// Copyright (c) 2019-2024 Delyan Angelov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module vflags

import os
import strings

// join_env_vflags_and_os_args returns all the arguments (the ones from the env variable VFLAGS too), passed on the command line.
pub fn join_env_vflags_and_os_args() []string {
    vosargs := os.getenv('VOSARGS')
    if vosargs != '' {
        return tokenize_to_args(vosargs)
    }
    vflags := os.getenv('VFLAGS')
    if vflags != '' {
        mut args := []string{}
        args << os.args[0]
        args << tokenize_to_args(vflags)
        args << os.args#[1..]
        return args
    }
    return os.args
}

// tokenize_to_args converts the input `s`, into an array of arguments.
// The arguments are separated by one or more spaces in the input `s`.
// The separating spaces are ignored.
// It supports quoted arguments, where "several little words" for example,
// will become a *single argument* in the output.
// The quotes can be single or double ones.
pub fn tokenize_to_args(s string) []string {
    mut tokens := []string{}
    mut ctoken := strings.new_builder(20)
    mut in_quotes := false
    mut quote_char := ` `
    for i in 0 .. s.len {
        c := s[i]
        if !in_quotes && c in [`"`, `'`] {
            in_quotes = true
            quote_char = c
        } else if in_quotes && c == quote_char {
            if i > 0 && s[i - 1] == `\\` {
                // support escaping a quote with a \
                ctoken.go_back(1)
                ctoken.write_rune(c)
            } else {
                in_quotes = false
                tokens << ctoken.str()
            }
        } else if c.is_space() && !in_quotes {
            // space outside quotes means end of a token
            if ctoken.len > 0 {
                tokens << ctoken.str()
            }
        } else {
            // part of a token
            ctoken.write_rune(c)
        }
    }
    // add the potential remaining token too
    if ctoken.len > 0 {
        tokens << ctoken.str()
    }
    return tokens
}