module builtin

pub struct string {
pub:
	str JS.String
	len int
}

pub fn (s string) slice(a int, b int) string {
	return string(s.str.slice(a, b))
}

pub fn (s string) after(dot string) string {
	return string(s.str.slice(s.str.lastIndexOf(dot.str) + 1, int(s.str.length)))
}

pub fn (s string) after_char(dot byte) string {
	// TODO: Implement after byte
	return s
}

pub fn (s string) all_after(dot string) string {
	return string(s.str.slice(s.str.indexOf(dot.str) + 1, int(s.str.length)))
}

// why does this exist?
pub fn (s string) all_after_last(dot string) string {
	return s.after(dot)
}

pub fn (s string) all_before(dot string) string {
	return string(s.str.slice(0, s.str.indexOf(dot.str)))
}

pub fn (s string) all_before_last(dot string) string {
	return string(s.str.slice(0, s.str.lastIndexOf(dot.str)))
}

pub fn (s string) bool() bool {
	return s == 'true'
}

pub fn (s string) split(dot string) []string {
	mut arr := s.str.split(dot.str).map(string(it))
	#arr = new array(arr)

	return arr
}

pub fn (s string) bytes() []byte {
	sep := ''
	mut arr := s.str.split(sep.str).map(it.charCodeAt(0))
	#arr = new array(arr)

	return arr
}

pub fn (s string) capitalize() string {
	part := string(s.str.slice(1, int(s.str.length)))
	return string(s.str.charAt(0).toUpperCase().concat(part.str))
}

pub fn (s string) clone() string {
	return string(s.str)
}

pub fn (s string) contains(substr string) bool {
	return s.str.includes(substr.str)
}

pub fn (s string) contains_any(chars string) bool {
	sep := ''
	for x in chars.str.split(sep.str) {
		if s.str.includes(x) {
			return true
		}
	}
	return false
}

pub fn (s string) contains_any_substr(chars []string) bool {
	for x in chars {
		if s.str.includes(x.str) {
			return true
		}
	}
	return false
}

pub fn (s string) count(substr string) int {
	// TODO: "error: `[]JS.String` is not a struct" when returning arr.length or arr.len
	arr := s.str.split(substr.str)
	return native_str_arr_len(arr)
}

pub fn (s string) ends_with(p string) bool {
	return s.str.endsWith(p.str)
}

pub fn (s string) starts_with(p string) bool {
	return s.str.startsWith(p.str)
}

pub fn (s string) fields() []string {
	mut res := []string{}
	mut word_start := 0
	mut word_len := 0
	mut is_in_word := false
	mut is_space := false
	for i, c in s {
		is_space = c in [32, 9, 10]
		if !is_space {
			word_len++
		}
		if !is_in_word && !is_space {
			word_start = i
			is_in_word = true
			continue
		}
		if is_space && is_in_word {
			res << s[word_start..word_start + word_len]
			is_in_word = false
			word_len = 0
			word_start = 0
			continue
		}
	}
	if is_in_word && word_len > 0 {
		// collect the remainder word at the end
		res << s[word_start..s.len]
	}
	return res
}

pub fn (s string) find_between(start string, end string) string {
	return string(s.str.slice(s.str.indexOf(start.str), s.str.indexOf(end.str) + 1))
}

// unnecessary in the JS backend, implemented for api parity.
pub fn (s string) free() {}

pub fn (s string) hash() int {
	mut h := u32(0)
	if h == 0 && s.len > 0 {
		for c in s {
			h = h * 31 + u32(c)
		}
	}
	return int(h)
}

// int returns the value of the string as an integer `'1'.int() == 1`.
pub fn (s string) int() int {
	return int(JS.parseInt(s))
}

// i64 returns the value of the string as i64 `'1'.i64() == i64(1)`.
pub fn (s string) i64() i64 {
	return i64(JS.parseInt(s))
}

// i8 returns the value of the string as i8 `'1'.i8() == i8(1)`.
pub fn (s string) i8() i8 {
	return i8(JS.parseInt(s))
}

// i16 returns the value of the string as i16 `'1'.i16() == i16(1)`.
pub fn (s string) i16() i16 {
	return i16(JS.parseInt(s))
}

// f32 returns the value of the string as f32 `'1.0'.f32() == f32(1)`.
pub fn (s string) f32() f32 {
	// return C.atof(&char(s.str))
	return f32(JS.parseFloat(s))
}

// f64 returns the value of the string as f64 `'1.0'.f64() == f64(1)`.
pub fn (s string) f64() f64 {
	return f64(JS.parseFloat(s))
}

// u16 returns the value of the string as u16 `'1'.u16() == u16(1)`.
pub fn (s string) u16() u16 {
	return u16(JS.parseInt(s))
}

// u32 returns the value of the string as u32 `'1'.u32() == u32(1)`.
pub fn (s string) u32() u32 {
	return u32(JS.parseInt(s))
}

// u64 returns the value of the string as u64 `'1'.u64() == u64(1)`.
pub fn (s string) u64() u64 {
	return u64(JS.parseInt(s))
}

// trim_right strips any of the characters given in `cutset` from the right of the string.
// Example: assert ' Hello V d'.trim_right(' d') == ' Hello V'
pub fn (s string) trim_right(cutset string) string {
	if s.len < 1 || cutset.len < 1 {
		return s.clone()
	}

	mut pos := s.len - 1

	for pos >= 0 {
		mut found := false
		for cs in cutset {
			if s[pos] == cs {
				found = true
			}
		}
		if !found {
			break
		}
		pos--
	}

	if pos < 0 {
		return ''
	}

	return s[..pos + 1]
}

// trim_left strips any of the characters given in `cutset` from the left of the string.
// Example: assert 'd Hello V developer'.trim_left(' d') == 'Hello V developer'
[direct_array_access]
pub fn (s string) trim_left(cutset string) string {
	if s.len < 1 || cutset.len < 1 {
		return s.clone()
	}
	mut pos := 0
	for pos < s.len {
		mut found := false
		for cs in cutset {
			if s[pos] == cs {
				found = true
				break
			}
		}
		if !found {
			break
		}
		pos++
	}
	return s[pos..]
}

// trim_prefix strips `str` from the start of the string.
// Example: assert 'WorldHello V'.trim_prefix('World') == 'Hello V'
pub fn (s string) trim_prefix(str string) string {
	if s.starts_with(str) {
		return s[str.len..]
	}
	return s.clone()
}

// trim_suffix strips `str` from the end of the string.
// Example: assert 'Hello VWorld'.trim_suffix('World') == 'Hello V'
pub fn (s string) trim_suffix(str string) string {
	if s.ends_with(str) {
		return s[..s.len - str.len]
	}
	return s.clone()
}

// compare_strings returns `-1` if `a < b`, `1` if `a > b` else `0`.
pub fn compare_strings(a &string, b &string) int {
	if a < b {
		return -1
	}
	if a > b {
		return 1
	}
	return 0
}

// compare_strings_reverse returns `1` if `a < b`, `-1` if `a > b` else `0`.
fn compare_strings_reverse(a &string, b &string) int {
	if a < b {
		return 1
	}
	if a > b {
		return -1
	}
	return 0
}

// compare_strings_by_len returns `-1` if `a.len < b.len`, `1` if `a.len > b.len` else `0`.
fn compare_strings_by_len(a &string, b &string) int {
	if a.len < b.len {
		return -1
	}
	if a.len > b.len {
		return 1
	}
	return 0
}

// compare_lower_strings returns the same as compare_strings but converts `a` and `b` to lower case before comparing.
fn compare_lower_strings(a &string, b &string) int {
	aa := a.to_lower()
	bb := b.to_lower()
	return compare_strings(&aa, &bb)
}

// at returns the byte at index `idx`.
// Example: assert 'ABC'.at(1) == byte(`B`)
fn (s string) at(idx int) byte {
	mut result := byte(0)
	#result = new byte(s.str.charCodeAt(result))

	return result
}

pub fn (s string) to_lower() string {
	mut result := ''
	#let str = s.str.toLowerCase()
	#result = new string(str)

	return result
}

// TODO: check if that behaves the same as V's own string.replace(old_sub,new_sub):
pub fn (s string) replace(old_sub string, new_sub string) string {
	mut result := ''
	#result = new string( s.str.replaceAll(old_sub.str, new_sub.str) )

	return result
}

pub fn (s string) to_upper() string {
	mut result := ''
	#let str = s.str.toUpperCase()
	#result = new string(str)

	return result
}

// sort sorts the string array.
pub fn (mut s []string) sort() {
	s.sort_with_compare(compare_strings)
}

// sort_ignore_case sorts the string array using case insesitive comparing.
pub fn (mut s []string) sort_ignore_case() {
	s.sort_with_compare(compare_lower_strings)
}

// sort_by_len sorts the the string array by each string's `.len` length.
pub fn (mut s []string) sort_by_len() {
	s.sort_with_compare(compare_strings_by_len)
}

// str returns a copy of the string
pub fn (s string) str() string {
	return s.clone()
}

pub fn (s string) repeat(count int) string {
	mut result := ''
	#result = new string(s.str.repeat(count))

	return result
}

// TODO(playX): Use this iterator instead of using .split('').map(c => byte(c))
#function string_iterator(string) { this.stringIteratorFieldIndex = 0; this.stringIteratorIteratedString = string.str; }
#string_iterator.prototype.next = function next() {
#var done = true;
#var value = undefined;
#var position = this.stringIteratorFieldIndex;
#if (position !== -1) {
#var string = this.stringIteratorIteratedString;
#var length = string.length >>> 0;
#if (position >= length) {
#this.stringIteratorFieldIndex = -1;
#} else {
#done = false;
#var first = string.charCodeAt(position);
#if (first < 0xD800 || first > 0xDBFF || position + 1 === length)
#value = new byte(string[position]);
#else {
#value = new byte(string[position]+string[position+1])
#}
#this.stringIteratorFieldIndex = position + value.length;
#}
#}
#return {
#value, done
#}
#}
#string.prototype[Symbol.iterator] = function () { return new string_iterator(this) }

// TODO: Make these functions actually work.
// strip_margin allows multi-line strings to be formatted in a way that removes white-space
// before a delimeter. by default `|` is used.
// Note: the delimiter has to be a byte at this time. That means surrounding
// the value in ``.
//
// Example:
// st := 'Hello there,
// |this is a string,
// |    Everything before the first | is removed'.strip_margin()
// Returns:
// Hello there,
// this is a string,
// Everything before the first | is removed
pub fn (s string) strip_margin() string {
	return s.strip_margin_custom(`|`)
}

// strip_margin_custom does the same as `strip_margin` but will use `del` as delimiter instead of `|`
[direct_array_access]
pub fn (s string) strip_margin_custom(del byte) string {
	mut sep := del
	if sep.is_space() {
		eprintln('Warning: `strip_margin` cannot use white-space as a delimiter')
		eprintln('    Defaulting to `|`')
		sep = `|`
	}
	// don't know how much space the resulting string will be, but the max it
	// can be is this big
	mut ret := []byte{}
	#ret = new array()

	mut count := 0
	for i := 0; i < s.len; i++ {
		if s[i] in [10, 13] {
			unsafe {
				ret[count] = s[i]
			}
			count++
			// CRLF
			if s[i] == 13 && i < s.len - 1 && s[i + 1] == 10 {
				unsafe {
					ret[count] = s[i + 1]
				}
				count++
				i++
			}
			for s[i] != sep {
				i++
				if i >= s.len {
					break
				}
			}
		} else {
			unsafe {
				ret[count] = s[i]
			}
			count++
		}
	}
	/*
	unsafe {
		ret[count] = 0
		return ret.vstring_with_len(count)
	}*/
	mut result := ''
	#for (let x of ret.arr) result.str += String.fromCharCode(x.val)

	return result
}