/**
 * Crypto primitive select codegen.
 *
 * Reads `crypto.config.ts` and, for every registered primitive, writes
 * `packages/universal/crypto-<category>/src/primitives/<id>/<id>.select.ts`
 * as a one-line re-export of `./impl/<id>.<flavour>.js`.
 *
 * The generated file carries a "GENERATED DO NOT EDIT" banner comment.
 * Any hand-edit is detected by `check-crypto-selects.ts` and fails CI.
 */

import { existsSync, mkdirSync, readFileSync, writeFileSync } from "node:fs";
import { dirname, resolve } from "node:path";
import { fileURLToPath } from "node:url";
import { cryptoConfig, type PrimitiveFlavour } from "../crypto.config.js";

// Inlined from @suaveplan/crypto-utils/primitive-id so this script can run
// without needing the crypto-utils package to be built/linked first.
// Must stay in sync with universal/crypto/crypto-utils/src/primitive-id/primitive-id.ts.
const HASH_PRIMITIVE_IDS = [
    "sha256",
    "sha384",
    "sha512",
    "hmac",
    "hkdf",
    "pbkdf2",
    "argon2id",
] as const;
const CURVE_PRIMITIVE_IDS = ["secp256k1", "ed25519", "x25519", "p256"] as const;
const CIPHER_PRIMITIVE_IDS = [
    "aes-256-gcm",
    "chacha20-poly1305",
    "xchacha20-poly1305",
] as const;

type HashId = (typeof HASH_PRIMITIVE_IDS)[number];
type CurveId = (typeof CURVE_PRIMITIVE_IDS)[number];
type CipherId = (typeof CIPHER_PRIMITIVE_IDS)[number];
export type PrimitiveId = HashId | CurveId | CipherId;

function primitiveCategory(id: PrimitiveId): "hash" | "curve" | "cipher" {
    if ((HASH_PRIMITIVE_IDS as readonly string[]).includes(id)) return "hash";
    if ((CURVE_PRIMITIVE_IDS as readonly string[]).includes(id)) return "curve";
    return "cipher";
}

const REPO_ROOT = resolve(dirname(fileURLToPath(import.meta.url)), "..");

export const BANNER =
    "/* GENERATED — DO NOT EDIT. Regenerate with `bun scripts/gen-crypto-selects.ts`. */";

export function selectFileContents(
    id: PrimitiveId,
    flavour: PrimitiveFlavour
): string {
    return `${BANNER}\nexport * from "./impl/${id}.${flavour}.js";\n`;
}

function categoryPackageName(id: PrimitiveId): string {
    const cat = primitiveCategory(id);
    if (cat === "hash") return "crypto-hash";
    if (cat === "curve") return "crypto-curve";
    return "crypto-cipher";
}

export function selectPath(id: PrimitiveId): string {
    const pkg = categoryPackageName(id);
    return resolve(
        REPO_ROOT,
        `universal/auth/${pkg}/src/primitives/${id}/${id}.select.ts`
    );
}

export interface SelectPlan {
    readonly id: PrimitiveId;
    readonly flavour: PrimitiveFlavour;
    readonly path: string;
    readonly contents: string;
}

export function plan(): readonly SelectPlan[] {
    const out: SelectPlan[] = [];
    const allIds = [
        ...HASH_PRIMITIVE_IDS,
        ...CURVE_PRIMITIVE_IDS,
        ...CIPHER_PRIMITIVE_IDS,
    ] as readonly PrimitiveId[];
    for (const id of allIds) {
        const flavour = cryptoConfig[id];
        out.push({
            id,
            flavour,
            path: selectPath(id),
            contents: selectFileContents(id, flavour),
        });
    }
    return out;
}

export function writePlan(plans: readonly SelectPlan[]): readonly {
    readonly path: string;
    readonly action: "written" | "unchanged";
}[] {
    const results: { path: string; action: "written" | "unchanged" }[] = [];
    for (const p of plans) {
        mkdirSync(dirname(p.path), { recursive: true });
        let current: string | undefined;
        if (existsSync(p.path)) {
            current = readFileSync(p.path, "utf8");
        }
        if (current === p.contents) {
            results.push({ path: p.path, action: "unchanged" });
            continue;
        }
        if (current !== undefined && !current.startsWith(BANNER)) {
            throw new Error(
                `Refusing to overwrite hand-edited select file (banner missing): ${p.path}`
            );
        }
        writeFileSync(p.path, p.contents, "utf8");
        results.push({ path: p.path, action: "written" });
    }
    return results;
}

async function main(): Promise<void> {
    const results = writePlan(plan());
    const written = results.filter((r) => r.action === "written").length;
    const unchanged = results.filter((r) => r.action === "unchanged").length;
    console.log(
        `crypto-selects: ${written} written, ${unchanged} unchanged (${results.length} total)`
    );
}

if (import.meta.main) {
    await main();
}