# Copyright (C) 2017  Lars Wirzenius
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


import apifw


import ick2


class ControllerAPI:

    def __init__(self):
        self._state = ick2.ControllerState()

    def get_state_directory(self):
        return self._state.get_state_directory()

    def set_state_directory(self, dirname):
        self._state.set_state_directory(dirname)

    def find_missing_route(self, missing_path):  # pragma: no cover
        apis = {
            '/version': VersionAPI,
            '/builds': BuildsAPI,
            '/logs': LogAPI,
            '/projects': ProjectAPI,
            '/work': WorkAPI,
            '/workers': WorkerAPI,
        }

        routes = []
        for path in apis:
            self._state.load_resources(path[1:])
            api = apis[path](self._state)
            routes.extend(api.get_routes(path))
        ick2.log.log('info', msg_texg='Found routes', routes=routes)
        return routes


class APIbase:  # pragma: no cover

    def __init__(self, state):
        self._state = state

    def get_routes(self, path):
        return [
            {
                'method': 'POST',
                'path': path,
                'callback': self.POST(self.create),
            },
            {
                'method': 'GET',
                'path': path,
                'callback': self.GET(self.list),
            },
            {
                'method': 'GET',
                'path': '{}/<name>'.format(path),
                'callback': self.GET(self.show),
            },
            {
                'method': 'PUT',
                'path': '{}/<name>'.format(path),
                'callback': self.PUT(self.update),
            },
            {
                'method': 'DELETE',
                'path': '{}/<name>'.format(path),
                'callback': self.DELETE(self.delete),
            },
        ]

    def GET(self, callback):
        def wrapper(content_type, body, **kwargs):
            ick2.log.log(
                'trace', msg_text='GET called', kwargs=kwargs,
                content_type=content_type, body=body)
            try:
                if 'raw_uri_path' in kwargs:
                    del kwargs['raw_uri_path']
                    body = callback(**kwargs)
            except ick2.NotFound as e:
                return not_found(e)
            if isinstance(body, dict):
                return OK(body)
            elif isinstance(body, str):
                return text_plain(body)
            raise Exception('this must not happen')
        return wrapper

    def POST(self, callback):
        def wrapper(content_type, body, **kwargs):
            ick2.log.log(
                'trace', msg_text='POST called', kwargs=kwargs,
                content_type=content_type, body=body)
            body = callback(body)
            ick2.log.log('trace', msg_text='returned body', body=repr(body))
            return created(body)
        return wrapper

    def PUT(self, callback):
        def wrapper(content_type, body, **kwargs):
            ick2.log.log(
                'trace', msg_text='PUT called', kwargs=kwargs,
                content_type=content_type, body=body)
            if 'raw_uri_path' in kwargs:
                del kwargs['raw_uri_path']
            try:
                body = callback(body, **kwargs)
            except ick2.NotFound as e:
                return not_found(e)
            except ick2.WrongPipelineStatus as e:
                ick2.log.log(
                    'error',
                    msg_text='Wrong state for pipeline',
                    exception=str(e))
                return bad_request(e)
            ick2.log.log('trace', msg_text='returned body', body=repr(body))
            return OK(body)
        return wrapper

    def DELETE(self, callback):
        def wrapper(content_type, body, **kwargs):
            ick2.log.log(
                'trace', msg_text='DELETE called', kwargs=kwargs,
                content_type=content_type, body=body)
            try:
                if 'raw_uri_path' in kwargs:
                    del kwargs['raw_uri_path']
                body = callback(**kwargs)
            except ick2.NotFound as e:
                return not_found(e)
            return OK(body)
        return wrapper

    def create(self, body):
        raise NotImplementedError()

    def update(self, body, name):
        raise NotImplementedError()

    def delete(self, name):
        raise NotImplementedError()

    def list(self):
        raise NotImplementedError()

    def show(self, name):
        raise NotImplementedError()


class VersionAPI(APIbase):

    def __init__(self, state):
        super().__init__(state)

    def get_routes(self, path):  # pragma: no cover
        return [
            {
                'method': 'GET',
                'path': path,
                'callback': self.GET(self.get_version),
            }
        ]

    def get_version(self):
        return {'version': ick2.__version__}

    def create(self, *args):  # pragma: no cover
        pass

    def update(self, *args):  # pragma: no cover
        pass

    def delete(self, *args):  # pragma: no cover
        pass

    def list(self):  # pragma: no cover
        pass

    def show(self, *args):  # pragma: no cover
        pass


class ResourceApiBase(APIbase):

    def __init__(self, type_name, state):
        super().__init__(state)
        self._type_name = type_name

    def list(self):
        return {
            self._type_name: self._state.get_resources(self._type_name),
        }

    def show(self, name):
        return self._state.get_resource(self._type_name, name)

    def create(self, body):
        return self._state.add_resource(
            self._type_name, self.get_resource_name(body), body)

    def get_resource_name(self, resource):  # pragma: no cover
        raise NotImplementedError

    def update(self, body, name):
        return self._state.update_resource(self._type_name, name, body)

    def delete(self, name):
        self._state.remove_resource(self._type_name, name)


class WorkerAPI(ResourceApiBase):  # pragma: no cover

    def __init__(self, state):
        super().__init__('workers', state)

    def get_resource_name(self, resource):
        return resource['worker']


class BuildsAPI(ResourceApiBase):  # pragma: no cover

    def __init__(self, state):
        super().__init__('builds', state)

    def get_resource_name(self, resource):
        return resource['build']

    def create(self, body):  # pragma: no cover
        raise MethodNotAllowed('Creating builds directly is not allowed')

    def update(self, body, name):  # pragma: no cover
        raise MethodNotAllowed('Updating builds directly is not allowed')

    def list(self):
        result = super().list()
        items = result[self._type_name]
        items.sort(key=lambda x: x.get('build_id'))
        result[self._type_name] = items
        return result


class LogAPI(ResourceApiBase):  # pragma: no cover

    def __init__(self, state):
        super().__init__('log', state)

    def get_resource_name(self, resource):
        return resource['log']

    def create(self, body):  # pragma: no cover
        raise MethodNotAllowed('Creating builds directly is not allowed')

    def update(self, body, name):  # pragma: no cover
        raise MethodNotAllowed('Updating builds directly is not allowed')

    def show(self, name):
        log = self._state.get_resource('log', str(name))
        ick2.log.log('info', msg_text='Returning log', log=log)
        return log['log']


class ProjectAPI(ResourceApiBase):

    def __init__(self, state):
        super().__init__('projects', state)

    def get_resource_name(self, resource):
        return resource['project']

    def get_routes(self, path):  # pragma: no cover
        return super().get_routes(path) + self.get_pipeline_routes(path)

    def get_pipeline_routes(self, path):  # pragma: no cover
        pipeline_path = '{}/<project>/pipelines/<pipeline>'.format(path)
        builds_path = '{}/<project>/builds'.format(path)
        return [
            {
                'method': 'GET',
                'path': pipeline_path,
                'callback': self.GET(self.get_pipeline),
            },
            {
                'method': 'PUT',
                'path': pipeline_path,
                'callback': self.PUT(self.set_pipeline_callback),
            },
            {
                'method': 'GET',
                'path': builds_path,
                'callback': self.GET(self.get_builds),
            },
        ]

    def get_pipeline(self, project, pipeline):
        p = self._state.get_resource(self._type_name, project)
        for pl in p['pipelines']:
            if pl['name'] == pipeline:
                return {
                    'status': pl.get('status', 'idle'),
                }
        raise ick2.NotFound()

    def set_pipeline_callback(
            self, body, project, pipeline):  # pragma: no cover
        return self.set_pipeline(body['status'], project, pipeline)

    def set_pipeline(self, state, project, pipeline):
        allowed_changes = {
            'idle': 'triggered',
            'triggered': 'building',
            'building': 'idle',
        }
        p = self._state.get_resource(self._type_name, project)
        for pl in p['pipelines']:
            if pl['name'] == pipeline:
                old_state = pl.get('status', 'idle')
                if allowed_changes[old_state] != state:
                    raise ick2.WrongPipelineStatus(state)
                pl['status'] = state
                self._state.update_resource(self._type_name, project, p)
                return {'status': state}
        raise ick2.NotFound()

    def get_builds(self, project):
        p = self._state.get_resource(self._type_name, project)
        return {
            'project': project,
            'builds': p.get('builds', []),
        }


class WorkAPI(APIbase):

    def __init__(self, state):
        super().__init__(state)
        self._type_name = 'work'

    def get_routes(self, path):  # pragma: no cover
        return [
            {
                'method': 'GET',
                'path': '{}/<worker>'.format(path),
                'callback': self.GET(self.get_work),
            },
            {
                'method': 'POST',
                'path': path,
                'callback': self.POST(self.update_work),
            },
        ]

    def get_work(self, worker):
        worker_state = self._get_worker(worker)
        if not worker_state.get('doing'):
            project, pipeline = self._pick_triggered_pipeline()
            if project is None:
                doing = {}
            else:
                pipeline['status'] = 'building'
                self._update_project(project)

                build_id = self._start_build(project, pipeline, worker)
                self._start_log(build_id)

                index = 0
                doing = {
                    'build_id': build_id,
                    'worker': worker,
                    'project': project['project'],
                    'pipeline': pipeline['name'],
                    'step': pipeline['actions'][index],
                    'step_index': index,
                    'log': '/logs/{}'.format(build_id),
                }

            worker_state = {
                'worker': worker,
                'doing': doing,
            }
            self._update_worker(worker_state)

        return worker_state['doing']

    def _get_worker(self, worker):  # pragma: no cover
        try:
            return self._state.get_resource('workers', worker)
        except ick2.NotFound:
            return {
                'worker': worker,
            }

    def _update_worker(self, worker_state):
        self._state.update_resource(
            'workers', worker_state['worker'], worker_state)

    def _pick_triggered_pipeline(self):
        projects = self._get_projects()
        for project in projects:
            for pipeline in project['pipelines']:
                if pipeline.get('status') == 'triggered':
                    return project, pipeline
        return None, None

    def _get_projects(self):
        return self._state.get_resources('projects')

    def _update_project(self, project):
        self._state.update_resource('projects', project['project'], project)

    def update_work(self, update):
        if 'worker' not in update:  # pragma: no cover
            raise BadUpdate('no worker specified')

        worker_state = self._get_worker(update['worker'])
        doing = worker_state.get('doing', {})
        self._check_work_update(doing, update)

        project, pipeline = self._get_pipeline(
            update['project'], update['pipeline'])
        self._append_to_build_log(update)

        ick2.log.log(
            'trace',
            msg_text='xxx update_work',
            update=update,
            project=project,
            pipeline=pipeline,
            doing=doing)

        exit_code = update.get('exit_code')
        if exit_code == 0:
            index = doing['step_index'] + 1
            actions = pipeline['actions']
            if index >= len(actions):
                pipeline['status'] = 'idle'
                doing = {}
                self._finish_build(update)
            else:
                doing['step_index'] = index
                doing['step'] = actions[index]
            self._update_project(project)

            worker_state = {
                'worker': update['worker'],
                'doing': doing,
            }
            self._update_worker(worker_state)
        elif exit_code is not None:
            assert isinstance(exit_code, int)
            assert exit_code != 0
            pipeline['status'] = 'idle'
            self._update_project(project)
            self._finish_build(update)

            worker_state = {
                'worker': update['worker'],
                'doing': {},
            }
            self._update_worker(worker_state)

    def _check_work_update(self, doing, update):  # pragma: no cover
        must_match = ['worker', 'project', 'pipeline', 'build_id']
        for name in must_match:
            if name not in update:
                raise BadUpdate('{} not specified'.format(name))
            if doing.get(name) != update[name]:
                raise BadUpdate(
                    '{} differs from current work: {} vs {}'.format(
                        name, doing.get(name), update[name]))

    def _get_pipeline(self, project, pipeline):  # pragma: no cover
        projects = self._get_projects()
        for p in projects:
            for pl in p['pipelines']:
                if pl.get('name') == pipeline:
                    return p, pl
        raise ick2.NotFound()

    def _start_build(self, project, pipeline, worker):
        ick2.log.log('info', msg_text='Starting new build')
        build_id = project.get('build_id', 0)
        build_id += 1
        project['build_id'] = build_id
        self._update_project(project)
        build = {
            'build_id': build_id,
            'log': '/logs/{}'.format(build_id),
            'worker': worker,
            'project': project['project'],
            'pipeline': pipeline['name'],
            'status': 'building',
        }
        self._state.add_resource('builds', str(build_id), build)
        return build_id

    def _start_log(self, build_id):
        ick2.log.log('info', msg_text='Starting new log', build_id=build_id)
        log = {
            'build_id': build_id,
            'log': '',
        }
        self._state.add_resource('log', str(build_id), log)
        return build_id

    def _append_to_build_log(self, update):
        build_id = update['build_id']
        log = self._state.get_resource('log', str(build_id))
        for kind in ['stdout', 'stderr']:
            text = update.get(kind, '')
            if text is not None:
                log['log'] += text
        self._state.update_resource('log', str(build_id), log)

    def _finish_build(self, update):
        build = self._state.get_resource('builds', str(update['build_id']))
        build['status'] = update['exit_code']
        self._state.update_resource('builds', str(update['build_id']), build)

    def create(self, *args, **kwargs):  # pragma: no cover
        pass

    def update(self, *args, **kwargs):  # pragma: no cover
        pass

    def list(self, *args, **kwargs):  # pragma: no cover
        pass

    def show(self, *args, **kwargs):  # pragma: no cover
        pass

    def delete(self, *args, **kwargs):  # pragma: no cover
        pass


class BadUpdate(Exception):  # pragma: no cover

    def __init__(self, how):
        super().__init__('Work update is BAD: {}'.format(how))


class MethodNotAllowed(Exception):  # pragma: no cover

    def __init__(self, wat):
        super().__init__(wat)


def response(status_code, body, headers):  # pragma: no cover
    obj = {
        'status': status_code,
        'body': body,
        'headers': headers,
    }
    return apifw.Response(obj)


def OK(body):  # pragma: no cover
    headers = {
        'Content-Type': 'application/json',
    }
    return response(apifw.HTTP_OK, body, headers)


def text_plain(body):  # pragma: no cover
    headers = {
        'Content-Type': 'text/plain',
    }
    return response(apifw.HTTP_OK, body, headers)


def not_found(error):  # pragma: no cover
    headers = {
        'Content-Type': 'text/plain',
    }
    return response(apifw.HTTP_NOT_FOUND, str(error), headers)


def bad_request(error):  # pragma: no cover
    headers = {
        'Content-Type': 'text/plain',
    }
    return response(apifw.HTTP_BAD_REQUEST, str(error), headers)


def created(body):  # pragma: no cover
    headers = {
        'Content-Type': 'application/json',
    }
    return response(apifw.HTTP_CREATED, body, headers)