Migrated to TypeScript.

src/markdown.ts

@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: MIT
+
+type Scalar = string | number | boolean | null | undefined;
+type ScalarRow = Record<string, Scalar>;
+
+type HeaderSpec =
+  | { mode: "default" }
+  | { mode: "auto" }
+  | { mode: "original" }
+  | { mode: "list"; labels: string[] }
+  | { mode: "map"; map: Record<string, string> };
+
+function formatCell(value: unknown): string {
+  const text = value == null
+    ? ""
+    : String(value);
+  return text.replaceAll("|", "\\|").replaceAll("\n", "<br>");
+}
+
+function isGuid(value: unknown): value is string {
+  return typeof value === "string"
+    && /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i.test(value);
+}
+
+function toAutoHeaderLabel(key: string): string {
+  const withSpaces = String(key)
+    .replace(/[_-]+/g, " ")
+    .replace(/([a-z0-9])([A-Z])/g, "$1 $2")
+    .replace(/\s+/g, " ")
+    .trim();
+  return withSpaces
+    .split(" ")
+    .filter(Boolean)
+    .map((part) => part[0].toUpperCase() + part.slice(1))
+    .join(" ");
+}
+
+function isScalar(value: unknown): value is Scalar {
+  return value == null || typeof value !== "object";
+}
+
+function getScalarRowsAndHeaders(value: unknown): { headers: string[]; rows: ScalarRow[] } {
+  let rows: Array<Record<string, unknown>>;
+  if (Array.isArray(value)) {
+    rows = value.map((item) =>
+      item && typeof item === "object" && !Array.isArray(item)
+        ? item as Record<string, unknown>
+        : { value: item },
+    );
+  } else if (value && typeof value === "object") {
+    rows = [value as Record<string, unknown>];
+  } else {
+    rows = [{ value }];
+  }
+
+  if (rows.length === 0) {
+    return {
+      headers: ["result"],
+      rows: [{ result: "" }],
+    };
+  }
+
+  const headers = [...new Set(rows.flatMap((row) => Object.keys(row)))]
+    .filter((key) =>
+      rows.every((row) => isScalar(row[key])),
+    );
+
+  if (headers.length === 0) {
+    return {
+      headers: ["result"],
+      rows: [{ result: "" }],
+    };
+  }
+
+  const scalarRows: ScalarRow[] = rows.map((row) => {
+    const result: ScalarRow = {};
+    for (const [key, rowValue] of Object.entries(row)) {
+      if (isScalar(rowValue)) {
+        result[key] = rowValue;
+      }
+    }
+    return result;
+  });
+
+  return { headers, rows: scalarRows };
+}
+
+export function toMarkdownTable(
+  value: unknown,
+  pretty = false,
+  quoteGuids = false,
+  headerSpec: HeaderSpec = { mode: "default" },
+): string {
+  const { headers, rows } = getScalarRowsAndHeaders(value);
+  const headerDefinitions = headers.map((key, idx) => {
+    let label = key;
+    if (headerSpec.mode === "auto") {
+      label = toAutoHeaderLabel(key);
+    } else if (headerSpec.mode === "list" && headerSpec.labels[idx]) {
+      label = headerSpec.labels[idx];
+    } else if (headerSpec.mode === "map" && headerSpec.map[key]) {
+      label = headerSpec.map[key];
+    }
+    return { key, label };
+  });
+
+  const renderCell = (raw: Scalar): string => {
+    const text = formatCell(raw);
+    return quoteGuids && isGuid(raw) ? `\`${text}\`` : text;
+  };
+
+  if (!pretty) {
+    const headerLine = `| ${headerDefinitions.map((h) => h.label).join(" | ")} |`;
+    const separatorLine = `| ${headerDefinitions.map(() => "---").join(" | ")} |`;
+    const rowLines = rows.map((row) =>
+      `| ${headerDefinitions.map((h) => formatCell(row[h.key])).join(" | ")} |`,
+    );
+    return [headerLine, separatorLine, ...rowLines].join("\n");
+  }
+
+  const widths = headerDefinitions.map((header, idx) =>
+    Math.max(
+      header.label.length,
+      ...rows.map((row) => renderCell(row[headerDefinitions[idx].key]).length),
+    )
+  );
+
+  const renderRow = (values: string[]): string =>
+    `| ${values.map((v, idx) => v.padEnd(widths[idx], " ")).join(" | ")} |`;
+
+  const headerLine = renderRow(headerDefinitions.map((h) => h.label));
+  const separatorLine = `|-${widths.map((w) => "-".repeat(w)).join("-|-")}-|`;
+  const rowLines = rows.map((row) =>
+    renderRow(headerDefinitions.map((header) => renderCell(row[header.key]))),
+  );
+
+  return [headerLine, separatorLine, ...rowLines].join("\n");
+}