import getpass
import os
import re
import shutil
import sys
from contextlib import contextmanager
from datetime import datetime
from functools import partial
from importlib import import_module
from subprocess import PIPE, run
from tempfile import TemporaryDirectory

import click
from jinja2 import Environment, PackageLoader

from lektor_ng.utils import locate_executable, slugify

pwd = import_module("pwd") if os.name != "nt" else None


_var_re = re.compile(r"@([^@]+)@")


class Generator:
    def __init__(self, base):
        self.question = 0
        self.jinja_env = Environment(
            loader=PackageLoader("lektor_ng", os.path.join("quickstart-templates", base)),
            line_statement_prefix="%%",
            line_comment_prefix="##",
            variable_start_string="${",
            variable_end_string="}",
            block_start_string="<%",
            block_end_string="%>",
            comment_start_string="/**",
            comment_end_string="**/",
        )
        self.options = {}
        # term width in [1, 78]
        self.term_width = min(max(shutil.get_terminal_size()[0], 1), 78)
        self.e = click.secho
        self.w = partial(click.wrap_text, width=self.term_width)

    @staticmethod
    def abort(message):
        click.echo(f"Error: {message}", err=True)
        raise click.Abort()

    def prompt(self, text, default=None, info=None):
        self.question += 1
        self.e("")
        self.e(f"Step {self.question}:", fg="yellow")
        if info is not None:
            self.e(click.wrap_text(info, self.term_width, "| ", "| "))
        text = "> " + click.style(text, fg="green")

        if default is True or default is False:
            return click.confirm(text, default=default)
        return click.prompt(text, default=default, show_default=True)

    def title(self, title):
        self.e(title, fg="cyan")
        self.e("=" * len(title), fg="cyan")
        self.e("")

    def warn(self, text):
        self.e(self.w(text), fg="magenta")

    def text(self, text):
        self.e(self.w(text))

    def confirm(self, prompt):
        self.e("")
        click.confirm(prompt, default=True, abort=True, prompt_suffix=" ")

    @contextmanager
    def make_target_directory(self, path):
        here = os.path.abspath(os.getcwd())
        path = os.path.abspath(path)
        if here != path:
            try:
                os.makedirs(path)
            except OSError as e:
                self.abort(f"Could not create target folder: {e}")

        if os.path.isdir(path):
            try:
                if len(os.listdir(path)) != 0:
                    raise OSError("Directory not empty")
            except OSError as e:
                self.abort(f"Bad target folder: {e}")

        with TemporaryDirectory() as scratch:
            yield scratch

            # Use shutil.move here in case we move across a file system
            # boundary.
            for filename in os.listdir(scratch):
                shutil.move(os.path.join(scratch, filename), os.path.join(path, filename))

    @staticmethod
    def expand_filename(base, ctx, template_filename):
        def _repl(match):
            return ctx[match.group(1)]

        return os.path.join(base, _var_re.sub(_repl, template_filename))[:-3]

    def run(self, ctx, path):
        with self.make_target_directory(path) as scratch:
            for template in self.jinja_env.list_templates():
                if not template.endswith(".in"):
                    continue
                fn = self.expand_filename(scratch, ctx, template)
                tmpl = self.jinja_env.get_template(template)
                rv = tmpl.render(ctx).strip("\r\n")
                if rv:
                    directory = os.path.dirname(fn)
                    try:
                        os.makedirs(directory)
                    except OSError:
                        pass
                    with open(fn, "wb") as f:
                        f.write((rv + "\n").encode("utf-8"))


def get_default_author() -> str:
    """Attempt to guess an the name of the current user."""
    if sys.platform == "win32":
        return getpass.getuser()
    import pwd

    try:
        pw_gecos = pwd.getpwuid(os.getuid()).pw_gecos
    except KeyError:
        pass
    else:
        full_name = pw_gecos.split(",", 1)[0].strip()
        if full_name:
            return full_name

    return getpass.getuser()


def get_default_author_email() -> str | None:
    """Attempt to guess an email address for the current user.

    May return an empty string if not reasonable guess can be made.
    """
    git = locate_executable("git")
    if git:
        proc = run((git, "config", "user.email"), stdout=PIPE, errors="strict", check=False)
        if proc.returncode == 0:
            return proc.stdout.strip()

    email = os.environ.get("EMAIL", "").strip()
    if email:
        return email
    # We could fall back to f"{getpass.getuser()}@{socket.getfqdn()}",
    # but it is probably better just to go with no default in that
    # case.
    return None


def project_quickstart(defaults=None):
    if not defaults:
        defaults = {}

    g = Generator("project")

    g.title("Lektor Quickstart")
    g.text(
        "This wizard will generate a new basic project with some sensible "
        "defaults for getting started quickly.  We just need to go through "
        "a few questions so that the project is set up correctly for you."
    )

    name = defaults.get("name")
    if name is None:
        name = g.prompt(
            "Project Name",
            None,
            "A project needs a name.  The name is primarily used for the admin "
            "UI and some other places to refer to your project to not get "
            "confused if multiple projects exist.  You can change this at "
            "any later point.",
        )

    author_name = g.prompt(
        "Author Name",
        get_default_author(),
        "Your name.  This is used in a few places in the default template "
        "to refer to in the default copyright messages.",
    )

    path = defaults.get("path")
    if path is None:
        default_project_path = os.path.join(os.getcwd(), name)
        path = g.prompt(
            "Project Path",
            default_project_path,
            "This is the path where the project will be located.  You can "
            "move a project around later if you do not like the path.  If "
            "you provide a relative path it will be relative to the working "
            "directory.",
        )
        path = os.path.expanduser(path)

    with_blog = g.prompt(
        "Add Basic Blog",
        True,
        "Do you want to generate a basic blog module?  If you enable this "
        "the models for a very basic blog will be generated.",
    )

    g.confirm("That's all. Create project?")

    g.run(
        {
            "project_name": name,
            "project_slug": slugify(name),
            "project_path": path,
            "with_blog": with_blog,
            "this_year": datetime.utcnow().year,
            "today": datetime.utcnow().strftime("%Y-%m-%d"),
            "author_name": author_name,
        },
        path,
    )


def plugin_quickstart(defaults=None, project=None):
    if defaults is None:
        defaults = {}

    g = Generator("plugin")

    plugin_name = defaults.get("plugin_name")
    if plugin_name is None:
        plugin_name = g.prompt(
            "Plugin Name",
            default=None,
            info="This is the human readable name for this plugin",
        )

    plugin_id = plugin_name.lower()
    plugin_id = plugin_id.removeprefix("lektor")
    plugin_id = plugin_id.removesuffix("plugin")
    plugin_id = slugify(plugin_id)

    path = defaults.get("path")
    if path is None:
        if project is not None:
            default_path = os.path.join(project.tree, "packages", plugin_id)
        else:
            if len(os.listdir(".")) == 0:
                default_path = os.getcwd()
            else:
                default_path = os.path.join(os.getcwd(), plugin_id)
        path = g.prompt(
            "Plugin Path",
            default_path,
            "The place where you want to initialize the plugin",
        )

    author_name = g.prompt(
        "Author Name",
        get_default_author(),
        "Your name as it will be embedded in the plugin metadata.",
    )

    author_email = g.prompt(
        "Author E-Mail",
        get_default_author_email(),
        "Your e-mail address for the plugin info.",
    )

    g.confirm("Create Plugin?")

    g.run(
        {
            "plugin_name": plugin_name,
            "plugin_id": plugin_id,
            "plugin_class": plugin_id.title().replace("-", "") + "Plugin",
            "plugin_module": "lektor_" + plugin_id.replace("-", "_"),
            "author_name": author_name,
            "author_email": author_email,
        },
        path,
    )


def theme_quickstart(defaults=None, project=None):
    if defaults is None:
        defaults = {}

    g = Generator("theme")

    theme_name = defaults.get("theme_name")
    if theme_name is None:
        theme_name = g.prompt(
            "Theme Name",
            default=None,
            info="This is the human readable name for this theme",
        )

    theme_id = theme_name.lower()
    if theme_id != "lektor" and theme_id.startswith("lektor"):
        theme_id = theme_id[6:].strip()
    if theme_id != "theme" and theme_id.startswith("theme"):
        theme_id = theme_id[5:]
    if theme_id != "theme" and theme_id.endswith("theme"):
        theme_id = theme_id[:-5]
    theme_id = slugify(theme_id)

    path = defaults.get("path")
    if path is None:
        if project is not None:
            default_path = os.path.join(project.tree, "themes", f"lektor-theme-{theme_id}")
        else:
            if len(os.listdir(".")) == 0:
                default_path = os.getcwd()
            else:
                default_path = os.path.join(os.getcwd(), theme_id)
        path = g.prompt(
            "Theme Path",
            default_path,
            "The place where you want to initialize the theme",
        )

    author_name = g.prompt(
        "Author Name",
        get_default_author(),
        "Your name as it will be embedded in the theme metadata.",
    )

    author_email = g.prompt(
        "Author E-Mail",
        get_default_author_email(),
        "Your e-mail address for the theme info.",
    )

    g.confirm("Create Theme?")

    g.run(
        {
            "theme_name": theme_name,
            "theme_id": theme_id,
            "author_name": author_name,
            "author_email": author_email,
        },
        path,
    )

    # symlink
    theme_dir = os.getcwd()
    example_themes = os.path.join(path, "example-site/themes")
    os.makedirs(example_themes)
    os.chdir(example_themes)
    try:
        os.symlink(
            f"../../../lektor-theme-{theme_id}",
            f"lektor-theme-{theme_id}",
        )
    except OSError as exc:
        # Windows, by default, only allows members of the "Administrators" group
        # to create symlinks. For users who are not allowed to create symlinks,
        # error Code 1314 - "A required privilege is not held by the client"
        # is raised.
        if getattr(exc, "winerror", None) != 1314:
            raise
        g.warn("Could not automatically make a symlink to have your example-siteeasily pick up your theme.")
    os.chdir(theme_dir)

    # Sample image
    os.makedirs(os.path.join(path, "images"))
    source_image_path = os.path.join(
        os.path.dirname(os.path.realpath(__file__)),
        "quickstart-templates/theme/images/homepage.png",
    )
    destination_image_path = os.path.join(path, "images/homepage.png")
    with open(source_image_path, "rb") as f:
        image = f.read()
    with open(destination_image_path, "wb") as f:
        f.write(image)