[docs] update_external_bangs.py - implement script to document bangs

Function 'write_external_bang_doc(..)' generates documentation of the external
bangs in folder 'docs/admin/external_bang'.  Ducumentation will be update when
external bangs are updated::

    ./manage pyenv.cmd searx_extra/update/update_external_bangs.py

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx_extra/update/update_external_bangs.py

@@ -3,7 +3,8 @@
 """
 Update searx/data/external_bangs.json using the duckduckgo bangs.
 
-https://duckduckgo.com/newbang loads
+https://duckduckgo.com/newbang loads:
+
 * a javascript which provides the bang version ( https://duckduckgo.com/bv1.js )
 * a JSON file which contains the bangs ( https://duckduckgo.com/bang.v260.js for example )
 
@@ -14,14 +15,18 @@ but most probably it will requires to update RE_BANG_VERSION
 """
 # pylint: disable=C0116
 
+import sys
 import json
 import re
-from os.path import join
 
 import httpx
+from fspath import FSPath
 
 from searx import searx_dir  # pylint: disable=E0401 C0413
-
+from searx.external_bang import (
+    get_bang_definition_and_ac,
+    resolve_bang_definition,
+)
 
 # from https://duckduckgo.com/newbang
 URL_BV1 = 'https://duckduckgo.com/bv1.js'
@@ -100,6 +105,7 @@ def optimize_leaf(parent, parent_key, node):
 def parse_ddg_bangs(ddg_bangs):
     bang_trie = {}
     bang_urls = {}
+    bang_doc = {}
 
     for bang_definition in ddg_bangs:
         # bang_list
@@ -129,6 +135,7 @@ def parse_ddg_bangs(ddg_bangs):
 
         # bang name
         bang = bang_definition['t']
+        bang_doc[bang] = (bang_url, bang_definition)
 
         # bang_trie
         t = bang_trie
@@ -140,19 +147,159 @@ def parse_ddg_bangs(ddg_bangs):
     merge_when_no_leaf(bang_trie)
     optimize_leaf(None, None, bang_trie)
 
-    return bang_trie
+    return bang_trie, bang_doc
 
 
-def get_bangs_filename():
-    return join(join(searx_dir, "data"), "external_bangs.json")
+def sort_by_category(bang_doc):
+
+    ret_val = {}
+    for bang_name, (bang_url, bang_definition) in bang_doc.items():
+
+        # add category
+        categ = bang_definition.get('c', 'no category')
+        ret_val[categ] = ret_val.get(categ, {})
+
+        # add sub-category
+        sub_categ = bang_definition.get('sc', 'no sub-category')
+        ret_val[categ][sub_categ] = ret_val[categ].get(sub_categ, {})
+
+        # add bang name to sub-category dict and set tuple: bang_url,
+        # bang_definition
+        ret_val[categ][sub_categ][bang_name] = bang_url, bang_definition
+
+    return ret_val
+
+FILE_INTRO = """\
+.. Do not edit this file, this file was created by:
+..
+..     ./manage pyenv.cmd searx_extra/update/update_external_bangs.py
+"""
+
+CATEGORY_INDEX="""
+.. toctree::
+   :maxdepth: 2
+   :caption: Contents
+   :glob:
+"""
+
+TABLE_INTRO = """
+.. flat-table:: Bangs in *{categ_name} / {sub_categ_name}*
+   :header-rows: 1
+   :stub-columns: 1
+   :widths: 2 1 4 6
+
+   * - Bang
+     - Rank
+     - Description
+     - URL
+"""
+
+TABLE_ROW = """
+   * - `!!{bang_name} <{url}>`__
+     - {rank}
+     - {bang_description}
+     - ``{url}``
+"""
+
+def write_external_bang_doc(external_bangs_db, bang_doc):
+    """Generate documentation of the external bangs in
+    ``docs/admin/external_bang``.
+
+    """
+    # pylint: disable=too-many-locals
+    def rst_title(name, tag="=", topline=True):
+        ret_val = "\n%s" % (name,)
+        if topline:
+            ret_val = "\n" + len(name) * tag + ret_val
+        ret_val += "\n" + len(name) * tag + "\n"
+        return ret_val
+
+    def get_valid_filename(fname):
+        fname = str(fname).strip().replace(' ', '_')
+        return re.sub(r'(?u)[^-\w.]', '', fname)
+
+    folder = FSPath(searx_dir + "/../docs/admin/external_bang")
+    print(f're-create external bang documentation in: {folder}')
+    folder.delete()
+    folder.makedirs()
+
+    bang_doc = sort_by_category(bang_doc)
+    categ_list = list(bang_doc)
+    categ_list.sort(key=lambda v: v.lower())
+
+    for categ_name in categ_list:
+        categ = bang_doc[categ_name]
+
+        # for each category create on folder with index.rst in
+
+        categ_folder = folder / get_valid_filename(categ_name)
+        categ_folder.makedirs()
+
+        sub_categ_list = list(categ)
+        sub_categ_list.sort(key=lambda v: v.lower())
+
+        fname = categ_folder / 'index.rst'
+        print(f"create file: {fname}")
+        with open(fname, 'w') as out:
+            out.write(FILE_INTRO.format(**locals()))
+            out.write(rst_title(categ_name, topline=True))
+            out.write(CATEGORY_INDEX.format(**locals()))
+            for sub_categ_name in sub_categ_list:
+                out.write("\n   %s" % get_valid_filename(sub_categ_name))
+
+        for sub_categ_name in sub_categ_list:
+            sub_categ = categ[sub_categ_name]
+
+            # for each sub-category create on reST-file
+
+            fname = categ_folder / get_valid_filename(sub_categ_name + ".rst")
+            print(f"create file: {fname}")
+            with open(fname, 'w') as out:
+                out.write(FILE_INTRO.format(**locals()))
+                out.write(rst_title(sub_categ_name))
+                out.write(TABLE_INTRO.format(**locals()))
+
+                bang_name_list = list(sub_categ)
+                bang_name_list.sort(key=lambda v: v.lower())
+
+                # for each bang create on table row
+
+                for bang_name in bang_name_list:
+                    # pylint: disable=possibly-unused-variable
+                    bang_url, bang_definition =  sub_categ[bang_name]
+                    bang_description = bang_definition.get('s','...')
+                    bang_node, bang_ac_list = get_bang_definition_and_ac(external_bangs_db, bang_name)
+                    bang_ac_list = ', '.join(bang_ac_list) or '...'
+
+                    try:
+                        url, rank = resolve_bang_definition(bang_node, '')
+                        url = url.strip()
+                    except AttributeError:
+                        # There is one defect entry in external_bangs_db where
+                        # the bang_node is a dict and not a string ... why?
+                        sys.stderr.write("ignore error with bang:: '%s'\n" % (bang_node, ))
+                        continue
+
+                    out.write(TABLE_ROW.format(**locals()))
 
 
 if __name__ == '__main__':
-    bangs_url, bangs_version = get_bang_url()
-    print(f'fetch bangs from {bangs_url}')
-    output = {
-        'version': bangs_version,
-        'trie': parse_ddg_bangs(fetch_ddg_bangs(bangs_url))
+
+    _bangs_url, _bangs_version = get_bang_url()
+
+    print(f'fetch & parse bangs from {_bangs_url}')
+    _bang_trie, _bang_doc = parse_ddg_bangs(fetch_ddg_bangs(_bangs_url))
+
+    # generate JSON file for: searx.data.EXTERNAL_BANGS
+
+    _fname = FSPath(searx_dir + "/data/external_bangs.json")
+    print(f'update file: {_fname}')
+    _external_bangs_db = {
+        'version': _bangs_version,
+        'trie': _bang_trie,
     }
-    with open(get_bangs_filename(), 'w') as fp:
-        json.dump(output, fp, ensure_ascii=False, indent=4)
+    with open(_fname, 'w') as fp:
+        json.dump(_external_bangs_db, fp, ensure_ascii=False, indent=4)
+
+    # generate documentation
+    write_external_bang_doc(_external_bangs_db, _bang_doc)