import time
import os.path
import logging
import urllib.parse
from werkzeug.utils import cached_property
from piecrust import (
    RESOURCES_DIR,
    CACHE_DIR, TEMPLATES_DIR, ASSETS_DIR,
    THEME_DIR, PLUGINS_DIR,
    CONFIG_PATH, THEME_CONFIG_PATH)
from piecrust.appconfig import PieCrustConfiguration
from piecrust.cache import ExtensibleCache, NullExtensibleCache
from piecrust.configuration import ConfigurationError
from piecrust.environment import StandardEnvironment
from piecrust.page import Page
from piecrust.plugins.base import PluginLoader
from piecrust.routing import Route


logger = logging.getLogger(__name__)


class PieCrust(object):
    def __init__(self, root_dir, cache=True, debug=False, theme_site=False,
                 env=None, cache_key=None):
        self.root_dir = root_dir
        self.debug = debug
        self.theme_site = theme_site
        self.plugin_loader = PluginLoader(self)
        self.cache_key = cache_key or 'default'

        if cache:
            self.cache = ExtensibleCache(self.cache_dir)
        else:
            self.cache = NullExtensibleCache()

        if env is None:
            env = StandardEnvironment()
        self.env = env
        env.initialize(self)

        stats = env.stats
        stats.registerTimer('SiteConfigLoad')
        stats.registerTimer('PageLoad')
        stats.registerTimer("BuildRenderData")
        stats.registerTimer("BuildLazyPageData")
        stats.registerTimer("PageRender")
        stats.registerTimer("PageRenderSegments")
        stats.registerTimer("PageRenderLayout")
        stats.registerTimer("PageSerialize")
        stats.registerCounter('PageLoads')
        stats.registerCounter('PageRenderSegments')
        stats.registerCounter('PageRenderLayout')

    @cached_property
    def config(self):
        logger.debug("Creating site configuration...")
        start_time = time.perf_counter()

        if not self.theme_site:
            path = os.path.join(self.root_dir, CONFIG_PATH)
        else:
            path = os.path.join(self.root_dir, THEME_CONFIG_PATH)

        theme_path = None
        if not self.theme_site and self.theme_dir:
            theme_path = os.path.join(self.theme_dir, THEME_CONFIG_PATH)

        config_cache = self.cache.getCache('app')
        config = PieCrustConfiguration(
            path=path, theme_path=theme_path,
            cache=config_cache, theme_config=self.theme_site)

        local_path = os.path.join(
            self.root_dir, 'configs', 'local.yml')
        config.addVariant(local_path, raise_if_not_found=False)

        if self.theme_site:
            variant_path = os.path.join(
                self.root_dir, 'configs', 'theme_preview.yml')
            config.addVariant(variant_path, raise_if_not_found=False)

        self.env.stats.stepTimer('SiteConfigLoad',
                                 time.perf_counter() - start_time)
        return config

    @cached_property
    def assets_dirs(self):
        assets_dirs = self._get_configurable_dirs(
            ASSETS_DIR, 'site/assets_dirs')

        # Also add the theme directory, if any.
        if self.theme_dir:
            default_theme_dir = os.path.join(self.theme_dir, ASSETS_DIR)
            if os.path.isdir(default_theme_dir):
                assets_dirs.append(default_theme_dir)

        return assets_dirs

    @cached_property
    def templates_dirs(self):
        templates_dirs = self._get_configurable_dirs(
            TEMPLATES_DIR, 'site/templates_dirs')

        # Also, add the theme directory, if any.
        if self.theme_dir:
            default_theme_dir = os.path.join(self.theme_dir, TEMPLATES_DIR)
            if os.path.isdir(default_theme_dir):
                templates_dirs.append(default_theme_dir)

        return templates_dirs

    @cached_property
    def theme_dir(self):
        # No theme if the curent site is already a theme.
        if self.theme_site:
            return None

        # See if there's a theme we absolutely want.
        td = self._get_dir(THEME_DIR)
        if td is not None:
            return td

        # Try to load a theme specified in the configuration.
        from piecrust.themes.base import ThemeLoader
        loader = ThemeLoader(self.root_dir)
        theme_dir = loader.getThemeDir()
        if theme_dir is not None:
            return theme_dir

        # Nothing... use the default theme.
        return os.path.join(RESOURCES_DIR, 'theme')

    @cached_property
    def plugins_dir(self):
        return self._get_dir(PLUGINS_DIR)

    @cached_property
    def cache_dir(self):
        return os.path.join(self.root_dir, CACHE_DIR, self.cache_key)

    @cached_property
    def sources(self):
        defs = {}
        for cls in self.plugin_loader.getSources():
            defs[cls.SOURCE_NAME] = cls

        sources = []
        for n, s in self.config.get('site/sources').items():
            cls = defs.get(s['type'])
            if cls is None:
                raise ConfigurationError("No such page source type: %s" %
                                         s['type'])
            src = cls(self, n, s)
            sources.append(src)

        return sources

    @cached_property
    def routes(self):
        routes = []
        for r in self.config.get('site/routes'):
            rte = Route(self, r)
            routes.append(rte)
        routes = sorted(routes, key=lambda r: r.pass_num)
        return routes

    @cached_property
    def publishers(self):
        defs_by_name = {}
        defs_by_scheme = {}
        for cls in self.plugin_loader.getPublishers():
            defs_by_name[cls.PUBLISHER_NAME] = cls
            if cls.PUBLISHER_SCHEME:
                defs_by_scheme[cls.PUBLISHER_SCHEME] = cls

        tgts = []
        publish_config = self.config.get('publish')
        if publish_config is None:
            return tgts

        for n, t in publish_config.items():
            pub_class = None
            if isinstance(t, dict):
                pub_type = t.get('type')
                pub_class = defs_by_name[pub_type]
                pub_cfg = t
            elif isinstance(t, str):
                comps = urllib.parse.urlparse(t)
                pub_type = comps.scheme
                pub_class = defs_by_scheme[pub_type]
                pub_cfg = None
            if pub_class is None:
                raise ConfigurationError("No such publisher: %s" % pub_type)

            tgt = pub_class(self, n, pub_cfg)
            if pub_cfg is None:
                tgt.parseUrlTarget(comps)

            tgts.append(tgt)
        return tgts

    def getSource(self, source_name):
        for source in self.sources:
            if source.name == source_name:
                return source

        from piecrust.sources.base import SourceNotFoundError
        raise SourceNotFoundError(source_name)

    def getSourceRoute(self, source_name):
        for route in self.routes:
            if route.source_name == source_name:
                return route

        from piecrust.routing import RouteNotFoundError
        raise RouteNotFoundError(source_name)

    def getPublisher(self, target_name):
        for pub in self.publishers:
            if pub.target == target_name:
                return pub
        return None

    def getPage(self, source, content_item):
        cache_key = '%s@%s' % (source.name, content_item.spec)
        return self.env.page_repository.get(
            cache_key,
            lambda: Page(source, content_item))

    def _get_dir(self, default_rel_dir):
        abs_dir = os.path.join(self.root_dir, default_rel_dir)
        if os.path.isdir(abs_dir):
            return abs_dir
        return None

    def _get_configurable_dirs(self, default_rel_dir, conf_name):
        dirs = []

        # Add custom directories from the configuration.
        conf_dirs = self.config.get(conf_name)
        if conf_dirs is not None:
            if isinstance(conf_dirs, str):
                dirs.append(os.path.join(self.root_dir, conf_dirs))
            else:
                dirs += [os.path.join(self.root_dir, p) for p in conf_dirs]

        # Add the default directory if it exists.
        default_dir = os.path.join(self.root_dir, default_rel_dir)
        if os.path.isdir(default_dir):
            dirs.append(default_dir)

        return dirs


def apply_variants_and_values(app, config_variants=None, config_values=None):
    if config_variants is not None:
        for value in config_variants:
            logger.debug("Adding configuration variant '%s'." % value)
            variant_path = os.path.join(
                app.root_dir, 'configs', '%s.yml' % value)
            app.config.addVariant(variant_path)

    if config_values is not None:
        for name, value in config_values:
            logger.debug("Adding configuration override '%s': %s" %
                         (name, value))
            app.config.addVariantValue(name, value)


class PieCrustFactory(object):
    """ A class that builds a PieCrust app instance.
    """
    def __init__(
            self, root_dir, *,
            cache=True, cache_key=None,
            config_variants=None, config_values=None,
            debug=False, theme_site=False):
        self.root_dir = root_dir
        self.cache = cache
        self.cache_key = cache_key
        self.config_variants = config_variants
        self.config_values = config_values
        self.debug = debug
        self.theme_site = theme_site

    def create(self):
        app = PieCrust(
            self.root_dir,
            cache=self.cache,
            cache_key=self.cache_key,
            debug=self.debug,
            theme_site=self.theme_site)
        apply_variants_and_values(
            app, self.config_variants, self.config_values)
        return app