#pragma once

#include <u.h>
#include <libn.h>

#include <termios.h>
#include <unibilium.h>

#define iota(x)             1 << (x)

typedef struct RGB8   RGB8;
typedef struct Pen    Pen;

typedef struct Dot    Dot;
typedef struct Cell   Cell;
typedef struct Row    Row;
typedef struct Buffer Buffer;
typedef struct Window Window;

typedef struct Node   Node;
typedef struct Key    Key;
typedef struct Input  Input;

typedef struct Term   Term;

struct RGB8
{
    uint8 r, g, b;
};

enum
{
    PenNormal    = 0,
    PenBold      = iota(0),
    PenDim       = iota(1),
    PenInvis     = iota(2),
    PenItalic    = iota(3),
    PenReverse   = iota(4),
    PenStrike    = iota(5),
    PenUnderline = iota(6),
    PenBlink     = iota(7),
    /* ... */
    PenRGB       = iota(15),
};

struct Pen
{
    ushort state;
    union {
        /* 256 color (legacy) */
        struct {
            sshort fg : 8, bg : 8; /* 0 - 255 or COLOUR_DEFAULT */
        } col;
        /* true color (modern) */
        struct {
            RGB8 fg, bg;
        } rgb;
    };
};

/* outputs */
struct Cell 
{
    rune txt;
    Pen  pen;
}; 

struct Row 
{
	Cell *cells;
	uint  dirty : 1;
};

struct Dot
{
    int row, col;
};

/*
 * scroll.top & scroll.bot are pointers into the viewport.
 *
 *                                     scroll back buffer
 *
 *                      scroll.buf->+----------------+-----+
 *                                  |                |     | ^  \
 *                                  |     before     |     | |  |
 *    current terminal content      |    viewport    |     | |  |
 *                                  |                |     |    |
 *    +----------------+-----+\     |                |     | s   > scroll.above
 *  ^ |                |  i  | \    |                |  i  | c  |
 *  | |                |  n  |  \   |                |  n  | r  |
 *    |                |  v  |   \  |                |  v  | o  |
 *    |                |  i  |    \ |                |  i  | l  /
 *    |    buffer      |  s  |     >|<- scroll.index |  s  | l  \
 *  h |                |  i  |    / |                |  i  |    |
 *    |                |  b  |   /  |     after      |  b  | s   > scroll.below
 *    |                |  l  |  /   |    viewport    |  l  | i  |
 *  v |                |  e  | /    |                |  e  | z  /
 *    +----------------+-----+/     |     unused     |     | e
 *     <-    maxw         ->        |   scroll back  |     |
 *     <-    w       ->             |     buffer     |     | |
 *                                  |                |     | |
 *                                  |                |     | v
 *        scroll.buf + scroll.size->+----------------+-----+
 *                                   <-    maxw           ->
 *                                   <-    w       ->
 */

struct Buffer 
{
	int   w, h;        /* dimension of buffer */
    Pen   pen;         /* default attributes */
	int   maxw;        /* allocated cells (maximal cols over time) */
	Row  *row;         /* array of row pointers of size 'h' */
    struct {
        Row *buf;
        Row *top;
        Row *bot;
        int size;
        int index;
        int above;
        int below;
    } scroll;
    Dot  cur, save;    /* cursor position within buffer */
};

struct Window
{
    struct Buffer;
    int     top,  left;
    uchar   curvis : 1;
    uchar   blink  : 2;

    Window *parent, *child, *link;
};

/* input */
struct Key 
{
    int   type;
    int   mods;
    uchar utf8[UTFmax+1];
    union {
        rune pt;
        int  num;
        int  sym;
        char mouse[4];
    } code;
};

struct KeyInfo
{
    int type;
    int sym;
    int modmask;
    int modset;
};

struct Input
{
    int fd;
    int flags;
    int wait; /* in ms */

    /* modifiers */
    uchar closed  : 1;
    uchar started : 1;
    uchar hasold  : 1;

    struct termios oldterm;

    /* buffer */
    struct {
        long off;
        uchar *b, *c, *e, bytes[256];
    } rbuf;
    struct {
        uchar *s, bytes[256];
    } ebuf;

    /* key data */
    Node  *keys;
    struct KeyInfo c0[32];
};


struct Term
{
    /* meta data */
    char       *name;
    unibi_term *info;
    struct {
        uchar  altscreen : 1;
        uchar  cursorvis : 1;
        uchar  mouse     : 1;
    } mode;
    struct {
        uchar bce : 1;
        int   colors;
    } cap;

    /* input capture */
    Input input;

    /* output display */
    Window *root;
    Pen     pen;

    /* raw text to pty */
    int fd;
    struct {
        char *c, b[512];
    } buf;

    struct {
        int len;
        char *b;
    } tmp;

    /* info */
    struct {
        /* Positioning */
        char *cup;  // cursor_address
        char *vpa;  // row_address   == vertical position absolute
        char *hpa;  // column_address = horizontal position absolute

        /* Moving */
        char *cuu; char *cuu1; // Cursor Up
        char *cud; char *cud1; // Cursor Down
        char *cuf; char *cuf1; // Cursor Forward == Right
        char *cub; char *cub1; // Cursor Backward == Left

        /* Editing */
        char *ich; char *ich1; // Insert Character
        char *dch; char *dch1; // Delete Character
        char *il;  char *il1;  // Insert Line
        char *dl;  char *dl1;  // Delete Line
        char *ech;             // Erase Character
        char *ed2;             // Erase Data 2 == Clear screen
        char *stbm;            // Set Top/Bottom Margins

        /* formatting */
        char *sgr;              // Select Graphic Rendition
        char *sgr0;             // Exit Attribute Mode
        char *sgr_i0, *sgr_i1;  // SGR italic off/on
        char *sgr_fg;           // SGR foreground colour
        char *sgr_bg;           // SGR background colour

        /* Mode setting/clearing */
        char *sm_csr; char *rm_csr; // Set/reset mode: Cursor visible

        /* augmentations to terminfo */
        struct {
            char *rgbf;  // rgb foreground
            char *rgbb;  // rgb background
            char *smxx;  // strikethrough
            char *smulx; // curly underline
        } ext;
    } esc;

    Term *link;
};

/* functions */
void    tresize(Term *t);

Window *wmake(Window *root, int top, int left, int w, int h, int scroll);
void    wresize(Window *root, int w, int h);
void    wputrune(Window *win, rune r);
void    wscroll(Window *win, int s);