#!/usr/bin/env python3
#
#  Copyright (C) 2016 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 multiprocessing  # for cpu_count()
from collections import Mapping
from . import utils
from . import _site
from . import _yaml
from ._profile import Topics, profile_start, profile_end
from ._exceptions import LoadError, LoadErrorReason
from ._options import OptionPool


# The base BuildStream format version
#
# This version is bumped whenever enhancements are made
# to the ``project.conf`` format or the format in general.
#
BST_FORMAT_VERSION = 0

# The base BuildStream artifact version
#
# The artifact version changes whenever the cache key
# calculation algorithm changes in an incompatible way
# or if buildstream was changed in a way which can cause
# the same cache key to produce something that is no longer
# the same.
BST_ARTIFACT_VERSION = 0

# The separator we use for user specified aliases
_ALIAS_SEPARATOR = ':'


# Project()
#
# The Project Configuration
#
class Project():

    def __init__(self, directory, context):

        # The project name
        self.name = None

        # The project directory
        self.directory = os.path.abspath(directory)

        # Absolute path to where elements are loaded from within the project
        self.element_path = None

        self._context = context  # The invocation Context
        self._variables = {}     # The default variables overridden with project wide overrides
        self._environment = {}   # The base sandbox environment
        self._elements = {}      # Element specific configurations
        self._aliases = {}       # Aliases dictionary
        self._workspaces = {}    # Workspaces
        self._plugin_source_paths = []   # Paths to custom sources
        self._plugin_element_paths = []  # Paths to custom plugins
        self._options = None    # Project options, the OptionPool
        self._cache_key = None
        self._source_format_versions = {}
        self._element_format_versions = {}

        profile_start(Topics.LOAD_PROJECT, self.directory.replace(os.sep, '-'))
        self._load()
        profile_end(Topics.LOAD_PROJECT, self.directory.replace(os.sep, '-'))

    # translate_url():
    #
    # Translates the given url which may be specified with an alias
    # into a fully qualified url.
    #
    # Args:
    #    url (str): A url, which may be using an alias
    #
    # Returns:
    #    str: The fully qualified url, with aliases resolved
    #
    # This method is provided for :class:`.Source` objects to resolve
    # fully qualified urls based on the shorthand which is allowed
    # to be specified in the YAML
    def translate_url(self, url):
        if url and _ALIAS_SEPARATOR in url:
            url_alias, url_body = url.split(_ALIAS_SEPARATOR, 1)
            alias_url = self._aliases.get(url_alias)
            if alias_url:
                url = alias_url + url_body

        return url

    # _load():
    #
    # Loads the project configuration file in the project directory.
    #
    # Raises: LoadError if there was a problem with the project.conf
    #
    def _load(self):

        # Load builtin default
        projectfile = os.path.join(self.directory, "project.conf")
        config = _yaml.load(_site.default_project_config)

        # Load project local config and override the builtin
        project_conf = _yaml.load(projectfile)
        _yaml.composite(config, project_conf)

        # Element type configurations will be composited later onto element types,
        # so we delete it from here and run our final assertion after.
        self._elements = _yaml.node_get(config, Mapping, 'elements', default_value={})
        config.pop('elements', None)
        _yaml.node_final_assertions(config)
        _yaml.node_validate(config, [
            'required-versions',
            'element-path', 'variables',
            'environment', 'environment-nocache',
            'split-rules', 'elements', 'plugins',
            'aliases', 'name',
            'artifacts', 'options',
        ])

        # The project name, element path and option declarations
        # are constant and cannot be overridden by option conditional statements
        self.name = _yaml.node_get(config, str, 'name')
        self.element_path = os.path.join(
            self.directory,
            _yaml.node_get(config, str, 'element-path', default_value='.')
        )

        # Load project options
        options_node = _yaml.node_get(config, Mapping, 'options', default_value={})
        self._options = OptionPool(self.element_path)
        self._options.load(options_node)

        # Collect option values specified in the user configuration
        overrides = self._context._get_overrides(self.name)
        override_options = _yaml.node_get(overrides, Mapping, 'options', default_value={})
        self._options.load_values(override_options, self._context._cli_options)

        # We're done modifying options, now we can use them for substitutions
        self._options.resolve()

        #
        # Now resolve any conditionals in the remaining configuration,
        # any conditionals specified for project option declarations,
        # or conditionally specifying the project name; will be ignored.
        #
        self._options.process_node(config)

        #
        # Now all YAML composition is done, from here on we just load
        # the values from our loaded configuration dictionary.
        #

        # Load artifacts pull/push configuration for this project
        artifacts = _yaml.node_get(config, Mapping, 'artifacts', default_value={})
        _yaml.node_validate(artifacts, ['url'])
        self.artifact_url = _yaml.node_get(artifacts, str, 'url', default_value='') or None

        # Workspace configurations
        self._workspaces = self._load_workspace_config()

        # Version requirements
        versions = _yaml.node_get(config, Mapping, 'required-versions', default_value={})
        _yaml.node_validate(versions, ['project', 'elements', 'sources'])

        # Assert project version first
        format_version = _yaml.node_get(versions, int, 'project', default_value=0)
        if BST_FORMAT_VERSION < format_version:
            major, minor = utils.get_bst_version()
            raise LoadError(
                LoadErrorReason.UNSUPPORTED_PROJECT,
                "Project requested format version {}, but BuildStream {}.{} only supports up until format version {}"
                .format(format_version, major, minor, BST_FORMAT_VERSION))

        # The source versions
        source_versions = _yaml.node_get(versions, Mapping, 'sources', default_value={})
        for key, _ in _yaml.node_items(source_versions):
            self._source_format_versions[key] = _yaml.node_get(source_versions, int, key)

        # The element versions
        element_versions = _yaml.node_get(versions, Mapping, 'elements', default_value={})
        for key, _ in _yaml.node_items(element_versions):
            self._element_format_versions[key] = _yaml.node_get(element_versions, int, key)

        # Load the plugin paths
        plugins = _yaml.node_get(config, Mapping, 'plugins', default_value={})
        _yaml.node_validate(plugins, ['elements', 'sources'])
        self._plugin_source_paths = [os.path.join(self.directory, path)
                                     for path in self._extract_plugin_paths(plugins, 'sources')]
        self._plugin_element_paths = [os.path.join(self.directory, path)
                                      for path in self._extract_plugin_paths(plugins, 'elements')]

        # Source url aliases
        self._aliases = _yaml.node_get(config, Mapping, 'aliases', default_value={})

        # Load base variables
        self._variables = _yaml.node_get(config, Mapping, 'variables')

        # Extend variables with automatic variables and option exports
        self._variables['max-jobs'] = multiprocessing.cpu_count()

        # Export options into variables, if that was requested
        for _, option in self._options.options.items():
            if option.variable:
                self._variables[option.variable] = option.get_value()

        # Load sandbox configuration
        self._environment = _yaml.node_get(config, Mapping, 'environment')
        self._env_nocache = _yaml.node_get(config, list, 'environment-nocache')

        # Load project split rules
        self._splits = _yaml.node_get(config, Mapping, 'split-rules')

    # _list_workspaces()
    #
    # Generator function to enumerate workspaces.
    #
    # Yields:
    #    A tuple in the following format: (element, source, path).
    def _list_workspaces(self):
        for element, _ in _yaml.node_items(self._workspaces):
            for source, _ in _yaml.node_items(self._workspaces[element]):
                yield (element, int(source), self._workspaces[element][source])

    # _get_workspace()
    #
    # Get the path of the workspace source associated with the given
    # element's source at the given index
    #
    # Args:
    #    element (str) - The element name
    #    index (int) - The source index
    #
    # Returns:
    #    None if no workspace is open, the path to the workspace
    #    otherwise
    #
    def _get_workspace(self, element, index):
        try:
            return self._workspaces[element][index]
        except KeyError:
            return None

    # _set_workspace()
    #
    # Set the path of the workspace associated with the given
    # element's source at the given index
    #
    # Args:
    #    element (str) - The element name
    #    index (int) - The source index
    #    path (str) - The path to set the workspace to
    #
    def _set_workspace(self, element, index, path):
        if element.name not in self._workspaces:
            self._workspaces[element.name] = {}

        self._workspaces[element.name][index] = path
        element._set_source_workspace(index, path)

    # _delete_workspace()
    #
    # Remove the workspace from the workspace element. Note that this
    # does *not* remove the workspace from the stored yaml
    # configuration, call _save_workspace_config() afterwards.
    #
    # Args:
    #    element (str) - The element name
    #    index (int) - The source index
    #
    def _delete_workspace(self, element, index):
        del self._workspaces[element][index]

        # Contains a provenance object
        if len(self._workspaces[element]) == 1:
            del self._workspaces[element]

    # _load_workspace_config()
    #
    # Load the workspace configuration and return a node containing
    # all open workspaces for the project
    #
    # Returns:
    #
    #    A node containing a dict that assigns projects to their
    #    workspaces. For example:
    #
    #        amhello.bst: {
    #            0: /home/me/automake,
    #            1: /home/me/amhello
    #        }
    #
    def _load_workspace_config(self):
        os.makedirs(os.path.join(self.directory, ".bst"), exist_ok=True)
        workspace_file = os.path.join(self.directory, ".bst", "workspaces.yml")
        try:
            open(workspace_file, "a").close()
        except IOError as e:
            raise LoadError(LoadErrorReason.MISSING_FILE,
                            "Could not load workspace config: {}".format(e)) from e

        return _yaml.load(workspace_file)

    # _save_workspace_config()
    #
    # Dump the current workspace element to the project configuration
    # file. This makes any changes performed with _delete_workspace or
    # _set_workspace permanent
    #
    def _save_workspace_config(self):
        _yaml.dump(_yaml.node_sanitize(self._workspaces),
                   os.path.join(self.directory, ".bst", "workspaces.yml"))

    def _extract_plugin_paths(self, node, name):
        if not node:
            return
        path_list = _yaml.node_get(node, list, name, default_value=[])
        for i in range(len(path_list)):
            path = _yaml.node_get(node, str, name, indices=[i])
            yield path

    # _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
            # (currently nothing here)
            self._cache_key = utils._generate_key({})

        return self._cache_key