use super::types::*;
use chumsky::text::Char;
use log;
use lyn::Scanner;

pub fn scan(source: String) -> Tokens {
    let mut scanner = Scanner::new(&source);
    let mut tokens = Vec::new();

    loop {
        let start = scanner.cursor();
        if let Some(c) = scanner.pop() {
            match *c {
                ',' => tokens.push(LocatedToken {
                    start,
                    end: scanner.cursor(),
                    token: Token::Comma,
                }),
                ':' => tokens.push(LocatedToken {
                    start,
                    end: scanner.cursor(),
                    token: Token::Colon,
                }),
                ';' => tokens.push(LocatedToken {
                    start,
                    end: scanner.cursor(),
                    token: Token::Semicolon,
                }),
                '{' => tokens.push(LocatedToken {
                    start,
                    end: scanner.cursor(),
                    token: Token::OpenCurly,
                }),
                '}' => tokens.push(LocatedToken {
                    start,
                    end: scanner.cursor(),
                    token: Token::CloseCurly,
                }),
                '(' => tokens.push(LocatedToken {
                    start,
                    end: scanner.cursor(),
                    token: Token::OpenParen,
                }),
                ')' => tokens.push(LocatedToken {
                    start,
                    end: scanner.cursor(),
                    token: Token::CloseParen,
                }),
                '[' => tokens.push(LocatedToken {
                    start,
                    end: scanner.cursor(),
                    token: Token::OpenBracket,
                }),
                ']' => tokens.push(LocatedToken {
                    start,
                    end: scanner.cursor(),
                    token: Token::CloseBracket,
                }),
                '=' => tokens.push(LocatedToken {
                    start,
                    end: scanner.cursor(),
                    token: Token::Equals,
                }),
                // labels
                '.' => {
                    let mut str = "".to_string();
                    loop {
                        if let Some(ch) = scanner.peek()
                            && !ch.is_alphanumeric()
                            && *ch != '_'
                        {
                            break;
                        }
                        if let Some(ch) = scanner.pop() {
                            str.push(*ch);
                        } else {
                            break;
                        }
                    }

                    tokens.push(LocatedToken {
                        start,
                        end: scanner.cursor(),
                        token: match str.as_str() {
                            _ => Token::Label(str),
                        },
                    });
                }
                // comments
                '#' => {
                    let mut str = "".to_string();
                    while let Some(ch) = scanner.pop() {
                        if ch.is_newline() {
                            break;
                        }
                        str.push(*ch);
                    }
                }
                // strings
                '"' => {
                    let mut str = "".to_string();
                    while let Some(ch) = scanner.pop() {
                        if *ch == '"' {
                            break;
                        }
                        str.push(*ch);
                    }
                    tokens.push(LocatedToken {
                        start,
                        end: scanner.cursor(),
                        token: Token::String(str),
                    });
                }
                // whitespace
                _ if c.is_whitespace() => {}
                // numbers
                _ if c.is_numeric() => {
                    let mut str = c.to_string();
                    loop {
                        if let Some(ch) = scanner.peek()
                            && !ch.is_numeric()
                        {
                            break;
                        }
                        if let Some(ch) = scanner.pop() {
                            str.push(*ch);
                        } else {
                            break;
                        }
                    }
                    let i = str.parse::<u32>().unwrap();
                    tokens.push(LocatedToken {
                        start,
                        end: scanner.cursor(),
                        token: Token::Number(i),
                    });
                }
                // identifiers and keywords
                _ if c.is_alphabetic() || *c == '_' => {
                    let mut str = c.to_string();
                    loop {
                        if let Some(ch) = scanner.peek()
                            && !ch.is_alphanumeric()
                            && *ch != '_'
                        {
                            break;
                        }
                        if let Some(ch) = scanner.pop() {
                            str.push(*ch);
                        } else {
                            break;
                        }
                    }

                    tokens.push(LocatedToken {
                        start,
                        end: scanner.cursor(),
                        token: match str.as_str() {
                            "fn" => Token::Fn,
                            "let" => Token::Let,
                            "mut" => Token::Mut,
                            "return" => Token::Return,
                            "true" => Token::True,
                            "false" => Token::False,
                            _ => Token::Identifier(str),
                        },
                    });
                }
                // error
                _ => {
                    log::error!("Unexpected character: {c}");
                }
            }
        } else {
            break;
        }
    }

    tokens.into()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn let_number() {
        let program = "let x = 108;".to_string();
        let mut result = scan(program)
            .0
            .into_iter()
            .map(|t| t.token)
            .collect::<Vec<_>>();
        result.reverse();
        insta::assert_debug_snapshot!(result);
    }

    #[test]
    fn let_fn() {
        let program = "
let main = fn (x) {
  console.log(x);
};"
        .to_string();
        let mut result = scan(program)
            .0
            .into_iter()
            .map(|t| t.token)
            .collect::<Vec<_>>();
        result.reverse();
        insta::assert_debug_snapshot!(result);
    }

    #[test]
    fn scaffolding() {
        let program = "
let init = fn() {
  return {
    player: { position: { x: 10, y: 20 }, },
  }
};

let update = fn(state, events) {
  return state';
};

let draw = fn(frame, state) {
  frame.clear(0,0,0);
};

let migrate = fn(state) {
    return { player: { pos: state.player.position } },
};
"
        .to_string();
        let mut result = scan(program)
            .0
            .into_iter()
            .map(|t| t.token)
            .collect::<Vec<_>>();
        result.reverse();
        insta::assert_debug_snapshot!(result);
    }
    /*
    // Errors

    #[test]
    fn duplicate_toplevel_defs() {
        let program = vec![
            helpers::define_expr("main", "record".into()),
            helpers::define_expr("main", 0.into()),
        ]
        .into();
        let result = run(program);
        assert_eq!(result, Err(Error::DuplicateNames("main".into())));
    }
    */
}