libconfig/

value.rs

//! A dynamically-typed representation of libconfig data
//!
//! This module provides the `Value` enum which represents any valid libconfig value.
//! It can be used when you don't know the structure of the data at compile time.

use crate::de::is_list_context;
use crate::error::{Error, Result};
use indexmap::IndexMap;
use serde::de::{self, Deserialize, Deserializer, MapAccess, SeqAccess, Visitor};
use serde::ser::{Serialize, SerializeMap, SerializeSeq, Serializer};
use std::fmt;
use std::ops::Index;

/// A dynamically-typed value that can represent any libconfig data
///
/// # Examples
///
/// ```
/// use libconfig::Value;
///
/// let config = r#"
///     {
///         name = "My App";
///         version = 1;
///         enabled = true;
///         ports = [8080, 8081, 8082];
///     }
/// "#;
///
/// let v = Value::from_str(config).unwrap();
///
/// assert_eq!(v["name"], "My App");
/// assert_eq!(v["version"], 1);
/// assert_eq!(v["enabled"], true);
/// assert_eq!(v["ports"][0], 8080);
/// ```
#[derive(Debug, Clone, PartialEq)]
pub enum Value {
    /// Represents a boolean value
    Bool(bool),

    /// Represents a 32-bit integer
    Integer(i32),

    /// Represents a 64-bit integer
    Integer64(i64),

    /// Represents a floating point number
    Float(f64),

    /// Represents a string
    String(String),

    /// Represents an array (homogeneous sequence)
    Array(Vec<Value>),

    /// Represents a list (heterogeneous sequence)
    List(Vec<Value>),

    /// Represents a group (object/map)
    Group(Map),
}

/// A map of string keys to `Value`s, representing a libconfig group
/// Uses IndexMap to preserve insertion order
pub type Map = IndexMap<String, Value>;

/// A single segment of a libconfig path.
#[derive(Debug, Clone, PartialEq)]
enum PathSegment<'a> {
    /// A named key for indexing into a Group
    Key(&'a str),
    /// A numeric index for indexing into an Array or List
    Index(usize),
}

/// Parses a libconfig path string into a sequence of segments.
///
/// Supports:
///   - Dot-separated keys: `"application.window.title"`
///   - Bracket indices: `"items.[0].title"` (libconfig spec)
///   - Bare numeric indices: `"items.0"` (backward compat)
///
/// Returns `None` if the path is empty or contains malformed segments.
fn parse_path(path: &str) -> Option<Vec<PathSegment<'_>>> {
    if path.is_empty() {
        return None;
    }

    let mut segments = Vec::new();
    for part in path.split('.') {
        if part.is_empty() {
            return None;
        }

        if part.starts_with('[') && part.ends_with(']') {
            let inner = &part[1..part.len() - 1];
            let index: usize = inner.parse().ok()?;
            segments.push(PathSegment::Index(index));
        } else if let Ok(index) = part.parse::<usize>() {
            segments.push(PathSegment::Index(index));
        } else {
            segments.push(PathSegment::Key(part));
        }
    }

    if segments.is_empty() {
        None
    } else {
        Some(segments)
    }
}

impl Value {
    /// Returns true if the value is a boolean
    pub fn is_bool(&self) -> bool {
        matches!(self, Value::Bool(_))
    }

    /// Returns true if the value is an integer (32-bit or 64-bit)
    pub fn is_integer(&self) -> bool {
        matches!(self, Value::Integer(_) | Value::Integer64(_))
    }

    /// Returns true if the value is a 32-bit integer
    pub fn is_i32(&self) -> bool {
        matches!(self, Value::Integer(_))
    }

    /// Returns true if the value is a 64-bit integer
    pub fn is_i64(&self) -> bool {
        matches!(self, Value::Integer64(_))
    }

    /// Returns true if the value is a float
    pub fn is_float(&self) -> bool {
        matches!(self, Value::Float(_))
    }

    /// Returns true if the value is a number (integer or float)
    pub fn is_number(&self) -> bool {
        matches!(
            self,
            Value::Integer(_) | Value::Integer64(_) | Value::Float(_)
        )
    }

    /// Returns true if the value is a string
    pub fn is_string(&self) -> bool {
        matches!(self, Value::String(_))
    }

    /// Returns true if the value is an array
    pub fn is_array(&self) -> bool {
        matches!(self, Value::Array(_))
    }

    /// Returns true if the value is a list
    pub fn is_list(&self) -> bool {
        matches!(self, Value::List(_))
    }

    /// Returns true if the value is a group (object)
    pub fn is_group(&self) -> bool {
        matches!(self, Value::Group(_))
    }

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

    /// If the value is an integer, returns it as i32. Returns None otherwise.
    pub fn as_i32(&self) -> Option<i32> {
        match self {
            Value::Integer(i) => Some(*i),
            Value::Integer64(i) if *i >= i32::MIN as i64 && *i <= i32::MAX as i64 => {
                Some(*i as i32)
            }
            _ => None,
        }
    }

    /// If the value is an integer, returns it as i64. Returns None otherwise.
    pub fn as_i64(&self) -> Option<i64> {
        match self {
            Value::Integer(i) => Some(*i as i64),
            Value::Integer64(i) => Some(*i),
            _ => None,
        }
    }

    /// If the value is a float, returns it. Returns None otherwise.
    pub fn as_f64(&self) -> Option<f64> {
        match self {
            Value::Float(f) => Some(*f),
            Value::Integer(i) => Some(*i as f64),
            Value::Integer64(i) => Some(*i as f64),
            _ => None,
        }
    }

    /// If the value is a string, returns a reference to it. Returns None otherwise.
    pub fn as_str(&self) -> Option<&str> {
        match self {
            Value::String(s) => Some(s),
            _ => None,
        }
    }

    /// If the value is an array or list, returns a reference to it. Returns None otherwise.
    pub fn as_array(&self) -> Option<&Vec<Value>> {
        match self {
            Value::Array(arr) | Value::List(arr) => Some(arr),
            _ => None,
        }
    }

    /// If the value is a group, returns a reference to the map. Returns None otherwise.
    pub fn as_group(&self) -> Option<&Map> {
        match self {
            Value::Group(map) => Some(map),
            _ => None,
        }
    }

    /// Gets a reference to a value in a group by key
    ///
    /// Returns None if the value is not a group or the key doesn't exist.
    pub fn get<S: AsRef<str>>(&self, key: S) -> Option<&Value> {
        match self {
            Value::Group(map) => map.get(key.as_ref()),
            _ => None,
        }
    }

    /// Gets a mutable reference to a value in a group by key
    ///
    /// Returns None if the value is not a group or the key doesn't exist.
    pub fn get_mut<S: AsRef<str>>(&mut self, key: S) -> Option<&mut Value> {
        match self {
            Value::Group(map) => map.get_mut(key.as_ref()),
            _ => None,
        }
    }

    /// Gets a reference to a value in an array/list by index
    ///
    /// Returns None if the value is not an array/list or the index is out of bounds.
    pub fn get_index(&self, index: usize) -> Option<&Value> {
        match self {
            Value::Array(arr) | Value::List(arr) => arr.get(index),
            _ => None,
        }
    }

    /// Looks up a value by a dotted path like "application.window.title"
    ///
    /// Returns None if any part of the path doesn't exist.
    ///
    /// # Examples
    ///
    /// ```
    /// use libconfig::Value;
    ///
    /// let config = r#"
    ///     {
    ///         application = {
    ///             window = {
    ///                 title = "My App";
    ///             };
    ///         };
    ///     }
    /// "#;
    ///
    /// let v = Value::from_str(config).unwrap();
    /// assert_eq!(v.lookup("application.window.title").and_then(|v| v.as_str()), Some("My App"));
    /// ```
    pub fn lookup(&self, path: &str) -> Option<&Value> {
        let segments = parse_path(path)?;
        let mut current = self;
        for segment in &segments {
            match segment {
                PathSegment::Key(key) => current = current.get(*key)?,
                PathSegment::Index(index) => current = current.get_index(*index)?,
            }
        }
        Some(current)
    }

    /// Looks up a mutable reference to a value by a dotted path like "application.window.title"
    ///
    /// Returns None if any part of the path doesn't exist.
    /// Supports both bracket notation (`items.[0]`) and bare numeric (`items.0`).
    ///
    /// # Examples
    ///
    /// ```
    /// use libconfig::Value;
    ///
    /// let config = r#"
    ///     {
    ///         ports = [80, 443];
    ///     }
    /// "#;
    ///
    /// let mut v = Value::from_str(config).unwrap();
    /// *v.lookup_mut("ports.[0]").unwrap() = Value::Integer(8080);
    /// assert_eq!(v["ports.0"], 8080);
    /// ```
    pub fn lookup_mut(&mut self, path: &str) -> Option<&mut Value> {
        let segments = parse_path(path)?;
        let mut current = self;
        for segment in &segments {
            match segment {
                PathSegment::Key(key) => match current {
                    Value::Group(map) => current = map.get_mut(*key)?,
                    _ => return None,
                },
                PathSegment::Index(index) => match current {
                    Value::Array(arr) | Value::List(arr) => current = arr.get_mut(*index)?,
                    _ => return None,
                },
            }
        }
        Some(current)
    }

    /// Sets a value at the given path, creating intermediate `Group` nodes as needed.
    ///
    /// Returns `Some(())` on success, or `None` if the path is invalid or an
    /// intermediate value is not a Group/Array/List.
    ///
    /// Array/list indices must refer to existing elements (no auto-extension).
    ///
    /// # Examples
    ///
    /// ```
    /// use libconfig::Value;
    /// use indexmap::IndexMap;
    ///
    /// let mut v = Value::Group(IndexMap::new());
    /// v.set("a.b.c", Value::Integer(42));
    /// assert_eq!(v.lookup("a.b.c").unwrap().as_i32(), Some(42));
    /// ```
    pub fn set(&mut self, path: &str, value: Value) -> Option<()> {
        let segments = parse_path(path)?;
        if segments.is_empty() {
            return None;
        }

        let mut current = self;

        // Navigate to the parent, creating intermediate Groups as needed
        for segment in &segments[..segments.len() - 1] {
            match segment {
                PathSegment::Key(key) => match current {
                    Value::Group(map) => {
                        current = map
                            .entry(key.to_string())
                            .or_insert_with(|| Value::Group(IndexMap::new()));
                    }
                    _ => return None,
                },
                PathSegment::Index(index) => match current {
                    Value::Array(arr) | Value::List(arr) => {
                        current = arr.get_mut(*index)?;
                    }
                    _ => return None,
                },
            }
        }

        // Apply the final segment
        match segments.last().unwrap() {
            PathSegment::Key(key) => match current {
                Value::Group(map) => {
                    map.insert(key.to_string(), value);
                    Some(())
                }
                _ => None,
            },
            PathSegment::Index(index) => match current {
                Value::Array(arr) | Value::List(arr) => {
                    if *index < arr.len() {
                        arr[*index] = value;
                        Some(())
                    } else {
                        None
                    }
                }
                _ => None,
            },
        }
    }

    /// Removes a value at the given path and returns it.
    ///
    /// For group members, the key-value pair is removed.
    /// For array/list elements, the element is removed and subsequent elements shift down.
    ///
    /// Returns `None` if the path is invalid or the target doesn't exist.
    ///
    /// # Examples
    ///
    /// ```
    /// use libconfig::Value;
    ///
    /// let mut v = Value::from_str(r#"{ a = 1; b = 2; c = 3; }"#).unwrap();
    /// let removed = v.remove("b");
    /// assert_eq!(removed, Some(Value::Integer(2)));
    /// assert!(v.lookup("b").is_none());
    /// ```
    pub fn remove(&mut self, path: &str) -> Option<Value> {
        let segments = parse_path(path)?;
        if segments.is_empty() {
            return None;
        }

        let mut current = self;

        // Navigate to the parent
        for segment in &segments[..segments.len() - 1] {
            match segment {
                PathSegment::Key(key) => match current {
                    Value::Group(map) => current = map.get_mut(*key)?,
                    _ => return None,
                },
                PathSegment::Index(index) => match current {
                    Value::Array(arr) | Value::List(arr) => current = arr.get_mut(*index)?,
                    _ => return None,
                },
            }
        }

        // Remove at the final segment
        match segments.last().unwrap() {
            PathSegment::Key(key) => match current {
                Value::Group(map) => map.shift_remove(*key),
                _ => None,
            },
            PathSegment::Index(index) => match current {
                Value::Array(arr) | Value::List(arr) => {
                    if *index < arr.len() {
                        Some(arr.remove(*index))
                    } else {
                        None
                    }
                }
                _ => None,
            },
        }
    }

    /// Parse a libconfig string into a `Value`.
    ///
    /// # Examples
    ///
    /// ```
    /// use libconfig::Value;
    ///
    /// let v = Value::from_str("{ name = \"test\"; version = 1; }").unwrap();
    /// assert_eq!(v["name"], "test");
    /// assert_eq!(v["version"], 1);
    /// ```
    pub fn from_str(s: &str) -> Result<Value> {
        crate::from_str(s)
    }

    /// Serialize this value to a libconfig string.
    ///
    /// The output always wraps top-level groups in braces. For implicit
    /// (no braces) output, use [`Config::from`] or [`Config::from_str`].
    ///
    /// # Examples
    ///
    /// ```
    /// use libconfig::Value;
    ///
    /// let v = Value::Integer(42);
    /// assert_eq!(v.to_string().unwrap(), "42");
    /// ```
    pub fn to_string(&self) -> Result<String> {
        crate::to_string(self)
    }
}

// Implement Index for convenient access with []
// Supports dotted path notation (e.g., value["misc.location"])
impl Index<&str> for Value {
    type Output = Value;

    fn index(&self, key: &str) -> &Self::Output {
        self.lookup(key).expect("key not found in group")
    }
}

impl Index<usize> for Value {
    type Output = Value;

    fn index(&self, index: usize) -> &Self::Output {
        self.get_index(index).expect("index out of bounds")
    }
}

// Implement PartialEq for comparing with native types
impl PartialEq<bool> for Value {
    fn eq(&self, other: &bool) -> bool {
        self.as_bool() == Some(*other)
    }
}

impl PartialEq<i32> for Value {
    fn eq(&self, other: &i32) -> bool {
        self.as_i32() == Some(*other)
    }
}

impl PartialEq<i64> for Value {
    fn eq(&self, other: &i64) -> bool {
        self.as_i64() == Some(*other)
    }
}

impl PartialEq<f64> for Value {
    fn eq(&self, other: &f64) -> bool {
        self.as_f64() == Some(*other)
    }
}

impl PartialEq<str> for Value {
    fn eq(&self, other: &str) -> bool {
        self.as_str() == Some(other)
    }
}

impl PartialEq<&str> for Value {
    fn eq(&self, other: &&str) -> bool {
        self.as_str() == Some(*other)
    }
}

impl PartialEq<String> for Value {
    fn eq(&self, other: &String) -> bool {
        self.as_str() == Some(other.as_str())
    }
}

// Implement Display for pretty printing
impl fmt::Display for Value {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Value::Bool(b) => write!(f, "{}", b),
            Value::Integer(i) => write!(f, "{}", i),
            Value::Integer64(i) => write!(f, "{}L", i),
            Value::Float(fl) => write!(f, "{}", fl),
            Value::String(s) => write!(f, "\"{}\"", s),
            Value::Array(arr) => {
                write!(f, "[")?;
                for (i, v) in arr.iter().enumerate() {
                    if i > 0 {
                        write!(f, ", ")?;
                    }
                    write!(f, "{}", v)?;
                }
                write!(f, "]")
            }
            Value::List(arr) => {
                write!(f, "(")?;
                for (i, v) in arr.iter().enumerate() {
                    if i > 0 {
                        write!(f, ", ")?;
                    }
                    write!(f, "{}", v)?;
                }
                write!(f, ")")
            }
            Value::Group(map) => {
                write!(f, "{{")?;
                for (i, (k, v)) in map.iter().enumerate() {
                    if i > 0 {
                        write!(f, ", ")?;
                    }
                    write!(f, "{}: {}", k, v)?;
                }
                write!(f, "}}")
            }
        }
    }
}

// Implement Serialize for Value
impl Serialize for Value {
    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        match self {
            Value::Bool(b) => serializer.serialize_bool(*b),
            Value::Integer(i) => serializer.serialize_i32(*i),
            Value::Integer64(i) => serializer.serialize_i64(*i),
            Value::Float(f) => serializer.serialize_f64(*f),
            Value::String(s) => serializer.serialize_str(s),
            Value::Array(arr) => {
                let mut seq = serializer.serialize_seq(Some(arr.len()))?;
                for element in arr {
                    seq.serialize_element(element)?;
                }
                seq.end()
            }
            Value::List(arr) => {
                use serde::ser::SerializeTuple;
                let mut tup = serializer.serialize_tuple(arr.len())?;
                for element in arr {
                    tup.serialize_element(element)?;
                }
                tup.end()
            }
            Value::Group(map) => {
                let mut map_ser = serializer.serialize_map(Some(map.len()))?;
                for (k, v) in map {
                    map_ser.serialize_entry(k, v)?;
                }
                map_ser.end()
            }
        }
    }
}

// Implement Deserialize for Value
impl<'de> Deserialize<'de> for Value {
    fn deserialize<D>(deserializer: D) -> std::result::Result<Value, D::Error>
    where
        D: Deserializer<'de>,
    {
        deserializer.deserialize_any(ValueVisitor)
    }
}

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 libconfig value")
    }

    fn visit_bool<E>(self, value: bool) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        Ok(Value::Bool(value))
    }

    fn visit_i8<E>(self, value: i8) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        Ok(Value::Integer(value as i32))
    }

    fn visit_i16<E>(self, value: i16) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        Ok(Value::Integer(value as i32))
    }

    fn visit_i32<E>(self, value: i32) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        Ok(Value::Integer(value))
    }

    fn visit_i64<E>(self, value: i64) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        Ok(Value::Integer64(value))
    }

    fn visit_u8<E>(self, value: u8) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        Ok(Value::Integer(value as i32))
    }

    fn visit_u16<E>(self, value: u16) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        Ok(Value::Integer(value as i32))
    }

    fn visit_u32<E>(self, value: u32) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        if value <= i32::MAX as u32 {
            Ok(Value::Integer(value as i32))
        } else {
            Ok(Value::Integer64(value as i64))
        }
    }

    fn visit_u64<E>(self, value: u64) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        if value <= i32::MAX as u64 {
            Ok(Value::Integer(value as i32))
        } else {
            Ok(Value::Integer64(value as i64))
        }
    }

    fn visit_f32<E>(self, value: f32) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        Ok(Value::Float(value as f64))
    }

    fn visit_f64<E>(self, value: f64) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        Ok(Value::Float(value))
    }

    fn visit_str<E>(self, value: &str) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        Ok(Value::String(value.to_string()))
    }

    fn visit_borrowed_str<E>(self, value: &'de str) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        Ok(Value::String(value.to_string()))
    }

    fn visit_string<E>(self, value: String) -> std::result::Result<Value, E>
    where
        E: de::Error,
    {
        Ok(Value::String(value))
    }

    fn visit_seq<A>(self, mut seq: A) -> std::result::Result<Value, A::Error>
    where
        A: SeqAccess<'de>,
    {
        let is_list = is_list_context();
        let mut values = Vec::new();
        while let Some(value) = seq.next_element()? {
            values.push(value);
        }
        if is_list {
            Ok(Value::List(values))
        } else {
            Ok(Value::Array(values))
        }
    }

    fn visit_map<A>(self, mut map: A) -> std::result::Result<Value, A::Error>
    where
        A: MapAccess<'de>,
    {
        let mut values = Map::new();
        while let Some((key, value)) = map.next_entry()? {
            values.insert(key, value);
        }
        Ok(Value::Group(values))
    }
}

/// Convert a `Value` to a specific type `T`
///
/// # Examples
///
/// ```
/// use libconfig::Value;
///
/// let v = Value::from_str("42").unwrap();
/// let num: i32 = libconfig::from_value(v).unwrap();
/// assert_eq!(num, 42);
/// ```
pub fn from_value<T>(value: Value) -> Result<T>
where
    T: de::DeserializeOwned,
{
    T::deserialize(value).map_err(|e| Error::Message(format!("failed to deserialize: {}", e)))
}

/// Internal implementation with indentation tracking
fn to_string_format_impl(value: &Value, indent_level: usize, is_nested: bool) -> Result<String> {
    const INDENT_SIZE: usize = 2;

    match value {
        Value::Bool(b) => Ok(if *b {
            "true".to_string()
        } else {
            "false".to_string()
        }),
        Value::Integer(i) => Ok(i.to_string()),
        Value::Integer64(i) => Ok(format!("{}L", i)),
        Value::Float(f) => {
            let s = f.to_string();
            if !s.contains('.') && !s.contains('e') && !s.contains('E') {
                Ok(format!("{}.0", s))
            } else {
                Ok(s)
            }
        }
        Value::String(s) => {
            let mut result = String::from("\"");
            for ch in s.chars() {
                match ch {
                    '"' => result.push_str("\\\""),
                    '\\' => result.push_str("\\\\"),
                    '\n' => result.push_str("\\n"),
                    '\r' => result.push_str("\\r"),
                    '\t' => result.push_str("\\t"),
                    '\x0C' => result.push_str("\\f"),
                    '\x08' => result.push_str("\\b"),
                    '\x0B' => result.push_str("\\v"),
                    '\x07' => result.push_str("\\a"),
                    _ => result.push(ch),
                }
            }
            result.push('"');
            Ok(result)
        }
        Value::Array(arr) => {
            let mut result = String::from("[");
            for (i, elem) in arr.iter().enumerate() {
                if i > 0 {
                    result.push_str(", ");
                }
                result.push_str(&to_string_format_impl(elem, indent_level, true)?);
            }
            result.push(']');
            Ok(result)
        }
        Value::List(arr) => {
            let mut result = String::from("(");
            for (i, elem) in arr.iter().enumerate() {
                if i > 0 {
                    result.push_str(", ");
                }
                result.push_str(&to_string_format_impl(elem, indent_level, true)?);
            }
            result.push(')');
            Ok(result)
        }
        Value::Group(map) => {
            if !is_nested {
                let mut output = String::new();
                let mut first = true;
                for (key, val) in map {
                    if !first {
                        output.push(';');
                        output.push('\n');
                    }
                    first = false;
                    output.push_str(key);
                    output.push_str(" = ");
                    let val_str = to_string_format_impl(val, indent_level, true)?;
                    output.push_str(&val_str);
                }
                if !output.is_empty() {
                    output.push(';');
                }
                Ok(output)
            } else {
                // Explicit groups or nested groups always have braces
                let mut output = String::from("{");
                let next_indent = indent_level + 1;
                let indent_str = " ".repeat(next_indent * INDENT_SIZE);

                let mut first = true;
                for (key, val) in map {
                    if !first {
                        output.push(';');
                    }
                    output.push('\n');
                    output.push_str(&indent_str);
                    first = false;

                    output.push_str(key);
                    output.push_str(" = ");
                    let val_str = to_string_format_impl(val, next_indent, true)?;
                    output.push_str(&val_str);
                }

                if !map.is_empty() {
                    output.push(';');
                }
                output.push('\n');
                output.push_str(&" ".repeat(indent_level * INDENT_SIZE));
                output.push('}');
                Ok(output)
            }
        }
    }
}

/// Deserializer implementation for Value
impl<'de> Deserializer<'de> for Value {
    type Error = Error;

    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value>
    where
        V: Visitor<'de>,
    {
        match self {
            Value::Bool(b) => visitor.visit_bool(b),
            Value::Integer(i) => visitor.visit_i32(i),
            Value::Integer64(i) => visitor.visit_i64(i),
            Value::Float(f) => visitor.visit_f64(f),
            Value::String(s) => visitor.visit_string(s),
            Value::Array(arr) | Value::List(arr) => {
                visitor.visit_seq(SeqDeserializer::new(arr.into_iter()))
            }
            Value::Group(map) => visitor.visit_map(MapDeserializer::new(map.into_iter())),
        }
    }

    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value>
    where
        V: Visitor<'de>,
    {
        visitor.visit_some(self)
    }

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

struct SeqDeserializer {
    iter: std::vec::IntoIter<Value>,
}

impl SeqDeserializer {
    fn new(iter: std::vec::IntoIter<Value>) -> Self {
        SeqDeserializer { iter }
    }
}

impl<'de> SeqAccess<'de> for SeqDeserializer {
    type Error = Error;

    fn next_element_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>>
    where
        T: de::DeserializeSeed<'de>,
    {
        match self.iter.next() {
            Some(value) => seed.deserialize(value).map(Some),
            None => Ok(None),
        }
    }
}

struct MapDeserializer {
    iter: indexmap::map::IntoIter<String, Value>,
    value: Option<Value>,
}

impl MapDeserializer {
    fn new(iter: indexmap::map::IntoIter<String, Value>) -> Self {
        MapDeserializer { iter, value: None }
    }
}

impl<'de> MapAccess<'de> for MapDeserializer {
    type Error = Error;

    fn next_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>>
    where
        K: de::DeserializeSeed<'de>,
    {
        match self.iter.next() {
            Some((key, value)) => {
                self.value = Some(value);
                seed.deserialize(Value::String(key)).map(Some)
            }
            None => Ok(None),
        }
    }

    fn next_value_seed<V>(&mut self, seed: V) -> Result<V::Value>
    where
        V: de::DeserializeSeed<'de>,
    {
        match self.value.take() {
            Some(value) => seed.deserialize(value),
            None => Err(Error::Message("value is missing".to_string())),
        }
    }
}

/// A libconfig document that tracks top-level formatting.
///
/// `Config` wraps a `Value` and remembers whether the outer group uses
/// implicit format (no braces) or explicit format (`{...}`).
///
/// Create an empty config with [`Config::new`], parse from a string with
/// [`Config::from_str`], or wrap an existing `Value` with `Config::from(value)`.
///
/// `Config` derefs to `Value`, so all `Value` methods (indexing, lookup,
/// set, remove) work directly on a `Config`.
///
/// # Examples
///
/// ```
/// use libconfig::{Config, Value};
///
/// let mut config = Config::new();
/// config.set("name", Value::String("test".into()));
/// config.set("version", Value::Integer(42));
///
/// assert_eq!(config["name"], "test");
/// assert_eq!(config["version"], 42);
///
/// let output = config.to_string().unwrap();
/// assert_eq!(output, "name = \"test\";\nversion = 42;");
/// ```
#[derive(Debug, Clone, PartialEq)]
pub struct Config {
    /// The root value of the configuration
    pub value: Value,
    /// Whether the outer group has explicit braces
    pub explicit_braces: bool,
}

impl Config {
    /// Create a new empty Config with implicit outer group format.
    pub fn new() -> Self {
        Config {
            value: Value::Group(Map::new()),
            explicit_braces: false,
        }
    }

    /// Parse a libconfig string into a `Config`, automatically detecting
    /// whether the input uses an implicit group (no outer braces) or
    /// explicit group (`{...}`).
    ///
    /// # Examples
    ///
    /// ```
    /// use libconfig::Config;
    ///
    /// // Implicit group (no braces)
    /// let config = Config::from_str("a = 1; b = 2;").unwrap();
    /// assert!(!config.explicit_braces);
    /// assert_eq!(config["a"], 1);
    ///
    /// // Explicit group (with braces)
    /// let config = Config::from_str("{ a = 1; b = 2; }").unwrap();
    /// assert!(config.explicit_braces);
    /// assert_eq!(config["a"], 1);
    /// ```
    pub fn from_str(s: &str) -> Result<Config> {
        let trimmed = s.trim_start();
        let explicit_braces = trimmed.starts_with('{');
        let value: Value = crate::from_str(s)?;
        Ok(Config {
            value,
            explicit_braces,
        })
    }

    /// Read and parse a libconfig file into a `Config`, automatically
    /// detecting whether the input uses an implicit or explicit group.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use libconfig::Config;
    ///
    /// let config = Config::from_file("settings.cfg").unwrap();
    /// println!("{}", config["name"]);
    /// ```
    pub fn from_file<P: AsRef<std::path::Path>>(path: P) -> Result<Config> {
        let contents = std::fs::read_to_string(path)
            .map_err(|e| Error::Message(format!("failed to read file: {}", e)))?;
        Config::from_str(&contents)
    }

    /// Serialize this config to a libconfig string, respecting
    /// the `explicit_braces` setting.
    pub fn to_string(&self) -> Result<String> {
        to_string_format_impl(&self.value, 0, self.explicit_braces)
    }
}

impl Default for Config {
    fn default() -> Self {
        Config::new()
    }
}

impl From<Value> for Config {
    fn from(value: Value) -> Self {
        Config {
            value,
            explicit_braces: false,
        }
    }
}

impl std::ops::Deref for Config {
    type Target = Value;

    fn deref(&self) -> &Value {
        &self.value
    }
}

impl std::ops::DerefMut for Config {
    fn deref_mut(&mut self) -> &mut Value {
        &mut self.value
    }
}

impl fmt::Display for Config {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self.to_string() {
            Ok(s) => write!(f, "{}", s),
            Err(e) => write!(f, "<error: {}>", e),
        }
    }
}

impl Serialize for Config {
    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        self.value.serialize(serializer)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::from_str;

    #[test]
    fn test_value_types() {
        let v = Value::Bool(true);
        assert!(v.is_bool());
        assert_eq!(v.as_bool(), Some(true));

        let v = Value::Integer(42);
        assert!(v.is_i32());
        assert_eq!(v.as_i32(), Some(42));

        let v = Value::Float(3.14);
        assert!(v.is_float());
        assert_eq!(v.as_f64(), Some(3.14));

        let v = Value::String("hello".to_string());
        assert!(v.is_string());
        assert_eq!(v.as_str(), Some("hello"));
    }

    #[test]
    fn test_value_indexing() {
        let config = r#"
            {
                name = "Test";
                count = 42;
                items = [1, 2, 3];
            }
        "#;

        let v: Value = from_str(config).unwrap();
        assert_eq!(v["name"], "Test");
        assert_eq!(v["count"], 42);
        assert_eq!(v["items"][0], 1);
        assert_eq!(v["items"][1], 2);
    }

    #[test]
    fn test_value_lookup() {
        let config = r#"
            {
                application = {
                    window = {
                        title = "My App";
                        size = { w = 640; h = 480; };
                    };
                };
            }
        "#;

        let v: Value = from_str(config).unwrap();
        assert_eq!(
            v.lookup("application.window.title")
                .and_then(|v| v.as_str()),
            Some("My App")
        );
        assert_eq!(
            v.lookup("application.window.size")
                .and_then(|v| v.get("w"))
                .and_then(|v| v.as_i32()),
            Some(640)
        );
    }

    #[test]
    fn test_value_lookup_with_array_index() {
        let config = r#"
            {
                name = "Test";
                items = [10, 20, 30];
                nested = {
                    ports = [80, 443];
                };
            }
        "#;

        let v: Value = from_str(config).unwrap();

        // Direct array index
        assert_eq!(v.lookup("items.0").and_then(|v| v.as_i32()), Some(10));
        assert_eq!(v.lookup("items.1").and_then(|v| v.as_i32()), Some(20));
        assert_eq!(v.lookup("items.2").and_then(|v| v.as_i32()), Some(30));

        // Nested group then array index
        assert_eq!(
            v.lookup("nested.ports.0").and_then(|v| v.as_i32()),
            Some(80)
        );
        assert_eq!(
            v.lookup("nested.ports.1").and_then(|v| v.as_i32()),
            Some(443)
        );

        // Out of bounds returns None
        assert!(v.lookup("items.5").is_none());

        // Index on non-array returns None
        assert!(v.lookup("name.0").is_none());

        // Index via [] operator
        assert_eq!(v["items.0"], 10);
        assert_eq!(v["nested.ports.1"], 443);
    }

    #[test]
    fn test_value_comparison() {
        let v = Value::Bool(true);
        assert!(v == true);

        let v = Value::Integer(42);
        assert!(v == 42);

        let v = Value::String("hello".to_string());
        assert!(v == "hello");
    }

    #[test]
    fn test_value_round_trip() {
        let config = r#"
            {
                name = "Test";
                version = 1;
                enabled = true;
                pi = 3.14;
                items = [1, 2, 3];
            }
        "#;

        let v: Value = from_str(config).unwrap();
        let serialized = crate::to_string(&v).unwrap();
        let v2: Value = from_str(&serialized).unwrap();

        assert_eq!(v["name"], v2["name"]);
        assert_eq!(v["version"], v2["version"]);
        assert_eq!(v["enabled"], v2["enabled"]);
    }

    // === Path parsing tests ===

    #[test]
    fn test_parse_path_dotted_keys() {
        let segs = parse_path("a.b.c").unwrap();
        assert_eq!(
            segs,
            vec![
                PathSegment::Key("a"),
                PathSegment::Key("b"),
                PathSegment::Key("c"),
            ]
        );
    }

    #[test]
    fn test_parse_path_bracket_index() {
        let segs = parse_path("items.[0].title").unwrap();
        assert_eq!(
            segs,
            vec![
                PathSegment::Key("items"),
                PathSegment::Index(0),
                PathSegment::Key("title"),
            ]
        );
    }

    #[test]
    fn test_parse_path_bare_numeric() {
        let segs = parse_path("items.0").unwrap();
        assert_eq!(segs, vec![PathSegment::Key("items"), PathSegment::Index(0)]);
    }

    #[test]
    fn test_parse_path_single_segment() {
        assert_eq!(
            parse_path("version").unwrap(),
            vec![PathSegment::Key("version")]
        );
    }

    #[test]
    fn test_parse_path_invalid() {
        assert!(parse_path("").is_none());
        assert!(parse_path("a..b").is_none());
        assert!(parse_path(".a").is_none());
        assert!(parse_path("a.").is_none());
        assert!(parse_path("items.[abc]").is_none());
        assert!(parse_path("items.[-1]").is_none());
        assert!(parse_path("items.[]").is_none());
    }

    // === Bracket notation lookup tests ===

    #[test]
    fn test_lookup_bracket_notation() {
        let config = r#"
            {
                books = (
                    { title = "Treasure Island"; price = 29; },
                    { title = "Snow Crash"; price = 9; }
                );
            }
        "#;
        let v: Value = from_str(config).unwrap();

        // Bracket notation
        assert_eq!(
            v.lookup("books.[0].title").and_then(|v| v.as_str()),
            Some("Treasure Island")
        );
        assert_eq!(
            v.lookup("books.[1].price").and_then(|v| v.as_i32()),
            Some(9)
        );

        // Bare numeric still works
        assert_eq!(
            v.lookup("books.0.title").and_then(|v| v.as_str()),
            Some("Treasure Island")
        );
    }

    #[test]
    fn test_lookup_mut_bracket_notation() {
        let config = r#"{ items = [10, 20, 30]; }"#;
        let mut v: Value = from_str(config).unwrap();

        *v.lookup_mut("items.[1]").unwrap() = Value::Integer(99);
        assert_eq!(v.lookup("items.[1]").unwrap().as_i32(), Some(99));
        assert_eq!(v.lookup("items.1").unwrap().as_i32(), Some(99));
    }

    // === Set tests ===

    #[test]
    fn test_set_existing_key() {
        let mut v: Value = from_str(r#"{ name = "old"; }"#).unwrap();
        assert_eq!(v.set("name", Value::String("new".to_string())), Some(()));
        assert_eq!(v.lookup("name").unwrap().as_str(), Some("new"));
    }

    #[test]
    fn test_set_new_key() {
        let mut v: Value = from_str(r#"{ a = 1; }"#).unwrap();
        assert_eq!(v.set("b", Value::Integer(2)), Some(()));
        assert_eq!(v.lookup("b").unwrap().as_i32(), Some(2));
    }

    #[test]
    fn test_set_creates_intermediate_groups() {
        let mut v = Value::Group(IndexMap::new());
        assert_eq!(v.set("a.b.c", Value::Integer(42)), Some(()));
        assert_eq!(v.lookup("a.b.c").unwrap().as_i32(), Some(42));
        assert!(v.lookup("a").unwrap().is_group());
        assert!(v.lookup("a.b").unwrap().is_group());
    }

    #[test]
    fn test_set_array_element() {
        let mut v: Value = from_str(r#"{ items = [1, 2, 3]; }"#).unwrap();
        assert_eq!(v.set("items.[0]", Value::Integer(99)), Some(()));
        assert_eq!(v.lookup("items.[0]").unwrap().as_i32(), Some(99));
    }

    #[test]
    fn test_set_array_out_of_bounds() {
        let mut v: Value = from_str(r#"{ items = [1, 2]; }"#).unwrap();
        assert_eq!(v.set("items.[5]", Value::Integer(99)), None);
    }

    #[test]
    fn test_set_on_scalar_fails() {
        let mut v: Value = from_str(r#"{ name = "hello"; }"#).unwrap();
        assert_eq!(v.set("name.child", Value::Integer(1)), None);
    }

    #[test]
    fn test_set_deeply_nested() {
        let mut v = Value::Group(IndexMap::new());
        assert_eq!(
            v.set("level1.level2.level3.level4", Value::Bool(true)),
            Some(())
        );
        assert_eq!(
            v.lookup("level1.level2.level3.level4").unwrap().as_bool(),
            Some(true)
        );
    }

    #[test]
    fn test_set_into_list_element_group() {
        let config = r#"
            {
                books = (
                    { title = "Old Title"; }
                );
            }
        "#;
        let mut v: Value = from_str(config).unwrap();
        assert_eq!(
            v.set("books.[0].title", Value::String("New Title".to_string())),
            Some(())
        );
        assert_eq!(
            v.lookup("books.[0].title").unwrap().as_str(),
            Some("New Title")
        );
    }

    // === Remove tests ===

    #[test]
    fn test_remove_group_key() {
        let mut v: Value = from_str(r#"{ a = 1; b = 2; c = 3; }"#).unwrap();
        let removed = v.remove("b");
        assert_eq!(removed, Some(Value::Integer(2)));
        assert!(v.lookup("b").is_none());
        assert_eq!(v.lookup("a").unwrap().as_i32(), Some(1));
        assert_eq!(v.lookup("c").unwrap().as_i32(), Some(3));
    }

    #[test]
    fn test_remove_array_element() {
        let mut v: Value = from_str(r#"{ items = [10, 20, 30]; }"#).unwrap();
        let removed = v.remove("items.[1]");
        assert_eq!(removed, Some(Value::Integer(20)));
        // Elements shift: [10, 30]
        assert_eq!(v.lookup("items.[0]").unwrap().as_i32(), Some(10));
        assert_eq!(v.lookup("items.[1]").unwrap().as_i32(), Some(30));
        assert!(v.lookup("items.[2]").is_none());
    }

    #[test]
    fn test_remove_nested() {
        let config = r#"
            {
                database = {
                    host = "localhost";
                    port = 5432;
                };
            }
        "#;
        let mut v: Value = from_str(config).unwrap();
        let removed = v.remove("database.host");
        assert_eq!(removed, Some(Value::String("localhost".to_string())));
        assert!(v.lookup("database.host").is_none());
        assert_eq!(v.lookup("database.port").unwrap().as_i32(), Some(5432));
    }

    #[test]
    fn test_remove_nonexistent() {
        let mut v: Value = from_str(r#"{ a = 1; }"#).unwrap();
        assert_eq!(v.remove("z"), None);
        assert_eq!(v.remove("a.b"), None);
    }

    #[test]
    fn test_remove_index_out_of_bounds() {
        let mut v: Value = from_str(r#"{ items = [1, 2]; }"#).unwrap();
        assert_eq!(v.remove("items.[5]"), None);
    }

    #[test]
    fn test_remove_entire_subtree() {
        let config = r#"
            {
                app = {
                    window = { title = "hi"; };
                    debug = false;
                };
            }
        "#;
        let mut v: Value = from_str(config).unwrap();
        let removed = v.remove("app.window");
        assert!(removed.unwrap().is_group());
        assert!(v.lookup("app.window").is_none());
        assert_eq!(v.lookup("app.debug").unwrap().as_bool(), Some(false));
    }

    #[test]
    fn test_remove_bare_numeric_index() {
        let mut v: Value = from_str(r#"{ items = [10, 20, 30]; }"#).unwrap();
        let removed = v.remove("items.0");
        assert_eq!(removed, Some(Value::Integer(10)));
        assert_eq!(v.lookup("items.0").unwrap().as_i32(), Some(20));
    }

    // === Ordering and format preservation tests ===

    #[test]
    fn test_ordering_preserved_in_round_trip() {
        let input = r#"{
  first = 1;
  second = 2;
  third = 3;
  fourth = 4;
}"#;
        let v: Value = from_str(input).unwrap();
        let output = Config::from(v.clone()).to_string().unwrap();

        // Parse both and verify key order
        let v_output: Value = from_str(&output).unwrap();
        if let Value::Group(map) = v {
            if let Value::Group(map_output) = v_output {
                let keys1: Vec<&String> = map.keys().collect();
                let keys2: Vec<&String> = map_output.keys().collect();
                assert_eq!(keys1, keys2);
                assert_eq!(keys1, vec!["first", "second", "third", "fourth"]);
            }
        }
    }

    #[test]
    fn test_config_implicit_no_outer_braces() {
        let input = "a = 1;\nb = 2;\nc = 3;";
        let v: Value = from_str(input).unwrap();

        let output = Config::from(v).to_string().unwrap();

        // Implicit config omits outer braces
        assert!(!output.trim_start().starts_with('{'));
        assert!(!output.trim_end().ends_with('}'));

        // Should contain the keys
        assert!(output.contains("a = 1"));
        assert!(output.contains("b = 2"));
        assert!(output.contains("c = 3"));
    }

    #[test]
    fn test_config_explicit_outer_braces() {
        let input = "a = 1;\nb = 2;\nc = 3;";
        let v: Value = from_str(input).unwrap();

        let mut config = Config::from(v);
        config.explicit_braces = true;
        let output = config.to_string().unwrap();

        // Explicit config adds outer braces
        assert!(output.trim_start().starts_with('{'));
        assert!(output.trim_end().ends_with('}'));

        // Should contain the keys
        assert!(output.contains("a = 1"));
        assert!(output.contains("b = 2"));
        assert!(output.contains("c = 3"));
    }

    #[test]
    fn test_config_implicit_vs_explicit() {
        let input = "{\n  a = 1;\n  b = 2;\n  c = 3;\n}";
        let v: Value = from_str(input).unwrap();

        // Config::from produces implicit format
        let output = Config::from(v.clone()).to_string().unwrap();
        assert!(!output.trim_start().starts_with('{'));
        assert!(!output.trim_end().ends_with('}'));

        // Setting explicit_braces produces explicit format
        let mut config = Config::from(v);
        config.explicit_braces = true;
        let output_braces = config.to_string().unwrap();
        assert!(output_braces.trim_start().starts_with('{'));
        assert!(output_braces.trim_end().ends_with('}'));
    }

    #[test]
    fn test_nested_groups_have_braces() {
        let input = r#"{
  outer = 1;
  nested = {
    inner = 2;
  };
}"#;
        let v: Value = from_str(input).unwrap();
        let output = Config::from(v).to_string().unwrap();

        // Outer group should not have braces (implicit format)
        assert!(!output.trim_start().starts_with('{'));

        // Nested groups should still have braces
        assert!(output.contains("nested = {"));

        // Parse and verify structure
        let v2: Value = from_str(&output).unwrap();
        assert_eq!(v2["outer"], 1);
        assert_eq!(v2["nested.inner"], 2);
    }

    #[test]
    fn test_ordering_with_mixed_types() {
        let input = r#"{
  string_first = "hello";
  int_second = 42;
  bool_third = true;
  float_fourth = 3.14;
  array_fifth = [1, 2, 3];
}"#;
        let v: Value = from_str(input).unwrap();

        if let Value::Group(map) = &v {
            let keys: Vec<&String> = map.keys().collect();
            assert_eq!(
                keys,
                vec![
                    "string_first",
                    "int_second",
                    "bool_third",
                    "float_fourth",
                    "array_fifth"
                ]
            );
        }

        let output = Config::from(v).to_string().unwrap();
        let v2: Value = from_str(&output).unwrap();

        // Verify order is preserved after round-trip
        if let Value::Group(map) = &v2 {
            let keys: Vec<&String> = map.keys().collect();
            assert_eq!(
                keys,
                vec![
                    "string_first",
                    "int_second",
                    "bool_third",
                    "float_fourth",
                    "array_fifth"
                ]
            );
        }
    }

    #[test]
    fn test_adding_new_keys_appends_to_end() {
        let input = "a = 1;\nb = 2;";
        let mut v: Value = from_str(input).unwrap();

        // Add a new key
        v.set("c", Value::Integer(3)).unwrap();

        if let Value::Group(map) = &v {
            let keys: Vec<&String> = map.keys().collect();
            assert_eq!(keys, vec!["a", "b", "c"]);
        }

        let output = Config::from(v).to_string().unwrap();

        // Verify new key appears at the end
        let a_pos = output.find("a = 1").unwrap();
        let b_pos = output.find("b = 2").unwrap();
        let c_pos = output.find("c = 3").unwrap();

        assert!(a_pos < b_pos);
        assert!(b_pos < c_pos);
    }

    #[test]
    fn test_implicit_group_round_trip_exact() {
        let input = "name = \"test\";\nversion = 42;";
        let v: Value = from_str(input).unwrap();
        let output = Config::from(v).to_string().unwrap();

        // Output should match input exactly
        assert_eq!(output, input);

        // Round-trip should be stable
        let v2: Value = from_str(&output).unwrap();
        let output2 = Config::from(v2).to_string().unwrap();
        assert_eq!(output, output2);
    }

    #[test]
    fn test_nested_indentation() {
        let input = r#"{
  outer = 1;
  nested = {
    inner = 2;
    deep = {
      value = 3;
    };
  };
  another = 4;
}"#;
        let v: Value = from_str(input).unwrap();
        let output = Config::from(v).to_string().unwrap();

        // Top-level keys have no indentation (implicit outer group)
        assert!(output.contains("outer = 1"));
        assert!(output.contains("nested = {"));
        // Nested keys get 2-space indentation
        assert!(output.contains("  inner = 2"));
        assert!(output.contains("  deep = {"));
        // Deeply nested keys get 4-space indentation
        assert!(output.contains("    value = 3"));

        // Verify it can be parsed back
        let v2: Value = from_str(&output).unwrap();
        assert_eq!(v2["outer"], 1);
        assert_eq!(v2["nested.inner"], 2);
        assert_eq!(v2["nested.deep.value"], 3);
        assert_eq!(v2["another"], 4);
    }

    #[test]
    fn test_implicit_group_with_nested_explicit_groups() {
        let input = r#"top_level = 1;
nested = {
  inner = 2;
};
also_top = 3;"#;
        let v: Value = from_str(input).unwrap();
        let output = Config::from(v).to_string().unwrap();

        // Top level should not have braces (implicit format)
        assert!(!output.trim().starts_with('{'));

        // Nested group should have braces
        assert!(output.contains("nested = {"));
        assert!(output.contains("  inner = 2"));

        // Parse and verify
        let v2: Value = from_str(&output).unwrap();
        assert_eq!(v2["top_level"], 1);
        assert_eq!(v2["nested.inner"], 2);
        assert_eq!(v2["also_top"], 3);
    }

    #[test]
    fn test_deeply_nested_groups() {
        let input = r#"{
  level1 = {
    level2 = {
      level3 = {
        value = 42;
      };
    };
  };
}"#;
        let v: Value = from_str(input).unwrap();
        let output = Config::from(v).to_string().unwrap();

        // Top-level is implicit (no braces, no indent)
        // Each nested level adds 2-space indentation
        assert!(output.contains("level1 = {"));
        assert!(output.contains("  level2 = {"));
        assert!(output.contains("    level3 = {"));
        assert!(output.contains("      value = 42"));
    }

    // === Config wrapper tests ===

    #[test]
    fn test_config_implicit_round_trip() {
        let input = "name = \"test\";\nversion = 42;";
        let config = Config::from_str(input).unwrap();

        assert!(!config.explicit_braces);
        assert_eq!(config["name"], "test");
        assert_eq!(config["version"], 42);

        let output = config.to_string().unwrap();
        assert_eq!(output, input);
    }

    #[test]
    fn test_config_explicit_round_trip() {
        let input = "{\n  name = \"test\";\n  version = 42;\n}";
        let config = Config::from_str(input).unwrap();

        assert!(config.explicit_braces);
        assert_eq!(config["name"], "test");

        let output = config.to_string().unwrap();
        assert!(output.starts_with('{'));
        assert!(output.ends_with('}'));
    }

    #[test]
    fn test_config_deref_lookup() {
        let config = Config::from_str("a = 1; b = { c = 2; };").unwrap();

        // Deref allows Value methods directly
        assert_eq!(config.lookup("b.c").unwrap().as_i32(), Some(2));
        assert!(config.is_group());
    }

    #[test]
    fn test_config_deref_mut() {
        let mut config = Config::from_str("a = 1; b = 2;").unwrap();

        config.set("c", Value::Integer(3)).unwrap();
        assert_eq!(config["c"], 3);

        let output = config.to_string().unwrap();
        assert!(output.contains("c = 3"));
    }

    #[test]
    fn test_config_display() {
        let config = Config::from_str("x = 10; y = 20;").unwrap();
        let displayed = format!("{}", config);
        assert!(displayed.contains("x = 10"));
        assert!(displayed.contains("y = 20"));
        assert!(!displayed.starts_with('{'));
    }

    #[test]
    fn test_config_new_empty() {
        let mut config = Config::new();
        assert!(!config.explicit_braces);
        assert!(config.is_group());

        config.set("key", Value::String("val".to_string())).unwrap();
        let output = config.to_string().unwrap();
        assert_eq!(output, "key = \"val\";");
    }

    #[test]
    fn test_config_from_value() {
        let mut map = Map::new();
        map.insert("key".to_string(), Value::String("val".to_string()));
        let config = Config::from(Value::Group(map));

        assert!(!config.explicit_braces);
        let output = config.to_string().unwrap();
        assert_eq!(output, "key = \"val\";");
    }

    #[test]
    fn test_config_from_value_explicit() {
        let mut map = Map::new();
        map.insert("key".to_string(), Value::String("val".to_string()));
        let mut config = Config::from(Value::Group(map));
        config.explicit_braces = true;

        assert!(config.explicit_braces);
        let output = config.to_string().unwrap();
        assert!(output.starts_with('{'));
        assert!(output.contains("key = \"val\""));
    }

    #[test]
    fn test_config_default() {
        let config = Config::default();
        assert!(!config.explicit_braces);
        assert!(config.is_group());
        assert_eq!(config.as_group().unwrap().len(), 0);
    }

    #[test]
    fn test_config_serialize() {
        let config = Config::from_str("a = 1; b = 2;").unwrap();
        // Serialize through serde (always produces braces)
        let serde_output = crate::to_string(&config).unwrap();
        assert!(serde_output.starts_with('{'));

        // Config::to_string preserves format
        let format_output = config.to_string().unwrap();
        assert!(!format_output.starts_with('{'));
    }
}