#
#  Copyright (C) 2016-2018 Codethink Limited
#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU Lesser General Public
#  License as published by the Free Software Foundation; either
#  version 2 of the License, or (at your option) any later version.
#
#  This library 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
#  Lesser General Public License for more details.
#
#  You should have received a copy of the GNU Lesser General Public
#  License along with this library. If not, see <http://www.gnu.org/licenses/>.
#
#  Authors:
#        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>

import os
import shutil
import datetime
from collections import deque
from contextlib import contextmanager
from . import utils
from . import _cachekey
from . import _signals
from . import _site
from . import _yaml
from ._exceptions import LoadError, LoadErrorReason, BstError
from ._message import Message, MessageType
from ._profile import Topics, PROFILER
from ._artifactcache import ArtifactCache
from ._sourcecache import SourceCache
from ._cas import CASCache, CASQuota, CASCacheUsage
from ._workspaces import Workspaces, WorkspaceProjectCache
from .plugin import Plugin
from .sandbox import SandboxRemote


# Context()
#
# The Context object holds all of the user preferences
# and context for a given invocation of BuildStream.
#
# This is a collection of data from configuration files and command
# line arguments and consists of information such as where to store
# logs and artifacts, where to perform builds and cache downloaded sources,
# verbosity levels and basically anything pertaining to the context
# in which BuildStream was invoked.
#
# Args:
#    directory (str): The directory that buildstream was invoked in
#
class Context():

    def __init__(self, directory=None):

        # Filename indicating which configuration file was used, or None for the defaults
        self.config_origin = None

        # The directory under which other directories are based
        self.cachedir = None

        # The directory where various sources are stored
        self.sourcedir = None

        # specs for source cache remotes
        self.source_cache_specs = None

        # The directory where build sandboxes will be created
        self.builddir = None

        # The directory for CAS
        self.casdir = None

        # The directory for artifact protos
        self.artifactdir = None

        # The directory for temporary files
        self.tmpdir = None

        # Default root location for workspaces
        self.workspacedir = None

        # The locations from which to push and pull prebuilt artifacts
        self.artifact_cache_specs = None

        # The global remote execution configuration
        self.remote_execution_specs = None

        # The directory to store build logs
        self.logdir = None

        # The abbreviated cache key length to display in the UI
        self.log_key_length = None

        # Whether debug mode is enabled
        self.log_debug = None

        # Whether verbose mode is enabled
        self.log_verbose = None

        # Maximum number of lines to print from build logs
        self.log_error_lines = None

        # Maximum number of lines to print in the master log for a detailed message
        self.log_message_lines = None

        # Format string for printing the pipeline at startup time
        self.log_element_format = None

        # Format string for printing message lines in the master log
        self.log_message_format = None

        # Maximum number of fetch or refresh tasks
        self.sched_fetchers = None

        # Maximum number of build tasks
        self.sched_builders = None

        # Maximum number of push tasks
        self.sched_pushers = None

        # Maximum number of retries for network tasks
        self.sched_network_retries = None

        # What to do when a build fails in non interactive mode
        self.sched_error_action = None

        # Size of the artifact cache in bytes
        self.config_cache_quota = None

        # User specified cache quota, used for display messages
        self.config_cache_quota_string = None

        # Whether or not to attempt to pull build trees globally
        self.pull_buildtrees = None

        # Whether or not to cache build trees on artifact creation
        self.cache_buildtrees = None

        # Whether directory trees are required for all artifacts in the local cache
        self.require_artifact_directories = True

        # Whether file contents are required for all artifacts in the local cache
        self.require_artifact_files = True

        # Whether elements must be rebuilt when their dependencies have changed
        self._strict_build_plan = None

        # Make sure the XDG vars are set in the environment before loading anything
        self._init_xdg()

        # Private variables
        self._cache_key = None
        self._message_handler = None
        self._message_depth = deque()
        self._artifactcache = None
        self._sourcecache = None
        self._projects = []
        self._project_overrides = _yaml.new_empty_node()
        self._workspaces = None
        self._workspace_project_cache = WorkspaceProjectCache()
        self._log_handle = None
        self._log_filename = None
        self._cascache = None
        self._casquota = None
        self._directory = directory

    # load()
    #
    # Loads the configuration files
    #
    # Args:
    #    config (filename): The user specified configuration file, if any
    #

    # Raises:
    #   LoadError
    #
    # This will first load the BuildStream default configuration and then
    # override that configuration with the configuration file indicated
    # by *config*, if any was specified.
    #
    @PROFILER.profile(Topics.LOAD_CONTEXT, "load")
    def load(self, config=None):
        # If a specific config file is not specified, default to trying
        # a $XDG_CONFIG_HOME/buildstream.conf file
        #
        if not config:
            default_config = os.path.join(os.environ['XDG_CONFIG_HOME'],
                                          'buildstream.conf')
            if os.path.exists(default_config):
                config = default_config

        # Load default config
        #
        defaults = _yaml.load(_site.default_user_config)

        if config:
            self.config_origin = os.path.abspath(config)
            user_config = _yaml.load(config)
            _yaml.composite(defaults, user_config)

        # Give obsoletion warnings
        if 'builddir' in defaults:
            raise LoadError(LoadErrorReason.INVALID_DATA,
                            "builddir is obsolete, use cachedir")

        if 'artifactdir' in defaults:
            raise LoadError(LoadErrorReason.INVALID_DATA,
                            "artifactdir is obsolete")

        _yaml.node_validate(defaults, [
            'cachedir', 'sourcedir', 'builddir', 'logdir', 'scheduler',
            'artifacts', 'source-caches', 'logging', 'projects', 'cache', 'prompt',
            'workspacedir', 'remote-execution',
        ])

        for directory in ['cachedir', 'sourcedir', 'logdir', 'workspacedir']:
            # Allow the ~ tilde expansion and any environment variables in
            # path specification in the config files.
            #
            path = defaults.get_str(directory)
            path = os.path.expanduser(path)
            path = os.path.expandvars(path)
            path = os.path.normpath(path)
            setattr(self, directory, path)

        # add directories not set by users
        self.tmpdir = os.path.join(self.cachedir, 'tmp')
        self.casdir = os.path.join(self.cachedir, 'cas')
        self.builddir = os.path.join(self.cachedir, 'build')
        self.artifactdir = os.path.join(self.cachedir, 'artifacts', 'refs')

        # Move old artifact cas to cas if it exists and create symlink
        old_casdir = os.path.join(self.cachedir, 'artifacts', 'cas')
        if (os.path.exists(old_casdir) and not os.path.islink(old_casdir) and
                not os.path.exists(self.casdir)):
            os.rename(old_casdir, self.casdir)
            os.symlink(self.casdir, old_casdir)

        # Cleanup old extract directories
        old_extractdirs = [os.path.join(self.cachedir, 'artifacts', 'extract'),
                           os.path.join(self.cachedir, 'extract')]
        for old_extractdir in old_extractdirs:
            if os.path.isdir(old_extractdir):
                shutil.rmtree(old_extractdir, ignore_errors=True)

        # Load quota configuration
        # We need to find the first existing directory in the path of our
        # cachedir - the cachedir may not have been created yet.
        cache = defaults.get_mapping('cache')
        _yaml.node_validate(cache, ['quota', 'pull-buildtrees', 'cache-buildtrees'])

        self.config_cache_quota_string = cache.get_str('quota')
        try:
            self.config_cache_quota = utils._parse_size(self.config_cache_quota_string,
                                                        self.casdir)
        except utils.UtilError as e:
            raise LoadError(LoadErrorReason.INVALID_DATA,
                            "{}\nPlease specify the value in bytes or as a % of full disk space.\n"
                            "\nValid values are, for example: 800M 10G 1T 50%\n"
                            .format(str(e))) from e

        # Load artifact share configuration
        self.artifact_cache_specs = ArtifactCache.specs_from_config_node(defaults)

        # Load source cache config
        self.source_cache_specs = SourceCache.specs_from_config_node(defaults)

        self.remote_execution_specs = SandboxRemote.specs_from_config_node(defaults)

        # Load pull build trees configuration
        self.pull_buildtrees = cache.get_bool('pull-buildtrees')

        # Load cache build trees configuration
        self.cache_buildtrees = _node_get_option_str(
            cache, 'cache-buildtrees', ['always', 'auto', 'never'])

        # Load logging config
        logging = defaults.get_mapping('logging')
        _yaml.node_validate(logging, [
            'key-length', 'verbose',
            'error-lines', 'message-lines',
            'debug', 'element-format', 'message-format'
        ])
        self.log_key_length = logging.get_int('key-length')
        self.log_debug = logging.get_bool('debug')
        self.log_verbose = logging.get_bool('verbose')
        self.log_error_lines = logging.get_int('error-lines')
        self.log_message_lines = logging.get_int('message-lines')
        self.log_message_lines = logging.get_int('message-lines')
        self.log_element_format = logging.get_str('element-format')
        self.log_message_format = logging.get_str('message-format')

        # Load scheduler config
        scheduler = defaults.get_mapping('scheduler')
        _yaml.node_validate(scheduler, [
            'on-error', 'fetchers', 'builders',
            'pushers', 'network-retries'
        ])
        self.sched_error_action = _node_get_option_str(
            scheduler, 'on-error', ['continue', 'quit', 'terminate'])
        self.sched_fetchers = scheduler.get_int('fetchers')
        self.sched_builders = scheduler.get_int('builders')
        self.sched_pushers = scheduler.get_int('pushers')
        self.sched_network_retries = scheduler.get_int('network-retries')

        # Load per-projects overrides
        self._project_overrides = defaults.get_mapping('projects', default={})

        # Shallow validation of overrides, parts of buildstream which rely
        # on the overrides are expected to validate elsewhere.
        for overrides in self._project_overrides.values():
            _yaml.node_validate(overrides,
                                ['artifacts', 'source-caches', 'options',
                                 'strict', 'default-mirror',
                                 'remote-execution'])

    @property
    def artifactcache(self):
        if not self._artifactcache:
            self._artifactcache = ArtifactCache(self)

        return self._artifactcache

    # get_cache_usage()
    #
    # Fetches the current usage of the artifact cache
    #
    # Returns:
    #     (CASCacheUsage): The current status
    #
    def get_cache_usage(self):
        return CASCacheUsage(self.get_casquota())

    @property
    def sourcecache(self):
        if not self._sourcecache:
            self._sourcecache = SourceCache(self)

        return self._sourcecache

    # add_project():
    #
    # Add a project to the context.
    #
    # Args:
    #    project (Project): The project to add
    #
    def add_project(self, project):
        if not self._projects:
            self._workspaces = Workspaces(project, self._workspace_project_cache)
        self._projects.append(project)

    # get_projects():
    #
    # Return the list of projects in the context.
    #
    # Returns:
    #    (list): The list of projects
    #
    def get_projects(self):
        return self._projects

    # get_toplevel_project():
    #
    # Return the toplevel project, the one which BuildStream was
    # invoked with as opposed to a junctioned subproject.
    #
    # Returns:
    #    (Project): The Project object
    #
    def get_toplevel_project(self):
        return self._projects[0]

    # get_workspaces():
    #
    # Return a Workspaces object containing a list of workspaces.
    #
    # Returns:
    #    (Workspaces): The Workspaces object
    #
    def get_workspaces(self):
        return self._workspaces

    # get_workspace_project_cache():
    #
    # Return the WorkspaceProjectCache object used for this BuildStream invocation
    #
    # Returns:
    #    (WorkspaceProjectCache): The WorkspaceProjectCache object
    #
    def get_workspace_project_cache(self):
        return self._workspace_project_cache

    # get_overrides():
    #
    # Fetch the override dictionary for the active project. This returns
    # a node loaded from YAML.
    #
    # Args:
    #    project_name (str): The project name
    #
    # Returns:
    #    (MappingNode): The overrides dictionary for the specified project
    #
    def get_overrides(self, project_name):
        return self._project_overrides.get_mapping(project_name, default={})

    # get_strict():
    #
    # Fetch whether we are strict or not
    #
    # Returns:
    #    (bool): Whether or not to use strict build plan
    #
    def get_strict(self):
        if self._strict_build_plan is None:
            # Either we're not overridden or we've never worked it out before
            # so work out if we should be strict, and then cache the result
            toplevel = self.get_toplevel_project()
            overrides = self.get_overrides(toplevel.name)
            self._strict_build_plan = overrides.get_bool('strict', default=True)

        # If it was set by the CLI, it overrides any config
        # Ditto if we've already computed this, then we return the computed
        # value which we cache here too.
        return self._strict_build_plan

    # get_cache_key():
    #
    # Returns the cache key, calculating it if necessary
    #
    # Returns:
    #    (str): A hex digest cache key for the Context
    #
    def get_cache_key(self):
        if self._cache_key is None:

            # Anything that alters the build goes into the unique key
            self._cache_key = _cachekey.generate_key({})

        return self._cache_key

    # set_message_handler()
    #
    # Sets the handler for any status messages propagated through
    # the context.
    #
    # The message handler should have the same signature as
    # the message() method
    def set_message_handler(self, handler):
        self._message_handler = handler

    # silent_messages():
    #
    # Returns:
    #    (bool): Whether messages are currently being silenced
    #
    def silent_messages(self):
        for silent in self._message_depth:
            if silent:
                return True
        return False

    # message():
    #
    # Proxies a message back to the caller, this is the central
    # point through which all messages pass.
    #
    # Args:
    #    message: A Message object
    #
    def message(self, message):

        # Tag message only once
        if message.depth is None:
            message.depth = len(list(self._message_depth))

        # If we are recording messages, dump a copy into the open log file.
        self._record_message(message)

        # Send it off to the log handler (can be the frontend,
        # or it can be the child task which will propagate
        # to the frontend)
        assert self._message_handler

        self._message_handler(message, context=self)

    # silence()
    #
    # A context manager to silence messages, this behaves in
    # the same way as the `silent_nested` argument of the
    # Context._timed_activity() context manager: especially
    # important messages will not be silenced.
    #
    @contextmanager
    def silence(self):
        self._push_message_depth(True)
        try:
            yield
        finally:
            self._pop_message_depth()

    # timed_activity()
    #
    # Context manager for performing timed activities and logging those
    #
    # Args:
    #    context (Context): The invocation context object
    #    activity_name (str): The name of the activity
    #    detail (str): An optional detailed message, can be multiline output
    #    silent_nested (bool): If specified, nested messages will be silenced
    #
    @contextmanager
    def timed_activity(self, activity_name, *, unique_id=None, detail=None, silent_nested=False):

        starttime = datetime.datetime.now()
        stopped_time = None

        def stop_time():
            nonlocal stopped_time
            stopped_time = datetime.datetime.now()

        def resume_time():
            nonlocal stopped_time
            nonlocal starttime
            sleep_time = datetime.datetime.now() - stopped_time
            starttime += sleep_time

        with _signals.suspendable(stop_time, resume_time):
            try:
                # Push activity depth for status messages
                message = Message(unique_id, MessageType.START, activity_name, detail=detail)
                self.message(message)
                self._push_message_depth(silent_nested)
                yield

            except BstError:
                # Note the failure in status messages and reraise, the scheduler
                # expects an error when there is an error.
                elapsed = datetime.datetime.now() - starttime
                message = Message(unique_id, MessageType.FAIL, activity_name, elapsed=elapsed)
                self._pop_message_depth()
                self.message(message)
                raise

            elapsed = datetime.datetime.now() - starttime
            message = Message(unique_id, MessageType.SUCCESS, activity_name, elapsed=elapsed)
            self._pop_message_depth()
            self.message(message)

    # recorded_messages()
    #
    # Records all messages in a log file while the context manager
    # is active.
    #
    # In addition to automatically writing all messages to the
    # specified logging file, an open file handle for process stdout
    # and stderr will be available via the Context.get_log_handle() API,
    # and the full logfile path will be available via the
    # Context.get_log_filename() API.
    #
    # Args:
    #     filename (str): A logging directory relative filename,
    #                     the pid and .log extension will be automatically
    #                     appended
    #
    # Yields:
    #     (str): The fully qualified log filename
    #
    @contextmanager
    def recorded_messages(self, filename):

        # We dont allow recursing in this context manager, and
        # we also do not allow it in the main process.
        assert self._log_handle is None
        assert self._log_filename is None
        assert not utils._is_main_process()

        # Create the fully qualified logfile in the log directory,
        # appending the pid and .log extension at the end.
        self._log_filename = os.path.join(self.logdir,
                                          '{}.{}.log'.format(filename, os.getpid()))

        # Ensure the directory exists first
        directory = os.path.dirname(self._log_filename)
        os.makedirs(directory, exist_ok=True)

        with open(self._log_filename, 'a') as logfile:

            # Write one last line to the log and flush it to disk
            def flush_log():

                # If the process currently had something happening in the I/O stack
                # then trying to reenter the I/O stack will fire a runtime error.
                #
                # So just try to flush as well as we can at SIGTERM time
                try:
                    logfile.write('\n\nForcefully terminated\n')
                    logfile.flush()
                except RuntimeError:
                    os.fsync(logfile.fileno())

            self._log_handle = logfile
            with _signals.terminator(flush_log):
                yield self._log_filename

            self._log_handle = None
            self._log_filename = None

    # get_log_handle()
    #
    # Fetches the active log handle, this will return the active
    # log file handle when the Context.recorded_messages() context
    # manager is active
    #
    # Returns:
    #     (file): The active logging file handle, or None
    #
    def get_log_handle(self):
        return self._log_handle

    # get_log_filename()
    #
    # Fetches the active log filename, this will return the active
    # log filename when the Context.recorded_messages() context
    # manager is active
    #
    # Returns:
    #     (str): The active logging filename, or None
    #
    def get_log_filename(self):
        return self._log_filename

    # set_artifact_directories_optional()
    #
    # This indicates that the current context (command or configuration)
    # does not require directory trees of all artifacts to be available in the
    # local cache.
    #
    def set_artifact_directories_optional(self):
        self.require_artifact_directories = False
        self.require_artifact_files = False

    # set_artifact_files_optional()
    #
    # This indicates that the current context (command or configuration)
    # does not require file contents of all artifacts to be available in the
    # local cache.
    #
    def set_artifact_files_optional(self):
        self.require_artifact_files = False

    # _record_message()
    #
    # Records the message if recording is enabled
    #
    # Args:
    #    message (Message): The message to record
    #
    def _record_message(self, message):

        if self._log_handle is None:
            return

        INDENT = "    "
        EMPTYTIME = "--:--:--"
        template = "[{timecode: <8}] {type: <7}"

        # If this message is associated with a plugin, print what
        # we know about the plugin.
        plugin_name = ""
        if message.unique_id:
            template += " {plugin}"
            plugin = Plugin._lookup(message.unique_id)
            plugin_name = plugin.name

        template += ": {message}"

        detail = ''
        if message.detail is not None:
            template += "\n\n{detail}"
            detail = message.detail.rstrip('\n')
            detail = INDENT + INDENT.join(detail.splitlines(True))

        timecode = EMPTYTIME
        if message.message_type in (MessageType.SUCCESS, MessageType.FAIL):
            hours, remainder = divmod(int(message.elapsed.total_seconds()), 60**2)
            minutes, seconds = divmod(remainder, 60)
            timecode = "{0:02d}:{1:02d}:{2:02d}".format(hours, minutes, seconds)

        text = template.format(timecode=timecode,
                               plugin=plugin_name,
                               type=message.message_type.upper(),
                               message=message.message,
                               detail=detail)

        # Write to the open log file
        self._log_handle.write('{}\n'.format(text))
        self._log_handle.flush()

    # _push_message_depth() / _pop_message_depth()
    #
    # For status messages, send the depth of timed
    # activities inside a given task through the message
    #
    def _push_message_depth(self, silent_nested):
        self._message_depth.appendleft(silent_nested)

    def _pop_message_depth(self):
        assert self._message_depth
        self._message_depth.popleft()

    # Force the resolved XDG variables into the environment,
    # this is so that they can be used directly to specify
    # preferred locations of things from user configuration
    # files.
    def _init_xdg(self):
        if not os.environ.get('XDG_CACHE_HOME'):
            os.environ['XDG_CACHE_HOME'] = os.path.expanduser('~/.cache')
        if not os.environ.get('XDG_CONFIG_HOME'):
            os.environ['XDG_CONFIG_HOME'] = os.path.expanduser('~/.config')
        if not os.environ.get('XDG_DATA_HOME'):
            os.environ['XDG_DATA_HOME'] = os.path.expanduser('~/.local/share')

    def get_cascache(self):
        if self._cascache is None:
            self._cascache = CASCache(self.cachedir)
        return self._cascache

    def get_casquota(self):
        if self._casquota is None:
            self._casquota = CASQuota(self)
        return self._casquota


# _node_get_option_str()
#
# Like Node.get_scalar().as_str(), but also checks value is one of the allowed option
# strings. Fetches a value from a dictionary node, and makes sure it's one of
# the pre-defined options.
#
# Args:
#    node (dict): The dictionary node
#    key (str): The key to get a value for in node
#    allowed_options (iterable): Only accept these values
#
# Returns:
#    The value, if found in 'node'.
#
# Raises:
#    LoadError, when the value is not of the expected type, or is not found.
#
def _node_get_option_str(node, key, allowed_options):
    result = node.get_str(key)
    if result not in allowed_options:
        provenance = _yaml.node_get_provenance(node, key)
        raise LoadError(LoadErrorReason.INVALID_DATA,
                        "{}: {} should be one of: {}".format(
                            provenance, key, ", ".join(allowed_options)))
    return result