nested-text 0.1.0

use crate::dumper::{dumps, DumpOptions};
use crate::error::{Error, ErrorKind};
use crate::value::Value;

use serde::ser::{self, Serialize};

/// Serialize a value to a NestedText string.
pub fn to_string<T: Serialize>(value: &T) -> Result<String, Error> {
    let v = value.serialize(ValueSerializer)?;
    Ok(dumps(&v, &DumpOptions::default()))
}

/// Serialize a value to a NestedText string with custom options.
pub fn to_string_with_options<T: Serialize>(
    value: &T,
    options: &DumpOptions,
) -> Result<String, Error> {
    let v = value.serialize(ValueSerializer)?;
    Ok(dumps(&v, options))
}

struct ValueSerializer;

impl ser::Serializer for ValueSerializer {
    type Ok = Value;
    type Error = Error;
    type SerializeSeq = SeqSerializer;
    type SerializeTuple = SeqSerializer;
    type SerializeTupleStruct = SeqSerializer;
    type SerializeTupleVariant = TupleVariantSerializer;
    type SerializeMap = MapSerializer;
    type SerializeStruct = MapSerializer;
    type SerializeStructVariant = StructVariantSerializer;

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

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

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

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

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

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

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

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

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

    fn serialize_f32(self, v: f32) -> Result<Value, Error> {
        Ok(Value::String(v.to_string()))
    }

    fn serialize_f64(self, v: f64) -> Result<Value, Error> {
        Ok(Value::String(v.to_string()))
    }

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

    fn serialize_str(self, v: &str) -> Result<Value, Error> {
        Ok(Value::String(v.to_string()))
    }

    fn serialize_bytes(self, _v: &[u8]) -> Result<Value, Error> {
        Err(Error::new(
            ErrorKind::UnsupportedType,
            "NestedText does not support byte arrays",
        ))
    }

    fn serialize_none(self) -> Result<Value, Error> {
        Ok(Value::String(String::new()))
    }

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

    fn serialize_unit(self) -> Result<Value, Error> {
        Ok(Value::String(String::new()))
    }

    fn serialize_unit_struct(self, _name: &'static str) -> Result<Value, Error> {
        Ok(Value::String(String::new()))
    }

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

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

    fn serialize_newtype_variant<T: ?Sized + Serialize>(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
        value: &T,
    ) -> Result<Value, Error> {
        let inner = value.serialize(ValueSerializer)?;
        Ok(Value::Dict(vec![(variant.to_string(), inner)]))
    }

    fn serialize_seq(self, len: Option<usize>) -> Result<SeqSerializer, Error> {
        Ok(SeqSerializer {
            items: Vec::with_capacity(len.unwrap_or(0)),
        })
    }

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

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

    fn serialize_tuple_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
        len: usize,
    ) -> Result<TupleVariantSerializer, Error> {
        Ok(TupleVariantSerializer {
            variant: variant.to_string(),
            items: Vec::with_capacity(len),
        })
    }

    fn serialize_map(self, len: Option<usize>) -> Result<MapSerializer, Error> {
        Ok(MapSerializer {
            pairs: Vec::with_capacity(len.unwrap_or(0)),
            next_key: None,
        })
    }

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

    fn serialize_struct_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
        len: usize,
    ) -> Result<StructVariantSerializer, Error> {
        Ok(StructVariantSerializer {
            variant: variant.to_string(),
            pairs: Vec::with_capacity(len),
        })
    }
}

// Sequence serializer
struct SeqSerializer {
    items: Vec<Value>,
}

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

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

    fn end(self) -> Result<Value, Error> {
        Ok(Value::List(self.items))
    }
}

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

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

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

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

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

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

// Tuple variant serializer
struct TupleVariantSerializer {
    variant: String,
    items: Vec<Value>,
}

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

    fn serialize_field<T: ?Sized + Serialize>(&mut self, value: &T) -> Result<(), Error> {
        self.items.push(value.serialize(ValueSerializer)?);
        Ok(())
    }

    fn end(self) -> Result<Value, Error> {
        Ok(Value::Dict(vec![(
            self.variant,
            Value::List(self.items),
        )]))
    }
}

// Map serializer
struct MapSerializer {
    pairs: Vec<(String, Value)>,
    next_key: Option<String>,
}

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

    fn serialize_key<T: ?Sized + Serialize>(&mut self, key: &T) -> Result<(), Error> {
        let key_value = key.serialize(ValueSerializer)?;
        let key_str = match key_value {
            Value::String(s) => s,
            _ => {
                return Err(Error::new(
                    ErrorKind::UnsupportedType,
                    "map keys must be strings",
                ))
            }
        };
        self.next_key = Some(key_str);
        Ok(())
    }

    fn serialize_value<T: ?Sized + Serialize>(&mut self, value: &T) -> Result<(), Error> {
        let key = self.next_key.take().expect("serialize_value called before serialize_key");
        self.pairs.push((key, value.serialize(ValueSerializer)?));
        Ok(())
    }

    fn end(self) -> Result<Value, Error> {
        Ok(Value::Dict(self.pairs))
    }
}

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

    fn serialize_field<T: ?Sized + Serialize>(
        &mut self,
        key: &'static str,
        value: &T,
    ) -> Result<(), Error> {
        self.pairs
            .push((key.to_string(), value.serialize(ValueSerializer)?));
        Ok(())
    }

    fn end(self) -> Result<Value, Error> {
        Ok(Value::Dict(self.pairs))
    }
}

// Struct variant serializer
struct StructVariantSerializer {
    variant: String,
    pairs: Vec<(String, Value)>,
}

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

    fn serialize_field<T: ?Sized + Serialize>(
        &mut self,
        key: &'static str,
        value: &T,
    ) -> Result<(), Error> {
        self.pairs
            .push((key.to_string(), value.serialize(ValueSerializer)?));
        Ok(())
    }

    fn end(self) -> Result<Value, Error> {
        Ok(Value::Dict(vec![(
            self.variant,
            Value::Dict(self.pairs),
        )]))
    }
}

// Make Error work with serde::ser
impl ser::Error for Error {
    fn custom<T: std::fmt::Display>(msg: T) -> Self {
        Error::new(ErrorKind::UnsupportedType, msg.to_string())
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde::Serialize;

    #[test]
    fn test_serialize_struct() {
        #[derive(Serialize)]
        struct Config {
            name: String,
            age: u32,
        }
        let config = Config {
            name: "Alice".to_string(),
            age: 30,
        };
        let s = to_string(&config).unwrap();
        assert_eq!(s, "name: Alice\nage: 30\n");
    }

    #[test]
    fn test_serialize_vec() {
        let v = vec!["hello", "world"];
        let s = to_string(&v).unwrap();
        assert_eq!(s, "- hello\n- world\n");
    }

    #[test]
    fn test_serialize_bool() {
        #[derive(Serialize)]
        struct Flags {
            debug: bool,
        }
        let flags = Flags { debug: true };
        let s = to_string(&flags).unwrap();
        assert_eq!(s, "debug: true\n");
    }

    #[test]
    fn test_serialize_option() {
        #[derive(Serialize)]
        struct MaybeValue {
            present: Option<String>,
            absent: Option<String>,
        }
        let v = MaybeValue {
            present: Some("hello".to_string()),
            absent: None,
        };
        let s = to_string(&v).unwrap();
        assert_eq!(s, "present: hello\nabsent:\n");
    }

    #[test]
    fn test_serialize_enum() {
        #[derive(Serialize)]
        enum Color {
            Red,
        }
        let s = to_string(&Color::Red).unwrap();
        assert_eq!(s, "> Red\n");
    }

    #[test]
    fn test_serialize_nested() {
        #[derive(Serialize)]
        struct Outer {
            items: Vec<String>,
        }
        let v = Outer {
            items: vec!["a".to_string(), "b".to_string()],
        };
        let s = to_string(&v).unwrap();
        assert_eq!(s, "items:\n    - a\n    - b\n");
    }
}