use serde::ser;
use serde::Serialize;

use super::SerializerError;

pub struct ConvertToString;

impl ser::Serializer for ConvertToString {
    type Ok = String;
    type Error = SerializerError;
    type SerializeSeq = ser::Impossible<Self::Ok, Self::Error>;
    type SerializeTuple = ser::Impossible<Self::Ok, Self::Error>;
    type SerializeTupleStruct = ser::Impossible<Self::Ok, Self::Error>;
    type SerializeTupleVariant = ser::Impossible<Self::Ok, Self::Error>;
    type SerializeMap = MapConvertToString;
    type SerializeStruct = StructConvertToString;
    type SerializeStructVariant = ser::Impossible<Self::Ok, Self::Error>;

    fn serialize_bool(self, _value: bool) -> Result<Self::Ok, Self::Error> {
        Err(SerializerError::UnserializableType {
            type_name: "boolean",
        })
    }

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

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

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

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

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

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

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

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

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

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

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

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

    fn serialize_bytes(self, _v: &[u8]) -> Result<Self::Ok, Self::Error> {
        Err(SerializerError::UnserializableType { type_name: "&[u8]" })
    }

    fn serialize_none(self) -> Result<Self::Ok, Self::Error> {
        Err(SerializerError::UnserializableType {
            type_name: "Option",
        })
    }

    fn serialize_some<T: ?Sized>(self, _value: &T) -> Result<Self::Ok, Self::Error>
    where
        T: Serialize,
    {
        Err(SerializerError::UnserializableType {
            type_name: "Option",
        })
    }

    fn serialize_unit(self) -> Result<Self::Ok, Self::Error> {
        Err(SerializerError::UnserializableType { type_name: "()" })
    }

    fn serialize_unit_struct(self, _name: &'static str) -> Result<Self::Ok, Self::Error> {
        Err(SerializerError::UnserializableType {
            type_name: "unit struct",
        })
    }

    fn serialize_unit_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
    ) -> Result<Self::Ok, Self::Error> {
        Err(SerializerError::UnserializableType {
            type_name: "unit 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,
    {
        Err(SerializerError::UnserializableType {
            type_name: "newtype variant",
        })
    }

    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq, Self::Error> {
        Err(SerializerError::UnserializableType {
            type_name: "sequence",
        })
    }

    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple, Self::Error> {
        Err(SerializerError::UnserializableType { type_name: "tuple" })
    }

    fn serialize_tuple_struct(
        self,
        _name: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleStruct, Self::Error> {
        Err(SerializerError::UnserializableType {
            type_name: "tuple struct",
        })
    }

    fn serialize_tuple_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleVariant, Self::Error> {
        Err(SerializerError::UnserializableType {
            type_name: "tuple variant",
        })
    }

    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap, Self::Error> {
        Ok(MapConvertToString {
            text: String::new(),
        })
    }

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

    fn serialize_struct_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeStructVariant, Self::Error> {
        Err(SerializerError::UnserializableType {
            type_name: "struct variant",
        })
    }
}

pub struct MapConvertToString {
    text: String,
}

impl ser::SerializeMap for MapConvertToString {
    type Ok = String;
    type Error = SerializerError;

    fn serialize_key<T: ?Sized>(&mut self, key: &T) -> Result<(), Self::Error>
    where
        T: ser::Serialize,
    {
        let text = key.serialize(ConvertToString)?;
        self.text.push_str(&text);
        self.text.push_str(" ");
        Ok(())
    }

    fn serialize_value<T: ?Sized>(&mut self, value: &T) -> Result<(), Self::Error>
    where
        T: ser::Serialize,
    {
        let text = value.serialize(ConvertToString)?;
        self.text.push_str(&text);
        Ok(())
    }

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

pub struct StructConvertToString {
    text: String,
}

impl ser::SerializeStruct for StructConvertToString {
    type Ok = String;
    type Error = SerializerError;

    fn serialize_field<T: ?Sized>(
        &mut self,
        key: &'static str,
        value: &T,
    ) -> Result<(), Self::Error>
    where
        T: ser::Serialize,
    {
        let value = value.serialize(ConvertToString)?;
        self.text.push_str(key);
        self.text.push_str(" ");
        self.text.push_str(&value);
        Ok(())
    }

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