//! Definition of a TOML value

use std::collections::{BTreeMap, HashMap};
use std::hash::Hash;
use std::mem::discriminant;
use std::ops;
use std::str::FromStr;

pub use crate::easy::datetime::*;
pub use crate::easy::map::Map;

/// Representation of a TOML value.
#[derive(PartialEq, Clone, Debug, serde::Serialize, serde::Deserialize)]
#[serde(untagged)]
pub enum Value {
    /// Represents a TOML integer
    Integer(i64),
    /// Represents a TOML float
    Float(f64),
    /// Represents a TOML boolean
    Boolean(bool),
    /// Represents a TOML datetime
    Datetime(Datetime),
    /// Represents a TOML string
    String(String),
    /// Represents a TOML array
    Array(Array),
    /// Represents a TOML table
    Table(Table),
}

/// Type representing a TOML array, payload of the `Value::Array` variant
pub type Array = Vec<Value>;

/// Type representing a TOML table, payload of the `Value::Table` variant.
/// By default it is backed by a BTreeMap, enable the `preserve_order` feature
/// to use a LinkedHashMap instead.
pub type Table = Map<String, Value>;

impl Value {
    /// Convert a `T` into `toml::Value` which is an enum that can represent
    /// any valid TOML data.
    ///
    /// This conversion can fail if `T`'s implementation of `Serialize` decides to
    /// fail, or if `T` contains a map with non-string keys.
    pub fn try_from<T>(value: T) -> Result<Value, crate::TomlError>
    where
        T: serde::ser::Serialize,
    {
        let doc = super::to_document(&value)?;
        let value = super::from_document(doc)?;
        Ok(value)
    }

    /// Interpret a `toml::Value` as an instance of type `T`.
    ///
    /// This conversion can fail if the structure of the `Value` does not match the
    /// structure expected by `T`, for example if `T` is a struct type but the
    /// `Value` contains something other than a TOML table. It can also fail if the
    /// structure is correct but `T`'s implementation of `Deserialize` decides that
    /// something is wrong with the data, for example required struct fields are
    /// missing from the TOML map or some number is too big to fit in the expected
    /// primitive type.
    pub fn try_into<T>(self) -> Result<T, crate::TomlError>
    where
        T: serde::de::Deserialize<'static>,
    {
        let doc = super::to_document(&self)?;
        let value = super::from_document(doc)?;
        Ok(value)
    }

    /// Index into a TOML array or map. A string index can be used to access a
    /// value in a map, and a usize index can be used to access an element of an
    /// array.
    ///
    /// Returns `None` if the type of `self` does not match the type of the
    /// index, for example if the index is a string and `self` is an array or a
    /// number. Also returns `None` if the given key does not exist in the map
    /// or the given index is not within the bounds of the array.
    pub fn get<I: Index>(&self, index: I) -> Option<&Value> {
        index.index(self)
    }

    /// Mutably index into a TOML array or map. A string index can be used to
    /// access a value in a map, and a usize index can be used to access an
    /// element of an array.
    ///
    /// Returns `None` if the type of `self` does not match the type of the
    /// index, for example if the index is a string and `self` is an array or a
    /// number. Also returns `None` if the given key does not exist in the map
    /// or the given index is not within the bounds of the array.
    pub fn get_mut<I: Index>(&mut self, index: I) -> Option<&mut Value> {
        index.index_mut(self)
    }

    /// Extracts the integer value if it is an integer.
    pub fn as_integer(&self) -> Option<i64> {
        match *self {
            Value::Integer(i) => Some(i),
            _ => None,
        }
    }

    /// Tests whether this value is an integer.
    pub fn is_integer(&self) -> bool {
        self.as_integer().is_some()
    }

    /// Extracts the float value if it is a float.
    pub fn as_float(&self) -> Option<f64> {
        match *self {
            Value::Float(f) => Some(f),
            _ => None,
        }
    }

    /// Tests whether this value is a float.
    pub fn is_float(&self) -> bool {
        self.as_float().is_some()
    }

    /// Extracts the boolean value if it is a boolean.
    pub fn as_bool(&self) -> Option<bool> {
        match *self {
            Value::Boolean(b) => Some(b),
            _ => None,
        }
    }

    /// Tests whether this value is a boolean.
    pub fn is_bool(&self) -> bool {
        self.as_bool().is_some()
    }

    /// Extracts the string of this value if it is a string.
    pub fn as_str(&self) -> Option<&str> {
        match *self {
            Value::String(ref s) => Some(&**s),
            _ => None,
        }
    }

    /// Tests if this value is a string.
    pub fn is_str(&self) -> bool {
        self.as_str().is_some()
    }

    /// Extracts the datetime value if it is a datetime.
    ///
    /// Note that a parsed TOML value will only contain ISO 8601 dates. An
    /// example date is:
    ///
    /// ```notrust
    /// 1979-05-27T07:32:00Z
    /// ```
    pub fn as_datetime(&self) -> Option<&Datetime> {
        match *self {
            Value::Datetime(ref s) => Some(s),
            _ => None,
        }
    }

    /// Tests whether this value is a datetime.
    pub fn is_datetime(&self) -> bool {
        self.as_datetime().is_some()
    }

    /// Extracts the array value if it is an array.
    pub fn as_array(&self) -> Option<&Vec<Value>> {
        match *self {
            Value::Array(ref s) => Some(s),
            _ => None,
        }
    }

    /// Extracts the array value if it is an array.
    pub fn as_array_mut(&mut self) -> Option<&mut Vec<Value>> {
        match *self {
            Value::Array(ref mut s) => Some(s),
            _ => None,
        }
    }

    /// Tests whether this value is an array.
    pub fn is_array(&self) -> bool {
        self.as_array().is_some()
    }

    /// Extracts the table value if it is a table.
    pub fn as_table(&self) -> Option<&Table> {
        match *self {
            Value::Table(ref s) => Some(s),
            _ => None,
        }
    }

    /// Extracts the table value if it is a table.
    pub fn as_table_mut(&mut self) -> Option<&mut Table> {
        match *self {
            Value::Table(ref mut s) => Some(s),
            _ => None,
        }
    }

    /// Tests whether this value is a table.
    pub fn is_table(&self) -> bool {
        self.as_table().is_some()
    }

    /// Tests whether this and another value have the same type.
    pub fn same_type(&self, other: &Value) -> bool {
        discriminant(self) == discriminant(other)
    }

    /// Returns a human-readable representation of the type of this value.
    pub fn type_str(&self) -> &'static str {
        match *self {
            Value::String(..) => "string",
            Value::Integer(..) => "integer",
            Value::Float(..) => "float",
            Value::Boolean(..) => "boolean",
            Value::Datetime(..) => "datetime",
            Value::Array(..) => "array",
            Value::Table(..) => "table",
        }
    }
}

impl std::fmt::Display for Value {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        super::to_string_pretty(self)
            .map_err(|_| std::fmt::Error)?
            .fmt(f)
    }
}

impl<I> ops::Index<I> for Value
where
    I: Index,
{
    type Output = Value;

    fn index(&self, index: I) -> &Value {
        self.get(index).expect("index not found")
    }
}

impl<I> ops::IndexMut<I> for Value
where
    I: Index,
{
    fn index_mut(&mut self, index: I) -> &mut Value {
        self.get_mut(index).expect("index not found")
    }
}

impl<'a> From<&'a str> for Value {
    #[inline]
    fn from(val: &'a str) -> Value {
        Value::String(val.to_string())
    }
}

impl<V: Into<Value>> From<Vec<V>> for Value {
    fn from(val: Vec<V>) -> Value {
        Value::Array(val.into_iter().map(|v| v.into()).collect())
    }
}

impl<S: Into<String>, V: Into<Value>> From<BTreeMap<S, V>> for Value {
    fn from(val: BTreeMap<S, V>) -> Value {
        let table = val.into_iter().map(|(s, v)| (s.into(), v.into())).collect();

        Value::Table(table)
    }
}

impl<S: Into<String> + Hash + Eq, V: Into<Value>> From<HashMap<S, V>> for Value {
    fn from(val: HashMap<S, V>) -> Value {
        let table = val.into_iter().map(|(s, v)| (s.into(), v.into())).collect();

        Value::Table(table)
    }
}

macro_rules! impl_into_value {
    ($variant:ident : $T:ty) => {
        impl From<$T> for Value {
            #[inline]
            fn from(val: $T) -> Value {
                Value::$variant(val.into())
            }
        }
    };
}

impl_into_value!(String: String);
impl_into_value!(Integer: i64);
impl_into_value!(Integer: i32);
impl_into_value!(Integer: i8);
impl_into_value!(Integer: u8);
impl_into_value!(Integer: u32);
impl_into_value!(Float: f64);
impl_into_value!(Float: f32);
impl_into_value!(Boolean: bool);
impl_into_value!(Datetime: Datetime);
impl_into_value!(Table: Table);

/// Types that can be used to index a `toml_edit::easy::Value`
///
/// Currently this is implemented for `usize` to index arrays and `str` to index
/// tables.
///
/// This trait is sealed and not intended for implementation outside of the
/// `toml` crate.
pub trait Index: crate::private::Sealed {
    #[doc(hidden)]
    fn index<'a>(&self, val: &'a Value) -> Option<&'a Value>;
    #[doc(hidden)]
    fn index_mut<'a>(&self, val: &'a mut Value) -> Option<&'a mut Value>;
}

impl Index for usize {
    fn index<'a>(&self, val: &'a Value) -> Option<&'a Value> {
        match *val {
            Value::Array(ref a) => a.get(*self),
            _ => None,
        }
    }

    fn index_mut<'a>(&self, val: &'a mut Value) -> Option<&'a mut Value> {
        match *val {
            Value::Array(ref mut a) => a.get_mut(*self),
            _ => None,
        }
    }
}

impl Index for str {
    fn index<'a>(&self, val: &'a Value) -> Option<&'a Value> {
        match *val {
            Value::Table(ref a) => a.get(self),
            _ => None,
        }
    }

    fn index_mut<'a>(&self, val: &'a mut Value) -> Option<&'a mut Value> {
        match *val {
            Value::Table(ref mut a) => a.get_mut(self),
            _ => None,
        }
    }
}

impl Index for String {
    fn index<'a>(&self, val: &'a Value) -> Option<&'a Value> {
        self[..].index(val)
    }

    fn index_mut<'a>(&self, val: &'a mut Value) -> Option<&'a mut Value> {
        self[..].index_mut(val)
    }
}

impl<'s, T: ?Sized> Index for &'s T
where
    T: Index,
{
    fn index<'a>(&self, val: &'a Value) -> Option<&'a Value> {
        (**self).index(val)
    }

    fn index_mut<'a>(&self, val: &'a mut Value) -> Option<&'a mut Value> {
        (**self).index_mut(val)
    }
}

impl FromStr for Value {
    type Err = crate::easy::de::Error;
    fn from_str(s: &str) -> Result<Value, Self::Err> {
        crate::easy::from_str(s)
    }
}