mermaid-go/pkg/renderer/er.go

// Package renderer provides rendering functionality for ER diagrams
package renderer

import (
	"fmt"
	"strings"

	"mermaid-go/pkg/ast"
)

// ERRenderer renders ER diagrams back to mermaid syntax
type ERRenderer struct{}

// NewERRenderer creates a new ER renderer
func NewERRenderer() *ERRenderer {
	return &ERRenderer{}
}

// Render renders an ER diagram to mermaid syntax
func (r *ERRenderer) Render(diagram *ast.ERDiagram) (string, error) {
	var builder strings.Builder

	// Start with diagram declaration
	builder.WriteString("erDiagram\n")

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

	// Note: ERDiagram doesn't have a Direction field in the existing structure
	// Direction support could be added to the AST if needed

	// Render entities with attributes
	for _, entity := range diagram.Entities {
		if len(entity.Attributes) > 0 {
			builder.WriteString("    ")
			builder.WriteString(entity.Name)
			builder.WriteString(" {\n")

			for _, attr := range entity.Attributes {
				builder.WriteString("        ")
				builder.WriteString(attr.Type)
				builder.WriteString(" ")
				builder.WriteString(attr.Name)

				// Add key if present
				if attr.Key != nil {
					builder.WriteString(" ")
					builder.WriteString(string(*attr.Key))
				}

				// Add comment if present
				if attr.Comment != nil {
					builder.WriteString(" \"")
					builder.WriteString(*attr.Comment)
					builder.WriteString("\"")
				}

				builder.WriteString("\n")
			}

			builder.WriteString("    }\n")
		}
	}

	// Render relationships
	for _, rel := range diagram.Relations {
		builder.WriteString("    ")
		builder.WriteString(rel.From)
		builder.WriteString(" ")
		builder.WriteString(string(rel.Type))
		builder.WriteString(" ")
		builder.WriteString(rel.To)

		if rel.Label != nil {
			builder.WriteString(" : ")
			if strings.Contains(*rel.Label, " ") {
				builder.WriteString(fmt.Sprintf("\"%s\"", *rel.Label))
			} else {
				builder.WriteString(*rel.Label)
			}
		}

		builder.WriteString("\n")
	}

	return builder.String(), nil
}