parser.go

package main

import (
	"encoding/json"
	"regexp"
	"strings"
)

// PackageJSON struct to map only necessary fields
type PackageJSON struct {
	Dependencies    map[string]string `json:"dependencies"`
	DevDependencies map[string]string `json:"devDependencies"`
}

// ParsePackageJSON extracts package names from package.json content
func ParsePackageJSON(content []byte) ([]string, error) {
	var pkg PackageJSON
	if err := json.Unmarshal(content, &pkg); err != nil {
		return nil, err
	}

	var packages []string
	for k := range pkg.Dependencies {
		packages = append(packages, k)
	}
	for k := range pkg.DevDependencies {
		packages = append(packages, k)
	}

	return Deduplicate(packages), nil
}

// ParseYarnLock extracts package names from yarn.lock content
func ParseYarnLock(content []byte) ([]string, error) {
	// Yarn lock entries look like: "package-name@version":
	// Regex to capture the package name at the start of the line or structure
	// This is a simplified regex effectively capturing "string@" or "@scope/string@"
	re := regexp.MustCompile(`^"?(@?[a-zA-Z0-9.\-\/]+)@`)
	
	lines := strings.Split(string(content), "\n")
	var packages []string

	for _, line := range lines {
		line = strings.TrimSpace(line)
		match := re.FindStringSubmatch(line)
		if len(match) > 1 {
			packages = append(packages, match[1])
		}
	}

	return Deduplicate(packages), nil
}

// Deduplicate removes duplicate strings from a slice
func Deduplicate(input []string) []string {
	seen := make(map[string]struct{})
	var result []string
	for _, item := range input {
		if _, ok := seen[item]; !ok {
			seen[item] = struct{}{}
			result = append(result, item)
		}
	}
	return result
}