use crate::command::command_builder::CommandBuilder;
use crate::command::command_sequence::CommandSequence;

fn parse_quote(characters: &mut Vec<char>) -> Result<String, UnmatchedQuoteError> {
    if characters.is_empty() {
        Err(UnmatchedQuoteError)
    } else {
        let mut quoted_arg = String::default();
        let mut current_char = characters.pop().unwrap();

        while !characters.is_empty() && current_char != '\'' {
            quoted_arg.push(current_char);
            current_char = characters.pop().unwrap();
        }

        Ok(quoted_arg)
    }
}

fn build_argv(characters: &mut Vec<char>, current_arg: &mut String) -> Vec<String> {
    if characters.is_empty() {
        vec![]
    } else {
        let current_char = characters.pop().unwrap();

        if current_char.is_whitespace() {
            if !current_arg.is_empty() {
                let mut argv: Vec<String> = vec![current_arg.clone()];
                argv.append(&mut build_argv(characters, &mut String::from("")));

                argv
            } else {
                build_argv(characters, current_arg)
            }
        } else if current_char == '\'' {
            let mut argv = vec![parse_quote(characters).unwrap()];
            argv.append(&mut build_argv(characters, &mut String::default()));

            argv
        } else {
            current_arg.push(current_char);
            build_argv(characters, current_arg)
        }
    }
}

pub fn parse_command_line(line: String) -> Option<CommandSequence> {
    let mut characters: Vec<char> = line.chars().rev().collect();
    let argv = build_argv(&mut characters, &mut String::default());

    if !argv.is_empty() {
        let command = CommandBuilder::new(argv).build();
        Some(CommandSequence::new(command))
    } else {
        None
    }
}

#[derive(Debug)]
struct UnmatchedQuoteError;