/**
 * Bake `migrations/` into a TypeScript module so the migrator can be a single
 * self-contained binary.
 *
 * `drizzle-kit migrate` reads the folder at runtime, which is the right shape
 * on a laptop and the wrong one on a server: the deploy agent ships flat,
 * checksummed files into `bin/`, and a migrator that needs a directory beside
 * it is a migrator that can be run against the wrong directory. Embedding
 * removes the question — the binary *is* the migration set, and its checksum
 * covers every statement it will run.
 *
 * Run before `bun build --compile`. It runs on every build rather than being
 * committed, so the embedded set cannot drift from the folder.
 *
 *   bun run packages/core/scripts/embed-migrations.ts
 */
import crypto from 'node:crypto';
import fs from 'node:fs';
import path from 'node:path';

const here = path.dirname(new URL(import.meta.url).pathname);
const folder = path.join(here, '..', 'migrations');
const out = path.join(here, '..', 'src', 'migrations.generated.ts');

type JournalEntry = { idx: number; when: number; tag: string; breakpoints: boolean };

const journal = JSON.parse(fs.readFileSync(path.join(folder, 'meta', '_journal.json'), 'utf8')) as {
	entries: JournalEntry[];
};

// Deliberately identical to drizzle-orm's own `readMigrationFiles`: the same
// `--> statement-breakpoint` split, the same sha256 over the whole file, the
// same `when` as the ordering key. The live database was migrated by
// drizzle-kit, so anything else here would re-apply migrations that have
// already run.
const migrations = journal.entries.map((e) => {
	const sql = fs.readFileSync(path.join(folder, `${e.tag}.sql`), 'utf8');
	return {
		tag: e.tag,
		sql: sql.split('--> statement-breakpoint'),
		bps: e.breakpoints,
		folderMillis: e.when,
		hash: crypto.createHash('sha256').update(sql).digest('hex')
	};
});

fs.writeFileSync(
	out,
	`// Generated by scripts/embed-migrations.ts. Do not edit.\n` +
		`// ${migrations.length} migrations, ${migrations.at(-1)?.tag ?? 'none'} last.\n` +
		`export type Embedded = {\n` +
		`\ttag: string;\n\tsql: string[];\n\tbps: boolean;\n\tfolderMillis: number;\n\thash: string;\n};\n\n` +
		`export const MIGRATIONS: Embedded[] = ${JSON.stringify(migrations, null, '\t')};\n`
);

console.log(`embedded ${migrations.length} migrations -> ${path.relative(process.cwd(), out)}`);