import { createLogger } from "../utils/logger.js";
const logger = createLogger("usql-mcp:parser");
/**
* Maximum length for extracted error messages (chars)
* This prevents returning massive multi-line error traces
*/
const MAX_ERROR_MESSAGE_LENGTH = 500;
/**
* Regular expressions to detect error lines
*/
const ERROR_PATTERN =
/^.*\b(?:error|ERROR|Error|failed|FAILED|Failed|fatal|FATAL|Fatal|exception|EXCEPTION|Exception)\b/i;
/**
* Patterns for lines that should be skipped (usually not helpful)
*/
const SKIP_PATTERNS = [
/^Context:/i,
/^Hint:/i,
/^Statement:/i,
/^\s*\^/i, // Caret lines pointing to errors
/^Position:/i,
/^Line \d+:/i,
/^\d+ \|/i, // Line numbers from context
/^[a-z_]+=.*$/i, // Variable assignments
/^\s*$/i, // Empty lines
];
/**
* Check if a line should be skipped in error parsing
*/
function shouldSkipLine(line: string): boolean {
return SKIP_PATTERNS.some((pattern) => pattern.test(line));
}
/**
* Parse error messages from usql stderr.
* Extracts the first meaningful error line, handling multi-line errors and context.
* Returns a concise, informative error message.
*/
export function parseUsqlError(stderr: string): string {
logger.debug("[parser] Parsing usql error");
if (!stderr || typeof stderr !== "string") {
return "Unknown error";
}
// Split into lines and filter out empty/skip lines
const lines = stderr.split("\n").filter((line) => !shouldSkipLine(line));
if (lines.length === 0) {
return "Unknown error";
}
// First pass: find a line matching error pattern
for (const line of lines) {
if (ERROR_PATTERN.test(line)) {
const trimmed = line.trim();
// Limit message length
return trimmed.length > MAX_ERROR_MESSAGE_LENGTH
? trimmed.substring(0, MAX_ERROR_MESSAGE_LENGTH) + "..."
: trimmed;
}
}
// Second pass: return first non-empty, non-skipped line
const firstMeaningfulLine = lines[0]?.trim();
if (firstMeaningfulLine) {
return firstMeaningfulLine.length > MAX_ERROR_MESSAGE_LENGTH
? firstMeaningfulLine.substring(0, MAX_ERROR_MESSAGE_LENGTH) + "..."
: firstMeaningfulLine;
}
// Fallback: return original stderr up to max length
const fallback = stderr.trim();
return fallback.length > MAX_ERROR_MESSAGE_LENGTH
? fallback.substring(0, MAX_ERROR_MESSAGE_LENGTH) + "..."
: fallback;
}
