/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

#import "RCTAttributedTextUtils.h"

#include <react/core/LayoutableShadowNode.h>
#include <react/textlayoutmanager/RCTFontProperties.h>
#include <react/textlayoutmanager/RCTFontUtils.h>
#include <react/textlayoutmanager/RCTTextPrimitivesConversions.h>

using namespace facebook::react;

@implementation RCTWeakEventEmitterWrapper {
  std::weak_ptr<const EventEmitter> _weakEventEmitter;
}

- (void)setEventEmitter:(SharedEventEmitter)eventEmitter
{
  _weakEventEmitter = eventEmitter;
}

- (SharedEventEmitter)eventEmitter
{
  return _weakEventEmitter.lock();
}

- (void)dealloc
{
  _weakEventEmitter.reset();
}

@end

inline static UIFontWeight RCTUIFontWeightFromInteger(NSInteger fontWeight)
{
  assert(fontWeight > 50);
  assert(fontWeight < 950);

  static UIFontWeight weights[] = {/* ~100 */ UIFontWeightUltraLight,
                                   /* ~200 */ UIFontWeightThin,
                                   /* ~300 */ UIFontWeightLight,
                                   /* ~400 */ UIFontWeightRegular,
                                   /* ~500 */ UIFontWeightMedium,
                                   /* ~600 */ UIFontWeightSemibold,
                                   /* ~700 */ UIFontWeightBold,
                                   /* ~800 */ UIFontWeightHeavy,
                                   /* ~900 */ UIFontWeightBlack};
  // The expression is designed to convert something like 760 or 830 to 7.
  return weights[(fontWeight + 50) / 100 - 1];
}

inline static UIFont *RCTEffectiveFontFromTextAttributes(const TextAttributes &textAttributes)
{
  NSString *fontFamily = [NSString stringWithCString:textAttributes.fontFamily.c_str() encoding:NSUTF8StringEncoding];

  RCTFontProperties fontProperties;
  fontProperties.family = fontFamily;
  fontProperties.size = textAttributes.fontSize;
  fontProperties.style = textAttributes.fontStyle.hasValue()
      ? RCTFontStyleFromFontStyle(textAttributes.fontStyle.value())
      : RCTFontStyleUndefined;
  fontProperties.variant = textAttributes.fontVariant.hasValue()
      ? RCTFontVariantFromFontVariant(textAttributes.fontVariant.value())
      : RCTFontVariantUndefined;
  fontProperties.weight = textAttributes.fontWeight.hasValue()
      ? RCTUIFontWeightFromInteger((NSInteger)textAttributes.fontWeight.value())
      : NAN;
  fontProperties.sizeMultiplier = textAttributes.fontSizeMultiplier;

  return RCTFontWithFontProperties(fontProperties);
}

inline static CGFloat RCTEffectiveFontSizeMultiplierFromTextAttributes(const TextAttributes &textAttributes)
{
  return textAttributes.allowFontScaling.value_or(true) && !isnan(textAttributes.fontSizeMultiplier)
      ? textAttributes.fontSizeMultiplier
      : 1.0;
}

inline static UIColor *RCTEffectiveForegroundColorFromTextAttributes(const TextAttributes &textAttributes)
{
  UIColor *effectiveForegroundColor = RCTUIColorFromSharedColor(textAttributes.foregroundColor) ?: [UIColor blackColor];

  if (!isnan(textAttributes.opacity)) {
    effectiveForegroundColor = [effectiveForegroundColor
        colorWithAlphaComponent:CGColorGetAlpha(effectiveForegroundColor.CGColor) * textAttributes.opacity];
  }

  return effectiveForegroundColor;
}

inline static UIColor *RCTEffectiveBackgroundColorFromTextAttributes(const TextAttributes &textAttributes)
{
  UIColor *effectiveBackgroundColor = RCTUIColorFromSharedColor(textAttributes.backgroundColor);

  if (effectiveBackgroundColor && !isnan(textAttributes.opacity)) {
    effectiveBackgroundColor = [effectiveBackgroundColor
        colorWithAlphaComponent:CGColorGetAlpha(effectiveBackgroundColor.CGColor) * textAttributes.opacity];
  }

  return effectiveBackgroundColor ?: [UIColor clearColor];
}

static NSDictionary<NSAttributedStringKey, id> *RCTNSTextAttributesFromTextAttributes(
    const TextAttributes &textAttributes)
{
  NSMutableDictionary<NSAttributedStringKey, id> *attributes = [NSMutableDictionary dictionaryWithCapacity:10];

  // Font
  UIFont *font = RCTEffectiveFontFromTextAttributes(textAttributes);
  if (font) {
    attributes[NSFontAttributeName] = font;
  }

  // Colors
  UIColor *effectiveForegroundColor = RCTEffectiveForegroundColorFromTextAttributes(textAttributes);

  if (textAttributes.foregroundColor || !isnan(textAttributes.opacity)) {
    attributes[NSForegroundColorAttributeName] = effectiveForegroundColor;
  }

  if (textAttributes.backgroundColor || !isnan(textAttributes.opacity)) {
    attributes[NSBackgroundColorAttributeName] = RCTEffectiveBackgroundColorFromTextAttributes(textAttributes);
  }

  // Kerning
  if (!isnan(textAttributes.letterSpacing)) {
    attributes[NSKernAttributeName] = @(textAttributes.letterSpacing);
  }

  // Paragraph Style
  NSMutableParagraphStyle *paragraphStyle = [NSMutableParagraphStyle new];
  BOOL isParagraphStyleUsed = NO;
  if (textAttributes.alignment.hasValue()) {
    TextAlignment textAlignment = textAttributes.alignment.value_or(TextAlignment::Natural);
    if (textAttributes.layoutDirection.value_or(LayoutDirection::LeftToRight) == LayoutDirection::RightToLeft) {
      if (textAlignment == TextAlignment::Right) {
        textAlignment = TextAlignment::Left;
      } else if (textAlignment == TextAlignment::Left) {
        textAlignment = TextAlignment::Right;
      }
    }

    paragraphStyle.alignment = RCTNSTextAlignmentFromTextAlignment(textAlignment);
    isParagraphStyleUsed = YES;
  }

  if (textAttributes.baseWritingDirection.hasValue()) {
    paragraphStyle.baseWritingDirection =
        RCTNSWritingDirectionFromWritingDirection(textAttributes.baseWritingDirection.value());
    isParagraphStyleUsed = YES;
  }

  if (!isnan(textAttributes.lineHeight)) {
    CGFloat lineHeight = textAttributes.lineHeight * RCTEffectiveFontSizeMultiplierFromTextAttributes(textAttributes);
    paragraphStyle.minimumLineHeight = lineHeight;
    paragraphStyle.maximumLineHeight = lineHeight;
    isParagraphStyleUsed = YES;
  }

  if (isParagraphStyleUsed) {
    attributes[NSParagraphStyleAttributeName] = paragraphStyle;
  }

  // Decoration
  if (textAttributes.textDecorationLineType.value_or(TextDecorationLineType::None) != TextDecorationLineType::None) {
    auto textDecorationLineType = textAttributes.textDecorationLineType.value();

    NSUnderlineStyle style = RCTNSUnderlineStyleFromStyleAndPattern(
        textAttributes.textDecorationLineStyle.value_or(TextDecorationLineStyle::Single),
        textAttributes.textDecorationLinePattern.value_or(TextDecorationLinePattern::Solid));

    UIColor *textDecorationColor = RCTUIColorFromSharedColor(textAttributes.textDecorationColor);

    // Underline
    if (textDecorationLineType == TextDecorationLineType::Underline ||
        textDecorationLineType == TextDecorationLineType::UnderlineStrikethrough) {
      attributes[NSUnderlineStyleAttributeName] = @(style);

      if (textDecorationColor) {
        attributes[NSUnderlineColorAttributeName] = textDecorationColor;
      }
    }

    // Strikethrough
    if (textDecorationLineType == TextDecorationLineType::Strikethrough ||
        textDecorationLineType == TextDecorationLineType::UnderlineStrikethrough) {
      attributes[NSStrikethroughStyleAttributeName] = @(style);

      if (textDecorationColor) {
        attributes[NSStrikethroughColorAttributeName] = textDecorationColor;
      }
    }
  }

  // Shadow
  if (textAttributes.textShadowOffset.hasValue()) {
    auto textShadowOffset = textAttributes.textShadowOffset.value();
    NSShadow *shadow = [NSShadow new];
    shadow.shadowOffset = CGSize{textShadowOffset.width, textShadowOffset.height};
    shadow.shadowBlurRadius = textAttributes.textShadowRadius;
    shadow.shadowColor = RCTUIColorFromSharedColor(textAttributes.textShadowColor);
    attributes[NSShadowAttributeName] = shadow;
  }

  // Special
  if (textAttributes.isHighlighted) {
    attributes[RCTAttributedStringIsHighlightedAttributeName] = @YES;
  }

  return [attributes copy];
}

NSAttributedString *RCTNSAttributedStringFromAttributedString(const AttributedString &attributedString)
{
  NSMutableAttributedString *nsAttributedString = [[NSMutableAttributedString alloc] init];

  [nsAttributedString beginEditing];

  for (auto fragment : attributedString.getFragments()) {
    NSAttributedString *nsAttributedStringFragment;

    auto layoutMetrics = fragment.shadowView.layoutMetrics;

    if (layoutMetrics != EmptyLayoutMetrics) {
      CGRect bounds = {.origin = {.x = layoutMetrics.frame.origin.x, .y = layoutMetrics.frame.origin.y},
                       .size = {.width = layoutMetrics.frame.size.width, .height = layoutMetrics.frame.size.height}};

      NSTextAttachment *attachment = [NSTextAttachment new];
      attachment.bounds = bounds;

      nsAttributedStringFragment = [NSAttributedString attributedStringWithAttachment:attachment];
    } else {
      NSString *string = [NSString stringWithCString:fragment.string.c_str() encoding:NSUTF8StringEncoding];

      nsAttributedStringFragment =
          [[NSAttributedString alloc] initWithString:string
                                          attributes:RCTNSTextAttributesFromTextAttributes(fragment.textAttributes)];
    }

    NSMutableAttributedString *nsMutableAttributedStringFragment =
        [[NSMutableAttributedString alloc] initWithAttributedString:nsAttributedStringFragment];

    if (fragment.parentShadowView.componentHandle) {
      RCTWeakEventEmitterWrapper *eventEmitterWrapper = [RCTWeakEventEmitterWrapper new];
      eventEmitterWrapper.eventEmitter = fragment.parentShadowView.eventEmitter;

      NSDictionary<NSAttributedStringKey, id> *additionalTextAttributes =
          @{RCTAttributedStringEventEmitterKey : eventEmitterWrapper};

      [nsMutableAttributedStringFragment addAttributes:additionalTextAttributes
                                                 range:NSMakeRange(0, nsMutableAttributedStringFragment.length)];
    }

    [nsAttributedString appendAttributedString:nsMutableAttributedStringFragment];
  }

  [nsAttributedString endEditing];

  return nsAttributedString;
}
