import { existsSync, readdirSync, readFileSync } from "node:fs";
import { dirname, join } from "node:path";
import { fileURLToPath } from "node:url";

// Locate the shared cairnq-protocol dir. Resolution: $CAIRNQ_PROTOCOL_DIR -> walk
// up to `cairnq-protocol/` (monorepo dev) -> vendored `_protocol/` next to this
// module (written at publish time). Both SDKs load the SAME .sql strings
// (zero-drift guarantee). The dir is laid out per-dialect (sql/<dialect>/*.sql,
// migrations/<dialect>/*.sql) so a second backend (Postgres) slots in beside
// sqlite; `dialect` picks the subtree.
//
// The source tree wins over the vendored copy on purpose: vendoring is a publish
// step that also runs locally, and a stale `_protocol/` shadowing the canonical
// SQL means edits to cairnq-protocol/ are silently not under test. An installed
// package has no repo above it, so it falls through to the vendored copy.
export function findProtocolRoot(): string {
  const env = process.env.CAIRNQ_PROTOCOL_DIR;
  if (env) return env;
  const start = dirname(fileURLToPath(import.meta.url));
  let dir = start;
  for (let i = 0; i < 10; i++) {
    const candidate = join(dir, "cairnq-protocol");
    if (existsSync(join(candidate, "sql"))) return candidate;
    const parent = dirname(dir);
    if (parent === dir) break;
    dir = parent;
  }
  const vendored = join(start, "_protocol");
  if (existsSync(join(vendored, "sql"))) return vendored;
  throw new Error("cannot locate cairnq-protocol; set CAIRNQ_PROTOCOL_DIR");
}

export function loadStatements(
  dialect = "sqlite",
  root = findProtocolRoot(),
): Record<string, string> {
  const dir = join(root, "sql", dialect);
  const out: Record<string, string> = {};
  for (const file of readdirSync(dir).sort()) {
    if (file.endsWith(".sql")) {
      out[file.slice(0, -4)] = readFileSync(join(dir, file), "utf-8");
    }
  }
  return out;
}

export function loadMigrations(
  dialect = "sqlite",
  root = findProtocolRoot(),
): { name: string; sql: string }[] {
  const dir = join(root, "migrations", dialect);
  return readdirSync(dir)
    .filter((f) => f.endsWith(".sql"))
    .sort()
    .map((f) => ({ name: f, sql: readFileSync(join(dir, f), "utf-8") }));
}