dusk/archive/dusk/ui/uitextbox.c

/**
 * Copyright (c) 2025 Dominic Masters
 * 
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include "uitextbox.h"
#include "util/memory.h"
#include "assert/assert.h"
#include "input.h"

uitextbox_t UI_TEXTBOX;

void uiTextboxInit() {
  memoryZero(&UI_TEXTBOX, sizeof(uitextbox_t));
}

void uiTextboxUpdate() {
  if(UI_TEXTBOX.visible == false) return;

  if(UI_TEXTBOX.charsRevealed < UI_TEXTBOX.pageChars[UI_TEXTBOX.page]) {
    UI_TEXTBOX.charsRevealed++;
    if(inputIsDown(INPUT_BIND_ACTION)) {
      UI_TEXTBOX.charsRevealed++;
    }

  } else {
    if(inputPressed(INPUT_BIND_ACTION)) {
      if(UI_TEXTBOX.page < UI_TEXTBOX.pageCount - 1) {
        UI_TEXTBOX.page++;
        UI_TEXTBOX.charsRevealed = 0;
      } else {
        // Close the textbox
        UI_TEXTBOX.visible = false;
        UI_TEXTBOX.page = 0;
        UI_TEXTBOX.charsRevealed = 0;
      }
    }
  }
}

void uiTextboxSetText(const char_t *text) {
  assertNotNull(text, "Text pointer cannot be NULL, call uiTextboxClose()");
  
  memoryZero(UI_TEXTBOX.text, sizeof(UI_TEXTBOX.text));
  memoryZero(UI_TEXTBOX.lineLengths, sizeof(UI_TEXTBOX.lineLengths));
  memoryZero(UI_TEXTBOX.pageChars, sizeof(UI_TEXTBOX.pageChars));
  UI_TEXTBOX.pageCount = 1;// Always at least one page.
  UI_TEXTBOX.totalChars = 0;
  UI_TEXTBOX.page = 0;
  UI_TEXTBOX.charsRevealed = 0;
  UI_TEXTBOX.visible = true;
  
  char_t c;// current char
  uint16_t i = 0;// Index of character we are pulling
  uint16_t lastWordStart = 0;// Index of the last word start (in src string).
  uint8_t line = 0;// Which line we are currently writing to.
  uint8_t page = 0;
  bool_t startOfLine = true;// Are we at the start of a line?

  while((c = text[i++]) != '\0') {
    // HARD disallowed characters.
    assertTrue(c != '\r', "Carriage return characters not allowed.");
    assertTrue(c != '\t', "Tab characters not allowed.");
  
    // Is this the beginning of a new line?
    if(startOfLine) {
      // Yes, we are at the start of a new line.
      startOfLine = false;
      // Is this the first line?
      if(line == 0) {
        // nothing to do, just continue.
      } else {
        // Yes, start of new line. Is this line the first line on a new page?
        if((line % UI_TEXTBOX_LINES_PER_PAGE) == 0) {
          // Yes, start a new page.
          i--;// Rewind so that this character can go through the loop again.
          goto newPage;
        }
      }
    }

    // Change what we do depending on the character.
    if(c == '\n') {
      goto newline;
    } else if(c == ' ') {
      goto whitespace;
    } else {
      goto character;
    }

    // Handle whitespace characters (not newlines)
    whitespace: {
      // Is this whitespace the last char of the line?
      if(UI_TEXTBOX.lineLengths[line] == UI_TEXTBOX_CHARS_PER_LINE) {
        goto newline;
      } else if(UI_TEXTBOX.lineLengths[line] == 0) {
        // If this is the first character of the line, we can just ignore it.
        continue;
      }
      
      lastWordStart = i;
      goto appendCharacter;
    }

    // Handle regular characters
    character: {
      // Is this character going to cause a wrap to occur?
      if(UI_TEXTBOX.lineLengths[line] == UI_TEXTBOX_CHARS_PER_LINE) {
        // How long ago was the last whitespace?
        uint16_t charsSinceLastSpace = i - lastWordStart;

        // Is the word longer than a line can possibly hold?
        assertTrue(
          charsSinceLastSpace < UI_TEXTBOX_CHARS_PER_LINE,
          "Word longer than a line can hold."
        );

        // Undo appending of all characters since the last whitespace.
        UI_TEXTBOX.totalChars -= charsSinceLastSpace;
        UI_TEXTBOX.lineLengths[line] -= charsSinceLastSpace;
        UI_TEXTBOX.pageChars[page] -= charsSinceLastSpace;

        // Rewind the loop so that printing will begin on the new line at the
        // start of the last word.
        i -= charsSinceLastSpace;

        // Newline.
        goto newline;
      }
      
      // Append the character to the textbox.
      goto appendCharacter;
    }

    // Handle newlines
    newline: {
      // Ensure we don't exceed the maximum number of lines.
      assertTrue(
        line < UI_TEXTBOX_LINE_COUNT,
        "Exceeded maximum number of lines in textbox."
      );

      // Add a line to the textbox.
      line++;
      startOfLine = true;// Next iteration will be a start of line.
      lastWordStart = i;// We also mark this as the last word start.
      continue;
    }

    newPage: {
      // Make sure we don't exceed the maximum number of pages.
      assertTrue(
        UI_TEXTBOX.pageCount < UI_TEXTBOX_PAGE_COUNT_MAX,
        "Exceeded maximum number of pages in textbox."
      );
      UI_TEXTBOX.pageCount++;
      page++;
      continue;
    }

    appendCharacter: {
      assertTrue(
        UI_TEXTBOX.totalChars < UI_TEXTBOX_CHARS_MAX,
        "Exceeded maximum number of characters in textbox."
      );
      assertTrue(
        line < UI_TEXTBOX_LINE_COUNT,
        "Exceeded maximum number of lines in textbox."
      );
      assertTrue(
        UI_TEXTBOX.lineLengths[line] < UI_TEXTBOX_CHARS_PER_LINE,
        "Exceeded maximum number of chars per line in textbox."
      );

      // Push the character to the textbox.
      UI_TEXTBOX.text[
        line * UI_TEXTBOX_CHARS_PER_LINE + UI_TEXTBOX.lineLengths[line]
      ] = c;

      // Increment the line length and page character count.
      UI_TEXTBOX.totalChars++;
      UI_TEXTBOX.lineLengths[line]++;
      UI_TEXTBOX.pageChars[page]++;
      continue;
    }

    assertUnreachable("Code should not reach here, all cases handled.");
  }
}