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//! Candles CSV iterator.

use super::Candle;

/// CSV Candle header.
pub static HEADER: &'static str = "Date,Open,High,Low,Close,Volume\n";

/// CSV Candles iterator.
pub struct CsvIterator<I> {
    inner: I,
    header: bool,
}

impl<I> From<I> for CsvIterator<I>
where
    I: Iterator,
    I::Item: AsRef<Candle>,
{
    fn from(iter: I) -> Self {
        CsvIterator {
            inner: iter,
            header: false,
        }
    }
}

impl<I> Iterator for CsvIterator<I>
where
    I: Iterator,
    I::Item: AsRef<Candle>,
{
    type Item = String;

    fn next(&mut self) -> Option<Self::Item> {
        if !self.header {
            self.header = true;
            Some(HEADER.to_owned())
        } else {
            self.inner.next().map(|candle| candle.as_ref().into())
        }
    }
}

/// Converts into CSV iterator.
pub trait IntoCsvIterator<I> {
    /// Consumes snapshot to creates CSV iterator.
    fn into_csv_iter(self) -> CsvIterator<I>;
}

impl<T> IntoCsvIterator<T::IntoIter> for T
where
    T: IntoIterator,
{
    fn into_csv_iter(self) -> CsvIterator<T::IntoIter> {
        CsvIterator {
            inner: self.into_iter(),
            header: false,
        }
    }
}