//! Serializing Rust structures into TOML.
//!
//! This module contains all the Serde support for serializing Rust structures into TOML.

mod array;
mod item;
mod key;
mod table;

pub(crate) use array::*;
pub(crate) use item::*;
pub(crate) use key::*;
pub(crate) use table::*;

/// Errors that can occur when deserializing a type.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Error {
    kind: ErrorKind,
}

impl Error {
    pub(crate) fn custom<T>(msg: T) -> Self
    where
        T: std::fmt::Display,
    {
        Error {
            kind: ErrorKind::Custom(msg.to_string()),
        }
    }
}

impl serde::ser::Error for Error {
    fn custom<T>(msg: T) -> Self
    where
        T: std::fmt::Display,
    {
        Self::custom(msg)
    }
}

impl std::fmt::Display for Error {
    fn fmt(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
        self.kind.fmt(formatter)
    }
}

impl From<crate::TomlError> for Error {
    fn from(e: crate::TomlError) -> Error {
        Self::custom(e)
    }
}

impl From<Error> for crate::TomlError {
    fn from(e: Error) -> crate::TomlError {
        Self::custom(e.to_string())
    }
}

impl std::error::Error for Error {}

impl From<ErrorKind> for Error {
    fn from(kind: ErrorKind) -> Self {
        Self { kind }
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
enum ErrorKind {
    UnsupportedType,
    UnsupportedNone,
    KeyNotString,
    Custom(String),
}

impl std::fmt::Display for ErrorKind {
    fn fmt(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
        match self {
            ErrorKind::UnsupportedType => "unsupported Rust type".fmt(formatter),
            ErrorKind::UnsupportedNone => "unsupported None value".fmt(formatter),
            ErrorKind::KeyNotString => "map key was not a string".fmt(formatter),
            ErrorKind::Custom(s) => s.fmt(formatter),
        }
    }
}

/// Serialize the given data structure as a TOML byte vector.
///
/// Serialization can fail if `T`'s implementation of `Serialize` decides to
/// fail, if `T` contains a map with non-string keys, or if `T` attempts to
/// serialize an unsupported datatype such as an enum, tuple, or tuple struct.
pub fn to_vec<T: ?Sized>(value: &T) -> Result<Vec<u8>, Error>
where
    T: serde::ser::Serialize,
{
    to_string(value).map(|e| e.into_bytes())
}

/// Serialize the given data structure as a String of TOML.
///
/// Serialization can fail if `T`'s implementation of `Serialize` decides to
/// fail, if `T` contains a map with non-string keys, or if `T` attempts to
/// serialize an unsupported datatype such as an enum, tuple, or tuple struct.
///
/// # Examples
///
/// ```
/// use serde::Serialize;
///
/// #[derive(Serialize)]
/// struct Config {
///     database: Database,
/// }
///
/// #[derive(Serialize)]
/// struct Database {
///     ip: String,
///     port: Vec<u16>,
///     connection_max: u32,
///     enabled: bool,
/// }
///
/// let config = Config {
///     database: Database {
///         ip: "192.168.1.1".to_string(),
///         port: vec![8001, 8002, 8003],
///         connection_max: 5000,
///         enabled: false,
///     },
/// };
///
/// let toml = toml::to_string(&config).unwrap();
/// println!("{}", toml)
/// ```
pub fn to_string<T: ?Sized>(value: &T) -> Result<String, Error>
where
    T: serde::ser::Serialize,
{
    to_document(value).map(|e| e.to_string())
}

/// Serialize the given data structure as a "pretty" String of TOML.
///
/// This is identical to `to_string` except the output string has a more
/// "pretty" output. See `Serializer::pretty` for more details.
pub fn to_string_pretty<T: ?Sized>(value: &T) -> Result<String, Error>
where
    T: serde::ser::Serialize,
{
    to_document(value).map(|e| e.to_string())
}

/// Serialize the given data structure into a TOML data structure
///
/// This would allow custom formatting to be applied, mixing with format preserving edits, etc.
pub fn to_document<T: ?Sized>(value: &T) -> Result<crate::Document, Error>
where
    T: serde::ser::Serialize,
{
    let document = value.serialize(Serializer::new())?;
    Ok(document)
}

/// Serialization implementation for TOML.
///
/// This structure implements serialization support for TOML to serialize an
/// arbitrary type to TOML. Note that the TOML format does not support all
/// datatypes in Rust, such as enums, tuples, and tuple structs. These types
/// will generate an error when serialized.
///
/// Currently a serializer always writes its output to an in-memory `String`,
/// which is passed in when creating the serializer itself.
#[derive(Default)]
pub struct Serializer {}

impl Serializer {
    /// Creates a new serializer generate a TOML document.
    pub fn new() -> Self {
        Self {}
    }
}

impl serde::ser::Serializer for Serializer {
    type Ok = crate::Document;
    type Error = Error;
    type SerializeSeq = serde::ser::Impossible<Self::Ok, Self::Error>;
    type SerializeTuple = serde::ser::Impossible<Self::Ok, Self::Error>;
    type SerializeTupleStruct = serde::ser::Impossible<Self::Ok, Self::Error>;
    type SerializeTupleVariant = serde::ser::Impossible<Self::Ok, Self::Error>;
    type SerializeMap = SerializeDocument;
    type SerializeStruct = SerializeDocument;
    type SerializeStructVariant = serde::ser::Impossible<Self::Ok, Self::Error>;

    fn serialize_bool(self, _: bool) -> Result<Self::Ok, Self::Error> {
        Err(ErrorKind::UnsupportedType.into())
    }

    fn serialize_i8(self, v: i8) -> Result<Self::Ok, Self::Error> {
        self.serialize_i64(v as i64)
    }

    fn serialize_i16(self, v: i16) -> Result<Self::Ok, Self::Error> {
        self.serialize_i64(v as i64)
    }

    fn serialize_i32(self, v: i32) -> Result<Self::Ok, Self::Error> {
        self.serialize_i64(v as i64)
    }

    fn serialize_i64(self, _: i64) -> Result<Self::Ok, Self::Error> {
        Err(ErrorKind::UnsupportedType.into())
    }

    fn serialize_u8(self, v: u8) -> Result<Self::Ok, Self::Error> {
        self.serialize_i64(v as i64)
    }

    fn serialize_u16(self, v: u16) -> Result<Self::Ok, Self::Error> {
        self.serialize_i64(v as i64)
    }

    fn serialize_u32(self, v: u32) -> Result<Self::Ok, Self::Error> {
        self.serialize_i64(v as i64)
    }

    fn serialize_u64(self, v: u64) -> Result<Self::Ok, Self::Error> {
        self.serialize_i64(v as i64)
    }

    fn serialize_f32(self, v: f32) -> Result<Self::Ok, Self::Error> {
        self.serialize_f64(v as f64)
    }

    fn serialize_f64(self, _: f64) -> Result<Self::Ok, Self::Error> {
        Err(ErrorKind::UnsupportedType.into())
    }

    fn serialize_char(self, _: char) -> Result<Self::Ok, Self::Error> {
        Err(ErrorKind::UnsupportedType.into())
    }

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

    fn serialize_bytes(self, _: &[u8]) -> Result<Self::Ok, Self::Error> {
        Err(ErrorKind::UnsupportedType.into())
    }

    fn serialize_none(self) -> Result<Self::Ok, Self::Error> {
        Err(ErrorKind::UnsupportedNone.into())
    }

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

    fn serialize_unit(self) -> Result<Self::Ok, Self::Error> {
        Err(ErrorKind::UnsupportedType.into())
    }

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

    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: serde::ser::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: serde::ser::Serialize,
    {
        Err(ErrorKind::UnsupportedType.into())
    }

    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq, Self::Error> {
        Err(ErrorKind::UnsupportedType.into())
    }

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

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

    fn serialize_tuple_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        len: usize,
    ) -> Result<Self::SerializeTupleVariant, Self::Error> {
        self.serialize_seq(Some(len))
    }

    fn serialize_map(self, len: Option<usize>) -> Result<Self::SerializeMap, Self::Error> {
        let serializer = match len {
            Some(len) => SerializeDocument::with_capacity(len),
            None => SerializeDocument::new(),
        };
        Ok(serializer)
    }

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

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