# -*- coding: utf-8 -*-
"""
    sphinx.builders.linkcheck
    ~~~~~~~~~~~~~~~~~~~~~~~~~

    The CheckExternalLinksBuilder class.

    :copyright: Copyright 2007-2016 by the Sphinx team, see AUTHORS.
    :license: BSD, see LICENSE for details.
"""

import re
import socket
import codecs
import threading
from os import path

from requests.exceptions import HTTPError
from six.moves import queue
from six.moves.urllib.parse import unquote
from six.moves.html_parser import HTMLParser
from docutils import nodes

# 2015-06-25 barry@python.org.  This exception was deprecated in Python 3.3 and
# removed in Python 3.5, however for backward compatibility reasons, we're not
# going to just remove it.  If it doesn't exist, define an exception that will
# never be caught but leaves the code in check_anchor() intact.
try:
    from six.moves.html_parser import HTMLParseError
except ImportError:
    class HTMLParseError(Exception):
        pass

from sphinx.builders import Builder
from sphinx.util import encode_uri, requests
from sphinx.util.console import purple, red, darkgreen, darkgray, \
    darkred, turquoise
from sphinx.util.requests import is_ssl_error


class AnchorCheckParser(HTMLParser):
    """Specialized HTML parser that looks for a specific anchor."""

    def __init__(self, search_anchor):
        HTMLParser.__init__(self)

        self.search_anchor = search_anchor
        self.found = False

    def handle_starttag(self, tag, attrs):
        for key, value in attrs:
            if key in ('id', 'name') and value == self.search_anchor:
                self.found = True
                break


def check_anchor(response, anchor):
    """Reads HTML data from a response object `response` searching for `anchor`.
    Returns True if anchor was found, False otherwise.
    """
    parser = AnchorCheckParser(anchor)
    try:
        # Read file in chunks. If we find a matching anchor, we break
        # the loop early in hopes not to have to download the whole thing.
        for chunk in response.iter_content(chunk_size=4096, decode_unicode=True):
            parser.feed(chunk)
            if parser.found:
                break
        parser.close()
    except HTMLParseError:
        # HTMLParser is usually pretty good with sloppy HTML, but it tends to
        # choke on EOF. But we're done then anyway.
        pass
    return parser.found


class CheckExternalLinksBuilder(Builder):
    """
    Checks for broken external links.
    """
    name = 'linkcheck'

    def init(self):
        self.to_ignore = [re.compile(x) for x in self.app.config.linkcheck_ignore]
        self.anchors_ignore = [re.compile(x)
                               for x in self.app.config.linkcheck_anchors_ignore]
        self.good = set()
        self.broken = {}
        self.redirected = {}
        # set a timeout for non-responding servers
        socket.setdefaulttimeout(5.0)
        # create output file
        open(path.join(self.outdir, 'output.txt'), 'w').close()

        # create queues and worker threads
        self.wqueue = queue.Queue()
        self.rqueue = queue.Queue()
        self.workers = []
        for i in range(self.app.config.linkcheck_workers):
            thread = threading.Thread(target=self.check_thread)
            thread.setDaemon(True)
            thread.start()
            self.workers.append(thread)

    def check_thread(self):
        kwargs = {}
        if self.app.config.linkcheck_timeout:
            kwargs['timeout'] = self.app.config.linkcheck_timeout

        kwargs['allow_redirects'] = True

        def check_uri():
            # split off anchor
            if '#' in uri:
                req_url, anchor = uri.split('#', 1)
                for rex in self.anchors_ignore:
                    if rex.match(anchor):
                        anchor = None
                        break
            else:
                req_url = uri
                anchor = None

            # handle non-ASCII URIs
            try:
                req_url.encode('ascii')
            except UnicodeError:
                req_url = encode_uri(req_url)

            try:
                if anchor and self.app.config.linkcheck_anchors:
                    # Read the whole document and see if #anchor exists
                    response = requests.get(req_url, stream=True, config=self.app.config,
                                            **kwargs)
                    found = check_anchor(response, unquote(anchor))

                    if not found:
                        raise Exception("Anchor '%s' not found" % anchor)
                else:
                    try:
                        # try a HEAD request first, which should be easier on
                        # the server and the network
                        response = requests.head(req_url, config=self.app.config, **kwargs)
                        response.raise_for_status()
                    except HTTPError as err:
                        # retry with GET request if that fails, some servers
                        # don't like HEAD requests.
                        response = requests.get(req_url, stream=True, config=self.app.config,
                                                **kwargs)
                        response.raise_for_status()
            except HTTPError as err:
                if err.response.status_code == 401:
                    # We'll take "Unauthorized" as working.
                    return 'working', ' - unauthorized', 0
                else:
                    return 'broken', str(err), 0
            except Exception as err:
                if is_ssl_error(err):
                    return 'ignored', str(err), 0
                else:
                    return 'broken', str(err), 0
            if response.url.rstrip('/') == req_url.rstrip('/'):
                return 'working', '', 0
            else:
                new_url = response.url
                if anchor:
                    new_url += '#' + anchor
                # history contains any redirects, get last
                if response.history:
                    code = response.history[-1].status_code
                return 'redirected', new_url, code

        def check():
            # check for various conditions without bothering the network
            if len(uri) == 0 or uri.startswith(('#', 'mailto:', 'ftp:')):
                return 'unchecked', '', 0
            elif not uri.startswith(('http:', 'https:')):
                return 'local', '', 0
            elif uri in self.good:
                return 'working', 'old', 0
            elif uri in self.broken:
                return 'broken', self.broken[uri], 0
            elif uri in self.redirected:
                return 'redirected', self.redirected[uri][0], self.redirected[uri][1]
            for rex in self.to_ignore:
                if rex.match(uri):
                    return 'ignored', '', 0

            # need to actually check the URI
            for _ in range(self.app.config.linkcheck_retries):
                status, info, code = check_uri()
                if status != "broken":
                    break

            if status == "working":
                self.good.add(uri)
            elif status == "broken":
                self.broken[uri] = info
            elif status == "redirected":
                self.redirected[uri] = (info, code)

            return (status, info, code)

        while True:
            uri, docname, lineno = self.wqueue.get()
            if uri is None:
                break
            status, info, code = check()
            self.rqueue.put((uri, docname, lineno, status, info, code))

    def process_result(self, result):
        uri, docname, lineno, status, info, code = result
        if status == 'unchecked':
            return
        if status == 'working' and info == 'old':
            return
        if lineno:
            self.info('(line %4d) ' % lineno, nonl=1)
        if status == 'ignored':
            if info:
                self.info(darkgray('-ignored- ') + uri + ': ' + info)
            else:
                self.info(darkgray('-ignored- ') + uri)
        elif status == 'local':
            self.info(darkgray('-local-   ') + uri)
            self.write_entry('local', docname, lineno, uri)
        elif status == 'working':
            self.info(darkgreen('ok        ')  + uri + info)
        elif status == 'broken':
            self.write_entry('broken', docname, lineno, uri + ': ' + info)
            if self.app.quiet or self.app.warningiserror:
                self.warn('broken link: %s (%s)' % (uri, info),
                          '%s:%s' % (self.env.doc2path(docname), lineno))
            else:
                self.info(red('broken    ') + uri + red(' - ' + info))
        elif status == 'redirected':
            text, color = {
                301: ('permanently', darkred),
                302: ('with Found', purple),
                303: ('with See Other', purple),
                307: ('temporarily', turquoise),
                0:   ('with unknown code', purple),
            }[code]
            self.write_entry('redirected ' + text, docname, lineno,
                             uri + ' to ' + info)
            self.info(color('redirect  ') + uri + color(' - ' + text + ' to '  + info))

    def get_target_uri(self, docname, typ=None):
        return ''

    def get_outdated_docs(self):
        return self.env.found_docs

    def prepare_writing(self, docnames):
        return

    def write_doc(self, docname, doctree):
        self.info()
        n = 0
        for node in doctree.traverse(nodes.reference):
            if 'refuri' not in node:
                continue
            uri = node['refuri']
            lineno = None
            while lineno is None:
                node = node.parent
                if node is None:
                    break
                lineno = node.line
            self.wqueue.put((uri, docname, lineno), False)
            n += 1
        done = 0
        while done < n:
            self.process_result(self.rqueue.get())
            done += 1

        if self.broken:
            self.app.statuscode = 1

    def write_entry(self, what, docname, line, uri):
        output = codecs.open(path.join(self.outdir, 'output.txt'), 'a', 'utf-8')
        output.write("%s:%s: [%s] %s\n" % (self.env.doc2path(docname, None),
                                           line, what, uri))
        output.close()

    def finish(self):
        for worker in self.workers:
            self.wqueue.put((None, None, None), False)


def setup(app):
    app.add_builder(CheckExternalLinksBuilder)

    app.add_config_value('linkcheck_ignore', [], None)
    app.add_config_value('linkcheck_retries', 1, None)
    app.add_config_value('linkcheck_timeout', None, None, [int])
    app.add_config_value('linkcheck_workers', 5, None)
    app.add_config_value('linkcheck_anchors', True, None)
    # Anchors starting with ! are ignored since they are
    # commonly used for dynamic pages
    app.add_config_value('linkcheck_anchors_ignore', ["^!"], None)
