package lagoon

import (
	"encoding/csv"
	"encoding/json"
	"fmt"
	"io"
	"math"
	"math/big"
	"net"
	"net/http"
	"reflect"
	"regexp"
	"slices"
	"strconv"
	"strings"
	"time"
	"unicode/utf8"
)

// implicitRuleNames run even when the attribute is absent or blank, and a
// failure of one stops the attribute (Laravel's implicitRules).
var implicitRuleNames = []string{"required", "present", "filled", "accepted"}

// numericRuleNames make the size rules compare the value as a number.
var numericRuleNames = []string{"numeric", "integer"}

var sizeRuleNames = map[string]bool{"size": true, "between": true, "min": true, "max": true}

// imageExtensions is Laravel's image rule: mimes:jpg,jpeg,png,gif,bmp,svg,webp.
var imageExtensions = []string{"jpg", "jpeg", "png", "gif", "bmp", "svg", "webp"}

// requestRuleArity lists every rule ValidateRequest implements with its
// parameter count: -1 any number (at least one), 0 none.
var requestRuleArity = map[string]int{
	"required": 0, "present": 0, "filled": 0, "accepted": 0,
	"nullable": 0, "sometimes": 0, "bail": 0,
	"array": -2, "string": 0, "integer": 0, "numeric": 0, "boolean": 0,
	"email": 0, "url": 0, "date": 0,
	"after": 1, "after_or_equal": 1, "before": 1, "before_or_equal": 1,
	"exists": -1, "regex": 1, "not_regex": 1,
	"in": -1, "not_in": -1, "mimes": -1, "image": 0, "file": 0,
	"min": 1, "max": 1, "size": 1, "between": 2,
}

func isImplicitName(name string) bool {
	for _, n := range implicitRuleNames {
		if n == name {
			return true
		}
	}
	return false
}

func (r Rule) isImplicit() bool {
	return r.custom == nil && isImplicitName(r.name)
}

type compiledRegex struct {
	re *regexp.Regexp
}

// ParseRules parses a Laravel rule string such as "required|string|max:255"
// into rules. Parameters are split like PHP's str_getcsv (`in:LP,"EP 7"""`);
// a regex: or not_regex: parameter is kept whole, pipes and commas included,
// up to its closing PCRE delimiter. ParseRules is meant for rule tables built
// at package initialization: an unknown rule, a wrong parameter count, an
// unsafe exists: identifier or a pattern Go's RE2 cannot compile panics, so a
// broken table fails at boot and never at request time.
func ParseRules(spec string) []Rule {
	var out []Rule
	for _, tok := range splitRuleSpec(spec) {
		out = append(out, mustParseRule(tok))
	}
	return out
}

func splitRuleSpec(spec string) []string {
	var out []string
	rest := spec
	for rest != "" {
		trimmed := strings.TrimLeft(rest, " \t")
		if strings.HasPrefix(trimmed, "regex:") || strings.HasPrefix(trimmed, "not_regex:") {
			name, pat, _ := strings.Cut(trimmed, ":")
			end := regexTokenEnd(pat)
			out = append(out, name+":"+pat[:end])
			rest = pat[end:]
			rest = strings.TrimPrefix(rest, "|")
			continue
		}
		tok, after, found := strings.Cut(rest, "|")
		if t := strings.TrimSpace(tok); t != "" {
			out = append(out, t)
		}
		if !found {
			break
		}
		rest = after
	}
	return out
}

// regexTokenEnd finds where a PCRE literal ends inside a rule string: at the
// first unescaped closing delimiter that is followed by modifiers and then a
// pipe or the end of the string.
func regexTokenEnd(pat string) int {
	if pat == "" {
		return 0
	}
	open, size := utf8.DecodeRuneInString(pat)
	closing := closingDelimiter(open)
	for i := size; i < len(pat); i++ {
		c := pat[i]
		if c == '\\' {
			i++
			continue
		}
		if rune(c) != closing {
			continue
		}
		j := i + 1
		for j < len(pat) && isPCREModifier(pat[j]) {
			j++
		}
		if j == len(pat) || pat[j] == '|' {
			return j
		}
	}
	if k := strings.Index(pat, "|"); k >= 0 {
		return k
	}
	return len(pat)
}

func closingDelimiter(open rune) rune {
	switch open {
	case '(':
		return ')'
	case '[':
		return ']'
	case '{':
		return '}'
	case '<':
		return '>'
	}
	return open
}

func isPCREModifier(c byte) bool {
	return strings.IndexByte("imsxuADSUXJn", c) >= 0
}

func mustParseRule(tok string) Rule {
	name, param, hasParam := strings.Cut(tok, ":")
	name = strings.ToLower(strings.TrimSpace(name))
	switch name {
	case "int":
		name = "integer"
	case "bool":
		name = "boolean"
	}
	arity, known := requestRuleArity[name]
	if !known {
		panic(fmt.Sprintf("lagoon: ParseRules: unsupported rule %q", tok))
	}
	var args []string
	if hasParam {
		if name == "regex" || name == "not_regex" {
			args = []string{param}
		} else {
			args = phpGetCSV(param)
		}
	}
	switch {
	case arity == 0 && len(args) > 0:
		panic(fmt.Sprintf("lagoon: ParseRules: rule %q takes no parameters", tok))
	case arity > 0 && len(args) != arity:
		panic(fmt.Sprintf("lagoon: ParseRules: rule %q needs %d parameter(s)", tok, arity))
	case arity == -1 && len(args) == 0:
		panic(fmt.Sprintf("lagoon: ParseRules: rule %q needs parameters", tok))
	}
	r := Rule{name: name, args: args}
	switch name {
	case "min", "max", "size", "between":
		for _, a := range args {
			if _, ok := new(big.Rat).SetString(strings.TrimSpace(a)); !ok {
				panic(fmt.Sprintf("lagoon: ParseRules: rule %q has a non-numeric parameter", tok))
			}
		}
	case "regex", "not_regex":
		re, err := compilePCRE(args[0])
		if err != nil {
			panic(fmt.Sprintf("lagoon: ParseRules: rule %q: %v", tok, err))
		}
		r.re = &compiledRegex{re: re}
	case "exists":
		if len(args) > 2 {
			panic(fmt.Sprintf("lagoon: ParseRules: rule %q: extra where clauses are not supported", tok))
		}
		table := args[0]
		if i := strings.LastIndex(table, "."); i >= 0 {
			table = table[i+1:]
		}
		if !identName.MatchString(table) {
			panic(fmt.Sprintf("lagoon: ParseRules: rule %q: unsafe table name", tok))
		}
		r.args[0] = table
		if len(args) == 2 && args[1] != "NULL" && !identName.MatchString(args[1]) {
			panic(fmt.Sprintf("lagoon: ParseRules: rule %q: unsafe column name", tok))
		}
	}
	return r
}

// phpGetCSV splits a rule parameter list like PHP's str_getcsv: commas
// separate fields, a field may be double-quoted with "" as an escaped quote,
// and a quote inside an unquoted field is kept.
func phpGetCSV(s string) []string {
	r := csv.NewReader(strings.NewReader(s))
	r.LazyQuotes = true
	r.FieldsPerRecord = -1
	rec, err := r.Read()
	if err != nil {
		return []string{s}
	}
	return rec
}

// compilePCRE turns a PCRE literal (/pattern/flags) into a Go regexp. The i,
// m, s, u and D modifiers are supported (u is implied, D is Go's default end
// anchoring); any other modifier is an error.
func compilePCRE(lit string) (*regexp.Regexp, error) {
	if len(lit) < 2 {
		return nil, fmt.Errorf("pattern %q has no delimiters", lit)
	}
	open, size := utf8.DecodeRuneInString(lit)
	if open == '\\' || open == utf8.RuneError || (open < 128 && (isAlnumByte(byte(open)) || open == ' ')) {
		return nil, fmt.Errorf("pattern %q has an invalid delimiter", lit)
	}
	closing := closingDelimiter(open)
	end := strings.LastIndex(lit, string(closing))
	if end < size {
		return nil, fmt.Errorf("pattern %q has no closing delimiter", lit)
	}
	body := lit[size:end]
	flags := ""
	for _, m := range lit[end+1:] {
		switch m {
		case 'i', 'm', 's':
			if !strings.ContainsRune(flags, m) {
				flags += string(m)
			}
		case 'u', 'D':
		default:
			return nil, fmt.Errorf("pattern %q uses the unsupported modifier %q", lit, m)
		}
	}
	if open == closing {
		body = strings.ReplaceAll(body, `\`+string(open), string(open))
	}
	if flags != "" {
		body = "(?" + flags + ")" + body
	}
	return regexp.Compile(body)
}

func isAlnumByte(c byte) bool {
	return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9')
}

func (v *requestValidator) passes(rule Rule, attr string, value any, present bool) (bool, error) {
	switch rule.name {
	case "required":
		return validateRequired(value), nil
	case "present":
		return present, nil
	case "filled":
		return !present || validateRequired(value), nil
	case "accepted":
		return validateRequired(value) && isAccepted(value), nil
	case "nullable", "sometimes", "bail":
		return true, nil
	case "array":
		return validateArray(value, rule.args), nil
	case "string":
		_, ok := value.(string)
		return ok, nil
	case "integer":
		return filterInt(value), nil
	case "numeric":
		return isNumeric(value), nil
	case "boolean":
		return isStrictBoolean(value), nil
	case "email":
		s, ok := value.(string)
		return ok && filterEmail(s), nil
	case "url":
		s, ok := value.(string)
		return ok && urlPattern.MatchString(s), nil
	case "date":
		return validateDate(value), nil
	case "after":
		return v.compareDates(value, rule.args[0], ">"), nil
	case "after_or_equal":
		return v.compareDates(value, rule.args[0], ">="), nil
	case "before":
		return v.compareDates(value, rule.args[0], "<"), nil
	case "before_or_equal":
		return v.compareDates(value, rule.args[0], "<="), nil
	case "exists":
		return v.exists(attr, rule, value)
	case "regex", "not_regex":
		s, ok := regexSubject(value)
		if !ok {
			return false, nil
		}
		matched := rule.re.re.MatchString(s)
		if rule.name == "regex" {
			return matched, nil
		}
		return !matched, nil
	case "in":
		return v.validateIn(attr, value, rule.args), nil
	case "not_in":
		return v.validateNotIn(attr, value, rule.args), nil
	case "file":
		_, ok := asUploadedFile(value)
		return ok, nil
	case "image":
		return validateMimes(value, imageExtensions), nil
	case "mimes":
		return validateMimes(value, rule.args), nil
	case "min", "max", "size", "between":
		size, ok := v.size(attr, value)
		if !ok {
			return false, nil
		}
		return sizeInRange(rule, size), nil
	}
	return false, fmt.Errorf("lagoon: rule %q is not implemented", rule.name)
}

func sizeInRange(rule Rule, size *big.Rat) bool {
	bound := func(i int) *big.Rat {
		r, _ := new(big.Rat).SetString(strings.TrimSpace(rule.args[i]))
		return r
	}
	switch rule.name {
	case "min":
		return size.Cmp(bound(0)) >= 0
	case "max":
		return size.Cmp(bound(0)) <= 0
	case "size":
		return size.Cmp(bound(0)) == 0
	default: // between
		return size.Cmp(bound(0)) >= 0 && size.Cmp(bound(1)) <= 0
	}
}

// size is Laravel's getSize: the number itself under a numeric rule, the
// element count of an array, kilobytes of a file, else the length of the
// string form in characters (PHP mb_strlen).
func (v *requestValidator) size(attr string, value any) (*big.Rat, bool) {
	if isNumeric(value) && v.hasRule(attr, numericRuleNames...) {
		s, _ := phpScalarString(value)
		r, ok := new(big.Rat).SetString(phpTrim(s))
		return r, ok
	}
	if n, ok := arrayLen(value); ok {
		return new(big.Rat).SetInt64(int64(n)), true
	}
	if f, ok := asUploadedFile(value); ok {
		return new(big.Rat).SetFrac64(f.Size, 1024), true
	}
	if value == nil {
		return new(big.Rat), true
	}
	s, ok := phpScalarString(value)
	if !ok {
		return nil, false
	}
	return new(big.Rat).SetInt64(int64(utf8.RuneCountInString(s))), true
}

func validateRequired(value any) bool {
	switch t := value.(type) {
	case nil:
		return false
	case string:
		return phpTrim(t) != ""
	}
	if n, ok := arrayLen(value); ok {
		return n > 0
	}
	if f, ok := asUploadedFile(value); ok {
		return f.Filename != "" || f.Size > 0
	}
	return true
}

func isAccepted(value any) bool {
	switch t := value.(type) {
	case bool:
		return t
	case string:
		return t == "yes" || t == "on" || t == "1" || t == "true"
	case json.Number:
		return string(t) == "1"
	case float64:
		return t == 1
	case int:
		return t == 1
	case int64:
		return t == 1
	}
	return false
}

func validateArray(value any, keys []string) bool {
	if _, ok := arrayLen(value); !ok {
		return false
	}
	if len(keys) == 0 {
		return true
	}
	allowed := map[string]bool{}
	for _, k := range keys {
		allowed[k] = true
	}
	for _, ch := range children(value) {
		if !allowed[ch.key] {
			return false
		}
	}
	return true
}

func arrayLen(value any) (int, bool) {
	switch t := value.(type) {
	case []any:
		return len(t), true
	case map[string]any:
		return len(t), true
	case []string:
		return len(t), true
	case []map[string]any:
		return len(t), true
	}
	rv := reflect.ValueOf(value)
	if rv.Kind() == reflect.Slice || rv.Kind() == reflect.Map {
		return rv.Len(), true
	}
	return 0, false
}

func isStrictBoolean(value any) bool {
	switch t := value.(type) {
	case bool:
		return true
	case string:
		return t == "0" || t == "1"
	case json.Number:
		return string(t) == "0" || string(t) == "1"
	case float64:
		return t == 0 || t == 1
	case int:
		return t == 0 || t == 1
	case int64:
		return t == 0 || t == 1
	}
	return false
}

// isNumeric ports PHP's is_numeric: numbers, and strings holding a decimal
// or exponent number with optional surrounding whitespace.
func isNumeric(value any) bool {
	switch t := value.(type) {
	case string:
		return isNumericString(t)
	case json.Number:
		return isNumericString(string(t))
	case float32:
		return true
	case float64:
		return true
	case int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64:
		return true
	}
	return false
}

func isNumericString(s string) bool {
	s = strings.TrimLeft(s, " \t\n\r\v\f")
	s = strings.TrimRight(s, " \t\n\r\v\f")
	if s == "" {
		return false
	}
	i := 0
	if s[i] == '+' || s[i] == '-' {
		i++
	}
	digits := 0
	for i < len(s) && s[i] >= '0' && s[i] <= '9' {
		i++
		digits++
	}
	if i < len(s) && s[i] == '.' {
		i++
		for i < len(s) && s[i] >= '0' && s[i] <= '9' {
			i++
			digits++
		}
	}
	if digits == 0 {
		return false
	}
	if i < len(s) && (s[i] == 'e' || s[i] == 'E') {
		i++
		if i < len(s) && (s[i] == '+' || s[i] == '-') {
			i++
		}
		exp := 0
		for i < len(s) && s[i] >= '0' && s[i] <= '9' {
			i++
			exp++
		}
		if exp == 0 {
			return false
		}
	}
	return i == len(s)
}

// filterInt ports filter_var($value, FILTER_VALIDATE_INT) !== false: the
// string form, trimmed, must be an optionally signed decimal integer with no
// leading zero that fits in 64 bits. true counts as 1.
func filterInt(value any) bool {
	var s string
	switch t := value.(type) {
	case bool:
		return t
	case nil:
		return false
	case int, int8, int16, int32, int64, uint8, uint16, uint32:
		return true
	case uint:
		return uint64(t) <= math.MaxInt64
	case uint64:
		return t <= math.MaxInt64
	case string:
		s = t
	case json.Number:
		s = string(t)
		if f, err := strconv.ParseFloat(s, 64); err == nil && strings.ContainsAny(s, ".eE") {
			s = phpFloatString(f)
		}
	case float32:
		s = phpFloatString(float64(t))
	case float64:
		s = phpFloatString(t)
	default:
		return false
	}
	s = strings.Trim(s, " \t\r\n\v\x00")
	if s == "" {
		return false
	}
	body := s
	if body[0] == '+' || body[0] == '-' {
		body = body[1:]
	}
	if body == "" {
		return false
	}
	for i := 0; i < len(body); i++ {
		if body[i] < '0' || body[i] > '9' {
			return false
		}
	}
	if len(body) > 1 && body[0] == '0' {
		return false
	}
	_, err := strconv.ParseInt(s, 10, 64)
	return err == nil
}

// phpScalarString is PHP's (string) cast for scalars.
func phpScalarString(value any) (string, bool) {
	switch t := value.(type) {
	case nil:
		return "", true
	case string:
		return t, true
	case json.Number:
		if _, err := strconv.ParseInt(string(t), 10, 64); err == nil {
			return string(t), true
		}
		if f, err := strconv.ParseFloat(string(t), 64); err == nil {
			return phpFloatString(f), true
		}
		return string(t), true
	case bool:
		if t {
			return "1", true
		}
		return "", true
	case float32:
		return phpFloatString(float64(t)), true
	case float64:
		return phpFloatString(t), true
	case int:
		return strconv.Itoa(t), true
	case int8, int16, int32, int64:
		return strconv.FormatInt(reflect.ValueOf(t).Int(), 10), true
	case uint, uint8, uint16, uint32, uint64:
		return strconv.FormatUint(reflect.ValueOf(t).Uint(), 10), true
	}
	return "", false
}

// phpFloatString formats a float as PHP 8 casts it to string: %.14G with
// the default precision ini of 14 (zend_gcvt). The value is correctly
// rounded to 14 significant digits and trailing zeros are dropped; it is
// written in exponent form (1.0E+15, 1.5E-5) when the decimal point would
// sit more than 14 digits right or more than 3 zeros left of the digits.
func phpFloatString(f float64) string {
	switch {
	case math.IsNaN(f):
		return "NAN"
	case math.IsInf(f, 1):
		return "INF"
	case math.IsInf(f, -1):
		return "-INF"
	case f == 0:
		if math.Signbit(f) {
			return "-0"
		}
		return "0"
	}
	const precision = 14
	e := strconv.FormatFloat(math.Abs(f), 'e', precision-1, 64)
	mant, expStr, _ := strings.Cut(e, "e")
	exp, _ := strconv.Atoi(expStr)
	digits := strings.TrimRight(strings.Replace(mant, ".", "", 1), "0")
	if digits == "" {
		digits = "0"
	}
	decpt := exp + 1
	var out string
	switch {
	case decpt < -3 || decpt > precision:
		m := digits[:1] + ".0"
		if len(digits) > 1 {
			m = digits[:1] + "." + digits[1:]
		}
		sign := "+"
		if exp < 0 {
			sign, exp = "-", -exp
		}
		out = m + "E" + sign + strconv.Itoa(exp)
	case decpt <= 0:
		out = "0." + strings.Repeat("0", -decpt) + digits
	case decpt >= len(digits):
		out = digits + strings.Repeat("0", decpt-len(digits))
	default:
		out = digits[:decpt] + "." + digits[decpt:]
	}
	if f < 0 {
		out = "-" + out
	}
	return out
}

// phpTrim trims the characters PHP's trim() does.
func phpTrim(s string) string {
	return strings.Trim(s, " \t\n\r\x00\x0B")
}

func regexSubject(value any) (string, bool) {
	if s, ok := value.(string); ok {
		return s, true
	}
	if isNumeric(value) {
		return phpScalarString(value)
	}
	return "", false
}

func asUploadedFile(value any) (UploadedFile, bool) {
	switch t := value.(type) {
	case UploadedFile:
		return t, true
	case *UploadedFile:
		if t != nil {
			return *t, true
		}
	}
	return UploadedFile{}, false
}

// in compares like PHP's in_array((string) $value, $parameters): two numeric
// strings compare as numbers, anything else as bytes.
func phpLooseStringEqual(a, b string) bool {
	if a == b {
		return true
	}
	if isNumericString(a) && isNumericString(b) {
		ra, ok1 := new(big.Rat).SetString(phpTrim(a))
		rb, ok2 := new(big.Rat).SetString(phpTrim(b))
		return ok1 && ok2 && ra.Cmp(rb) == 0
	}
	return false
}

func inList(s string, list []string) bool {
	for _, p := range list {
		if phpLooseStringEqual(s, p) {
			return true
		}
	}
	return false
}

// validateIn is Laravel's validateIn. An array value needs the array rule
// and no nested element, and then, like count(array_diff($value,
// $parameters)) === 0, every element's string form must equal a parameter
// exactly. A scalar compares like in_array((string) $value, $parameters),
// where two numeric strings compare as numbers.
func (v *requestValidator) validateIn(attr string, value any, params []string) bool {
	if _, isArr := arrayLen(value); isArr {
		if !v.hasRule(attr, "array") {
			return false
		}
		for _, ch := range children(value) {
			if _, nested := arrayLen(ch.value); nested {
				return false
			}
		}
		for _, ch := range children(value) {
			s, ok := phpScalarString(ch.value)
			if !ok || !slices.Contains(params, s) {
				return false
			}
		}
		return true
	}
	s, ok := phpScalarString(value)
	return ok && inList(s, params)
}

// validateNotIn is Laravel's validateNotIn: the negation of validateIn, so
// an array passes unless every element is listed, and an array without the
// array rule always passes.
func (v *requestValidator) validateNotIn(attr string, value any, params []string) bool {
	return !v.validateIn(attr, value, params)
}

// exists is Laravel's exists:table,column presence check. It counts rows
// whose column, compared as text, equals the value (or, for an array, every
// distinct value); Laravel adds no deleted_at condition and neither does this.
func (v *requestValidator) exists(attr string, rule Rule, value any) (bool, error) {
	if v.tx == nil {
		return false, fmt.Errorf("lagoon: exists:%s requires a database handle", rule.args[0])
	}
	table := rule.args[0]
	column := attr
	if len(rule.args) == 2 && rule.args[1] != "NULL" {
		column = rule.args[1]
	} else if _, expanded := v.primary[attr]; expanded {
		segs := strings.Split(attr, ".")
		if last := segs[len(segs)-1]; !isNumericString(last) {
			column = last
		}
	}
	if !identName.MatchString(table) || !identName.MatchString(column) {
		return false, fmt.Errorf("lagoon: exists identifier %q.%q is not safe", table, column)
	}
	db := v.tx.WithContext(v.ctx)
	if _, isArr := arrayLen(value); isArr {
		uniq := map[string]bool{}
		var vals []string
		for _, ch := range children(value) {
			s, ok := phpScalarString(ch.value)
			if !ok {
				return false, nil
			}
			if !uniq[s] {
				uniq[s] = true
				vals = append(vals, s)
			}
		}
		if len(vals) == 0 {
			return true, nil
		}
		var n int64
		err := db.Table(table).Where("CAST("+column+" AS TEXT) IN ?", vals).
			Distinct("CAST(" + column + " AS TEXT)").Count(&n).Error
		if err != nil {
			return false, err
		}
		return n >= int64(len(vals)), nil
	}
	s, ok := phpScalarString(value)
	if !ok {
		return false, nil
	}
	var n int64
	if err := db.Table(table).Where("CAST("+column+" AS TEXT) = ?", s).Count(&n).Error; err != nil {
		return false, err
	}
	return n >= 1, nil
}

// validateMimes sniffs the uploaded content (http.DetectContentType, plus
// SVG detection) and maps the type to an extension the way Symfony's
// guessExtension does; jpg and jpeg stand for each other, and a client file
// name ending in a PHP extension is refused unless php is allowed.
func validateMimes(value any, allowed []string) bool {
	f, ok := asUploadedFile(value)
	if !ok || f.Open == nil {
		return false
	}
	params := make([]string, 0, len(allowed)+2)
	hasJPEG, hasPHP := false, false
	for _, a := range allowed {
		a = strings.ToLower(strings.TrimSpace(a))
		params = append(params, a)
		hasJPEG = hasJPEG || a == "jpg" || a == "jpeg"
		hasPHP = hasPHP || a == "php"
	}
	if hasJPEG {
		params = append(params, "jpg", "jpeg")
	}
	if !hasPHP {
		ext := strings.ToLower(strings.TrimSpace(fileExtension(f.Filename)))
		switch ext {
		case "php", "php3", "php4", "php5", "php7", "php8", "phtml", "phar":
			return false
		}
	}
	guessed := guessExtension(f)
	if guessed == "" {
		return false
	}
	for _, p := range params {
		if p == guessed {
			return true
		}
	}
	return false
}

func fileExtension(name string) string {
	if i := strings.LastIndex(name, "."); i >= 0 {
		return name[i+1:]
	}
	return ""
}

var mimeExtensions = map[string]string{
	"image/jpeg":                   "jpg",
	"image/png":                    "png",
	"image/gif":                    "gif",
	"image/webp":                   "webp",
	"image/bmp":                    "bmp",
	"image/x-ms-bmp":               "bmp",
	"image/svg+xml":                "svg",
	"image/x-icon":                 "ico",
	"image/vnd.microsoft.icon":     "ico",
	"image/avif":                   "avif",
	"application/pdf":              "pdf",
	"application/zip":              "zip",
	"application/x-gzip":           "gz",
	"application/x-rar-compressed": "rar",
	"application/ogg":              "ogx",
	"application/wasm":             "wasm",
	"application/octet-stream":     "bin",
	"application/json":             "json",
	"text/plain":                   "txt",
	"text/html":                    "html",
	"text/xml":                     "xml",
	"text/css":                     "css",
	"audio/mpeg":                   "mp3",
	"audio/wave":                   "wav",
	"audio/aiff":                   "aif",
	"video/mp4":                    "mp4",
	"video/webm":                   "webm",
	"video/avi":                    "avi",
	"font/woff":                    "woff",
	"font/woff2":                   "woff2",
	"font/ttf":                     "ttf",
	"font/otf":                     "otf",
}

func guessExtension(f UploadedFile) string {
	rc, err := f.Open()
	if err != nil {
		return ""
	}
	defer rc.Close()
	head := make([]byte, 512)
	n, err := io.ReadFull(rc, head)
	if err != nil && err != io.ErrUnexpectedEOF && err != io.EOF {
		return ""
	}
	head = head[:n]
	if n == 0 {
		return ""
	}
	mime, _, _ := strings.Cut(http.DetectContentType(head), ";")
	mime = strings.TrimSpace(mime)
	if strings.HasPrefix(mime, "text/") && looksLikeSVG(head) {
		mime = "image/svg+xml"
	}
	return mimeExtensions[mime]
}

func looksLikeSVG(head []byte) bool {
	s := strings.ToLower(string(head))
	return strings.Contains(s, "<svg")
}

// validateDate ports Laravel's date rule (strtotime then checkdate) for the
// date shapes listed in parseDateValue.
func validateDate(value any) bool {
	s, ok := value.(string)
	if !ok {
		return false
	}
	_, ok = parseDateValue(s)
	return ok
}

// compareDates ports Laravel's compareDates without date_format: the
// parameter is a date or relative word, else the name of another field
// whose value is the date. An unparsable side compares as PHP compares null
// with an integer (both as booleans).
func (v *requestValidator) compareDates(value any, param, op string) bool {
	var vs string
	switch t := value.(type) {
	case string:
		vs = t
	default:
		if !isNumeric(value) {
			return false
		}
		vs, _ = phpScalarString(value)
	}
	var second *int64
	if t, ok := parseDateArg(param); ok && t.Unix() != 0 {
		ts := t.Unix()
		second = &ts
	} else if other, present := v.lookup(param); present {
		if os, isStr := other.(string); isStr {
			if t, ok := parseDateArg(os); ok {
				ts := t.Unix()
				second = &ts
			}
		}
	}
	var first *int64
	if t, ok := parseDateArg(vs); ok {
		ts := t.Unix()
		first = &ts
	}
	return phpCompare(first, second, op)
}

func phpCompare(a, b *int64, op string) bool {
	var c int
	switch {
	case a != nil && b != nil:
		switch {
		case *a < *b:
			c = -1
		case *a > *b:
			c = 1
		}
	default:
		ab := a != nil && *a != 0
		bb := b != nil && *b != 0
		switch {
		case !ab && bb:
			c = -1
		case ab && !bb:
			c = 1
		}
	}
	switch op {
	case ">":
		return c > 0
	case ">=":
		return c >= 0
	case "<":
		return c < 0
	default:
		return c <= 0
	}
}

// requestNow is the clock for relative date words; tests replace it.
var requestNow = time.Now

// parseDateArg parses a date rule parameter or value the way Carbon::parse
// does for the shapes parseDateValue accepts, plus the relative words today,
// tomorrow, yesterday and now (midnight or the current time, in UTC).
func parseDateArg(s string) (time.Time, bool) {
	now := requestNow().UTC()
	midnight := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, time.UTC)
	switch strings.ToLower(strings.TrimSpace(s)) {
	case "now":
		return now, true
	case "today", "midnight":
		return midnight, true
	case "tomorrow":
		return midnight.AddDate(0, 0, 1), true
	case "yesterday":
		return midnight.AddDate(0, 0, -1), true
	}
	return parseDateValue(s)
}

var (
	dateISO   = regexp.MustCompile(`^(\d{4})-(\d{1,2})-(\d{1,2})(?:[T ](\d{1,2}):(\d{2})(?::(\d{2})(?:\.(\d{1,9}))?)?)?\s*(Z|[+-]\d{2}(?::?\d{2})?)?$`)
	dateSlash = regexp.MustCompile(`^(\d{4})/(\d{1,2})/(\d{1,2})$`)
	dateUS    = regexp.MustCompile(`^(\d{1,2})/(\d{1,2})/(\d{4})$`)
	dateDot   = regexp.MustCompile(`^(\d{1,2})[.-](\d{1,2})[.-](\d{4})$`)
)

// parseDateValue accepts the date shapes the API clients send, all read in
// UTC unless an offset is given: Y-m-d, Y-m-d H:i[:s[.u]] and the ISO 8601
// form with a T, Z or an offset; Y/m/d; m/d/Y (strtotime's American slash
// order); d.m.Y and d-m-Y. The calendar date must exist (checkdate), so
// 2023-02-30 is refused. Other strtotime inputs are refused.
func parseDateValue(s string) (time.Time, bool) {
	s = strings.TrimSpace(s)
	var y, mo, d, h, mi, sec, nsec int
	loc := time.UTC
	switch {
	case dateISO.MatchString(s):
		m := dateISO.FindStringSubmatch(s)
		y, mo, d = atoi(m[1]), atoi(m[2]), atoi(m[3])
		if m[4] != "" {
			h, mi = atoi(m[4]), atoi(m[5])
		}
		if m[6] != "" {
			sec = atoi(m[6])
		}
		if m[7] != "" {
			frac := (m[7] + "000000000")[:9]
			nsec = atoi(frac)
		}
		if z := m[8]; z != "" && z != "Z" {
			sign := 1
			if z[0] == '-' {
				sign = -1
			}
			digits := strings.ReplaceAll(z[1:], ":", "")
			oh := atoi(digits[:2])
			om := 0
			if len(digits) == 4 {
				om = atoi(digits[2:])
			}
			if oh > 23 || om > 59 {
				return time.Time{}, false
			}
			loc = time.FixedZone("", sign*(oh*3600+om*60))
		}
	case dateSlash.MatchString(s):
		m := dateSlash.FindStringSubmatch(s)
		y, mo, d = atoi(m[1]), atoi(m[2]), atoi(m[3])
	case dateUS.MatchString(s):
		m := dateUS.FindStringSubmatch(s)
		mo, d, y = atoi(m[1]), atoi(m[2]), atoi(m[3])
	case dateDot.MatchString(s):
		m := dateDot.FindStringSubmatch(s)
		d, mo, y = atoi(m[1]), atoi(m[2]), atoi(m[3])
	default:
		return time.Time{}, false
	}
	if !checkDate(y, mo, d) || h > 23 || mi > 59 || sec > 59 {
		return time.Time{}, false
	}
	return time.Date(y, time.Month(mo), d, h, mi, sec, nsec, loc), true
}

func atoi(s string) int {
	n, _ := strconv.Atoi(s)
	return n
}

func checkDate(y, m, d int) bool {
	if y < 1 || y > 32767 || m < 1 || m > 12 || d < 1 {
		return false
	}
	return d <= time.Date(y, time.Month(m)+1, 0, 0, 0, 0, 0, time.UTC).Day()
}

// filterEmail ports PHP's FILTER_VALIDATE_EMAIL, the check Winter's email
// rule uses by default: ASCII only, under 255 characters, a local part of
// dot-separated atoms or quoted strings up to 64 characters, and a domain of
// at least two dot-separated labels whose last starts with a letter (or is
// an xn-- label), or a bracketed IPv4 or IPv6 literal.
func filterEmail(s string) bool {
	if s == "" || len(s) >= 255 {
		return false
	}
	for i := 0; i < len(s); i++ {
		if s[i] >= 0x80 {
			return false
		}
	}
	at := emailLocalEnd(s)
	if at <= 0 || at >= len(s) || s[at] != '@' || at > 64 {
		return false
	}
	return emailDomainOK(s[at+1:])
}

func isAtext(c byte) bool {
	switch {
	case c >= 'a' && c <= 'z', c >= 'A' && c <= 'Z', c >= '0' && c <= '9':
		return true
	}
	return strings.IndexByte("!#$%&'*+-/=?^_`{|}~", c) >= 0
}

// emailLocalEnd parses the local part and returns the index of the @ that
// ends it, or -1.
func emailLocalEnd(s string) int {
	i := 0
	for {
		if i >= len(s) {
			return -1
		}
		if s[i] == '"' {
			i++
			for {
				if i >= len(s) {
					return -1
				}
				c := s[i]
				if c == '"' {
					i++
					break
				}
				if c == '\\' {
					if i+1 >= len(s) || s[i+1] > 0x7F {
						return -1
					}
					i += 2
					continue
				}
				if c == 0 || c == '\t' || c == '\n' || c == '\r' || c == ' ' || c > 0x7F {
					return -1
				}
				i++
			}
		} else {
			start := i
			for i < len(s) && isAtext(s[i]) {
				i++
			}
			if i == start {
				return -1
			}
		}
		if i < len(s) && s[i] == '.' {
			i++
			continue
		}
		if i < len(s) && s[i] == '@' {
			return i
		}
		return -1
	}
}

var (
	emailLabel    = regexp.MustCompile(`(?i)^(?:xn--)?[a-z0-9]+(?:-+[a-z0-9]+)*$`)
	emailTopLabel = regexp.MustCompile(`(?i)^(?:[a-z][a-z0-9]*|xn--[a-z0-9]+)(?:-+[a-z0-9]+)*$`)
	emailIPv4     = regexp.MustCompile(`^(?:25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])(?:\.(?:25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])){3}$`)
)

func emailDomainOK(d string) bool {
	if strings.HasPrefix(d, "[") && strings.HasSuffix(d, "]") {
		lit := d[1 : len(d)-1]
		if len(lit) > 5 && strings.EqualFold(lit[:5], "IPv6:") {
			ip := net.ParseIP(lit[5:])
			return ip != nil && strings.Contains(lit[5:], ":")
		}
		return emailIPv4.MatchString(lit)
	}
	labels := strings.Split(d, ".")
	if len(labels) < 2 || len(labels) > 127 {
		return false
	}
	for i, l := range labels {
		if len(l) >= 64 {
			return false
		}
		if i == len(labels)-1 {
			if !emailTopLabel.MatchString(l) {
				return false
			}
			continue
		}
		if !emailLabel.MatchString(l) {
			return false
		}
	}
	return true
}

// urlPattern is Laravel 9's validateUrl pattern (derived from Symfony's
// UrlValidator) rewritten for RE2: the same protocols, optional basic auth,
// a domain name, IPv4 or bracketed IPv6 host, optional port, path, query
// and fragment, matched case-insensitively.
var urlPattern = regexp.MustCompile(`(?i)^` +
	`(aaa|aaas|about|acap|acct|acd|acr|adiumxtra|adt|afp|afs|aim|amss|android|appdata|apt|ark|attachment|aw|barion|beshare|bitcoin|bitcoincash|blob|bolo|browserext|calculator|callto|cap|cast|casts|chrome|chrome-extension|cid|coap|coap\+tcp|coap\+ws|coaps|coaps\+tcp|coaps\+ws|com-eventbrite-attendee|content|conti|crid|cvs|dab|data|dav|diaspora|dict|did|dis|dlna-playcontainer|dlna-playsingle|dns|dntp|dpp|drm|drop|dtn|dvb|ed2k|elsi|example|facetime|fax|feed|feedready|file|filesystem|finger|first-run-pen-experience|fish|fm|ftp|fuchsia-pkg|geo|gg|git|gizmoproject|go|gopher|graph|gtalk|h323|ham|hcap|hcp|http|https|hxxp|hxxps|hydrazone|iax|icap|icon|im|imap|info|iotdisco|ipn|ipp|ipps|irc|irc6|ircs|iris|iris\.beep|iris\.lwz|iris\.xpc|iris\.xpcs|isostore|itms|jabber|jar|jms|keyparc|lastfm|ldap|ldaps|leaptofrogans|lorawan|lvlt|magnet|mailserver|mailto|maps|market|message|mid|mms|modem|mongodb|moz|ms-access|ms-browser-extension|ms-calculator|ms-drive-to|ms-enrollment|ms-excel|ms-eyecontrolspeech|ms-gamebarservices|ms-gamingoverlay|ms-getoffice|ms-help|ms-infopath|ms-inputapp|ms-lockscreencomponent-config|ms-media-stream-id|ms-mixedrealitycapture|ms-mobileplans|ms-officeapp|ms-people|ms-project|ms-powerpoint|ms-publisher|ms-restoretabcompanion|ms-screenclip|ms-screensketch|ms-search|ms-search-repair|ms-secondary-screen-controller|ms-secondary-screen-setup|ms-settings|ms-settings-airplanemode|ms-settings-bluetooth|ms-settings-camera|ms-settings-cellular|ms-settings-cloudstorage|ms-settings-connectabledevices|ms-settings-displays-topology|ms-settings-emailandaccounts|ms-settings-language|ms-settings-location|ms-settings-lock|ms-settings-nfctransactions|ms-settings-notifications|ms-settings-power|ms-settings-privacy|ms-settings-proximity|ms-settings-screenrotation|ms-settings-wifi|ms-settings-workplace|ms-spd|ms-sttoverlay|ms-transit-to|ms-useractivityset|ms-virtualtouchpad|ms-visio|ms-walk-to|ms-whiteboard|ms-whiteboard-cmd|ms-word|msnim|msrp|msrps|mss|mtqp|mumble|mupdate|mvn|news|nfs|ni|nih|nntp|notes|ocf|oid|onenote|onenote-cmd|opaquelocktoken|openpgp4fpr|pack|palm|paparazzi|payto|pkcs11|platform|pop|pres|prospero|proxy|pwid|psyc|pttp|qb|query|redis|rediss|reload|res|resource|rmi|rsync|rtmfp|rtmp|rtsp|rtsps|rtspu|s3|secondlife|service|session|sftp|sgn|shttp|sieve|simpleledger|sip|sips|skype|smb|sms|smtp|snews|snmp|soap\.beep|soap\.beeps|soldat|spiffe|spotify|ssh|steam|stun|stuns|submit|svn|tag|teamspeak|tel|teliaeid|telnet|tftp|tg|things|thismessage|tip|tn3270|tool|ts3server|turn|turns|tv|udp|unreal|urn|ut2004|v-event|vemmi|ventrilo|videotex|vnc|view-source|wais|webcal|wpid|ws|wss|wtai|wyciwyg|xcon|xcon-userid|xfire|xmlrpc\.beep|xmlrpc\.beeps|xmpp|xri|ymsgr|z39\.50|z39\.50r|z39\.50s)://` +
	`(((?:[_.\pL\pN-]|%[0-9A-Fa-f]{2})+:)?((?:[_.\pL\pN-]|%[0-9A-Fa-f]{2})+)@)?` +
	`(` +
	`([\pL\pN\pS\-_.])+(\.?([\pL\pN]|xn--[\pL\pN-]+)+\.?)` +
	`|` +
	`\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}` +
	`|` +
	`\[` + urlIPv6 + `\]` +
	`)` +
	`(:[0-9]+)?` +
	`(?:/(?:[\pL\pN\-._~!$&'()*+,;=:@]|%[0-9A-Fa-f]{2})*)*` +
	`(?:\?(?:[\pL\pN\-._~!$&'\[\]()*+,;=:@/?]|%[0-9A-Fa-f]{2})*)?` +
	`(?:#(?:[\pL\pN\-._~!$&'()*+,;=:@/?]|%[0-9A-Fa-f]{2})*)?` +
	`$`)

const urlIPv6 = `(?:(?:(?:(?:(?:(?:(?:[0-9a-f]{1,4})):){6})(?:(?:(?:(?:(?:[0-9a-f]{1,4})):(?:(?:[0-9a-f]{1,4})))|(?:(?:(?:(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9]))\.){3}(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9])))))))|(?:(?:::(?:(?:(?:[0-9a-f]{1,4})):){5})(?:(?:(?:(?:(?:[0-9a-f]{1,4})):(?:(?:[0-9a-f]{1,4})))|(?:(?:(?:(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9]))\.){3}(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9])))))))|(?:(?:(?:(?:(?:[0-9a-f]{1,4})))?::(?:(?:(?:[0-9a-f]{1,4})):){4})(?:(?:(?:(?:(?:[0-9a-f]{1,4})):(?:(?:[0-9a-f]{1,4})))|(?:(?:(?:(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9]))\.){3}(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9])))))))|(?:(?:(?:(?:(?:(?:[0-9a-f]{1,4})):){0,1}(?:(?:[0-9a-f]{1,4})))?::(?:(?:(?:[0-9a-f]{1,4})):){3})(?:(?:(?:(?:(?:[0-9a-f]{1,4})):(?:(?:[0-9a-f]{1,4})))|(?:(?:(?:(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9]))\.){3}(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9])))))))|(?:(?:(?:(?:(?:(?:[0-9a-f]{1,4})):){0,2}(?:(?:[0-9a-f]{1,4})))?::(?:(?:(?:[0-9a-f]{1,4})):){2})(?:(?:(?:(?:(?:[0-9a-f]{1,4})):(?:(?:[0-9a-f]{1,4})))|(?:(?:(?:(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9]))\.){3}(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9])))))))|(?:(?:(?:(?:(?:(?:[0-9a-f]{1,4})):){0,3}(?:(?:[0-9a-f]{1,4})))?::(?:(?:[0-9a-f]{1,4})):)(?:(?:(?:(?:(?:[0-9a-f]{1,4})):(?:(?:[0-9a-f]{1,4})))|(?:(?:(?:(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9]))\.){3}(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9])))))))|(?:(?:(?:(?:(?:(?:[0-9a-f]{1,4})):){0,4}(?:(?:[0-9a-f]{1,4})))?::)(?:(?:(?:(?:(?:[0-9a-f]{1,4})):(?:(?:[0-9a-f]{1,4})))|(?:(?:(?:(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9]))\.){3}(?:(?:25[0-5]|(?:[1-9]|1[0-9]|2[0-4])?[0-9])))))))|(?:(?:(?:(?:(?:(?:[0-9a-f]{1,4})):){0,5}(?:(?:[0-9a-f]{1,4})))?::)(?:(?:[0-9a-f]{1,4})))|(?:(?:(?:(?:(?:(?:[0-9a-f]{1,4})):){0,6}(?:(?:[0-9a-f]{1,4})))?::))))`