/**
 * Filters CHANGED_FILES to a single package and detects config-file bailouts.
 * Output is a shell sentinel (SKIP / RUN_FULL / file list). The actual
 * import-graph walk is the runner's job (jest --findRelatedTests / vitest
 * related).
 */

import { existsSync } from 'node:fs';
import { isAbsolute, relative, resolve } from 'node:path';

import { matchesGlobalTrigger } from './global-triggers.js';
import { toPosix } from './path-utils.js';

export type Runner = 'jest' | 'vitest';
/**
 * Jest has two test surfaces in this workspace:
 *   - unit       — pure modules + mocked deps; only the unit bailouts apply
 *   - integration — HTTP / DI container; transitive deps that don't appear in
 *                   the import graph (db schema, shared fixtures, migrations)
 *                   force RUN_FULL. See JEST_INTEGRATION_BAILOUT for the list.
 * `undefined` collapses to the unit variant for callers that don't specify.
 */
export type JestVariant = 'unit' | 'integration';

// Bailout patterns are centralised here (vs the original DEVP-194 spec's
// per-package `n8nTestChanged.inPackageBailouts` field) because the n8n
// workspace shares the same vitest config helpers + setup file layout via
// @n8n/vitest-config. If a package ever needs a custom bailout that doesn't
// fit these patterns, switch to per-package config rather than expanding
// these any further.
const COMMON_BAILOUT = [
	/^package\.json$/,
	/^tsconfig(\..+)?\.json$/,
	/^\.swcrc$/,
	/^babel\.config\.[cm]?[jt]s$/,
];
const JEST_BAILOUT = [
	...COMMON_BAILOUT,
	/^jest\.config\.[cm]?[jt]s$/,
	/(?:^|\/)(?:jest|test)\.setup\.[cm]?[jt]s$/,
	/(?:^|\/)__tests__\/setup\.[cm]?[jt]s$/,
];
// Integration tests hit HTTP + the DI container, so changes to types that
// aren't import-graph-visible to the test file still flow through at runtime:
//   - entity / repository changes — touched at runtime via `Container.get`,
//     not imported by the test
//   - migrations — never imported but every integration test depends on the
//     resulting schema
//   - `src/databases/**` / `src/modules/*/database/**` — schema scaffolding
//   - `test/integration/shared/**` — shared fixtures coupled at runtime
//   - `test/migration/**` — migration test infrastructure
// Without these, jest --findRelatedTests would return zero tests and CI
// would falsely report green on changes that genuinely break integration.
const JEST_INTEGRATION_BAILOUT = [
	...JEST_BAILOUT,
	/\.entity\.[cm]?ts$/,
	/\.repository\.[cm]?ts$/,
	/\.migration\.[cm]?ts$/,
	/^src\/databases\//,
	/^src\/modules\/[^/]+\/database\//,
	/^test\/integration\/shared\//,
	/^test\/migration\//,
];
// Frontend packages use vite.config.* for the vitest config too (vitest reads
// vite.config). Setup files live at src/__tests__/setup.ts per the shared
// @n8n/vitest-config convention.
const VITEST_BAILOUT = [
	...COMMON_BAILOUT,
	/^vite\.config\.[cm]?[jt]s$/,
	/^vitest\.config\.[cm]?[jt]s$/,
	/(?:^|\/)vitest\.setup\.[cm]?[jt]s$/,
	/(?:^|\/)__tests__\/setup\.[cm]?[jt]s$/,
];

export interface ComputeScopeOptions {
	runner: Runner;
	packageDir: string;
	rootDir: string;
	/** `null` = no signal → RUN_FULL (local dev with unset env). */
	changedFiles: string[] | null;
	/**
	 * Only relevant when `runner === 'jest'`. Selects the bailout set:
	 * `'integration'` widens it to catch runtime-coupled changes (entities,
	 * repositories, migrations, shared fixtures). Defaults to `'unit'`.
	 */
	jestVariant?: JestVariant;
}

export type ScopeResult =
	| { kind: 'skip'; reason: string }
	| { kind: 'full'; reason: string; trigger?: string }
	| { kind: 'scoped'; files: string[] };

export function computeScope(options: ComputeScopeOptions): ScopeResult {
	if (options.changedFiles === null) {
		return { kind: 'full', reason: 'No CHANGED_FILES signal (local dev)' };
	}

	// Workspace-wide triggers (lockfile, root manifest, universal sinks like
	// @n8n/db / workflow / core) force RUN_FULL regardless of which package we
	// are scoping. The dep-graph in affected-packages lists the package as
	// affected, but the in-package filter below would otherwise SKIP it because
	// the trigger file lives outside the package — a silent false green.
	const globalTrigger = options.changedFiles.find(matchesGlobalTrigger);
	if (globalTrigger) {
		return { kind: 'full', reason: 'Global trigger changed', trigger: globalTrigger };
	}

	const absolute = isAbsolute(options.packageDir)
		? options.packageDir
		: resolve(options.rootDir, options.packageDir);
	if (!existsSync(absolute)) throw new Error(`Package directory not found: ${absolute}`);
	const pkgPrefix = toPosix(relative(options.rootDir, absolute));
	const pkgPrefixSlash = `${pkgPrefix}/`;

	const inPackage = options.changedFiles.filter(
		(f) => f === pkgPrefix || f.startsWith(pkgPrefixSlash),
	);
	if (inPackage.length === 0) return { kind: 'skip', reason: 'No changed files in package' };

	const bailout =
		options.runner === 'jest'
			? options.jestVariant === 'integration'
				? JEST_INTEGRATION_BAILOUT
				: JEST_BAILOUT
			: VITEST_BAILOUT;
	for (const file of inPackage) {
		const relInPkg = file.slice(pkgPrefixSlash.length);
		if (bailout.some((p) => p.test(relInPkg))) {
			return { kind: 'full', reason: 'Config or package-level file changed', trigger: file };
		}
	}

	return { kind: 'scoped', files: inPackage };
}

export function formatScope(result: ScopeResult): string {
	switch (result.kind) {
		case 'skip':
			return 'SKIP';
		case 'full':
			return 'RUN_FULL';
		case 'scoped':
			return result.files.join(' ');
	}
}