/** Session-scoped embedded LSP runtime and tool materialization for agent bundles. */
import { normalizeOptionalLowercaseString } from "@openclaw/normalization-core/string-coerce";
import type { OpenClawConfig } from "../config/types.openclaw.js";
import { createAbortError } from "../infra/abort-signal.js";
import { toErrorObject } from "../infra/errors.js";
import { logDebug, logWarn } from "../logger.js";
import type { PluginManifestRegistry } from "../plugins/manifest-registry.js";
import { setPluginToolMeta } from "../plugins/tool-metadata.js";
import {
  closeOwnedStdioProcess,
  OwnedStdioCleanupError,
  type OwnedStdioProcess,
} from "../process/owned-stdio.js";
import { createPendingRequestRegistry } from "../shared/pending-request-registry.js";
import { settlesWithin } from "../shared/settle-within.js";
import {
  defaultBundleLspRuntimeDependencies,
  type BundleLspRuntimeDependencies,
} from "./agent-bundle-lsp-dependencies.js";
import {
  resolveStdioMcpServerLaunchConfig,
  describeStdioMcpServerLaunchConfig,
} from "./mcp-stdio.js";
import { recordAgentCleanupFailure } from "./run-cleanup-timeout.js";
import type { AgentToolResult } from "./runtime/index.js";
import type { AnyAgentTool } from "./tools/common.js";

// Minimal LSP JSON-RPC framing over stdio (Content-Length header + JSON body).

type LspSession = {
  serverName: string;
  process: OwnedStdioProcess;
  requestId: number;
  pendingRequests: ReturnType<typeof createPendingRequestRegistry<number, unknown, undefined>>;
  input: LspInputBuffer;
  initialized: boolean;
  capabilities: LspServerCapabilities;
  disposed: boolean;
  forceClose: boolean;
  disposal?: Promise<void>;
  // Preserve a terminal process/transport failure so later requests reject immediately
  // instead of waiting for the per-request timeout.
  failure?: Error;
};

type LspServerCapabilities = {
  hoverProvider?: boolean;
  completionProvider?: boolean;
  definitionProvider?: boolean;
  referencesProvider?: boolean;
  diagnosticProvider?: boolean;
  [key: string]: unknown;
};

/** Materialized LSP tools plus session capabilities and cleanup handle. */
type BundleLspToolRuntime = {
  tools: AnyAgentTool[];
  sessions: Array<{ serverName: string; capabilities: LspServerCapabilities }>;
  dispose: () => Promise<void>;
};

type LspPositionParams = {
  uri: string;
  line: number;
  character: number;
};

const LSP_SHUTDOWN_GRACE_MS = 500;
const LSP_PROCESS_TREE_KILL_GRACE_MS = 1_000;
const activeBundleLspSessions = new Set<LspSession>();

function createLspSession(serverName: string, child: OwnedStdioProcess): LspSession {
  return {
    serverName,
    process: child,
    requestId: 0,
    pendingRequests: createPendingRequestRegistry<number, unknown, undefined>(),
    input: { buffer: Buffer.alloc(0), length: 0 },
    initialized: false,
    capabilities: {},
    disposed: false,
    forceClose: false,
  };
}

function registerActiveLspSession(session: LspSession): void {
  activeBundleLspSessions.add(session);
}

function rememberLspFailure(session: LspSession, error: Error): void {
  session.failure ??= error;
}

function failLspSession(session: LspSession, error: Error): void {
  rememberLspFailure(session, error);
  session.pendingRequests.rejectAll(session.failure ?? error);
}

function lspProcessExitError(
  session: LspSession,
  code: number | null,
  signal: NodeJS.Signals | null,
) {
  return new Error(`LSP server "${session.serverName}" exited (${signal ?? code ?? "unknown"})`);
}

function attachLspProcessHandlers(session: LspSession): void {
  session.process.onError((error, source) => {
    if (source === "stderr") {
      logWarn(`bundle-lsp:${session.serverName}: stderr failed: ${String(error)}`);
    } else {
      session.forceClose = true;
      failLspSession(session, error);
    }
  });
  session.process.onExit((code, signal) => {
    // Block new requests immediately, but let stdout drain any final response before close.
    rememberLspFailure(session, lspProcessExitError(session, code, signal));
  });
  void session.process.wait().then(
    ({ code, signal }) => failLspSession(session, lspProcessExitError(session, code, signal)),
    (error: unknown) => failLspSession(session, toErrorObject(error, "LSP process failed")),
  );
  session.process.onStdout(
    () => {},
    (chunk) => handleIncomingData(session, chunk),
  );
  session.process.onStderr((chunk) => {
    for (const line of chunk.split(/\r?\n/).filter(Boolean)) {
      logDebug(`bundle-lsp:${session.serverName}: ${line.trim()}`);
    }
  });
}

function encodeLspMessage(body: unknown): string {
  const json = JSON.stringify(body);
  return `Content-Length: ${Buffer.byteLength(json, "utf-8")}\r\n\r\n${json}`;
}

const LSP_HEADER_SEPARATOR = Buffer.from("\r\n\r\n", "ascii");
const MAX_LSP_HEADER_BYTES = 8 * 1024;
const MAX_LSP_BODY_BYTES = 64 * 1024 * 1024;
const LSP_BODY_DECODER = new TextDecoder("utf-8", { fatal: true, ignoreBOM: true });

class LspFramingError extends Error {
  override readonly name = "LspFramingError";
}

type LspParseResult =
  | { readonly ok: true; readonly messages: unknown[]; readonly consumed: number }
  | { readonly ok: false; readonly messages: unknown[]; readonly error: LspFramingError };

type LspInputBuffer = {
  buffer: Buffer;
  length: number;
  body?: { start: number; end: number };
};

function framingError(messages: unknown[], detail: string): LspParseResult {
  return {
    ok: false,
    messages,
    error: new LspFramingError(`LSP framing error: ${detail}`),
  };
}

function parseContentLength(header: string): number | LspFramingError {
  const values: string[] = [];
  for (const line of header.split("\r\n")) {
    const separator = line.indexOf(":");
    if (separator === -1) {
      return new LspFramingError("LSP framing error: header line must contain a colon");
    }
    if (line.slice(0, separator).trim().toLowerCase() === "content-length") {
      values.push(line.slice(separator + 1).trim());
    }
  }
  if (values.length !== 1) {
    return new LspFramingError(
      `LSP framing error: expected exactly one Content-Length header, received ${values.length}`,
    );
  }
  const value = values[0];
  if (value === undefined || !/^[0-9]+$/.test(value)) {
    return new LspFramingError("LSP framing error: Content-Length must be decimal digits");
  }
  const length = Number(value);
  if (!Number.isSafeInteger(length) || length <= 0) {
    return new LspFramingError("LSP framing error: Content-Length must be a positive safe integer");
  }
  if (length > MAX_LSP_BODY_BYTES) {
    return new LspFramingError(
      `LSP framing error: Content-Length exceeds ${MAX_LSP_BODY_BYTES} bytes`,
    );
  }
  return length;
}

function parseLspMessages(input: LspInputBuffer): LspParseResult {
  const messages: unknown[] = [];
  let consumed = 0;

  while (true) {
    if (!input.body) {
      const remaining = input.buffer.subarray(consumed, input.length);
      const headerEnd = remaining.indexOf(LSP_HEADER_SEPARATOR);
      if (headerEnd === -1) {
        const maxIncompleteHeaderBytes = MAX_LSP_HEADER_BYTES + LSP_HEADER_SEPARATOR.length - 1;
        return remaining.length > maxIncompleteHeaderBytes
          ? framingError(messages, `header exceeds ${MAX_LSP_HEADER_BYTES} bytes`)
          : { ok: true, messages, consumed };
      }
      if (headerEnd > MAX_LSP_HEADER_BYTES) {
        return framingError(messages, `header exceeds ${MAX_LSP_HEADER_BYTES} bytes`);
      }

      const contentLength = parseContentLength(remaining.subarray(0, headerEnd).toString("ascii"));
      if (contentLength instanceof LspFramingError) {
        return { ok: false, messages, error: contentLength };
      }
      const start = consumed + headerEnd + LSP_HEADER_SEPARATOR.length;
      input.body = { start, end: start + contentLength };
    }
    if (input.length < input.body.end) {
      return { ok: true, messages, consumed };
    }

    let body: string;
    try {
      body = LSP_BODY_DECODER.decode(input.buffer.subarray(input.body.start, input.body.end));
    } catch {
      return framingError(messages, "body is not valid UTF-8");
    }
    try {
      messages.push(JSON.parse(body));
    } catch (error) {
      return framingError(
        messages,
        `body is not valid JSON: ${error instanceof Error ? error.message : String(error)}`,
      );
    }
    consumed = input.body.end;
    input.body = undefined;
  }
}

function lspAbortError(signal?: AbortSignal): Error {
  return signal?.reason instanceof Error
    ? signal.reason
    : createAbortError("LSP request aborted", { cause: signal?.reason });
}

function throwIfLspAborted(signal?: AbortSignal): void {
  if (signal?.aborted) {
    throw lspAbortError(signal);
  }
}

function lspSessionDisposedError(): Error {
  return new Error("LSP session disposed");
}

function sendRequest(
  session: LspSession,
  method: string,
  params?: unknown,
  signal?: AbortSignal,
): Promise<unknown> {
  // Disposal closes tool requests before the child finishes its shutdown handshake.
  if (session.disposed && method !== "shutdown") {
    return Promise.reject(lspSessionDisposedError());
  }
  if (session.failure) {
    return Promise.reject(session.failure);
  }
  if (signal?.aborted) {
    return Promise.reject(lspAbortError(signal));
  }
  const id = ++session.requestId;
  const onAbort = () => {
    const aborted = session.pendingRequests.take(id);
    if (!aborted) {
      return;
    }
    // Bundle tools share the server process, so cancel only this request.
    try {
      session.process.stdin?.write(
        encodeLspMessage({ jsonrpc: "2.0", method: "$/cancelRequest", params: { id } }),
      );
    } catch {
      // Best-effort notification; the local tool promise must still settle.
    }
    aborted.reject(lspAbortError(signal));
  };
  const pending = session.pendingRequests.add(id, {
    value: undefined,
    timeoutMs: 10_000,
    timeoutError: () => new Error(`LSP request ${method} timed out`),
    dispose: () => signal?.removeEventListener("abort", onAbort),
  });
  if (!pending) {
    return Promise.reject(new Error(`LSP request id collision: ${id}`));
  }
  signal?.addEventListener("abort", onAbort, { once: true });
  const message = { jsonrpc: "2.0", id, method, params };
  try {
    const encoded = encodeLspMessage(message);
    session.process.stdin?.write(encoded);
  } catch (error) {
    // Preserve Promise-executor behavior for synchronous stream failures; timeout owns cleanup.
    pending.reject(error);
  }
  return pending.promise;
}

function handleIncomingData(session: LspSession, chunk: Buffer | string) {
  const bytes = typeof chunk === "string" ? Buffer.from(chunk, "utf8") : chunk;
  const input = session.input;
  const length = input.length + bytes.length;
  if (length > input.buffer.length) {
    // Grow geometrically while a frame arrives, instead of copying its full
    // prefix on every stdout chunk. Only input.length bytes are initialized.
    const capacity = Math.max(
      length,
      Math.min(
        Math.max(4096, input.buffer.length * 2),
        MAX_LSP_HEADER_BYTES + LSP_HEADER_SEPARATOR.length + MAX_LSP_BODY_BYTES,
      ),
    );
    const buffer = Buffer.allocUnsafe(capacity);
    input.buffer.copy(buffer, 0, 0, input.length);
    input.buffer = buffer;
  }
  bytes.copy(input.buffer, input.length);
  input.length = length;
  const parsed = parseLspMessages(input);
  if (!parsed.ok || parsed.consumed === input.length) {
    session.input = { buffer: Buffer.alloc(0), length: 0 };
  } else if (parsed.consumed > 0) {
    // Detach the incomplete tail from completed frames and release spare capacity.
    input.buffer = Buffer.from(input.buffer.subarray(parsed.consumed, input.length));
    input.length -= parsed.consumed;
    if (input.body) {
      input.body.start -= parsed.consumed;
      input.body.end -= parsed.consumed;
    }
  }

  for (const msg of parsed.messages) {
    if (typeof msg !== "object" || msg === null) {
      continue;
    }
    const record = msg as Record<string, unknown>;

    if ("id" in record && typeof record.id === "number") {
      const pending = session.pendingRequests.take(record.id);
      if (pending) {
        if ("error" in record) {
          pending.reject(new Error(JSON.stringify(record.error)));
        } else {
          pending.resolve(record.result);
        }
      }
    }
    // Notifications (no id) are logged but not acted on
    if ("method" in record && !("id" in record)) {
      logDebug(`bundle-lsp:${session.serverName}: notification ${String(record.method)}`);
    }
  }
  if (!parsed.ok) {
    session.forceClose = true;
    failLspSession(session, parsed.error);
    void disposeSession(session).catch(() => {});
  }
}

async function initializeSession(
  session: LspSession,
  signal?: AbortSignal,
): Promise<LspServerCapabilities> {
  const result = (await sendRequest(
    session,
    "initialize",
    {
      processId: process.pid,
      rootUri: null,
      capabilities: {
        textDocument: {
          hover: { contentFormat: ["plaintext", "markdown"] },
          completion: { completionItem: { snippetSupport: false } },
          definition: {},
          references: {},
        },
      },
    },
    signal,
  )) as { capabilities?: LspServerCapabilities } | undefined;
  throwIfLspAborted(signal);

  // Send initialized notification
  session.process.stdin?.write(
    encodeLspMessage({ jsonrpc: "2.0", method: "initialized", params: {} }),
  );

  session.initialized = true;
  return result?.capabilities ?? {};
}

function disposeSession(session: LspSession): Promise<void> {
  if (session.disposal) {
    return session.disposal;
  }
  session.disposed = true;
  // Release abort listeners before shutdown forbids cancellation notifications.
  session.pendingRequests.rejectAll(lspSessionDisposedError());
  session.disposal = (async () => {
    if (session.initialized && !session.failure) {
      try {
        const shutdown = sendRequest(session, "shutdown").catch(() => undefined);
        await settlesWithin(shutdown, LSP_SHUTDOWN_GRACE_MS);
        session.process.stdin?.write(
          encodeLspMessage({ jsonrpc: "2.0", method: "exit", params: null }),
        );
      } catch {
        // Protocol shutdown is advisory; the process owner still joins physical cleanup.
      }
    }
    session.pendingRequests.rejectAll(lspSessionDisposedError());
    try {
      await closeOwnedStdioProcess(session.process, {
        graceMs: LSP_PROCESS_TREE_KILL_GRACE_MS,
        force: session.forceClose,
      });
    } catch (error) {
      recordAgentCleanupFailure();
      logWarn(
        `bundle-lsp:${session.serverName}: process cleanup could not confirm descendant shutdown; inspect this server before retrying automatic recovery.`,
      );
      throw error;
    } finally {
      activeBundleLspSessions.delete(session);
    }
  })();
  return session.disposal;
}

async function disposeSessions(sessions: Iterable<LspSession>): Promise<void> {
  const results = await Promise.allSettled(
    Array.from(sessions, (session) => disposeSession(session)),
  );
  if (results.some((result) => result.status === "rejected")) {
    recordAgentCleanupFailure();
  }
}

function createLspPositionTool(params: {
  session: LspSession;
  toolName: string;
  label: string;
  description: string;
  method: string;
  resultLabel: string;
}): AnyAgentTool {
  return {
    name: params.toolName,
    label: params.label,
    description: params.description,
    parameters: {
      type: "object",
      properties: {
        uri: { type: "string", description: "File URI (file:///path/to/file)" },
        line: { type: "number", description: "Zero-based line number" },
        character: { type: "number", description: "Zero-based character offset" },
      },
      required: ["uri", "line", "character"],
    },
    execute: async (_toolCallId, input, signal) => {
      const position = input as LspPositionParams;
      const result = await sendRequest(
        params.session,
        params.method,
        {
          textDocument: { uri: position.uri },
          position: { line: position.line, character: position.character },
        },
        signal,
      );
      return formatLspResult(params.session.serverName, params.resultLabel, result);
    },
  };
}

function buildLspTools(session: LspSession): AnyAgentTool[] {
  const tools: AnyAgentTool[] = [];
  const caps = session.capabilities;
  const serverLabel = session.serverName;

  if (caps.hoverProvider) {
    tools.push(
      createLspPositionTool({
        session,
        toolName: `lsp_hover_${serverLabel}`,
        label: `LSP Hover (${serverLabel})`,
        description: `Get hover information for a symbol at a position in a file via the ${serverLabel} language server.`,
        method: "textDocument/hover",
        resultLabel: "hover",
      }),
    );
  }

  if (caps.definitionProvider) {
    tools.push(
      createLspPositionTool({
        session,
        toolName: `lsp_definition_${serverLabel}`,
        label: `LSP Go to Definition (${serverLabel})`,
        description: `Find the definition of a symbol at a position in a file via the ${serverLabel} language server.`,
        method: "textDocument/definition",
        resultLabel: "definition",
      }),
    );
  }

  if (caps.referencesProvider) {
    tools.push({
      name: `lsp_references_${serverLabel}`,
      label: `LSP Find References (${serverLabel})`,
      description: `Find all references to a symbol at a position in a file via the ${serverLabel} language server.`,
      parameters: {
        type: "object",
        properties: {
          uri: { type: "string", description: "File URI (file:///path/to/file)" },
          line: { type: "number", description: "Zero-based line number" },
          character: { type: "number", description: "Zero-based character offset" },
          includeDeclaration: {
            type: "boolean",
            description: "Include the declaration in results",
          },
        },
        required: ["uri", "line", "character"],
      },
      execute: async (_toolCallId, input, signal) => {
        const params = input as {
          uri: string;
          line: number;
          character: number;
          includeDeclaration?: boolean;
        };
        const result = await sendRequest(
          session,
          "textDocument/references",
          {
            textDocument: { uri: params.uri },
            position: { line: params.line, character: params.character },
            context: { includeDeclaration: params.includeDeclaration ?? true },
          },
          signal,
        );
        return formatLspResult(serverLabel, "references", result);
      },
    });
  }

  return tools;
}

function formatLspResult(
  serverName: string,
  method: string,
  result: unknown,
): AgentToolResult<unknown> {
  const text =
    result !== null && result !== undefined
      ? JSON.stringify(result, null, 2)
      : `No ${method} result from ${serverName}`;
  return {
    content: [{ type: "text", text }],
    details: { lspServer: serverName, lspMethod: method },
  };
}

export async function createBundleLspToolRuntime(params: {
  workspaceDir: string;
  cfg?: OpenClawConfig;
  abortSignal?: AbortSignal;
  reservedToolNames?: Iterable<string>;
  manifestRegistry?: Pick<PluginManifestRegistry, "plugins">;
  dependencies?: BundleLspRuntimeDependencies;
}): Promise<BundleLspToolRuntime> {
  throwIfLspAborted(params.abortSignal);
  const dependencies = params.dependencies ?? defaultBundleLspRuntimeDependencies;
  const loaded = dependencies.loadLspConfig({
    workspaceDir: params.workspaceDir,
    cfg: params.cfg,
    manifestRegistry: params.manifestRegistry,
  });
  for (const diagnostic of loaded.diagnostics) {
    logWarn(`bundle-lsp: ${diagnostic.pluginId}: ${diagnostic.message}`);
  }
  // Skip spawning when no LSP servers are configured.
  if (Object.keys(loaded.lspServers).length === 0) {
    return { tools: [], sessions: [], dispose: async () => {} };
  }

  const reservedNames = new Set(
    Array.from(params.reservedToolNames ?? [], (name) =>
      normalizeOptionalLowercaseString(name),
    ).filter(Boolean),
  );
  const sessions: LspSession[] = [];
  const tools: AnyAgentTool[] = [];

  try {
    for (const [serverName, rawServer] of Object.entries(loaded.lspServers)) {
      throwIfLspAborted(params.abortSignal);
      const launch = resolveStdioMcpServerLaunchConfig(rawServer);
      if (!launch.ok) {
        logWarn(`bundle-lsp: skipped server "${serverName}" because ${launch.reason}.`);
        continue;
      }
      const launchConfig = launch.config;
      let session: LspSession | undefined;

      try {
        session = createLspSession(
          serverName,
          await dependencies.spawnServerProcess(launchConfig, { abortSignal: params.abortSignal }),
        );
        registerActiveLspSession(session);
        attachLspProcessHandlers(session);
        throwIfLspAborted(params.abortSignal);

        const capabilities = await initializeSession(session, params.abortSignal);
        throwIfLspAborted(params.abortSignal);
        session.capabilities = capabilities;
        sessions.push(session);

        const serverTools = buildLspTools(session);
        for (const tool of serverTools) {
          const normalizedName = normalizeOptionalLowercaseString(tool.name);
          if (!normalizedName) {
            continue;
          }
          if (reservedNames.has(normalizedName)) {
            logWarn(
              `bundle-lsp: skipped tool "${tool.name}" from server "${serverName}" because the name already exists.`,
            );
            continue;
          }
          reservedNames.add(normalizedName);
          setPluginToolMeta(tool, {
            pluginId: "bundle-lsp",
            optional: false,
          });
          tools.push(tool);
        }

        logDebug(
          `bundle-lsp: started "${serverName}" (${describeStdioMcpServerLaunchConfig(launchConfig)}) with ${serverTools.length} tools`,
        );
      } catch (error) {
        if (session) {
          await disposeSessions([session]);
        } else if (error instanceof OwnedStdioCleanupError) {
          recordAgentCleanupFailure();
        }
        if (!params.abortSignal?.aborted || error instanceof OwnedStdioCleanupError) {
          logWarn(
            `bundle-lsp: failed to start server "${serverName}" (${describeStdioMcpServerLaunchConfig(launchConfig)}): ${String(error)}`,
          );
        }
        throwIfLspAborted(params.abortSignal);
      }
    }

    return {
      tools,
      sessions: sessions.map((s) => ({
        serverName: s.serverName,
        capabilities: s.capabilities,
      })),
      dispose: () => disposeSessions(sessions),
    };
  } catch (error) {
    await disposeSessions(sessions);
    throw error;
  }
}

export async function disposeAllBundleLspRuntimes(): Promise<void> {
  await disposeSessions(activeBundleLspSessions);
}