//! Open-recursion AST visitor.
//!
//! Each `visit_*` method has a default body that calls the corresponding
//! `walk_*` free function, which in turn dispatches back into the trait.
//! Override any method to short-circuit or augment traversal — call the
//! matching `walk_*` from your override to keep descending.
//!
//! Pattern follows `rustc`'s and `syn`'s visitors.
//!
//! Read-only for now. A `VisitorMut` flavor can be added when transformations
//! become relevant.

use super::block::{
    BlockNode, BlockquoteNode, CommentNode, DefinitionItemNode, DefinitionListNode, ErrorNode,
    HeadingNode, HorizontalRuleNode, ListItemNode, ListNode, MathBlockNode, ParagraphNode,
    PreformattedNode, TableCellNode, TableNode, TableRowNode, TagNode,
};
use super::inline::{
    BoldItalicNode, BoldNode, CodeNode, ColorNode, InlineNode, ItalicNode, KeywordNode,
    MathInlineNode, StrikethroughNode, SubscriptNode, SuperscriptNode, TextNode,
};
use super::link::{ExternalLinkNode, RawUrlNode, TransclusionNode, WikiLinkNode};
use super::DocumentNode;

pub trait Visitor {
    // Top level
    fn visit_document(&mut self, node: &DocumentNode) {
        walk_document(self, node);
    }

    // Block dispatch
    fn visit_block(&mut self, node: &BlockNode) {
        walk_block(self, node);
    }

    // Inline dispatch
    fn visit_inline(&mut self, node: &InlineNode) {
        walk_inline(self, node);
    }

    // Block leaves and recursive block nodes
    fn visit_heading(&mut self, node: &HeadingNode) {
        for child in &node.children {
            self.visit_inline(child);
        }
    }
    fn visit_paragraph(&mut self, node: &ParagraphNode) {
        for child in &node.children {
            self.visit_inline(child);
        }
    }
    fn visit_horizontal_rule(&mut self, _node: &HorizontalRuleNode) {}
    fn visit_blockquote(&mut self, node: &BlockquoteNode) {
        for child in &node.children {
            self.visit_block(child);
        }
    }
    fn visit_preformatted(&mut self, _node: &PreformattedNode) {}
    fn visit_math_block(&mut self, _node: &MathBlockNode) {}
    fn visit_list(&mut self, node: &ListNode) {
        walk_list(self, node);
    }
    fn visit_list_item(&mut self, node: &ListItemNode) {
        walk_list_item(self, node);
    }
    fn visit_definition_list(&mut self, node: &DefinitionListNode) {
        for item in &node.items {
            self.visit_definition_item(item);
        }
    }
    fn visit_definition_item(&mut self, node: &DefinitionItemNode) {
        walk_definition_item(self, node);
    }
    fn visit_table(&mut self, node: &TableNode) {
        walk_table(self, node);
    }
    fn visit_table_row(&mut self, node: &TableRowNode) {
        walk_table_row(self, node);
    }
    fn visit_table_cell(&mut self, node: &TableCellNode) {
        for child in &node.children {
            self.visit_inline(child);
        }
    }
    fn visit_comment(&mut self, _node: &CommentNode) {}
    fn visit_tag(&mut self, _node: &TagNode) {}
    fn visit_error(&mut self, _node: &ErrorNode) {}

    // Inline leaves and recursive inline nodes
    fn visit_text(&mut self, _node: &TextNode) {}
    fn visit_bold(&mut self, node: &BoldNode) {
        for child in &node.children {
            self.visit_inline(child);
        }
    }
    fn visit_italic(&mut self, node: &ItalicNode) {
        for child in &node.children {
            self.visit_inline(child);
        }
    }
    fn visit_bold_italic(&mut self, node: &BoldItalicNode) {
        for child in &node.children {
            self.visit_inline(child);
        }
    }
    fn visit_strikethrough(&mut self, node: &StrikethroughNode) {
        for child in &node.children {
            self.visit_inline(child);
        }
    }
    fn visit_code(&mut self, _node: &CodeNode) {}
    fn visit_superscript(&mut self, node: &SuperscriptNode) {
        for child in &node.children {
            self.visit_inline(child);
        }
    }
    fn visit_subscript(&mut self, node: &SubscriptNode) {
        for child in &node.children {
            self.visit_inline(child);
        }
    }
    fn visit_math_inline(&mut self, _node: &MathInlineNode) {}
    fn visit_keyword(&mut self, _node: &KeywordNode) {}
    fn visit_color(&mut self, node: &ColorNode) {
        for child in &node.children {
            self.visit_inline(child);
        }
    }
    fn visit_wiki_link(&mut self, node: &WikiLinkNode) {
        if let Some(desc) = &node.description {
            for child in desc {
                self.visit_inline(child);
            }
        }
    }
    fn visit_external_link(&mut self, node: &ExternalLinkNode) {
        if let Some(desc) = &node.description {
            for child in desc {
                self.visit_inline(child);
            }
        }
    }
    fn visit_transclusion(&mut self, _node: &TransclusionNode) {}
    fn visit_raw_url(&mut self, _node: &RawUrlNode) {}
}

pub fn walk_document<V: Visitor + ?Sized>(v: &mut V, node: &DocumentNode) {
    for child in &node.children {
        v.visit_block(child);
    }
}

pub fn walk_block<V: Visitor + ?Sized>(v: &mut V, node: &BlockNode) {
    match node {
        BlockNode::Heading(n) => v.visit_heading(n),
        BlockNode::Paragraph(n) => v.visit_paragraph(n),
        BlockNode::HorizontalRule(n) => v.visit_horizontal_rule(n),
        BlockNode::Blockquote(n) => v.visit_blockquote(n),
        BlockNode::Preformatted(n) => v.visit_preformatted(n),
        BlockNode::MathBlock(n) => v.visit_math_block(n),
        BlockNode::List(n) => v.visit_list(n),
        BlockNode::DefinitionList(n) => v.visit_definition_list(n),
        BlockNode::Table(n) => v.visit_table(n),
        BlockNode::Comment(n) => v.visit_comment(n),
        BlockNode::Tag(n) => v.visit_tag(n),
        BlockNode::Error(n) => v.visit_error(n),
    }
}

pub fn walk_inline<V: Visitor + ?Sized>(v: &mut V, node: &InlineNode) {
    match node {
        InlineNode::Text(n) => v.visit_text(n),
        InlineNode::Bold(n) => v.visit_bold(n),
        InlineNode::Italic(n) => v.visit_italic(n),
        InlineNode::BoldItalic(n) => v.visit_bold_italic(n),
        InlineNode::Strikethrough(n) => v.visit_strikethrough(n),
        InlineNode::Code(n) => v.visit_code(n),
        InlineNode::Superscript(n) => v.visit_superscript(n),
        InlineNode::Subscript(n) => v.visit_subscript(n),
        InlineNode::MathInline(n) => v.visit_math_inline(n),
        InlineNode::Keyword(n) => v.visit_keyword(n),
        InlineNode::Color(n) => v.visit_color(n),
        InlineNode::WikiLink(n) => v.visit_wiki_link(n),
        InlineNode::ExternalLink(n) => v.visit_external_link(n),
        InlineNode::Transclusion(n) => v.visit_transclusion(n),
        InlineNode::RawUrl(n) => v.visit_raw_url(n),
    }
}

pub fn walk_list<V: Visitor + ?Sized>(v: &mut V, node: &ListNode) {
    for item in &node.items {
        v.visit_list_item(item);
    }
}

pub fn walk_list_item<V: Visitor + ?Sized>(v: &mut V, node: &ListItemNode) {
    for child in &node.children {
        v.visit_inline(child);
    }
    if let Some(sublist) = &node.sublist {
        v.visit_list(sublist);
    }
}

pub fn walk_definition_item<V: Visitor + ?Sized>(v: &mut V, node: &DefinitionItemNode) {
    if let Some(term) = &node.term {
        for child in term {
            v.visit_inline(child);
        }
    }
    for definition in &node.definitions {
        for child in definition {
            v.visit_inline(child);
        }
    }
}

pub fn walk_table<V: Visitor + ?Sized>(v: &mut V, node: &TableNode) {
    for row in &node.rows {
        v.visit_table_row(row);
    }
}

pub fn walk_table_row<V: Visitor + ?Sized>(v: &mut V, node: &TableRowNode) {
    for cell in &node.cells {
        v.visit_table_cell(cell);
    }
}