menu.c

#include "menu.h"

/* This supports only a single menu instance to reduce programming clutter.  
   It is designed for simple LCD displays.  */


#ifndef min
#define min(a,b) ((a) < (b) ? (a) : (b))
#endif

//#define MENU_WRAP


typedef struct
{
    menu_t *current;
    uint8_t rows;
    uint8_t preview;
    menu_style_t style;
    void (*display)(const char *title, int row, 
                    const char *item_name, bool highlight);
} menu_data_t;

static menu_data_t menu_data;


void 
menu_show (void)
{
    /* Probably need a callback here.  */
    int i;
    menu_t *menu = menu_data.current;

    for (i = 0; i < menu_data.rows; i++)
    {
        uint8_t item;

        // item = (top + i) % menu->size;
        item = menu->top + i;
        if (item >= menu->size)
            break;

        menu_data.display (menu->title, i, menu->items[item].name,
                           item == menu->index);
    }
}


void
menu_top_best (menu_t *menu)
{
    if (menu->index <= menu_data.preview)
        menu->top = 0;
    else
        menu->top = menu->index - menu_data.preview;
}


/* Display a new menu, saving previous menu to return to later.  */
bool
menu_display (menu_t *menu)
{
    menu->parent = menu_data.current;
    menu_data.current = menu;
    menu_top_best (menu_data.current);
    menu_show ();
    return 0;
}


/* Display a new menu with prompt at top.  */
bool
menu_display_top (menu_t *menu)
{
    menu->parent = menu_data.current;
    menu_data.current = menu;
    menu_data.current->index = 0;
    menu_top_best (menu_data.current);
    menu_show ();
    return 0;
}


/* Quit the current menu and return to parent menu.  */
void 
menu_quit (void)
{
    /* Can't exit main menu.  */
    if (!menu_data.current->parent)
    {
        /* Redraw.  */
        menu_show ();
        return;
    }

    menu_data.current = menu_data.current->parent;
    menu_show ();
}


/* Go to an item in a menu.  */
void 
menu_goto (int index)
{
    if (index > menu_data.current->size)
        index = menu_data.current->size - 1;
    else if (index < 0)
        index = 0;

    menu_data.current->index = index;
    menu_top_best (menu_data.current);
    menu_show ();
}


/* Set menu index and call action if appropriate.  */
void
menu_index_set (menu_t *menu, uint8_t index)
{
    menu_t *save;

    /* Handle bogus values.  */
    if (index >= menu->size)
        index = 0;

    /* Need to set current menu so action can find out which menu
       is active.  */
    save = menu_data.current;
    menu_data.current = menu;
    menu->index = index;
    menu_top_best (menu);

    if (menu->items[menu->index].action)
        menu->items[menu->index].action ();

    menu_data.current = save;
}


/* Perform action for current menu item.  */
void 
menu_select (void)
{
    if (!menu_data.current->items[menu_data.current->index].action
        || menu_data.current->items[menu_data.current->index].action ())
        menu_quit ();
}


/* Go to next menu item.  */
void 
menu_next (void)
{
    if (menu_data.current->index >= menu_data.current->size - 1)
    {
        /* Reached bottom of menu.  */
#ifdef MENU_WRAP
        /* Wrap back to top of menu.  */
        menu_data.current->index = 0;
#endif
    }
    else
    {
        int spare = menu_data.current->size 
            - (menu_data.current->top + menu_data.rows);

        menu_data.current->index++;
        if (menu_data.current->index >= menu_data.rows 
            + menu_data.current->top - menu_data.preview
            && spare > 0)
            menu_data.current->top++;
    }

    menu_show ();
}


/* Go to previous menu item.  */
void 
menu_prev (void)
{
    if (menu_data.current->index == 0)
    {
        /* Reached top of menu.  */
#ifdef MENU_WRAP
        /* Wrap back to bottom of menu.  */
        menu_data.current->index = menu_data.current->size - 1;
#endif
    }
    else
    {
        int spare = menu_data.current->top; 

        menu_data.current->index--;
        if (spare > 0 && menu_data.current->index - menu_data.current->top
            < menu_data.preview)
            menu_data.current->top--;
    }

    menu_show ();
}


void menu_style_set (menu_style_t style)
{
    menu_data.style = style;
}


menu_t *
menu_current_get (void)
{
    return menu_data.current;
}


uint8_t
menu_current_index_get (void)
{
    menu_t *menu;

    menu = menu_current_get();
    return menu->index;
}


void 
menu_init (int rows,
           void (*display)(const char *title, int row,
                           const char *item_name, bool highlight))
{
    menu_data.rows = rows;
    /* Preview controls how many menu rows are displayed before the
       prompt at the top of the screen or after the prompt at the
       bottom of the screen.   */
    if (rows > 2)
        menu_data.preview = 1;
    else
        menu_data.preview = 0;
    menu_data.style = MENU_STYLE_SCROLL;
    menu_data.display = display;
}