use std::hash::{Hash,Hasher};
use std::cmp::{Ordering};
use num::bigint::BigInt;
use std::rc::Rc;
use std::vec::Vec;
use std::string::String;
use std::collections::BTreeSet;
use std::collections::BTreeMap;
use std::ops::Index;
use std::ops::IndexMut;
use num::traits::cast::ToPrimitive;

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

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

/// 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 = (Rc<AValue>, Vec<AValue>);

pub type Set = BTreeSet<AValue>;

pub type Dictionary = BTreeMap<AValue, AValue>;

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.1.eq(&other.1)
    }
}

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.1.cmp(&other.1)
    }
}

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

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

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

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

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

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

impl std::fmt::Debug for Value {
    // 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 std::fmt::Debug for AValue {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        for ann in &self.0 {
            write!(f, "@{:?} ", ann)?;
        }
        self.1.fmt(f)
    }
}

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

impl AValue {
    pub fn rc(self) -> Rc<Self> {
        Rc::new(self)
    }

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

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

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

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

impl Value {
    pub fn wrap(self) -> AValue {
        AValue(Vec::new(), 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 {
        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: &Rc<AValue>, fields: Vec<AValue>) -> Value {
        Value::Record((Rc::clone(label), fields))
    }

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

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

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

    pub fn simple_record(label: &str, fields: Vec<AValue>) -> Value {
        Value::record(&Rc::new(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<AValue>> {
        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<AValue>> {
        if let Value::Sequence(ref s) = *self {
            Some(s)
        } else {
            None
        }
    }

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

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

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

impl Index<usize> for Value {
    type Output = AValue;

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

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

impl Index<&AValue> for Value {
    type Output = AValue;

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

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(&buf[..], None).next()
            .or(Err(serde::de::Error::custom("Internal error")))
    }
}