import childProcess from "node:child_process";
import fs from "node:fs";
import path from "node:path";
import { fromBinary, toJsonString } from "@bufbuild/protobuf";
import type { PackageDescriptor } from "./gen/quixos/package_pb.js";
import { PackageDescriptorSchema } from "./gen/quixos/package_pb.js";

const protoPaths = () => {
  const candidates = [
    ...(process.env.QUIXOS_PROTO_PATH ?? "")
      .split(path.delimiter)
      .map((entry) => entry.trim())
      .filter(Boolean),
    path.resolve(process.cwd(), "proto"),
    path.resolve(process.cwd(), "quixos-protocol/proto"),
  ];
  return [...new Set(candidates)].filter((candidate) => fs.existsSync(path.join(candidate, "quixos/package.proto")));
};

export const parsePackageDescriptorTextproto = (text: string): PackageDescriptor => {
  const paths = protoPaths();
  if (paths.length === 0) {
    throw new Error("QUIXOS_PROTO_PATH must include quixos-protocol/proto to parse package descriptors");
  }
  const result = childProcess.spawnSync(
    "protoc",
    [
      ...paths.map((protoPath) => `--proto_path=${protoPath}`),
      "--encode=quixos.PackageDescriptor",
      "quixos/package.proto",
    ],
    {
      input: Buffer.from(text),
      maxBuffer: 1024 * 1024 * 8,
    },
  );
  if (result.error) {
    throw result.error;
  }
  if (result.status !== 0) {
    throw new Error(`Failed to parse package descriptor textproto:\n${result.stderr.toString().trim()}`);
  }
  return fromBinary(PackageDescriptorSchema, result.stdout);
};

export const packageDescriptorToJson = (descriptor: PackageDescriptor) =>
  toJsonString(PackageDescriptorSchema, descriptor, {
    prettySpaces: 2,
  });

export const validatePackageDescriptor = (descriptor: PackageDescriptor): string[] => {
  const errors: string[] = [];
  if (!descriptor.packageId) {
    errors.push("packageId is required");
  }
  if (!descriptor.packageRevisionId) {
    errors.push("packageRevisionId is required");
  }
  if (!descriptor.runtimeProtocolVersion) {
    errors.push("runtimeProtocolVersion is required");
  }
  const seenExports = new Set<string>();
  for (const [index, entry] of descriptor.exports.entries()) {
    if (!entry.exportId) errors.push(`exports[${index}].exportId is required`);
    if (!entry.runtimeSymbol) {
      errors.push(`exports[${index}].runtimeSymbol is required`);
    }
    if (seenExports.has(entry.exportId)) {
      errors.push(`duplicate export: ${entry.exportId}`);
    }
    seenExports.add(entry.exportId);
  }

  return errors;
};