use super::{Map, Value};
use crate::{Error, Number, Result};
use indexmap::map;
use serde::de::{self, value::StringDeserializer, IntoDeserializer, Visitor};
use serde::{forward_to_deserialize_any, Deserialize, Deserializer};
use std::fmt;

impl<'de> Deserialize<'de> for Value {
    fn deserialize<D>(deserializer: D) -> Result<Value, D::Error>
    where
        D: Deserializer<'de>,
    {
        struct ValueVisitor;

        impl<'de> Visitor<'de> for ValueVisitor {
            type Value = Value;

            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
                formatter.write_str("any valid HCL value")
            }

            fn visit_bool<E>(self, value: bool) -> Result<Value, E> {
                Ok(Value::Bool(value))
            }

            fn visit_i64<E>(self, value: i64) -> Result<Value, E> {
                Ok(Value::Number(value.into()))
            }

            fn visit_u64<E>(self, value: u64) -> Result<Value, E> {
                Ok(Value::Number(value.into()))
            }

            fn visit_f64<E>(self, value: f64) -> Result<Value, E> {
                Ok(Number::from_f64(value).map_or(Value::Null, Value::Number))
            }

            fn visit_str<E>(self, value: &str) -> Result<Value, E>
            where
                E: serde::de::Error,
            {
                self.visit_string(value.to_owned())
            }

            fn visit_string<E>(self, value: String) -> Result<Value, E> {
                Ok(Value::String(value))
            }

            fn visit_none<E>(self) -> Result<Value, E> {
                Ok(Value::Null)
            }

            fn visit_some<D>(self, deserializer: D) -> Result<Value, D::Error>
            where
                D: serde::Deserializer<'de>,
            {
                Deserialize::deserialize(deserializer)
            }

            fn visit_unit<E>(self) -> Result<Value, E> {
                Ok(Value::Null)
            }

            fn visit_seq<V>(self, mut visitor: V) -> Result<Value, V::Error>
            where
                V: de::SeqAccess<'de>,
            {
                let mut vec = Vec::with_capacity(visitor.size_hint().unwrap_or(0));

                while let Some(elem) = visitor.next_element()? {
                    vec.push(elem);
                }

                Ok(Value::Array(vec))
            }

            fn visit_map<V>(self, mut visitor: V) -> Result<Value, V::Error>
            where
                V: de::MapAccess<'de>,
            {
                let mut map = Map::with_capacity(visitor.size_hint().unwrap_or(0));

                while let Some((key, value)) = visitor.next_entry()? {
                    map.insert(key, value);
                }

                Ok(Value::Object(map))
            }
        }

        deserializer.deserialize_any(ValueVisitor)
    }
}

pub struct ValueDeserializer {
    value: Value,
}

impl ValueDeserializer {
    pub fn new(value: Value) -> ValueDeserializer {
        ValueDeserializer { value }
    }
}

impl<'de> IntoDeserializer<'de, Error> for Value {
    type Deserializer = ValueDeserializer;

    fn into_deserializer(self) -> Self::Deserializer {
        ValueDeserializer { value: self }
    }
}

impl<'de> de::Deserializer<'de> for ValueDeserializer {
    type Error = Error;

    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value>
    where
        V: de::Visitor<'de>,
    {
        match self.value {
            Value::Null => visitor.visit_unit(),
            Value::Bool(b) => visitor.visit_bool(b),
            Value::Number(n) => n.deserialize_any(visitor).map_err(de::Error::custom),
            Value::String(s) => visitor.visit_string(s),
            Value::Array(array) => visitor.visit_seq(array.into_deserializer()),
            Value::Object(object) => visitor.visit_map(object.into_deserializer()),
        }
    }

    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Error>
    where
        V: Visitor<'de>,
    {
        match self.value {
            Value::Null => visitor.visit_none(),
            _ => visitor.visit_some(self),
        }
    }

    fn deserialize_enum<V>(
        self,
        _name: &'static str,
        _variants: &'static [&'static str],
        visitor: V,
    ) -> Result<V::Value>
    where
        V: de::Visitor<'de>,
    {
        match self.value {
            Value::String(s) => visitor.visit_enum(s.into_deserializer()),
            Value::Object(object) => visitor.visit_enum(EnumAccess::new(object)),
            _ => Err(de::Error::custom("expected an enum")),
        }
    }

    forward_to_deserialize_any! {
        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
        bytes byte_buf unit unit_struct newtype_struct seq tuple
        tuple_struct map struct identifier ignored_any
    }
}

struct EnumAccess {
    iter: map::IntoIter<String, Value>,
}

impl EnumAccess {
    fn new(map: Map<String, Value>) -> Self {
        EnumAccess {
            iter: map.into_iter(),
        }
    }
}

impl<'de> de::EnumAccess<'de> for EnumAccess {
    type Error = Error;
    type Variant = VariantAccess;

    fn variant_seed<V>(mut self, seed: V) -> Result<(V::Value, Self::Variant)>
    where
        V: de::DeserializeSeed<'de>,
    {
        match self.iter.next() {
            Some((value, variant)) => Ok((
                seed.deserialize::<StringDeserializer<Error>>(value.into_deserializer())?,
                VariantAccess::new(variant),
            )),
            None => Err(de::Error::custom("expected an enum variant")),
        }
    }
}

struct VariantAccess {
    value: Value,
}

impl VariantAccess {
    fn new(value: Value) -> Self {
        VariantAccess { value }
    }
}

impl<'de> de::VariantAccess<'de> for VariantAccess {
    type Error = Error;

    fn unit_variant(self) -> Result<()> {
        Err(de::Error::custom("expected a string"))
    }

    fn newtype_variant_seed<T>(self, seed: T) -> Result<T::Value>
    where
        T: de::DeserializeSeed<'de>,
    {
        seed.deserialize(ValueDeserializer::new(self.value))
    }

    fn tuple_variant<V>(self, _len: usize, visitor: V) -> Result<V::Value>
    where
        V: de::Visitor<'de>,
    {
        de::Deserializer::deserialize_seq(ValueDeserializer::new(self.value), visitor)
    }

    fn struct_variant<V>(self, _fields: &'static [&'static str], visitor: V) -> Result<V::Value>
    where
        V: de::Visitor<'de>,
    {
        de::Deserializer::deserialize_map(ValueDeserializer::new(self.value), visitor)
    }
}