package main

import (
	"flag"
	"fmt"
	"log"
	"os"
)

// Constants
const DefaultMinLenght int = 12
const DefaultMaxLenght int = 20
const VersionString string = "0.3.2"

type Config struct {
	minPassLen    int
	maxPassLen    int
	numOfPass     int
	useComplex    bool
	useLowerCase  bool
	useUpperCase  bool
	useNumber     bool
	useSpecial    bool
	humanReadable bool
	checkHibp     bool
	excludeChars  string
	newStyleModes string
	spellPassword bool
	ShowHelp      bool
	showVersion   bool
	outputMode    int
}

// Help text
const usage = `apg-go // A "Automated Password Generator"-clone
Copyright (c) 2021 Winni Neessen

apg [-m <length>] [-x <length>] [-L] [-U] [-N] [-S] [-H] [-C]
    [-l] [-M mode] [-E char_string] [-n num_of_pass] [-v] [-h]

Options:
    -m LENGTH            Minimum length of the password to be generated (Default: 12)
    -x LENGTH            Maximum length of the password to be generated (Default: 20)
    -n NUMBER            Amount of password to be generated (Default: 6)
    -E CHARS             List of characters to be excluded in the generated password
    -M [LUNSHClunshc]    New style password parameters (upper case: on, lower case: off)
    -L                   Use lower case characters in passwords (Default: on)
    -U                   Use upper case characters in passwords (Default: on)
    -N                   Use numeric characters in passwords (Default: on)
    -S                   Use special characters in passwords (Default: off)
    -H                   Avoid ambiguous characters in passwords (i. e.: 1, l, I, O, 0) (Default: off)
    -C                   Enable complex password mode (implies -L -U -N -S and disables -H) (Default: off)
    -l                   Spell generated passwords in phonetic alphabet (Default: off)
    -p                   Check the HIBP database if the generated passwords was found in a leak before (Default: off)
                         '--> this feature requires internet connectivity 
    -h                   Show this help text
    -v                   Show version string`

// Main function that generated the passwords and returns them
func main() {
	// Log config
	log.SetFlags(log.Ltime | log.Ldate | log.Lshortfile)

	// Read and parse flags
	flag.Usage = func() { _, _ = fmt.Fprintf(os.Stderr, "%s\n", usage) }
	var config = parseFlags()

	// Show version and exit
	if config.showVersion {
		_, _ = os.Stderr.WriteString(`apg-go // A "Automated Password Generator"-clone v` + VersionString + "\n")
		_, _ = os.Stderr.WriteString("(C) 2021 by Winni Neessen\n")
		os.Exit(0)
	}

	// Set PW length and available characterset
	charRange := getCharRange(&config)

	// Generate passwords
	for i := 1; i <= config.numOfPass; i++ {
		pwLength := getPwLengthFromParams(&config)
		pwString, err := getRandChar(&charRange, pwLength)
		if err != nil {
			log.Fatalf("getRandChar returned an error: %q\n", err)
		}

		switch config.outputMode {
		case 1:
			{
				spelledPw, err := spellPasswordString(pwString)
				if err != nil {
					log.Fatalf("spellPasswordString returned an error: %q\n", err.Error())
				}
				fmt.Printf("%v (%v)\n", pwString, spelledPw)
				break
			}
		default:
			{
				fmt.Println(pwString)
				break
			}
		}

		if config.checkHibp {
			isPwned, err := checkHibp(pwString)
			if err != nil {
				log.Printf("unable to check HIBP database: %v", err)
			}
			if isPwned {
				fmt.Print("^-- !!WARNING: The previously generated password was found in HIPB database. Do not use it!!\n")
			}
		}
	}
}