package render

import (
	"io"

	"github.com/osteele/liquid/expressions"
	"github.com/osteele/liquid/parser"
)

// Node is a node of the render tree.
type Node interface {
	SourceLocation() parser.SourceLoc // for error reporting
	SourceText() string               // for error reporting
	render(*trimWriter, nodeContext) Error
}

// BlockNode represents a {% tag %}…{% endtag %}.
type BlockNode struct {
	parser.Token
	renderer func(io.Writer, Context) error
	Body     []Node
	Clauses  []*BlockNode
}

// RawNode holds the text between the start and end of a raw tag.
type RawNode struct {
	slices []string
	sourcelessNode
}

// TagNode renders itself via a render function that is created during parsing.
type TagNode struct {
	parser.Token
	renderer func(io.Writer, Context) error
}

// TextNode is a text chunk, that is rendered verbatim.
type TextNode struct {
	parser.Token
}

// ObjectNode is an {{ object }} object.
type ObjectNode struct {
	parser.Token
	expr expressions.Expression
}

// SeqNode is a sequence of nodes.
type SeqNode struct {
	Children []Node
	sourcelessNode
}

// FIXME requiring this is a bad design
type sourcelessNode struct{}

func (n *sourcelessNode) SourceLocation() parser.SourceLoc {
	panic("unexpected call on sourceless node")
}

func (n *sourcelessNode) SourceText() string {
	panic("unexpected call on sourceless node")
}