pfx/
@@ -31,6 +32,13 @@ reserved_prefixes = {
 _xpath_cache = {}
 _re_cache = {}
 
+def uniq(vals):
+    ''' Remove all duplicates from vals, while preserving order.  '''
+    vals = vals or ()
+    seen = set()
+    seen_add = seen.add
+    return list(x for x in vals if x not in seen and not seen_add(x))
+
 def XPath(x):
     try:
         return _xpath_cache[x]
@@ -268,6 +276,36 @@ def set_title(root, prefixes, refines, title, title_sort=None):
     main_title.text = title or None
     ts = [refdef('file-as', title_sort)] if title_sort else ()
     set_refines(main_title, refines, refdef('title-type', 'main'), *ts)
+    for m in XPath('./opf:metadata/opf:meta[@name="calibre:title_sort"]')(root):
+        remove_element(m, refines)
+
+# }}}
+
+# Languages {{{
+def read_languages(root, prefixes, refines):
+    ans = []
+    for lang in XPath('./opf:metadata/dc:language')(root):
+        val = canonicalize_lang((lang.text or '').strip())
+        if val and val not in ans and val != 'und':
+            ans.append(val)
+    return uniq(ans)
+
+def set_languages(root, prefixes, refines, languages):
+    opf_languages = []
+    for lang in XPath('./opf:metadata/dc:language')(root):
+        remove_element(lang, refines)
+        val = (lang.text or '').strip()
+        if val:
+            opf_languages.append(val)
+    languages = filter(lambda x: x and x != 'und', normalize_languages(opf_languages, languages))
+    if not languages:
+        # EPUB spec says dc:language is required
+        languages = ['und']
+    metadata = XPath('./opf:metadata')(root)[0]
+    for lang in uniq(languages):
+        l = metadata.makeelement(DC('language'))
+        l.text = lang
+        metadata.append(l)
 
 # }}}
 
@@ -284,6 +322,7 @@ def read_metadata(root):
     ans.set_identifiers(ids)
     ans.title = read_title(root, prefixes, refines) or ans.title
     ans.title_sort = read_title_sort(root, prefixes, refines) or ans.title_sort
+    ans.languages = read_languages(root, prefixes, refines) or ans.languages
 
     return ans
 
@@ -295,6 +334,7 @@ def apply_metadata(root, mi, cover_prefix='', cover_data=None, apply_null=False,
     prefixes, refines = read_prefixes(root), read_refines(root)
     set_identifiers(root, prefixes, refines, mi.identifiers, force_identifiers=force_identifiers)
     set_title(root, prefixes, refines, mi.title, mi.title_sort)
+    set_languages(root, prefixes, refines, mi.languages)
 
     pretty_print_opf(root)
 
diff --git a/src/calibre/ebooks/metadata/opf3_test.py b/src/calibre/ebooks/metadata/opf3_test.py
index 6ca638df44..e1655498b0 100644
--- a/src/calibre/ebooks/metadata/opf3_test.py
+++ b/src/calibre/ebooks/metadata/opf3_test.py
@@ -12,7 +12,7 @@ from lxml import etree
 from calibre.ebooks.metadata.opf3 import (
     parse_prefixes, reserved_prefixes, expand_prefix, read_identifiers,
     read_metadata, set_identifiers, XPath, set_application_id, read_title,
-    read_refines, set_title, read_title_sort
+    read_refines, set_title, read_title_sort, read_languages, set_languages
 )
 
 TEMPLATE = '''<package xmlns="http://www.idpf.org/2007/opf" version="3.0" unique-identifier="uid"><metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opf="http://www.idpf.org/2007/opf">{metadata}</metadata></package>'''  # noqa
@@ -90,6 +90,18 @@ class TestOPF3(unittest.TestCase):
         self.ae(st(root, 'abc'), 'abc')
     # }}}
 
+    def test_languages(self):  # {{{
+        def rl(root):
+            return read_languages(root, reserved_prefixes, read_refines(root))
+        def st(root, languages):
+            set_languages(root, reserved_prefixes, read_refines(root), languages)
+            return rl(root)
+        root = self.get_opf('''<dc:language>en-US</dc:language><dc:language>fr</dc:language>''')
+        self.ae(['eng', 'fra'], rl(root))
+        self.ae(st(root, ['de', 'de', 'es']), ['deu', 'spa'])
+        self.ae(st(root, []), [])
+
+    # }}}
 # Run tests {{{
 
 class TestRunner(unittest.main):