// SPDX-License-Identifier: LGPL-3.0-only
// SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®

// crafter-debug, the client agents drive an app with. Run is the whole
// program but for the transport: main hands it a Connector that reaches an
// instance over QUIC, and tests hand it one that reaches a Session in the
// same process.
//
// Exit codes:
//   0  done
//   2  a usage error, or no debug build yet (the launcher's stub)
//   3  no instance to talk to
//   4  the app and this client speak different protocols
//   5  timed out
//   6  the app answered with an error
// 1 is left to the launcher and `flatpak run` failing.
export module Crafter.Debug.Cli:Client;
import std;
import Crafter.Debug.Core;

export namespace Crafter::Debug::Cli {
    inline constexpr std::int32_t exitOk = 0;
    inline constexpr std::int32_t exitUsage = 2;
    inline constexpr std::int32_t exitNoInstance = 3;
    inline constexpr std::int32_t exitVersion = 4;
    inline constexpr std::int32_t exitTimeout = 5;
    inline constexpr std::int32_t exitError = 6;

    struct CallError {
        enum class Kind : std::uint8_t {
            // No connection: the app is gone, or its port does not answer.
            Unreachable,
            // Connected, but no reply within the timeout.
            TimedOut,
            // The reply was not what the protocol says.
            Broken,
        };
        Kind kind = Kind::Unreachable;
        std::string message;
    };

    // One request to an instance. The reply is the last object it sends;
    // objects before it are stream lines (`log --follow`), handed to
    // `onLine`, which returns false to stop.
    class Connection {
    public:
        virtual ~Connection() = default;
        virtual std::expected<Value, CallError> Call(const Value& request, std::chrono::milliseconds timeout,
                                                     const std::function<bool(const Value& line)>& onLine) = 0;
    };

    using Connector = std::function<std::unique_ptr<Connection>(const InstanceRecord& instance)>;

    struct Environment {
        Connector connect;
        std::function<std::vector<Instance>()> list = ListInstances;
        std::ostream* out = &std::cout;
        std::ostream* err = &std::cerr;
        // Where a screenshot without -o goes, relative paths included.
        std::filesystem::path cwd = std::filesystem::current_path();
        // The project the launcher that started this client was written for
        // (CRAFTER_DEBUG_PROJECT). Its apps, the ones whose executable lies
        // under it, are picked without -i when other apps run too, and no
        // other app is. Empty: whichever app runs, as long as only one does.
        std::filesystem::path project;
        // Where lldb is here, for the attach command `debugger` prints: its
        // absolute path, since `flatpak enter` runs a command without the
        // sandbox's PATH, which /app/bin is on. Empty for none: gdb then.
        std::function<std::string()> lldb;
    };

    std::int32_t Run(std::span<const std::string_view> args, Environment& environment);

    // The full reference an agent reads with `crafter-debug guide`.
    std::string_view Guide();

    // "30s", "500ms", "2m", "1h"; a bare number is seconds.
    std::optional<std::chrono::milliseconds> ParseDuration(std::string_view text);
}