mermaid-go/pkg/parser/mermaid.go

// Package parser provides the main parser router for all diagram types
package parser

import (
	"fmt"
	"strings"

	"mermaid-go/pkg/ast"
)

// MermaidParser is the main parser that routes to specific diagram parsers
type MermaidParser struct{}

// NewMermaidParser creates a new main mermaid parser
func NewMermaidParser() *MermaidParser {
	return &MermaidParser{}
}

// Parse parses a mermaid diagram string and returns the appropriate AST
func (p *MermaidParser) Parse(input string) (ast.Diagram, error) {
	// Detect diagram type from the input
	diagramType := p.detectDiagramType(input)

	switch diagramType {
	case ast.DiagramTypeFlowchart:
		parser := NewFlowchartParser()
		return parser.Parse(input)
	case ast.DiagramTypeSequence:
		parser := NewSequenceParser()
		return parser.Parse(input)
	case ast.DiagramTypeClassDiagram:
		parser := NewClassParser()
		return parser.Parse(input)
	case ast.DiagramTypeStateDiagram:
		parser := NewStateParser()
		return parser.Parse(input)
	case ast.DiagramTypePie:
		parser := NewPieParser()
		return parser.Parse(input)
	case ast.DiagramTypeERDiagram:
		parser := NewERParser()
		return parser.Parse(input)
	default:
		return nil, fmt.Errorf("unsupported diagram type: %s", diagramType)
	}
}

// detectDiagramType analyzes the input to determine the diagram type
func (p *MermaidParser) detectDiagramType(input string) ast.DiagramType {
	// Clean input and get first meaningful line
	lines := strings.Split(input, "\n")

	for _, line := range lines {
		line = strings.TrimSpace(line)
		if line == "" || strings.HasPrefix(line, "%%") {
			continue // Skip empty lines and comments
		}

		// Check for explicit diagram type declarations
		lowerLine := strings.ToLower(line)

		if strings.HasPrefix(lowerLine, "sequencediagram") {
			return ast.DiagramTypeSequence
		}
		if strings.HasPrefix(lowerLine, "classdiagram") {
			return ast.DiagramTypeClassDiagram
		}
		if strings.HasPrefix(lowerLine, "statediagram") {
			return ast.DiagramTypeStateDiagram
		}
		if strings.HasPrefix(lowerLine, "flowchart") ||
			strings.HasPrefix(lowerLine, "graph") {
			return ast.DiagramTypeFlowchart
		}
		if strings.HasPrefix(lowerLine, "erdiagram") {
			return ast.DiagramTypeERDiagram
		}
		if strings.HasPrefix(lowerLine, "journey") {
			return ast.DiagramTypeUserJourney
		}
		if strings.HasPrefix(lowerLine, "timeline") {
			return ast.DiagramTypeTimeline
		}
		if strings.HasPrefix(lowerLine, "gantt") {
			return ast.DiagramTypeGantt
		}
		if strings.HasPrefix(lowerLine, "pie") {
			return ast.DiagramTypePie
		}
		if strings.HasPrefix(lowerLine, "quadrantchart") {
			return ast.DiagramTypeQuadrant
		}
		if strings.HasPrefix(lowerLine, "requirementdiagram") {
			return ast.DiagramTypeRequirement
		}
		if strings.HasPrefix(lowerLine, "block") {
			return ast.DiagramTypeBlock
		}

		// If no explicit type found, try to infer from content
		// This is a fallback for diagrams without explicit type declarations

		// Look for sequence diagram patterns
		if strings.Contains(lowerLine, "participant") ||
			strings.Contains(lowerLine, "actor") ||
			strings.Contains(lowerLine, "-->") ||
			strings.Contains(lowerLine, "->>") {
			return ast.DiagramTypeSequence
		}

		// Look for class diagram patterns
		if strings.Contains(lowerLine, "class ") ||
			strings.Contains(lowerLine, "--|>") ||
			strings.Contains(lowerLine, "--*") ||
			strings.Contains(lowerLine, "--o") {
			return ast.DiagramTypeClassDiagram
		}

		// Look for state diagram patterns
		if strings.Contains(lowerLine, "[*]") ||
			strings.Contains(lowerLine, "state ") {
			return ast.DiagramTypeStateDiagram
		}

		// Default to flowchart for backwards compatibility
		break
	}

	// Default fallback
	return ast.DiagramTypeFlowchart
}

// ParseWithType forces parsing with a specific diagram type
func (p *MermaidParser) ParseWithType(input string, diagramType ast.DiagramType) (ast.Diagram, error) {
	switch diagramType {
	case ast.DiagramTypeFlowchart:
		parser := NewFlowchartParser()
		return parser.Parse(input)
	case ast.DiagramTypeSequence:
		parser := NewSequenceParser()
		return parser.Parse(input)
	case ast.DiagramTypeClassDiagram:
		parser := NewClassParser()
		return parser.Parse(input)
	case ast.DiagramTypeStateDiagram:
		parser := NewStateParser()
		return parser.Parse(input)
	case ast.DiagramTypePie:
		parser := NewPieParser()
		return parser.Parse(input)
	case ast.DiagramTypeERDiagram:
		parser := NewERParser()
		return parser.Parse(input)
	default:
		return nil, fmt.Errorf("unsupported diagram type: %s", diagramType)
	}
}