use std::mem::replace;
use std::collections::HashMap;
use super::{Object, Props};
use super::tokenizer::{Tokenizer, Token};

pub struct Parser {
    tokenizer: Tokenizer,
    object_name: Option<String>,
    current_key: Option<String>,
    current_prop: Option<String>,
    props: Props,
    content: HashMap<String, (Props, String)>,
}

impl Parser {
    pub fn new() -> Self {
        Parser {
            tokenizer: Tokenizer::new(),
            object_name: None,
            current_key: None,
            current_prop: None,
            props: vec![],
            content: HashMap::new(),
        }
    }

    pub fn feed<F>(&mut self, input: &'_ [u8], mut f: F)
    where
        F: FnMut(Object),
    {
        let current_key = &mut self.current_key;
        let current_prop = &mut self.current_prop;
        let props = &mut self.props;
        let object_name = &mut self.object_name;
        let content = &mut self.content;
        self.tokenizer.feed(input, |token| {
            match token {
                Token::Key(key) => *current_key = Some(key),
                Token::PropName(name) => *current_prop = Some(name),
                Token::PropValue(value) => {
                    current_prop.take().map(|name| {
                        props.push((name, value));
                    });
                }
                Token::Value(value) => {
                    fn compare(s1: &Option<String>, s2: &str) -> bool {
                        s1.as_ref().map(|s1| s1 == s2).unwrap_or(s2.len() == 0)
                    }

                    if compare(current_key, "BEGIN") {
                        *object_name = Some(value);
                        content.clear();
                    } else if compare(current_key, "END") {
                        let object_name = replace(object_name, None);
                        let content = replace(content, HashMap::new());
                        object_name.map(|name| f(Object { name, content }));
                    } else {
                        let props = replace(props, vec![]);
                        let key = replace(current_key, None);
                        key.map(|key| content.insert(key, (props, value)));
                    }
                }
            }
        });
    }
}

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

    #[test]
    fn parse_event() {
        let mut p = Parser::new();
        let mut obj = None;
        p.feed(b"BEGIN:VEVENT
SUMMARY:Test event
DTSTART:19700101
END:VEVENT

", |o| {
    assert!(obj.is_none());
    obj = Some(o);
});
        assert_eq!(obj, Some(Object {
            name: "VEVENT".to_owned(),
            content: [("SUMMARY", "Test event"),
                      ("DTSTART", "19700101")]
                .iter()
                .cloned()
                .map(|(k, v)| (k.to_owned(), (vec![], v.to_owned())))
                .collect(),
        }));
    }
}