#include "commands.hh"

#include "buffer.hh"
#include "buffer_manager.hh"
#include "buffer_utils.hh"
#include "client.hh"
#include "client_manager.hh"
#include "color_registry.hh"
#include "command_manager.hh"
#include "completion.hh"
#include "context.hh"
#include "debug.hh"
#include "event_manager.hh"
#include "file.hh"
#include "highlighter.hh"
#include "highlighters.hh"
#include "option_manager.hh"
#include "option_types.hh"
#include "parameters_parser.hh"
#include "register_manager.hh"
#include "remote.hh"
#include "shell_manager.hh"
#include "string.hh"
#include "user_interface.hh"
#include "utf8_iterator.hh"
#include "window.hh"

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

namespace Kakoune
{

namespace
{

Buffer* open_or_create(const String& filename, Context& context)
{
    Buffer* buffer = create_buffer_from_file(filename);
    if (not buffer)
    {
        context.print_status({ "new file " + filename, get_color("StatusLine") });
        buffer = new Buffer(filename, Buffer::Flags::File | Buffer::Flags::New);
    }
    return buffer;
}

Buffer* open_fifo(const String& name , const String& filename, bool scroll)
{
    int fd = open(parse_filename(filename).c_str(), O_RDONLY);
    fcntl(fd, F_SETFD, FD_CLOEXEC);
    if (fd < 0)
       throw runtime_error("unable to open " + filename);

    BufferManager::instance().delete_buffer_if_exists(name);

    return create_fifo_buffer(std::move(name), fd, scroll);
}

const PerArgumentCommandCompleter filename_completer({
     [](const Context& context, CompletionFlags flags, const String& prefix, ByteCount cursor_pos)
     { return Completions{ 0_byte, prefix.length(),
                           complete_filename(prefix,
                                             context.options()["ignored_files"].get<Regex>(),
                                             cursor_pos) }; }
});

const PerArgumentCommandCompleter buffer_completer({
    [](const Context& context, CompletionFlags flags, const String& prefix, ByteCount cursor_pos)
    { return Completions{ 0_byte, prefix.length(),
                          BufferManager::instance().complete_buffer_name(prefix, cursor_pos) }; }
});

const ParameterDesc no_params{
    SwitchMap{}, ParameterDesc::Flags::None, 0, 0
};

const ParameterDesc single_name_param{
    SwitchMap{}, ParameterDesc::Flags::None, 1, 1
};

const ParameterDesc single_optional_name_param{
    SwitchMap{}, ParameterDesc::Flags::None, 0, 1
};

struct CommandDesc
{
    const char* name;
    const char* alias;
    const char* docstring;
    ParameterDesc params;
    CommandFlags flags;
    CommandCompleter completer;
    void (*func)(const ParametersParser&, Context&);
};

template<bool force_reload>
void edit(const ParametersParser& parser, Context& context)
{
    const String name = parser[0];

    Buffer* buffer = nullptr;
    if (not force_reload)
        buffer = BufferManager::instance().get_buffer_ifp(name);
    if (not buffer)
    {
        if (parser.has_option("scratch"))
        {
            BufferManager::instance().delete_buffer_if_exists(name);
            buffer = new Buffer(name, Buffer::Flags::None);
        }
        else if (parser.has_option("fifo"))
            buffer = open_fifo(name, parser.option_value("fifo"), parser.has_option("scroll"));
        else
            buffer = open_or_create(name, context);
    }

    BufferManager::instance().set_last_used_buffer(*buffer);

    const size_t param_count = parser.positional_count();
    if (buffer != &context.buffer() or param_count > 1)
        context.push_jump();

    if (buffer != &context.buffer())
        context.change_buffer(*buffer);

    if (param_count > 1 and not parser[1].empty())
    {
        int line = std::max(0, str_to_int(parser[1]) - 1);
        int column = param_count > 2 and not parser[2].empty() ?
                     std::max(0, str_to_int(parser[2]) - 1) : 0;

        context.selections() = context.buffer().clamp({ line,  column });
        if (context.has_window())
            context.window().center_line(context.selections().main().cursor().line);
    }
}

ParameterDesc edit_params{
    SwitchMap{ { "scratch", { false, "create a scratch buffer, not linked to a file" } },
               { "fifo", { true, "create a buffer reading its content from a named fifo" } },
               { "scroll", { false, "place the initial cursor so that the fifo will scroll to show new data" } } },
    ParameterDesc::Flags::None, 1, 3
};

const CommandDesc edit_cmd = {
    "edit",
    "e",
    "edit <switches> <filename>: open the given filename in a buffer",
    edit_params,
    CommandFlags::None,
    filename_completer,
    edit<false>
};

const CommandDesc force_edit_cmd = {
    "edit!",
    "e!",
    "edit! <switches> <filename>: open the given filename in a buffer, force reload if needed",
    edit_params,
    CommandFlags::None,
    filename_completer,
    edit<true>
};

void write_buffer(const ParametersParser& parser, Context& context)
{
    Buffer& buffer = context.buffer();

    if (parser.positional_count() == 0 and !(buffer.flags() & Buffer::Flags::File))
        throw runtime_error("cannot write a non file buffer without a filename");

    String filename = parser.positional_count() == 0 ? buffer.name()
                                     : parse_filename(parser[0]);

    write_buffer_to_file(buffer, filename);
}

const CommandDesc write_cmd = {
    "write",
    "w",
    "write [filename]: write the current buffer to it's file or to [filename] if specified",
    single_optional_name_param,
    CommandFlags::None,
    filename_completer,
    write_buffer,
};

const CommandDesc writeall_cmd = {
    "writeall",
    "wa",
    "write all buffers that are associated to a file",
    no_params,
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        for (auto& buffer : BufferManager::instance())
        {
            if ((buffer->flags() & Buffer::Flags::File) and buffer->is_modified())
                write_buffer_to_file(*buffer, buffer->name());
        }
    }
};

template<bool force>
void quit(const ParametersParser& parser, Context& context)
{
    if (not force and ClientManager::instance().count() == 1)
    {
        std::vector<String> names;
        for (auto& buffer : BufferManager::instance())
        {
            if ((buffer->flags() & Buffer::Flags::File) and buffer->is_modified())
                names.push_back(buffer->name());
        }
        if (not names.empty())
        {
            String message = "modified buffers remaining: [";
            for (auto it = names.begin(); it != names.end(); ++it)
            {
                if (it != names.begin())
                    message += ", ";
                message += *it;
            }
            message += "]";
            throw runtime_error(message);
        }
    }
    // unwind back to this client event handler.
    throw client_removed{};
}

const CommandDesc quit_cmd = {
    "quit",
    "q",
    "quit current client, and the kakoune session if the client is the last (if not running in daemon mode)",
    no_params,
    CommandFlags::None,
    CommandCompleter{},
    quit<false>
};

const CommandDesc force_quit_cmd = {
    "quit!",
    "q!",
    "quit current client, and the kakoune session if the client is the last (if not running in daemon mode)\n"
    "force quit even if the client is the last and some buffers are not saved.",
    no_params,
    CommandFlags::None,
    CommandCompleter{},
    quit<true>
};

const CommandDesc write_quit_cmd = {
    "wq",
    nullptr,
    "write current buffer and quit current client",
    no_params,
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        write_buffer(parser, context);
        quit<false>(ParametersParser{memoryview<String>{}, no_params}, context);
    }
};

const CommandDesc force_write_quit_cmd = {
    "wq!",
    nullptr,
    "write current buffer and quit current client, even if other buffers are not saved",
    no_params,
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        write_buffer(parser, context);
        quit<true>(ParametersParser{memoryview<String>{}, no_params}, context);
    }
};

const CommandDesc buffer_cmd = {
    "buffer",
    "b",
    "buffer <name>: set buffer to edit in current client",
    single_name_param,
    CommandFlags::None,
    buffer_completer,
    [](const ParametersParser& parser, Context& context)
    {
        Buffer& buffer = BufferManager::instance().get_buffer(parser[0]);
        BufferManager::instance().set_last_used_buffer(buffer);

        if (&buffer != &context.buffer())
        {
            context.push_jump();
            context.change_buffer(buffer);
        }
    }
};

template<bool force>
void delete_buffer(const ParametersParser& parser, Context& context)
{
    BufferManager& manager = BufferManager::instance();
    Buffer& buffer = parser.positional_count() == 0 ? context.buffer() : manager.get_buffer(parser[0]);
    if (not force and (buffer.flags() & Buffer::Flags::File) and buffer.is_modified())
        throw runtime_error("buffer " + buffer.name() + " is modified");

    if (manager.count() == 1)
        throw runtime_error("buffer " + buffer.name() + " is the last one");

    manager.delete_buffer(buffer);
}

const CommandDesc delbuf_cmd = {
    "delbuf",
    "db",
    "delbuf [name]: delete the current buffer or the buffer named <name> if given",
    single_optional_name_param,
    CommandFlags::None,
    buffer_completer,
    delete_buffer<false>
};

const CommandDesc force_delbuf_cmd = {
    "delbuf!",
    "db!",
    "delbuf! [name]: delete the current buffer or the buffer named <name> if given, even if the buffer is unsaved",
    single_optional_name_param,
    CommandFlags::None,
    buffer_completer,
    delete_buffer<false>
};

const CommandDesc namebuf_cmd = {
    "namebuf",
    nullptr,
    "namebuf <name>: change current buffer name",
    single_name_param,
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        if (not context.buffer().set_name(parser[0]))
            throw runtime_error("unable to change buffer name to " + parser[0]);
    }
};

const CommandDesc define_highlighter_cmd = {
    "defhl",
    "dh",
    "defhl <name>: define a new reusable highlighter",
    single_name_param,
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        const String& name = parser[0];
        DefinedHighlighters::instance().append({name, HighlighterGroup{}});
    }
};

template<typename GetRootGroup>
CommandCompleter group_rm_completer(GetRootGroup get_root_group)
{
    return [=](const Context& context, CompletionFlags flags,
               CommandParameters params, size_t token_to_complete,
               ByteCount pos_in_token) -> Completions {
        auto& root_group = get_root_group(context);
        const String& arg = params[token_to_complete];
        if (token_to_complete == 1 and params[0] == "-group")
            return { 0_byte, arg.length(), root_group.complete_group_id(arg, pos_in_token) };
        else if (token_to_complete == 2 and params[0] == "-group")
            return { 0_byte, arg.length(), root_group.get_group(params[1], '/').complete_id(arg, pos_in_token) };
        return { 0_byte, arg.length(), root_group.complete_id(arg, pos_in_token) };
    };
}

template<typename FactoryRegistry, typename GetRootGroup>
CommandCompleter group_add_completer(GetRootGroup get_root_group)
{
    return [=](const Context& context, CompletionFlags flags,
               CommandParameters params, size_t token_to_complete,
               ByteCount pos_in_token) -> Completions {
        auto& root_group = get_root_group(context);
        const String& arg = params[token_to_complete];
        if (token_to_complete == 1 and params[0] == "-group")
            return { 0_byte, arg.length(), root_group.complete_group_id(arg, pos_in_token) };
        else if (token_to_complete == 0 or (token_to_complete == 2 and params[0] == "-group"))
            return { 0_byte, arg.length(), FactoryRegistry::instance().complete_name(arg, pos_in_token) };
        return Completions{};
    };
}

HighlighterGroup& get_highlighters(const Context& c) { return c.window().highlighters(); }

const CommandDesc add_highlighter_cmd = {
    "addhl",
    "ah",
    "addhl <switches> <type> <type params>...: add an highlighter to current window",
    ParameterDesc{
        SwitchMap{ { "group", { true, "add highlighter to named group" } },
                   { "def-group", { true, "add highlighter to reusable defined group" } } },
        ParameterDesc::Flags::SwitchesOnlyAtStart, 1
    },
    CommandFlags::None,
    group_add_completer<HighlighterRegistry>(get_highlighters),
    [](const ParametersParser& parser, Context& context)
    {
        HighlighterRegistry& registry = HighlighterRegistry::instance();

        auto begin = parser.begin();
        const String& name = *begin;
        std::vector<String> highlighter_params;
        for (++begin; begin != parser.end(); ++begin)
            highlighter_params.push_back(*begin);

        if (parser.has_option("group") and parser.has_option("def-group"))
            throw runtime_error("-group and -def-group cannot be specified together");

        HighlighterGroup* group = nullptr;

        if (parser.has_option("def-group"))
            group = &DefinedHighlighters::instance().get_group(parser.option_value("def-group"), '/');
        else
        {
            HighlighterGroup& window_hl = context.window().highlighters();
            group = parser.has_option("group") ?
                    &window_hl.get_group(parser.option_value("group"), '/')
                  : &window_hl;
        }

        group->append(registry[name](highlighter_params));
    }
};

const CommandDesc rm_highlighter_cmd = {
    "rmhl",
    "rh",
    "rmhl <switches> <name>: remove highlighter <name> from current window",
    ParameterDesc{
        SwitchMap{ { "group", { true, "remove highlighter from given group" } } },
        ParameterDesc::Flags::None, 1, 1
    },
    CommandFlags::None,
    group_rm_completer(get_highlighters),
    [](const ParametersParser& parser, Context& context)
    {
        HighlighterGroup& window_hl = context.window().highlighters();
        HighlighterGroup& group = parser.has_option("group") ?
            window_hl.get_group(parser.option_value("group"), '/')
          : window_hl;

        group.remove(parser[0]);
    }
};

HookManager& get_hook_manager(const String& scope, Context& context)
{
    if (prefix_match("global", scope))
        return GlobalHooks::instance();
    else if (prefix_match("buffer", scope))
        return context.buffer().hooks();
    else if (prefix_match("window", scope))
        return context.window().hooks();
    throw runtime_error("error: no such hook container " + scope);
}

CandidateList complete_scope(StringView prefix)
{
    CandidateList res;
    for (auto scope : { "global", "buffer", "window" })
    {
        if (prefix_match(scope, prefix))
            res.emplace_back(scope);
    }
    return res;
}

const CommandDesc add_hook_cmd = {
    "hook",
    nullptr,
    "hook <switches> <scope> <hook_name> <command>: add <command> to be executed on hook <hook_name> in <scope> context",
    ParameterDesc{
        SwitchMap{ { "id", { true, "set hook id" } } },
        ParameterDesc::Flags::None, 4, 4
    },
    CommandFlags::None,
    [](const Context& context, CompletionFlags flags,
       CommandParameters params, size_t token_to_complete, ByteCount pos_in_token)
    {
        if (token_to_complete == 0)
            return Completions{ 0_byte, params[0].length(),
                                complete_scope(params[0].substr(0_byte, pos_in_token)) };
        else if (token_to_complete == 3)
        {
            auto& cm = CommandManager::instance();
            return cm.complete(context, flags, params[3], pos_in_token);
        }
        return Completions{};
    },
    [](const ParametersParser& parser, Context& context)
    {
        // copy so that the lambda gets a copy as well
        Regex regex(parser[2].begin(), parser[2].end());
        String command = parser[3];
        auto hook_func = [=](const String& param, Context& context) {
            if (boost::regex_match(param.begin(), param.end(), regex))
                CommandManager::instance().execute(command, context, {},
                                                   { { "hook_param", param } });
        };
        String id = parser.has_option("id") ? parser.option_value("id") : "";
        get_hook_manager(parser[0], context).add_hook(parser[1], id, hook_func);
    }
};

const CommandDesc rm_hook_cmd = {
    "rmhooks",
    nullptr,
    "rmhooks <id>: remove all hooks that whose id is <id>",
    ParameterDesc{ SwitchMap{}, ParameterDesc::Flags::None, 2, 2 },
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        get_hook_manager(parser[0], context).remove_hooks(parser[1]);
    }
};

EnvVarMap params_to_env_var_map(const ParametersParser& parser)
{
    std::unordered_map<String, String> vars;
    char param_name[] = "param0";
    for (size_t i = 0; i < parser.positional_count(); ++i)
    {
        param_name[sizeof(param_name) - 2] = '0' + i;
        vars[param_name] = parser[i];
    }
    return vars;
}

std::vector<String> params_to_shell(const ParametersParser& parser)
{
    std::vector<String> vars;
    for (size_t i = 0; i < parser.positional_count(); ++i)
        vars.push_back(parser[i]);
    return vars;
}

void define_command(const ParametersParser& parser, Context& context)
{
    auto begin = parser.begin();
    const String& cmd_name = *begin;

    if (CommandManager::instance().command_defined(cmd_name) and
        not parser.has_option("allow-override"))
        throw runtime_error("command '" + cmd_name + "' already defined");

    CommandFlags flags = CommandFlags::None;
    if (parser.has_option("hidden"))
        flags = CommandFlags::Hidden;

    String docstring;
    if (parser.has_option("docstring"))
        docstring = parser.option_value("docstring");

    String commands = parser[1];
    Command cmd;
    ParameterDesc desc;
    if (parser.has_option("env-params"))
    {
        desc = ParameterDesc{ SwitchMap{}, ParameterDesc::Flags::SwitchesAsPositional };
        cmd = [=](const ParametersParser& parser, Context& context) {
            CommandManager::instance().execute(commands, context, {},
                                               params_to_env_var_map(parser));
        };
    }
    if (parser.has_option("shell-params"))
    {
        desc = ParameterDesc{ SwitchMap{}, ParameterDesc::Flags::SwitchesAsPositional };
        cmd = [=](const ParametersParser& parser, Context& context) {
            CommandManager::instance().execute(commands, context, params_to_shell(parser));
        };
    }
    else
    {
        desc = ParameterDesc{ SwitchMap{}, ParameterDesc::Flags::SwitchesAsPositional, 0, 0 };
        cmd = [=](const ParametersParser& parser, Context& context) {
            CommandManager::instance().execute(commands, context);
        };
    }

    CommandCompleter completer;
    if (parser.has_option("file-completion"))
    {
        completer = [](const Context& context, CompletionFlags flags,
                       CommandParameters params,
                       size_t token_to_complete, ByteCount pos_in_token)
        {
             const String& prefix = params[token_to_complete];
             auto& ignored_files = context.options()["ignored_files"].get<Regex>();
             return Completions{ 0_byte, prefix.length(),
                                 complete_filename(prefix, ignored_files,
                                                   pos_in_token) };
        };
    }
    if (parser.has_option("client-completion"))
    {
        completer = [](const Context& context, CompletionFlags flags,
                       CommandParameters params,
                       size_t token_to_complete, ByteCount pos_in_token)
        {
             const String& prefix = params[token_to_complete];
             auto& cm = ClientManager::instance();
             return Completions{ 0_byte, prefix.length(),
                                 cm.complete_client_name(prefix, pos_in_token) };
        };
    }
    if (parser.has_option("buffer-completion"))
    {
        completer = [](const Context& context, CompletionFlags flags,
                       CommandParameters params,
                       size_t token_to_complete, ByteCount pos_in_token)
        {
             const String& prefix = params[token_to_complete];
             auto& bm = BufferManager::instance();
             return Completions{ 0_byte, prefix.length(),
                                 bm.complete_buffer_name(prefix, pos_in_token) };
        };
    }
    else if (parser.has_option("shell-completion"))
    {
        String shell_cmd = parser.option_value("shell-completion");
        completer = [=](const Context& context, CompletionFlags flags,
                        CommandParameters params,
                        size_t token_to_complete, ByteCount pos_in_token)
        {
            if (flags == CompletionFlags::Fast) // no shell on fast completion
                return Completions{};
            EnvVarMap vars = {
                { "token_to_complete", to_string(token_to_complete) },
                { "pos_in_token",      to_string(pos_in_token) }
            };
            String output = ShellManager::instance().eval(shell_cmd, context, params, vars);
            return Completions{ 0_byte, params[token_to_complete].length(), split(output, '\n') };
        };
    }
    if (parser.has_option("alias"))
        CommandManager::instance().register_commands(
            { cmd_name, parser.option_value("alias") },
            cmd, std::move(docstring), desc, flags, completer);
    else
        CommandManager::instance().register_command(
            cmd_name, cmd, std::move(docstring), desc, flags, completer);
}

const CommandDesc define_command_cmd = {
    "def",
    nullptr,
    "def <switches> <name> <commands>: define a command named <name> corresponding to <commands>",
    ParameterDesc{
        SwitchMap{ { "env-params", { false, "pass parameters as env variables param0..paramN" } },
                   { "shell-params", { false, "pass parameters to each shell escape as $0..$N" } },
                   { "allow-override", { false, "allow overriding existing command" } },
                   { "file-completion", { false, "complete parameters using filename completion" } },
                   { "client-completion", { false, "complete parameters using client name completion" } },
                   { "buffer-completion", { false, "complete parameters using buffer name completion" } },
                   { "shell-completion", { true, "complete the parameters using the given shell-script" } },
                   { "hidden", { false, "do not display the command as completion candidate" } },
                   { "alias", { true, "define an alias for this command" } },
                   { "docstring", { true, "set docstring for command" } } },
        ParameterDesc::Flags::None,
        2, 2
    },
    CommandFlags::None,
    CommandCompleter{},
    define_command
};

const CommandDesc echo_cmd = {
    "echo",
    nullptr,
    "echo <params>...: display given parameters in the status line",
    ParameterDesc{
        SwitchMap{ { "color", { true, "set message color" } },
                   { "debug", { false, "write to debug buffer instead of status line" } } },
        ParameterDesc::Flags::SwitchesOnlyAtStart
    },
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        String message;
        for (auto& param : parser)
            message += param + " ";
        if (parser.has_option("debug"))
            write_debug(message);
        else
        {
            auto color = get_color(parser.has_option("color") ?
                                   parser.option_value("color") : "StatusLine");
            context.print_status({ std::move(message), color } );
        }
    }
};


const CommandDesc debug_cmd = {
    "debug",
    nullptr,
    "debug <params>...: write debug informations in debug buffer",
    ParameterDesc{ SwitchMap{}, ParameterDesc::Flags::SwitchesOnlyAtStart, 1 },
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context&)
    {
        if (parser[0] == "info")
        {
            write_debug("pid: " + to_string(getpid()));
            write_debug("session: " + Server::instance().session());
        }
        else
            throw runtime_error("unknown debug command '" + parser[0] + "'");
    }
};

const CommandDesc source_cmd = {
    "source",
    nullptr,
    "source <filename>: execute commands contained in <filename>",
    single_name_param,
    CommandFlags::None,
    filename_completer,
    [](const ParametersParser& parser, Context& context)
    {
        String file_content = read_file(parse_filename(parser[0]));
        try
        {
            CommandManager::instance().execute(file_content, context);
        }
        catch (Kakoune::runtime_error& err)
        {
            write_debug("error while executing commands in file '" + parser[0]
                        + "'\n    " + err.what());
            throw;
        }
    }
};

OptionManager& get_options(const String& scope, const Context& context)
{
    if (prefix_match("global", scope))
        return GlobalOptions::instance();
    else if (prefix_match("buffer", scope))
        return context.buffer().options();
    else if (prefix_match("window", scope))
        return context.window().options();
    else if (prefix_match(scope, "buffer="))
        return BufferManager::instance().get_buffer(scope.substr(7_byte)).options();
    throw runtime_error("error: no such option container " + scope);
}

const CommandDesc set_option_cmd = {
    "set",
    nullptr,
    "set <switches> <scope> <name> <value>: set option <name> in <scope> to <value>",
    ParameterDesc{
        SwitchMap{ { "add", { false, "add to option rather than replacing it" } } },
        ParameterDesc::Flags::SwitchesOnlyAtStart,
        3, 3
    },
    CommandFlags::None,
    [](const Context& context, CompletionFlags,
       CommandParameters params, size_t token_to_complete,
       ByteCount pos_in_token) -> Completions
    {
        if (token_to_complete == 0)
            return { 0_byte, params[0].length(),
                     complete_scope(params[0].substr(0_byte, pos_in_token)) };
        else if (token_to_complete == 1)
        {
            OptionManager& options = get_options(params[0], context);
            return { 0_byte, params[1].length(),
                     options.complete_option_name(params[1], pos_in_token) };
        }
        else if (token_to_complete == 2 and
                 GlobalOptions::instance().option_exists(params[1]))
        {
            OptionManager& options = get_options(params[0], context);
            String val = options[params[1]].get_as_string();
            if (prefix_match(val, params[2]))
                return { 0_byte, params[2].length(), { std::move(val) } };
        }
        return Completions{};
    },
    [](const ParametersParser& parser, Context& context)
    {
        Option& opt = get_options(parser[0], context).get_local_option(parser[1]);
        if (parser.has_option("add"))
            opt.add_from_string(parser[2]);
        else
            opt.set_from_string(parser[2]);
    }
};

const CommandDesc declare_option_cmd = {
    "decl",
    nullptr,
    "decl <type> <name> [value]: declare option <name> of type <type>.\n"
    "set its initial value to <value> if given\n"
    "Available types:\n"
    "    int: integer\n"
    "    bool: boolean (true/false or yes/no)\n"
    "    str: character string\n"
    "    regex: regular expression\n"
    "    int-list: list of integers\n"
    "    str-list: list of character strings\n"
    "    line-flag-list: list of line flags\n",
    ParameterDesc{
        SwitchMap{ { "hidden", { false, "do not display option name when completing" } },
                   { "docstring", { true, "specify option description" } } },
        ParameterDesc::Flags::SwitchesOnlyAtStart,
        2, 3
    },
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        Option* opt = nullptr;

        OptionFlags flags = OptionFlags::None;
        if (parser.has_option("hidden"))
            flags = OptionFlags::Hidden;

        String docstring;
        if (parser.has_option("docstring"))
            docstring = parser.option_value("docstring");

        GlobalOptions& opts = GlobalOptions::instance();

        if (parser[0] == "int")
            opt = &opts.declare_option<int>(parser[1], docstring, 0, flags);
        else if (parser[0] == "bool")
            opt = &opts.declare_option<bool>(parser[1], docstring, 0, flags);
        else if (parser[0] == "str")
            opt = &opts.declare_option<String>(parser[1], docstring, "", flags);
        else if (parser[0] == "regex")
            opt = &opts.declare_option<Regex>(parser[1], docstring, Regex{}, flags);
        else if (parser[0] == "int-list")
            opt = &opts.declare_option<std::vector<int>>(parser[1], docstring, {}, flags);
        else if (parser[0] == "str-list")
            opt = &opts.declare_option<std::vector<String>>(parser[1], docstring, {}, flags);
        else if (parser[0] == "line-flag-list")
            opt = &opts.declare_option<std::vector<LineAndFlag>>(parser[1], docstring, {}, flags);
        else
            throw runtime_error("unknown type " + parser[0]);

        if (parser.positional_count() == 3)
            opt->set_from_string(parser[2]);
    }
};


KeymapManager& get_keymap_manager(const String& scope, Context& context)
{
    if (prefix_match("global", scope))
        return GlobalKeymaps::instance();
    else if (prefix_match("buffer", scope))
        return context.buffer().keymaps();
    else if (prefix_match("window", scope))
        return context.window().keymaps();
    throw runtime_error("error: no such keymap container " + scope);
}

KeymapMode parse_keymap_mode(const String& str)
{
    if (prefix_match("normal", str)) return KeymapMode::Normal;
    if (prefix_match("insert", str)) return KeymapMode::Insert;
    if (prefix_match("menu", str))   return KeymapMode::Menu;
    if (prefix_match("prompt", str)) return KeymapMode::Prompt;
    throw runtime_error("unknown keymap mode '" + str + "'");
}

CandidateList complete_mode(StringView prefix)
{
    CandidateList res;
    for (auto mode : { "normal", "insert", "menu", "prompt" })
    {
        if (prefix_match(mode, prefix))
            res.emplace_back(mode);
    }
    return res;
}

const CommandDesc map_key_cmd = {
    "map",
    nullptr,
    "map <scope> <mode> <key> <keys>: map <key> to <keys> in given mode at given scope.\n"
    "Valid scopes:\n"
    "    window\n"
    "    buffer\n"
    "    global\n"
    "Valid modes:\n"
    "    normal\n"
    "    insert\n"
    "    menu\n"
    "    prompt\n",
    ParameterDesc{ SwitchMap{}, ParameterDesc::Flags::None, 4, 4 },
    CommandFlags::None,
    [](const Context& context, CompletionFlags flags,
       CommandParameters params, size_t token_to_complete, ByteCount pos_in_token)
    {
        if (token_to_complete == 0)
            return Completions{ 0_byte, params[0].length(),
                                complete_scope(params[0].substr(0_byte, pos_in_token)) };
        if (token_to_complete == 1)
            return Completions{ 0_byte, params[0].length(),
                                complete_mode(params[1].substr(0_byte, pos_in_token)) };
        return Completions{};
    },
    [](const ParametersParser& parser, Context& context)
    {
        KeymapManager& keymaps = get_keymap_manager(parser[0], context);
        KeymapMode keymap_mode = parse_keymap_mode(parser[1]);

        KeyList key = parse_keys(parser[2]);
        if (key.size() != 1)
            throw runtime_error("only a single key can be mapped");

        KeyList mapping = parse_keys(parser[3]);
        keymaps.map_key(key[0], keymap_mode, std::move(mapping));
    }
};

const ParameterDesc context_wrap_params = {
    SwitchMap{ { "client", { true, "run in given client context" } },
               { "try-client", { true, "run in given client context if it exists, or else in the current one" } },
               { "buffer", { true, "run in a disposable context for each given buffer in the comma separated list argument" } },
               { "draft", { false, "run in a disposable context" } },
               { "no-hooks", { false, "disable hooks" } },
               { "itersel", { false, "run once for each selection with that selection as the only one" } } },
    ParameterDesc::Flags::SwitchesOnlyAtStart, 1
};

template<typename Func>
void context_wrap(const ParametersParser& parser, Context& context, Func func)
{
    const bool disable_hooks = parser.has_option("no-hooks");
    if (disable_hooks)
        GlobalHooks::instance().disable_hooks();
    auto restore_hooks = on_scope_end([&](){
        if (disable_hooks)
            GlobalHooks::instance().enable_hooks();
    });

    ClientManager& cm = ClientManager::instance();
    if (parser.has_option("buffer"))
    {
        auto names = split(parser.option_value("buffer"), ',');
        for (auto& name : names)
        {
            Buffer& buffer = BufferManager::instance().get_buffer(name);
            InputHandler input_handler{buffer, ( Selection{} )};
            func(parser, input_handler.context());
        }
        return;
    }

    Context* real_context = &context;
    if (parser.has_option("client"))
        real_context = &cm.get_client(parser.option_value("client")).context();
    else if (parser.has_option("try-client"))
    {
        Client* client = cm.get_client_ifp(parser.option_value("try-client"));
        if (client)
            real_context = &client->context();
    }

    if (parser.has_option("draft"))
    {
        InputHandler input_handler(real_context->buffer(), real_context->selections(), real_context->name());

        // We do not want this draft context to commit undo groups if the real one is
        // going to commit the whole thing later
        if (real_context->is_editing())
            input_handler.context().disable_undo_handling();

        if (parser.has_option("itersel"))
        {
            DynamicSelectionList sels{real_context->buffer(), real_context->selections()};
            ScopedEdition edition{input_handler.context()};
            for (auto& sel : sels)
            {
                input_handler.context().selections() = sel;
                func(parser, input_handler.context());
            }
        }
        else
            func(parser, input_handler.context());
    }
    else
    {
        if (parser.has_option("itersel"))
            throw runtime_error("-itersel makes no sense without -draft");
        func(parser, *real_context);
    }

    // force redraw of this client window
    if (real_context != &context and real_context->has_window())
        real_context->window().forget_timestamp();
}

const CommandDesc exec_string_cmd = {
    "exec",
    nullptr,
    "exec <switches> <keys>: execute given keys as if entered by user",
    context_wrap_params,
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        context_wrap(parser, context, [](const ParametersParser& parser, Context& context) {
            KeyList keys;
            for (auto& param : parser)
            {
                KeyList param_keys = parse_keys(param);
                keys.insert(keys.end(), param_keys.begin(), param_keys.end());
            }
            exec_keys(keys, context);
        });
    }
};

const CommandDesc eval_string_cmd = {
    "eval",
    nullptr,
    "eval <switches> <keys>: execute commands as if entered by user",
    context_wrap_params,
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        context_wrap(parser, context, [](const ParametersParser& parser, Context& context) {
            String command;
            for (auto& param : parser)
                command += param + " ";
            CommandManager::instance().execute(command, context);
        });
    }
};

const CommandDesc prompt_cmd = {
    "prompt",
    nullptr,
    "prompt <prompt> <register> <command>: prompt the use to enter a text string "
    "stores it in <register> and then executes <command>",
    ParameterDesc{
        SwitchMap{ { "init", { true, "set initial prompt content" } } },
        ParameterDesc::Flags::None, 3, 3
    },
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& params, Context& context)
    {
        if (params[1].length() != 1)
            throw runtime_error("register name should be a single character");
        const char reg = params[1][0];
        const String& command = params[2];

        String initstr;
        if (params.has_option("init"))
            initstr = params.option_value("init");

        context.input_handler().prompt(
            params[0], std::move(initstr), get_color("Prompt"), Completer{},
            [=](const String& str, PromptEvent event, Context& context)
            {
                if (event != PromptEvent::Validate)
                    return;
                RegisterManager::instance()[reg] = memoryview<String>(str);

                CommandManager::instance().execute(command, context);
            });
    }
};

const CommandDesc menu_cmd = {
    "menu",
    nullptr,
    "menu <switches> <name1> <commands1> <name2> <commands2>...: display a menu and execute commands for the selected item",
    ParameterDesc{
        SwitchMap{ { "auto-single", { false, "instantly validate if only one item is available" } },
                   { "select-cmds", { false, "each item specify an additional command to run when selected" } } }
    },
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        const bool with_select_cmds = parser.has_option("select-cmds");
        const size_t modulo = with_select_cmds ? 3 : 2;

        const size_t count = parser.positional_count();
        if (count == 0 or (count % modulo) != 0)
            throw wrong_argument_count();

        if (count == modulo and parser.has_option("auto-single"))
        {
            CommandManager::instance().execute(parser[1], context);
            return;
        }

        std::vector<String> choices;
        std::vector<String> commands;
        std::vector<String> select_cmds;
        for (int i = 0; i < count; i += modulo)
        {
            choices.push_back(parser[i]);
            commands.push_back(parser[i+1]);
            if (with_select_cmds)
                select_cmds.push_back(parser[i+2]);
        }

        context.input_handler().menu(choices,
            [=](int choice, MenuEvent event, Context& context) {
                if (event == MenuEvent::Validate and choice >= 0 and choice < commands.size())
                  CommandManager::instance().execute(commands[choice], context);
                if (event == MenuEvent::Select and choice >= 0 and choice < select_cmds.size())
                  CommandManager::instance().execute(select_cmds[choice], context);
            });
    }
};

const CommandDesc info_cmd = {
    "info",
    nullptr,
    "info <switches> <params>...: display an info box with the params as content",
    ParameterDesc{
        SwitchMap{ { "anchor", { true, "set info anchoring (left, right, or cursor)" } },
                   { "title", { true, "set info title" } } },
        ParameterDesc::Flags::None, 0, 1
    },
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        context.ui().info_hide();
        if (parser.positional_count() > 0)
        {
            MenuStyle style = MenuStyle::Prompt;
            DisplayCoord pos = context.ui().dimensions();
            pos.column -= 1;
            if (parser.has_option("anchor"))
            {
                style =  MenuStyle::Inline;
                const auto& sel = context.selections().main();
                auto it = sel.cursor();
                String anchor = parser.option_value("anchor");
                if (anchor == "left")
                    it = sel.min();
                else if (anchor == "right")
                    it = sel.max();
                else if (anchor != "cursor")
                    throw runtime_error("anchor param must be one of [left, right, cursor]");
                pos = context.window().display_position(it);
            }
            const String& title = parser.has_option("title") ? parser.option_value("title") : "";
            context.ui().info_show(title, parser[0], pos, get_color("Information"), style);
        }
    }
};

const CommandDesc try_catch_cmd = {
    "try",
    nullptr,
    "try <command> [catch <error_command>]: execute command in current context.\n"
    "if an error is raised and <error_command> is specified, execute it.\n"
    "The error is not propagated further.",
    ParameterDesc{ SwitchMap{}, ParameterDesc::Flags::None, 1, 3 },
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        if (parser.positional_count() == 2)
            throw wrong_argument_count();

        const bool do_catch = parser.positional_count() == 3;
        if (do_catch and parser[1] != "catch")
            throw runtime_error("usage: try <commands> [catch <on error commands>]");

        CommandManager& command_manager = CommandManager::instance();
        try
        {
            command_manager.execute(parser[0], context);
        }
        catch (Kakoune::runtime_error& e)
        {
            if (do_catch)
                command_manager.execute(parser[2], context);
        }
    }
};

static Completions complete_colalias(const Context&, CompletionFlags flags,
                                     const String& prefix, ByteCount cursor_pos)
{
    return {0_byte, prefix.length(),
            ColorRegistry::instance().complete_alias_name(prefix, cursor_pos)};
}

const CommandDesc define_color_alias_cmd = {
    "colalias",
    "ca",
    "colalias <name> <color>: set <name> to refer to color <color> (which can be an alias itself)",
    ParameterDesc{ SwitchMap{}, ParameterDesc::Flags::None, 2, 2 },
    CommandFlags::None,
    PerArgumentCommandCompleter({ complete_colalias, complete_colalias }),
    [](const ParametersParser& parser, Context& context)
    {
        ColorRegistry::instance().register_alias(parser[0], parser[1], true);
    }
};

const CommandDesc set_client_name_cmd = {
    "nameclient",
    "nc",
    "nameclient <name>: set current client name to <name>",
    single_name_param,
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        if (ClientManager::instance().validate_client_name(parser[0]))
            context.set_name(parser[0]);
        else if (context.name() != parser[0])
            throw runtime_error("client name '" + parser[0] + "' is not unique");
    }
};

const CommandDesc set_register_cmd = {
    "reg",
    nullptr,
    "reg <name> <value>: set register <name> to <value>",
    ParameterDesc{ SwitchMap{}, ParameterDesc::Flags::None, 2, 2 },
    CommandFlags::None,
    CommandCompleter{},
    [](const ParametersParser& parser, Context& context)
    {
        if (parser[0].length() != 1)
            throw runtime_error("register names are single character");
        RegisterManager::instance()[parser[0][0]] = memoryview<String>(parser[1]);
    }
};

const CommandDesc change_working_directory_cmd = {
    "cd",
    nullptr,
    "cd <dir>: change server working directory to <dir>",
    single_name_param,
    CommandFlags::None,
    filename_completer,
    [](const ParametersParser& parser, Context&)
    {
        if (chdir(parse_filename(parser[0]).c_str()) != 0)
            throw runtime_error("cannot change to directory " + parser[0]);
    }
};

class RegisterRestorer
{
public:
    RegisterRestorer(char name, const Context& context)
      : m_name(name)
    {
        memoryview<String> save = RegisterManager::instance()[name].values(context);
        m_save = std::vector<String>(save.begin(), save.end());
    }

    ~RegisterRestorer()
    { RegisterManager::instance()[m_name] = m_save; }

private:
    std::vector<String> m_save;
    char                m_name;
};

}

void exec_keys(const KeyList& keys, Context& context)
{
    RegisterRestorer quote('"', context);
    RegisterRestorer slash('/', context);

    ScopedEdition edition(context);

    for (auto& key : keys)
        context.input_handler().handle_key(key);
}

static void register_command(CommandManager& cm, const CommandDesc& c)
{
    if (c.alias)
        cm.register_commands({ c.name, c.alias }, c.func, c.docstring, c.params, c.flags, c.completer);
    else
        cm.register_command(c.name, c.func, c.docstring, c.params, c.flags, c.completer);
}

void register_commands()
{
    CommandManager& cm = CommandManager::instance();

    cm.register_command("nop", [](const ParametersParser&, Context&){}, "do nothing", {});

    register_command(cm, edit_cmd);
    register_command(cm, force_edit_cmd);
    register_command(cm, write_cmd);
    register_command(cm, writeall_cmd);
    register_command(cm, quit_cmd);
    register_command(cm, force_quit_cmd);
    register_command(cm, write_quit_cmd);
    register_command(cm, force_write_quit_cmd);
    register_command(cm, buffer_cmd);
    register_command(cm, delbuf_cmd);
    register_command(cm, force_delbuf_cmd);
    register_command(cm, namebuf_cmd);
    register_command(cm, define_highlighter_cmd);
    register_command(cm, add_highlighter_cmd);
    register_command(cm, rm_highlighter_cmd);
    register_command(cm, add_hook_cmd);
    register_command(cm, rm_hook_cmd);
    register_command(cm, define_command_cmd);
    register_command(cm, echo_cmd);
    register_command(cm, debug_cmd);
    register_command(cm, source_cmd);
    register_command(cm, set_option_cmd);
    register_command(cm, declare_option_cmd);
    register_command(cm, map_key_cmd);
    register_command(cm, exec_string_cmd);
    register_command(cm, eval_string_cmd);
    register_command(cm, prompt_cmd);
    register_command(cm, menu_cmd);
    register_command(cm, info_cmd);
    register_command(cm, try_catch_cmd);
    register_command(cm, define_color_alias_cmd);
    register_command(cm, set_client_name_cmd);
    register_command(cm, set_register_cmd);
    register_command(cm, change_working_directory_cmd);
}
}