package parser

import (
	"fmt"
	"path/filepath"
	"strings"
)

// Parser interface for all document parsers.
type Parser interface {
	SupportedExtensions() []string
	ParseToMarkdown(path string) (string, error)
}

// Registry holds registered parsers keyed by extension.
type Registry struct {
	parsers map[string]Parser
}

// NewRegistry creates a parser registry with all built-in parsers.
func NewRegistry() *Registry {
	r := &Registry{parsers: make(map[string]Parser)}
	r.Register(&ExcelParser{})
	r.Register(&PDFParser{})
	r.Register(&CADParser{})
	r.Register(&WordParser{})
	return r
}

// Register adds a parser for its supported extensions.
func (r *Registry) Register(p Parser) {
	for _, ext := range p.SupportedExtensions() {
		r.parsers[strings.ToLower(ext)] = p
	}
}

// Parse dispatches to the appropriate parser based on file extension.
func (r *Registry) Parse(path string) (string, error) {
	ext := strings.ToLower(filepath.Ext(path))
	p, ok := r.parsers[ext]
	if !ok {
		return "", fmt.Errorf("unsupported file type: %s", ext)
	}
	return p.ParseToMarkdown(path)
}