#include "kappa/service/service.hpp"
#include "kappa/util.hpp"

#include <format>
#include <sstream>

namespace kappa::service {

std::string generate_runit_service(const ServiceSpec& spec) {
    std::ostringstream out;

    // Shebang
    out << "#!/bin/sh\n";

    // Header
    out << "# Generated by kappa — do not edit manually\n";
    out << std::format("# runit service: {}\n", spec.name);
    out << std::format("# Type: {}\n", spec.type);

    // Forking note
    if (spec.type == "forking") {
        out << "# NOTE: runit requires foreground execution.\n";
        out << "#   If the daemon forks, pass --foreground or equivalent"
               " flag.\n";
    }

    // Oneshot note
    if (spec.type == "oneshot") {
        out << "# NOTE: runit has no native oneshot support. This service"
               " will restart on exit.\n";
    }

    // Redirect stderr to stdout for logging
    out << "exec 2>&1\n";

    // Working directory
    if (!spec.working_dir.empty()) {
        out << std::format("cd \"{}\"\n", util::shell_escape(spec.working_dir));
    }

    // Environment variables
    for (const auto& [key, value] : spec.env) {
        out << std::format("export {}=\"{}\"\n", key, util::shell_escape(value));
    }

    // Final exec — replace the shell with the daemon
    if (!spec.user.empty()) {
        out << std::format("exec chpst -u {} {}\n",
                           util::shell_escape(spec.user), spec.exec);
    } else {
        out << "exec " << spec.exec << "\n";
    }

    return out.str();
}

} // namespace kappa::service