"""Server registry — per-language LSP server definitions.

Each :class:`ServerDef` matches files (by extension or basename for
extensionless files like ``Dockerfile``), resolves a project root, and
assembles the spawn command.  Auto-installation lives in
:mod:`agent.lsp.install`; nothing here probes binaries until a file in
that language is actually edited.
"""
from __future__ import annotations

import logging
import os
import shutil
from dataclasses import dataclass, field
from typing import Any, Callable, Dict, List, Optional, Sequence, Tuple

from agent.lsp.workspace import nearest_root

logger = logging.getLogger("agent.lsp.servers")

# LSP languageId for ``textDocument/didOpen``, as language → extensions.  A few
# servers (typescript-language-server, vue-language-server) refuse wrong IDs.
_EXTS_BY_LANGUAGE: Dict[str, Sequence[str]] = {
    "python": (".py", ".pyi"),
    "typescript": (".ts", ".mts", ".cts"),
    "typescriptreact": (".tsx",),
    "javascript": (".js", ".mjs", ".cjs"),
    "javascriptreact": (".jsx",),
    "vue": (".vue",), "svelte": (".svelte",), "astro": (".astro",),
    "go": (".go",), "rust": (".rs",),
    "ruby": (".rb", ".rake", ".gemspec", ".ru"),
    "c": (".c", ".h"),
    "cpp": (".cc", ".cpp", ".cxx", ".hh", ".hpp", ".hxx"),
    "csharp": (".cs", ".csx"), "fsharp": (".fs", ".fsi", ".fsx"),
    "swift": (".swift",), "java": (".java",), "kotlin": (".kt", ".kts"),
    "yaml": (".yaml", ".yml"), "json": (".json",), "jsonc": (".jsonc",),
    "lua": (".lua",), "php": (".php",), "blade": (".blade.php",), "prisma": (".prisma",), "dart": (".dart",),
    "ocaml": (".ml", ".mli"),
    "shellscript": (".sh", ".bash", ".zsh"),
    "terraform": (".tf", ".tfvars"),
    "latex": (".tex",), "bibtex": (".bib",), "gleam": (".gleam",),
    "clojure": (".clj", ".cljc", ".edn"), "clojurescript": (".cljs",),
    "nix": (".nix",), "typst": (".typ", ".typc"), "haskell": (".hs", ".lhs"),
    "julia": (".jl",), "elixir": (".ex", ".exs"), "zig": (".zig", ".zon"),
    "dockerfile": (".dockerfile",),
    "powershell": (".ps1", ".psm1", ".psd1"),
}
LANGUAGE_BY_EXT: Dict[str, str] = {ext: lang for lang, exts in _EXTS_BY_LANGUAGE.items() for ext in exts}

_SpawnFn = Callable[[str, "ServerContext"], Optional["SpawnSpec"]]
_RootFn = Callable[[str, str], Optional[str]]


@dataclass
class SpawnSpec:
    """Result of resolving a server for a file (``None`` means skip)."""
    command: List[str]
    workspace_root: str
    cwd: str
    env: Dict[str, str] = field(default_factory=dict)
    initialization_options: Dict[str, Any] = field(default_factory=dict)
    seed_diagnostics_on_first_push: bool = False


@dataclass
class ServerDef:
    """One language server: ``resolve_root(file, ws)`` → per-server root or ``None`` to skip;
    ``build_spawn(root, ctx)`` → :class:`SpawnSpec` or ``None`` when the binary can't be found."""
    server_id: str
    extensions: Tuple[str, ...]
    resolve_root: _RootFn
    build_spawn: _SpawnFn
    seed_first_push: bool = False
    description: str = ""
    # Server handles ``workspace/didChangeWorkspaceFolders``: one process serves every project root
    # (git worktrees included) as extra workspaceFolders instead of one process per root.
    multi_root: bool = False
    # didOpen languageId; "" = derive from LANGUAGE_BY_EXT (custom servers name theirs in config).
    language_id: str = ""

    def matches(self, file_path: str) -> bool:
        return _file_ext_or_basename(file_path) in self.extensions


@dataclass
class ServerContext:
    """User policy passed into :meth:`ServerDef.build_spawn` (install strategy, overrides)."""
    workspace_root: str
    install_strategy: str = "auto"  # "auto" | "manual" | "off"
    binary_overrides: Dict[str, List[str]] = field(default_factory=dict)
    env_overrides: Dict[str, Dict[str, str]] = field(default_factory=dict)
    init_overrides: Dict[str, Dict[str, Any]] = field(default_factory=dict)
    # Whether the server may load code the project ships (see workspace.is_trusted_workspace).
    # Defaults closed: a context built without a trust decision must never run the repo's code.
    trusted: bool = False


# ---- helpers ----

# Multi-part extensions that name a different language than their last segment: ``os.path.splitext``
# would reduce ``home.blade.php`` to ``.php`` and hand Blade templates to the plain-PHP server.
_COMPOUND_EXTS = (".blade.php",)


def _file_ext_or_basename(path: str) -> str:
    """Lower-cased extension (compound ones first), or the full basename for extensionless files (``Dockerfile``)."""
    base = os.path.basename(path)
    lower = base.lower()
    return next((c for c in _COMPOUND_EXTS if lower.endswith(c)), None) or os.path.splitext(base)[1].lower() or base


def _which(*names: str) -> Optional[str]:
    """Return the full path of the first command found on PATH."""
    return next((p for n in names if (p := shutil.which(n))), None)


def _root_or_workspace(file_path: str, workspace: str, markers: Sequence[str], excludes: Sequence[str] = ()) -> Optional[str]:
    """``nearest_root`` with workspace fallback; ``None`` iff an exclude marker hit."""
    ceiling = os.path.dirname(workspace) if workspace else None
    found = nearest_root(file_path, markers, excludes=excludes, ceiling=ceiling)
    if found is None and excludes and nearest_root(file_path, markers, ceiling=ceiling) is not None:
        # None is ambiguous with excludes configured: a hit without them means
        # the exclude fired (gated off); otherwise fall back to the workspace.
        return None
    return found or workspace


def _markers_root(markers: Optional[Sequence[str]], excludes: Sequence[str] = ()) -> _RootFn:
    """Root resolver over marker files; ``None`` markers means "always the workspace root"."""
    if markers is None:
        return lambda fp, ws: ws
    return lambda fp, ws: _root_or_workspace(fp, ws, markers, excludes=excludes)


def _find_binary(ctx: ServerContext, server_id: str, which: Sequence[str], install_pkg: Optional[str]) -> Optional[str]:
    """Config override → PATH → (optional) auto-install; ``None`` when nothing resolves."""
    override = ctx.binary_overrides.get(server_id)
    bin_path = override[0] if override and override[0] and os.path.exists(override[0]) else _which(*which)
    if bin_path is None and install_pkg is not None:
        from agent.lsp.install import try_install
        bin_path = try_install(install_pkg, ctx.install_strategy)
    return bin_path


def _make_spec(root: str, ctx: ServerContext, server_id: str, command: List[str],
               base_init: Optional[Dict[str, Any]] = None, seed: bool = False) -> SpawnSpec:
    from pm import env_for

    init = ctx.init_overrides.get(server_id, {}) if base_init is None else {**base_init, **ctx.init_overrides.get(server_id, {})}
    env = env_for("node")
    env.update(ctx.env_overrides.get(server_id, {}))
    return SpawnSpec(command, root, root, env=env,
                     initialization_options=init, seed_diagnostics_on_first_push=seed)


def _simple_spawn(server_id: str, which: Sequence[str], args: Sequence[str] = (),
                  install_pkg: Optional[str] = None, base_init: Optional[Dict[str, Any]] = None,
                  seed: bool = False, untrusted_init: Optional[Dict[str, Any]] = None) -> _SpawnFn:
    """Build a spawn function for the common single-binary server shape; ``untrusted_init`` replaces
    ``base_init`` in an untrusted workspace (the server's own switch for not loading project code)."""
    def build(root: str, ctx: ServerContext) -> Optional[SpawnSpec]:
        bin_path = _find_binary(ctx, server_id, which, install_pkg)
        init = base_init if ctx.trusted or untrusted_init is None else untrusted_init
        return None if bin_path is None else _make_spec(root, ctx, server_id, [bin_path, *args], init, seed)
    return build


# ---- bespoke spawn builders ----

def _spawn_pyright(root: str, ctx: ServerContext) -> Optional[SpawnSpec]:
    bin_path = _find_binary(ctx, "pyright", ("pyright-langserver", "pyright"), "pyright")
    if bin_path is None:
        return None
    # If we got the cli ``pyright``, the langserver is its sibling — same suffix, since on Windows
    # the bare sibling is npm's unrunnable POSIX shim.
    stem, suffix = os.path.splitext(os.path.basename(bin_path))
    if stem == "pyright":
        sibling = os.path.join(os.path.dirname(bin_path), f"pyright-langserver{suffix}")
        if os.path.exists(sibling):
            bin_path = sibling
    # Point pyright at the project venv; its default "python on PATH" rarely is.  Pyright executes
    # this interpreter, so a checkout's own venv is only used when the workspace is trusted.
    py = _detect_python(root if ctx.trusted else None)
    return _make_spec(root, ctx, "pyright", [bin_path, "--stdio"], {"python": {"pythonPath": py}} if py else {})


def _detect_python(root: Optional[str]) -> Optional[str]:
    # Pyright needs the project's dependencies, not Hermes's runtime packages.  ``VIRTUAL_ENV`` is the
    # operator's own environment; ``root`` (the project's .venv/venv) is None for an untrusted workspace.
    project = (os.path.join(root, ".venv"), os.path.join(root, "venv")) if root else ()
    venvs = [v for v in (os.environ.get("VIRTUAL_ENV"), *project) if v]
    paths = (os.path.join(v, sub) for v in venvs for sub in ("bin/python", "bin/python3", "Scripts/python.exe"))
    project_python = next((p for p in paths if os.path.exists(p)), None)
    if project_python is not None:
        return project_python
    from pm import installed_package

    installed = installed_package("python")
    return str(installed.binary) if installed is not None and installed.binary is not None else None


_warned_once: set = set()


def _warn_once(key: str, message: str) -> None:
    """Log ``message`` at WARNING the first time ``key`` is seen in this process."""
    if key not in _warned_once:
        _warned_once.add(key)
        logger.warning(message)


def _spawn_bash_ls(root: str, ctx: ServerContext) -> Optional[SpawnSpec]:
    bin_path = _find_binary(ctx, "bash-language-server", ("bash-language-server",), "bash-language-server")
    if bin_path is None:
        return None
    # bash-language-server delegates diagnostics to shellcheck; without it the
    # server runs but never reports anything.  Warn once so the gap is visible.
    if _which("shellcheck") is None:
        _warn_once("shellcheck", "bash-language-server: shellcheck not found on PATH — diagnostics will be empty "
                   "until shellcheck is installed (apt: shellcheck, brew: shellcheck, scoop: shellcheck).")
    return _make_spec(root, ctx, "bash-language-server", [bin_path, "start"])


_VUE_REINSTALL = (
    "delete <HERMES_HOME>/lsp/node_modules/@vue and <HERMES_HOME>/lsp/bin/vue-language-server*, "
    "then run: hermes lsp install vue-language-server"
)
_VUE_TUNNEL_MSG = (
    "vue-language-server: the installed @vue/language-server is 3.x, which only works behind a client-hosted "
    f"tsserver tunnel Hermes does not run — no diagnostics will arrive. Reinstall the self-hosting 2.x line: {_VUE_REINSTALL}"
)
_VUE_TSDK_MSG = (
    "vue-language-server: no JavaScript TypeScript SDK (typescript/lib/typescript.js) next to the server or under "
    f"the project's node_modules — diagnostics are skipped. Reinstall (the recipe co-installs one): {_VUE_REINSTALL}"
)


def _node_modules_trees(bin_path: str, root: Optional[str]) -> List[str]:
    """``node_modules`` trees that may hold a server and its TypeScript SDK: the launcher's own tree
    (symlinks resolved), Hermes staging, then the project's (``root`` None: Hermes's trees only, for
    TypeScript's SDK pin in an untrusted workspace, whose own JavaScript must not load)."""
    from agent.lsp.install import hermes_lsp_bin_dir
    trees = [str(hermes_lsp_bin_dir().parent / "node_modules")] + ([os.path.join(root, "node_modules")] if root else [])
    real = os.path.realpath(bin_path)
    marker = f"{os.sep}node_modules{os.sep}"
    if (idx := real.rfind(marker)) >= 0:
        trees.insert(0, real[: idx + len(marker) - 1])
    return trees


def _vue_server_major(trees: Sequence[str]) -> int:
    """Major version of the first ``@vue/language-server`` found in ``trees``; 0 when unreadable."""
    import json
    for tree in trees:
        try:
            with open(os.path.join(tree, "@vue", "language-server", "package.json"), encoding="utf-8-sig") as fh:
                return int(str(json.load(fh).get("version", "")).split(".")[0])
        except (OSError, ValueError):
            continue
    return 0


def _typescript_sdk_dir(trees: Sequence[str]) -> Optional[str]:
    """First ``typescript/lib`` in ``trees`` holding a JS ``typescript.js`` (TypeScript 7+ ships none)."""
    cands = (os.path.join(tree, "typescript", "lib") for tree in trees)
    return next((c for c in cands if os.path.isfile(os.path.join(c, "typescript.js"))), None)


def _spawn_vue(root: str, ctx: ServerContext) -> Optional[SpawnSpec]:
    """Spawn @vue/language-server 2.x self-hosting TypeScript (``hybridMode`` off, explicit ``tsdk``)."""
    bin_path = _find_binary(ctx, "vue-language-server", ("vue-language-server",), "@vue/language-server")
    if bin_path is None:
        return None
    trees = _node_modules_trees(bin_path, root)
    if _vue_server_major(trees) >= 3:
        _warn_once("vue-tunnel", _VUE_TUNNEL_MSG)
        return None
    tsdk = _typescript_sdk_dir(trees)
    if tsdk is None:
        _warn_once("vue-tsdk", _VUE_TSDK_MSG)
        return None
    return _make_spec(root, ctx, "vue-language-server", [bin_path, "--stdio"],
                      {"typescript": {"tsdk": tsdk}, "vue": {"hybridMode": False}})


_TS_UNTRUSTED_MSG = (
    "typescript-language-server: no TypeScript SDK next to the server, and this workspace is untrusted so its "
    "own node_modules/typescript is not loaded — diagnostics are skipped. Reinstall: hermes lsp install "
    "typescript-language-server, or list the workspace under lsp.trusted_workspaces."
)


def _spawn_typescript(root: str, ctx: ServerContext) -> Optional[SpawnSpec]:
    """typescript-language-server loads the workspace's own ``node_modules/typescript`` unless
    ``tsserver.path`` names another, so an untrusted workspace is pinned to Hermes's copy."""
    bin_path = _find_binary(ctx, "typescript", ("typescript-language-server",), "typescript-language-server")
    if bin_path is None:
        return None
    base: Dict[str, Any] = {}
    if not ctx.trusted:
        sdk = _typescript_sdk_dir(_node_modules_trees(bin_path, None))
        if sdk is None:
            _warn_once("ts-untrusted", _TS_UNTRUSTED_MSG)
            return None
        base = {"tsserver": {"path": sdk}}
    return _make_spec(root, ctx, "typescript", [bin_path, "--stdio"], base, seed=True)


def _find_pses_bundle(ctx: ServerContext) -> Optional[str]:
    """Locate the PowerShellEditorServices bundle dir (release zip, manual install).  Resolution order:
    ``lsp.servers.powershell.command[0]`` when a directory, ``init_overrides["powershell"]["bundlePath"]``,
    ``PSES_BUNDLE_PATH`` env, then ``<HERMES_HOME>/lsp/PowerShellEditorServices``."""
    from hermes_constants import get_hermes_home
    override = ctx.binary_overrides.get("powershell")
    init = ctx.init_overrides.get("powershell", {})
    candidates = [
        override[0] if override else None,
        str(init["bundlePath"]) if isinstance(init, dict) and init.get("bundlePath") else None,
        os.environ.get("PSES_BUNDLE_PATH"),
        os.path.join(str(get_hermes_home()), "lsp", "PowerShellEditorServices"),
    ]
    for cand in filter(None, candidates):
        # Accept either the bundle root or the inner module dir.
        if os.path.isfile(os.path.join(cand, "PowerShellEditorServices", "Start-EditorServices.ps1")):
            return cand
        if os.path.isfile(os.path.join(cand, "Start-EditorServices.ps1")):
            return os.path.dirname(cand)
    return None


_PSES_MISSING_MSG = (
    "powershell: pwsh found but the PowerShellEditorServices bundle is missing. Download the release zip from "
    "https://github.com/PowerShell/PowerShellEditorServices/releases, extract it, and either set "
    "lsp.servers.powershell.command to the bundle path or unzip it to <HERMES_HOME>/lsp/PowerShellEditorServices."
)


def _spawn_powershell_es(root: str, ctx: ServerContext) -> Optional[SpawnSpec]:
    """Spawn PowerShellEditorServices: needs a ``pwsh``/``powershell`` host plus the module bundle."""
    pwsh = _which("pwsh", "powershell")
    if pwsh is None:
        return None
    bundle = _find_pses_bundle(ctx)
    if bundle is None:
        _warn_once("pses-bundle", _PSES_MISSING_MSG)
        return None
    start_script = os.path.join(bundle, "PowerShellEditorServices", "Start-EditorServices.ps1")
    # PSES writes connection info to the session details file on startup.
    session_dir = hermes_lsp_session_dir()
    inner = (
        f"& '{start_script}' -BundledModulesPath '{bundle}' "
        f"-LogPath '{os.path.join(session_dir, 'pses.log')}' "
        f"-SessionDetailsPath '{os.path.join(session_dir, f'pses-session-{os.getpid()}.json')}' "
        f"-FeatureFlags @() -AdditionalModules @() "
        f"-HostName Hermes -HostProfileId hermes -HostVersion 1.0.0 -Stdio -LogLevel Normal"
    )
    return SpawnSpec(
        [pwsh, "-NoLogo", "-NoProfile", "-NonInteractive", "-ExecutionPolicy", "Bypass", "-Command", inner],
        root, root, env=ctx.env_overrides.get("powershell", {}),
        initialization_options={k: v for k, v in ctx.init_overrides.get("powershell", {}).items() if k != "bundlePath"},
    )


def hermes_lsp_session_dir() -> str:
    """Return (and create) the dir for PSES session/log scratch files."""
    from hermes_constants import get_hermes_home
    d = os.path.join(str(get_hermes_home()), "lsp", "pses")
    os.makedirs(d, exist_ok=True)
    return d


# ---- workspace trust ----

# The only servers that start in an untrusted workspace (``workspace.is_trusted_workspace``): with the
# settings Hermes passes they run nothing the checkout ships.  Everything else waits for trust, because
# it evaluates project build files on start or on save (cargo check / build.rs / proc-macros, Gradle,
# mix.exs, build.zig, stack/cabal, Lua ``runtime.plugin``, terraform providers, prisma.config.ts, Vue's
# tsconfig ``vueCompilerOptions.plugins``, which @vue/language-core require()s from the project, ...),
# and so do user-declared ``lsp.servers`` entries, whose behaviour Hermes cannot vouch for.
UNTRUSTED_SAFE_SERVERS = frozenset({
    "pyright",                  # interpreter pinned to the operator's own (_spawn_pyright)
    "typescript",               # tsserver pinned to Hermes's SDK; plugins then resolve beside it (_spawn_typescript)
    "svelte-language-server",   # isTrusted: false — no svelte.config.js, no project svelte/prettier
    "bash-language-server",     # parses scripts; diagnostics from shellcheck on PATH
    "yaml-language-server",     # validates against JSON schemas (may fetch them); no project code
    "dockerfile-ls",            # parses the Dockerfile; never builds it
    "intelephense",             # static PHP indexer; never runs php or composer
    "clangd",                   # no --query-driver, so it never runs a project compiler
})


# ---- the registry ----

_JS_MARKERS = ["package-lock.json", "bun.lockb", "bun.lock", "pnpm-lock.yaml", "yarn.lock", "package.json", "tsconfig.json"]
_DENO_EXCLUDES = ["deno.json", "deno.jsonc"]
_root_typescript = _markers_root(_JS_MARKERS, _DENO_EXCLUDES)


def _server(server_id: str, extensions: Tuple[str, ...], description: str, *,
            markers: Optional[Sequence[str]] = None, excludes: Sequence[str] = (),
            resolve_root: Optional[_RootFn] = None, build_spawn: Optional[_SpawnFn] = None,
            which: Sequence[str] = (), args: Sequence[str] = (), install_pkg: Optional[str] = None,
            base_init: Optional[Dict[str, Any]] = None, seed: bool = False,
            untrusted_init: Optional[Dict[str, Any]] = None, multi_root: bool = False) -> ServerDef:
    """Registry entry factory: defaults to marker-based root + single-binary spawn."""
    return ServerDef(
        server_id, extensions,
        resolve_root or _markers_root(markers, excludes),
        build_spawn or _simple_spawn(server_id, which or (server_id,), args, install_pkg, base_init, seed, untrusted_init),
        seed_first_push=seed, description=description, multi_root=multi_root,
    )


SERVERS: List[ServerDef] = [
    _server("pyright", (".py", ".pyi"), "Python — Microsoft pyright",
            markers=["pyproject.toml", "setup.py", "setup.cfg", "requirements.txt", "Pipfile", "pyrightconfig.json"],
            build_spawn=_spawn_pyright, multi_root=True),
    _server("typescript", (".ts", ".tsx", ".js", ".jsx", ".mjs", ".cjs", ".mts", ".cts"),
            "JavaScript/TypeScript — typescript-language-server", resolve_root=_root_typescript,
            build_spawn=_spawn_typescript, seed=True),
    _server("vue-language-server", (".vue",), "Vue.js — @vue/language-server", resolve_root=_root_typescript,
            build_spawn=_spawn_vue),
    _server("svelte-language-server", (".svelte",), "Svelte — svelte-language-server", resolve_root=_root_typescript,
            which=("svelteserver", "svelte-language-server"), args=("--stdio",), install_pkg="svelte-language-server",
            untrusted_init={"isTrusted": False}),
    _server("astro-language-server", (".astro",), "Astro — @astrojs/language-server", resolve_root=_root_typescript,
            which=("astro-ls", "astro-language-server"), args=("--stdio",), install_pkg="@astrojs/language-server"),
    _server("gopls", (".go",), "Go — gopls", markers=["go.work", "go.mod", "go.sum"], install_pkg="gopls"),
    _server("rust-analyzer", (".rs",), "Rust — rust-analyzer", markers=["Cargo.toml", "Cargo.lock"], install_pkg="rust-analyzer"),
    _server("clangd", (".c", ".cpp", ".cc", ".cxx", ".h", ".hh", ".hpp", ".hxx"), "C/C++ — clangd",
            markers=["compile_commands.json", "compile_flags.txt", ".clangd"],
            args=("--background-index", "--clang-tidy"), install_pkg="clangd"),
    _server("bash-language-server", (".sh", ".bash", ".zsh", ".ksh"), "Bash — bash-language-server", build_spawn=_spawn_bash_ls),
    _server("yaml-language-server", (".yaml", ".yml"), "YAML — yaml-language-server",
            args=("--stdio",), install_pkg="yaml-language-server"),
    _server("lua-language-server", (".lua",), "Lua — lua-language-server",
            markers=[".luarc.json", ".luarc.jsonc", ".luacheckrc", ".stylua.toml", "stylua.toml", "selene.toml", "selene.yml"],
            install_pkg="lua-language-server"),
    # Before intelephense: Blade templates are Laravel's, plain .php stays with intelephense.
    _server("laravel-lsp", (".blade.php",), "Laravel Blade — laravel-lsp (manual: composer global require laravel/lsp)",
            markers=["artisan", "composer.json", "composer.lock"], args=("lsp",)),
    _server("intelephense", (".php",), "PHP — intelephense", markers=["composer.json", "composer.lock", ".php-version"],
            args=("--stdio",), install_pkg="intelephense", base_init={"telemetry": {"enabled": False}}),
    _server("ocaml-lsp", (".ml", ".mli"), "OCaml — ocaml-lsp", markers=["dune-project", "dune-workspace", ".merlin", "opam"],
            which=("ocamllsp",)),
    _server("dockerfile-ls", (".dockerfile", "Dockerfile"), "Dockerfile — dockerfile-language-server-nodejs",
            which=("docker-langserver",), args=("--stdio",), install_pkg="dockerfile-language-server-nodejs"),
    # terraform-ls is heavy to auto-install; require the user to provide it.
    _server("terraform-ls", (".tf", ".tfvars"), "Terraform — terraform-ls", markers=[".terraform.lock.hcl", "terraform.tfstate"],
            args=("serve",), base_init={"experimentalFeatures": {"prefillRequiredFields": True, "validateOnSave": True}}),
    _server("dart", (".dart",), "Dart — built-in language server", markers=["pubspec.yaml", "analysis_options.yaml"],
            args=("language-server", "--lsp")),
    _server("haskell-language-server", (".hs", ".lhs"), "Haskell — haskell-language-server",
            markers=["stack.yaml", "cabal.project", "hie.yaml"],
            which=("haskell-language-server-wrapper", "haskell-language-server"), args=("--lsp",)),
    _server("julia", (".jl",), "Julia — LanguageServer.jl", markers=["Project.toml", "Manifest.toml"],
            args=("--startup-file=no", "--history-file=no", "-e", "using LanguageServer; runserver()")),
    _server("clojure-lsp", (".clj", ".cljs", ".cljc", ".edn"), "Clojure — clojure-lsp",
            markers=["deps.edn", "project.clj", "shadow-cljs.edn", "bb.edn", "build.boot"], args=("listen",)),
    _server("nixd", (".nix",), "Nix — nixd", resolve_root=lambda fp, ws: nearest_root(fp, ["flake.nix"]) or ws),
    _server("zls", (".zig", ".zon"), "Zig — zls", markers=["build.zig"]),
    _server("gleam", (".gleam",), "Gleam — built-in language server", markers=["gleam.toml"], args=("lsp",)),
    _server("elixir-ls", (".ex", ".exs"), "Elixir — elixir-ls", markers=["mix.exs", "mix.lock"],
            which=("elixir-ls", "language_server.sh")),
    _server("prisma", (".prisma",), "Prisma — built-in language server", markers=["schema.prisma", "prisma/schema.prisma"],
            args=("language-server",)),
    _server("kotlin-language-server", (".kt", ".kts"), "Kotlin — kotlin-language-server",
            markers=["settings.gradle", "settings.gradle.kts", "build.gradle", "build.gradle.kts", "pom.xml"]),
    # jdtls has a complex install flow; we look for the wrapper script a manual install produces.
    _server("jdtls", (".java",), "Java — Eclipse JDT Language Server",
            markers=["pom.xml", "build.gradle", "build.gradle.kts", ".project", ".classpath", "settings.gradle"]),
    # No universal PowerShell root marker; nearest_root is exact-name only (no globs).
    _server("powershell", (".ps1", ".psm1", ".psd1"), "PowerShell — PowerShellEditorServices (manual bundle)",
            markers=["PSScriptAnalyzerSettings.psd1"], build_spawn=_spawn_powershell_es),
]


def find_server_for_file(file_path: str, servers: Optional[Sequence[ServerDef]] = None) -> Optional[ServerDef]:
    """Return the first entry of ``servers`` (default: the built-in registry) that handles ``file_path``."""
    return next((srv for srv in (SERVERS if servers is None else servers) if srv.matches(file_path)), None)


def language_id_for(path: str, srv: Optional[ServerDef] = None) -> str:
    """Return the LSP languageId to send in didOpen for ``path`` (a custom server's own id wins)."""
    if srv is not None and srv.language_id:
        return srv.language_id
    return LANGUAGE_BY_EXT.get(_file_ext_or_basename(path), "plaintext")


def _custom_spawn(server_id: str, command: Sequence[str]) -> _SpawnFn:
    """Spawn builder for a config-declared server: ``command[0]`` is a path or a PATH lookup, no auto-install."""
    def build(root: str, ctx: ServerContext) -> Optional[SpawnSpec]:
        bin_path = _which(os.path.expanduser(command[0]))
        if bin_path is None:
            _warn_once(f"custom:{server_id}", f"lsp.servers.{server_id}: command {command[0]!r} not found on PATH — server skipped")
            return None
        return _make_spec(root, ctx, server_id, [bin_path, *command[1:]])
    return build


def custom_servers(servers_cfg: Any) -> List[ServerDef]:
    """``lsp.servers`` entries that declare ``extensions`` and name no built-in server are user-declared
    servers (issue #100257).  They go AHEAD of the built-ins so a custom entry can claim an extension;
    malformed entries are logged and skipped so one typo never disables the rest of the subsystem."""
    if not isinstance(servers_cfg, dict):
        return []
    builtin = {s.server_id for s in SERVERS}
    out: List[ServerDef] = []
    for server_id, cfg in servers_cfg.items():
        if server_id in builtin or not isinstance(cfg, dict) or "extensions" not in cfg:
            continue
        command, exts, markers = cfg.get("command"), cfg.get("extensions"), cfg.get("root_markers")
        if not (isinstance(command, list) and command and all(isinstance(c, str) and c for c in command)
                and isinstance(exts, list) and exts and all(isinstance(e, str) and e for e in exts)):
            logger.warning("lsp.servers.%s: custom server needs command: [bin, ...args] and extensions: [.ext, ...] — ignored", server_id)
            continue
        out.append(ServerDef(
            str(server_id), tuple(e.lower() if e.startswith(".") else e for e in exts),
            _markers_root([str(m) for m in markers] if isinstance(markers, list) and markers else None),
            _custom_spawn(str(server_id), command),
            description=str(cfg.get("description") or f"{server_id} — custom (lsp.servers)"),
            language_id=str(cfg.get("language_id") or ""),
        ))
    return out


__all__ = ["ServerDef", "ServerContext", "SpawnSpec", "SERVERS", "UNTRUSTED_SAFE_SERVERS", "custom_servers",
           "find_server_for_file", "language_id_for", "LANGUAGE_BY_EXT"]