package pwgenerator

import (
	"strings"

	"r00t2.io/goutils/multierr"
)

// Generate generates a list of passwords for a GenOpts.
func (o *GenOpts) Generate() (passwords []string, err error) {

	var passwds []string = make([]string, o.Count)
	var charset CharSet = o.Chars()
	var errs *multierr.MultiError = multierr.NewMultiError(nil)

	if o.Count == 0 {
		o.Count = DefCount
	}
	if o.LengthMax == 0 {
		o.LengthMax = DefMaxLen
	}

	for idx, _ := range passwds {
		if passwds[idx], err = o.generatePassword(charset); err != nil {
			errs.AddError(err)
			err = nil
		}
	}

	passwords = passwds

	if !errs.IsEmpty() {
		err = errs
	}

	return
}

// generatePassword generates a single password from CharSet c.
func (o *GenOpts) generatePassword(c CharSet) (password string, err error) {

	var maxMin uint
	var trueMinLen uint
	var passLenGap uint
	var passLen int
	var passAlloc []rune

	// Sanity checks/error conditions.
	maxMin = o.CountUpper + o.CountLower + o.CountSymbols + o.CountExtended
	if maxMin > o.LengthMax {
		err = ErrTooSmall
		return
	}
	if o.LengthMin > o.LengthMax {
		err = ErrSwitchedLenLimits
		return
	}

	// Defaults.
	trueMinLen = o.LengthMin
	if trueMinLen == 0 {
		trueMinLen = DefMinLin
	}

	// Get a fixed password length...
	passLenGap = o.LengthMax - trueMinLen
	if passLen, err = saferRandInt(int(passLenGap)); err != nil {
		return
	}
	passLen = passLen + int(trueMinLen) // (We need to re-add; it was subtracted above to get a zero-shifted number for start in saferRandInt.)
	// And make the rune slice of that length.
	passAlloc = make([]rune, passLen)

	for _, idx := range passAlloc {
		var char Char

		if char, err = c.RandChar(); err != nil {
			return
		}

		passAlloc[idx] = rune(char)
	}

	password = string(passAlloc)

	return
}

// Chars returns the list of evaluated characters that would be used in a GenOpts.
func (o *GenOpts) Chars() (chars CharSet) {

	chars = make(CharSet, 0)

	if o.explicitCharset != nil && len(o.explicitCharset) != 0 {
		chars = o.explicitCharset
		return
	}

	if o.Alpha {
		chars = append(chars, alpha...)
	}
	if o.Numeric {
		chars = append(chars, numeric...)
	}
	if o.Symbols {
		chars = append(chars, symbols...)
	}
	if o.ExtendedSymbols {
		chars = append(chars, extendedSymbols...)
	}

	// TODO: Count* fields

	return
}

/*
	SetExplicitCharset sets a GenOpts' charset to an explicit selection. It is deduplicated before being used unless inclDupes is true.
	(Duplicate runes can be used to increase the likelihood of specific characters.)

	Note that if an explicit charset is defined, the following opts will have NO effect:

			Alpha
			Numeric
			Symbols
			ExtendedSymbols
			CountUpper
			CountLower
			CountSymbols
			CountExtended
			DisabledChars

	To have these fields be used again, call GenOpts.UnsetExplicitCharset.

	chars can be a CharSet, []rune, []byte, []string, or string
*/
func (o *GenOpts) SetExplicitCharset(chars interface{}, inclDupes bool) (err error) {

	var charset CharSet

	switch t := chars.(type) {
	case []rune:
		charset = CharSet(string(t))
	case []byte:
		charset = CharSet(string(t))
	case []string:
		s := strings.Join(t, "")
		charset = CharSet(s)
	case string:
		charset = CharSet(t)
	default:
		err = ErrBadType
		return
	}

	if !inclDupes {
		sortDedupe(&charset)
	}

	o.explicitCharset = charset

	return
}

/*
	UnsetExplicitCharset removes the explicit charset used for generation and instead uses the fields specified in the actual GenOpts.

	See GenOpts.SetExplicitCharset for more details.
*/
func (o *GenOpts) UnsetExplicitCharset() {

	o.explicitCharset = nil

	return
}