#!/usr/bin/env python


__license__ = 'GPL v3'
__copyright__ = '2015, Kovid Goyal <kovid at kovidgoyal.net>'

import inspect
import json as jsonlib
import numbers
import re
import sys
import textwrap
import time
from operator import attrgetter

from calibre.srv.errors import HTTPNotFound, HTTPSimpleResponse, RouteError
from calibre.srv.utils import http_date
from calibre.utils.serialize import MSGPACK_MIME, json_dumps, msgpack_dumps
from polyglot import http_client
from polyglot.builtins import iteritems, itervalues
from polyglot.urllib import quote as urlquote

default_methods = frozenset(('HEAD', 'GET'))


def json(ctx, rd, endpoint, output):
    rd.outheaders.set('Content-Type', 'application/json; charset=UTF-8', replace_all=True)
    if isinstance(output, bytes) or hasattr(output, 'fileno'):
        ans = output  # Assume output is already UTF-8 encoded json
    else:
        ans = json_dumps(output)
    return ans


def msgpack(ctx, rd, endpoint, output):
    rd.outheaders.set('Content-Type', MSGPACK_MIME, replace_all=True)
    if isinstance(output, bytes) or hasattr(output, 'fileno'):
        ans = output  # Assume output is already msgpack encoded
    else:
        ans = msgpack_dumps(output)
    return ans


def msgpack_or_json(ctx, rd, endpoint, output):
    accept = rd.inheaders.get('Accept', all=True)
    func = msgpack if MSGPACK_MIME in accept else json
    return func(ctx, rd, endpoint, output)


json.loads, json.dumps = jsonlib.loads, jsonlib.dumps


def route_key(route):
    return route.partition('{')[0].rstrip('/')


def endpoint(route,
             methods=default_methods,
             types=None,
             auth_required=True,
             android_workaround=False,

             # Manage the HTTP caching
             # Set to None or 'no-cache' to prevent caching of this endpoint
             # Set to a number to cache for at most number hours
             # Set to a tuple (cache_type, max_age) to explicitly set the
             # Cache-Control header
             cache_control=False,

             # The HTTP code to be used when no error occurs. By default it is
             # 200 for GET and HEAD and 201 for POST
             ok_code=None,

             postprocess=None,

             # Needs write access to the calibre database
             needs_db_write=False

):
    from calibre.srv.handler import Context
    from calibre.srv.http_response import RequestData

    def annotate(f):
        f.route = route.rstrip('/') or '/'
        f.route_key = route_key(f.route)
        f.types = types or {}
        f.methods = methods
        f.auth_required = auth_required
        f.android_workaround = android_workaround
        f.cache_control = cache_control
        f.postprocess = postprocess
        f.ok_code = ok_code
        f.is_endpoint = True
        f.needs_db_write = needs_db_write
        argspec = inspect.getfullargspec(f)
        if len(argspec.args) < 2:
            raise TypeError(f'The endpoint {f.route!r} must take at least two arguments')
        f.__annotations__ = {
            argspec.args[0]: Context,
            argspec.args[1]: RequestData,
        }
        f.__doc__ = textwrap.dedent(f.__doc__ or '') + '\n\n' + (
            (f':type {argspec.args[0]}: calibre.srv.handler.Context\n') +
            (f':type {argspec.args[1]}: calibre.srv.http_response.RequestData\n')
        )
        return f
    return annotate


class Route:

    var_pat = None

    def __init__(self, endpoint_):
        if self.var_pat is None:
            Route.var_pat = self.var_pat = re.compile(r'{(.+?)}')
        self.endpoint = endpoint_
        del endpoint_
        if not self.endpoint.route.startswith('/'):
            raise RouteError(f'A route must start with /, {self.endpoint.route} does not')
        parts = list(filter(None, self.endpoint.route.split('/')))
        matchers = self.matchers = []
        self.defaults = {}
        found_optional_part = False
        self.soak_up_extra = False
        self.type_checkers = self.endpoint.types.copy()

        def route_error(msg):
            return RouteError(f'{self.endpoint.route} is not valid: {msg}')

        for i, p in enumerate(parts):
            if p[0] == '{':
                if p[-1] != '}':
                    raise route_error('Invalid route, variable components must be in a {}')
                name = p[1:-1]
                is_sponge = name.startswith('+')
                if is_sponge:
                    if p is not parts[-1]:
                        raise route_error('Can only specify + in the last component')
                    name = name[1:]

                if '=' in name:
                    found_optional_part = i
                    name, default = name.partition('=')[::2]
                    if '{' in default or '}' in default:
                        raise route_error('The characters {} are not allowed in default values')
                    default = self.defaults[name] = eval(default)
                    if isinstance(default, numbers.Number):
                        self.type_checkers[name] = type(default)
                    if is_sponge and not isinstance(default, str):
                        raise route_error('Soak up path component must have a default value of string type')
                else:
                    if found_optional_part is not False:
                        raise route_error('Cannot have non-optional path components after optional ones')
                if is_sponge:
                    self.soak_up_extra = name
                matchers.append((name, True))
            else:
                if found_optional_part is not False:
                    raise route_error('Cannot have non-optional path components after optional ones')
                matchers.append((None, p.__eq__))
        self.names = [n for n, m in matchers if n is not None]
        self.all_names = frozenset(self.names)
        self.required_names = self.all_names - frozenset(self.defaults)
        argspec = inspect.getfullargspec(self.endpoint)
        if len(self.names) + 2 != len(argspec.args) - len(argspec.defaults or ()):
            raise route_error(f'Function must take {len(self.names) + 2} non-default arguments')
        if argspec.args[2:len(self.names)+2] != self.names:
            raise route_error("Function's argument names do not match the variable names in the route")
        if not frozenset(self.type_checkers).issubset(frozenset(self.names)):
            raise route_error(f'There exist type checkers that do not correspond to route variables: {set(self.type_checkers)-set(self.names)!r}')
        self.min_size = found_optional_part if found_optional_part is not False else len(matchers)
        self.max_size = sys.maxsize if self.soak_up_extra else len(matchers)

    def matches(self, path):
        args_map = self.defaults.copy()
        num = 0
        for component, (name, matched) in zip(path, self.matchers):
            num += 1
            if matched is True:
                args_map[name] = component
            elif not matched(component):
                return False
        if self.soak_up_extra and num < len(path):
            args_map[self.soak_up_extra] += '/' + '/'.join(path[num:])
            num = len(path)
        if num < len(path):
            return False

        def check(tc, val):
            try:
                return tc(val)
            except Exception:
                raise HTTPNotFound('Argument of incorrect type')
        for name, tc in iteritems(self.type_checkers):
            args_map[name] = check(tc, args_map[name])
        return (args_map[name] for name in self.names)

    def url_for(self, **kwargs):
        names = frozenset(kwargs)
        not_spec = self.required_names - names
        if not_spec:
            raise RouteError('The required variable(s) {} were not specified for the route: {}'.format(','.join(not_spec), self.endpoint.route))
        unknown = names - self.all_names
        if unknown:
            raise RouteError('The variable(s) {} are not part of the route: {}'.format(','.join(unknown), self.endpoint.route))

        def quoted(x):
            if not isinstance(x, (str, bytes)):
                x = str(x)
            if isinstance(x, str):
                x = x.encode('utf-8')
            return urlquote(x, '')
        args = {k:'' for k in self.defaults}
        args.update(kwargs)
        args = {k:quoted(v) for k, v in iteritems(args)}
        route = self.var_pat.sub(lambda m:'{{{}}}'.format(m.group(1).partition('=')[0].lstrip('+')), self.endpoint.route)
        return route.format(**args).rstrip('/')

    def __str__(self):
        return self.endpoint.route
    __unicode__ = __repr__ = __str__


class Router:

    def __init__(self, endpoints=None, ctx=None, url_prefix=None, auth_controller=None):
        self.routes = {}
        self.url_prefix = (url_prefix or '').rstrip('/')
        self.strip_path = None
        if self.url_prefix:
            if not self.url_prefix.startswith('/'):
                self.url_prefix = '/' + self.url_prefix
            self.strip_path = tuple(self.url_prefix[1:].split('/'))
        self.ctx = ctx
        self.auth_controller = auth_controller
        self.init_session = getattr(ctx, 'init_session', lambda ep, data:None)
        self.finalize_session = getattr(ctx, 'finalize_session', lambda ep, data, output:None)
        self.endpoints = set()
        if endpoints is not None:
            self.load_routes(endpoints)
            self.finalize()

    def add(self, endpoint):
        if endpoint in self.endpoints:
            return
        key = endpoint.route_key
        if key in self.routes:
            raise RouteError(f'A route with the key: {key} already exists as: {self.routes[key]}')
        self.routes[key] = Route(endpoint)
        self.endpoints.add(endpoint)

    def load_routes(self, items):
        for item in items:
            if getattr(item, 'is_endpoint', False) is True:
                self.add(item)

    def __iter__(self):
        return itervalues(self.routes)

    def finalize(self):
        try:
            lsz = max(len(r.matchers) for r in self)
        except ValueError:
            lsz = 0
        self.min_size_map = {sz:frozenset(r for r in self if r.min_size <= sz) for sz in range(lsz + 1)}
        self.max_size_map = {sz:frozenset(r for r in self if r.max_size >= sz) for sz in range(lsz + 1)}
        self.soak_routes = sorted(frozenset(r for r in self if r.soak_up_extra), key=attrgetter('min_size'), reverse=True)

    def find_route(self, path):
        if self.strip_path is not None and path[:len(self.strip_path)] == self.strip_path:
            path = path[len(self.strip_path):]
        size = len(path)
        # routes for which min_size <= size <= max_size
        routes = self.max_size_map.get(size, set()) & self.min_size_map.get(size, set())
        for route in sorted(routes, key=attrgetter('max_size'), reverse=True):
            args = route.matches(path)
            if args is not False:
                return route.endpoint, args
        for route in self.soak_routes:
            if route.min_size <= size:
                args = route.matches(path)
                if args is not False:
                    return route.endpoint, args
        raise HTTPNotFound()

    def read_cookies(self, data):
        data.cookies = c = {}

        for cval in data.inheaders.get('Cookie', all=True):
            if isinstance(cval, bytes):
                cval = cval.decode('utf-8', 'replace')
            for x in cval.split(';'):
                x = x.strip()
                if x:
                    k, v = x.partition('=')[::2]
                    if k:
                        # Since we only set simple hex encoded cookies, we dont
                        # need more sophisticated value parsing
                        c[k] = v.strip('"')

    def dispatch(self, data):
        endpoint_, args = self.find_route(data.path)
        if data.method not in endpoint_.methods:
            raise HTTPSimpleResponse(http_client.METHOD_NOT_ALLOWED)

        self.read_cookies(data)

        if endpoint_.auth_required and self.auth_controller is not None:
            self.auth_controller(data, endpoint_)

        if endpoint_.ok_code is not None:
            data.status_code = endpoint_.ok_code

        self.init_session(endpoint_, data)
        if endpoint_.needs_db_write:
            self.ctx.check_for_write_access(data)
        ans = endpoint_(self.ctx, data, *args)
        self.finalize_session(endpoint_, data, ans)
        outheaders = data.outheaders

        pp = endpoint_.postprocess
        if pp is not None:
            ans = pp(self.ctx, data, endpoint_, ans)

        cc = endpoint_.cache_control
        if cc is not False and 'Cache-Control' not in data.outheaders:
            if cc is None or cc == 'no-cache':
                outheaders['Expires'] = http_date(10000.0)  # A date in the past
                outheaders['Cache-Control'] = 'no-cache, must-revalidate'
                outheaders['Pragma'] = 'no-cache'
            elif isinstance(cc, numbers.Number):
                cc = int(60 * 60 * cc)
                outheaders['Cache-Control'] = f'public, max-age={cc}'
                if cc == 0:
                    cc -= 100000
                outheaders['Expires'] = http_date(cc + time.time())
            else:
                ctype, max_age = cc
                max_age = int(60 * 60 * max_age)
                outheaders['Cache-Control'] = f'{ctype}, max-age={max_age}'
                if max_age == 0:
                    max_age -= 100000
                outheaders['Expires'] = http_date(max_age + time.time())
        return ans

    def url_for(self, route, **kwargs):
        if route is None:
            return self.url_prefix or '/'
        route = getattr(route, 'route_key', route)
        return self.url_prefix + self.routes[route].url_for(**kwargs)
