#ifndef LLSH_INPUT_H
#define LLSH_INPUT_H

#include "util.h"
#include <pthread.h>
#include <stdbool.h>
#include <stddef.h>

/* ------------------------------------------------------------------ */
/* Keys (decoded)                                                      */
/* ------------------------------------------------------------------ */

typedef struct {
    int kind;
    unsigned int cp; /* KEY_CHAR: codepoint */
} input_key;

enum {
    KEY_CHAR,
    KEY_BACKSPACE,
    KEY_DELETE,
    KEY_LEFT,
    KEY_RIGHT,
    KEY_UP,
    KEY_DOWN,
    KEY_HOME,
    KEY_END,
    KEY_PAGEUP,
    KEY_PAGEDOWN,
    KEY_ENTER,
    KEY_NEWLINE,
    KEY_TAB,
    KEY_BACKTAB,
    KEY_ESC,
    KEY_CTRL_A,
    KEY_CTRL_C,
    KEY_CTRL_D,
    KEY_CTRL_E,
    KEY_CTRL_K,
    KEY_CTRL_L,
    KEY_CTRL_U,
    KEY_CTRL_W,
    KEY_CTRL_Y,
    KEY_UNDO,
    KEY_UNKNOWN,
};

/* ------------------------------------------------------------------ */
/* Actions                                                             */
/* ------------------------------------------------------------------ */

typedef struct {
    int kind;
    char *text; /* ACT_SUBMIT: owned buffer */
} input_action;

enum {
    ACT_NONE,
    ACT_SUBMIT,
    ACT_QUIT,
    ACT_STOP,
    ACT_TOGGLE_MODE,
    ACT_CLEAR_SCREEN,
    /* Enter on a trailing backslash: line continuation (newline inserted). */
    ACT_NEWLINE,
};

void input_action_free(input_action *a);

/* ------------------------------------------------------------------ */
/* Event list (owned)                                                  */
/* ------------------------------------------------------------------ */

/* True circular FIFO: pushes/pops advance indices modulo `cap` and never
 * shift live elements. */
typedef struct {
    input_key *items;
    unsigned char **raws;
    size_t *lens;
    size_t len;
    size_t head;
    size_t cap;
} evlist;

void evlist_init(evlist *l);
void evlist_free(evlist *l);
void evlist_push(evlist *l, input_key k, const unsigned char *raw, size_t raw_len);
/* Remove the oldest event (frees its raw buffer). No-op when empty. */
void evlist_pop(evlist *l);

/* ------------------------------------------------------------------ */
/* Parser                                                              */
/* ------------------------------------------------------------------ */

typedef struct {
    int state; /* KST_* */
    xbuf seq;  /* raw sequence bytes (ESC + rest) */
    xbuf csi_params;
    unsigned char utf8[8];
    size_t utf8_len;
    bool pasting; /* bracketed paste mode (CSI 200/201) */
} key_parser;

enum { KST_GROUND, KST_ESCAPE, KST_CSI, KST_SS3 };

void key_parser_init(key_parser *p);
void key_parser_free(key_parser *p);
/* Feed a chunk of terminal bytes; emits events into `out`. */
size_t key_parser_feed(key_parser *p, const unsigned char *in, size_t n, evlist *out);
/* Drain any partial sequence; emits at most one event. Returns 1 if emitted. */
int key_parser_flush(key_parser *p, evlist *out);

/* ------------------------------------------------------------------ */
/* Editor (multi-line)                                                 */
/* ------------------------------------------------------------------ */

typedef struct {
    char *text;
    size_t caret;
} editor_undo_entry;

typedef struct {
    char *text;  /* owned; lines separated by '\n' */
    size_t caret; /* byte offset, always on a UTF-8 boundary */
    char *killed; /* most recent kill/delete, for Ctrl+Y yank */
    editor_undo_entry *undo; /* bounded undo stack (oldest -> newest) */
    size_t undo_len;
    size_t undo_cap;
} editor;

void editor_init(editor *e);
void editor_free(editor *e);
void editor_clear(editor *e);
void editor_set(editor *e, const char *text);
char *editor_text(const editor *e);
bool editor_is_empty(const editor *e);
/* Number of lines in the buffer (1 when empty). */
size_t editor_line_count(const editor *e);
/* 0-based index of the line holding the caret. */
size_t editor_caret_line(const editor *e);
void editor_apply(editor *e, input_key key, input_action *a);

/* Terminal-wrap geometry for the multi-line input. These let the renderer and
 * the tests agree on how a buffer of a given width breaks into physical rows
 * and where the caret lands, without touching a tty. The model matches the
 * delayed-wrap auto-wrapping used by xterm/VTE. */
void input_wrap_caret(const char *text, size_t caret, size_t w,
                      size_t *row, size_t *col);
size_t input_wrap_total(const char *text, size_t w);
/* True when the caret sits in the delayed-wrap pending state: on the last
 * column of a row immediately after printing that row's final character. */
bool input_wrap_pending(const char *text, size_t caret, size_t w);

/* ------------------------------------------------------------------ */
/* History                                                             */
/* ------------------------------------------------------------------ */

#define LLSH_HISTORY_LIMIT 100

/* `entries` is oldest -> newest with a ring head: live entries are
 * items[head .. len), and `index` is an absolute position in items. */
typedef struct {
    strlist entries;
    size_t head;
    bool active;
    size_t index;
    char *snapshot;
    char *path;
} input_history;

input_history *input_history_new(void);
/* Open history at path; loads existing entries. NULL on error. */
input_history *input_history_open(const char *path);
void input_history_free(input_history *h);
void input_history_push(input_history *h, const char *text);
void input_history_reset(input_history *h);

/* Consolidated Up/Down history policy. dir: -1 for Up, +1 for Down.
 * caret_line describes the editor so the policy can tell a caret move
 * (mid-buffer) from a history recall (from the relevant edge, or mid-walk).
 * Returns an owned entry to load (caller frees), or NULL when the press
 * should move the caret instead / the walk is exhausted. */
char *input_history_walk(input_history *h, int dir, size_t caret_line,
                         const char *current);
bool input_history_persist(input_history *h);

/* ------------------------------------------------------------------ */
/* Terminal / reader                                                   */
/* ------------------------------------------------------------------ */

/* Enable raw mode + bracketed paste + kitty keyboard protocol. */
int input_setup_terminal(void);
/* Restore terminal; write teardown sequences. */
void input_teardown_terminal(void);

typedef struct input_key_reader input_key_reader;

typedef struct {
    key_parser *parser;
    /* Optional direct hook, called for every event in the reader thread. */
    int (*send)(input_key_reader *r, const input_key *k, const unsigned char *raw,
                size_t raw_len);
} reader_ctx;

input_key_reader *input_key_reader_new(reader_ctx *ctx);
int input_key_reader_start(input_key_reader *r);
/* Push an event into the reader's queue (used by tests). */
void input_key_reader_send(input_key_reader *r, const input_key *k);
/* Push an event with a raw payload into the reader's queue (used by tests). */
void input_key_reader_send_raw(input_key_reader *r, const input_key *k,
                               const char *raw);
/* Pop a queued event (non-blocking); false when the queue is empty.
 * When `raw` is non-NULL the caller receives an owned copy of the event's
 * raw bytes (the queue frees its own slot on pop); release it with
 * input_raw_free once consumed. Pass NULL for `raw`/`raw_len` when only the
 * decoded key is needed. */
bool input_key_reader_recv(input_key_reader *r, input_key *out,
                           const unsigned char **raw, size_t *raw_len);
/* Release a raw buffer returned by input_key_reader_recv. NULL-safe. */
void input_raw_free(const unsigned char *raw);
void input_key_reader_stop(input_key_reader *r);
void input_key_reader_free(input_key_reader *r);

/* True when stdin is a terminal (used to gate DSR queries). */
int input_isatty(void);

/* ------------------------------------------------------------------ */
/* Shell shadow                                                        */
/* ------------------------------------------------------------------ */

/* Feed one key into the shell-mode shadow editor. If the key finished a
 * non-empty command, the shadow is cleared and the submitted text is
 * returned (caller frees); otherwise NULL. */
char *shell_shadow_apply(editor *shadow, input_key key);

/* History file location: `config_dir/llsh/history`. */
char *input_history_path_for(const char *config_dir);
/* $XDG_CONFIG_HOME when set to an absolute path, else $HOME/.config,
 * else /tmp. */
char *input_default_config_dir(void);
/* default_history_path = history_path_for(default_config_dir). */
char *input_default_history_path(void);

/* ------------------------------------------------------------------ */
/* Display                                                             */
/* ------------------------------------------------------------------ */

/* Display width in terminal columns (ANSI escapes skipped). */
size_t input_display_len(const char *s);
/* Display width of the first n bytes of s. */
size_t input_display_len_n(const char *s, size_t n);

#endif