import codecs
import os
from copy import deepcopy
from typing import Any, Iterable, List, Optional, Type, Union

import jinja2
import pkg_resources

from . import exceptions, fmt, plugins, utils
from .__about__ import __version__
from .types import Config, ConfigValue

TEMPLATES_ROOT = pkg_resources.resource_filename("tutor", "templates")
VERSION_FILENAME = "version"
BIN_FILE_EXTENSIONS = [".ico", ".jpg", ".png", ".ttf", ".woff", ".woff2"]


class JinjaEnvironment(jinja2.Environment):
    loader: jinja2.BaseLoader

    def __init__(self, template_roots: List[str]) -> None:
        loader = jinja2.FileSystemLoader(template_roots)
        super().__init__(loader=loader, undefined=jinja2.StrictUndefined)


class Renderer:
    @classmethod
    def instance(cls: Type["Renderer"], config: Config) -> "Renderer":
        # Load template roots: these are required to be able to use
        # {% include .. %} directives
        template_roots = [TEMPLATES_ROOT]
        for plugin in plugins.iter_enabled(config):
            if plugin.templates_root:
                template_roots.append(plugin.templates_root)

        return cls(config, template_roots, ignore_folders=["partials"])

    def __init__(
        self,
        config: Config,
        template_roots: List[str],
        ignore_folders: Optional[List[str]] = None,
    ):
        self.config = deepcopy(config)
        self.template_roots = template_roots
        self.ignore_folders = ignore_folders or []
        self.ignore_folders.append(".git")

        # Create environment
        environment = JinjaEnvironment(template_roots)
        environment.filters["common_domain"] = utils.common_domain
        environment.filters["encrypt"] = utils.encrypt
        environment.filters["list_if"] = utils.list_if
        environment.filters["long_to_base64"] = utils.long_to_base64
        environment.globals["iter_values_named"] = self.iter_values_named
        environment.globals["patch"] = self.patch
        environment.filters["random_string"] = utils.random_string
        environment.filters["reverse_host"] = utils.reverse_host
        environment.globals["rsa_import_key"] = utils.rsa_import_key
        environment.filters["rsa_private_key"] = utils.rsa_private_key
        environment.filters["walk_templates"] = self.walk_templates
        environment.globals["TUTOR_VERSION"] = __version__
        self.environment = environment

    def iter_templates_in(self, *prefix: str) -> Iterable[str]:
        """
        The elements of `prefix` must contain only "/", and not os.sep.
        """
        full_prefix = "/".join(prefix)
        env_templates: List[str] = self.environment.loader.list_templates()
        for template in env_templates:
            if template.startswith(full_prefix) and self.is_part_of_env(template):
                yield template

    def iter_values_named(
        self,
        prefix: Optional[str] = None,
        suffix: Optional[str] = None,
        allow_empty: bool = False,
    ) -> Iterable[ConfigValue]:
        """
        Iterate on all config values for which the name match the given pattern.

        Note that here we only iterate on the values, not the key names. Empty
        values (those that evaluate to boolean `false`) will not be yielded, unless
        `allow_empty` is True.
        TODO document this in the plugins API
        """
        for var_name, value in self.config.items():
            if prefix is not None and not var_name.startswith(prefix):
                continue
            if suffix is not None and not var_name.endswith(suffix):
                continue
            if not allow_empty and not value:
                continue
            yield value

    def walk_templates(self, subdir: str) -> Iterable[str]:
        """
        Iterate on the template files from `templates/<subdir>`.

        Yield:
            path: template path relative to the template root
        """
        yield from self.iter_templates_in(subdir + "/")

    def is_part_of_env(self, path: str) -> bool:
        """
        Determines whether a template should be rendered or not. Note that here we don't
        rely on the OS separator, as we are handling templates
        """
        parts = path.split("/")
        basename = parts[-1]
        is_excluded = False
        is_excluded = (
            is_excluded or basename.startswith(".") or basename.endswith(".pyc")
        )
        is_excluded = is_excluded or basename == "__pycache__"
        for ignore_folder in self.ignore_folders:
            is_excluded = is_excluded or ignore_folder in parts
        return not is_excluded

    def find_os_path(self, template_name: str) -> str:
        path = template_name.replace("/", os.sep)
        for templates_root in self.template_roots:
            full_path = os.path.join(templates_root, path)
            if os.path.exists(full_path):
                return full_path
        raise ValueError("Template path does not exist")

    def patch(self, name: str, separator: str = "\n", suffix: str = "") -> str:
        """
        Render calls to {{ patch("...") }} in environment templates from plugin patches.
        """
        patches = []
        for plugin, patch in plugins.iter_patches(self.config, name):
            try:
                patches.append(self.render_str(patch))
            except exceptions.TutorError:
                fmt.echo_error(
                    "Error rendering patch '{}' from plugin {}".format(name, plugin)
                )
                raise
        rendered = separator.join(patches)
        if rendered:
            rendered += suffix
        return rendered

    def render_str(self, text: str) -> str:
        template = self.environment.from_string(text)
        return self.__render(template)

    def render_template(self, template_name: str) -> Union[str, bytes]:
        """
        Render a template file. Return the corresponding string. If it's a binary file
        (as indicated by its path), return bytes.

        The template_name *always* uses "/" separators, and is not os-dependent. Do not pass the result of
        os.path.join(...) to this function.
        """
        if is_binary_file(template_name):
            # Don't try to render binary files
            with open(self.find_os_path(template_name), "rb") as f:
                return f.read()

        try:
            template = self.environment.get_template(template_name)
        except Exception:
            fmt.echo_error("Error loading template " + template_name)
            raise

        try:
            return self.__render(template)
        except (jinja2.exceptions.TemplateError, exceptions.TutorError):
            fmt.echo_error("Error rendering template " + template_name)
            raise
        except Exception:
            fmt.echo_error("Unknown error rendering template " + template_name)
            raise

    def render_all_to(self, root: str, *prefix: str) -> None:
        """
        `prefix` can be used to limit the templates to render.
        """
        for template_name in self.iter_templates_in(*prefix):
            rendered = self.render_template(template_name)
            dst = os.path.join(root, template_name.replace("/", os.sep))
            write_to(rendered, dst)

    def __render(self, template: jinja2.Template) -> str:
        try:
            return template.render(**self.config)
        except jinja2.exceptions.UndefinedError as e:
            raise exceptions.TutorError(
                "Missing configuration value: {}".format(e.args[0])
            )


def save(root: str, config: Config) -> None:
    """
    Save the full environment, including version information.
    """
    root_env = pathjoin(root)
    for prefix in [
        "apps/",
        "build/",
        "dev/",
        "k8s/",
        "local/",
        VERSION_FILENAME,
        "kustomization.yml",
    ]:
        save_all_from(prefix, root_env, config)

    for plugin in plugins.iter_enabled(config):
        if plugin.templates_root:
            save_plugin_templates(plugin, root, config)

    upgrade_obsolete(root)
    fmt.echo_info("Environment generated in {}".format(base_dir(root)))


def upgrade_obsolete(root: str) -> None:
    # tutor.conf was renamed to _tutor.conf in order to be the first config file loaded
    # by nginx
    nginx_tutor_conf = pathjoin(root, "apps", "nginx", "tutor.conf")
    if os.path.exists(nginx_tutor_conf):
        os.remove(nginx_tutor_conf)


def save_plugin_templates(
    plugin: plugins.BasePlugin, root: str, config: Config
) -> None:
    """
    Save plugin templates to plugins/<plugin name>/*.
    Only the "apps" and "build" subfolders are rendered.
    """
    plugins_root = pathjoin(root, "plugins")
    for subdir in ["apps", "build"]:
        subdir_path = os.path.join(plugin.name, subdir)
        save_all_from(subdir_path, plugins_root, config)


def save_all_from(prefix: str, root: str, config: Config) -> None:
    """
    Render the templates that start with `prefix` and store them with the same
    hierarchy at `root`. Here, `prefix` can be the result of os.path.join(...).
    """
    renderer = Renderer.instance(config)
    renderer.render_all_to(root, prefix.replace(os.sep, "/"))


def write_to(content: Union[str, bytes], path: str) -> None:
    """
    Write some content to a path. Content can be either str or bytes.
    """
    utils.ensure_file_directory_exists(path)
    if isinstance(content, bytes):
        with open(path, mode="wb") as of_binary:
            of_binary.write(content)
    else:
        with open(path, mode="w", encoding="utf8", newline="\n") as of_text:
            of_text.write(content)


def render_file(config: Config, *path: str) -> Union[str, bytes]:
    """
    Return the rendered contents of a template.
    """
    renderer = Renderer.instance(config)
    template_name = "/".join(path)
    return renderer.render_template(template_name)


def render_unknown(config: Config, value: Any) -> Any:
    """
    Render an unknown `value` object with the selected config.

    If `value` is a dict, its values are also rendered.
    """
    if isinstance(value, str):
        return render_str(config, value)
    elif isinstance(value, dict):
        return {k: render_unknown(config, v) for k, v in value.items()}
    return value


def render_str(config: Config, text: str) -> str:
    """
    Args:
        text (str)
        config (dict)

    Return:
        substituted (str)
    """
    return Renderer.instance(config).render_str(text)


def check_is_up_to_date(root: str) -> None:
    if not is_up_to_date(root):
        message = (
            "The current environment stored at {} is not up-to-date: it is at "
            "v{} while the 'tutor' binary is at v{}. You should upgrade "
            "the environment by running:\n"
            "\n"
            "    tutor config save"
        )
        fmt.echo_alert(
            message.format(base_dir(root), current_version(root), __version__)
        )


def is_up_to_date(root: str) -> bool:
    """
    Check if the currently rendered version is equal to the current tutor version.
    """
    return current_version(root) == __version__


def needs_major_upgrade(root: str) -> bool:
    """
    Return the current version as a tuple of int. E.g: (1, 0, 2).
    """
    current = int(current_version(root).split(".")[0])
    required = int(__version__.split(".")[0])
    return 0 < current < required


def current_release(root: str) -> str:
    """
    Return the name of the current Open edX release.
    """
    return {"0": "ironwood", "3": "ironwood", "10": "juniper", "11": "koa"}[
        current_version(root).split(".")[0]
    ]


def current_version(root: str) -> str:
    """
    Return the current environment version. If the current environment has no version,
    return "0.0.0".
    """
    path = pathjoin(root, VERSION_FILENAME)
    if not os.path.exists(path):
        return "0.0.0"
    return open(path).read().strip()


def read_template_file(*path: str) -> str:
    """
    Read raw content of template located at `path`.
    """
    src = template_path(*path)
    with codecs.open(src, encoding="utf-8") as fi:
        return fi.read()


def is_binary_file(path: str) -> bool:
    ext = os.path.splitext(path)[1]
    return ext in BIN_FILE_EXTENSIONS


def template_path(*path: str, templates_root: str = TEMPLATES_ROOT) -> str:
    """
    Return the template file's absolute path.
    """
    return os.path.join(templates_root, *path)


def data_path(root: str, *path: str) -> str:
    """
    Return the file's absolute path inside the data directory.
    """
    return os.path.join(root_dir(root), "data", *path)


def pathjoin(root: str, *path: str) -> str:
    """
    Return the file's absolute path inside the environment.
    """
    return os.path.join(base_dir(root), *path)


def base_dir(root: str) -> str:
    """
    Return the environment base directory.
    """
    return os.path.join(root_dir(root), "env")


def root_dir(root: str) -> str:
    """
    Return the project root directory.
    """
    return os.path.abspath(root)
