import asyncio
import mimetypes
from importlib.resources import files
from urllib.parse import unquote
from wsgiref.handlers import format_date_time

import brotli
import sanic.helpers
from blake3 import blake3
from sanic import Blueprint, Sanic, empty, raw
from sanic.exceptions import Forbidden, NotFound

from cista import auth, config, session, watching
from cista.api import bp
from cista.util.apphelpers import handle_sanic_exception

# Workaround until Sanic PR #2824 is merged
sanic.helpers._ENTITY_HEADERS = frozenset()

app = Sanic("cista", strict_slashes=True)
app.blueprint(auth.bp)
app.blueprint(bp)
app.exception(Exception)(handle_sanic_exception)


@app.before_server_start
async def main_start(app, loop):
    config.load_config()
    await watching.start(app, loop)


@app.after_server_stop
async def main_stop(app, loop):
    await watching.stop(app, loop)


@app.on_request
async def use_session(req):
    req.ctx.session = session.get(req)
    try:
        req.ctx.user = config.config.users[req.ctx.session["username"]]  # type: ignore
    except (AttributeError, KeyError, TypeError):
        req.ctx.user = None
    # CSRF protection
    if req.method == "GET" and req.headers.upgrade != "websocket":
        return  # Ordinary GET requests are fine
    # Check that origin matches host, for browsers which should all send Origin.
    # Curl doesn't send any Origin header, so we allow it anyway.
    origin = req.headers.origin
    if origin and origin.split("//", 1)[1] != req.host:
        raise Forbidden("Invalid origin: Cross-Site requests not permitted")


@app.before_server_start
def http_fileserver(app, _):
    bp = Blueprint("fileserver")
    bp.on_request(auth.verify)
    bp.static(
        "/files/",
        config.config.path,
        use_content_range=True,
        stream_large_files=True,
        directory_view=True,
    )
    app.blueprint(bp)


www = {}


@app.before_server_start
async def load_wwwroot(*_ignored):
    global www
    www = await asyncio.get_event_loop().run_in_executor(None, _load_wwwroot, www)


def _load_wwwroot(www):
    wwwnew = {}
    base = files("cista") / "wwwroot"
    paths = ["."]
    while paths:
        path = paths.pop(0)
        current = base / path
        for p in current.iterdir():
            if p.is_dir():
                paths.append(current / p.parts[-1])
                continue
            name = p.relative_to(base).as_posix()
            mime = mimetypes.guess_type(name)[0] or "application/octet-stream"
            mtime = p.stat().st_mtime
            data = p.read_bytes()
            etag = blake3(data).hexdigest(length=8)
            if name == "index.html":
                name = ""
            # Use old data if not changed
            if name in www and www[name][2]["etag"] == etag:
                wwwnew[name] = www[name]
                continue
            # Add charset definition
            if mime.startswith("text/"):
                mime = f"{mime}; charset=UTF-8"
            # Asset files names will change whenever the content changes
            cached = name.startswith("assets/")
            headers = {
                "etag": etag,
                "last-modified": format_date_time(mtime),
                "cache-control": "max-age=31536000, immutable"
                if cached
                else "no-cache",
                "content-type": mime,
            }
            # Precompress with Brotli
            br = brotli.compress(data)
            if len(br) >= len(data):
                br = False
            wwwnew[name] = data, br, headers
    return wwwnew


@app.add_task
async def refresh_wwwroot():
    while True:
        try:
            wwwold = www
            await load_wwwroot()
            changes = ""
            for name in sorted(www):
                attr = www[name]
                if wwwold.get(name) == attr:
                    continue
                headers = attr[2]
                changes += f"{headers['last-modified']} {headers['etag']} /{name}\n"
            for name in sorted(set(wwwold) - set(www)):
                changes += f"Deleted /{name}\n"
            if changes:
                print(f"Updated wwwroot:\n{changes}", end="", flush=True)
        except Exception as e:
            print("Error loading wwwroot", e)
        if not app.debug:
            return
        await asyncio.sleep(0.5)


@app.route("/<path:path>", methods=["GET", "HEAD"])
async def wwwroot(req, path=""):
    """Frontend files only"""
    name = unquote(path)
    if name not in www:
        raise NotFound(f"File not found: /{path}", extra={"name": name})
    data, br, headers = www[name]
    if req.headers.if_none_match == headers["etag"]:
        # The client has it cached, respond 304 Not Modified
        return empty(304, headers=headers)
    # Brotli compressed?
    if br and "br" in req.headers.accept_encoding.split(", "):
        headers = {
            **headers,
            "content-encoding": "br",
        }
        data = br
    return raw(data, headers=headers)