lsp_server.py

# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License.
"""Implementation of tool support over LSP."""
from __future__ import annotations

import copy
import json
import os
import pathlib
import re
import sys
import traceback
from typing import Any, Callable, Dict, List, Optional, Sequence, Union


# **********************************************************
# Update sys.path before importing any bundled libraries.
# **********************************************************
def update_sys_path(path_to_add: str, strategy: str) -> None:
    """Add given path to `sys.path`."""
    if path_to_add not in sys.path and os.path.isdir(path_to_add):
        if strategy == "useBundled":
            sys.path.insert(0, path_to_add)
        else:
            sys.path.append(path_to_add)


# Ensure that we can import LSP libraries, and other bundled libraries.
update_sys_path(
    os.fspath(pathlib.Path(__file__).parent.parent / "libs"),
    os.getenv("LS_IMPORT_STRATEGY", "useBundled"),
)

# **********************************************************
# Imports needed for the language server goes below this.
# **********************************************************
import lsp_jsonrpc as jsonrpc
import lsp_utils as utils
from lsprotocol import types as lsp
from pygls import server, uris, workspace

WORKSPACE_SETTINGS = {}
GLOBAL_SETTINGS = {}
RUNNER = pathlib.Path(__file__).parent / "lsp_runner.py"

MAX_WORKERS = 5
LSP_SERVER = server.LanguageServer(
    name="flake8-server", version="v0.1.0", max_workers=MAX_WORKERS
)


# **********************************************************
# Tool specific code goes below this.
# **********************************************************
TOOL_MODULE = "flake8"
TOOL_DISPLAY = "Flake8"

# Default arguments always passed to flake8.
TOOL_ARGS = ["--format='%(row)d,%(col)d,%(code).1s,%(code)s:%(text)s'"]

# Minimum version of flake8 supported.
MIN_VERSION = "5.0.0"

# **********************************************************
# Linting features start here
# **********************************************************


@LSP_SERVER.feature(lsp.TEXT_DOCUMENT_DID_OPEN)
def did_open(params: lsp.DidOpenTextDocumentParams) -> None:
    """LSP handler for textDocument/didOpen request."""
    document = LSP_SERVER.workspace.get_document(params.text_document.uri)
    diagnostics: list[lsp.Diagnostic] = _linting_helper(document)
    LSP_SERVER.publish_diagnostics(document.uri, diagnostics)


@LSP_SERVER.feature(lsp.TEXT_DOCUMENT_DID_SAVE)
def did_save(params: lsp.DidSaveTextDocumentParams) -> None:
    """LSP handler for textDocument/didSave request."""
    document = LSP_SERVER.workspace.get_document(params.text_document.uri)
    diagnostics: list[lsp.Diagnostic] = _linting_helper(document)
    LSP_SERVER.publish_diagnostics(document.uri, diagnostics)


@LSP_SERVER.feature(lsp.TEXT_DOCUMENT_DID_CLOSE)
def did_close(params: lsp.DidCloseTextDocumentParams) -> None:
    """LSP handler for textDocument/didClose request."""
    document = LSP_SERVER.workspace.get_document(params.text_document.uri)
    # Publishing empty diagnostics to clear the entries for this file.
    LSP_SERVER.publish_diagnostics(document.uri, [])


def _is_supported_file(document: workspace.Document) -> bool:
    """Checks if the given document is supported by this tool."""
    if document.path:
        file_path = pathlib.Path(document.path)
        return file_path.exists()

    return False


def _linting_helper(document: workspace.Document) -> list[lsp.Diagnostic]:
    try:
        if not _is_supported_file(document):
            log_always(f"Skipping linting for {document.uri} skipped: not supported")
            return []

        result = _run_tool_on_document(document, use_stdin=False)
        if result and result.stdout:
            log_to_output(f"{document.uri} :\r\n{result.stdout}")

            # deep copy here to prevent accidentally updating global settings.
            settings = copy.deepcopy(_get_settings_by_document(document))
            return _parse_output_using_regex(
                result.stdout, severity=settings["severity"]
            )
    except Exception:
        LSP_SERVER.show_message_log(
            f"Linting failed with error:\r\n{traceback.format_exc()}",
            lsp.MessageType.Error,
        )
    return []


def _get_severity(
    code: str, code_type: str, severity: Dict[str, str]
) -> lsp.DiagnosticSeverity:
    """Converts severity provided by linter to LSP specific value."""
    value = severity.get(code, None) or severity.get(code_type, "Error")
    try:
        return lsp.DiagnosticSeverity[value]
    except KeyError:
        pass

    return lsp.DiagnosticSeverity.Error


DIAGNOSTIC_RE = re.compile(
    r"(?P<line>\d+),(?P<column>-?\d+),(?P<type>\w+),(?P<code>\w+\d+):(?P<message>[^\r\n]*)"
)


def _parse_output_using_regex(
    content: str, severity: Dict[str, str]
) -> list[lsp.Diagnostic]:
    lines: list[str] = content.splitlines()
    diagnostics: list[lsp.Diagnostic] = []

    line_at_1 = True
    column_at_1 = True

    line_offset = 1 if line_at_1 else 0
    col_offset = 1 if column_at_1 else 0
    for line in lines:
        if line.startswith("'") and line.endswith("'"):
            line = line[1:-1]
        match = DIAGNOSTIC_RE.match(line)
        if match:
            data = match.groupdict()
            position = lsp.Position(
                line=max([int(data["line"]) - line_offset, 0]),
                character=max([int(data["column"]) - col_offset, 0]),
            )
            diagnostic = lsp.Diagnostic(
                range=lsp.Range(
                    start=position,
                    end=position,
                ),
                message=data.get("message"),
                severity=_get_severity(data["code"], data["type"], severity),
                code=data["code"],
                source=TOOL_DISPLAY,
            )
            diagnostics.append(diagnostic)

    return diagnostics


# **********************************************************
# Linting features end here
# **********************************************************


# **********************************************************
# Code Action features start here
# **********************************************************
class QuickFixSolutions:
    """Manages quick fixes registered using the quick fix decorator."""

    def __init__(self):
        self._solutions: Dict[
            str,
            Callable[[workspace.Document, List[lsp.Diagnostic]], List[lsp.CodeAction]],
        ] = {}

    def quick_fix(
        self,
        codes: Union[str, List[str]],
    ):
        """Decorator used for registering quick fixes."""

        def decorator(
            func: Callable[
                [workspace.Document, List[lsp.Diagnostic]], List[lsp.CodeAction]
            ]
        ):
            if isinstance(codes, str):
                if codes in self._solutions:
                    raise utils.QuickFixRegistrationError(codes)
                self._solutions[codes] = func
            else:
                for code in codes:
                    if code in self._solutions:
                        raise utils.QuickFixRegistrationError(code)
                    self._solutions[code] = func

        return decorator

    def solutions(
        self, code: str
    ) -> Optional[
        Callable[[workspace.Document, List[lsp.Diagnostic]], List[lsp.CodeAction]]
    ]:
        """Given a flake8 error code returns a function, if available, that provides
        quick fix code actions."""

        try:
            return self._solutions[code]
        except KeyError:
            return None


QUICK_FIXES = QuickFixSolutions()


@LSP_SERVER.feature(
    lsp.TEXT_DOCUMENT_CODE_ACTION,
    lsp.CodeActionOptions(code_action_kinds=[lsp.CodeActionKind.QuickFix]),
)
def code_action(params: lsp.CodeActionParams) -> List[lsp.CodeAction]:
    """LSP handler for textDocument/codeAction request."""
    diagnostics = list(
        d for d in params.context.diagnostics if d.source == TOOL_DISPLAY
    )

    document = LSP_SERVER.workspace.get_document(params.text_document.uri)

    code_actions = []
    for diagnostic in diagnostics:
        func = QUICK_FIXES.solutions(diagnostic.code)
        if func:
            code_actions.extend(func(document, [diagnostic]))

    return code_actions


@QUICK_FIXES.quick_fix(codes=["E241", "E242", "E271", "E272", "E273", "E274", "E275"])
def fix_format(
    _document: workspace.Document, diagnostics: List[lsp.Diagnostic]
) -> List[lsp.CodeAction]:
    """Provides quick fixes which involve formatting document."""
    return [
        _command_quick_fix(
            diagnostics=diagnostics,
            title=f"{TOOL_DISPLAY}: Run document formatting",
            command="editor.action.formatDocument",
        )
    ]


def _command_quick_fix(
    diagnostics: List[lsp.Diagnostic],
    title: str,
    command: str,
    args: Optional[List[Any]] = None,
) -> lsp.CodeAction:
    return lsp.CodeAction(
        title=title,
        kind=lsp.CodeActionKind.QuickFix,
        diagnostics=diagnostics,
        command=lsp.Command(title=title, command=command, arguments=args),
    )


def _create_workspace_edits(
    document: workspace.Document, results: Optional[List[lsp.TextEdit]]
):
    return lsp.WorkspaceEdit(
        document_changes=[
            lsp.TextDocumentEdit(
                text_document=lsp.OptionalVersionedTextDocumentIdentifier(
                    uri=document.uri,
                    version=document.version,
                ),
                edits=results,
            )
        ],
    )


# **********************************************************
# Code Action features end here
# **********************************************************


# **********************************************************
# Required Language Server Initialization and Exit handlers.
# **********************************************************
@LSP_SERVER.feature(lsp.INITIALIZE)
def initialize(params: lsp.InitializeParams) -> None:
    """LSP handler for initialize request."""
    log_to_output(f"CWD Server: {os.getcwd()}")

    paths = "\r\n   ".join(sys.path)
    log_to_output(f"sys.path used to run Server:\r\n   {paths}")

    GLOBAL_SETTINGS.update(**params.initialization_options.get("globalSettings", {}))

    settings = params.initialization_options["settings"]
    _update_workspace_settings(settings)
    log_to_output(
        f"Settings used to run Server:\r\n{json.dumps(settings, indent=4, ensure_ascii=False)}\r\n"
    )
    log_to_output(
        f"Global settings:\r\n{json.dumps(GLOBAL_SETTINGS, indent=4, ensure_ascii=False)}\r\n"
    )

    _log_version_info()


@LSP_SERVER.feature(lsp.EXIT)
def on_exit(_params: Optional[Any] = None) -> None:
    """Handle clean up on exit."""
    jsonrpc.shutdown_json_rpc()


@LSP_SERVER.feature(lsp.SHUTDOWN)
def on_shutdown(_params: Optional[Any] = None) -> None:
    """Handle clean up on shutdown."""
    jsonrpc.shutdown_json_rpc()


def _log_version_info() -> None:
    for value in WORKSPACE_SETTINGS.values():
        try:
            from packaging.version import parse as parse_version

            settings = copy.deepcopy(value)
            result = _run_tool(["--version"], settings)
            code_workspace = settings["workspaceFS"]
            log_to_output(
                f"Version info for linter running for {code_workspace}:\r\n{result.stdout}"
            )

            # This is text we get from running `flake8 --version`
            # Example:
            # 5.0.4 (mccabe: 0.7.0, pycodestyle: 2.9.1, pyflakes: 2.5.0) CPython 3.7.7
            # ^---^---- this is the version info we want
            first_line = result.stdout.splitlines(keepends=False)[0]
            actual_version = first_line.split(" ")[0]

            version = parse_version(actual_version)
            min_version = parse_version(MIN_VERSION)

            if version < min_version:
                log_error(
                    f"Version of linter running for {code_workspace} is NOT supported:\r\n"
                    f"SUPPORTED {TOOL_MODULE}>={min_version}\r\n"
                    f"FOUND {TOOL_MODULE}=={actual_version}\r\n"
                )
            else:
                log_to_output(
                    f"SUPPORTED {TOOL_MODULE}>={min_version}\r\n"
                    f"FOUND {TOOL_MODULE}=={actual_version}\r\n"
                )
        except:  # noqa: E722
            log_to_output(
                f"Error while detecting flake8 version:\r\n{traceback.format_exc()}"
            )


# *****************************************************
# Internal functional and settings management APIs.
# *****************************************************
def _get_global_defaults():
    return {
        "path": GLOBAL_SETTINGS.get("path", []),
        "interpreter": GLOBAL_SETTINGS.get("interpreter", [sys.executable]),
        "args": GLOBAL_SETTINGS.get("args", []),
        "severity": GLOBAL_SETTINGS.get(
            "severity",
            {
                "E": "Error",
                "F": "Error",
                "I": "Information",
                "W": "Warning",
            },
        ),
        "importStrategy": GLOBAL_SETTINGS.get("importStrategy", "useBundled"),
        "showNotifications": GLOBAL_SETTINGS.get("showNotifications", "off"),
    }


def _update_workspace_settings(settings):
    if not settings:
        key = utils.normalize_path(GLOBAL_SETTINGS.get("cwd", os.getcwd()))
        WORKSPACE_SETTINGS[key] = {
            "cwd": key,
            "workspaceFS": key,
            "workspace": uris.from_fs_path(key),
            **_get_global_defaults(),
        }
        return

    for setting in settings:
        key = utils.normalize_path(uris.to_fs_path(setting["workspace"]))
        WORKSPACE_SETTINGS[key] = {
            **setting,
            "workspaceFS": key,
        }


def _get_document_key(document: workspace.Document):
    if WORKSPACE_SETTINGS:
        document_workspace = pathlib.Path(document.path)
        workspaces = {s["workspaceFS"] for s in WORKSPACE_SETTINGS.values()}

        # Find workspace settings for the given file.
        while document_workspace != document_workspace.parent:
            norm_path = utils.normalize_path(document_workspace)
            if norm_path in workspaces:
                return norm_path
            document_workspace = document_workspace.parent

    return None


def _get_settings_by_document(document: workspace.Document | None):
    if document is None or document.path is None:
        return list(WORKSPACE_SETTINGS.values())[0]

    key = _get_document_key(document)
    if key is None:
        # This is either a non-workspace file or there is no workspace.
        key = utils.normalize_path(pathlib.Path(document.path).parent)
        return {
            "cwd": key,
            "workspaceFS": key,
            "workspace": uris.from_fs_path(key),
            **_get_global_defaults(),
        }

    return WORKSPACE_SETTINGS[str(key)]


# *****************************************************
# Internal execution APIs.
# *****************************************************
def _run_tool_on_document(
    document: workspace.Document,
    use_stdin: bool = False,
    extra_args: Sequence[str] = [],
) -> utils.RunResult | None:
    """Runs tool on the given document.

    if use_stdin is true then contents of the document is passed to the
    tool via stdin.
    """
    if str(document.uri).startswith("vscode-notebook-cell"):
        log_warning(f"Skipping notebook cells [Not Supported]: {str(document.uri)}")
        return None

    if utils.is_stdlib_file(document.path):
        log_warning(f"Skipping standard library file: {document.path}")
        return None

    # deep copy here to prevent accidentally updating global settings.
    settings = copy.deepcopy(_get_settings_by_document(document))

    code_workspace = settings["workspaceFS"]
    cwd = settings["cwd"]

    use_path = False
    use_rpc = False
    if settings["path"]:
        # 'path' setting takes priority over everything.
        use_path = True
        argv = settings["path"]
    elif settings["interpreter"] and not utils.is_current_interpreter(
        settings["interpreter"][0]
    ):
        # If there is a different interpreter set use JSON-RPC to the subprocess
        # running under that interpreter.
        argv = [TOOL_MODULE]
        use_rpc = True
    else:
        # if the interpreter is same as the interpreter running this
        # process then run as module.
        argv = [TOOL_MODULE]

    argv += TOOL_ARGS + settings["args"] + extra_args

    if use_stdin:
        argv += ["--stdin-display-name", document.path, "-"]
    else:
        argv += [document.path]

    if use_path:
        # This mode is used when running executables.
        log_to_output(" ".join(argv))
        log_to_output(f"CWD Server: {cwd}")
        result = utils.run_path(
            argv=argv,
            use_stdin=use_stdin,
            cwd=cwd,
            source=document.source.replace("\r\n", "\n"),
        )
        if result.stderr:
            log_to_output(result.stderr)
    elif use_rpc:
        # This mode is used if the interpreter running this server is different from
        # the interpreter used for running this server.
        log_to_output(" ".join(settings["interpreter"] + ["-m"] + argv))
        log_to_output(f"CWD Linter: {cwd}")

        result = jsonrpc.run_over_json_rpc(
            workspace=code_workspace,
            interpreter=settings["interpreter"],
            module=TOOL_MODULE,
            argv=argv,
            use_stdin=use_stdin,
            cwd=cwd,
            source=document.source,
        )
        result = _to_run_result_with_logging(result)
    else:
        # In this mode the tool is run as a module in the same process as the language server.
        log_to_output(" ".join([sys.executable, "-m"] + argv))
        log_to_output(f"CWD Linter: {cwd}")
        # This is needed to preserve sys.path, in cases where the tool modifies
        # sys.path and that might not work for this scenario next time around.
        with utils.substitute_attr(sys, "path", [""] + sys.path[:]):
            try:
                result = utils.run_module(
                    module=TOOL_MODULE,
                    argv=argv,
                    use_stdin=use_stdin,
                    cwd=cwd,
                    source=document.source,
                )
            except Exception:
                log_error(traceback.format_exc(chain=True))
                raise
        if result.stderr:
            log_to_output(result.stderr)

    return result


def _run_tool(extra_args: Sequence[str], settings: Dict[str, Any]) -> utils.RunResult:
    """Runs tool."""
    code_workspace = settings["workspaceFS"]
    cwd = settings["cwd"]

    use_path = False
    use_rpc = False
    if len(settings["path"]) > 0:
        # 'path' setting takes priority over everything.
        use_path = True
        argv = settings["path"]
    elif len(settings["interpreter"]) > 0 and not utils.is_current_interpreter(
        settings["interpreter"][0]
    ):
        # If there is a different interpreter set use JSON-RPC to the subprocess
        # running under that interpreter.
        argv = [TOOL_MODULE]
        use_rpc = True
    else:
        # if the interpreter is same as the interpreter running this
        # process then run as module.
        argv = [TOOL_MODULE]

    argv += extra_args

    if use_path:
        # This mode is used when running executables.
        log_to_output(" ".join(argv))
        log_to_output(f"CWD Server: {cwd}")
        result = utils.run_path(argv=argv, use_stdin=True, cwd=cwd)
        if result.stderr:
            log_to_output(result.stderr)
    elif use_rpc:
        # This mode is used if the interpreter running this server is different from
        # the interpreter used for running this server.
        log_to_output(" ".join(settings["interpreter"] + ["-m"] + argv))
        log_to_output(f"CWD Linter: {cwd}")
        result = jsonrpc.run_over_json_rpc(
            workspace=code_workspace,
            interpreter=settings["interpreter"],
            module=TOOL_MODULE,
            argv=argv,
            use_stdin=True,
            cwd=cwd,
        )
        result = _to_run_result_with_logging(result)
    else:
        # In this mode the tool is run as a module in the same process as the language server.
        log_to_output(" ".join([sys.executable, "-m"] + argv))
        log_to_output(f"CWD Linter: {cwd}")
        # This is needed to preserve sys.path, in cases where the tool modifies
        # sys.path and that might not work for this scenario next time around.
        with utils.substitute_attr(sys, "path", [""] + sys.path[:]):
            try:
                result = utils.run_module(
                    module=TOOL_MODULE, argv=argv, use_stdin=True, cwd=cwd
                )
            except Exception:
                log_error(traceback.format_exc(chain=True))
                raise
        if result.stderr:
            log_to_output(result.stderr)

    log_to_output(f"\r\n{result.stdout}\r\n")
    return result


def _to_run_result_with_logging(rpc_result: jsonrpc.RpcRunResult) -> utils.RunResult:
    error = ""
    if rpc_result.exception:
        log_error(rpc_result.exception)
        error = rpc_result.exception
    elif rpc_result.stderr:
        log_to_output(rpc_result.stderr)
        error = rpc_result.stderr
    return utils.RunResult(rpc_result.stdout, error)


# *****************************************************
# Logging and notification.
# *****************************************************
def log_to_output(
    message: str, msg_type: lsp.MessageType = lsp.MessageType.Log
) -> None:
    """Logs messages to Output > Flake8 channel only."""
    LSP_SERVER.show_message_log(message, msg_type)


def log_error(message: str) -> None:
    """Logs messages with notification on error."""
    LSP_SERVER.show_message_log(message, lsp.MessageType.Error)
    if os.getenv("LS_SHOW_NOTIFICATION", "off") in ["onError", "onWarning", "always"]:
        LSP_SERVER.show_message(message, lsp.MessageType.Error)


def log_warning(message: str) -> None:
    """Logs messages with notification on warning."""
    LSP_SERVER.show_message_log(message, lsp.MessageType.Warning)
    if os.getenv("LS_SHOW_NOTIFICATION", "off") in ["onWarning", "always"]:
        LSP_SERVER.show_message(message, lsp.MessageType.Warning)


def log_always(message: str) -> None:
    """Logs messages with notification."""
    LSP_SERVER.show_message_log(message, lsp.MessageType.Info)
    if os.getenv("LS_SHOW_NOTIFICATION", "off") in ["always"]:
        LSP_SERVER.show_message(message, lsp.MessageType.Info)


# *****************************************************
# Start the server.
# *****************************************************
if __name__ == "__main__":
    LSP_SERVER.start_io()