/**
 * Copyright (c) 2026 Dominic Masters
 *
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include "uitextbox.h"
#include "assert/assert.h"
#include "util/memory.h"
#include "util/string.h"
#include "time/time.h"
#include "display/text/text.h"
#include "display/color.h"
#include "display/spritebatch/spritebatch.h"
#include "display/shader/shaderunlit.h"
#include "ui/frame/uiframe.h"

void uiTextboxInit(
  uitextbox_t *box,
  char_t *text,
  const uint32_t maxLength,
  uitextboxline_t *lines,
  const uint32_t linesMax
) {
  assertNotNull(box, "Textbox cannot be NULL");
  assertNotNull(text, "Text buffer cannot be NULL");
  assertTrue(maxLength >= 1, "maxLength must be at least 1");
  assertNotNull(lines, "Lines buffer cannot be NULL");
  assertTrue(linesMax >= 1, "linesMax must be at least 1");
  memoryZero(box, sizeof(uitextbox_t));
  box->text = text;
  box->maxLength = maxLength;
  box->lines = lines;
  box->linesMax = linesMax;
  box->glyphsBuiltForPage = -1;
}

void uiTextboxSetText(uitextbox_t *box, const char_t *text) {
  assertNotNull(box, "Textbox cannot be NULL");
  assertNotNull(text, "Text cannot be NULL");
  stringCopy(box->text, text, box->maxLength);
  box->currentPage = 0;
  box->scroll = 0;
  box->layoutWidth = 0.0f;
  box->layoutHeight = 0.0f;
  box->glyphsBuiltForPage = -1;
}

void uiTextboxBuildLayout(
  uitextbox_t *box,
  const float_t width,
  const float_t height
) {
  assertNotNull(box, "Textbox cannot be NULL");

  box->glyphsBuiltForPage = -1;
  box->layoutWidth = width;
  box->layoutHeight = height;
  box->lineCount = 0;
  box->pageCount = 1;

  float_t fontW = (float_t)FONT_DEFAULT.tileset->tileWidth;
  float_t fontH = (float_t)FONT_DEFAULT.tileset->tileHeight;

  if(fontW <= 0.0f || fontH <= 0.0f) return;

  box->charsPerLine = (int32_t)(width / fontW);
  box->linesPerPage = (int32_t)(height / (fontH + UI_TEXTBOX_LINE_SPACING));
  if(box->linesPerPage > UI_TEXTBOX_LINES_PER_PAGE_MAX) {
    box->linesPerPage = UI_TEXTBOX_LINES_PER_PAGE_MAX;
  }

  if(box->charsPerLine <= 0 || box->linesPerPage <= 0) return;
  if(box->text[0] == '\0') return;

  char_t *src = box->text;
  int32_t i = 0;

  while(src[i] != '\0' && box->lineCount < (int32_t)box->linesMax) {
    if(src[i] == '\t') {
      i++;
      int32_t rem = box->lineCount % box->linesPerPage;
      int32_t pad = rem > 0 ? box->linesPerPage - rem : 0;
      while(pad > 0 && box->lineCount < (int32_t)box->linesMax) {
        box->lines[box->lineCount].start = i;
        box->lines[box->lineCount].count = 0;
        box->lineCount++;
        pad--;
      }
      continue;
    }

    int32_t lineStart = i;
    int32_t lineWidth = 0;

    while(src[i] != '\0') {
      char_t c = src[i];

      if(c == '\n') { i++; break; }
      if(c == '\t') break;

      if(c == ' ') {
        int32_t wordLen = 0;
        int32_t j = i + 1;
        while(
          src[j] != ' ' && src[j] != '\n' &&
          src[j] != '\t' && src[j] != '\0'
        ) {
          wordLen++;
          j++;
        }

        if(lineWidth > 0 && lineWidth + 1 + wordLen > box->charsPerLine) {
          i++;
          break;
        }

        lineWidth++;
        i++;
      } else {
        if(lineWidth >= box->charsPerLine) break;
        lineWidth++;
        i++;
      }
    }

    box->lines[box->lineCount].start = lineStart;
    box->lines[box->lineCount].count = lineWidth;
    box->lineCount++;
  }

  if(box->lineCount == 0) {
    box->pageCount = 1;
  } else {
    box->pageCount =
      (box->lineCount + box->linesPerPage - 1) / box->linesPerPage;
  }
}

errorret_t uiTextboxUpdate(uitextbox_t *box) {
  assertNotNull(box, "Textbox cannot be NULL");

  #ifdef DUSK_TIME_DYNAMIC
    if(TIME.dynamicUpdate) errorOk();
  #endif

  if(!uiTextboxPageIsComplete(box)) {
    box->scroll += UI_TEXTBOX_SCROLL_CHARS_PER_TICK;
  }

  errorOk();
}

errorret_t uiTextboxDraw(
  uitextbox_t *box,
  const float_t x,
  const float_t y,
  const float_t width,
  const float_t height
) {
  assertNotNull(box, "Textbox cannot be NULL");

  float_t startX = (float_t)UI_FRAME_START_X;
  float_t startY = (float_t)UI_FRAME_START_Y;
  float_t contentX = x + startX;
  float_t contentY = y + startY;
  float_t contentW = width - 2.0f * startX;
  float_t contentH = height - 2.0f * startY;

  if(contentW != box->layoutWidth || contentH != box->layoutHeight) {
    uiTextboxBuildLayout(box, contentW, contentH);
  }

  errorChain(uiFrameDrawCached(&box->frameCache, x, y, width, height));

  if(box->lineCount == 0 || box->text[0] == '\0') errorOk();

  if(box->glyphsBuiltForPage != box->currentPage) {
    uiTextboxBuildPageGlyphs(box);
  }

  if(box->glyphCount == 0) errorOk();

  int32_t visibleCount = 0;
  while(
    visibleCount < box->glyphCount &&
    box->glyphs[visibleCount].revealAt <= box->scroll
  ) visibleCount++;

  if(visibleCount == 0) errorOk();

  spritebatchsprite_t scratch[UI_TEXTBOX_PAGE_GLYPHS_MAX];
  for(int32_t i = 0; i < visibleCount; i++) {
    scratch[i] = spriteBatchSpriteTranslate(
      &box->glyphs[i].sprite, contentX, contentY
    );
  }

  shadermaterial_t material = {
    .unlit = {
      .color = COLOR_WHITE,
      .texture = FONT_DEFAULT.texture
    }
  };
  errorChain(spriteBatchBuffer(scratch, visibleCount, &SHADER_UNLIT, material));

  errorOk();
}

void uiTextboxBuildPageGlyphs(uitextbox_t *box) {
  assertNotNull(box, "Textbox cannot be NULL");

  box->glyphCount = 0;

  int32_t pageFirst = box->currentPage * box->linesPerPage;
  int32_t pageLast = pageFirst + box->linesPerPage;
  if(pageLast > box->lineCount) pageLast = box->lineCount;

  float_t fontW = (float_t)FONT_DEFAULT.tileset->tileWidth;
  float_t fontH = (float_t)FONT_DEFAULT.tileset->tileHeight;

  int32_t consumed = 0;
  for(int32_t li = pageFirst; li < pageLast; li++) {
    uitextboxline_t *line = &box->lines[li];
    float_t lineY =
      (float_t)(li - pageFirst) * (fontH + UI_TEXTBOX_LINE_SPACING);

    for(int32_t ci = 0; ci < line->count; ci++) {
      consumed++;
      char_t c = box->text[line->start + ci];
      if(c == ' ') continue;

      assertTrue(
        box->glyphCount < UI_TEXTBOX_PAGE_GLYPHS_MAX,
        "Textbox page produces too many glyphs"
      );
      uitextboxglyph_t *glyph = &box->glyphs[box->glyphCount++];
      glyph->sprite = textGetSprite(
        (vec2){ (float_t)ci * fontW, lineY }, c, &FONT_DEFAULT
      );
      glyph->revealAt = consumed;
    }
  }

  box->glyphsBuiltForPage = box->currentPage;
}

int32_t uiTextboxGetPageCharCount(const uitextbox_t *box) {
  assertNotNull(box, "Textbox cannot be NULL");
  int32_t first = box->currentPage * box->linesPerPage;
  int32_t last = first + box->linesPerPage;
  if(last > box->lineCount) last = box->lineCount;
  int32_t total = 0;
  for(int32_t i = first; i < last; i++) {
    total += box->lines[i].count;
  }
  return total;
}

bool_t uiTextboxPageIsComplete(const uitextbox_t *box) {
  assertNotNull(box, "Textbox cannot be NULL");
  return box->scroll >= uiTextboxGetPageCharCount(box);
}

bool_t uiTextboxHasNextPage(const uitextbox_t *box) {
  assertNotNull(box, "Textbox cannot be NULL");
  return box->currentPage + 1 < box->pageCount;
}

void uiTextboxNextPage(uitextbox_t *box) {
  assertNotNull(box, "Textbox cannot be NULL");
  if(!uiTextboxHasNextPage(box)) return;
  box->currentPage++;
  box->scroll = 0;
}