import collections
import importlib
import importlib.util  # to make the type checker happy
import os
import re
import sys
from fnmatch import fnmatch
from os.path import isfile, join
from pathlib import Path
from urllib.parse import parse_qs

import flask

from . import _validate
from ._callback_context import context_value
from ._get_app import get_app
from ._get_paths import get_relative_path
from ._utils import AttributeDict

CONFIG = AttributeDict()
PAGE_REGISTRY = collections.OrderedDict()


def _infer_image(module):
    """
    Return:
    - A page specific image: `assets/<module>.<extension>` is used, e.g. `assets/weekly_analytics.png`
    - A generic app image at `assets/app.<extension>`
    - A logo at `assets/logo.<extension>`
    """
    assets_folder = CONFIG.assets_folder
    valid_extensions = ["apng", "avif", "gif", "jpeg", "jpg", "png", "svg", "webp"]
    page_id = module.split(".")[-1]
    files_in_assets = []

    if os.path.exists(assets_folder):
        files_in_assets = [
            f for f in os.listdir(assets_folder) if isfile(join(assets_folder, f))
        ]
    app_file = None
    logo_file = None
    for fn in files_in_assets:
        fn_without_extension, _, extension = fn.partition(".")
        if extension.lower() in valid_extensions:
            if (
                fn_without_extension == page_id
                or fn_without_extension == page_id.replace("_", "-")
            ):
                return fn

            if fn_without_extension == "app":
                app_file = fn

            if fn_without_extension == "logo":
                logo_file = fn

    if app_file:
        return app_file

    return logo_file


def _module_name_to_page_name(module_name):
    return module_name.split(".")[-1].replace("_", " ").capitalize()


def _infer_path(module_name, template):
    if template is None:
        if CONFIG.pages_folder:
            pages_module = str(Path(CONFIG.pages_folder).name)
            path = (
                module_name.split(pages_module)[-1]
                .replace("_", "-")
                .replace(".", "/")
                .lower()
            )
        else:
            path = module_name.replace("_", "-").replace(".", "/").lower()
    else:
        # replace the variables in the template with "none" to create a default path if
        # no path is supplied
        path = re.sub("<.*?>", "none", template)
    path = "/" + path if not path.startswith("/") else path
    return path


def _module_name_is_package(module_name):
    if module_name not in sys.modules:
        return False
    file = sys.modules[module_name].__file__
    return file and file.endswith("__init__.py")


def _path_to_module_name(path):
    return str(path).replace(".py", "").strip(os.sep).replace(os.sep, ".")


def _infer_module_name(page_path):
    relative_path = page_path.split(CONFIG.pages_folder)[-1]
    module = _path_to_module_name(relative_path)
    proj_root = flask.helpers.get_root_path(CONFIG.name)
    if CONFIG.pages_folder.startswith(proj_root):
        parent_path = CONFIG.pages_folder[len(proj_root) :]
    else:
        parent_path = CONFIG.pages_folder
    parent_module = _path_to_module_name(parent_path)

    module_name = f"{parent_module}.{module}"
    if _module_name_is_package(CONFIG.name):
        # Only prefix with CONFIG.name when it's an imported package name
        module_name = f"{CONFIG.name}.{module_name}"
    return module_name


def _parse_query_string(search):
    if not search or not search.startswith("?"):
        return {}

    query_string = search[1:]

    parsed_qs = parse_qs(query_string, keep_blank_values=True)

    return {k: v[0] if len(v) == 1 else v for k, v in parsed_qs.items()}


def _parse_path_variables(pathname, path_template):
    """
    creates the dict of path variables passed to the layout
    e.g. path_template= "/asset/<asset_id>"
         if pathname provided by the browser is "/assets/a100"
         returns **{"asset_id": "a100"}
    """

    # parse variable definitions e.g. <var_name> from template
    # and create pattern to match
    wildcard_pattern = re.sub("<.*?>", "*", path_template)
    var_pattern = re.sub("<.*?>", "(.*)", path_template)

    # check that static sections of the pathname match the template
    if not fnmatch(pathname, wildcard_pattern):
        return None

    # parse variable names e.g. var_name from template
    var_names = re.findall("<(.*?)>", path_template)

    # parse variables from path
    variables = re.findall(var_pattern, pathname)
    variables = variables[0] if isinstance(variables[0], tuple) else variables

    return dict(zip(var_names, variables))


def _create_redirect_function(redirect_to):
    def redirect():
        return flask.redirect(redirect_to, code=301)

    return redirect


def _set_redirect(redirect_from, path):
    app = get_app()
    if redirect_from and len(redirect_from):
        for redirect in redirect_from:
            fullname = app.get_relative_path(redirect)
            app.server.add_url_rule(
                fullname,
                fullname,
                _create_redirect_function(app.get_relative_path(path)),
            )


def register_page(
    module,
    path=None,
    path_template=None,
    name=None,
    order=None,
    title=None,
    description=None,
    image=None,
    image_url=None,
    redirect_from=None,
    layout=None,
    **kwargs,
):
    """
    Assigns the variables to `dash.page_registry` as an `OrderedDict`
    (ordered by `order`).

    `dash.page_registry` is used by `pages_plugin` to set up the layouts as
    a multi-page Dash app. This includes the URL routing callbacks
    (using `dcc.Location`) and the HTML templates to include title,
    meta description, and the meta description image.

    `dash.page_registry` can also be used by Dash developers to create the
    page navigation links or by template authors.

    - `module`:
       The module path where this page's `layout` is defined. Often `__name__`.

    - `path`:
       URL Path, e.g. `/` or `/home-page`.
       If not supplied, will be inferred from the `path_template` or `module`,
       e.g. based on path_template: `/asset/<asset_id` to `/asset/none`
       e.g. based on module: `pages.weekly_analytics` to `/weekly-analytics`

    - `relative_path`:
        The path with `requests_pathname_prefix` prefixed before it.
        Use this path when specifying local URL paths that will work
        in environments regardless of what `requests_pathname_prefix` is.
        In some deployment environments, like Dash Enterprise,
        `requests_pathname_prefix` is set to the application name,
        e.g. `my-dash-app`.
        When working locally, `requests_pathname_prefix` might be unset and
        so a relative URL like `/page-2` can just be `/page-2`.
        However, when the app is deployed to a URL like `/my-dash-app`, then
        `relative_path` will be `/my-dash-app/page-2`.

    - `path_template`:
       Add variables to a URL by marking sections with <variable_name>. The layout function
       then receives the <variable_name> as a keyword argument.
       e.g. path_template= "/asset/<asset_id>"
            then if pathname in browser is "/assets/a100" then layout will receive **{"asset_id":"a100"}

    - `name`:
       The name of the link.
       If not supplied, will be inferred from `module`,
       e.g. `pages.weekly_analytics` to `Weekly analytics`

    - `order`:
       The order of the pages in `page_registry`.
       If not supplied, then the filename is used and the page with path `/` has
       order `0`

    - `title`:
       (string or function) Specifies the page title displayed in the browser tab.
        If not supplied, the app's title is used if different from the default "Dash".
        Otherwise, the title is the given `name` or inferred from the module name.
        For example, `pages.weekly_analytics` is inferred as "Weekly Analytics".

    - `description`:
       (string or function) The <meta type="description"></meta>.
       If not defined, the application description will be used if available.

    - `image`:
       The meta description image used by social media platforms.
       If not supplied, then it looks for the following images in `assets/`:
        - A page specific image: `assets/<module>.<extension>` is used, e.g. `assets/weekly_analytics.png`
        - A generic app image at `assets/app.<extension>`
        - A logo at `assets/logo.<extension>`
        When inferring the image file, it will look for the following extensions:
        APNG, AVIF, GIF, JPEG, JPG, PNG, SVG, WebP.

    -  `image_url`:
       Overrides the image property and sets the `<image>` meta tag to the provided image URL.

    - `redirect_from`:
       A list of paths that should redirect to this page.
       For example: `redirect_from=['/v2', '/v3']`

    - `layout`:
       The layout function or component for this page.
       If not supplied, then looks for `layout` from within the supplied `module`.

    - `**kwargs`:
       Arbitrary keyword arguments that can be stored

    ***

    `page_registry` stores the original property that was passed in under
    `supplied_<property>` and the coerced property under `<property>`.
    For example, if this was called:
    ```
    register_page(
        'pages.historical_outlook',
        name='Our historical view',
        custom_key='custom value'
    )
    ```
    Then this will appear in `page_registry`:
    ```
    OrderedDict([
        (
            'pages.historical_outlook',
            dict(
                module='pages.historical_outlook',

                supplied_path=None,
                path='/historical-outlook',

                supplied_name='Our historical view',
                name='Our historical view',

                supplied_title=None,
                title='Our historical view'

                supplied_layout=None,
                layout=<function pages.historical_outlook.layout>,

                custom_key='custom value'
            )
        ),
    ])
    ```
    """
    if context_value.get().get("ignore_register_page"):
        return

    _validate.validate_use_pages(CONFIG)

    page = dict(
        module=_validate.validate_module_name(module),
        supplied_path=path,
        path_template=path_template,
        path=path if path is not None else _infer_path(module, path_template),
        supplied_name=name,
        name=name if name is not None else _module_name_to_page_name(module),
    )
    page.update(
        supplied_title=title,
        title=title
        if title is not None
        else CONFIG.title
        if CONFIG.title != "Dash"
        else page["name"],
    )
    page.update(
        description=description
        if description
        else CONFIG.description
        if CONFIG.description
        else "",
        order=order,
        supplied_order=order,
        supplied_layout=layout,
        **kwargs,
    )
    page.update(
        supplied_image=image,
        image=(image if image is not None else _infer_image(module)),
        image_url=image_url,
    )
    page.update(redirect_from=_set_redirect(redirect_from, page["path"]))

    PAGE_REGISTRY[module] = page

    if page["path_template"]:
        _validate.validate_template(page["path_template"])

    if layout is not None:
        # Override the layout found in the file set during `plug`
        PAGE_REGISTRY[module]["layout"] = layout

    # set home page order
    order_supplied = any(
        p["supplied_order"] is not None for p in PAGE_REGISTRY.values()
    )

    for p in PAGE_REGISTRY.values():
        p["order"] = (
            0 if p["path"] == "/" and not order_supplied else p["supplied_order"]
        )
        p["relative_path"] = get_relative_path(p["path"])

    # Sort numeric orders first, then string orders, then no order,
    # finally by module name for matching orders
    for page in sorted(
        PAGE_REGISTRY.values(),
        key=lambda i: (
            i["order"] is None,  # False (order given) sorts before True
            i["order"] if isinstance(i["order"], (int, float)) else float("inf"),
            str(i["order"]),
            i["module"],
        ),
    ):
        PAGE_REGISTRY.move_to_end(page["module"])


def _path_to_page(path_id):
    path_variables = None
    for page in PAGE_REGISTRY.values():
        if page["path_template"]:
            template_id = page["path_template"].strip("/")
            path_variables = _parse_path_variables(path_id, template_id)
            if path_variables:
                return page, path_variables
        if path_id == page["path"].strip("/"):
            return page, path_variables
    return {}, None


def _page_meta_tags(app):
    start_page, path_variables = _path_to_page(flask.request.path.strip("/"))

    # use the supplied image_url or create url based on image in the assets folder
    image = start_page.get("image", "")
    if image:
        image = app.get_asset_url(image)
    assets_image_url = (
        "".join([flask.request.url_root, image.lstrip("/")]) if image else None
    )
    supplied_image_url = start_page.get("image_url")
    image_url = supplied_image_url if supplied_image_url else assets_image_url

    title = start_page.get("title", app.title)
    if callable(title):
        title = title(**path_variables) if path_variables else title()

    description = start_page.get("description", "")
    if callable(description):
        description = description(**path_variables) if path_variables else description()

    return [
        {"name": "description", "content": description},
        {"property": "twitter:card", "content": "summary_large_image"},
        {"property": "twitter:url", "content": flask.request.url},
        {"property": "twitter:title", "content": title},
        {"property": "twitter:description", "content": description},
        {"property": "twitter:image", "content": image_url or ""},
        {"property": "og:title", "content": title},
        {"property": "og:type", "content": "website"},
        {"property": "og:description", "content": description},
        {"property": "og:image", "content": image_url or ""},
    ]


def _import_layouts_from_pages(pages_folder):
    for root, dirs, files in os.walk(pages_folder):
        dirs[:] = [d for d in dirs if not d.startswith(".") and not d.startswith("_")]
        for file in files:
            if file.startswith("_") or file.startswith(".") or not file.endswith(".py"):
                continue
            page_path = os.path.join(root, file)
            with open(page_path, encoding="utf-8") as f:
                content = f.read()
                if "register_page" not in content:
                    continue

            module_name = _infer_module_name(page_path)
            spec = importlib.util.spec_from_file_location(module_name, page_path)
            page_module = importlib.util.module_from_spec(spec)  # type: ignore[reportArgumentType]
            spec.loader.exec_module(page_module)  # type: ignore[reportOptionalMemberAccess]
            sys.modules[module_name] = page_module

            if (
                module_name in PAGE_REGISTRY
                and not PAGE_REGISTRY[module_name]["supplied_layout"]
            ):
                _validate.validate_pages_layout(module_name, page_module)
                PAGE_REGISTRY[module_name]["layout"] = getattr(page_module, "layout")
