// Copyright (c) 2019-2023 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module strings

/*
pub struct Builder {
mut:
    buf []u8
pub mut:
    len          int
    initial_size int = 1
}*/

pub type Builder = []u8

pub fn new_builder(initial_size int) Builder {
    return []u8{cap: initial_size}
}

pub fn (mut b Builder) write_byte(data byte) {
    b << data
}

pub fn (mut b Builder) clear() {
    b = []u8{cap: b.cap}
}

pub fn (mut b Builder) write_u8(data u8) {
    b << data
}

pub fn (mut b Builder) write(data []u8) ?int {
    if data.len == 0 {
        return 0
    }
    b << data
    return data.len
}

pub fn (b &Builder) byte_at(n int) u8 {
    unsafe {
        return b[n]
    }
}

pub fn (mut b Builder) write_string(s string) {
    if s.len == 0 {
        return
    }

    for c in s {
        b << c
    }
}

pub fn (mut b Builder) writeln(s string) {
    if s.len > 0 {
        b.write_string(s)
    }

    b << 10
}

pub fn (mut b Builder) str() string {
    s := ''

    #for (const c of b.val.arr.arr)
    #s.str += String.fromCharCode(+c)
    b.trim(0)
    return s
}

pub fn (mut b Builder) cut_last(n int) string {
    cut_pos := b.len - n
    x := b[cut_pos..]
    res := x.bytestr()
    b.trim(cut_pos)
    return res
}

pub fn (mut b Builder) go_back_to(pos int) {
    b.trim(pos)
}

// go_back discards the last `n` bytes from the buffer
pub fn (mut b Builder) go_back(n int) {
    b.trim(b.len - n)
}

// cut_to cuts the string after `pos` and returns it.
// if `pos` is superior to builder length, returns an empty string
// and cancel further operations
pub fn (mut b Builder) cut_to(pos int) string {
    if pos > b.len {
        return ''
    }
    return b.cut_last(b.len - pos)
}

pub fn (mut b Builder) write_runes(runes []rune) {
    for r in runes {
        res := r.str()
        #res.str = String.fromCharCode(r.val)
        b << res.bytes()
    }
}

// after(6) returns 'world'
// buf == 'hello world'
pub fn (mut b Builder) after(n int) string {
    if n >= b.len {
        return ''
    }

    x := b.slice(n, b.len)
    return x.bytestr()
}

// last_n(5) returns 'world'
// buf == 'hello world'
pub fn (b &Builder) last_n(n int) string {
    if n >= b.len {
        return ''
    }

    x := b.slice(b.len - n, b.len)
    return x.bytestr()
}