#include "kappa/service/service.hpp"

#include <filesystem>
#include <format>
#include <fstream>

namespace kappa::service {

// ---------------------------------------------------------------------------
// Backend service-file generators (defined in separate .cpp files)
// systemd_service and s6_service are declared in service.hpp
// ---------------------------------------------------------------------------

// ---------------------------------------------------------------------------
// ServiceSpec::from_service_init
// ---------------------------------------------------------------------------

ServiceSpec ServiceSpec::from_service_init(const dsl::NamedService& ns) {
    ServiceSpec spec;
    spec.name = ns.name;
    spec.description = ns.description;
    spec.exec = ns.exec;
    spec.user = ns.user;
    spec.ports = ns.ports;
    spec.env = ns.env;
    spec.after = ns.after;
    spec.working_dir = ns.working_dir;

    // Normalize type
    if (ns.type == "forking" || ns.type == "longrun" ||
        ns.type == "notify" || ns.type == "oneshot") {
        spec.type = ns.type;
    } else {
        spec.type = "simple";
    }

    // Restart policy
    spec.restart_policy = ns.restart;
    if (spec.restart_policy.empty() && ns.type == "longrun") {
        spec.restart_policy = "always";
    }

    return spec;
}

// ---------------------------------------------------------------------------
// generate_service_file — dispatch to the correct backend
// ---------------------------------------------------------------------------

std::string generate_service_file(InitSystem is, const ServiceSpec& spec) {
    switch (is) {
    case InitSystem::Systemd:
        return generate_systemd_service(spec);
    case InitSystem::OpenRC:
        return generate_openrc_service(spec);
    case InitSystem::S6:
        return generate_s6_service(spec);
    case InitSystem::Dinit:
        return generate_dinit_service(spec);
    case InitSystem::Runit:
        return generate_runit_service(spec);
    case InitSystem::Unknown:
    default:
        return {};
    }
}

// ---------------------------------------------------------------------------
// install_service — write the generated file(s) to disk
// ---------------------------------------------------------------------------

ServiceInstallResult install_service(InitSystem is,
                                     const ServiceSpec& spec,
                                     std::string_view prefix) {
    namespace fs = std::filesystem;

    auto paths = init_paths(is, prefix);
    if (paths.service_dir.empty()) {
        return {false, {}, "Unknown init system"};
    }

    std::error_code ec;

    // ---- S6: directory-based layout (type + run) ----
    // S6: directory-based layout. Content generated inline rather than
    // calling generate_s6_service() to avoid parsing the combined output.
    if (is == InitSystem::S6) {
        fs::path svc_dir = fs::path(paths.service_dir) / spec.name;
        fs::create_directories(svc_dir, ec);
        if (ec) {
            return {false, {}, ec.message()};
        }

        // --- type file ---
        {
            fs::path type_path = svc_dir / "type";
            std::ofstream out(type_path);
            if (!out) {
                return {false, {},
                        std::format("Failed to write {}", type_path.string())};
            }
            out << ((spec.type == "oneshot") ? "oneshot" : "longrun");
        }

        // --- run file ---
        fs::path run_path = svc_dir / "run";
        {
            std::ofstream out(run_path);
            if (!out) {
                return {false, {},
                        std::format("Failed to write {}", run_path.string())};
            }
            out << s6_execline_shebang;
            out << "# Generated by kappa — do not edit manually\n";
            out << std::format("# s6 service: {}\n", spec.name);
            if (!spec.working_dir.empty()) {
                out << std::format("cd {}\n", spec.working_dir);
            }
            for (const auto& [key, value] : spec.env) {
                out << std::format("export {} \"{}\"\n", key, value);
            }
            if (!spec.user.empty()) {
                out << std::format("s6-setuidgid {}\n", spec.user);
            }
            out << spec.exec << "\n";
        }

        // Make run file executable
        fs::permissions(run_path,
                        fs::perms::owner_exec | fs::perms::group_exec |
                            fs::perms::others_exec,
                        fs::perm_options::add, ec);

        return {true, svc_dir.string(), {}};
    }

    // ---- Runit: directory-based layout (run) ----
    if (is == InitSystem::Runit) {
        fs::path svc_dir = fs::path(paths.service_dir) / spec.name;
        fs::create_directories(svc_dir, ec);
        if (ec) {
            return {false, {}, ec.message()};
        }

        fs::path run_path = svc_dir / "run";
        {
            std::ofstream out(run_path);
            if (!out) {
                return {false, {},
                        std::format("Failed to write {}", run_path.string())};
            }
            out << generate_runit_service(spec);
        }

        // Make run executable
        fs::permissions(run_path,
                        fs::perms::owner_exec | fs::perms::group_exec |
                            fs::perms::others_exec,
                        fs::perm_options::add, ec);

        return {true, svc_dir.string(), {}};
    }

    // ---- Systemd / OpenRC / Dinit: single service file ----
    std::string content = generate_service_file(is, spec);
    if (content.empty()) {
        return {false, {}, "Failed to generate service file for init system"};
    }

    // Determine filename
    std::string filename;
    switch (is) {
    case InitSystem::Systemd:
        filename = std::format("{}.service", spec.name);
        break;
    case InitSystem::OpenRC:
    case InitSystem::Dinit:
        filename = spec.name;
        break;
    default:
        return {false, {}, "Unknown init system"};
    }

    fs::path file_path = fs::path(paths.service_dir) / filename;
    fs::create_directories(file_path.parent_path(), ec);
    if (ec) {
        return {false, {}, ec.message()};
    }

    {
        std::ofstream out(file_path);
        if (!out) {
            return {false, {},
                    std::format("Failed to write {}", file_path.string())};
        }
        out << content;
    }

    // Dinit: also write companion .env file
    if (is == InitSystem::Dinit && !spec.env.empty()) {
        fs::path env_path = fs::path(paths.service_dir) / std::format("{}.env", spec.name);
        std::ofstream env_out(env_path);
        if (env_out) {
            for (const auto& [key, value] : spec.env) {
                env_out << key << "=" << value << "\n";
            }
        }
    }

    return {true, file_path.string(), {}};
}

} // namespace kappa::service