#!/usr/bin/python3


# @todo logging
# @todo sort by last_changed
# @todo extra options for url like , verify=False etc.
# @todo enable https://urllib3.readthedocs.io/en/latest/user-guide.html#ssl as option?
# @todo maybe a button to reset all 'last-changed'.. so you can see it clearly when something happens since your last visit
# @todo option for interval day/6 hour/etc
# @todo on change detected, config for calling some API
# @todo make tables responsive!
# @todo fetch title into json
# https://distill.io/features
# proxy per check
#i
import json
import eventlet
import eventlet.wsgi

import time
import os
import getopt
import sys
import datetime
import timeago

import threading
import queue


from flask import Flask, render_template, request, send_file, send_from_directory, safe_join, abort, redirect, url_for


# Local
import store
import fetch_site_status
running_update_threads = []
ticker_thread = None

datastore = store.ChangeDetectionStore()
messages = []
extra_stylesheets = []

update_q = queue.Queue()


app = Flask(__name__, static_url_path='/static')
app.config['STATIC_RESOURCES'] = "/app/static"

# app.config['SECRET_KEY'] = 'secret!'

# Disables caching of the templates
app.config['TEMPLATES_AUTO_RELOAD'] = True


# We use the whole watch object from the store/JSON so we can see if there's some related status in terms of a thread
# running or something similar.
@app.template_filter('format_last_checked_time')
def _jinja2_filter_datetime(watch_obj, format="%Y-%m-%d %H:%M:%S"):
    # Worker thread tells us which UUID it is currently processing.
    for t in running_update_threads:
        if t.current_uuid == watch_obj['uuid']:
            return "Checking now.."

    if watch_obj['last_checked'] == 0:
        return 'Not yet'

    return timeago.format(int(watch_obj['last_checked']), time.time())


# @app.context_processor
# def timeago():
#    def _timeago(lower_time, now):
#        return timeago.format(lower_time, now)
#    return dict(timeago=_timeago)

@app.template_filter('format_timestamp_timeago')
def _jinja2_filter_datetimestamp(timestamp, format="%Y-%m-%d %H:%M:%S"):
    if timestamp == 0:
        return 'Not yet'
    return timeago.format(timestamp, time.time())
    # return timeago.format(timestamp, time.time())
    # return datetime.datetime.utcfromtimestamp(timestamp).strftime(format)


@app.route("/", methods=['GET'])
def main_page():
    global messages

    limit_tag = request.args.get('tag')

    # Sort by last_changed and add the uuid which is usually the key..
    sorted_watches = []
    for uuid, watch in datastore.data['watching'].items():
        if limit_tag != None:
            # Support for comma separated list of tags.
            for tag_in_watch in watch['tag'].split(','):
                tag_in_watch = tag_in_watch.strip()
                if tag_in_watch == limit_tag:
                    watch['uuid'] = uuid
                    sorted_watches.append(watch)

        else:
            watch['uuid'] = uuid
            sorted_watches.append(watch)

    sorted_watches.sort(key=lambda x: x['last_changed'], reverse=True)

    existing_tags = datastore.get_all_tags()
    output = render_template("watch-overview.html",
                             watches=sorted_watches,
                             messages=messages,
                             tags=existing_tags,
                             active_tag=limit_tag)

    # Show messages but once.
    messages = []
    return output

@app.route("/scrub", methods=['GET', 'POST'])
def scrub_page():
    from pathlib import Path

    global messages

    if request.method == 'POST':
        confirmtext = request.form.get('confirmtext')

        if confirmtext == 'scrub':

            for txt_file_path in Path('/datastore').rglob('*.txt'):
                os.unlink(txt_file_path)

            for uuid, watch in datastore.data['watching'].items():
                watch['last_checked'] = 0
                watch['last_changed'] = 0
                watch['previous_md5'] = None
                watch['history'] = {}

            datastore.needs_write = True
            messages.append({'class': 'ok', 'message': 'Cleaned all version history.'})
        else:
            messages.append({'class': 'error', 'message': 'Wrong confirm text.'})

        return redirect(url_for('main_page'))

    return render_template("scrub.html")


@app.route("/edit", methods=['GET', 'POST'])
def edit_page():
    global messages
    import validators

    if request.method == 'POST':
        uuid = request.args.get('uuid')

        url = request.form.get('url').strip()
        tag = request.form.get('tag').strip()

        form_headers = request.form.get('headers').strip().split("\n")
        extra_headers = {}
        if form_headers:
            for header in form_headers:
                if len(header):
                    parts = header.split(':', 1)
                    extra_headers.update({parts[0].strip(): parts[1].strip()})

        validators.url(url)  # @todo switch to prop/attr/observer
        datastore.data['watching'][uuid].update({'url': url,
                                                 'tag': tag,
                                                 'headers': extra_headers})
        datastore.needs_write = True

        messages.append({'class': 'ok', 'message': 'Updated watch.'})

        return redirect(url_for('main_page'))

    else:

        uuid = request.args.get('uuid')
        output = render_template("edit.html", uuid=uuid, watch=datastore.data['watching'][uuid], messages=messages)

    return output


@app.route("/settings", methods=['GET', "POST"])
def settings_page():
    global messages
    if request.method == 'POST':
        try:
            minutes = int(request.values.get('minutes').strip())
        except ValueError:
            messages.append({'class': 'error', 'message': "Invalid value given, use an integer."})

        else:
            if minutes >= 5 and minutes <= 600:
                datastore.data['settings']['requests']['minutes_between_check'] = minutes
                datastore.needs_write = True

                messages.append({'class': 'ok', 'message': "Updated"})
            else:
                messages.append({'class': 'error', 'message': "Must be equal to or greater than 5 and less than 600 minutes"})

    output = render_template("settings.html", messages=messages, minutes=datastore.data['settings']['requests']['minutes_between_check'])
    messages =[]

    return output

@app.route("/import", methods=['GET', "POST"])
def import_page():
    import validators
    global messages
    remaining_urls=[]

    good = 0

    if request.method == 'POST':
        urls = request.values.get('urls').split("\n")
        for url in urls:
            url = url.strip()
            if len(url) and validators.url(url):
                datastore.add_watch(url=url.strip(), tag="")
                good += 1
            else:
                if len(url):
                    remaining_urls.append(url)

        messages.append({'class': 'ok', 'message': "{} Imported, {} Skipped.".format(good, len(remaining_urls))})

    output = render_template("import.html",
                             messages=messages,
                             remaining="\n".join(remaining_urls)
                             )
    messages = []
    return output


@app.route("/diff/<string:uuid>", methods=['GET'])
def diff_history_page(uuid):
    global messages
    global extra_stylesheets
    extra_stylesheets.append('/static/css/diff.css')

    watch = datastore.data['watching'][uuid]

    dates = list(watch['history'].keys())
    # Convert to int, sort and back to str again
    dates = [int(i) for i in dates]
    dates.sort(reverse=True)
    dates = [str(i) for i in dates]

    newest_file = watch['history'][dates[0]]
    with open(newest_file, 'r') as f:
        newest_version_file_contents = f.read()

    previous_version = request.args.get('previous_version')

    try:
        previous_file = watch['history'][previous_version]
    except KeyError:
        # Not present, use a default value, the second one in the sorted list.
        previous_file = watch['history'][dates[1]]

    with open(previous_file, 'r') as f:
        previous_version_file_contents = f.read()

    output = render_template("diff.html", watch_a=watch,
                             messages=messages,
                             newest=newest_version_file_contents,
                             previous=previous_version_file_contents,
                             extra_stylesheets=extra_stylesheets,
                             versions=dates[1:],
                             newest_version_timestamp=dates[0],
                             current_previous_version=str(previous_version),
                             current_diff_url=watch['url'])

    return output

@app.route("/favicon.ico", methods=['GET'])
def favicon():
    return send_from_directory("/app/static/images", filename="favicon.ico")


# We're good but backups are even better!
@app.route("/backup", methods=['GET'])
def get_backup():
    import zipfile
    from pathlib import Path
    import zlib

    # create a ZipFile object
    backupname = "changedetection-backup-{}.zip".format(int(time.time()))

    # We only care about UUIDS from the current index file
    uuids = list(datastore.data['watching'].keys())

    with zipfile.ZipFile(os.path.join("/datastore", backupname), 'w', compression=zipfile.ZIP_DEFLATED,
                         compresslevel=6) as zipObj:

        # Be sure we're written fresh
        datastore.sync_to_json()

        # Add the index
        zipObj.write(os.path.join("/datastore", "url-watches.json"))
        # Add any snapshot data we find
        for txt_file_path in Path('/datastore').rglob('*.txt'):
            parent_p = txt_file_path.parent
            if parent_p.name in uuids:
                zipObj.write(txt_file_path)

    return send_file(os.path.join("/datastore", backupname),
                     as_attachment=True,
                     mimetype="application/zip",
                     attachment_filename=backupname)



# A few self sanity checks, mostly for developer/bug check
@app.route("/self-check", methods=['GET'])
def selfcheck():
    output = "All fine"
    # In earlier versions before a single threaded write of the JSON store, sometimes histories could get mixed.
    # Could also maybe affect people who manually fiddle with their JSON store?
    for uuid, watch in datastore.data['watching'].items():
        for timestamp, path in watch['history'].items():
            # Each history snapshot should include a full path, which contains the {uuid}
            if not uuid in path:
                output = "Something weird in {}, suspected incorrect snapshot path.".format(uuid)

    return output

@app.route("/static/<string:group>/<string:filename>", methods=['GET'])
def static_content(group, filename):
    try:
        return send_from_directory("/app/static/{}".format(group), filename=filename)
    except FileNotFoundError:
        abort(404)


@app.route("/api/add", methods=['POST'])
def api_watch_add():
    global messages

    # @todo add_watch should throw a custom Exception for validation etc
    new_uuid = datastore.add_watch(url=request.form.get('url').strip(), tag=request.form.get('tag').strip())
    # Straight into the queue.
    update_q.put(new_uuid)

    messages.append({'class': 'ok', 'message': 'Watch added.'})
    return redirect(url_for('main_page'))


@app.route("/api/delete", methods=['GET'])
def api_delete():
    global messages
    uuid = request.args.get('uuid')
    datastore.delete(uuid)
    messages.append({'class': 'ok', 'message': 'Deleted.'})

    return redirect(url_for('main_page'))


@app.route("/api/checknow", methods=['GET'])
def api_watch_checknow():
    global messages

    tag = request.args.get('tag')
    uuid = request.args.get('uuid')
    i=0

    if uuid:
        update_q.put(uuid)
        i = 1

    elif tag != None:
        for watch_uuid, watch in datastore.data['watching'].items():
            if (tag != None and tag in watch['tag']):
                i += 1
                update_q.put(watch_uuid)
    else:
        # No tag, no uuid, add everything.
        for watch_uuid, watch in datastore.data['watching'].items():
            i += 1
            update_q.put(watch_uuid)

    messages.append({'class': 'ok', 'message': "{} watches are rechecking.".format(i)})
    return redirect(url_for('main_page', tag=tag))



# Requests for checking on the site use a pool of thread Workers managed by a Queue.
class Worker(threading.Thread):

    current_uuid = None

    def __init__(self, q, *args, **kwargs):
        self.q = q
        super().__init__(*args, **kwargs)

    def run(self):
        try:
            while True:
                uuid = self.q.get()  # Blocking
                self.current_uuid = uuid
                # A little safety protection
                if uuid in list( datastore.data['watching'].keys()):
                    fetch_site_status.perform_site_check(uuid=uuid, datastore=datastore)
                self.current_uuid = None # Done
                self.q.task_done()

        except KeyboardInterrupt:
            return

# Thread runner to check every minute, look for new watches to feed into the Queue.
def ticker_thread_check_time_launch_checks():

    # Spin up Workers.
    for _ in range(datastore.data['settings']['requests']['workers']):
        new_worker = Worker(update_q)
        running_update_threads.append(new_worker)
        new_worker.start()

    # Every minute check for new UUIDs to follow up on
    while True:
        minutes = datastore.data['settings']['requests']['minutes_between_check']
        for uuid, watch in datastore.data['watching'].items():
            if watch['last_checked'] <= time.time() - (minutes * 60):
                update_q.put(uuid)

        time.sleep(60)


# Thread runner, this helps with thread/write issues when there are many operations that want to update the JSON
# by just running periodically in one thread, according to python, dict updates are threadsafe.
def save_datastore():
    try:
        while True:
            if datastore.needs_write:
                datastore.sync_to_json()
            time.sleep(5)

    except KeyboardInterrupt:
        return

def main(argv):
    ssl_mode = False
    port = 5000

    try:
        opts, args = getopt.getopt(argv, "sp:", "purge")
    except getopt.GetoptError:
        print('backend.py -s SSL enable -p [port]')
        sys.exit(2)

    for opt, arg in opts:
        if opt == '--purge':
            # Remove history, the actual files you need to delete manually.
            for uuid, watch in datastore.data['watching'].items():
                watch.update({'history': {}, 'last_checked': 0, 'last_changed': 0, 'previous_md5': None})

        if opt == '-s':
            ssl_mode = True

        if opt == '-p':
            port = arg

    # @todo handle ctrl break
    ticker_thread = threading.Thread(target=ticker_thread_check_time_launch_checks).start()

    save_data_thread = threading.Thread(target=save_datastore).start()

    # @todo finalise SSL config, but this should get you in the right direction if you need it.
    if ssl_mode:
        eventlet.wsgi.server(eventlet.wrap_ssl(eventlet.listen(('', port)),
                                               certfile='cert.pem',
                                               keyfile='privkey.pem',
                                               server_side=True), app)

    else:
        eventlet.wsgi.server(eventlet.listen(('', port)), app)


if __name__ == '__main__':
    main(sys.argv[1:])