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70 lines
2.3 KiB
Go
70 lines
2.3 KiB
Go
// Package random contains helpers to aid with randomness
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package random
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import (
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"crypto/md5" // #nosec G501 // Unly used to convert a string into a numer, no need for cryptographic safety
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"fmt"
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"math"
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"math/rand"
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"github.com/pkg/errors"
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"github.com/Luzifer/twitch-bot/v3/plugins"
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)
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// Register provides the plugins.RegisterFunc
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func Register(args plugins.RegistrationArguments) error {
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args.RegisterTemplateFunction("randomString", plugins.GenericTemplateFunctionGetter(randomString), plugins.TemplateFuncDocumentation{
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Description: "Randomly picks a string from a list of strings",
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Syntax: "randomString <string> [...string]",
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Example: &plugins.TemplateFuncDocumentationExample{
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Template: `{{ randomString "a" "b" "c" "d" }}`,
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FakedOutput: "a",
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},
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})
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args.RegisterTemplateFunction("seededRandom", plugins.GenericTemplateFunctionGetter(stableRandomFromSeed), plugins.TemplateFuncDocumentation{
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Description: "Returns a float value stable for the given seed",
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Syntax: "seededRandom <string-seed>",
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Example: &plugins.TemplateFuncDocumentationExample{
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Template: `Your int this hour: {{ printf "%.0f" (mulf (seededRandom (list "int" .username (now | date "2006-01-02 15") | join ":")) 100) }}%`,
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},
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})
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return nil
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}
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func randomString(lst ...string) (string, error) {
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if len(lst) == 0 {
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return "", errors.New("empty list given")
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}
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return lst[rand.Intn(len(lst))], nil // #nosec:G404 // This is used to select a random string from a list, no crypto-use
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}
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func stableRandomFromSeed(seed string) (float64, error) {
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seedValue, err := stringToSeed(seed)
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if err != nil {
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return 0, errors.Wrap(err, "generating seed")
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}
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return rand.New(rand.NewSource(seedValue)).Float64(), nil // #nosec:G404 // Only used for generating a random number from static string, no need for cryptographic safety
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}
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func stringToSeed(s string) (int64, error) {
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hash := md5.New() // #nosec:G401 // Unly used to convert a string into a numer, no need for cryptographic safety
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if _, err := fmt.Fprint(hash, s); err != nil {
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return 0, errors.Wrap(err, "writing string to hasher")
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}
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var (
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hashSum = hash.Sum(nil)
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sum int64
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)
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for i := 0; i < len(hashSum); i++ {
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sum += int64(float64(hashSum[len(hashSum)-1-i]%10) * math.Pow(10, float64(i))) //nolint:gomnd // No need to put the 10 of 10**i into a constant named "ten"
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}
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return sum, nil
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}
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