use num_bigint::BigInt;
use std::io;

use crate::AtomClass;
use crate::CompoundClass;
use crate::Domain;
use crate::DomainEncode;
use crate::IOValueDomainCodec;
use crate::SignedInteger;
use crate::ValueClass;
use crate::boundary as B;
use crate::signed_integer::SignedIntegerRepr;
use crate::ValueImpl;

pub trait Writer {
    fn boundary(&mut self, b: &B::Type) -> io::Result<()>;

    fn start_annotations(&mut self) -> io::Result<()>;
    fn end_annotations(&mut self) -> io::Result<()>;

    fn write_bool(&mut self, v: bool) -> io::Result<()>;

    fn write_f32(&mut self, v: f32) -> io::Result<()>;
    fn write_f64(&mut self, v: f64) -> io::Result<()>;

    fn write_i128(&mut self, v: i128) -> io::Result<()>;
    fn write_u128(&mut self, v: u128) -> io::Result<()>;
    fn write_int(&mut self, v: &BigInt) -> io::Result<()>;

    fn write_string(&mut self, v: &str) -> io::Result<()>;
    fn write_bytes(&mut self, v: &[u8]) -> io::Result<()>;
    fn write_symbol(&mut self, v: &str) -> io::Result<()>;

    fn start_record(&mut self) -> io::Result<()>;
    fn end_record(&mut self) -> io::Result<()>;

    fn start_sequence(&mut self) -> io::Result<()>;
    fn end_sequence(&mut self) -> io::Result<()>;

    fn start_set(&mut self) -> io::Result<()>;
    fn end_set(&mut self) -> io::Result<()>;

    fn start_dictionary(&mut self) -> io::Result<()>;
    fn end_dictionary(&mut self) -> io::Result<()>;

    fn start_embedded(&mut self) -> io::Result<()>;
    fn end_embedded(&mut self) -> io::Result<()>;

    fn flush(&mut self) -> io::Result<()>;

    //---------------------------------------------------------------------------

    fn write_i8(&mut self, v: i8) -> io::Result<()> { self.write_i128(v as i128) }
    fn write_u8(&mut self, v: u8) -> io::Result<()> { self.write_u128(v as u128) }
    fn write_i16(&mut self, v: i16) -> io::Result<()> { self.write_i128(v as i128) }
    fn write_u16(&mut self, v: u16) -> io::Result<()> { self.write_u128(v as u128) }
    fn write_i32(&mut self, v: i32) -> io::Result<()> { self.write_i128(v as i128) }
    fn write_u32(&mut self, v: u32) -> io::Result<()> { self.write_u128(v as u128) }
    fn write_i64(&mut self, v: i64) -> io::Result<()> { self.write_i128(v as i128) }
    fn write_u64(&mut self, v: u64) -> io::Result<()> { self.write_u128(v as u128) }

    fn write_signed_integer(&mut self, v: &SignedInteger) -> io::Result<()> {
        match v.repr() {
            SignedIntegerRepr::I128(i) => self.write_i128(*i),
            SignedIntegerRepr::U128(u) => self.write_u128(*u),
            SignedIntegerRepr::Big(n) => self.write_int(n),
        }
    }

    fn specialized(&mut self) -> Option<(&str, &mut dyn io::Write)> { None }
}

pub fn write_value<D: Domain>(
    w: &mut dyn Writer,
    v: &dyn ValueImpl<D>,
    enc: &mut dyn DomainEncode<D>,
) -> io::Result<()> {
    let annotations = v.annotations();
    let mut annotation_b = B::Type::default();

    let has_annotations = if let Some(anns) = annotations {
        if anns.is_empty() {
            false
        } else {
            w.start_annotations()?;
            for ann in &anns[..] {
                annotation_b.shift(Some(B::Item::Annotation));
                w.boundary(&annotation_b)?;
                ann.write(w, &mut IOValueDomainCodec)?;
            }
            annotation_b.shift(Some(B::Item::AnnotatedValue));
            w.boundary(&annotation_b)?;
            true
        }
    } else {
        false
    };

    match v.value_class() {
        ValueClass::Atomic(a) => match a {
            AtomClass::Boolean => w.write_bool(v.as_boolean().unwrap())?,
            AtomClass::Float => w.write_f32(v.as_float().unwrap())?,
            AtomClass::Double => w.write_f64(v.as_double().unwrap())?,
            AtomClass::SignedInteger => w.write_signed_integer(&v.as_signed_integer().unwrap())?,
            AtomClass::String => w.write_string(&v.as_string().unwrap())?,
            AtomClass::ByteString => w.write_bytes(&v.as_bytestring().unwrap())?,
            AtomClass::Symbol => w.write_symbol(&v.as_symbol().unwrap())?,
        }
        ValueClass::Compound(c) => match c {
            CompoundClass::Record => {
                w.start_record()?;
                let mut b = B::start(B::Item::RecordLabel);
                w.boundary(&b)?;
                v.label().write(w, enc)?;
                for e in v.iter() {
                    b.shift(Some(B::Item::RecordField));
                    w.boundary(&b)?;
                    e.write(w, enc)?;
                }
                b.shift(None);
                w.boundary(&b)?;
                w.end_record()?
            }
            CompoundClass::Sequence => {
                w.start_sequence()?;
                let mut b = B::Type::default();
                for e in v.iter() {
                    b.shift(Some(B::Item::SequenceValue));
                    w.boundary(&b)?;
                    e.write(w, enc)?;
                }
                b.shift(None);
                w.boundary(&b)?;
                w.end_sequence()?
            }
            CompoundClass::Set => {
                w.start_set()?;
                let mut b = B::Type::default();
                for e in v.iter() {
                    b.shift(Some(B::Item::SetValue));
                    w.boundary(&b)?;
                    e.write(w, enc)?;
                }
                b.shift(None);
                w.boundary(&b)?;
                w.end_set()?
            }
            CompoundClass::Dictionary => {
                w.start_dictionary()?;
                let mut b = B::Type::default();
                for (k, v) in v.entries() {
                    b.shift(Some(B::Item::DictionaryKey));
                    w.boundary(&b)?;
                    k.write(w, enc)?;
                    b.shift(Some(B::Item::DictionaryValue));
                    w.boundary(&b)?;
                    v.write(w, enc)?;
                }
                b.shift(None);
                w.boundary(&b)?;
                w.end_dictionary()?
            }
        }
        ValueClass::Embedded => {
            w.start_embedded()?;
            enc.encode_embedded(w, &v.as_embedded().unwrap())?;
            w.end_embedded()?
        }
    }

    if has_annotations {
        annotation_b.shift(None);
        w.boundary(&annotation_b)?;
        w.end_annotations()?
    }

    Ok(())
}