use std::hash::{Hash,Hasher};
use std::cmp::{Ordering};
use std::fmt::Debug;
use num::bigint::BigInt;
use std::vec::Vec;
use std::string::String;
use std::collections::BTreeSet as Set;
use std::collections::BTreeMap as Map;
use std::ops::Deref;
use std::ops::Index;
use std::ops::IndexMut;
use num::traits::cast::ToPrimitive;

pub trait NestedValue: Sized + Debug + Clone + Eq + Hash + Ord {
    type BoxType: Sized + Debug + Clone + Eq + Hash + Ord + Deref<Target=Self>;

    fn wrap(v: Value<Self>) -> Self;
    fn wrap_ann(anns: Vec<Self>, v: Value<Self>) -> Self;

    fn boxwrap(self) -> Self::BoxType;
    fn boxunwrap(b: &Self::BoxType) -> &Self;

    fn annotations(&self) -> &Vec<Self>;
    fn annotations_mut(&mut self) -> &mut Vec<Self>;

    fn value(&self) -> &Value<Self>;
    fn value_mut(&mut self) -> &mut Value<Self>;
    fn value_owned(self) -> Value<Self>;

    fn debug_fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        for ann in self.annotations() {
            write!(f, "@{:?} ", ann)?;
        }
        self.value().fmt(f)
    }

    fn copy_via<M: NestedValue>(&self) -> M {
        M::wrap_ann(self.annotations().iter().map(|a| a.copy_via()).collect(),
                    self.value().copy_via())
    }
}

/// The `Value`s from the specification.
#[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub enum Value<N> where N: NestedValue {
    Boolean(bool),
    Float(Float),
    Double(Double),
    SignedInteger(BigInt),
    String(String),
    ByteString(Vec<u8>),
    Symbol(String),
    Record(Record<N>),
    Sequence(Vec<N>),
    Set(Set<N>),
    Dictionary(Map<N, N>),
}

/// An possibly-annotated Value, with annotations (themselves
/// possibly-annotated) in order of appearance.
#[derive(Clone)]
pub struct AValue(pub Vec<AValue>, pub Value<AValue>);

impl NestedValue for AValue {
    type BoxType = Box<Self>;

    fn wrap(v: Value<Self>) -> Self {
        Self::wrap_ann(Vec::new(), v)
    }

    fn wrap_ann(anns: Vec<Self>, v: Value<Self>) -> Self {
        AValue(anns, v)
    }

    fn boxwrap(self) -> Self::BoxType {
        Box::new(self)
    }

    fn boxunwrap(b: &Self::BoxType) -> &Self {
        &**b
    }

    fn annotations(&self) -> &Vec<Self> {
        &self.0
    }

    fn annotations_mut(&mut self) -> &mut Vec<Self> {
        &mut self.0
    }

    fn value(&self) -> &Value<Self> {
        &self.1
    }

    fn value_mut(&mut self) -> &mut Value<Self> {
        &mut self.1
    }

    fn value_owned(self) -> Value<Self> {
        self.1
    }
}

/// Single-precision IEEE 754 Value
#[derive(Clone, Debug)]
pub struct Float(pub f32);

/// Double-precision IEEE 754 Value
#[derive(Clone, Debug)]
pub struct Double(pub f64);

/// A Record `Value`
pub type Record<N> = (<N as NestedValue>::BoxType, Vec<N>);

impl From<f32> for Float {
    fn from(v: f32) -> Self {
        Float(v)
    }
}

impl From<Float> for f32 {
    fn from(v: Float) -> Self {
        v.0
    }
}

impl Hash for Float {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.0.to_bits().hash(state);
    }
}

impl PartialEq for Float {
    fn eq(&self, other: &Self) -> bool {
        self.0.to_bits() == other.0.to_bits()
    }
}

impl Ord for Float {
    fn cmp(&self, other: &Self) -> Ordering {
        let mut a: u32 = self.0.to_bits();
        let mut b: u32 = other.0.to_bits();
        if a & 0x80000000 != 0 { a ^= 0x7fffffff; }
        if b & 0x80000000 != 0 { b ^= 0x7fffffff; }
        (a as i32).cmp(&(b as i32))
    }
}

impl PartialOrd for Float {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Eq for Float {}

impl From<f64> for Double {
    fn from(v: f64) -> Self {
        Double(v)
    }
}

impl From<Double> for f64 {
    fn from(v: Double) -> Self {
        v.0
    }
}

impl Hash for Double {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.0.to_bits().hash(state);
    }
}

impl PartialEq for Double {
    fn eq(&self, other: &Self) -> bool {
        return self.0.to_bits() == other.0.to_bits();
    }
}

impl Ord for Double {
    fn cmp(&self, other: &Self) -> Ordering {
        let mut a: u64 = self.0.to_bits();
        let mut b: u64 = other.0.to_bits();
        if a & 0x8000000000000000 != 0 { a ^= 0x7fffffffffffffff; }
        if b & 0x8000000000000000 != 0 { b ^= 0x7fffffffffffffff; }
        (a as i64).cmp(&(b as i64))
    }
}

impl PartialOrd for Double {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Eq for Double {}

impl PartialEq for AValue {
    fn eq(&self, other: &Self) -> bool {
        self.value().eq(other.value())
    }
}

impl Eq for AValue {}

impl Hash for AValue {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.1.hash(state);
    }
}

impl PartialOrd for AValue {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for AValue {
    fn cmp(&self, other: &Self) -> Ordering {
        self.value().cmp(&other.value())
    }
}

impl Debug for AValue {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        self.debug_fmt(f)
    }
}

impl<N: NestedValue> From<bool> for Value<N> { fn from(v: bool) -> Self { Value::Boolean(v) } }

impl<N: NestedValue> From<f32> for Value<N> { fn from(v: f32) -> Self { Value::Float(Float::from(v)) } }
impl<N: NestedValue> From<f64> for Value<N> { fn from(v: f64) -> Self { Value::Double(Double::from(v)) } }

impl<N: NestedValue> From<u8> for Value<N> { fn from(v: u8) -> Self { Value::SignedInteger(BigInt::from(v)) } }
impl<N: NestedValue> From<i8> for Value<N> { fn from(v: i8) -> Self { Value::SignedInteger(BigInt::from(v)) } }
impl<N: NestedValue> From<u16> for Value<N> { fn from(v: u16) -> Self { Value::SignedInteger(BigInt::from(v)) } }
impl<N: NestedValue> From<i16> for Value<N> { fn from(v: i16) -> Self { Value::SignedInteger(BigInt::from(v)) } }
impl<N: NestedValue> From<u32> for Value<N> { fn from(v: u32) -> Self { Value::SignedInteger(BigInt::from(v)) } }
impl<N: NestedValue> From<i32> for Value<N> { fn from(v: i32) -> Self { Value::SignedInteger(BigInt::from(v)) } }
impl<N: NestedValue> From<u64> for Value<N> { fn from(v: u64) -> Self { Value::SignedInteger(BigInt::from(v)) } }
impl<N: NestedValue> From<i64> for Value<N> { fn from(v: i64) -> Self { Value::SignedInteger(BigInt::from(v)) } }
impl<N: NestedValue> From<u128> for Value<N> { fn from(v: u128) -> Self { Value::SignedInteger(BigInt::from(v)) } }
impl<N: NestedValue> From<i128> for Value<N> { fn from(v: i128) -> Self { Value::SignedInteger(BigInt::from(v)) } }
impl<N: NestedValue> From<BigInt> for Value<N> { fn from(v: BigInt) -> Self { Value::SignedInteger(v) } }

impl<N: NestedValue> From<&str> for Value<N> { fn from(v: &str) -> Self { Value::String(String::from(v)) } }
impl<N: NestedValue> From<String> for Value<N> { fn from(v: String) -> Self { Value::String(v) } }

impl<N: NestedValue> From<&[u8]> for Value<N> { fn from(v: &[u8]) -> Self { Value::ByteString(Vec::from(v)) } }
impl<N: NestedValue> From<Vec<u8>> for Value<N> { fn from(v: Vec<u8>) -> Self { Value::ByteString(v) } }

impl<N: NestedValue> From<Vec<N>> for Value<N> { fn from(v: Vec<N>) -> Self { Value::Sequence(v) } }
impl<N: NestedValue> From<Set<N>> for Value<N> { fn from(v: Set<N>) -> Self { Value::Set(v) } }
impl<N: NestedValue> From<Map<N, N>> for Value<N> { fn from(v: Map<N, N>) -> Self { Value::Dictionary(v) } }

impl<N: NestedValue> Debug for Value<N> {
    // Not *quite* a formatter for the Preserves text syntax, since it
    // doesn't escape strings/symbols properly.
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Value::Boolean(false) => f.write_str("#false"),
            Value::Boolean(true) => f.write_str("#true"),
            Value::Float(Float(v)) => write!(f, "{:?}f", v),
            Value::Double(Double(v)) => write!(f, "{:?}", v),
            Value::SignedInteger(v) => write!(f, "{}", v),
            Value::String(ref v) => write!(f, "{:?}", v), // TODO: proper escaping!
            Value::ByteString(ref v) => {
                f.write_str("#hex{")?;
                for b in v { write!(f, "{:02x}", b)? }
                f.write_str("}")
            }
            Value::Symbol(ref v) => {
                // TODO: proper escaping!
                if v.len() == 0 {
                    f.write_str("||")
                } else {
                    write!(f, "{}", v)
                }
            }
            Value::Record((ref l, ref fs)) => {
                f.write_str("<")?;
                l.fmt(f)?;
                for v in fs {
                    f.write_str(" ")?;
                    v.fmt(f)?;
                }
                f.write_str(">")
            }
            Value::Sequence(ref v) => v.fmt(f),
            Value::Set(ref v) => {
                f.write_str("#set")?;
                f.debug_set().entries(v.iter()).finish()
            }
            Value::Dictionary(ref v) => f.debug_map().entries(v.iter()).finish()
        }
    }
}

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

impl<N: NestedValue> Value<N> {
    pub fn wrap(self) -> N {
        N::wrap(self)
    }

    pub fn is_boolean(&self) -> bool {
        self.as_boolean().is_some()
    }

    pub fn as_boolean(&self) -> Option<bool> {
        if let Value::Boolean(b) = *self {
            Some(b)
        } else {
            None
        }
    }

    pub fn as_boolean_mut(&mut self) -> Option<&mut bool> {
        if let Value::Boolean(ref mut b) = *self {
            Some(b)
        } else {
            None
        }
    }

    pub fn is_float(&self) -> bool {
        self.as_float().is_some()
    }

    pub fn as_float(&self) -> Option<f32> {
        if let Value::Float(Float(f)) = *self {
            Some(f)
        } else {
            None
        }
    }

    pub fn as_float_mut(&mut self) -> Option<&mut f32> {
        if let Value::Float(Float(ref mut f)) = *self {
            Some(f)
        } else {
            None
        }
    }

    pub fn is_double(&self) -> bool {
        self.as_double().is_some()
    }

    pub fn as_double(&self) -> Option<f64> {
        if let Value::Double(Double(f)) = *self {
            Some(f)
        } else {
            None
        }
    }

    pub fn as_double_mut(&mut self) -> Option<&mut f64> {
        if let Value::Double(Double(ref mut f)) = *self {
            Some(f)
        } else {
            None
        }
    }

    pub fn is_signedinteger(&self) -> bool {
        self.as_signedinteger().is_some()
    }

    pub fn as_signedinteger(&self) -> Option<&BigInt> {
        if let Value::SignedInteger(ref i) = *self {
            Some(i)
        } else {
            None
        }
    }

    pub fn as_signedinteger_mut(&mut self) -> Option<&mut BigInt> {
        if let Value::SignedInteger(ref mut i) = *self {
            Some(i)
        } else {
            None
        }
    }

    pub fn as_u8(&self) -> Option<u8> { self.as_signedinteger().and_then(|i| i.to_u8()) }
    pub fn as_i8(&self) -> Option<i8> { self.as_signedinteger().and_then(|i| i.to_i8()) }
    pub fn as_u16(&self) -> Option<u16> { self.as_signedinteger().and_then(|i| i.to_u16()) }
    pub fn as_i16(&self) -> Option<i16> { self.as_signedinteger().and_then(|i| i.to_i16()) }
    pub fn as_u32(&self) -> Option<u32> { self.as_signedinteger().and_then(|i| i.to_u32()) }
    pub fn as_i32(&self) -> Option<i32> { self.as_signedinteger().and_then(|i| i.to_i32()) }
    pub fn as_u64(&self) -> Option<u64> { self.as_signedinteger().and_then(|i| i.to_u64()) }
    pub fn as_i64(&self) -> Option<i64> { self.as_signedinteger().and_then(|i| i.to_i64()) }

    pub fn is_string(&self) -> bool {
        self.as_string().is_some()
    }

    pub fn as_string(&self) -> Option<&String> {
        if let Value::String(ref s) = *self {
            Some(s)
        } else {
            None
        }
    }

    pub fn as_string_mut(&mut self) -> Option<&mut String> {
        if let Value::String(ref mut s) = *self {
            Some(s)
        } else {
            None
        }
    }

    pub fn is_bytestring(&self) -> bool {
        self.as_bytestring().is_some()
    }

    pub fn as_bytestring(&self) -> Option<&Vec<u8>> {
        if let Value::ByteString(ref s) = *self {
            Some(s)
        } else {
            None
        }
    }

    pub fn as_bytestring_mut(&mut self) -> Option<&mut Vec<u8>> {
        if let Value::ByteString(ref mut s) = *self {
            Some(s)
        } else {
            None
        }
    }

    pub fn symbol(s: &str) -> Value<N> {
        Value::Symbol(s.to_string())
    }

    pub fn is_symbol(&self) -> bool {
        self.as_symbol().is_some()
    }

    pub fn as_symbol(&self) -> Option<&String> {
        if let Value::Symbol(ref s) = *self {
            Some(s)
        } else {
            None
        }
    }

    pub fn as_symbol_mut(&mut self) -> Option<&mut String> {
        if let Value::Symbol(ref mut s) = *self {
            Some(s)
        } else {
            None
        }
    }

    pub fn record(label: N, fields: Vec<N>) -> Value<N> {
        Value::Record((label.boxwrap(), fields))
    }

    pub fn is_record(&self) -> bool {
        self.as_record().is_some()
    }

    pub fn as_record(&self) -> Option<&Record<N>> {
        if let Value::Record(ref r) = *self {
            Some(r)
        } else {
            None
        }
    }

    pub fn as_record_mut(&mut self) -> Option<&mut Record<N>> {
        if let Value::Record(ref mut r) = *self {
            Some(r)
        } else {
            None
        }
    }

    pub fn simple_record(label: &str, fields: Vec<N>) -> Value<N> {
        Value::record(Value::symbol(label).wrap(), fields)
    }

    pub fn is_simple_record(&self, label: &str, arity: Option<usize>) -> bool {
        self.as_simple_record(label, arity).is_some()
    }

    pub fn as_simple_record(&self, label: &str, arity: Option<usize>) -> Option<&Vec<N>> {
        self.as_record().and_then(|(lp,fs)| {
            match *lp.value() {
                Value::Symbol(ref s) if s == label =>
                    match arity {
                        Some(expected) if fs.len() == expected => Some(fs),
                        Some(_other) => None,
                        None => Some(fs)
                    }
                _ => None
            }
        })
    }

    pub fn is_sequence(&self) -> bool {
        self.as_sequence().is_some()
    }

    pub fn as_sequence(&self) -> Option<&Vec<N>> {
        if let Value::Sequence(ref s) = *self {
            Some(s)
        } else {
            None
        }
    }

    pub fn as_sequence_mut(&mut self) -> Option<&mut Vec<N>> {
        if let Value::Sequence(ref mut s) = *self {
            Some(s)
        } else {
            None
        }
    }

    pub fn is_set(&self) -> bool {
        self.as_set().is_some()
    }

    pub fn as_set(&self) -> Option<&Set<N>> {
        if let Value::Set(ref s) = *self {
            Some(s)
        } else {
            None
        }
    }

    pub fn as_set_mut(&mut self) -> Option<&mut Set<N>> {
        if let Value::Set(ref mut s) = *self {
            Some(s)
        } else {
            None
        }
    }

    pub fn is_dictionary(&self) -> bool {
        self.as_dictionary().is_some()
    }

    pub fn as_dictionary(&self) -> Option<&Map<N, N>> {
        if let Value::Dictionary(ref s) = *self {
            Some(s)
        } else {
            None
        }
    }

    pub fn as_dictionary_mut(&mut self) -> Option<&mut Map<N, N>> {
        if let Value::Dictionary(ref mut s) = *self {
            Some(s)
        } else {
            None
        }
    }

    pub fn copy_via<M: NestedValue>(&self) -> Value<M> {
        match self {
            Value::Boolean(b) => Value::Boolean(*b),
            Value::Float(f) => Value::Float(f.clone()),
            Value::Double(d) => Value::Double(d.clone()),
            Value::SignedInteger(i) => Value::SignedInteger(i.clone()),
            Value::String(ref s) => Value::String(s.clone()),
            Value::ByteString(ref v) => Value::ByteString(v.clone()),
            Value::Symbol(ref v) => Value::String(v.clone()),
            Value::Record((ref l, ref fs)) =>
                Value::Record((N::boxunwrap(l).copy_via::<M>().boxwrap(), fs.iter().map(|a| a.copy_via()).collect())),
            Value::Sequence(ref v) => Value::Sequence(v.iter().map(|a| a.copy_via()).collect()),
            Value::Set(ref v) => Value::Set(v.iter().map(|a| a.copy_via()).collect()),
            Value::Dictionary(ref v) =>
                Value::Dictionary(v.iter().map(|(a,b)| (a.copy_via(), b.copy_via())).collect()),
        }
    }
}

impl<N: NestedValue> Index<usize> for Value<N> {
    type Output = N;

    fn index(&self, i: usize) -> &Self::Output {
        &self.as_sequence().unwrap()[i]
    }
}

impl<N: NestedValue> IndexMut<usize> for Value<N> {
    fn index_mut(&mut self, i: usize) -> &mut Self::Output {
        &mut self.as_sequence_mut().unwrap()[i]
    }
}

impl<N: NestedValue> Index<&N> for Value<N> {
    type Output = N;

    fn index(&self, i: &N) -> &Self::Output {
        &(*self.as_dictionary().unwrap())[i]
    }
}

//---------------------------------------------------------------------------
// This part is a terrible hack

pub static MAGIC: &str = "$____Preserves_Value";

#[derive(serde::Serialize)]
#[serde(rename = "$____Preserves_Value")]
struct ValueWrapper(#[serde(with = "serde_bytes")] Vec<u8>);

struct ValueWrapperVisitor;

impl<'de> serde::de::Visitor<'de> for ValueWrapperVisitor {
    type Value = ValueWrapper;

    fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(formatter, "an encoded value wrapper")
    }

    fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E> where E: serde::de::Error {
        Ok(ValueWrapper(Vec::from(v)))
    }
}

impl<'de> serde::Deserialize<'de> for ValueWrapper {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: serde::Deserializer<'de> {
        deserializer.deserialize_newtype_struct(MAGIC, ValueWrapperVisitor)
    }
}

impl<N: NestedValue> serde::Serialize for Value<N> {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: serde::Serializer {
        let mut buf: Vec<u8> = Vec::new();
        crate::value::Encoder::new(&mut buf, None).write_value(self)
            .or(Err(serde::ser::Error::custom("Internal error")))?;
        ValueWrapper(buf).serialize(serializer)
    }
}

impl serde::Serialize for AValue {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: serde::Serializer {
        let mut buf: Vec<u8> = Vec::new();
        crate::value::Encoder::new(&mut buf, None).write(self)
            .or(Err(serde::ser::Error::custom("Internal error")))?;
        ValueWrapper(buf).serialize(serializer)
    }
}

impl<'de, N: NestedValue> serde::Deserialize<'de> for Value<N> {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: serde::Deserializer<'de> {
        let ValueWrapper(buf) = ValueWrapper::deserialize(deserializer)?;
        let v: N = crate::value::Decoder::new(&mut &buf[..], None).next()
            .or(Err(serde::de::Error::custom("Internal error")))?;
        Ok(v.value_owned())
    }
}

impl<'de> serde::Deserialize<'de> for AValue {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: serde::Deserializer<'de> {
        let ValueWrapper(buf) = ValueWrapper::deserialize(deserializer)?;
        crate::value::Decoder::new(&mut &buf[..], None).next()
            .or(Err(serde::de::Error::custom("Internal error")))
    }
}