#import "RenderContext.h"
#import "RendererFactory.h"
#import "StyleConfig.h"

@implementation RenderContext

- (instancetype)init {
  self = [super init];
  if (self) {
    _attributeStack = [NSMutableArray new];
    _listDepth = 0;
    _orderedListIndex = 0;
    _currentListIsOrdered = NO;
    _currentListMaxMarkerDigits = 0;
    _isInsideBlockquote = NO;
    _isInsideCodeBlock = NO;
    _taskListIndex = 0;

    // Start with empty base; will be replaced when styleConfig is set
    [_attributeStack addObject:@{}];
  }
  return self;
}

- (void)setStyleConfig:(StyleConfig *)styleConfig {
  _styleConfig = styleConfig;

  // Reset the stack and push the `text` base style as the root attributes.
  // All subsequent renderers inherit these unless they override explicitly.
  [_attributeStack removeAllObjects];
  [_attributeStack
      addObject:[[self class] baseAttributesFromStyleConfig:styleConfig]];
}

+ (NSDictionary<NSAttributedStringKey, id> *)baseAttributesFromStyleConfig:
    (StyleConfig *)styleConfig {
  NSMutableDictionary *baseAttrs = [NSMutableDictionary new];

  MarkdownElementStyle *base = styleConfig.base;
  if (!base) return baseAttrs;

  UIFont *font = [base resolvedFont];
  if (font) {
    baseAttrs[NSFontAttributeName] = font;
  }

  if (base.color) {
    baseAttrs[NSForegroundColorAttributeName] = base.color;
  }

  // Note: lineHeight is applied per-block by ParagraphRenderer etc.
  // to avoid clipping elements with larger fonts (like headings).

  return [baseAttrs copy];
}

- (void)pushAttributes:(NSDictionary<NSAttributedStringKey, id> *)attrs {
  NSMutableDictionary *merged = [self.currentAttributes mutableCopy];
  [merged addEntriesFromDictionary:attrs];
  [_attributeStack addObject:[merged copy]];
}

- (void)popAttributes {
  if (_attributeStack.count > 1) {
    [_attributeStack removeLastObject];
  }
}

- (NSDictionary<NSAttributedStringKey, id> *)currentAttributes {
  return _attributeStack.lastObject ?: @{};
}

- (void)renderChildren:(ASTNodeWrapper *)node
                  into:(NSMutableAttributedString *)output {
  NSArray<ASTNodeWrapper *> *children = [node children];
  for (ASTNodeWrapper *child in children) {
    id<NodeRenderer> renderer = [RendererFactory rendererForNode:child];
    if (renderer) {
      [renderer renderNode:child into:output context:self];
    }
  }
}

+ (NSAttributedString *)renderNodeToAttributedString:(ASTNodeWrapper *)node
                                         styleConfig:(StyleConfig *)styleConfig
                                          customTags:
                                              (NSArray<NSString *> *)customTags {
  return [self renderNodeToAttributedString:node
                                styleConfig:styleConfig
                                 customTags:customTags
                             inheritedAttrs:nil];
}

+ (NSAttributedString *)renderNodeToAttributedString:(ASTNodeWrapper *)node
                                         styleConfig:(StyleConfig *)styleConfig
                                          customTags:
                                              (NSArray<NSString *> *)customTags
                                      inheritedAttrs:
                                          (NSDictionary<NSAttributedStringKey,
                                                        id> *)inheritedAttrs {
  RenderContext *context = [[RenderContext alloc] init];
  context.styleConfig = styleConfig;
  context.customTags = [NSSet setWithArray:customTags];

  if (inheritedAttrs) {
    [context.attributeStack removeAllObjects];
    [context.attributeStack addObject:[inheritedAttrs copy]];
  }

  NSMutableAttributedString *output = [[NSMutableAttributedString alloc] init];
  id<NodeRenderer> renderer = [RendererFactory rendererForNode:node];
  if (renderer) {
    [renderer renderNode:node into:output context:context];
  }

  [self trimTrailingNewlines:output];

  return [output copy];
}

/// Trims trailing newline characters from an attributed string in a
/// single ranged delete instead of char-by-char.
+ (void)trimTrailingNewlines:(NSMutableAttributedString *)output {
  NSString *str = output.string;
  NSUInteger len = str.length;
  if (len == 0) return;

  NSUInteger end = len;
  while (end > 0 && [str characterAtIndex:end - 1] == '\n') {
    --end;
  }
  if (end < len) {
    [output deleteCharactersInRange:NSMakeRange(end, len - end)];
  }
}

+ (NSAttributedString *)renderListItemContent:(ASTNodeWrapper *)item
                                    isOrdered:(BOOL)isOrdered
                                 orderedIndex:(NSInteger)orderedIndex
                              maxMarkerDigits:(NSInteger)maxMarkerDigits
                                  styleConfig:(StyleConfig *)styleConfig
                                   customTags:(NSArray<NSString *> *)customTags
                               inheritedAttrs:
                                   (NSDictionary<NSAttributedStringKey, id> *)
                                       inheritedAttrs {
  RenderContext *context = [[RenderContext alloc] init];
  context.styleConfig = styleConfig;
  context.customTags = [NSSet setWithArray:customTags];
  context.orderedListIndex = orderedIndex;
  context.currentListIsOrdered = isOrdered;
  context.currentListMaxMarkerDigits = maxMarkerDigits;
  context.listDepth = 1;

  if (inheritedAttrs) {
    [context.attributeStack removeAllObjects];
    [context.attributeStack addObject:[inheritedAttrs copy]];
  }

  NSMutableAttributedString *output = [[NSMutableAttributedString alloc] init];
  id<NodeRenderer> renderer = [RendererFactory rendererForNode:item];
  if (renderer) {
    [renderer renderNode:item into:output context:context];
  }

  [self trimTrailingNewlines:output];

  return [output copy];
}

@end