module;

#include <toml.hpp>

module cargoxx.codegen;

import std;
import cargoxx.util;

namespace cargoxx::codegen {

auto parse_vendor_toml(std::string_view body) -> util::Result<VendorIndex> {
    toml::table root;
    try {
        root = toml::parse(body);
    } catch (const toml::parse_error& e) {
        return std::unexpected(util::Error{
            util::ErrorCode::ManifestParseError,
            std::format("vendor.toml is not valid TOML: {}", e.description()),
            "", std::nullopt, std::nullopt,
        });
    }

    auto missing = [](std::string msg) {
        return util::Error{
            util::ErrorCode::ManifestInvalidField, std::move(msg), "",
            std::nullopt, std::nullopt,
        };
    };

    VendorIndex out;
    if (const auto* tbl = root["nixpkgs"].as_table()) {
        if (auto v = (*tbl)["store_path"].value<std::string>()) {
            out.nixpkgs_store_path = *v;
        } else {
            return std::unexpected(missing("vendor.toml: [nixpkgs].store_path is required"));
        }
    } else {
        return std::unexpected(missing("vendor.toml: [nixpkgs] table is required"));
    }
    if (const auto* tbl = root["flake_utils"].as_table()) {
        if (auto v = (*tbl)["store_path"].value<std::string>()) {
            out.flake_utils_store_path = *v;
        } else {
            return std::unexpected(missing("vendor.toml: [flake_utils].store_path is required"));
        }
    } else {
        return std::unexpected(missing("vendor.toml: [flake_utils] table is required"));
    }

    if (const auto* arr = root["dep"].as_array()) {
        for (const auto& el : *arr) {
            const auto* tbl = el.as_table();
            if (!tbl) {
                return std::unexpected(missing("vendor.toml: [[dep]] entries must be tables"));
            }
            auto attr = (*tbl)["nixpkgs_attr"].value<std::string>();
            auto path = (*tbl)["store_path"].value<std::string>();
            if (!attr || !path) {
                return std::unexpected(missing(
                    "vendor.toml: each [[dep]] needs nixpkgs_attr and store_path"));
            }
            out.dep_store_paths.emplace(*attr, *path);
        }
    }
    return out;
}

} // namespace cargoxx::codegen