use crate::*;
use alloc::vec::Vec;
use core::convert::TryFrom;
use core::iter::FromIterator;
use core::ops::{Deref, DerefMut};

/// The `SEQUENCE OF` object is an ordered list of homogeneous types.
///
/// This type implements `Deref<Target = [T]>` and `DerefMut<Target = [T]>`, so all methods
/// like `.iter()`, `.len()` and others can be used transparently as if using a vector.
///
/// # Examples
///
/// ```
/// use asn1_rs::SequenceOf;
/// use std::iter::FromIterator;
///
/// // build set
/// let seq = SequenceOf::from_iter([2, 3, 4]);
///
/// // `seq` now contains the serialized DER representation of the array
///
/// // iterate objects
/// let mut sum = 0;
/// for item in seq.iter() {
///     // item has type `Result<u32>`, since parsing the serialized bytes could fail
///     sum += *item;
/// }
/// assert_eq!(sum, 9);
///
/// ```
#[derive(Debug, PartialEq)]
pub struct SequenceOf<T> {
    pub(crate) items: Vec<T>,
}

impl<T> SequenceOf<T> {
    /// Builds a `SEQUENCE OF` from the provided content
    #[inline]
    pub const fn new(items: Vec<T>) -> Self {
        SequenceOf { items }
    }

    /// Converts `self` into a vector without clones or allocation.
    #[inline]
    pub fn into_vec(self) -> Vec<T> {
        self.items
    }

    /// Appends an element to the back of a collection
    #[inline]
    pub fn push(&mut self, item: T) {
        self.items.push(item)
    }
}

impl<T> AsRef<[T]> for SequenceOf<T> {
    fn as_ref(&self) -> &[T] {
        &self.items
    }
}

impl<T> AsMut<[T]> for SequenceOf<T> {
    fn as_mut(&mut self) -> &mut [T] {
        &mut self.items
    }
}

impl<T> Deref for SequenceOf<T> {
    type Target = [T];

    fn deref(&self) -> &Self::Target {
        &self.items
    }
}

impl<T> DerefMut for SequenceOf<T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.items
    }
}

impl<T> From<SequenceOf<T>> for Vec<T> {
    fn from(seq: SequenceOf<T>) -> Self {
        seq.items
    }
}

impl<T> FromIterator<T> for SequenceOf<T> {
    fn from_iter<IT: IntoIterator<Item = T>>(iter: IT) -> Self {
        let items = Vec::from_iter(iter);
        SequenceOf::new(items)
    }
}

impl<'a, T> TryFrom<Any<'a>> for SequenceOf<T>
where
    T: FromBer<'a>,
{
    type Error = Error;

    fn try_from(any: Any<'a>) -> Result<Self> {
        any.tag().assert_eq(Self::TAG)?;
        if !any.header.is_constructed() {
            return Err(Error::ConstructExpected);
        }
        let items = SequenceIterator::<T, BerParser>::new(any.data).collect::<Result<Vec<T>>>()?;
        Ok(SequenceOf::new(items))
    }
}

impl<T> CheckDerConstraints for SequenceOf<T>
where
    T: CheckDerConstraints,
{
    fn check_constraints(any: &Any) -> Result<()> {
        any.tag().assert_eq(Self::TAG)?;
        any.header.assert_constructed()?;
        for item in SequenceIterator::<Any, DerParser>::new(any.data) {
            let item = item?;
            T::check_constraints(&item)?;
        }
        Ok(())
    }
}

impl<T> DerAutoDerive for SequenceOf<T> {}

impl<T> Tagged for SequenceOf<T> {
    const TAG: Tag = Tag::Sequence;
}

#[cfg(feature = "std")]
impl<T> ToDer for SequenceOf<T>
where
    T: ToDer,
{
    fn to_der_len(&self) -> Result<usize> {
        self.items.to_der_len()
    }

    fn write_der_header(&self, writer: &mut dyn std::io::Write) -> SerializeResult<usize> {
        self.items.write_der_header(writer)
    }

    fn write_der_content(&self, writer: &mut dyn std::io::Write) -> SerializeResult<usize> {
        self.items.write_der_content(writer)
    }
}

#[cfg(test)]
mod tests {
    use crate::SequenceOf;
    use core::iter::FromIterator;

    /// Test use of object, available methods and syntax for different use cases
    #[test]
    fn use_sequence_of() {
        let mut set = SequenceOf::from_iter([1, 2, 3]);
        set.push(4);

        // deref as slice
        let sum: i32 = set.iter().sum();
        assert_eq!(sum, 10);

        // range operator
        assert_eq!(&set[1..3], &[2, 3]);
    }
}