use codeviz_common::ElementFormatter;
use std::collections::BTreeSet;
use super::*;

#[derive(Debug, Clone)]
pub struct FileSpec {
    pub elements: Elements,
}

impl FileSpec {
    pub fn new() -> FileSpec {
        FileSpec { elements: Elements::new() }
    }

    pub fn push<E>(&mut self, element: E)
        where E: Into<Element>
    {
        self.elements.push(element);
    }

    fn imports(&self) -> Option<Elements> {
        let mut imports = BTreeSet::new();

        self.elements.imports(&mut imports);

        let modules: BTreeSet<(String, Option<String>)> =
            imports.into_iter().map(|imported| (imported.module, imported.alias)).collect();

        if modules.is_empty() {
            return None;
        }

        let mut elements = Elements::new();

        for (module, alias) in modules {
            let mut s = Statement::new();

            s.push("use ");
            s.push(&module);

            if let Some(ref alias) = alias {
                s.push(" as ");
                s.push(alias);
            }

            s.push(";");

            elements.push(s);
        }

        Some(elements)
    }

    pub fn format<W>(&self, out: &mut W) -> Result<()>
        where W: ::std::fmt::Write
    {
        let mut elements = Elements::new();

        if let Some(imports) = self.imports() {
            elements.push(imports);
        }

        elements.push(self.elements.clone().join(Spacing));

        let elements: Element = elements.clone().join(Spacing).into();
        let mut extra = ();

        elements.format(&mut ElementFormatter::new(out), &mut extra)?;
        out.write_char('\n')?;

        Ok(())
    }
}

impl ImportReceiver for BTreeSet<ImportedName> {
    fn receive(&mut self, name: &ImportedName) {
        self.insert(name.clone());
    }
}

impl ToString for FileSpec {
    fn to_string(&self) -> String {
        let mut s = String::new();
        self.format(&mut s).unwrap();
        s
    }
}