use num;
use num::bigint::BigInt;
use std::io::Error;
use super::signed_integer::SignedIntegerRepr;
use super::value::{Domain, Value, NestedValue, IOValue, UnwrappedIOValue, Float, Double};

pub type Result<T> = std::result::Result<T, Error>;

pub trait Writer {
    type Pointer;
    type Annotation;
    type Compound;
    type Dictionary;
    type StreamedAtom;
    type KeyPointer;

    fn supports_streaming(&self) -> bool;

    fn align(&mut self, natural_chunksize: u64) -> Result<()>;

    fn start_annotation(&mut self) -> Result<Self::Annotation>;
    fn extend_annotation(&mut self, a: &mut Self::Annotation, annotation: &IOValue) -> Result<()>;
    fn end_annotation(&mut self, a: Self::Annotation, value_p: Self::Pointer) -> Result<Self::Pointer>;

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

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

    fn write_i8(&mut self, v: i8) -> Result<Self::Pointer>;
    fn write_u8(&mut self, v: u8) -> Result<Self::Pointer>;
    fn write_i16(&mut self, v: i16) -> Result<Self::Pointer>;
    fn write_u16(&mut self, v: u16) -> Result<Self::Pointer>;
    fn write_i32(&mut self, v: i32) -> Result<Self::Pointer>;
    fn write_u32(&mut self, v: u32) -> Result<Self::Pointer>;
    fn write_i64(&mut self, v: i64) -> Result<Self::Pointer>;
    fn write_u64(&mut self, v: u64) -> Result<Self::Pointer>;
    fn write_i128(&mut self, v: i128) -> Result<Self::Pointer>;
    fn write_u128(&mut self, v: u128) -> Result<Self::Pointer>;
    fn write_int(&mut self, v: &BigInt) -> Result<Self::Pointer>;

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

    fn stream_string(&mut self) -> Result<Option<Self::StreamedAtom>>;
    fn stream_bytes(&mut self) -> Result<Option<Self::StreamedAtom>>;
    fn stream_symbol(&mut self) -> Result<Option<Self::StreamedAtom>>;
    fn extend_atom(&mut self, s: &mut Self::StreamedAtom, bs: &[u8]) -> Result<()>;
    fn end_atom(&mut self, s: Self::StreamedAtom) -> Result<Self::Pointer>;

    fn start_record(&mut self, field_count: u64) -> Result<Self::Compound>;
    fn start_sequence(&mut self, item_count: u64) -> Result<Self::Compound>;
    fn start_set(&mut self, item_count: u64) -> Result<Self::Compound>;
    fn stream_record(&mut self) -> Result<Option<Self::Compound>>;
    fn stream_sequence(&mut self) -> Result<Option<Self::Compound>>;
    fn stream_set(&mut self) -> Result<Option<Self::Compound>>;
    fn extend_compound(&mut self, s: &mut Self::Compound, value_p: Self::Pointer) -> Result<()>;
    fn end_compound(&mut self, s: Self::Compound) -> Result<Self::Pointer>;

    fn start_dictionary(&mut self, entry_count: u64) -> Result<Self::Dictionary>;
    fn stream_dictionary(&mut self) -> Result<Option<Self::Dictionary>>;
    fn extend_dictionary_key(&mut self, s: &mut Self::Dictionary, key_p: Self::Pointer) -> Result<Self::KeyPointer>;
    fn extend_dictionary_value(&mut self, s: &mut Self::Dictionary, key_p: Self::KeyPointer, value_p: Self::Pointer) -> Result<()>;
    fn end_dictionary(&mut self, s: Self::Dictionary) -> Result<Self::Pointer>;

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

    fn write(&mut self, v: &IOValue) -> Result<Self::Pointer> {
        match v.annotations().maybe_slice() {
            None => self.write_value(v.value()),
            Some(anns) => {
                let mut a = self.start_annotation()?;
                for ann in anns {
                    self.extend_annotation(&mut a, ann)?;
                }
                let p = self.write_value(v.value())?;
                self.end_annotation(a, p)
            }
        }
    }

    fn write_value(&mut self, v: &UnwrappedIOValue) -> Result<Self::Pointer> {
        match v {
            Value::Boolean(b) => self.write_bool(*b),
            Value::Float(Float(f)) => self.write_f32(*f),
            Value::Double(Double(d)) => self.write_f64(*d),
            Value::SignedInteger(n) => match n.repr() {
                SignedIntegerRepr::I128(i) => self.write_i128(*i),
                SignedIntegerRepr::U128(u) => self.write_u128(*u),
                SignedIntegerRepr::Big(ref n) => self.write_int(n),
            }
            Value::String(ref s) => self.write_string(s),
            Value::ByteString(ref bs) => self.write_bytes(bs),
            Value::Symbol(ref s) => self.write_symbol(s),
            Value::Record(r) => {
                let mut c = self.start_record(r.arity() as u64)?;
                let p = self.write(r.label())?;
                self.extend_compound(&mut c, p)?;
                for f in r.fields() {
                    let p = self.write(f)?;
                    self.extend_compound(&mut c, p)?;
                }
                self.end_compound(c)
            }
            Value::Sequence(ref vs) => {
                let mut c = self.start_sequence(vs.len() as u64)?;
                for v in vs {
                    let p = self.write(v)?;
                    self.extend_compound(&mut c, p)?;
                }
                self.end_compound(c)
            }
            Value::Set(ref vs) => {
                let mut c = self.start_set(vs.len() as u64)?;
                for v in vs {
                    let p = self.write(v)?;
                    self.extend_compound(&mut c, p)?;
                }
                self.end_compound(c)
            }
            Value::Dictionary(ref vs) => {
                let mut d = self.start_dictionary(vs.len() as u64)?;
                for (k, v) in vs {
                    let p = self.write(k)?;
                    let kp = self.extend_dictionary_key(&mut d, p)?;
                    let p = self.write(v)?;
                    self.extend_dictionary_value(&mut d, kp, p)?;
                }
                self.end_dictionary(d)
            }
            Value::Domain(ref d) => self.write(&d.as_preserves()?)
        }
    }
}

pub fn bigvarint<W: std::io::Write>(w: &mut W, mut v: u64) -> Result<()> {
    loop {
        if v < (2 << 31) {
            return w.write_all(&(v as u32).to_le_bytes());
        } else {
            w.write_all(&(((v & 0x7fffffff) + (2 << 31)) as u32).to_le_bytes())?;
            v = v >> 31;
        }
    }
}

pub fn varint<W: std::io::Write>(w: &mut W, mut v: u64) -> Result<()> {
    loop {
        if v < 128 {
            return w.write_all(&[v as u8])
        } else {
            w.write_all(&[((v & 0x7f) + 128) as u8])?;
            v = v >> 7;
        }
    }
}