Refactored CLI to support multiple commands as sk-az-tools do. Added table-info command.

src/cli/commands/table-info.ts

@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: MIT
+
+import {
+  readCsvFromStdin,
+  readJsonFromStdin,
+} from "../utils.ts";
+
+type TableInfoCommandValues = {
+  from?: string;
+  [key: string]: string | boolean | undefined;
+};
+
+type RowObject = Record<string, unknown>;
+
+type ValueType = "string" | "number" | "boolean" | "object" | "array" | "null" | "unknown";
+
+function getType(value: unknown): ValueType {
+  if (value === null) return "null";
+  if (Array.isArray(value)) return "array";
+  if (value === undefined) return "unknown";
+  if (typeof value === "string") return "string";
+  if (typeof value === "number") return "number";
+  if (typeof value === "boolean") return "boolean";
+  if (typeof value === "object") return "object";
+  return "unknown";
+}
+
+function normalizeRows(input: unknown): { rowCount: number; rows: RowObject[] } {
+  if (Array.isArray(input)) {
+    return {
+      rowCount: input.length,
+      rows: input.map((item) =>
+        item && typeof item === "object" && !Array.isArray(item)
+          ? item as RowObject
+          : { value: item }
+      ),
+    };
+  }
+
+  if (input && typeof input === "object") {
+    return {
+      rowCount: 1,
+      rows: [input as RowObject],
+    };
+  }
+
+  return {
+    rowCount: 1,
+    rows: [{ value: input }],
+  };
+}
+
+function inferColumnType(rows: RowObject[], column: string): string {
+  const kinds = new Set<ValueType>();
+
+  for (const row of rows) {
+    if (!(column in row)) {
+      continue;
+    }
+
+    const kind = getType(row[column]);
+    if (kind !== "unknown") {
+      kinds.add(kind);
+    }
+  }
+
+  if (kinds.size === 0) {
+    return "unknown";
+  }
+
+  if (kinds.size === 1) {
+    return [...kinds][0];
+  }
+
+  if (kinds.size === 2 && kinds.has("null")) {
+    return [...kinds].find((kind) => kind !== "null") ?? "unknown";
+  }
+
+  return `mixed(${[...kinds].join("|")})`;
+}
+
+function buildInfo(input: unknown): string {
+  const { rowCount, rows } = normalizeRows(input);
+  const columns = [...new Set(rows.flatMap((row) => Object.keys(row)))];
+
+  const lines = [
+    `Number of columns: ${columns.length}`,
+    `Number of rows: ${rowCount}`,
+    "",
+    "Columns:",
+  ];
+
+  if (columns.length === 0) {
+    lines.push("- (none)");
+    return lines.join("\n");
+  }
+
+  for (const column of columns) {
+    lines.push(`- ${column}: ${inferColumnType(rows, column)}`);
+  }
+
+  return lines.join("\n");
+}
+
+export function usageTableInfo(): string {
+  return `Usage: sk-tools table-info [--from|-F <json|csv|tsv>]
+
+Options:
+  --from, -F <json|csv|tsv>  Input format on stdin (default: json)`;
+}
+
+export async function runTableInfoCommand(values: TableInfoCommandValues): Promise<string> {
+  const from = (values.from ?? "json").toString().trim().toLowerCase();
+
+  if (from === "json") {
+    return buildInfo(await readJsonFromStdin());
+  }
+  if (from === "csv") {
+    return buildInfo(await readCsvFromStdin(","));
+  }
+  if (from === "tsv") {
+    return buildInfo(await readCsvFromStdin("\t"));
+  }
+
+  throw new Error(`Invalid --from '${values.from}'. Allowed: json, csv, tsv`);
+}