/**
 * File Role Classification for pi-lens
 *
 * Classifies files by their structural role in the project so runners
 * can skip checks that don't apply (e.g. no complexity checks on generated
 * files, no logic-density checks on re-export barrels).
 */

import { basename, dirname } from "node:path";
import { isGeneratedOrArtifact } from "./generated-artifacts.js";

// --- Types ---

export type FileRole =
	| "source" // Regular application source
	| "test" // Test / spec file
	| "init" // Module entry point (index.ts, __init__.py, mod.rs)
	| "re-export" // Pure re-export barrel (only export * / export { } from)
	| "generated" // Auto-generated code — do not lint
	| "config" // Build / tool configuration
	| "stub" // Type-only declaration file (.d.ts or interface-heavy)
	| "migration"; // Database migration

// --- Detection ---

const RE_EXPORT_LINE =
	/^export\s+(type\s+)?\*\s+from\s+|^export\s*\{[^}]*\}\s+from\s+/;

function isReExportBarrel(content: string): boolean {
	const lines = content
		.split(/\r?\n/)
		.map((l) => l.trim())
		.filter(
			(l) =>
				l && !l.startsWith("//") && !l.startsWith("*") && !l.startsWith("/*"),
		);
	return lines.length > 0 && lines.every((l) => RE_EXPORT_LINE.test(l));
}

function isTypeStub(content: string): boolean {
	const lines = content
		.split(/\r?\n/)
		.map((l) => l.trim())
		.filter(
			(l) =>
				l &&
				!l.startsWith("//") &&
				!l.startsWith("*") &&
				!l.startsWith("/*") &&
				l !== "{" &&
				l !== "}",
		);
	if (lines.length < 4) return false;
	const typeOnlyLines = lines.filter(
		(l) =>
			/^(export\s+)?(interface|type|abstract\s+class|declare\s+(class|function|const|var|let|module|namespace|enum))\s+/.test(
				l,
			) ||
			/^(import\s+type\s+|import\s+\{)/.test(l) ||
			/^export\s+type\s+\{/.test(l),
	);
	return typeOnlyLines.length / lines.length >= 0.75;
}

/**
 * Classify the structural role of a file. Pass `content` for higher
 * accuracy (enables generated-code detection, barrel detection, etc.).
 */
export function detectFileRole(filePath: string, content?: string): FileRole {
	const base = basename(filePath).toLowerCase();
	const dir = dirname(filePath).replace(/\\/g, "/").toLowerCase();

	// --- Test ---
	if (
		base.includes(".test.") ||
		base.includes(".spec.") ||
		base.startsWith("test_") ||
		base.startsWith("spec_") ||
		dir.includes("/__tests__/") ||
		dir.includes("/test/") ||
		dir.includes("/tests/") ||
		dir.includes("/spec/") ||
		dir.includes("/specs/") ||
		/[/_-]tests?\/?$/.test(dir) ||
		/[/_-]specs?\/?$/.test(dir)
	)
		return "test";

	// --- Generated/artifact markers (path/name/header-based) ---
	if (
		isGeneratedOrArtifact(filePath, { content, includeDeclarations: false })
	) {
		return "generated";
	}

	// --- Migrations ---
	// Normalize separators before regex so the pattern works on Windows too
	const forwardDir = dir.replace(/\\/g, "/");
	if (
		forwardDir.includes("/migrations/") ||
		forwardDir.includes("/migration/") ||
		/\/\d{4,}_[a-z]/.test(forwardDir + "/" + base)
	)
		return "migration";

	// --- Config ---
	if (
		base.endsWith(".config.ts") ||
		base.endsWith(".config.js") ||
		base.endsWith(".config.mjs") ||
		base.endsWith(".config.cjs") ||
		base === "vite.config.ts" ||
		base === "jest.config.ts" ||
		base === "jest.config.js" ||
		base === "webpack.config.js" ||
		base === "rollup.config.js" ||
		base === "tailwind.config.js" ||
		base === "tailwind.config.ts" ||
		base === "next.config.js" ||
		base === "next.config.mjs"
	)
		return "config";

	// --- Type stubs ---
	if (base.endsWith(".d.ts")) return "stub";
	if (content && isTypeStub(content)) return "stub";

	// --- Init / barrel ---
	const isIndexFile =
		base === "index.ts" ||
		base === "index.tsx" ||
		base === "index.js" ||
		base === "index.mjs" ||
		base === "index.cjs" ||
		base === "index.jsx" ||
		base === "__init__.py" ||
		base === "mod.rs";

	if (isIndexFile) {
		if (content && isReExportBarrel(content)) return "re-export";
		return "init";
	}

	return "source";
}