# Copyright (c) Meta Platforms, Inc. and affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.


"""
This is an implementation of Pysa's language server. It is a refactored
version of the server run by `pyre persistent`.
"""

import asyncio
import json
import logging
from typing import Union

from .. import (
    command_arguments,
    configuration as configuration_module,
    frontend_configuration,
    json_rpc,
    log,
    log_lsp_event,
)
from ..language_server import connections, protocol as lsp
from . import commands, start
from .initialization import (
    InitializationExit,
    InitializationFailure,
    InitializationSuccess,
)
from .persistent import process_initialize_request

from .pyre_language_server import _wait_for_exit, read_lsp_request

LOG: logging.Logger = logging.getLogger(__name__)


async def try_initialize(
    input_channel: connections.AsyncTextReader,
    output_channel: connections.AsyncTextWriter,
) -> Union[InitializationSuccess, InitializationFailure, InitializationExit]:
    """
    Read an LSP message from the input channel and try to initialize an LSP
    server. Also write to the output channel with proper response if the input
    message is a request instead of a notification.

    The function can return one of three possibilities:
    - If the initialization succeeds, return `InitializationSuccess`.
    - If the initialization fails, return `InitializationFailure`. There could
      be many reasons for the failure: The incoming LSP message may not be an
      initiailization request. The incoming LSP request may be malformed. Or the
      client may not complete the handshake by sending back an `initialized` request.
    - If an exit notification is received, return `InitializationExit`. The LSP
      spec allows exiting a server without a preceding initialize request.
    """
    request = None
    try:
        request = await lsp.read_json_rpc(input_channel)
        LOG.debug(f"Received pre-initialization LSP request: {request}")

        request_id = request.id
        if request_id is None:
            return (
                InitializationExit()
                if request.method == "exit"
                else InitializationFailure()
            )
        if request.method != "initialize":
            raise lsp.ServerNotInitializedError("An initialize request is needed.")
        request_parameters = request.parameters
        if request_parameters is None:
            raise lsp.ServerNotInitializedError(
                "Missing parameters for initialize request."
            )

        initialize_parameters = lsp.InitializeParameters.from_json_rpc_parameters(
            request_parameters
        )
        result = process_initialize_request(initialize_parameters)
        await lsp.write_json_rpc(
            output_channel,
            json_rpc.SuccessResponse(id=request_id, result=result.to_dict()),
        )

        initialized_notification = await lsp.read_json_rpc(input_channel)
        if initialized_notification.method == "shutdown":
            await _wait_for_exit(input_channel, output_channel)
            return InitializationExit()
        elif initialized_notification.method != "initialized":
            actual_message = json.dumps(initialized_notification.json())
            raise lsp.ServerNotInitializedError(
                "Failed to receive an `initialized` request from client. "
                + f"Got {log.truncate(actual_message, 100)}"
            )

        return InitializationSuccess(
            client_capabilities=initialize_parameters.capabilities,
            client_info=initialize_parameters.client_info,
            initialization_options=initialize_parameters.initialization_options,
        )
    except json_rpc.JSONRPCException as json_rpc_error:
        await lsp.write_json_rpc(
            output_channel,
            json_rpc.ErrorResponse(
                id=request.id if request is not None else None,
                code=json_rpc_error.error_code(),
                message=str(json_rpc_error),
                data={"retry": False},
            ),
        )
        return InitializationFailure(exception=json_rpc_error)


class PysaServer:
    # I/O Channels
    input_channel: connections.AsyncTextReader
    output_channel: connections.AsyncTextWriter

    # Immutable States
    client_capabilities: lsp.ClientCapabilities

    def __init__(
        self,
        input_channel: connections.AsyncTextReader,
        output_channel: connections.AsyncTextWriter,
        client_capabilities: lsp.ClientCapabilities,
        pyre_arguments: start.Arguments,
        binary_location: str,
        project_identifier: str,
    ) -> None:
        self.input_channel = input_channel
        self.output_channel = output_channel
        self.client_capabilities = client_capabilities
        self.pyre_arguments = pyre_arguments
        self.binary_location = binary_location
        self.project_identifier = project_identifier

    async def show_message_to_client(
        self, message: str, level: lsp.MessageType = lsp.MessageType.INFO
    ) -> None:
        await lsp.write_json_rpc(
            self.output_channel,
            json_rpc.Request(
                method="window/showMessage",
                parameters=json_rpc.ByNameParameters(
                    {"type": int(level), "message": message}
                ),
            ),
        )

    async def log_and_show_message_to_client(
        self, message: str, level: lsp.MessageType = lsp.MessageType.INFO
    ) -> None:
        if level == lsp.MessageType.ERROR:
            LOG.error(message)
        elif level == lsp.MessageType.WARNING:
            LOG.warning(message)
        elif level == lsp.MessageType.INFO:
            LOG.info(message)
        else:
            LOG.debug(message)
        await self.show_message_to_client(message, level)

    async def wait_for_exit(self) -> int:
        while True:
            request = await read_lsp_request(self.input_channel, self.output_channel)
            LOG.debug(f"Received post-shutdown request: {request}")

            if request.method == "exit":
                return 0
            else:
                raise json_rpc.InvalidRequestError("LSP server has been shut down")

    async def process_open_request(
        self, parameters: lsp.DidOpenTextDocumentParameters
    ) -> None:
        document_path = parameters.text_document.document_uri().to_file_path()
        if document_path is None:
            raise json_rpc.InvalidRequestError(
                f"Document URI is not a file: {parameters.text_document.uri}"
            )

    async def process_close_request(
        self, parameters: lsp.DidCloseTextDocumentParameters
    ) -> None:
        document_path = parameters.text_document.document_uri().to_file_path()
        if document_path is None:
            raise json_rpc.InvalidRequestError(
                f"Document URI is not a file: {parameters.text_document.uri}"
            )
        try:
            LOG.info(f"File closed: {document_path}")

        except KeyError:
            LOG.warning(f"Trying to close an un-opened file: {document_path}")

    async def process_did_save_request(
        self, parameters: lsp.DidSaveTextDocumentParameters
    ) -> None:
        document_path = parameters.text_document.document_uri().to_file_path()
        if document_path is None:
            raise json_rpc.InvalidRequestError(
                f"Document URI is not a file: {parameters.text_document.uri}"
            )

    async def run(self) -> int:
        while True:
            request = await read_lsp_request(self.input_channel, self.output_channel)

            try:
                if request.method == "exit":
                    return commands.ExitCode.FAILURE
                elif request.method == "shutdown":
                    await lsp.write_json_rpc(
                        self.output_channel,
                        json_rpc.SuccessResponse(id=request.id, result=None),
                    )
                    return await self.wait_for_exit()
                elif request.method == "textDocument/didOpen":
                    parameters = request.parameters
                    if parameters is None:
                        raise json_rpc.InvalidRequestError(
                            "Missing parameters for didOpen method"
                        )
                    await self.process_open_request(
                        lsp.DidOpenTextDocumentParameters.from_json_rpc_parameters(
                            parameters
                        )
                    )
                elif request.method == "textDocument/didClose":
                    parameters = request.parameters
                    if parameters is None:
                        raise json_rpc.InvalidRequestError(
                            "Missing parameters for didClose method"
                        )
                    await self.process_close_request(
                        lsp.DidCloseTextDocumentParameters.from_json_rpc_parameters(
                            parameters
                        )
                    )
                elif request.method == "textDocument/didSave":
                    parameters = request.parameters
                    if parameters is None:
                        raise json_rpc.InvalidRequestError(
                            "Missing parameters for didSave method"
                        )
                    await self.process_did_save_request(
                        lsp.DidSaveTextDocumentParameters.from_json_rpc_parameters(
                            parameters
                        )
                    )
                elif request.id is not None:
                    raise lsp.RequestCancelledError("Request not supported yet")
            except json_rpc.JSONRPCException as json_rpc_error:
                LOG.debug(
                    f"Exception occurred while processing request: {json_rpc_error}"
                )
                await lsp.write_json_rpc_ignore_connection_error(
                    self.output_channel,
                    json_rpc.ErrorResponse(
                        id=request.id,
                        activity_key=request.activity_key,
                        code=json_rpc_error.error_code(),
                        message=str(json_rpc_error),
                    ),
                )


async def run_persistent(
    binary_location: str, project_identifier: str, pysa_arguments: start.Arguments
) -> int:
    stdin, stdout = await connections.create_async_stdin_stdout()
    while True:
        initialize_result = await try_initialize(stdin, stdout)
        if isinstance(initialize_result, InitializationExit):
            LOG.info("Received exit request before initialization.")
            return 0
        elif isinstance(initialize_result, InitializationSuccess):
            LOG.info("Initialization successful.")
            client_info = initialize_result.client_info
            log_lsp_event.log(
                remote_logging=pysa_arguments.base_arguments.remote_logging,
                event=log_lsp_event.LSPEvent.INITIALIZED,
                normals=(
                    {}
                    if client_info is None
                    else {
                        "lsp client name": client_info.name,
                        "lsp client version": client_info.version,
                    }
                ),
            )

            client_capabilities = initialize_result.client_capabilities
            LOG.debug(f"Client capabilities: {client_capabilities}")
            server = PysaServer(
                input_channel=stdin,
                output_channel=stdout,
                client_capabilities=client_capabilities,
                binary_location=binary_location,
                project_identifier=project_identifier,
                pyre_arguments=pysa_arguments,
            )
            return await server.run()
        elif isinstance(initialize_result, InitializationFailure):
            exception = initialize_result.exception
            message = (
                str(exception) if exception is not None else "ignoring notification"
            )
            LOG.info(f"Initialization failed: {message}")
            # Loop until we get either InitializeExit or InitializeSuccess
        else:
            raise RuntimeError("Cannot determine the type of initialize_result")


def run(
    configuration: frontend_configuration.Base,
    start_arguments: command_arguments.StartArguments,
) -> int:
    binary_location = configuration.get_binary_location()
    if binary_location is None:
        raise configuration_module.InvalidConfiguration(
            "Cannot locate a Pyre binary to run."
        )

    project_identifier = configuration.get_project_identifier()
    pyre_arguments = start.create_server_arguments(configuration, start_arguments)
    if pyre_arguments.watchman_root is None:
        raise commands.ClientException(
            (
                "Cannot locate a `watchman` root. Pyre's server will not function "
                + "properly."
            )
        )

    return asyncio.get_event_loop().run_until_complete(
        run_persistent(str(binary_location), project_identifier, pyre_arguments)
    )
