go-caatsm/internal/parsers/pattern.go

package parsers

import (
	"regexp"
)

type BodyConfig struct {
	Patterns []PatternConfig
}

type PatternConfig struct {
	Pattern    string
	Comments   string
	Expression *regexp.Regexp
}

const (
	arrPatternString = `^\((?P<category>[A-Z]{3})` +
		`-(?P<number>[A-Z0-9]+)(\/?(?P<ssr>[A-Z0-9]+))?` +
		`-(?P<dep>[A-Z]{4})` +
		`-(?P<arr>[A-Z]{4})(?P<arr_time>\d{4})\)$`

	// depPatternString represents the regular expression pattern used to match departure patterns.
	// The pattern matches strings in the format: "(TYPE-NUMBER-SSR-DEPARTURE-DEPARTURE_TIME-ARRIVAL)".
	// The pattern captures the following named groups:
	// - category: the three-letter category code
	// - number: the alphanumeric flight number
	// - ssr: the alphanumeric SSR code
	// - departure: the four-letter departure airport code
	// - departure_time: the four-digit departure time
	// - arrival: the four-letter arrival airport code
	depPatternString = `^\((?P<category>[A-Z]{3})-(?P<number>[A-Z0-9]+)(\/(?P<ssr>[A-Z0-9]+))?-(?P<dep>[A-Z]{4})(?P<dep_time>\d{4})-(?P<arr>[A-Z]{4})\)$`

	// fplPatternString represents the regular expression pattern used to match flight plan patterns.
	// The pattern matches strings in the format: "(CATEGORY-NUMBER-INDICATOR-AIRCRAFT-SURVE-DEPARTURE-DEPARTURE_TIME-SPEED-LEVEL-ROUTE-DESTINATION-ESTT-ALTER-OTHER)".
	// The pattern captures the following named groups:
	// - category: the three-letter category code
	// - number: the alphanumeric flight number
	// - indicator: the two-letter indicator
	// - aircraft: the alphanumeric aircraft type, optionally followed by a slash and an uppercase letter
	// - surve: any character sequence (surveillance information)
	// - departure: the four-letter departure airport code
	// - departure_time: the four-digit departure time
	// - speed: one or more uppercase letters followed by one or more digits (e.g., N123)
	// - level: one or more alphanumeric characters (e.g., FL350)
	// - route: one or more characters (including newline) representing the flight route
	// - destination: the four-letter destination airport code
	// - estt: the four-digit estimated time of arrival
	// - alter: one or more sequences of a whitespace character followed by exactly four uppercase letters
	// - other: any other relevant information, starting with three uppercase letters followed by a forward slash and zero or more characters (including newline)

	fplPatternString = `\((?P<category>[A-Z]{3})-(?P<number>[A-Z]+\d+)-(?P<indicator>[A-Z]{2})\n-(?P<aircraft>[A-Z]+\d+\/?[A-Z]?)\n?-(?P<surve>.*)\n?-(?P<dep>[A-Z]{4})(?P<dep_time>\d{4})\n?-(?P<speed>[A-Z]+\d+)(?P<level>[A-Z0-9]+)\s+(?P<route>(.|\n)+)\n-(?P<dest>[A-Z]{4})(?P<estt>\d{4})\s?(?P<alter>(\s[A-Z]{4})+)\n?-([A-Z]{3}\/(?:[A-Z]{4}\d{4}\s?)+)?(?P<other>(?m)[A-Z]{3}\/(.|\n)*)\)$`

	cnlPatternString = `^\((?P<category>[A-Z]{3})-(?P<number>\w+\d+)-?(?P<dep>[A-Z]{4})?-?(?<arr>[A-Z]{4})\)$`

	dlaPatternString = `^\((?P<category>[A-Z]{3})-(?P<number>\w+\d+)-?(?P<dep>[A-Z]{4})(?P<dep_time>\d{4})?-?(?<arr>[A-Z]{4})(?<arr_time>\d{4})?\)$`
)

var (
	bodyTypePattern = regexp.MustCompile(`^\(([A-Z]{3})(.*\n?)+\)$`)

	bodyPatterns = map[string]BodyConfig{
		"ARR": {
			Patterns: []PatternConfig{
				{
					Pattern:    arrPatternString,
					Comments:   "Pattern for ARR message",
					Expression: regexp.MustCompile(arrPatternString),
				},
			},
		},
		"DEP": {
			Patterns: []PatternConfig{
				{
					Pattern:    depPatternString,
					Comments:   "Pattern for DEP message",
					Expression: regexp.MustCompile(depPatternString),
				},
			},
		},
		"FPL": {
			Patterns: []PatternConfig{
				{
					Pattern:    fplPatternString,
					Comments:   "Pattern for FPL message",
					Expression: regexp.MustCompile(fplPatternString),
				},
			},
		},
		"CNL": {
			Patterns: []PatternConfig{
				{
					Pattern:    cnlPatternString,
					Comments:   "Pattern for CNL message",
					Expression: regexp.MustCompile(cnlPatternString),
				},
			},
		},
		"DLA": {
			Patterns: []PatternConfig{
				{
					Pattern:    dlaPatternString,
					Comments:   "Pattern for DLA message",
					Expression: regexp.MustCompile(dlaPatternString),
				},
			},
		},
	}
)

func FindPatterns(messageBody string) *BodyConfig {
	if match := bodyTypePattern.FindStringSubmatch(messageBody); len(match) > 1 {
		name := match[1]
		patters := bodyPatterns
		if bodyConfig, found := patters[name]; found {
			return &bodyConfig
		}
	}
	return nil
}

func ParseBody(messageBody string) map[string]string {
	if body := FindPatterns(messageBody); body != nil {
		for _, pattern := range body.Patterns {
			if matches := pattern.Expression.FindStringSubmatch(messageBody); matches != nil {
				result := make(map[string]string)
				for i, name := range pattern.Expression.SubexpNames() {
					if i != 0 && name != "" {
						result[name] = matches[i]
					}
				}
				return result
			}
		}
	}
	return nil
}