package gdnative

import "C"

import (
	"strings"
	"unicode"
	"unsafe"
)

// unsafeToGoString will convert a null pointer with an underlying CString into
// a Go string.
func unsafeToGoString(p unsafe.Pointer) string {
	// Cast the pointer to a CString.
	cString := (*C.char)(p)
	goString := C.GoString(cString)

	return goString
}

// camelToSnake will convert the given string from camelcase to snake case.
// Attribution:
//   Author: https://github.com/mantenie
//   Source: https://github.com/serenize/snaker
func camelToSnake(s string) string { //nolint:deadcode,unused
	var result string
	var words []string
	var lastPos int
	rs := []rune(s)

	for i := 0; i < len(rs); i++ {
		if i > 0 && unicode.IsUpper(rs[i]) {
			if initialism := startsWithInitialism(s[lastPos:]); initialism != "" {
				words = append(words, initialism)

				i += len(initialism) - 1
				lastPos = i
				continue
			}

			words = append(words, s[lastPos:i])
			lastPos = i
		}
	}

	// append the last word
	if s[lastPos:] != "" {
		words = append(words, s[lastPos:])
	}

	for k, word := range words {
		if k > 0 {
			result += "_"
		}

		result += strings.ToLower(word)
	}

	return result
}

// startsWithInitialism returns the initialism if the given string begins with it
func startsWithInitialism(s string) string { //nolint:unused
	var initialism string
	// the longest initialism is 5 char, the shortest 2
	for i := 1; i <= 5; i++ {
		if len(s) > i-1 && commonInitialisms[s[:i]] {
			initialism = s[:i]
		}
	}
	return initialism
}

// commonInitialisms, taken from
// https://github.com/golang/lint/blob/206c0f020eba0f7fbcfbc467a5eb808037df2ed6/lint.go#L731
var commonInitialisms = map[string]bool{ //nolint:unused
	"ACL":   true,
	"API":   true,
	"ASCII": true,
	"CPU":   true,
	"CSS":   true,
	"DNS":   true,
	"EOF":   true,
	"GUID":  true,
	"HTML":  true,
	"HTTP":  true,
	"HTTPS": true,
	"ID":    true,
	"IP":    true,
	"JSON":  true,
	"LHS":   true,
	"OS":    true,
	"QPS":   true,
	"RAM":   true,
	"RHS":   true,
	"RPC":   true,
	"SLA":   true,
	"SMTP":  true,
	"SQL":   true,
	"SSH":   true,
	"TCP":   true,
	"TLS":   true,
	"TTL":   true,
	"UDP":   true,
	"UI":    true,
	"UID":   true,
	"UUID":  true,
	"URI":   true,
	"URL":   true,
	"UTF8":  true,
	"VM":    true,
	"XML":   true,
	"XMPP":  true,
	"XSRF":  true,
	"XSS":   true,
}