use std::collections::HashMap;
use std::fmt::Display;
use crate::value::Value;
use serde::ser::{SerializeMap, SerializeSeq, SerializeStruct, SerializeStructVariant, SerializeTuple, SerializeTupleStruct, SerializeTupleVariant};
use serde::{Serialize, Serializer};
use thiserror::Error;


#[derive(Debug, Error)]
pub enum SerializerError {
    #[error("{0}")]
    Message(String),

    #[error("key must be a string")]
    KeyMustBeAString,
}

impl serde::ser::Error for SerializerError {
    fn custom<T>(msg: T) -> Self
        where T: Display,
    {
        SerializerError::Message(msg.to_string())
    }
}


pub struct ValueSerializer;

impl Serializer for ValueSerializer {
    type Ok = Value;
    type Error = SerializerError;
    type SerializeSeq = SeqSerializer;
    type SerializeTuple = TupleSerializer;
    type SerializeTupleStruct = TupleStructSerializer;
    type SerializeTupleVariant = TupleVariantSerializer<'static>;
    type SerializeMap = MapSerializer;
    type SerializeStruct = StructSerializer;
    type SerializeStructVariant = StructVariantSerializer<'static>;

    fn serialize_bool(self, v: bool) -> Result<Self::Ok, Self::Error> {
        Ok(Value::Bool(v))
    }

    fn serialize_i8(self, v: i8) -> Result<Self::Ok, Self::Error> {
        Ok(v.into())
    }

    fn serialize_i16(self, v: i16) -> Result<Self::Ok, Self::Error> {
        Ok(v.into())
    }

    fn serialize_i32(self, v: i32) -> Result<Self::Ok, Self::Error> {
        Ok(v.into())
    }

    fn serialize_i64(self, v: i64) -> Result<Self::Ok, Self::Error> {
        Ok(v.into())
    }

    fn serialize_u8(self, v: u8) -> Result<Self::Ok, Self::Error> {
        Ok(v.into())
    }

    fn serialize_u16(self, v: u16) -> Result<Self::Ok, Self::Error> {
        Ok(v.into())
    }

    fn serialize_u32(self, v: u32) -> Result<Self::Ok, Self::Error> {
        Ok(v.into())
    }

    fn serialize_u64(self, v: u64) -> Result<Self::Ok, Self::Error> {
        Ok(v.into())
    }

    fn serialize_f32(self, v: f32) -> Result<Self::Ok, Self::Error> {
        Ok(v.into())
    }

    fn serialize_f64(self, v: f64) -> Result<Self::Ok, Self::Error> {
        Ok(v.into())
    }

    fn serialize_char(self, v: char) -> Result<Self::Ok, Self::Error> {
        Ok(v.to_string().into())
    }

    fn serialize_str(self, v: &str) -> Result<Self::Ok, Self::Error> {
        Ok(v.into())
    }

    fn serialize_bytes(self, v: &[u8]) -> Result<Self::Ok, Self::Error> {
        let mut seq = self.serialize_seq(Some(v.len()))?;
        for byte in v {
            seq.serialize_element(byte)?;
        }

        seq.end()
    }

    fn serialize_none(self) -> Result<Self::Ok, Self::Error> {
        Ok(Value::None)
    }

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

    fn serialize_unit(self) -> Result<Self::Ok, Self::Error> {
        Ok(Value::None)
    }

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

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

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

    fn serialize_newtype_variant<T: ?Sized>(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
        value: &T,
    ) -> Result<Self::Ok, Self::Error>
        where
            T: Serialize,
    {
        Ok(Value::Map(HashMap::from([(variant.to_string(), value.serialize(self)?)])))
    }

    fn serialize_seq(self, len: Option<usize>) -> Result<Self::SerializeSeq, Self::Error> {
        Ok(SeqSerializer::new(len))
    }

    fn serialize_tuple(self, len: usize) -> Result<Self::SerializeTuple, Self::Error> {
        Ok(TupleSerializer::new(len))
    }

    fn serialize_tuple_struct(
        self,
        _name: &'static str,
        len: usize,
    ) -> Result<Self::SerializeTupleStruct, Self::Error> {
        Ok(TupleStructSerializer::new(len))
    }

    fn serialize_tuple_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
        len: usize,
    ) -> Result<Self::SerializeTupleVariant, Self::Error> {
        Ok(TupleVariantSerializer::new(variant, len))
    }

    fn serialize_map(self, len: Option<usize>) -> Result<Self::SerializeMap, Self::Error> {
        Ok(MapSerializer::new(len))
    }

    fn serialize_struct(
        self,
        _name: &'static str,
        len: usize,
    ) -> Result<Self::SerializeStruct, Self::Error> {
        Ok(StructSerializer::new(len))
    }

    fn serialize_struct_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
        len: usize,
    ) -> Result<Self::SerializeStructVariant, Self::Error> {
        Ok(StructVariantSerializer::new(variant, len))
    }
}

pub struct SeqSerializer {
    sequence: Vec<Value>,
}

impl SeqSerializer {
    pub fn new(len: Option<usize>) -> Self {
        SeqSerializer {
            sequence: Vec::with_capacity(len.unwrap_or(0)),
        }
    }
}

impl<'a> SerializeSeq for SeqSerializer {
    type Ok = Value;
    type Error = SerializerError;

    fn serialize_element<T: ?Sized>(&mut self, value: &T) -> Result<(), Self::Error>
        where
            T: Serialize,
    {
        self.sequence.push(value.serialize(ValueSerializer)?);
        Ok(())
    }

    fn end(self) -> Result<Self::Ok, Self::Error> {
        Ok(self.sequence.into())
    }
}

pub struct MapSerializer {
    keys: Vec<String>,
    values: Vec<Value>,
}

impl MapSerializer {
    pub fn new(len: Option<usize>) -> Self {
        MapSerializer {
            keys: Vec::with_capacity(len.unwrap_or(0)),
            values: Vec::with_capacity(len.unwrap_or(0)),
        }
    }
}

impl<'a> SerializeMap for MapSerializer {
    type Ok = Value;
    type Error = SerializerError;

    fn serialize_key<T: ?Sized>(&mut self, key: &T) -> Result<(), Self::Error>
        where
            T: Serialize,
    {
        match key.serialize(ValueSerializer)? {
            Value::String(s) => self.keys.push(s),
            _ => return Err(SerializerError::KeyMustBeAString),
        };

        Ok(())
    }

    fn serialize_value<T: ?Sized>(&mut self, value: &T) -> Result<(), Self::Error>
        where
            T: Serialize,
    {
        self.values.push(value.serialize(ValueSerializer)?);
        Ok(())
    }

    fn end(self) -> Result<Self::Ok, Self::Error> {
        let iter = self.keys.into_iter().zip(self.values.into_iter());
        Ok(iter.collect::<HashMap<String, Value>>().into())
    }
}

pub struct TupleSerializer {
    seq_serializer: SeqSerializer,
}

impl TupleSerializer {
    pub fn new(len: usize) -> Self {
        TupleSerializer {
            seq_serializer: SeqSerializer::new(Some(len)),
        }
    }
}

impl<'a> SerializeTuple for TupleSerializer {
    type Ok = Value;
    type Error = SerializerError;

    fn serialize_element<T: ?Sized>(&mut self, value: &T) -> Result<(), SerializerError>
        where
            T: Serialize,
    {
        self.seq_serializer.serialize_element(value)
    }

    fn end(self) -> Result<Self::Ok, Self::Error> {
        self.seq_serializer.end()
    }
}

pub struct TupleStructSerializer {
    seq_serializer: SeqSerializer,
}

impl TupleStructSerializer {
    pub fn new(len: usize) -> Self {
        TupleStructSerializer {
            seq_serializer: SeqSerializer::new(Some(len)),
        }
    }
}

impl<'a> SerializeTupleStruct for TupleStructSerializer {
    type Ok = Value;
    type Error = SerializerError;

    fn serialize_field<T: ?Sized>(&mut self, value: &T) -> Result<(), SerializerError>
        where
            T: Serialize,
    {
        self.seq_serializer.serialize_element(value)
    }

    fn end(self) -> Result<Self::Ok, Self::Error> {
        self.seq_serializer.end()
    }
}

pub struct StructSerializer {
    map_serializer: MapSerializer,
}

impl StructSerializer {
    pub fn new(len: usize) -> Self {
        StructSerializer {
            map_serializer: MapSerializer::new(Some(len)),
        }
    }
}

impl SerializeStruct for StructSerializer {
    type Ok = Value;
    type Error = SerializerError;

    fn serialize_field<T: ?Sized>(
        &mut self,
        key: &'static str,
        value: &T,
    ) -> Result<(), Self::Error>
        where
            T: Serialize,
    {
        self.map_serializer.serialize_entry(key, value)
    }

    fn end(self) -> Result<Self::Ok, Self::Error> {
        self.map_serializer.end()
    }
}

pub struct StructVariantSerializer<'de> {
    name: &'de str,
    map_serializer: StructSerializer,
}

impl<'de> StructVariantSerializer<'de> {
    pub fn new(name: &'de str, len: usize) -> Self {
        StructVariantSerializer {
            name,
            map_serializer: StructSerializer::new(len),
        }
    }
}

impl<'a> SerializeStructVariant for StructVariantSerializer<'a> {
    type Ok = Value;
    type Error = SerializerError;

    fn serialize_field<T: ?Sized>(
        &mut self,
        key: &'static str,
        value: &T,
    ) -> Result<(), Self::Error>
        where
            T: Serialize,
    {
        self.map_serializer.serialize_field(key, value)
    }

    fn end(self) -> Result<Self::Ok, Self::Error> {
        let map = self.map_serializer.end()?;

        let map = Value::Map(HashMap::from([(self.name.to_string(), map)]));

        Ok(map)
    }
}

pub struct TupleVariantSerializer<'de> {
    name: &'de str,
    seq_serializer: SeqSerializer,
}

impl<'de> TupleVariantSerializer<'de> {
    pub fn new(name: &'de str, len: usize) -> Self {
        TupleVariantSerializer {
            name,
            seq_serializer: SeqSerializer::new(Some(len)),
        }
    }
}

impl<'a> SerializeTupleVariant for TupleVariantSerializer<'a> {
    type Ok = Value;
    type Error = SerializerError;

    fn serialize_field<T: ?Sized>(&mut self, value: &T) -> Result<(), Self::Error>
        where
            T: Serialize,
    {
        self.seq_serializer.serialize_element(value)
    }

    fn end(self) -> Result<Self::Ok, Self::Error> {
        let map = self.seq_serializer.end()?;

        let map = Value::Map(HashMap::from([(self.name.to_string(), map)]));

        Ok(map)
    }
}