// Package renderer provides Sankey diagram rendering
package renderer

import (
	"fmt"
	"strings"

	"mermaid-go/pkg/ast"
)

// SankeyRenderer implements Sankey diagram rendering
type SankeyRenderer struct{}

// NewSankeyRenderer creates a new Sankey renderer
func NewSankeyRenderer() *SankeyRenderer {
	return &SankeyRenderer{}
}

// Render renders a Sankey diagram to mermaid syntax
func (r *SankeyRenderer) Render(diagram *ast.SankeyDiagram) (string, error) {
	var result strings.Builder

	// Start with sankey-beta keyword
	result.WriteString("sankey-beta\n")

	// Add title if present
	if diagram.Title != nil {
		result.WriteString(fmt.Sprintf("  title %s\n", *diagram.Title))
	}

	// Render nodes
	for _, node := range diagram.Nodes {
		result.WriteString(fmt.Sprintf("  %s\n", node.Label))
	}

	// Render links
	for _, link := range diagram.Links {
		result.WriteString(fmt.Sprintf("  %s --> %s : %d\n",
			link.Source, link.Target, link.Value))
	}

	return result.String(), nil
}