// Header file for the low level input library.
#ifndef INPUT_COMMON_H
#define INPUT_COMMON_H

#include <stddef.h>

#include <functional>

#include "common.h"
#include "maybe.h"

enum class readline_cmd_t {
    beginning_of_line,
    end_of_line,
    forward_char,
    backward_char,
    forward_word,
    backward_word,
    forward_bigword,
    backward_bigword,
    history_search_backward,
    history_search_forward,
    delete_char,
    backward_delete_char,
    kill_line,
    yank,
    yank_POP,
    complete,
    complete_AND_SEARCH,
    pager_toggle_search,
    beginning_of_history,
    end_of_history,
    backward_kill_line,
    kill_whole_line,
    kill_word,
    kill_bigword,
    backward_kill_word,
    backward_kill_path_component,
    backward_kill_bigword,
    history_token_search_backward,
    history_token_search_forward,
    self_insert,
    transpose_chars,
    transpose_words,
    upcase_word,
    downcase_word,
    capitalize_word,
    vi_arg_digit,
    vi_delete_to,
    execute,
    beginning_of_buffer,
    end_of_buffer,
    repaint,
    force_repaint,
    up_line,
    down_line,
    suppress_autosuggestion,
    accept_autosuggestion,
    begin_selection,
    swap_selection_start_stop,
    end_selection,
    kill_selection,
    forward_jump,
    backward_jump,
    forward_jump_till,
    backward_jump_till,
    func_and,
    expand_abbr,
    cancel,
    repeat_jump,
    reverse_repeat_jump,
};

// The range of key codes for inputrc-style keyboard functions.
enum {
    R_BEGIN_INPUT_FUNCTIONS = static_cast<int>(readline_cmd_t::beginning_of_line),
    R_END_INPUT_FUNCTIONS = static_cast<int>(readline_cmd_t::reverse_repeat_jump) + 1
};

/// Represents an event on the character input stream.
enum class char_event_type_t : uint8_t {
    /// A character was entered.
    charc,

    /// A readline event.
    readline,

    /// A timeout was hit.
    timeout,

    /// end-of-file was reached.
    eof,

    /// An event was handled internally, or an interrupt was received. Check to see if the reader
    /// loop should exit.
    check_exit,
};

class char_event_t {
    union {
        /// Set if the type is charc.
        wchar_t c;

        /// Set if the type is readline.
        readline_cmd_t rl;
    } v_{};

   public:
    char_event_type_t type;

    bool is_timeout() const { return type == char_event_type_t::timeout; }

    bool is_char() const { return type == char_event_type_t::charc; }

    bool is_eof() const { return type == char_event_type_t::eof; }

    bool is_check_exit() const { return type == char_event_type_t::check_exit; }

    bool is_readline() const { return type == char_event_type_t::readline; }

    wchar_t get_char() const {
        assert(type == char_event_type_t::charc && "Not a char type");
        return v_.c;
    }

    readline_cmd_t get_readline() const {
        assert(type == char_event_type_t::readline && "Not a readline type");
        return v_.rl;
    }

    /* implicit */ char_event_t(wchar_t c) : type(char_event_type_t::charc) { v_.c = c; }

    /* implicit */ char_event_t(readline_cmd_t rl) : type(char_event_type_t::readline) {
        v_.rl = rl;
    }

    /* implicit */ char_event_t(char_event_type_t type) : type(type) {
        assert(type != char_event_type_t::charc && type != char_event_type_t::readline &&
               "Cannot create a char event with this constructor");
    }
};

/// A type of function invoked on interrupt.
/// \return the event which is to be returned to the reader loop, or none if VINTR is 0.
using interrupt_func_t = maybe_t<char_event_t> (*)();

/// Init the library with an interrupt function.
void input_common_init(interrupt_func_t func);

/// Adjust the escape timeout.
class environment_t;
void update_wait_on_escape_ms(const environment_t &vars);

/// Function used by input_readch to read bytes from stdin until enough bytes have been read to
/// convert them to a wchar_t. Conversion is done using mbrtowc. If a character has previously been
/// read and then 'unread' using \c input_common_unreadch, that character is returned.
/// This function never returns a timeout.
char_event_t input_common_readch();

/// Like input_common_readch(), except it will wait at most WAIT_ON_ESCAPE milliseconds for a
/// character to be available for reading.
/// If \p dequeue_timeouts is set, remove any timeout from the queue; otherwise retain them.
char_event_t input_common_readch_timed(bool dequeue_timeouts = false);

/// Enqueue a character or a readline function to the queue of unread characters that input_readch
/// will return before actually reading from fd 0.
void input_common_queue_ch(char_event_t ch);

/// Add a character or a readline function to the front of the queue of unread characters.  This
/// will be the first character returned by input_readch (unless this function is called more than
/// once).
void input_common_next_ch(char_event_t ch);

/// Adds a callback to be invoked at the next turn of the "event loop." The callback function will
/// be invoked and passed arg.
void input_common_add_callback(std::function<void(void)>);

#endif