package parser

import (
	"fmt"
	"regexp"
)

type RegexParser struct {
	re *regexp.Regexp
}

func NewRegexParser(pattern string) (*RegexParser, error) {
	re, err := regexp.Compile(pattern)
	if err != nil {
		return nil, fmt.Errorf("compile regex pattern: %w", err)
	}
	return &RegexParser{re: re}, nil
}

func (p *RegexParser) Parse(body []byte) (*ParsedMessage, error) {
	matches := p.re.FindStringSubmatch(string(body))
	if matches == nil {
		return nil, fmt.Errorf("regex: body does not match pattern")
	}

	names := p.re.SubexpNames()
	data := make(map[string]interface{})
	var event string

	for i, name := range names {
		if i == 0 || name == "" {
			continue
		}
		if name == "event" {
			event = matches[i]
		} else {
			data[name] = matches[i]
		}
	}

	return &ParsedMessage{
		Event: event,
		Data:  data,
		Body:  string(body),
	}, nil
}