# -*- coding: utf-8 -*-


from contextlib import contextmanager
import inspect
import sys
import json
import datetime

import tornado.ioloop
import tornado.web
import tornado.gen
import tornado.concurrent
from concurrent.futures import ThreadPoolExecutor
from tornado.concurrent import run_on_executor


import logging
logger = logging.getLogger(__name__)


MAX_WORKERS = 4

def json_response(data=None, status=200, text='ok'):
    if not data:
        data = {}
    return {'status': {'code': status, 'text': text}, 'data': data}

def _to_json(python_object):
    if isinstance(python_object, datetime.datetime):
        if python_object.year < 1900:
            tt = python_object.timetuple()
            return '%d-%02d-%02dT%02d:%02d%02dZ' % tuple(list(tt)[:6])
        return python_object.strftime('%Y-%m-%dT%H:%M:%SZ')
    raise TypeError('%s %s is not JSON serializable' % (repr(python_object), type(python_object)))

def json_dumps(obj):
    indent = 2
    return json.dumps(obj, indent=indent, default=_to_json, ensure_ascii=False).encode()

def trim(docstring):
    if not docstring:
        return ''
    # Convert tabs to spaces (following the normal Python rules)
    # and split into a list of lines:
    lines = docstring.expandtabs().splitlines()
    # Determine minimum indentation (first line doesn't count):
    indent = sys.maxsize
    for line in lines[1:]:
        stripped = line.lstrip()
        if stripped:
            indent = min(indent, len(line) - len(stripped))
    # Remove indentation (first line is special):
    trimmed = [lines[0].strip()]
    if indent < sys.maxsize:
        for line in lines[1:]:
            trimmed.append(line[indent:].rstrip())
    # Strip off trailing and leading blank lines:
    while trimmed and not trimmed[-1]:
        trimmed.pop()
    while trimmed and not trimmed[0]:
        trimmed.pop(0)
    # Return a single string:
    return '\n'.join(trimmed)

@contextmanager
def defaultcontext():
    yield

class ApiHandler(tornado.web.RequestHandler):
    executor = ThreadPoolExecutor(max_workers=MAX_WORKERS)

    def initialize(self, context=None, public=False):
        self._context = context
        self._public = public

    def get(self):
        self.write('use POST')

    @run_on_executor
    def api_task(self, request):
        import settings
        context = self._context
        if context is None:
            context = defaultcontext
        action = None
        if request.headers.get('Content-Type') == 'application/json':
            try:
                r = json.loads(request.body.decode())
                action = r['action']
                data = r['data']
            except:
                action = None
        if not action:
            action = request.arguments.get('action', [None])[0].decode('utf-8')
            data = request.arguments.get('data', [b'{}'])[0]
            data = json.loads(data.decode('utf-8')) if data else {}
        if not action:
            methods = list(actions.keys())
            api = []
            for f in sorted(methods):
                api.append({'name': f,
                            'doc': actions.doc(f).replace('\n', '<br>\n')})
            response = json_response(api)
        else:
            if settings.DEBUG_API:
                logger.debug('API %s %s', action, data)
            if self._public:
                f = actions.versions['public'].get(action)
            else:
                f = actions.get(action)
            if f:
                with context():
                    try:
                        response = f(data)
                    except:
                        logger.debug('FAILED %s %s', action, data, exc_info=True)
                        response = json_response(status=500, text='%s failed' % action)
            else:
                response = json_response(status=400, text='Unknown action %s' % action)
        return response

    @tornado.gen.coroutine
    def post(self):
        if 'origin' in self.request.headers and self.request.host not in self.request.headers['origin']:
            logger.debug('reject cross site attempt to access api %s', self.request)
            self.set_status(403)
            self.write('')
            return

        response = yield self.api_task(self.request)
        if not 'status' in response:
            response = json_response(response)
        response = json_dumps(response)
        self.set_header('Content-Type', 'application/json')
        self.write(response)

class ApiActions(dict):
    properties = {}
    versions = {}

    def _api(self, data, version=None):
        '''
            returns list of all known api actions
            takes {
                docs: bool
            }
            if docs is true, action properties contain docstrings
            returns {
                actions: {
                    'api': {
                        cache: true,
                        doc: 'recursion'
                    },
                    'hello': {
                        cache: true,
                        ..
                    }
                    ...
                }
            }
        '''
        data = data or {}
        docs = data.get('docs', False)
        code = data.get('code', False)
        if version:
            _actions = list(self.versions[version].keys())
        else:
            _actions = list(self.keys())
        _actions.sort()
        actions = {}
        for a in _actions:
            actions[a] = self.properties[a]
            if docs:
                actions[a]['doc'] = self.doc(a, version)
            if code:
                actions[a]['code'] = self.code(a, version)
        return {'actions': actions}

    def __init__(self):
        self.register(self._api, 'api')

    def doc(self, name, version=None):
        if version:
            f = self.versions[version][name]
        else:
            f = self[name]
        return trim(f.__doc__)

    def code(self, name, version=None):
        if version:
            f = self.versions[version][name]
        else:
            f = self[name]
        if name != 'api' and hasattr(f, 'func_closure') and f.__closure__:
            fc = [c for c in f.__closure__ if hasattr(c.cell_contents, '__call__')]
            f = fc[len(fc)-1].cell_contents 
        info = f.__code__.co_filename
        info = '%s:%s' % (info, f.__code__.co_firstlineno)
        return info, trim(inspect.getsource(f))

    def register(self, method, action=None, cache=True, version=None):
        if not action:
            action = method.__name__
        if version:
            if version not in self.versions:
                self.versions[version] = {}
                self.register(lambda data: self._api(data, version), action='api', version=version)
            self.versions[version][action] = method
        else:
            self[action] = method
        self.properties[action] = {'cache': cache}

    def unregister(self, action):
        if action in self:
            del self[action]


actions = ApiActions()