Add ability to adjust RTC (#107)

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## Description
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This PR adds the ability to set the time from the menu.
The underlying logic is sound given what is currently available within
libdragon, but expected changes are noted (like `settimeofday`) for
future improvement and will need to be revisited once available.
A future PR will need to add better GUI components for numeric control.

## Motivation and Context
<!--- What does this sample do? What problem does it solve? -->
<!--- If it fixes/closes/resolves an open issue, please link to the
issue here -->
#106

## How Has This Been Tested?
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to -->
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locally on a SC64

## Screenshots
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## Types of changes
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the boxes that apply: -->
- [x] Improvement (non-breaking change that adds a new feature)
- [ ] Bug fix (fixes an issue)
- [ ] Breaking change (breaking change)
- [ ] Config and build (change in the configuration and build system,
has no impact on code or features)

## Checklist:
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- [ ] My code follows the code style of this project.
- [ ] My change requires a change to the documentation.
- [ ] I have updated the documentation accordingly.
- [ ] I have added tests to cover my changes.
- [ ] All new and existing tests passed.

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Signed-off-by: GITHUB_USER <GITHUB_USER_EMAIL>

src/menu/views/rtc.c

@@ -1,26 +1,165 @@
-#include <time.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <libdragon.h>
+#include <sys/time.h>
 #include "../sound.h"
 #include "views.h"
 
-// FIXME: add implementation!
-// struct {
-//     uint16_t seconds;
-//     uint16_t minutes;
-//     uint16_t hours;
-//     uint16_t day;
-//     uint16_t month;
-//     uint16_t year;
-// } adjusted_datetime;
+#define MAX(a,b)  ({ typeof(a) _a = a; typeof(b) _b = b; _a > _b ? _a : _b; })
+#define MIN(a,b)  ({ typeof(a) _a = a; typeof(b) _b = b; _a < _b ? _a : _b; })
+#define CLAMP(x, min, max) (MIN(MAX((x), (min)), (max)))
 
-// static void save_adjusted_datetime () {
+#define YEAR_MIN 1996
+#define YEAR_MAX 2095
 
-// }
+typedef enum {
+    RTC_EDIT_YEAR,
+    RTC_EDIT_MONTH,
+    RTC_EDIT_DAY,
+    RTC_EDIT_HOUR,
+    RTC_EDIT_MIN,
+    RTC_EDIT_SEC,
+} rtc_field_t;
+
+static const char* const DAYS_OF_WEEK[7] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
+
+static struct tm rtc_tm = {0};
+static bool is_editing_mode;
+static rtc_field_t editing_field_type;
+
+int wrap( uint16_t val, uint16_t min, uint16_t max ) {
+    if( val < min ) return max;
+    if( val > max ) return min;
+    return val;
+}
+
+rtc_time_t rtc_time_from_tm( struct tm *time ) {
+    return(rtc_time_t){
+        .year = CLAMP(time->tm_year + 1900, YEAR_MIN, YEAR_MAX),
+        .month = CLAMP(time->tm_mon, 1, 12),
+        .day = CLAMP(time->tm_mday, 1, 31),
+        .hour = CLAMP(time->tm_hour, 0, 23),
+        .min = CLAMP(time->tm_min, 0, 59),
+        .sec = CLAMP(time->tm_sec, 0, 59),
+        .week_day = CLAMP(time->tm_wday, 0, 6),
+    };
+}
+
+void adjust_rtc_time( struct tm *t, int incr ) {
+    switch(editing_field_type)
+    {
+        case RTC_EDIT_YEAR:
+            t->tm_year = wrap( t->tm_year + incr, YEAR_MIN - 1900, YEAR_MAX - 1900 );
+            break;
+        case RTC_EDIT_MONTH:
+            t->tm_mon = wrap( t->tm_mon + incr, 0, 11 );
+            break;
+        case RTC_EDIT_DAY:
+            t->tm_mday = wrap( t->tm_mday + incr, 1, 31 );
+            break;
+        case RTC_EDIT_HOUR:
+            t->tm_hour = wrap( t->tm_hour + incr, 0, 23 );
+            break;
+        case RTC_EDIT_MIN:
+            t->tm_min = wrap( t->tm_min + incr, 0, 59 );
+            break;
+        case RTC_EDIT_SEC:
+            t->tm_sec = wrap( t->tm_sec + incr, 0, 59 );
+            break;
+    }
+    // Recalculate day-of-week and day-of-year
+    time_t timestamp = mktime( t );
+    *t = *gmtime( &timestamp );
+}
+
+void component_editdatetime_draw ( struct tm t, rtc_field_t selected_field ) {
+    // FIXME: move this to components.c once improved.
+    /* Format RTC date/time as strings */
+    char full_dt[30];
+    char current_selection_chars[30];
+
+    snprintf( full_dt, sizeof(full_dt), ">%04d|%02d|%02d|%02d|%02d|%02d< %s",
+        t.tm_year + 1900,
+        t.tm_mon + 1,
+        t.tm_mday,
+        t.tm_hour,
+        t.tm_min,
+        t.tm_sec,
+        DAYS_OF_WEEK[t.tm_wday]
+        );
+
+    switch(selected_field)
+    {
+        // Note: for what ever reason, hat chars need to be duplicated to display correctly. This will be solved when there is a decent UI for it.
+        case RTC_EDIT_YEAR:
+            snprintf( current_selection_chars, sizeof(current_selection_chars), "*^^^^^^^^********************");
+            break;
+        case RTC_EDIT_MONTH:
+            snprintf( current_selection_chars, sizeof(current_selection_chars), "******^^^^*****************");
+            break;
+        case RTC_EDIT_DAY:
+            snprintf( current_selection_chars, sizeof(current_selection_chars), "*********^^^^**************");
+            break;
+        case RTC_EDIT_HOUR:
+            snprintf( current_selection_chars, sizeof(current_selection_chars), "************^^^^***********");
+            break;
+        case RTC_EDIT_MIN:
+            snprintf( current_selection_chars, sizeof(current_selection_chars), "***************^^^^********");
+            break;
+        case RTC_EDIT_SEC:
+            snprintf( current_selection_chars, sizeof(current_selection_chars), "******************^^^^*****");
+            break;
+    }
+        component_messagebox_draw(
+            "|YYYY|MM|DD|HH|MM|SS| DOW\n%s\n%s\n", full_dt, current_selection_chars);
+}
 
 static void process (menu_t *menu) {
-    if (menu->actions.back) {
+    if (menu->actions.back && !is_editing_mode) {
         sound_play_effect(SFX_EXIT);
         menu->next_mode = MENU_MODE_BROWSER;
     }
+    else if (menu->actions.enter && !is_editing_mode) {
+        rtc_tm = *gmtime(&menu->current_time);
+        is_editing_mode = true;
+    }
+
+    if (is_editing_mode) {
+        if (menu->actions.go_left) {
+            if ( editing_field_type <= RTC_EDIT_YEAR ) { editing_field_type = RTC_EDIT_SEC; }
+            else { editing_field_type = editing_field_type - 1; }
+        }
+        else if (menu->actions.go_right) {
+            if ( editing_field_type >= RTC_EDIT_SEC ) { editing_field_type = RTC_EDIT_YEAR; }
+            else { editing_field_type = editing_field_type + 1; }
+        }
+        else if (menu->actions.go_up) {
+            adjust_rtc_time( &rtc_tm, +1 );
+        }
+        else if (menu->actions.go_down) {
+            adjust_rtc_time( &rtc_tm, -1 );
+        }
+        else if (menu->actions.options) { // R button = save
+            if(rtc_is_writable()) {
+                // FIXME: settimeofday is not available in libdragon yet.
+                // struct timeval new_time = { .tv_sec = mktime(&rtc_tm) };
+                // int res = settimeofday(&new_time, NULL);
+
+                rtc_time_t rtc_time = rtc_time_from_tm(&rtc_tm);
+                int res = rtc_set(&rtc_time);
+                if (res != 1) {
+                    menu_show_error(menu, "Failed to set RTC time");
+                }
+            }
+            else {
+                menu_show_error(menu, "RTC is not writable");
+            }
+            is_editing_mode = false;
+        }
+        else if (menu->actions.back) { // cancel
+            is_editing_mode = false;
+        }
+    }
 }
 
 static void draw (menu_t *menu, surface_t *d) {
@@ -30,36 +169,51 @@ static void draw (menu_t *menu, surface_t *d) {
 
     component_layout_draw();
 
-	component_main_text_draw(
+    component_main_text_draw(
         ALIGN_CENTER, VALIGN_TOP,
         "ADJUST REAL TIME CLOCK\n"
         "\n"
         "\n"
-        "To set the date and time, please use the PC terminal\n"
-        "application and set via USB,\n or a N64 game with RTC support.\n\n"
-        "Current date & time: %s\n",
-        menu->current_time >= 0 ? ctime(&menu->current_time) : "Unknown\n"
-    );
-
-    component_main_text_draw(
-        ALIGN_LEFT, VALIGN_TOP,
-        "\n"
+        "To set the RTC date and time, Press A.\n"
+        "You can also use the PC terminal application via USB,\n"
+        "or even an N64 game with RTC support.\n"
         "\n"
+        "Current date & time: %s\n"
+        "\n",
+        menu->current_time >= 0 ? ctime(&menu->current_time) : "Unknown"
     );
 
+    if (!is_editing_mode) {
+        component_actions_bar_text_draw(
+            ALIGN_LEFT, VALIGN_TOP,
+            "A: Change\n"
+            "B: Back"
+        );
+    }
+    else {
+        component_actions_bar_text_draw(
+            ALIGN_RIGHT, VALIGN_TOP,
+            "Up/Down: Adjust Field\n"
+            "Left/Right: Switch Field"
+        );
+        component_actions_bar_text_draw(
+            ALIGN_LEFT, VALIGN_TOP,
+            "R: Save\n"
+            "B: Back"
+        );
+    }
 
-    component_actions_bar_text_draw(
-        ALIGN_LEFT, VALIGN_TOP,
-        "\n" // "A: Save\n"
-        "B: Back"
-    );
+    if (is_editing_mode) {
+        component_editdatetime_draw(rtc_tm, editing_field_type);
+    }
 
     rdpq_detach_show();
 }
 
 
 void view_rtc_init (menu_t *menu) {
-    // Nothing to initialize (yet)
+    is_editing_mode = false;
+    editing_field_type = RTC_EDIT_YEAR;
 }
 
 void view_rtc_display (menu_t *menu, surface_t *display) {

src/menu/views/system_info.c

@@ -57,7 +57,7 @@ static void draw (menu_t *menu, surface_t *d) {
         "Joypad 2 is %sconnected %s\n"
         "Joypad 3 is %sconnected %s\n"
         "Joypad 4 is %sconnected %s\n",
-        menu->current_time >= 0 ? ctime(&menu->current_time) : "Unknown\n",
+        menu->current_time >= 0 ? ctime(&menu->current_time) : "Unknown",
         is_memory_expanded() ? "" : "not ",
         (joypad[0]) ? "" : "not ", format_accessory(0),
         (joypad[1]) ? "" : "not ", format_accessory(1),