import { UlwLoopError } from "./types.js";

const PLACEHOLDER_PATTERN = /^(?:placeholder|todo|tbd|n\/a|stub)$/i;

export function invalid(message: string, field: string): never {
	throw new UlwLoopError(message, "ULW_LOOP_QUALITY_GATE_INVALID", { details: { field } });
}

export function isRecord(value: unknown): value is Record<string, unknown> {
	return typeof value === "object" && value !== null && !Array.isArray(value);
}

export function section(value: unknown, field: string): Record<string, unknown> {
	return isRecord(value) ? value : invalid(`Final quality gate is missing ${field} evidence.`, field);
}

export function textField(value: unknown, field: string): string {
	if (typeof value !== "string" || value.trim() === "")
		invalid(`Final quality gate requires non-empty ${field}.`, field);
	const trimmed = value.trim();
	if (PLACEHOLDER_PATTERN.test(trimmed)) invalid(`Final quality gate rejects placeholder ${field}.`, field);
	return trimmed;
}

export function numberField(value: unknown, field: string): number {
	return typeof value === "number" && Number.isFinite(value)
		? value
		: invalid(`Final quality gate requires numeric ${field}.`, field);
}

export function stringArray(value: unknown, field: string): readonly string[] {
	if (!Array.isArray(value) || value.length === 0) return invalid(`Final quality gate requires ${field}.`, field);
	return value.map((item) => textField(item, field));
}

export function emptyBlockers(value: unknown, field: string): readonly [] {
	if (Array.isArray(value) && value.length === 0) return [];
	invalid(`${field} must be empty.`, field);
}

export function literal<T extends string | boolean>(value: unknown, expected: T, field: string): T {
	if (value === expected) return expected;
	invalid(`${field} must be ${String(expected)}.`, field);
}