# Copyright: Ankitects Pty Ltd and contributors
# License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
#
# Please see /docs/syncserver.md
#

from __future__ import annotations

import gzip
import os
import socket
import sys
import time
from io import BytesIO
from tempfile import NamedTemporaryFile
from typing import Optional

try:
    import flask
    from waitress.server import create_server
except ImportError as e:
    print(e, "- to use the server, 'pip install anki[syncserver]'")
    sys.exit(1)


from flask import Response

from anki import Collection
from anki._backend.backend_pb2 import SyncServerMethodIn

Method = SyncServerMethodIn.Method  # pylint: disable=no-member

app = flask.Flask(__name__)
col: Collection
trace = os.getenv("TRACE")


def get_request_data() -> bytes:
    buf = BytesIO()
    flask.request.files["data"].save(buf)
    buf.seek(0)
    zip = gzip.GzipFile(mode="rb", fileobj=buf)
    return zip.read()


def get_request_data_into_file() -> bytes:
    "Returns the utf8 path to the resulting file."
    # this could be optimized to stream the data into a file
    # in the future
    data = get_request_data()
    tempobj = NamedTemporaryFile(dir=folder(), delete=False)
    tempobj.write(data)
    tempobj.close()
    return tempobj.name.encode("utf8")


def handle_sync_request(method_str: str) -> Response:
    method = get_method(method_str)
    if method is None:
        raise Exception(f"unknown method: {method_str}")

    if method == Method.FULL_UPLOAD:
        data = get_request_data_into_file()
    else:
        data = get_request_data()
        if trace:
            print("-->", data)

    full = method in (Method.FULL_UPLOAD, Method.FULL_DOWNLOAD)
    if full:
        col.close_for_full_sync()
    try:
        outdata = col.backend.sync_server_method(method=method, data=data)
    except Exception as e:
        if method == Method.META:
            # if parallel syncing requests come in, block them
            print("exception in meta", e)
            return flask.make_response("Conflict", 409)
        else:
            raise
    finally:
        if full:
            after_full_sync()

    resp = None
    if method == Method.FULL_UPLOAD:
        # upload call expects a raw string literal returned
        outdata = b"OK"
    elif method == Method.FULL_DOWNLOAD:
        path = outdata.decode("utf8")

        def stream_reply():
            with open(path, "rb") as f:
                while chunk := f.read(16 * 1024):
                    yield chunk
                os.unlink(path)

        resp = Response(stream_reply())
    else:
        if trace:
            print("<--", outdata)

    if not resp:
        resp = flask.make_response(outdata)
    resp.headers["Content-Type"] = "application/binary"
    return resp


def after_full_sync():
    # the server methods do not reopen the collection after a full sync,
    # so we need to
    col.reopen(after_full_sync=False)
    col.db.rollback()


def get_method(
    method_str: str,
) -> Optional[SyncServerMethodIn.MethodValue]:  # pylint: disable=no-member
    s = method_str
    if s == "hostKey":
        return Method.HOST_KEY
    elif s == "meta":
        return Method.META
    elif s == "start":
        return Method.START
    elif s == "applyGraves":
        return Method.APPLY_GRAVES
    elif s == "applyChanges":
        return Method.APPLY_CHANGES
    elif s == "chunk":
        return Method.CHUNK
    elif s == "applyChunk":
        return Method.APPLY_CHUNK
    elif s == "sanityCheck2":
        return Method.SANITY_CHECK
    elif s == "finish":
        return Method.FINISH
    elif s == "abort":
        return Method.ABORT
    elif s == "upload":
        return Method.FULL_UPLOAD
    elif s == "download":
        return Method.FULL_DOWNLOAD
    else:
        return None


@app.route("/<path:pathin>", methods=["POST"])
def handle_request(pathin: str):
    path = pathin
    print(int(time.time()), flask.request.remote_addr, path)

    if path.startswith("sync/"):
        return handle_sync_request(path.split("/", maxsplit=1)[1])


def folder():
    folder = os.getenv("FOLDER", os.path.expanduser("~/.syncserver"))
    if not os.path.exists(folder):
        print("creating", folder)
        os.mkdir(folder)
    return folder


def col_path():
    return os.path.join(folder(), "collection.server.anki2")


def serve():
    global col

    col = Collection(col_path(), server=True)
    # don't hold an outer transaction open
    col.db.rollback()
    host = os.getenv("HOST", "0.0.0.0")
    port = int(os.getenv("PORT", "8080"))

    server = create_server(
        app,
        host=host,
        port=port,
        clear_untrusted_proxy_headers=True,
    )

    effective_port = server.effective_port  # type: ignore
    print(f"Sync server listening on http://{host}:{effective_port}/sync/")
    if host == "0.0.0.0":
        ip = socket.gethostbyname(socket.gethostname())
        print(f"Replace 0.0.0.0 with your machine's IP address (perhaps {ip})")
    print(
        "For more info, see https://github.com/ankitects/anki/blob/master/docs/syncserver.md"
    )
    server.run()