hash-value 1.0.1

use std::{collections::BTreeMap, fmt::Display};

use serde::{
    ser::{Impossible, SerializeMap, SerializeSeq},
    Serialize, Serializer,
};

use crate::{Error, Result, Value};

impl Serialize for Value {
    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
    where
        S: serde::Serializer,
    {
        match self {
            Value::Array(elements) => {
                let mut seq = serializer.serialize_seq(Some(elements.len()))?;
                for element in elements {
                    seq.serialize_element(element)?;
                }
                seq.end()
            }
            Value::Object(object) => {
                let mut map = serializer.serialize_map(Some(object.len()))?;
                for (key, value) in object.iter() {
                    map.serialize_entry(key, value)?;
                }
                map.end()
            }
            Value::Bool(bool) => serializer.serialize_bool(*bool),
            Value::Unsigned(i) => serializer.serialize_u64(*i),
            Value::Signed(i) => serializer.serialize_i64(*i),
            Value::Float(f) => serializer.serialize_f64(*f),
            Value::String(str) => serializer.serialize_str(str),
            Value::Null => serializer.serialize_none(),
        }
    }
}

pub struct ValueSerializer;

impl Serializer for ValueSerializer {
    type Ok = Value;

    type Error = Error;

    type SerializeSeq = SerializeVecValue;
    type SerializeTuple = SerializeVecValue;
    type SerializeTupleStruct = SerializeVecValue;
    type SerializeTupleVariant = SerializeTupleVariantValue;
    type SerializeMap = SerializeMapValue;
    type SerializeStruct = SerializeMapValue;
    type SerializeStructVariant = SerializeStructVariantValue;

    #[inline]
    fn serialize_bool(self, value: bool) -> Result<Value> {
        Ok(Value::Bool(value))
    }

    #[inline]
    fn serialize_i8(self, value: i8) -> Result<Value> {
        self.serialize_i64(value as i64)
    }

    #[inline]
    fn serialize_i16(self, value: i16) -> Result<Value> {
        self.serialize_i64(value as i64)
    }

    #[inline]
    fn serialize_i32(self, value: i32) -> Result<Value> {
        self.serialize_i64(value as i64)
    }

    fn serialize_i64(self, value: i64) -> Result<Value> {
        Ok(Value::Signed(value))
    }

    fn serialize_i128(self, value: i128) -> Result<Value> {
        if let Ok(value) = u64::try_from(value) {
            Ok(Value::Unsigned(value))
        } else if let Ok(value) = i64::try_from(value) {
            Ok(Value::Signed(value))
        } else {
            Err(<Error as serde::ser::Error>::custom(format!(
                "{value} is out of range"
            )))
        }
    }

    fn serialize_u8(self, value: u8) -> Result<Value> {
        self.serialize_u64(value as u64)
    }

    fn serialize_u16(self, value: u16) -> Result<Value> {
        self.serialize_u64(value as u64)
    }

    fn serialize_u32(self, value: u32) -> Result<Value> {
        self.serialize_u64(value as u64)
    }

    fn serialize_u64(self, value: u64) -> Result<Value> {
        Ok(Value::Unsigned(value))
    }

    fn serialize_u128(self, value: u128) -> Result<Value> {
        if let Ok(value) = u64::try_from(value) {
            Ok(Value::Unsigned(value))
        } else {
            Err(<Error as serde::ser::Error>::custom(format!(
                "{value} is out of range"
            )))
        }
    }

    fn serialize_f32(self, float: f32) -> Result<Value> {
        Ok(Value::from(float))
    }

    fn serialize_f64(self, float: f64) -> Result<Value> {
        Ok(Value::from(float))
    }

    fn serialize_char(self, value: char) -> Result<Value> {
        let mut s = String::with_capacity(1);
        s.push(value);
        Ok(Value::from(s))
    }

    fn serialize_str(self, value: &str) -> Result<Value> {
        Ok(Value::String(value.to_owned()))
    }

    fn serialize_bytes(self, value: &[u8]) -> Result<Value> {
        let vec = value.iter().map(|&b| Value::Unsigned(b as u64)).collect();
        Ok(Value::Array(vec))
    }

    fn serialize_unit(self) -> Result<Value> {
        Ok(Value::Null)
    }

    fn serialize_unit_struct(self, _name: &'static str) -> Result<Value> {
        self.serialize_unit()
    }

    fn serialize_unit_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
    ) -> Result<Value> {
        self.serialize_str(variant)
    }

    fn serialize_newtype_struct<T>(self, _name: &'static str, value: &T) -> Result<Value>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(self)
    }

    fn serialize_newtype_variant<T>(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
        value: &T,
    ) -> Result<Value>
    where
        T: ?Sized + Serialize,
    {
        let mut values = BTreeMap::new();
        values.insert(String::from(variant), to_value(value)?);
        Ok(Value::Object(values))
    }

    fn serialize_none(self) -> Result<Value> {
        self.serialize_unit()
    }

    fn serialize_some<T>(self, value: &T) -> Result<Value>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(self)
    }

    fn serialize_seq(self, len: Option<usize>) -> Result<Self::SerializeSeq> {
        Ok(SerializeVecValue {
            vec: Vec::with_capacity(len.unwrap_or(0)),
        })
    }

    fn serialize_tuple(self, len: usize) -> Result<Self::SerializeTuple> {
        self.serialize_seq(Some(len))
    }

    fn serialize_tuple_struct(
        self,
        _name: &'static str,
        len: usize,
    ) -> Result<Self::SerializeTupleStruct> {
        self.serialize_seq(Some(len))
    }

    fn serialize_tuple_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
        len: usize,
    ) -> Result<Self::SerializeTupleVariant> {
        Ok(SerializeTupleVariantValue {
            name: String::from(variant),
            vec: Vec::with_capacity(len),
        })
    }

    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
        Ok(SerializeMapValue {
            map: BTreeMap::new(),
            next_key: None,
        })
    }

    fn serialize_struct(self, _name: &'static str, len: usize) -> Result<Self::SerializeStruct> {
        self.serialize_map(Some(len))
    }

    fn serialize_struct_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeStructVariant> {
        Ok(SerializeStructVariantValue {
            name: String::from(variant),
            map: BTreeMap::new(),
        })
    }

    fn collect_str<T>(self, value: &T) -> Result<Value>
    where
        T: ?Sized + Display,
    {
        Ok(Value::String(value.to_string()))
    }
}

pub struct SerializeVecValue {
    vec: Vec<Value>,
}

pub struct SerializeTupleVariantValue {
    name: String,
    vec: Vec<Value>,
}

pub struct SerializeMapValue {
    map: BTreeMap<String, Value>,
    next_key: Option<String>,
}

pub struct SerializeStructVariantValue {
    name: String,
    map: BTreeMap<String, Value>,
}

impl serde::ser::SerializeSeq for SerializeVecValue {
    type Ok = Value;
    type Error = Error;

    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        self.vec.push(to_value(value)?);
        Ok(())
    }

    fn end(self) -> Result<Value> {
        Ok(Value::Array(self.vec))
    }
}

impl serde::ser::SerializeTuple for SerializeVecValue {
    type Ok = Value;
    type Error = Error;

    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        serde::ser::SerializeSeq::serialize_element(self, value)
    }

    fn end(self) -> Result<Value> {
        serde::ser::SerializeSeq::end(self)
    }
}

impl serde::ser::SerializeTupleStruct for SerializeVecValue {
    type Ok = Value;
    type Error = Error;

    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        serde::ser::SerializeSeq::serialize_element(self, value)
    }

    fn end(self) -> Result<Value> {
        serde::ser::SerializeSeq::end(self)
    }
}

impl serde::ser::SerializeTupleVariant for SerializeTupleVariantValue {
    type Ok = Value;
    type Error = Error;

    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        self.vec.push(to_value(value)?);
        Ok(())
    }

    fn end(self) -> Result<Value> {
        let mut object = BTreeMap::new();
        object.insert(self.name, Value::Array(self.vec));
        Ok(Value::Object(object))
    }
}

impl serde::ser::SerializeMap for SerializeMapValue {
    type Ok = Value;
    type Error = Error;

    fn serialize_key<T>(&mut self, key: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        self.next_key = Some(key.serialize(MapKeyValueSerializer)?);
        Ok(())
    }

    fn serialize_value<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        let key = self
            .next_key
            .take()
            .expect("serialize_value called before serialize_key");
        self.map.insert(key, to_value(value)?);
        Ok(())
    }

    fn end(self) -> Result<Value> {
        Ok(Value::Object(self.map))
    }
}

struct MapKeyValueSerializer;

fn key_must_be_a_string() -> Error {
    <Error as serde::ser::Error>::custom("key must be a string")
}

fn float_key_must_be_finite() -> Error {
    <Error as serde::ser::Error>::custom("float key must be finite")
}

impl serde::Serializer for MapKeyValueSerializer {
    type Ok = String;
    type Error = Error;

    type SerializeSeq = Impossible<String, Error>;
    type SerializeTuple = Impossible<String, Error>;
    type SerializeTupleStruct = Impossible<String, Error>;
    type SerializeTupleVariant = Impossible<String, Error>;
    type SerializeMap = Impossible<String, Error>;
    type SerializeStruct = Impossible<String, Error>;
    type SerializeStructVariant = Impossible<String, Error>;

    #[inline]
    fn serialize_unit_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
    ) -> Result<String> {
        Ok(variant.to_owned())
    }

    #[inline]
    fn serialize_newtype_struct<T>(self, _name: &'static str, value: &T) -> Result<String>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(self)
    }

    fn serialize_bool(self, value: bool) -> Result<String> {
        Ok(value.to_string())
    }

    fn serialize_i8(self, value: i8) -> Result<String> {
        Ok(value.to_string())
    }

    fn serialize_i16(self, value: i16) -> Result<String> {
        Ok(value.to_string())
    }

    fn serialize_i32(self, value: i32) -> Result<String> {
        Ok(value.to_string())
    }

    fn serialize_i64(self, value: i64) -> Result<String> {
        Ok(value.to_string())
    }

    fn serialize_u8(self, value: u8) -> Result<String> {
        Ok(value.to_string())
    }

    fn serialize_u16(self, value: u16) -> Result<String> {
        Ok(value.to_string())
    }

    fn serialize_u32(self, value: u32) -> Result<String> {
        Ok(value.to_string())
    }

    fn serialize_u64(self, value: u64) -> Result<String> {
        Ok(value.to_string())
    }

    fn serialize_f32(self, value: f32) -> Result<String> {
        if value.is_finite() {
            Ok(value.to_string())
        } else {
            Err(float_key_must_be_finite())
        }
    }

    fn serialize_f64(self, value: f64) -> Result<String> {
        if value.is_finite() {
            Ok(value.to_string())
        } else {
            Err(float_key_must_be_finite())
        }
    }

    #[inline]
    fn serialize_char(self, value: char) -> Result<String> {
        Ok({
            let mut s = String::new();
            s.push(value);
            s
        })
    }

    #[inline]
    fn serialize_str(self, value: &str) -> Result<String> {
        Ok(value.to_owned())
    }

    fn serialize_bytes(self, _value: &[u8]) -> Result<String> {
        Err(key_must_be_a_string())
    }

    fn serialize_unit(self) -> Result<String> {
        Err(key_must_be_a_string())
    }

    fn serialize_unit_struct(self, _name: &'static str) -> Result<String> {
        Err(key_must_be_a_string())
    }

    fn serialize_newtype_variant<T>(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _value: &T,
    ) -> Result<String>
    where
        T: ?Sized + Serialize,
    {
        Err(key_must_be_a_string())
    }

    fn serialize_none(self) -> Result<String> {
        Err(key_must_be_a_string())
    }

    fn serialize_some<T>(self, _value: &T) -> Result<String>
    where
        T: ?Sized + Serialize,
    {
        Err(key_must_be_a_string())
    }

    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq> {
        Err(key_must_be_a_string())
    }

    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple> {
        Err(key_must_be_a_string())
    }

    fn serialize_tuple_struct(
        self,
        _name: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleStruct> {
        Err(key_must_be_a_string())
    }

    fn serialize_tuple_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleVariant> {
        Err(key_must_be_a_string())
    }

    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
        Err(key_must_be_a_string())
    }

    fn serialize_struct(self, _name: &'static str, _len: usize) -> Result<Self::SerializeStruct> {
        Err(key_must_be_a_string())
    }

    fn serialize_struct_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeStructVariant> {
        Err(key_must_be_a_string())
    }

    fn collect_str<T>(self, value: &T) -> Result<String>
    where
        T: ?Sized + Display,
    {
        Ok(value.to_string())
    }
}

impl serde::ser::SerializeStruct for SerializeMapValue {
    type Ok = Value;
    type Error = Error;

    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        serde::ser::SerializeMap::serialize_entry(self, key, value)
    }

    fn end(self) -> Result<Value> {
        serde::ser::SerializeMap::end(self)
    }
}

impl serde::ser::SerializeStructVariant for SerializeStructVariantValue {
    type Ok = Value;
    type Error = Error;

    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        self.map.insert(String::from(key), to_value(value)?);
        Ok(())
    }

    fn end(self) -> Result<Value> {
        let mut object = BTreeMap::new();
        object.insert(self.name, Value::Object(self.map));
        Ok(Value::Object(object))
    }
}

/// Transform any [`Serialize`] value to a [`Value`].
pub fn to_value<T>(input: T) -> Result<Value>
where
    T: Serialize,
{
    input.serialize(ValueSerializer)
}

#[test]
fn serialize_to_value() {
    use crate::test::{test_struct, test_value};
    let my_struct = test_struct();
    let serialized_result = to_value(my_struct);
    assert!(serialized_result.is_ok());
    assert_eq!(serialized_result.unwrap(), test_value());
}