/// This module holds the two dom implementations we use. We distingush between
/// owned and borrowed. The difference being is that the borrowed value will
/// use `&str` as its string type, refferencing the input, while owned will
/// allocate a new String for each value.
///
/// Note that since json strings allow for for escape sequences the borrowed
/// value does not impement zero copy parsing, it does however not allocate
/// new memory for strings.
///
/// This differs notably from serds zero copy implementation as, unlike serde,
/// we do not require prior knowledge sbout string comtent to to take advantage
/// of it.
///
/// ## Usage
/// The value trait is meant to simplify interacting with DOM values, for both
/// creation as well as mutation and inspection.
///
/// Objects can be treated as hashmap's for the most part
/// ```rust
/// use simd_json::{OwnedValue as Value, Value as ValueTrait, ValueBuilder, MutableValue};
/// let mut v = Value::object();
/// v.insert("key", 42);
/// assert_eq!(v.get("key").unwrap(), &42);
/// assert_eq!(v["key"], &42);
/// assert_eq!(v.remove("key").unwrap().unwrap(), 42);
/// assert_eq!(v.get("key"), None);
/// ```
///
/// Arrays can be treated as vectors for the most part
///
/// ```rust
/// use simd_json::{OwnedValue as Value, Value as ValueTrait, ValueBuilder, MutableValue};
/// let mut v = Value::array();
/// v.push("zero");
/// v.push(1);
/// assert_eq!(v[0], &"zero");
/// assert_eq!(v.get_idx(1).unwrap(), &1);
/// assert_eq!(v.pop().unwrap().unwrap(), 1);
/// assert_eq!(v.pop().unwrap().unwrap(), "zero");
/// assert_eq!(v.pop().unwrap(), None);
/// ```
///
/// Nested changes are also possible:
/// ```rust
/// use simd_json::{OwnedValue as Value, Value as ValueTrait, ValueBuilder, MutableValue};
/// let mut o = Value::object();
/// o.insert("key", Value::array());
/// o["key"].push(Value::object());
/// o["key"][0].insert("other", "value");
/// assert_eq!(o.encode(), r#"{"key":[{"other":"value"}]}"#);
/// ```

/// Borrowed values, using Cow's for strings using in situ parsing strategies wherever possible
pub mod borrowed;
pub(crate) mod generator;
/// Owned, lifetimeless version of the value for times when lifetimes are to be avoided
pub mod owned;
/// Tape implementation
pub mod tape;
pub use self::borrowed::{to_value as to_borrowed_value, Value as BorrowedValue};
pub use self::owned::{to_value as to_owned_value, Value as OwnedValue};
use crate::{Deserializer, Result};
use halfbrown::HashMap;
use std::borrow::Borrow;
use std::convert::TryInto;
use std::fmt;
use std::hash::Hash;
use std::marker::PhantomData;
use tape::{Node, StaticNode};

#[derive(Debug, Clone, Copy, PartialEq)]
/// An access error for `ValueType`
pub enum AccessError {
    /// An access attempt to a Value was made under the
    /// assumption that it is an Object - the Value however
    /// wasn't.
    NotAnObject,
    /// An access attempt to a Value was made under the
    /// assumption that it is an Array - the Value however
    /// wasn't.
    NotAnArray,
}
impl fmt::Display for AccessError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::NotAnArray => write!(f, "The value is not an array"),
            Self::NotAnObject => write!(f, "The value is not an object"),
        }
    }
}
impl std::error::Error for AccessError {}

/// Types of JSON values
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum ValueType {
    /// null
    Null,
    /// a boolean
    Bool,
    /// a signed integer type
    I64,
    /// a unsigned integer type
    U64,
    /// a float type
    F64,
    /// a string type
    String,
    /// an array
    Array,
    /// an object
    Object,
}

use std::ops::{Index, IndexMut};

/// Support of builder methods for traits.
pub trait ValueBuilder:
    Default
    + From<StaticNode>
    + From<i8>
    + From<i16>
    + From<i32>
    + From<i64>
    + From<u8>
    + From<u16>
    + From<u32>
    + From<u64>
    + From<f32>
    + From<f64>
    + From<String>
    + From<bool>
    + From<()>
{
    /// Returns an empty array with a given capacity
    fn array_with_capacity(capacity: usize) -> Self;
    /// Returns an empty object with a given capacity
    fn object_with_capacity(capacity: usize) -> Self;
    /// Returns an empty array
    fn array() -> Self {
        Self::array_with_capacity(0)
    }
    /// Returns an empty object
    fn object() -> Self {
        Self::object_with_capacity(0)
    }
    /// Returns anull value
    fn null() -> Self;
}

/// Mutatability for values
pub trait MutableValue: IndexMut<usize> + Value + Sized {
    /// The type for Objects
    type Key;
    /// Tries to insert into this `Value` as an `Object`.
    /// Will return an `AccessError::NotAnObject` if called
    /// on a `Value` that isn't an object - otherwise will
    /// behave the same as `HashMap::insert`
    #[inline]
    fn insert<K, V>(&mut self, k: K, v: V) -> std::result::Result<Option<Self>, AccessError>
    where
        K: Into<<Self as MutableValue>::Key>,
        V: Into<Self>,
        <Self as MutableValue>::Key: Hash + Eq,
    {
        self.as_object_mut()
            .ok_or(AccessError::NotAnObject)
            .map(|o| o.insert(k.into(), v.into()))
    }

    /// Tries to remove from this `Value` as an `Object`.
    /// Will return an `AccessError::NotAnObject` if called
    /// on a `Value` that isn't an object - otherwise will
    /// behave the same as `HashMap::remove`
    #[inline]
    fn remove<Q: ?Sized>(&mut self, k: &Q) -> std::result::Result<Option<Self>, AccessError>
    where
        <Self as MutableValue>::Key: Borrow<Q> + Hash + Eq,
        Q: Hash + Eq,
    {
        self.as_object_mut()
            .ok_or(AccessError::NotAnObject)
            .map(|o| o.remove(k))
    }

    /// Tries to push to this `Value` as an `Array.
    /// Will return an `AccessError::NotAnArray` if called
    /// on a `Value` that isn't an `Array` - otherwise will
    /// behave the same as `Vec::push`
    #[inline]
    fn push<V>(&mut self, v: V) -> std::result::Result<(), AccessError>
    where
        V: Into<Self>,
    {
        self.as_array_mut()
            .ok_or(AccessError::NotAnArray)
            .map(|o| o.push(v.into()))
    }

    /// Tries to pop from this `Value` as an `Array.
    /// Will return an `AccessError::NotAnArray` if called
    /// on a `Value` that isn't an `Array` - otherwise will
    /// behave the same as `Vec::pop`
    #[inline]
    fn pop(&mut self) -> std::result::Result<Option<Self>, AccessError> {
        self.as_array_mut()
            .ok_or(AccessError::NotAnArray)
            .map(Vec::pop)
    }
    /// Same as `get` but returns a mutable ref instead
    //    fn get_amut(&mut self, k: &str) -> Option<&mut Self>;
    fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut Self>
    where
        <Self as MutableValue>::Key: Borrow<Q> + Hash + Eq,
        Q: Hash + Eq,
    {
        self.as_object_mut().and_then(|m| m.get_mut(&k))
    }

    /// Same as `get_idx` but returns a mutable ref instead
    #[inline]
    fn get_idx_mut(&mut self, i: usize) -> Option<&mut Self> {
        self.as_array_mut().and_then(|a| a.get_mut(i))
    }
    /// Tries to represent the value as an array and returns a mutable refference to it
    fn as_array_mut(&mut self) -> Option<&mut Vec<Self>>;
    /// Tries to represent the value as an object and returns a mutable refference to it
    fn as_object_mut(&mut self) -> Option<&mut HashMap<<Self as MutableValue>::Key, Self>>;
}
/// The `Value` exposes common interface for values, this allows using both
/// `BorrowedValue` and `OwnedValue` nearly interchangable
pub trait Value:
    Sized
    + Index<usize>
    + PartialEq<i8>
    + PartialEq<i16>
    + PartialEq<i32>
    + PartialEq<i64>
    + PartialEq<i128>
    + PartialEq<u8>
    + PartialEq<u16>
    + PartialEq<u32>
    + PartialEq<u64>
    + PartialEq<u128>
    + PartialEq<f32>
    + PartialEq<f64>
    + PartialEq<String>
    + PartialEq<bool>
    + PartialEq<()>
{
    /// The type for Objects
    type Key;

    /// Gets a ref to a value based on a key, returns `None` if the
    /// current Value isn't an Object or doesn't contain the key
    /// it was asked for.
    #[inline]
    fn get<Q: ?Sized>(&self, k: &Q) -> Option<&Self>
    where
        Self::Key: Borrow<Q> + Hash + Eq,
        Q: Hash + Eq,
    {
        self.as_object().and_then(|a| a.get(k))
    }

    /// Gets a ref to a value based on n index, returns `None` if the
    /// current Value isn't an Array or doesn't contain the index
    /// it was asked for.
    #[inline]
    fn get_idx(&self, i: usize) -> Option<&Self> {
        self.as_array().and_then(|a| a.get(i))
    }

    /// Returns the type of the current Valye
    fn value_type(&self) -> ValueType;

    /// returns true if the current value is null
    fn is_null(&self) -> bool;

    /// Tries to represent the value as a bool
    fn as_bool(&self) -> Option<bool>;
    /// returns true if the current value a bool
    #[inline]
    fn is_bool(&self) -> bool {
        self.as_bool().is_some()
    }

    /// Tries to represent the value as an i128
    #[inline]
    fn as_i128(&self) -> Option<i128> {
        self.as_i64().and_then(|u| u.try_into().ok())
    }
    /// returns true if the current value can be represented as a i128
    #[inline]
    fn is_i128(&self) -> bool {
        self.as_i128().is_some()
    }

    /// Tries to represent the value as an i64
    fn as_i64(&self) -> Option<i64>;
    /// returns true if the current value can be represented as a i64
    #[inline]
    fn is_i64(&self) -> bool {
        self.as_i64().is_some()
    }

    /// Tries to represent the value as an i32
    fn as_i32(&self) -> Option<i32> {
        self.as_i64().and_then(|u| u.try_into().ok())
    }
    /// returns true if the current value can be represented as a i32
    #[inline]
    fn is_i32(&self) -> bool {
        self.as_i32().is_some()
    }

    /// Tries to represent the value as an i16
    #[inline]
    fn as_i16(&self) -> Option<i16> {
        self.as_i64().and_then(|u| u.try_into().ok())
    }
    /// returns true if the current value can be represented as a i16
    #[inline]
    fn is_i16(&self) -> bool {
        self.as_i16().is_some()
    }

    /// Tries to represent the value as an i8
    #[inline]
    fn as_i8(&self) -> Option<i8> {
        self.as_i64().and_then(|u| u.try_into().ok())
    }
    /// returns true if the current value can be represented as a i8
    #[inline]
    fn is_i8(&self) -> bool {
        self.as_i8().is_some()
    }

    /// Tries to represent the value as an u128
    #[inline]
    fn as_u128(&self) -> Option<u128> {
        self.as_u64().and_then(|u| u.try_into().ok())
    }
    /// returns true if the current value can be represented as a u128
    #[inline]
    fn is_u128(&self) -> bool {
        self.as_u128().is_some()
    }

    /// Tries to represent the value as an u64
    fn as_u64(&self) -> Option<u64>;

    /// returns true if the current value can be represented as a u64
    #[inline]
    fn is_u64(&self) -> bool {
        self.as_u64().is_some()
    }

    /// Tries to represent the value as an usize
    #[inline]
    fn as_usize(&self) -> Option<usize> {
        self.as_u64().and_then(|u| u.try_into().ok())
    }
    /// returns true if the current value can be represented as a usize
    #[inline]
    fn is_usize(&self) -> bool {
        self.as_usize().is_some()
    }

    /// Tries to represent the value as an u32
    #[inline]
    fn as_u32(&self) -> Option<u32> {
        self.as_u64().and_then(|u| u.try_into().ok())
    }
    /// returns true if the current value can be represented as a u32
    #[inline]
    fn is_u32(&self) -> bool {
        self.as_u32().is_some()
    }

    /// Tries to represent the value as an u16
    #[inline]
    fn as_u16(&self) -> Option<u16> {
        self.as_u64().and_then(|u| u.try_into().ok())
    }
    /// returns true if the current value can be represented as a u16
    #[inline]
    fn is_u16(&self) -> bool {
        self.as_u16().is_some()
    }

    /// Tries to represent the value as an u8
    fn as_u8(&self) -> Option<u8> {
        self.as_u64().and_then(|u| u.try_into().ok())
    }
    /// returns true if the current value can be represented as a u8
    #[inline]
    fn is_u8(&self) -> bool {
        self.as_u8().is_some()
    }

    /// Tries to represent the value as a f64
    fn as_f64(&self) -> Option<f64>;
    /// returns true if the current value can be represented as a f64
    #[inline]
    fn is_f64(&self) -> bool {
        self.as_f64().is_some()
    }
    /// Casts the current value to a f64 if possible, this will turn integer
    /// values into floats.
    fn cast_f64(&self) -> Option<f64>;
    /// returns true if the current value can be cast into a f64
    #[inline]
    fn is_f64_castable(&self) -> bool {
        self.cast_f64().is_some()
    }

    /// Tries to represent the value as a f32
    #[allow(clippy::cast_possible_truncation)]
    #[inline]
    fn as_f32(&self) -> Option<f32> {
        self.as_f64().and_then(|u| {
            if u <= f64::from(std::f32::MAX) && u >= f64::from(std::f32::MIN) {
                // Since we check above
                Some(u as f32)
            } else {
                None
            }
        })
    }
    /// returns true if the current value can be represented as a f64
    #[inline]
    fn is_f32(&self) -> bool {
        self.as_f32().is_some()
    }

    /// Tries to represent the value as a &str
    fn as_str(&self) -> Option<&str>;
    /// returns true if the current value can be represented as a str
    #[inline]
    fn is_str(&self) -> bool {
        self.as_str().is_some()
    }

    /// Tries to represent the value as an array and returns a refference to it
    fn as_array(&self) -> Option<&Vec<Self>>;

    /// returns true if the current value can be represented as an array
    #[inline]
    fn is_array(&self) -> bool {
        self.as_array().is_some()
    }

    /// Tries to represent the value as an object and returns a refference to it
    fn as_object(&self) -> Option<&HashMap<Self::Key, Self>>;

    /// returns true if the current value can be represented as an object
    #[inline]
    fn is_object(&self) -> bool {
        self.as_object().is_some()
    }
}

/// Parses a slice of butes into a Value dom. This function will
/// rewrite the slice to de-escape strings.
/// As we reference parts of the input slice the resulting dom
/// has the dame lifetime as the slice it was created from.
pub fn deserialize<'de, Value, Key>(s: &'de mut [u8]) -> Result<Value>
where
    Value: ValueBuilder + From<&'de str> + From<Vec<Value>> + From<HashMap<Key, Value>> + 'de,
    Key: Hash + Eq + From<&'de str>,
{
    match Deserializer::from_slice(s) {
        Ok(de) => Ok(ValueDeserializer::from_deserializer(de).parse()),
        Err(e) => Err(e),
    }
}
struct ValueDeserializer<'de, Value, Key>
where
    Value: ValueBuilder + From<&'de str> + From<Vec<Value>> + From<HashMap<Key, Value>> + 'de,
    Key: Hash + Eq + From<&'de str>,
{
    de: Deserializer<'de>,
    _marker: PhantomData<(Value, Key)>,
}

impl<'de, Value, Key> ValueDeserializer<'de, Value, Key>
where
    Value: ValueBuilder + From<&'de str> + From<Vec<Value>> + From<HashMap<Key, Value>> + 'de,
    Key: Hash + Eq + From<&'de str>,
{
    pub fn from_deserializer(de: Deserializer<'de>) -> Self {
        Self {
            de,
            _marker: PhantomData::default(),
        }
    }

    #[cfg_attr(not(feature = "no-inline"), inline(always))]
    pub fn parse(&mut self) -> Value {
        match self.de.next_() {
            Node::Static(s) => Value::from(s),
            Node::String(s) => Value::from(s),
            Node::Array(len, _) => self.parse_array(len),
            Node::Object(len, _) => self.parse_map(len),
        }
    }

    #[cfg_attr(not(feature = "no-inline"), inline(always))]
    fn parse_array(&mut self, len: usize) -> Value {
        // Rust doens't optimize the normal loop away here
        // so we write our own avoiding the lenght
        // checks during push
        let mut res = Vec::with_capacity(len);
        unsafe {
            res.set_len(len);
            for i in 0..len {
                std::ptr::write(res.get_unchecked_mut(i), self.parse());
            }
        }
        Value::from(res)
    }

    #[cfg_attr(not(feature = "no-inline"), inline(always))]
    fn parse_map(&mut self, len: usize) -> Value {
        let mut res: HashMap<Key, Value> = HashMap::with_capacity(len);

        // Since we checked if it's empty we know that we at least have one
        // element so we eat this
        for _ in 0..len {
            if let Node::String(key) = self.de.next_() {
                res.insert_nocheck(key.into(), self.parse());
            } else {
                unreachable!()
            }
        }
        Value::from(res)
    }
}