import { randomUUID } from "node:crypto";
import { appendFileSync, statSync } from "node:fs";

export type CliInvocationObservation = {
  version: 1;
  id: string;
  tool: string;
  startedAt: number;
  endedAt: number;
  durationMs: number;
  exitCode: number;
  errorType?: string;
  retryable?: boolean;
};

const SAFE_FILE =
  /^\/tmp\/dench-harness-a\/[a-f0-9-]{36}\/workspace\/\.dench\/observations\/[a-zA-Z0-9._-]+\.jsonl$/;
const SAFE_NAME = /^[a-z][a-z0-9_.-]{0,119}$/;
const SIDECAR_LIMIT = 65_536;
const KNOWN_ROOTS = new Set([
  "ads",
  "agent",
  "agents",
  "approval",
  "approvals",
  "artifacts",
  "backend",
  "billing",
  "browser",
  "campaign",
  "chat",
  "companies",
  "context",
  "create",
  "crm",
  "cron",
  "email",
  "env",
  "files",
  "fs",
  "help",
  "identity",
  "image",
  "instructions",
  "integrations",
  "jobs",
  "leads",
  "lists",
  "logout",
  "meetings",
  "members",
  "mem",
  "memory",
  "model",
  "notifications",
  "onboard",
  "organisation",
  "project",
  "reference",
  "register",
  "request",
  "secrets",
  "sessions",
  "signin",
  "status",
  "settings",
  "setup",
  "suggested-work",
  "tool",
  "tools",
  "upgrade",
  "use",
  "user",
  "version",
  "web",
  "what-can-i-do",
]);
const KNOWN_SUBCOMMANDS = new Set([
  "add",
  "approve",
  "archive",
  "cancel",
  "clear",
  "clone",
  "collapse",
  "complete",
  "compute",
  "configure",
  "create",
  "create-many",
  "create-subtask",
  "delete",
  "disable",
  "draft",
  "edit",
  "enable",
  "expand",
  "export",
  "follow",
  "get",
  "help",
  "hide",
  "history",
  "import",
  "info",
  "install",
  "list",
  "me",
  "mine",
  "move",
  "new",
  "parent",
  "pause",
  "poll",
  "presence",
  "preview",
  "priority",
  "query",
  "read",
  "register",
  "reject",
  "remove",
  "rename",
  "reopen",
  "reorder",
  "repeat",
  "resize",
  "resume",
  "roles",
  "run",
  "save",
  "scope",
  "search",
  "send",
  "series",
  "set",
  "show",
  "status",
  "stop",
  "subtasks",
  "sync",
  "tree",
  "unarchive",
  "uninstall",
  "update",
  "validate",
  "watch",
]);
const NESTED_NAMESPACES = new Set([
  "actions",
  "analytics",
  "builder",
  "cells",
  "docs",
  "drafts",
  "entries",
  "fields",
  "inbox",
  "objects",
  "reports",
  "sidebar",
  "sources",
  "statuses",
  "tasks",
  "transactions",
  "views",
]);

function words(argv: readonly string[]) {
  const result: string[] = [];
  for (let index = 0; index < argv.length; index++) {
    const value = argv[index];
    if (!value || value === "--") break;
    if (value.startsWith("-")) {
      if (!["--json", "--help", "-h", "--staging", "--prod"].includes(value))
        index++;
      continue;
    }
    result.push(value.toLowerCase().replace(/[^a-z0-9_-]/g, "-"));
  }
  return result;
}

export function normalizedCliTool(argv: readonly string[]) {
  const [root = "unknown", ...rest] = words(argv);
  const canonicalRoot =
    root === "campaigns"
      ? "campaign"
      : root === "routine" || root === "routines"
        ? "cron"
        : root === "ad" || root === "adline"
          ? "ads"
          : root;
  const parts = [
    "dench",
    KNOWN_ROOTS.has(canonicalRoot) ? canonicalRoot : "unknown",
  ];
  if (KNOWN_SUBCOMMANDS.has(rest[0]) || NESTED_NAMESPACES.has(rest[0]))
    parts.push(rest[0]);
  if (NESTED_NAMESPACES.has(rest[0]) && KNOWN_SUBCOMMANDS.has(rest[1]))
    parts.push(rest[1]);
  const name = parts.join(".");
  return SAFE_NAME.test(name) ? name : "dench.unknown";
}

function safeErrorType(value: unknown) {
  const raw = typeof value === "string" ? value.toLowerCase() : "cli_error";
  return SAFE_NAME.test(raw) ? raw : "cli_error";
}

export function beginCliInvocation(
  argv: readonly string[],
  env: NodeJS.ProcessEnv = process.env,
) {
  const file = env.DENCH_HARNESS_OBSERVATION_FILE?.trim();
  if (!file || !SAFE_FILE.test(file)) return null;
  return {
    file,
    id: randomUUID(),
    tool: normalizedCliTool(argv),
    startedAt: Date.now(),
  };
}

export function finishCliInvocation(
  started: ReturnType<typeof beginCliInvocation>,
  result: { exitCode: number; errorType?: unknown; retryable?: unknown },
) {
  if (!started) return;
  const endedAt = Date.now();
  const observation: CliInvocationObservation = {
    version: 1,
    id: started.id,
    tool: started.tool,
    startedAt: started.startedAt,
    endedAt,
    durationMs: Math.max(0, endedAt - started.startedAt),
    exitCode: Number.isSafeInteger(result.exitCode) ? result.exitCode : 1,
    ...(result.exitCode === 0
      ? {}
      : { errorType: safeErrorType(result.errorType) }),
    ...(typeof result.retryable === "boolean"
      ? { retryable: result.retryable }
      : {}),
  };
  try {
    const line = `${JSON.stringify(observation)}\n`;
    let size = 0;
    try {
      size = statSync(started.file).size;
    } catch {}
    if (size + Buffer.byteLength(line) > SIDECAR_LIMIT) return;
    appendFileSync(started.file, line, {
      encoding: "utf8",
      mode: 0o600,
    });
  } catch {
    // Harness telemetry must never change CLI behavior.
  }
}