#!/usr/bin/env python

# Copyright 2018 Red Hat, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import functools
import urllib
from collections import defaultdict

import datetime

import github3.exceptions
import re
import time

import graphene
from requests import HTTPError
from requests.structures import CaseInsensitiveDict

from tests.fake_graphql import FakeGithubQuery
from zuul.driver.github.githubconnection import utc

FAKE_BASE_URL = 'https://example.com/api/v3/'


class FakeUser(object):
    def __init__(self, login):
        self.login = login
        self.name = login
        self.email = '%s@example.com' % login
        self.html_url = 'https://example.com/%s' % login


class FakeBranch(object):
    def __init__(self, fake_repo, branch='master', protected=False):
        self.name = branch
        self._fake_repo = fake_repo

    @property
    def protected(self):
        return self.name in self._fake_repo._branch_protection_rules

    def as_dict(self):
        return {
            'name': self.name,
            'protected': self.protected
        }


class FakeCreator:
    def __init__(self, login):
        self.login = login


class FakeStatus(object):
    def __init__(self, state, url, description, context, user):
        self.state = state
        self.context = context
        self.creator = FakeCreator(user)
        self._url = url
        self._description = description

    def as_dict(self):
        return {
            'state': self.state,
            'url': self._url,
            'description': self._description,
            'context': self.context,
            'creator': {
                'login': self.creator.login
            }
        }


class FakeApp:
    def __init__(self, name, slug):
        self.name = name
        self.slug = slug


class FakeCheckRun(object):
    def __init__(self, id, name, details_url, output, status, conclusion,
                 completed_at, external_id, actions, app):
        if actions is None:
            actions = []

        self.id = id
        self.name = name
        self.details_url = details_url
        self.output = output
        self.conclusion = conclusion
        self.completed_at = completed_at
        self.external_id = external_id
        self.actions = actions
        self.app = FakeApp(name=app, slug=app)

        # Github automatically sets the status to "completed" if a conclusion
        # is provided.
        if conclusion is not None:
            self.status = "completed"
        else:
            self.status = status

    def as_dict(self):
        return {
            'id': self.id,
            "name": self.name,
            "status": self.status,
            "output": self.output,
            "details_url": self.details_url,
            "conclusion": self.conclusion,
            "completed_at": self.completed_at,
            "external_id": self.external_id,
            "actions": self.actions,
            "app": {
                "slug": self.app.slug,
                "name": self.app.name,
            },
        }

    def update(self, conclusion, completed_at, output, details_url,
               external_id, actions):
        self.conclusion = conclusion
        self.completed_at = completed_at
        self.output = output
        self.details_url = details_url
        self.external_id = external_id
        self.actions = actions

        # As we are only calling the update method when a build is completed,
        # we can always set the status to "completed".
        self.status = "completed"


class FakeGHReview(object):

    def __init__(self, data):
        self.data = data

    def as_dict(self):
        return self.data


class FakeCombinedStatus(object):
    def __init__(self, sha, statuses):
        self.sha = sha
        self.statuses = statuses


class FakeCommit(object):
    def __init__(self, sha):
        self._statuses = []
        self.sha = sha
        self._check_runs = []

    def set_status(self, state, url, description, context, user):
        status = FakeStatus(
            state, url, description, context, user)
        # always insert a status to the front of the list, to represent
        # the last status provided for a commit.
        self._statuses.insert(0, status)

    def set_check_run(self, id, name, details_url, output, status, conclusion,
                      completed_at, external_id, actions, app):
        check_run = FakeCheckRun(
            id,
            name,
            details_url,
            output,
            status,
            conclusion,
            completed_at,
            external_id,
            actions,
            app,
        )
        # Always insert a check_run to the front of the list to represent the
        # last check_run provided for a commit.
        self._check_runs.insert(0, check_run)
        return check_run

    def get_url(self, path, params=None):
        if path == 'statuses':
            statuses = [s.as_dict() for s in self._statuses]
            return FakeResponse(statuses)
        if path == "check-runs":
            check_runs = [c.as_dict() for c in self._check_runs]
            resp = {"total_count": len(check_runs), "check_runs": check_runs}
            return FakeResponse(resp)

    def statuses(self):
        return self._statuses

    def check_runs(self):
        return self._check_runs

    def status(self):
        '''
        Returns the combined status wich only contains the latest statuses of
        the commit together with some other information that we don't need
        here.
        '''
        latest_statuses_by_context = {}
        for status in self._statuses:
            if status.context not in latest_statuses_by_context:
                latest_statuses_by_context[status.context] = status
        combined_statuses = latest_statuses_by_context.values()
        return FakeCombinedStatus(self.sha, combined_statuses)


class FakeRepository(object):
    def __init__(self, name, data):
        self._api = FAKE_BASE_URL
        self._branches = [FakeBranch(self)]
        self._commits = {}
        self.data = data
        self.name = name
        self.check_run_counter = 0

        # Simple dictionary to store permission values per feature (e.g.
        # checks, Repository contents, Pull requests, Commit statuses, ...).
        # Could be used to just enable/deable a permission (True, False) or
        # provide more specific values like "read" or "read&write". The mocked
        # functionality in the FakeRepository class should then check for this
        # value and raise an appropriate exception like a production Github
        # would do in case the permission is not sufficient or missing at all.
        self._permissions = {}

        # List of branch protection rules
        self._branch_protection_rules = defaultdict(FakeBranchProtectionRule)
        self._repodata = {
            'allow_merge_commit': True,
            'allow_squash_merge': True,
            'allow_rebase_merge': True,
        }

        # fail the next commit requests with 404
        self.fail_not_found = 0

    def branches(self, protected=False):
        if protected:
            # simulate there is no protected branch
            return [b for b in self._branches if b.protected]
        return self._branches

    def _set_branch_protection(self, branch_name, protected=True,
                               contexts=None, require_review=False):
        if not protected:
            if branch_name in self._branch_protection_rules:
                del self._branch_protection_rules[branch_name]
            return

        rule = self._branch_protection_rules[branch_name]
        rule.pattern = branch_name
        rule.required_contexts = contexts or []
        rule.require_reviews = require_review

    def _set_permission(self, key, value):
        # NOTE (felix): Currently, this is only used to mock a repo with
        # missing checks API permissions. But we could also use it to test
        # arbitrary permission values like missing write, but only read
        # permissions for a specific functionality.
        self._permissions[key] = value

    def _build_url(self, *args, **kwargs):
        path_args = ['repos', self.name]
        path_args.extend(args)
        fakepath = '/'.join(path_args)
        return FAKE_BASE_URL + fakepath

    def _get(self, url, headers=None):
        client = FakeGithubClient(data=self.data)
        return client.session.get(url, headers)

    def _create_branch(self, branch):
        self._branches.append((FakeBranch(self, branch=branch)))

    def _delete_branch(self, branch_name):
        self._branches = [b for b in self._branches if b.name != branch_name]

    def create_status(self, sha, state, url, description, context,
                      user='zuul'):
        # Since we're bypassing github API, which would require a user, we
        # default the user as 'zuul' here.
        commit = self._commits.get(sha, None)
        if commit is None:
            commit = FakeCommit(sha)
            self._commits[sha] = commit
        commit.set_status(state, url, description, context, user)

    def create_check_run(self, head_sha, name, details_url=None, output=None,
                         status=None, conclusion=None, completed_at=None,
                         external_id=None, actions=None, app="zuul"):

        # Raise the appropriate github3 exception in case we don't have
        # permission to access the checks API
        if self._permissions.get("checks") is False:
            # To create a proper github3 exception, we need to mock a response
            # object
            raise github3.exceptions.ForbiddenError(
                FakeResponse("Resource not accessible by integration", 403)
            )

        commit = self._commits.get(head_sha, None)
        if commit is None:
            commit = FakeCommit(head_sha)
            self._commits[head_sha] = commit
        self.check_run_counter += 1
        commit.set_check_run(
            str(self.check_run_counter),
            name,
            details_url,
            output,
            status,
            conclusion,
            completed_at,
            external_id,
            actions,
            app,
        )

    def commit(self, sha):

        if self.fail_not_found > 0:
            self.fail_not_found -= 1
            resp = FakeResponse(404, 'Not found')
            raise github3.exceptions.NotFoundError(resp)

        commit = self._commits.get(sha, None)
        if commit is None:
            commit = FakeCommit(sha)
            self._commits[sha] = commit
        return commit

    def get_url(self, path, params=None):
        if '/' in path:
            entity, request = path.split('/', 1)
        else:
            entity = path
            request = None

        if entity == 'branches':
            return self.get_url_branches(request, params=params)
        if entity == 'collaborators':
            return self.get_url_collaborators(request)
        if entity == 'commits':
            return self.get_url_commits(request, params=params)
        if entity == '':
            return self.get_url_repo()
        else:
            return None

    def get_url_branches(self, path, params=None):
        if path is None:
            # request wants a branch list
            return self.get_url_branch_list(params)

        elements = path.split('/')

        entity = elements[-1]
        if entity == 'protection':
            branch = '/'.join(elements[0:-1])
            return self.get_url_protection(branch)
        else:
            # fall back to treat all elements as branch
            branch = '/'.join(elements)
            return self.get_url_branch(branch)

    def get_url_commits(self, path, params=None):
        if '/' in path:
            sha, request = path.split('/', 1)
        else:
            sha = path
            request = None
        commit = self._commits.get(sha)

        # Commits are created lazy so check if there is a PR with the correct
        # head sha.
        if commit is None:
            pull_requests = [pr for pr in self.data.pull_requests.values()
                             if pr.head_sha == sha]
            if pull_requests:
                commit = FakeCommit(sha)
                self._commits[sha] = commit

        if not commit:
            return FakeResponse({}, 404)

        return commit.get_url(request, params=params)

    def get_url_branch_list(self, params):
        if params.get('protected') == 1:
            exclude_unprotected = True
        else:
            exclude_unprotected = False
        branches = [x.as_dict() for x in self.branches(exclude_unprotected)]

        return FakeResponse(branches, 200)

    def get_url_branch(self, branch_name):
        for branch in self._branches:
            if branch.name == branch_name:
                return FakeResponse(branch.as_dict())
        return FakeResponse(None, 404)

    def get_url_collaborators(self, path):
        login, entity = path.split('/')

        if entity == 'permission':
            owner, proj = self.name.split('/')
            permission = None
            for pr in self.data.pull_requests.values():
                pr_owner, pr_project = pr.project.split('/')
                if (pr_owner == owner and proj == pr_project):
                    if login in pr.admins:
                        permission = 'admin'
                        break
                    elif login in pr.writers:
                        permission = 'write'
                        break
                    else:
                        permission = 'read'
            data = {
                'permission': permission,
            }
            return FakeResponse(data)
        else:
            return None

    def get_url_protection(self, branch):
        rule = self._branch_protection_rules.get(branch)

        if not rule:
            # Note that GitHub returns 404 if branch protection is off so do
            # the same here as well
            return FakeResponse({}, 404)
        data = {
            'required_status_checks': {
                'contexts': rule.required_contexts
            }
        }
        return FakeResponse(data)

    def get_url_repo(self):
        return FakeResponse(self._repodata)

    def pull_requests(self, state=None, sort=None, direction=None):
        # sort and direction are unused currently, but present to match
        # real world call signatures.
        pulls = []
        for pull in self.data.pull_requests.values():
            if pull.project != self.name:
                continue
            if state and pull.state != state:
                continue
            pulls.append(FakePull(pull))
        return pulls


class FakeIssue(object):
    def __init__(self, fake_pull_request):
        self._fake_pull_request = fake_pull_request

    def pull_request(self):
        return FakePull(self._fake_pull_request)

    @property
    def number(self):
        return self._fake_pull_request.number


@functools.total_ordering
class FakeFile(object):
    def __init__(self, filename, previous_filename=None):
        self.filename = filename
        if previous_filename is not None:
            self.previous_filename = previous_filename

    def __eq__(self, other):
        return self.filename == other.filename

    def __lt__(self, other):
        return self.filename < other.filename

    __hash__ = object.__hash__


class FakePull(object):
    def __init__(self, fake_pull_request):
        self._fake_pull_request = fake_pull_request

    def issue(self):
        return FakeIssue(self._fake_pull_request)

    def files(self):
        # Github lists max. 300 files of a PR in alphabetical order
        return sorted(self._fake_pull_request.files)[:300]

    def reviews(self):
        return self._fake_pull_request.reviews

    def create_review(self, body, commit_id, event):
        review = FakeGHReview({
            'state': event,
            'user': {
                'login': 'fakezuul',
                'email': 'fakezuul@fake.test',
            },
            'submitted_at': time.gmtime(),
        })
        self._fake_pull_request.reviews.append(review)
        return review

    @property
    def head(self):
        client = FakeGithubClient(
            data=self._fake_pull_request.github.github_data)
        repo = client.repo_from_project(self._fake_pull_request.project)
        return repo.commit(self._fake_pull_request.head_sha)

    def commits(self):
        # since we don't know all commits of a pr we just return here a list
        # with the head_sha as the only commit
        return [self.head]

    def as_dict(self):
        pr = self._fake_pull_request
        connection = pr.github
        data = {
            'number': pr.number,
            'title': pr.subject,
            'url': 'https://%s/api/v3/%s/pulls/%s' % (
                connection.server, pr.project, pr.number
            ),
            'html_url': 'https://%s/%s/pull/%s' % (
                connection.server, pr.project, pr.number
            ),
            'updated_at': pr.updated_at,
            'base': {
                'repo': {
                    'full_name': pr.project
                },
                'ref': pr.branch,
                'sha': pr.base_sha,
            },
            'user': {
                'login': 'octocat'
            },
            'draft': pr.draft,
            'mergeable': pr.mergeable,
            'state': pr.state,
            'head': {
                'sha': pr.head_sha,
                'ref': pr.getPRReference(),
                'repo': {
                    'full_name': pr.project
                }
            },
            'merged': pr.is_merged,
            'body': pr.body,
            'body_text': pr.body_text,
            'changed_files': len(pr.files),
            'labels': [{'name': l} for l in pr.labels]
        }
        return data


class FakeIssueSearchResult(object):
    def __init__(self, issue):
        self.issue = issue


class FakeResponse(object):
    def __init__(self, data, status_code=200, status_message='OK'):
        self.status_code = status_code
        self.status_message = status_message
        self.data = data
        self.links = {}

    @property
    def content(self):
        # Building github3 exceptions requires a Response object with the
        # content attribute set.
        return self.data

    def json(self):
        return self.data

    def raise_for_status(self):
        if 400 <= self.status_code < 600:
            if isinstance(self.data, str):
                text = '{} {}'.format(self.status_code, self.data)
            else:
                text = '{} {}'.format(self.status_code, self.status_message)
            raise HTTPError(text, response=self)


class FakeGithubSession(object):

    def __init__(self, client):
        self.client = client
        self.headers = CaseInsensitiveDict()
        self._base_url = None
        self.schema = graphene.Schema(query=FakeGithubQuery)

        # Imitate hooks dict. This will be unused and ignored in the tests.
        self.hooks = {
            'response': []
        }

    def build_url(self, *args):
        fakepath = '/'.join(args)
        return FAKE_BASE_URL + fakepath

    def get(self, url, headers=None, params=None):
        request = url
        if request.startswith(FAKE_BASE_URL):
            request = request[len(FAKE_BASE_URL):]

        entity, request = request.split('/', 1)

        if entity == 'repos':
            return self.get_repo(request, params=params)
        else:
            # unknown entity to process
            return None

    def post(self, url, data=None, headers=None, params=None, json=None):

        # Handle graphql
        if json and json.get('query'):
            query = json.get('query')
            variables = json.get('variables')
            result = self.schema.execute(
                query, variables=variables, context=self.client)
            if result.errors:
                # Note that github really returns 200 and an errors field in
                # case of an error.
                return FakeResponse({'errors': result.errors}, 200)
            return FakeResponse({'data': result.data}, 200)

        # Handle creating comments
        match = re.match(r'.+/repos/(.+)/issues/(\d+)/comments$', url)
        if match:
            project, pr_number = match.groups()
            project = urllib.parse.unquote(project)
            self.client._data.reports.append((project, pr_number, 'comment'))
            pull_request = self.client._data.pull_requests[int(pr_number)]
            pull_request.addComment(json['body'])
            return FakeResponse(None, 200)

        # Handle access token creation
        if re.match(r'.*/app/installations/.*/access_tokens', url):
            expiry = (datetime.datetime.now(utc) + datetime.timedelta(
                minutes=60)).replace(microsecond=0).isoformat()
            install_id = url.split('/')[-2]
            data = {
                'token': 'token-%s' % install_id,
                'expires_at': expiry,
            }
            return FakeResponse(data, 201)

        # Handle check run creation
        match = re.match(r'.*/repos/(.*)/check-runs$', url)
        if match:
            if self.client._data.fail_check_run_creation:
                return FakeResponse('Internal server error', 500)

            org, reponame = match.groups()[0].split('/', 1)
            repo = self.client._data.repos.get((org, reponame))

            if repo._permissions.get("checks") is False:
                # To create a proper github3 exception, we need to mock a
                # response object
                return FakeResponse(
                    "Resource not accessible by integration", 403)

            head_sha = json.get('head_sha')
            commit = repo._commits.get(head_sha, None)
            if commit is None:
                commit = FakeCommit(head_sha)
                repo._commits[head_sha] = commit
                repo.check_run_counter += 1
            check_run = commit.set_check_run(
                str(repo.check_run_counter),
                json['name'],
                json['details_url'],
                json['output'],
                json.get('status'),
                json.get('conclusion'),
                json.get('completed_at'),
                json['external_id'],
                json['actions'],
                json.get('app', 'zuul'),
            )

            return FakeResponse(check_run.as_dict(), 201)

        return FakeResponse(None, 404)

    def put(self, url, data=None, headers=None, params=None, json=None):
        # Handle pull request merge
        match = re.match(r'.+/repos/(.+)/pulls/(\d+)/merge$', url)
        if match:
            project, pr_number = match.groups()
            project = urllib.parse.unquote(project)
            pr = self.client._data.pull_requests[int(pr_number)]
            conn = pr.github

            # record that this got reported
            self.client._data.reports.append(
                (pr.project, pr.number, 'merge', json["merge_method"]))
            if conn.merge_failure:
                raise Exception('Unknown merge failure')
            if conn.merge_not_allowed_count > 0:
                conn.merge_not_allowed_count -= 1
                # GitHub returns 405 Method not allowed with more details in
                # the body of the response.
                data = {
                    'message': 'Merge not allowed because of fake reason',
                }
                return FakeResponse(data, 405, 'Method not allowed')
            pr.setMerged(json["commit_message"])
            return FakeResponse({"merged": True}, 200)

        return FakeResponse(None, 404)

    def patch(self, url, data=None, headers=None, params=None, json=None):

        # Handle check run update
        match = re.match(r'.*/repos/(.*)/check-runs/(.*)$', url)
        if match:
            org, reponame = match.groups()[0].split('/', 1)
            check_run_id = match.groups()[1]
            repo = self.client._data.repos.get((org, reponame))

            # Find the specified check run
            check_runs = [
                check_run
                for commit in repo._commits.values()
                for check_run in commit._check_runs
                if check_run.id == check_run_id
            ]
            check_run = check_runs[0]

            check_run.update(json['conclusion'],
                             json['completed_at'],
                             json['output'],
                             json['details_url'],
                             json['external_id'],
                             json['actions'])
            return FakeResponse(check_run.as_dict(), 200)

    def get_repo(self, request, params=None):
        parts = request.split('/', 2)
        if len(parts) == 2:
            org, project = parts
            request = ''
        else:
            org, project, request = parts
        project_name = '{}/{}'.format(org, project)

        repo = self.client.repo_from_project(project_name)

        return repo.get_url(request, params=params)

    def mount(self, prefix, adapter):
        # Don't care in tests
        pass


class FakeBranchProtectionRule:

    def __init__(self):
        self.pattern = None
        self.required_contexts = []
        self.require_reviews = False
        self.require_codeowners_review = False


class FakeGithubData(object):
    def __init__(self, pull_requests):
        self.pull_requests = pull_requests
        self.repos = {}
        self.reports = []
        self.fail_check_run_creation = False

    def __repr__(self):
        return ("pull_requests:%s repos:%s reports:%s "
                "fail_check_run_creation:%s" % (
                    self.pull_requests, self.repos, self.reports,
                    self.fail_check_run_creation))


class FakeGithubClient(object):

    def __init__(self, session=None, data=None):
        self._data = data
        self._inst_id = None
        self.session = FakeGithubSession(self)

    def setData(self, data):
        self._data = data

    def setInstId(self, inst_id):
        self._inst_id = inst_id

    def user(self, login):
        return FakeUser(login)

    def repository(self, owner, proj):
        return self._data.repos.get((owner, proj), None)

    def repo_from_project(self, project):
        # This is a convenience method for the tests.
        owner, proj = project.split('/')
        return self.repository(owner, proj)

    def addProject(self, project):
        owner, proj = project.name.split('/')
        self._data.repos[(owner, proj)] = FakeRepository(
            project.name, self._data)

    def addProjectByName(self, project_name):
        owner, proj = project_name.split('/')
        self._data.repos[(owner, proj)] = FakeRepository(
            project_name, self._data)

    def pull_request(self, owner, project, number):
        fake_pr = self._data.pull_requests[int(number)]
        repo = self.repository(owner, project)
        # Ensure a commit for the head_sha exists so this can be resolved in
        # graphql queries.
        repo._commits.setdefault(
            fake_pr.head_sha,
            FakeCommit(fake_pr.head_sha)
        )
        return FakePull(fake_pr)

    def search_issues(self, query):
        def tokenize(s):
            # Tokenize with handling for quoted substrings.
            # Bit hacky and needs PDA, but our current inputs are
            # constrained enough that this should work.
            s = s[:-len(" type:pr is:open in:body")]
            OR_split = [x.strip() for x in s.split('OR')]
            tokens = [x.strip('"') for x in OR_split]
            return tokens

        def query_is_sha(s):
            return re.match(r'[a-z0-9]{40}', s)

        if query_is_sha(query):
            # Github returns all PR's that contain the sha in their history
            result = []
            for pr in self._data.pull_requests.values():
                # Quick check if head sha matches
                if pr.head_sha == query:
                    result.append(FakeIssueSearchResult(FakeIssue(pr)))
                    continue

                # If head sha doesn't match it still could be in the pr history
                repo = pr._getRepo()
                commits = repo.iter_commits(
                    '%s...%s' % (pr.branch, pr.head_sha))
                for commit in commits:
                    if commit.hexsha == query:
                        result.append(FakeIssueSearchResult(FakeIssue(pr)))
                        continue

            return result

        # Non-SHA queries are of the form:
        #
        #     '"Depends-On: <url>" OR "Depends-On: <url>"
        #      OR ... type:pr is:open in:body'
        #
        # For the tests is currently enough to simply check for the
        # existence of the Depends-On strings in the PR body.
        tokens = tokenize(query)
        terms = set(tokens)
        results = []
        for pr in self._data.pull_requests.values():
            if not pr.body:
                body = ""
            else:
                body = pr.body
            for term in terms:
                if term in body:
                    issue = FakeIssue(pr)
                    results.append(FakeIssueSearchResult(issue))
                    break

        return iter(results)


class FakeGithubEnterpriseClient(FakeGithubClient):

    version = '2.21.0'

    def __init__(self, url, session=None, verify=True):
        super().__init__(session=session)

    def meta(self):
        data = {
            'installed_version': self.version,
        }
        return data