# Copyright 2019 Novartis Institutes for BioMedical Research Inc. Licensed
# under the Apache License, Version 2.0 (the "License"); you may not use
# this file except in compliance with the License. You may obtain a copy
# of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless
# required by applicable law or agreed to in writing, software distributed
# under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
# OR CONDITIONS OF ANY KIND, either express or implied. See the License for
# the specific language governing permissions and limitations under the License.
# import BaseHTTPServer
import json
import logging
import os
import urllib.parse
from threading import Lock, Thread

from flask import (
    Flask,
    make_response,
    redirect,
    render_template,
    request,
    send_from_directory,
    url_for,
)
from werkzeug.middleware.proxy_fix import ProxyFix

from cellxgene_gateway import env, flask_util
from cellxgene_gateway.backend_cache import BackendCache
from cellxgene_gateway.cache_entry import CacheEntryStatus
from cellxgene_gateway.cache_key import CacheKey
from cellxgene_gateway.cellxgene_exception import CellxgeneException
from cellxgene_gateway.extra_scripts import get_extra_scripts
from cellxgene_gateway.filecrawl import render_item_source
from cellxgene_gateway.process_exception import ProcessException
from cellxgene_gateway.prune_process_cache import PruneProcessCache
from cellxgene_gateway.util import current_time_stamp

app = Flask(__name__)

item_sources = []
default_item_source = None

# Guard for lazy initialization so tests can import this module without
# triggering environment-dependent side effects. initialize_data_sources()
# will set this to True when it has run.
data_sources_initialized = False
data_sources_init_lock = Lock()


def _force_https(app):
    def wrapper(environ, start_response):
        if env.external_protocol is not None:
            environ["wsgi.url_scheme"] = env.external_protocol
        return app(environ, start_response)

    return wrapper


def set_no_cache(resp):
    resp.headers["Cache-Control"] = "no-cache, no-store, must-revalidate"
    resp.headers["Pragma"] = "no-cache"
    resp.headers["Expires"] = "0"
    resp.headers["Cache-Control"] = "public, max-age=0"
    return resp


app.wsgi_app = _force_https(app.wsgi_app)
if (
    env.proxy_fix_for > 0
    or env.proxy_fix_proto > 0
    or env.proxy_fix_host > 0
    or env.proxy_fix_port > 0
    or env.proxy_fix_prefix > 0
):
    app.wsgi_app = ProxyFix(
        app.wsgi_app,
        x_for=env.proxy_fix_for,
        x_proto=env.proxy_fix_proto,
        x_host=env.proxy_fix_host,
        x_port=env.proxy_fix_port,
        x_prefix=env.proxy_fix_prefix,
    )


# WSGI middleware to ensure data sources are initialized before the first
# WSGI request is handled. This guarantees initialization works under
# Gunicorn/uWSGI (which import the module but don't call main()). The
# initialize_data_sources() function is idempotent-protected by
# data_sources_initialized and data_sources_init_lock.
def _init_on_first_wsgi_request(wsgi_app):
    def middleware(environ, start_response):
        global data_sources_initialized
        if not data_sources_initialized:
            with data_sources_init_lock:
                if not app.extensions.get("cellxgene_gateway", {}).get("launchtime"):
                    app.extensions.setdefault("cellxgene_gateway", {})[
                        "launchtime"
                    ] = current_time_stamp()

                if not data_sources_initialized:
                    initialize_data_sources()

                    env.validate()
                    if not item_sources or not len(item_sources):
                        raise Exception(
                            "No data sources specified for Cellxgene Gateway"
                        )

                    global default_item_source
                    if default_item_source is None:
                        default_item_source = item_sources[0]

                    data_sources_initialized = True
        return wsgi_app(environ, start_response)

    return middleware


# Wrap the WSGI app so Gunicorn/uWSGI will trigger initialization when the
# first request comes in. Tests that need initialization can call
# initialize_data_sources() directly.
app.wsgi_app = _init_on_first_wsgi_request(app.wsgi_app)

cache = BackendCache()


# Initialize data sources - this is defined later in the file but called here
# to ensure initialization happens when WSGI servers (Gunicorn) import the module
def initialize_data_sources():
    """Initialize data sources from environment variables.
    Called at module import time for WSGI server compatibility (Gunicorn).
    Uses a guard flag to prevent double initialization within a process."""
    global default_item_source

    logging.basicConfig(
        level=env.log_level,
        format="%(asctime)s:%(name)s:%(levelname)s:%(message)s",
    )
    logger = logging.getLogger(__name__)

    cellxgene_data = os.environ.get("CELLXGENE_DATA", None)
    cellxgene_bucket = os.environ.get("CELLXGENE_BUCKET", None)

    if cellxgene_bucket is not None:
        from cellxgene_gateway.items.s3.s3item_source import S3ItemSource

        s3_source = S3ItemSource(cellxgene_bucket, name="s3")
        item_sources.append(s3_source)
        default_item_source = s3_source
        logger.info("Initialized S3 data source")
        logger.debug(f"S3 bucket: {cellxgene_bucket}")
    if cellxgene_data is not None:
        from cellxgene_gateway.items.file.fileitem_source import FileItemSource

        file_source = FileItemSource(cellxgene_data, name="local")
        item_sources.append(file_source)
        default_item_source = file_source
        logger.info("Initialized local file data source")
        logger.debug(f"Data directory: {cellxgene_data}")
    if len(item_sources) == 0:
        raise Exception("Please specify CELLXGENE_DATA or CELLXGENE_BUCKET")
    flask_util.include_source_in_url = len(item_sources) > 1


@app.errorhandler(CellxgeneException)
def handle_invalid_usage(error):
    message = f"{error.http_status} Error : {error.message}"

    return (
        render_template(
            "cellxgene_error.html",
            extra_scripts=get_extra_scripts(),
            message=message,
        ),
        error.http_status,
    )


@app.errorhandler(ProcessException)
def handle_invalid_process(error):
    message = []

    message.append(error.message)
    message.append(f"{error.http_status} Error.")
    message.append(f"Stdout: {error.stdout}")
    message.append(f"Stderr: {error.stderr}")

    return (
        render_template(
            "process_error.html",
            extra_scripts=get_extra_scripts(),
            message=error.message,
            http_status=error.http_status,
            stdout=error.stdout,
            stderr=error.stderr,
            relaunch_url=error.key.relaunch_url(),
            annotation_file=error.key.annotation_descriptor,
        ),
        error.http_status,
    )


@app.route("/favicon.ico")
def favicon():
    return send_from_directory(
        os.path.join(app.root_path, "static"),
        "nibr.ico",
        mimetype="image/vnd.microsof.icon",
    )


@app.route("/")
def index():
    return render_template(
        "index.html",
        ip=env.ip,
        cellxgene_data=env.cellxgene_data,
        extra_scripts=get_extra_scripts(),
    )


@app.route("/filecrawl.html")
@app.route("/filecrawl/<path:path>")
def filecrawl(path=None):
    source_name = request.args.get("source")
    sources = (
        filter(
            lambda x: x.name == urllib.parse.unquote_plus(source_name),
            item_sources,
        )
        if source_name
        else item_sources
    )
    # loop all data sources --
    rendered_sources = [
        render_item_source(item_source, path) for item_source in sources
    ]  # will we need to make this async in the page???
    rendered_html = "\n".join(rendered_sources)

    resp = make_response(
        render_template(
            "filecrawl.html",
            extra_scripts=get_extra_scripts(),
            rendered_html=rendered_html,
            path=path,
        )
    )
    set_no_cache(resp)
    return resp


entry_lock = Lock()


def matching_source(source_name):
    if source_name is None and default_item_source is not None:
        source_name = default_item_source.name
    matching = [i for i in item_sources if i.name == source_name]
    if len(matching) != 1:
        raise Exception(f"Could not find matching item source {source_name}")
    source = matching[0]
    return source


@app.route(
    "/source/<path:source_name>/view/<path:path>",
    methods=["GET", "PUT", "POST"],
)
@app.route("/view/<path:path>", methods=["GET", "PUT", "POST"])
def do_view(path, source_name=None):
    source = matching_source(source_name)
    match = cache.check_path(source, path)

    if match is None:
        lookup = source.lookup(path)
        if lookup is None:
            raise CellxgeneException(
                f"Could not find item for path {path} in source {source.name}",
                404,
            )
        key = CacheKey.for_lookup(source, lookup)
        print(
            f"view path={path}, source_name={source_name}, dataset={key.file_path}, annotation_file= {key.annotation_file_path}, key={key.descriptor}, source={key.source_name}"
        )
        with entry_lock:
            match = cache.check_entry(key)
            if match is None:
                uascripts = get_extra_scripts()
                match = cache.create_entry(key, uascripts)

    match.timestamp = current_time_stamp()

    if (
        match.status == CacheEntryStatus.loaded
        or match.status == CacheEntryStatus.loading
    ):
        if source.is_authorized(match.key.descriptor):
            return match.serve_content(path)
        else:
            raise CellxgeneException("User not authorized to access this data", 403)
    elif match.status == CacheEntryStatus.error:
        raise ProcessException.from_cache_entry(match)
    else:
        raise CellxgeneException(
            f"Unexpected cache entry status {match.status} for key {match.key.descriptor}",
            500,
        )


@app.route("/cache_status", methods=["GET"])
def do_GET_status():
    return render_template(
        "cache_status.html",
        entry_list=cache.entry_list,
        extra_scripts=get_extra_scripts(),
    )


@app.route("/cache_status.json", methods=["GET"])
def do_GET_status_json():
    def map_entry(entry):
        dataset = entry.key.h5ad_item.descriptor
        annotation_file = entry.key.annotation_descriptor
        return {
            "dataset": dataset,
            "annotation_file": annotation_file,
            "launchtime": entry.launchtime,
            "last_access": entry.timestamp,
            "status": entry.status.name,
        }

    return json.dumps(
        {
            "launchtime": app.extensions.get("cellxgene_gateway", {}).get("launchtime"),
            "entry_list": [map_entry(entry) for entry in cache.entry_list],
        }
    )


def get_cache_key(path):
    if request.args.get("source_name"):
        source_name = request.args.get("source_name")
    elif default_item_source:
        source_name = default_item_source.name
    else:
        source_name = None
    source = matching_source(source_name)
    key = CacheKey.for_lookup(source, source.lookup(path))
    return key


@app.route("/relaunch/<path:path>", methods=["GET"])
def do_relaunch(path):
    key = get_cache_key(path)
    match = cache.check_entry(key)
    if not match is None:
        match.terminate()
    return redirect(
        key.view_url,
        code=302,
    )


@app.route("/terminate/<path:path>", methods=["GET"])
def do_terminate(path):
    key = get_cache_key(path)
    match = cache.check_entry(key)
    if not match is None:
        match.terminate()
    return redirect(url_for("do_GET_status"), code=302)


@app.route("/metadata/ip_address", methods=["GET"])
def ip_address():
    resp = make_response(env.ip)
    return set_no_cache(resp)


def start_pruner_thread():
    pruner = PruneProcessCache(cache)
    # Run the pruner as a daemon thread so it won't block interpreter
    # shutdown (for example when Ctrl-C is used in the main thread).
    # This avoids "Exception ignored in: <module 'threading'...>" at exit.
    background_thread = Thread(target=pruner, daemon=True)
    background_thread.start()


def launch():
    start_pruner_thread()

    app.extensions.setdefault("cellxgene_gateway", {})[
        "launchtime"
    ] = current_time_stamp()
    app.run(host="0.0.0.0", port=env.gateway_port, debug=False)


app.extensions.setdefault("cellxgene_gateway", {})["launchtime"] = None


def main():
    """CLI entry point for Flask development server."""
    launch()


if __name__ == "__main__":
    main()