// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: MIT

package markdown

// nodeKind identifies a block node of the document tree.
type nodeKind uint8

const (
	kindDocument nodeKind = iota
	kindParagraph
	kindHeading
	kindCodeBlock
	kindHTMLBlock
	kindBlockquote
	kindList
	kindListItem
	kindThematicBreak
	kindTable
	kindFootnoteDef
	kindDefList
	kindDefTerm
	kindDefItem
)

// listKind distinguishes bullet lists from ordered lists.
type listKind uint8

const (
	bulletList listKind = iota
	orderedList
)

// Column alignment of a table, carried per column.
const (
	alignNone uint8 = iota
	alignLeft
	alignCentre
	alignRight
)

// Node is one block of the parsed document. The zero value is a document
// root; every other kind is created by the parser.
type Node struct {
	kind     nodeKind
	parent   *Node
	children []*Node

	// content holds the raw text of a leaf block: paragraph or heading
	// inline text, code source, or the lines of an HTML block.
	content []byte

	level int // heading level, 1 to 6

	fenced      bool // code block opened by a fence
	fenceChar   byte // fence character, '`' or '~'
	fenceLength int  // length of the opening fence
	fenceOffset int  // columns of indentation before the opening fence
	info        string

	htmlType int // HTML block start condition, 1 to 7

	listKind     listKind
	bulletChar   byte // bullet list: the marker character
	delimiter    byte // ordered list: '.' or ')'
	start        int  // ordered list: number of the first item
	tight        bool
	markerOffset int // item: indentation of the marker inside its container
	padding      int // item: columns from the marker start to the content

	// refs collects the link reference definitions of the document; it is
	// carried by the root node only.
	refs map[string]reference

	// footnotes collects the footnote definitions of the document, in
	// document order; it is carried by the root node only. The renderer
	// orders the rendered section by reference.
	footnotes []*Node

	// label names a footnote definition.
	label string

	// table columns and rows, cells as raw inline content.
	align  []uint8
	header [][]byte
	rows   [][][]byte

	task     bool // item: the first paragraph begins with a task marker
	taskDone bool

	startLine int

	lastLineBlank   bool
	lastLineChecked bool
	finalised       bool
}

// reference is one link reference definition of the document.
type reference struct {
	destination string
	title       string
	hasTitle    bool
}

// canContain reports whether parent accepts child blocks of the given kind.
func canContain(parent, child nodeKind) bool {
	switch parent {
	case kindDocument, kindBlockquote, kindListItem, kindDefItem, kindFootnoteDef:
		return child != kindDocument
	case kindList:
		return child == kindListItem
	case kindDefList:
		return child == kindDefTerm || child == kindDefItem || child == kindParagraph
	}
	return false
}