import type { WPConfig } from './config.js';
import {
createCompressionState,
type CompressionOptions,
type CompressionState,
} from './compression/index.js';
/**
* Clamp a text payload to maxResponseKb from config toggles.
* Appends a truncation message when clamped.
*/
export function clampText(text: string, config: WPConfig): string {
const maxBytes = Math.max(1, config.toggles.maxResponseKb) * 1024;
const bytes = byteLength(text);
if (bytes <= maxBytes) return text;
// Trim to ~maxBytes - 512 for headroom, then adjust down to boundary
let limit = Math.max(0, maxBytes - 512);
let out = safeSliceByBytes(text, limit);
const note = `\n\n[Output truncated at ${config.toggles.maxResponseKb}KB. Set WPNAV_MAX_RESPONSE_KB to adjust or refine your query.]`;
// Ensure note fits
const noteBytes = byteLength(note);
if (byteLength(out) + noteBytes > maxBytes) {
out = safeSliceByBytes(out, maxBytes - noteBytes);
}
return out + note;
}
/**
* Format a JSON‑serializable payload using the compression
* infrastructure and clamp it to the configured response limit.
*
* This helper is intended for new tools that want a consistent
* compact/full envelope. Existing tools can continue to use
* clampText directly until they are migrated.
*/
export function formatCompressedJson(
payload: unknown,
config: WPConfig,
options?: CompressionOptions
): { json: string; compression: CompressionState } {
const compression = createCompressionState(config, options);
const envelope = {
_meta: {
mode: compression.mode,
},
data: payload,
};
const json = clampText(JSON.stringify(envelope, null, 2), config);
return { json, compression };
}
function byteLength(s: string): number {
return Buffer.byteLength(s, 'utf8');
}
function safeSliceByBytes(s: string, maxBytes: number): string {
if (maxBytes <= 0) return '';
let bytes = 0;
let i = 0;
while (i < s.length) {
const code = s.codePointAt(i)!;
const encLen = code <= 0x7f ? 1 : code <= 0x7ff ? 2 : code <= 0xffff ? 3 : 4;
if (bytes + encLen > maxBytes) break;
bytes += encLen;
i += code > 0xffff ? 2 : 1;
}
return s.slice(0, i);
}
