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#!/usr/bin/env python
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"""
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Update searx/data/external_bangs.json using the duckduckgo bangs.
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https://duckduckgo.com/newbang loads
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* a javascript which provides the bang version ( https://duckduckgo.com/bv1.js )
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* a JSON file which contains the bangs ( https://duckduckgo.com/bang.v260.js for example )
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This script loads the javascript, then the bangs.
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The javascript URL may change in the future ( for example https://duckduckgo.com/bv2.js ),
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but most probably it will requires to update RE_BANG_VERSION
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"""
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# pylint: disable=C0116
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import json
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import re
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from os.path import join
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import requests
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from searx import searx_dir # pylint: disable=E0401 C0413
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# from https://duckduckgo.com/newbang
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URL_BV1 = 'https://duckduckgo.com/bv1.js'
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RE_BANG_VERSION = re.compile(r'\/bang\.v([0-9]+)\.js')
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HTTPS_COLON = 'https:'
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HTTP_COLON = 'http:'
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def get_bang_url():
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response = requests.get(URL_BV1)
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response.raise_for_status()
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r = RE_BANG_VERSION.findall(response.text)
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return f'https://duckduckgo.com/bang.v{r[0]}.js', r[0]
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def fetch_ddg_bangs(url):
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response = requests.get(url)
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response.raise_for_status()
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return json.loads(response.content.decode())
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def merge_when_no_leaf(node):
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"""Minimize the number of nodes
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A -> B -> C
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B is child of A
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C is child of B
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If there are no C equals to '*', then each C are merged into A
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For example:
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d -> d -> g -> * (ddg*)
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-> i -> g -> * (dig*)
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becomes
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d -> dg -> *
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-> ig -> *
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"""
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restart = False
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if not isinstance(node, dict):
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return
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# create a copy of the keys so node can be modified
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keys = list(node.keys())
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for key in keys:
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if key == '*':
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continue
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value = node[key]
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value_keys = list(value.keys())
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if '*' not in value_keys:
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for value_key in value_keys:
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node[key + value_key] = value[value_key]
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merge_when_no_leaf(node[key + value_key])
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del node[key]
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restart = True
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else:
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merge_when_no_leaf(value)
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if restart:
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merge_when_no_leaf(node)
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def optimize_leaf(parent, parent_key, node):
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if not isinstance(node, dict):
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return
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if len(node) == 1 and '*' in node and parent is not None:
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parent[parent_key] = node['*']
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else:
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for key, value in node.items():
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optimize_leaf(node, key, value)
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def parse_ddg_bangs(ddg_bangs):
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bang_trie = {}
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bang_urls = {}
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for bang_definition in ddg_bangs:
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# bang_list
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bang_url = bang_definition['u']
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if '{{{s}}}' not in bang_url:
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# ignore invalid bang
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continue
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bang_url = bang_url.replace('{{{s}}}', chr(2))
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# only for the https protocol: "https://example.com" becomes "//example.com"
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if bang_url.startswith(HTTPS_COLON + '//'):
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bang_url = bang_url[len(HTTPS_COLON):]
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#
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if bang_url.startswith(HTTP_COLON + '//') and bang_url[len(HTTP_COLON):] in bang_urls:
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# if the bang_url uses the http:// protocol, and the same URL exists in https://
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# then reuse the https:// bang definition. (written //example.com)
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bang_def_output = bang_urls[bang_url[len(HTTP_COLON):]]
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else:
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# normal use case : new http:// URL or https:// URL (without "https:", see above)
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bang_rank = str(bang_definition['r'])
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bang_def_output = bang_url + chr(1) + bang_rank
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bang_def_output = bang_urls.setdefault(bang_url, bang_def_output)
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bang_urls[bang_url] = bang_def_output
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# bang name
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bang = bang_definition['t']
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# bang_trie
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t = bang_trie
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for bang_letter in bang:
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t = t.setdefault(bang_letter, {})
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t = t.setdefault('*', bang_def_output)
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# optimize the trie
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merge_when_no_leaf(bang_trie)
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optimize_leaf(None, None, bang_trie)
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return bang_trie
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def get_bangs_filename():
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return join(join(searx_dir, "data"), "external_bangs.json")
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if __name__ == '__main__':
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bangs_url, bangs_version = get_bang_url()
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print(f'fetch bangs from {bangs_url}')
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output = {
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'version': bangs_version,
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'trie': parse_ddg_bangs(fetch_ddg_bangs(bangs_url))
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}
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with open(get_bangs_filename(), 'w') as fp:
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json.dump(output, fp, ensure_ascii=False, indent=4)
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