hongdown/

config.rs

// SPDX-FileCopyrightText: 2025 Hong Minhee <https://hongminhee.org/>
// SPDX-License-Identifier: GPL-3.0-or-later
//! Configuration file support for Hongdown.
//!
//! This module provides functionality for loading and parsing configuration
//! files (`.hongdown.toml`) that control the formatter's behavior.

use std::collections::HashMap;
use std::path::{Path, PathBuf};

use serde::Deserialize;

/// The default configuration file name.
pub const CONFIG_FILE_NAME: &str = ".hongdown.toml";

/// Default value for `git_aware` (true).
fn default_git_aware() -> bool {
    true
}

/// Configuration for the Hongdown formatter.
#[derive(Debug, Clone, Deserialize, PartialEq)]
#[serde(default)]
pub struct Config {
    /// Skip inheriting from parent configurations (default: false).
    /// When true, only this config file and Hongdown's defaults are used.
    #[serde(default)]
    pub no_inherit: bool,

    /// Maximum line width for wrapping (default: 80).
    pub line_width: LineWidth,

    /// Glob patterns for files to include (default: empty, meaning all files
    /// must be specified on command line).
    pub include: Vec<String>,

    /// Glob patterns for files to exclude (default: empty).
    pub exclude: Vec<String>,

    /// Respect `.gitignore` files and skip `.git` directory (default: true).
    #[serde(default = "default_git_aware")]
    pub git_aware: bool,

    /// Heading formatting options.
    pub heading: HeadingConfig,

    /// Unordered list formatting options.
    pub unordered_list: UnorderedListConfig,

    /// Ordered list formatting options.
    pub ordered_list: OrderedListConfig,

    /// Code block formatting options.
    pub code_block: CodeBlockConfig,

    /// Thematic break (horizontal rule) formatting options.
    pub thematic_break: ThematicBreakConfig,

    /// Punctuation transformation options (SmartyPants-style).
    pub punctuation: PunctuationConfig,
}

impl Default for Config {
    fn default() -> Self {
        Self {
            no_inherit: false,
            line_width: LineWidth::default(),
            include: Vec::new(),
            exclude: Vec::new(),
            git_aware: true,
            heading: HeadingConfig::default(),
            unordered_list: UnorderedListConfig::default(),
            ordered_list: OrderedListConfig::default(),
            code_block: CodeBlockConfig::default(),
            thematic_break: ThematicBreakConfig::default(),
            punctuation: PunctuationConfig::default(),
        }
    }
}

/// A layer of configuration that may have some fields unset.
///
/// Used for merging multiple configuration sources with field-level overriding.
/// This allows cascading configurations where later configs only override
/// specific fields they define, preserving other fields from parent configs.
#[derive(Debug, Clone, Deserialize, PartialEq, Default)]
#[serde(default)]
pub struct ConfigLayer {
    /// Skip inheriting from parent configurations (default: false).
    #[serde(default)]
    pub no_inherit: bool,

    /// Maximum line width for wrapping.
    pub line_width: Option<LineWidth>,

    /// Glob patterns for files to include.
    pub include: Option<Vec<String>>,

    /// Glob patterns for files to exclude.
    pub exclude: Option<Vec<String>>,

    /// Respect `.gitignore` files and skip `.git` directory.
    pub git_aware: Option<bool>,

    /// Heading formatting options.
    pub heading: Option<HeadingConfig>,

    /// Unordered list formatting options.
    pub unordered_list: Option<UnorderedListConfig>,

    /// Ordered list formatting options.
    pub ordered_list: Option<OrderedListConfig>,

    /// Code block formatting options.
    pub code_block: Option<CodeBlockConfig>,

    /// Thematic break (horizontal rule) formatting options.
    pub thematic_break: Option<ThematicBreakConfig>,

    /// Punctuation transformation options (SmartyPants-style).
    pub punctuation: Option<PunctuationConfig>,
}

impl ConfigLayer {
    /// Load a ConfigLayer from a TOML file.
    ///
    /// Returns an error if the file cannot be read or the TOML is invalid.
    pub fn from_file(path: &Path) -> Result<Self, ConfigError> {
        let content =
            std::fs::read_to_string(path).map_err(|e| ConfigError::Io(path.to_path_buf(), e))?;
        toml::from_str(&content).map_err(|e| ConfigError::Parse(path.to_path_buf(), e))
    }

    /// Merge this layer on top of a base Config.
    ///
    /// Fields set in this layer (Some(value)) override the corresponding
    /// fields in the base config. Fields that are None preserve the base
    /// config's values.
    pub fn merge_over(self, mut base: Config) -> Config {
        // Always update no_inherit from the layer
        base.no_inherit = self.no_inherit;

        if let Some(line_width) = self.line_width {
            base.line_width = line_width;
        }
        if let Some(include) = self.include {
            base.include = include;
        }
        if let Some(exclude) = self.exclude {
            base.exclude = exclude;
        }
        if let Some(git_aware) = self.git_aware {
            base.git_aware = git_aware;
        }
        if let Some(heading) = self.heading {
            base.heading = heading;
        }
        if let Some(unordered_list) = self.unordered_list {
            base.unordered_list = unordered_list;
        }
        if let Some(ordered_list) = self.ordered_list {
            base.ordered_list = ordered_list;
        }
        if let Some(code_block) = self.code_block {
            base.code_block = code_block;
        }
        if let Some(thematic_break) = self.thematic_break {
            base.thematic_break = thematic_break;
        }
        if let Some(punctuation) = self.punctuation {
            base.punctuation = punctuation;
        }
        base
    }
}

/// Heading formatting options.
#[derive(Debug, Clone, Deserialize, PartialEq)]
#[serde(default)]
pub struct HeadingConfig {
    /// Use `===` underline for h1 (default: true).
    pub setext_h1: bool,

    /// Use `---` underline for h2 (default: true).
    pub setext_h2: bool,

    /// Convert headings to sentence case (default: false).
    pub sentence_case: bool,

    /// Additional proper nouns to preserve (case-sensitive).
    /// These are merged with built-in proper nouns.
    pub proper_nouns: Vec<String>,

    /// Words to treat as common nouns (case-sensitive).
    /// These are excluded from built-in proper nouns.
    /// Useful for words like "Go" which can be either a programming language
    /// or a common verb depending on context.
    pub common_nouns: Vec<String>,
}

impl Default for HeadingConfig {
    fn default() -> Self {
        Self {
            setext_h1: true,
            setext_h2: true,
            sentence_case: false,
            proper_nouns: Vec::new(),
            common_nouns: Vec::new(),
        }
    }
}

/// Marker character for unordered lists.
#[derive(Debug, Clone, Copy, Deserialize, PartialEq, Eq, Default)]
pub enum UnorderedMarker {
    /// Hyphen marker (`-`)
    #[default]
    #[serde(rename = "-")]
    Hyphen,
    /// Asterisk marker (`*`)
    #[serde(rename = "*")]
    Asterisk,
    /// Plus marker (`+`)
    #[serde(rename = "+")]
    Plus,
}

impl UnorderedMarker {
    /// Get the character representation of this marker.
    pub fn as_char(self) -> char {
        match self {
            Self::Hyphen => '-',
            Self::Asterisk => '*',
            Self::Plus => '+',
        }
    }
}

/// Leading spaces before a list marker or thematic break (0-3).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct LeadingSpaces(usize);

impl LeadingSpaces {
    /// Maximum allowed leading spaces (CommonMark requirement).
    pub const MAX: usize = 3;

    /// Create a new LeadingSpaces.
    ///
    /// Returns an error if the value is greater than 3.
    pub fn new(value: usize) -> Result<Self, String> {
        if value > Self::MAX {
            Err(format!(
                "leading_spaces must be at most {}, got {}.",
                Self::MAX,
                value
            ))
        } else {
            Ok(Self(value))
        }
    }

    /// Get the inner value.
    pub fn get(self) -> usize {
        self.0
    }
}

impl Default for LeadingSpaces {
    fn default() -> Self {
        Self(1)
    }
}

impl<'de> serde::Deserialize<'de> for LeadingSpaces {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        let value = usize::deserialize(deserializer)?;
        Self::new(value).map_err(serde::de::Error::custom)
    }
}

/// Trailing spaces after a list marker (0-3).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct TrailingSpaces(usize);

impl TrailingSpaces {
    /// Maximum allowed trailing spaces (CommonMark requirement).
    pub const MAX: usize = 3;

    /// Create a new TrailingSpaces.
    ///
    /// Returns an error if the value is greater than 3.
    pub fn new(value: usize) -> Result<Self, String> {
        if value > Self::MAX {
            Err(format!(
                "trailing_spaces must be at most {}, got {}.",
                Self::MAX,
                value
            ))
        } else {
            Ok(Self(value))
        }
    }

    /// Get the inner value.
    pub fn get(self) -> usize {
        self.0
    }
}

impl Default for TrailingSpaces {
    fn default() -> Self {
        Self(2)
    }
}

impl<'de> serde::Deserialize<'de> for TrailingSpaces {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        let value = usize::deserialize(deserializer)?;
        Self::new(value).map_err(serde::de::Error::custom)
    }
}

/// Indentation width for nested list items (must be at least 1).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct IndentWidth(usize);

impl IndentWidth {
    /// Minimum allowed indent width.
    pub const MIN: usize = 1;

    /// Create a new IndentWidth.
    ///
    /// Returns an error if the value is less than 1.
    pub fn new(value: usize) -> Result<Self, String> {
        if value < Self::MIN {
            Err(format!(
                "indent_width must be at least {}, got {}.",
                Self::MIN,
                value
            ))
        } else {
            Ok(Self(value))
        }
    }

    /// Get the inner value.
    pub fn get(self) -> usize {
        self.0
    }
}

impl Default for IndentWidth {
    fn default() -> Self {
        Self(4)
    }
}

impl<'de> serde::Deserialize<'de> for IndentWidth {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        let value = usize::deserialize(deserializer)?;
        Self::new(value).map_err(serde::de::Error::custom)
    }
}

/// Maximum line width for text wrapping (must be at least 8).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct LineWidth(usize);

impl LineWidth {
    /// Minimum allowed line width.
    pub const MIN: usize = 8;

    /// Recommended minimum line width.
    pub const RECOMMENDED_MIN: usize = 40;

    /// Create a new LineWidth.
    ///
    /// Returns an error if the value is less than 8.
    pub fn new(value: usize) -> Result<Self, String> {
        if value < Self::MIN {
            Err(format!(
                "line_width must be at least {}, got {}.",
                Self::MIN,
                value
            ))
        } else {
            Ok(Self(value))
        }
    }

    /// Get the inner value.
    pub fn get(self) -> usize {
        self.0
    }

    /// Check if the line width is below the recommended minimum.
    pub fn is_below_recommended(self) -> bool {
        self.0 < Self::RECOMMENDED_MIN
    }
}

impl Default for LineWidth {
    fn default() -> Self {
        Self(80)
    }
}

impl<'de> serde::Deserialize<'de> for LineWidth {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        let value = usize::deserialize(deserializer)?;
        Self::new(value).map_err(serde::de::Error::custom)
    }
}

/// Unordered list formatting options.
#[derive(Debug, Clone, Deserialize, PartialEq, Default)]
#[serde(default)]
pub struct UnorderedListConfig {
    /// Marker character: `-`, `*`, or `+` (default: `-`).
    pub unordered_marker: UnorderedMarker,

    /// Spaces before the marker (default: 1).
    pub leading_spaces: LeadingSpaces,

    /// Spaces after the marker (default: 2).
    pub trailing_spaces: TrailingSpaces,

    /// Indentation width for nested items (default: 4).
    pub indent_width: IndentWidth,
}

/// Marker character for ordered lists.
#[derive(Debug, Clone, Copy, Deserialize, PartialEq, Eq, Default)]
pub enum OrderedMarker {
    /// Period marker (`.`) - `1.`, `2.`, etc.
    #[default]
    #[serde(rename = ".")]
    Period,
    /// Parenthesis marker (`)`) - `1)`, `2)`, etc.
    #[serde(rename = ")")]
    Parenthesis,
}

impl OrderedMarker {
    /// Get the character representation of this marker.
    pub fn as_char(self) -> char {
        match self {
            Self::Period => '.',
            Self::Parenthesis => ')',
        }
    }
}

/// Padding style for ordered list numbers.
#[derive(Debug, Clone, Copy, Deserialize, PartialEq, Default)]
#[serde(rename_all = "lowercase")]
pub enum OrderedListPad {
    /// Pad before the number (default): `  1.`, `  2.`, ..., ` 10.`
    #[default]
    Start,
    /// Pad after the number: `1. `, `2. `, ..., `10.`
    End,
}

/// Ordered list formatting options.
#[derive(Debug, Clone, Deserialize, PartialEq)]
#[serde(default)]
pub struct OrderedListConfig {
    /// Marker style at odd nesting levels: `.` for `1.` (default: `.`).
    pub odd_level_marker: OrderedMarker,

    /// Marker style at even nesting levels: `)` for `1)` (default: `)`).
    pub even_level_marker: OrderedMarker,

    /// Padding style for aligning numbers of different widths (default: `start`).
    pub pad: OrderedListPad,

    /// Indentation width for nested ordered list items (default: 4).
    pub indent_width: IndentWidth,
}

impl Default for OrderedListConfig {
    fn default() -> Self {
        Self {
            odd_level_marker: OrderedMarker::default(),
            even_level_marker: OrderedMarker::Parenthesis,
            pad: OrderedListPad::Start,
            indent_width: IndentWidth::default(),
        }
    }
}

/// Default timeout for external formatters in seconds.
fn default_formatter_timeout() -> u64 {
    5
}

/// External formatter configuration for a single language.
///
/// Can be specified in two formats:
/// - Simple: `["command", "arg1", "arg2"]`
/// - Full: `{ command = ["command", "arg1"], timeout = 10 }`
#[derive(Debug, Clone, Deserialize, PartialEq)]
#[serde(untagged)]
pub enum FormatterConfig {
    /// Simple array format: `["deno", "fmt", "-"]`
    Simple(Vec<String>),
    /// Full format with command and options.
    Full {
        /// Command and arguments as a vector.
        command: Vec<String>,
        /// Timeout in seconds (default: 5).
        #[serde(default = "default_formatter_timeout")]
        timeout: u64,
    },
}

impl FormatterConfig {
    /// Get the command as a slice.
    pub fn command(&self) -> &[String] {
        match self {
            FormatterConfig::Simple(cmd) => cmd,
            FormatterConfig::Full { command, .. } => command,
        }
    }

    /// Get the timeout in seconds.
    pub fn timeout(&self) -> u64 {
        match self {
            FormatterConfig::Simple(_) => default_formatter_timeout(),
            FormatterConfig::Full { timeout, .. } => *timeout,
        }
    }

    /// Validate the configuration.
    ///
    /// Returns an error message if the configuration is invalid.
    pub fn validate(&self) -> Result<(), String> {
        if self.command().is_empty() {
            return Err("formatter command cannot be empty".to_string());
        }
        Ok(())
    }
}

/// Fence character for code blocks.
#[derive(Debug, Clone, Copy, Deserialize, PartialEq, Eq, Default)]
pub enum FenceChar {
    /// Tilde fence (`~`)
    #[default]
    #[serde(rename = "~")]
    Tilde,
    /// Backtick fence (`` ` ``)
    #[serde(rename = "`")]
    Backtick,
}

impl FenceChar {
    /// Get the character representation of this fence character.
    pub fn as_char(self) -> char {
        match self {
            Self::Tilde => '~',
            Self::Backtick => '`',
        }
    }
}

/// Minimum fence length for code blocks (must be at least 3).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct MinFenceLength(usize);

impl MinFenceLength {
    /// Minimum allowed fence length (CommonMark requirement).
    pub const MIN: usize = 3;

    /// Create a new MinFenceLength.
    ///
    /// Returns an error if the value is less than 3.
    pub fn new(value: usize) -> Result<Self, String> {
        if value < Self::MIN {
            Err(format!(
                "min_fence_length must be at least {}, got {}.",
                Self::MIN,
                value
            ))
        } else {
            Ok(Self(value))
        }
    }

    /// Get the inner value.
    pub fn get(self) -> usize {
        self.0
    }
}

impl Default for MinFenceLength {
    fn default() -> Self {
        Self(4)
    }
}

impl<'de> serde::Deserialize<'de> for MinFenceLength {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        let value = usize::deserialize(deserializer)?;
        Self::new(value).map_err(serde::de::Error::custom)
    }
}

/// Code block formatting options.
#[derive(Debug, Clone, Deserialize, PartialEq)]
#[serde(default)]
pub struct CodeBlockConfig {
    /// Fence character: `~` or `` ` `` (default: `~`).
    pub fence_char: FenceChar,

    /// Minimum fence length (default: 4).
    pub min_fence_length: MinFenceLength,

    /// Add space between fence and language identifier (default: true).
    pub space_after_fence: bool,

    /// Default language identifier for code blocks without one (default: empty).
    /// When empty, code blocks without a language identifier remain without one.
    /// Set to e.g. "text" to add a default language identifier.
    pub default_language: String,

    /// External formatters for code blocks by language.
    ///
    /// Key: language identifier (exact match only).
    /// Value: formatter configuration.
    pub formatters: HashMap<String, FormatterConfig>,
}

impl Default for CodeBlockConfig {
    fn default() -> Self {
        Self {
            fence_char: FenceChar::default(),
            min_fence_length: MinFenceLength::default(),
            space_after_fence: true,
            default_language: String::new(),
            formatters: HashMap::new(),
        }
    }
}

/// Thematic break style string (must be a valid CommonMark thematic break pattern).
///
/// A valid thematic break consists of:
/// - At least 3 of the same character: `*`, `-`, or `_`
/// - Optional spaces between the characters
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ThematicBreakStyle(String);

impl ThematicBreakStyle {
    /// Minimum number of marker characters required.
    pub const MIN_MARKERS: usize = 3;

    /// Create a new ThematicBreakStyle.
    ///
    /// Returns an error if the style is not a valid CommonMark thematic break pattern.
    pub fn new(style: String) -> Result<Self, String> {
        // Validate the thematic break pattern according to CommonMark spec:
        // - Must contain at least 3 of the same character (*, -, or _)
        // - Can have spaces between characters
        // - No other characters allowed (except spaces)

        let trimmed = style.trim();
        if trimmed.is_empty() {
            return Err("thematic_break style cannot be empty.".to_string());
        }

        // Count each marker type
        let mut asterisk_count = 0;
        let mut hyphen_count = 0;
        let mut underscore_count = 0;
        let mut has_other = false;

        for ch in trimmed.chars() {
            match ch {
                '*' => asterisk_count += 1,
                '-' => hyphen_count += 1,
                '_' => underscore_count += 1,
                ' ' | '\t' => {} // Whitespace is allowed
                _ => {
                    has_other = true;
                    break;
                }
            }
        }

        if has_other {
            return Err(format!(
                "thematic_break style must only contain *, -, or _ (with optional spaces), got {:?}.",
                style
            ));
        }

        // Must have at least 3 of exactly one marker type
        let marker_counts = [
            (asterisk_count, '*'),
            (hyphen_count, '-'),
            (underscore_count, '_'),
        ];

        let valid_markers: Vec<_> = marker_counts
            .iter()
            .filter(|(count, _)| *count >= Self::MIN_MARKERS)
            .collect();

        if valid_markers.is_empty() {
            return Err(format!(
                "thematic_break style must contain at least {} of the same marker (*, -, or _), got {:?}.",
                Self::MIN_MARKERS,
                style
            ));
        }

        if valid_markers.len() > 1 {
            return Err(format!(
                "thematic_break style must use only one type of marker (*, -, or _), got {:?}.",
                style
            ));
        }

        Ok(Self(style))
    }

    /// Get the inner value.
    pub fn as_str(&self) -> &str {
        &self.0
    }
}

impl Default for ThematicBreakStyle {
    fn default() -> Self {
        Self(
            "- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -".to_string(),
        )
    }
}

impl<'de> serde::Deserialize<'de> for ThematicBreakStyle {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        let value = String::deserialize(deserializer)?;
        Self::new(value).map_err(serde::de::Error::custom)
    }
}

/// Thematic break (horizontal rule) formatting options.
#[derive(Debug, Clone, Deserialize, PartialEq)]
#[serde(default)]
pub struct ThematicBreakConfig {
    /// The style string for thematic breaks (default: `*  *  *`).
    pub style: ThematicBreakStyle,

    /// Number of leading spaces before the thematic break (0-3, default: 3).
    /// CommonMark allows 0-3 leading spaces for thematic breaks.
    pub leading_spaces: LeadingSpaces,
}

impl Default for ThematicBreakConfig {
    fn default() -> Self {
        Self {
            style: ThematicBreakStyle::default(),
            leading_spaces: LeadingSpaces::new(3).unwrap(),
        }
    }
}

/// Dash pattern for en-dash or em-dash transformation.
/// Must be a non-empty string of valid characters.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct DashPattern(String);

impl DashPattern {
    /// Create a new DashPattern.
    ///
    /// Returns an error if the pattern is empty or contains invalid characters.
    pub fn new(pattern: String) -> Result<Self, String> {
        if pattern.is_empty() {
            return Err("dash pattern cannot be empty.".to_string());
        }

        // Check for non-printable or whitespace characters
        if pattern.chars().any(|c| !c.is_ascii_graphic()) {
            return Err(format!(
                "dash pattern must only contain printable ASCII characters (no whitespace), got {:?}.",
                pattern
            ));
        }

        Ok(Self(pattern))
    }

    /// Get the inner value.
    pub fn as_str(&self) -> &str {
        &self.0
    }
}

impl<'de> serde::Deserialize<'de> for DashPattern {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        let value = String::deserialize(deserializer)?;
        Self::new(value).map_err(serde::de::Error::custom)
    }
}

/// Dash transformation setting.
/// Can be `false` (disabled) or a string pattern to match.
#[derive(Debug, Clone, PartialEq, Default)]
pub enum DashSetting {
    /// Dash transformation is disabled.
    #[default]
    Disabled,
    /// Transform the given pattern to a dash character.
    Pattern(DashPattern),
}

impl<'de> Deserialize<'de> for DashSetting {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        use serde::de::{self, Visitor};

        struct DashSettingVisitor;

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

            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
                formatter.write_str("false or a string pattern")
            }

            fn visit_bool<E>(self, value: bool) -> Result<DashSetting, E>
            where
                E: de::Error,
            {
                if value {
                    Err(de::Error::custom(
                        "expected false or a string pattern, got true",
                    ))
                } else {
                    Ok(DashSetting::Disabled)
                }
            }

            fn visit_str<E>(self, value: &str) -> Result<DashSetting, E>
            where
                E: de::Error,
            {
                DashPattern::new(value.to_string())
                    .map(DashSetting::Pattern)
                    .map_err(de::Error::custom)
            }

            fn visit_string<E>(self, value: String) -> Result<DashSetting, E>
            where
                E: de::Error,
            {
                DashPattern::new(value)
                    .map(DashSetting::Pattern)
                    .map_err(de::Error::custom)
            }
        }

        deserializer.deserialize_any(DashSettingVisitor)
    }
}

/// Punctuation transformation options (SmartyPants-style).
#[derive(Debug, Clone, Deserialize, PartialEq)]
#[serde(default)]
pub struct PunctuationConfig {
    /// Convert straight double quotes to curly quotes (default: true).
    /// `"text"` becomes `"text"` (U+201C and U+201D).
    pub curly_double_quotes: bool,

    /// Convert straight single quotes to curly quotes (default: true).
    /// `'text'` becomes `'text'` (U+2018 and U+2019).
    pub curly_single_quotes: bool,

    /// Convert straight apostrophes to curly apostrophes (default: false).
    /// `it's` becomes `it's` (U+2019).
    pub curly_apostrophes: bool,

    /// Convert three dots to ellipsis character (default: true).
    /// `...` becomes `…` (U+2026).
    pub ellipsis: bool,

    /// Convert a pattern to en-dash (default: disabled).
    /// Set to a string like `"--"` to enable.
    /// The pattern is replaced with `–` (U+2013).
    pub en_dash: DashSetting,

    /// Convert a pattern to em-dash (default: `"--"`).
    /// Set to `false` to disable, or a string like `"---"` for a different pattern.
    /// The pattern is replaced with `—` (U+2014).
    pub em_dash: DashSetting,
}

impl Default for PunctuationConfig {
    fn default() -> Self {
        Self {
            curly_double_quotes: true,
            curly_single_quotes: true,
            curly_apostrophes: false,
            ellipsis: true,
            en_dash: DashSetting::Disabled,
            em_dash: DashSetting::Pattern(DashPattern::new("--".to_string()).unwrap()),
        }
    }
}

impl Config {
    /// Parse a configuration from a TOML string.
    pub fn from_toml(toml_str: &str) -> Result<Self, toml::de::Error> {
        toml::from_str(toml_str)
    }

    /// Load configuration from a file.
    pub fn from_file(path: &Path) -> Result<Self, ConfigError> {
        let content =
            std::fs::read_to_string(path).map_err(|e| ConfigError::Io(path.to_path_buf(), e))?;
        Self::from_toml(&content).map_err(|e| ConfigError::Parse(path.to_path_buf(), e))
    }

    /// Discover and load configuration by searching up the directory tree.
    ///
    /// Starting from `start_dir`, searches for `.hongdown.toml` in each parent
    /// directory until the filesystem root is reached. Returns `None` if no
    /// configuration file is found.
    pub fn discover(start_dir: &Path) -> Result<Option<(PathBuf, Self)>, ConfigError> {
        let mut current = start_dir.to_path_buf();
        loop {
            let config_path = current.join(CONFIG_FILE_NAME);
            if config_path.exists() {
                let config = Self::from_file(&config_path)?;
                return Ok(Some((config_path, config)));
            }
            if !current.pop() {
                break;
            }
        }
        Ok(None)
    }

    /// Load cascading configuration from all sources.
    ///
    /// Returns the merged configuration and the path of the project config
    /// (if found). Configurations are loaded and merged in this order:
    /// 1. System config (`/etc/hongdown/config.toml`)
    /// 2. User legacy config (`~/.hongdown.toml`)
    /// 3. User XDG config (`$XDG_CONFIG_HOME/hongdown/config.toml`)
    /// 4. Project config (`.hongdown.toml` in `start_dir` or parent directories)
    ///
    /// If the project config has `no_inherit = true`, all parent configs are
    /// ignored.
    pub fn load_cascading(start_dir: &Path) -> Result<(Self, Option<PathBuf>), ConfigError> {
        let mut layers = Vec::new();
        let mut project_config_path = None;

        // 1. Try system-wide config: /etc/hongdown/config.toml
        if let Some(layer) = Self::load_system_config()? {
            layers.push(layer);
        }

        // 2. Try user legacy config: ~/.hongdown.toml
        if let Some(layer) = Self::load_user_legacy_config()? {
            layers.push(layer);
        }

        // 3. Try XDG user config: $XDG_CONFIG_HOME/hongdown/config.toml
        if let Some(layer) = Self::load_user_xdg_config()? {
            layers.push(layer);
        }

        // 4. Try project config: search upward from start_dir
        if let Some((path, layer)) = Self::discover_project_config(start_dir)? {
            project_config_path = Some(path);

            // If no_inherit is true, skip all parent layers
            if layer.no_inherit {
                layers.clear();
            }

            layers.push(layer);
        }

        // Merge all layers, starting from Config::default()
        let mut config = Self::default();
        for layer in layers {
            config = layer.merge_over(config);
        }

        Ok((config, project_config_path))
    }

    /// Load system-wide config from /etc/hongdown/config.toml.
    fn load_system_config() -> Result<Option<ConfigLayer>, ConfigError> {
        Self::try_load_layer(Path::new("/etc/hongdown/config.toml"))
    }

    /// Load user legacy config from ~/.hongdown.toml.
    fn load_user_legacy_config() -> Result<Option<ConfigLayer>, ConfigError> {
        if let Some(home) = dirs::home_dir() {
            Self::try_load_layer(&home.join(".hongdown.toml"))
        } else {
            Ok(None)
        }
    }

    /// Load user XDG config from $XDG_CONFIG_HOME/hongdown/config.toml.
    fn load_user_xdg_config() -> Result<Option<ConfigLayer>, ConfigError> {
        if let Some(config_dir) = dirs::config_dir() {
            Self::try_load_layer(&config_dir.join("hongdown/config.toml"))
        } else {
            Ok(None)
        }
    }

    /// Discover project config by searching upward from start_dir.
    fn discover_project_config(
        start_dir: &Path,
    ) -> Result<Option<(PathBuf, ConfigLayer)>, ConfigError> {
        let mut current = start_dir.to_path_buf();
        loop {
            let config_path = current.join(CONFIG_FILE_NAME);
            if config_path.exists() {
                let layer = ConfigLayer::from_file(&config_path)?;
                return Ok(Some((config_path, layer)));
            }
            if !current.pop() {
                break;
            }
        }
        Ok(None)
    }

    /// Try to load a config layer from a path. Returns None if file doesn't exist.
    fn try_load_layer(path: &Path) -> Result<Option<ConfigLayer>, ConfigError> {
        if !path.exists() {
            return Ok(None);
        }
        ConfigLayer::from_file(path).map(Some)
    }

    /// Collect files matching the include patterns, excluding those matching
    /// exclude patterns.
    ///
    /// The `base_dir` is used as the starting point for glob pattern matching.
    /// Returns an empty list if no include patterns are configured.
    pub fn collect_files(&self, base_dir: &Path) -> Result<Vec<PathBuf>, ConfigError> {
        use ignore::WalkBuilder;
        use ignore::overrides::OverrideBuilder;

        if self.include.is_empty() {
            return Ok(Vec::new());
        }

        // Build override patterns: include patterns are whitelist,
        // exclude patterns are prefixed with ! to negate them
        let mut override_builder = OverrideBuilder::new(base_dir);

        // Add include patterns
        for pattern in &self.include {
            override_builder.add(pattern).map_err(ConfigError::Ignore)?;
        }

        // Add exclude patterns with ! prefix (negation)
        for pattern in &self.exclude {
            override_builder
                .add(&format!("!{}", pattern))
                .map_err(ConfigError::Ignore)?;
        }

        let overrides = override_builder.build().map_err(ConfigError::Ignore)?;

        // Build walker with overrides
        // This efficiently skips directories that don't match patterns
        let walker = WalkBuilder::new(base_dir)
            .hidden(false) // Don't automatically ignore hidden files
            .git_ignore(self.git_aware) // Respect .gitignore if git_aware is enabled
            .git_global(false) // Don't use global gitignore (for consistency)
            .git_exclude(self.git_aware) // Respect .git/info/exclude if git_aware is enabled
            .overrides(overrides)
            .build();

        // Collect matching files
        let mut files = Vec::new();
        for entry in walker {
            let entry = entry.map_err(ConfigError::Ignore)?;
            let path = entry.path();
            if path.is_file() {
                files.push(path.to_path_buf());
            }
        }

        // Sort for consistent ordering
        files.sort();

        Ok(files)
    }
}

/// Errors that can occur when loading configuration.
#[derive(Debug)]
pub enum ConfigError {
    /// I/O error reading the configuration file.
    Io(PathBuf, std::io::Error),
    /// Error parsing the TOML configuration.
    Parse(PathBuf, toml::de::Error),
    /// Error parsing a glob pattern.
    Glob(String, glob::PatternError),
    /// I/O error during glob iteration.
    GlobIo(glob::GlobError),
    /// Error from ignore crate (file traversal).
    Ignore(ignore::Error),
}

impl std::fmt::Display for ConfigError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            ConfigError::Io(path, err) => {
                write!(f, "failed to read {}: {}", path.display(), err)
            }
            ConfigError::Parse(path, err) => {
                write!(f, "failed to parse {}: {}", path.display(), err)
            }
            ConfigError::Glob(pattern, err) => {
                write!(f, "invalid glob pattern '{}': {}", pattern, err)
            }
            ConfigError::GlobIo(err) => {
                write!(f, "error reading file: {}", err)
            }
            ConfigError::Ignore(err) => {
                write!(f, "error during file traversal: {}", err)
            }
        }
    }
}

impl std::error::Error for ConfigError {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match self {
            ConfigError::Io(_, err) => Some(err),
            ConfigError::Parse(_, err) => Some(err),
            ConfigError::Glob(_, err) => Some(err),
            ConfigError::GlobIo(err) => Some(err),
            ConfigError::Ignore(err) => Some(err),
        }
    }
}

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

    #[test]
    fn test_default_config() {
        let config = Config::default();
        assert_eq!(config.line_width.get(), 80);
        assert!(config.git_aware);
        assert!(config.heading.setext_h1);
        assert!(config.heading.setext_h2);
        assert_eq!(
            config.unordered_list.unordered_marker,
            UnorderedMarker::Hyphen
        );
        assert_eq!(config.unordered_list.leading_spaces.get(), 1);
        assert_eq!(config.unordered_list.trailing_spaces.get(), 2);
        assert_eq!(config.unordered_list.indent_width.get(), 4);
        assert_eq!(config.ordered_list.odd_level_marker, OrderedMarker::Period);
        assert_eq!(
            config.ordered_list.even_level_marker,
            OrderedMarker::Parenthesis
        );
        assert_eq!(config.ordered_list.pad, OrderedListPad::Start);
        assert_eq!(config.ordered_list.indent_width.get(), 4);
        assert_eq!(config.code_block.fence_char, FenceChar::Tilde);
        assert_eq!(config.code_block.min_fence_length.get(), 4);
        assert!(config.code_block.space_after_fence);
        assert_eq!(config.code_block.default_language, "");
        assert_eq!(
            config.thematic_break.style.as_str(),
            "- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -"
        );
        assert_eq!(config.thematic_break.leading_spaces.get(), 3);
    }

    #[test]
    fn test_parse_empty_toml() {
        let config = Config::from_toml("").unwrap();
        assert_eq!(config, Config::default());
    }

    #[test]
    fn test_parse_line_width() {
        let config = Config::from_toml("line_width = 100").unwrap();
        assert_eq!(config.line_width.get(), 100);
    }

    #[test]
    fn test_parse_heading_config() {
        let config = Config::from_toml(
            r#"
[heading]
setext_h1 = false
setext_h2 = false
"#,
        )
        .unwrap();
        assert!(!config.heading.setext_h1);
        assert!(!config.heading.setext_h2);
    }

    #[test]
    fn test_parse_heading_sentence_case() {
        let config = Config::from_toml(
            r#"
[heading]
sentence_case = true
"#,
        )
        .unwrap();
        assert!(config.heading.sentence_case);
    }

    #[test]
    fn test_parse_heading_proper_nouns() {
        let config = Config::from_toml(
            r#"
[heading]
proper_nouns = ["Hongdown", "MyCompany", "MyProduct"]
"#,
        )
        .unwrap();
        assert_eq!(
            config.heading.proper_nouns,
            vec!["Hongdown", "MyCompany", "MyProduct"]
        );
    }

    #[test]
    fn test_parse_heading_sentence_case_with_proper_nouns() {
        let config = Config::from_toml(
            r#"
[heading]
sentence_case = true
proper_nouns = ["Hongdown", "MyAPI"]
"#,
        )
        .unwrap();
        assert!(config.heading.sentence_case);
        assert_eq!(config.heading.proper_nouns, vec!["Hongdown", "MyAPI"]);
    }

    #[test]
    fn test_parse_heading_common_nouns() {
        let config = Config::from_toml(
            r#"
[heading]
common_nouns = ["Go", "Swift"]
"#,
        )
        .unwrap();
        assert_eq!(config.heading.common_nouns, vec!["Go", "Swift"]);
    }

    #[test]
    fn test_parse_heading_with_proper_and_common_nouns() {
        let config = Config::from_toml(
            r#"
[heading]
sentence_case = true
proper_nouns = ["MyAPI"]
common_nouns = ["Go"]
"#,
        )
        .unwrap();
        assert!(config.heading.sentence_case);
        assert_eq!(config.heading.proper_nouns, vec!["MyAPI"]);
        assert_eq!(config.heading.common_nouns, vec!["Go"]);
    }

    #[test]
    fn test_parse_unordered_list_config() {
        let config = Config::from_toml(
            r#"
[unordered_list]
unordered_marker = "*"
leading_spaces = 0
trailing_spaces = 1
indent_width = 2
"#,
        )
        .unwrap();
        assert_eq!(
            config.unordered_list.unordered_marker,
            UnorderedMarker::Asterisk
        );
        assert_eq!(config.unordered_list.leading_spaces.get(), 0);
        assert_eq!(config.unordered_list.trailing_spaces.get(), 1);
        assert_eq!(config.unordered_list.indent_width.get(), 2);
    }

    #[test]
    fn test_parse_ordered_list_config() {
        let config = Config::from_toml(
            r#"
[ordered_list]
odd_level_marker = ")"
even_level_marker = "."
"#,
        )
        .unwrap();
        assert_eq!(
            config.ordered_list.odd_level_marker,
            OrderedMarker::Parenthesis
        );
        assert_eq!(config.ordered_list.even_level_marker, OrderedMarker::Period);
        assert_eq!(config.ordered_list.pad, OrderedListPad::Start); // default
    }

    #[test]
    fn test_parse_ordered_list_pad_end() {
        let config = Config::from_toml(
            r#"
[ordered_list]
pad = "end"
"#,
        )
        .unwrap();
        assert_eq!(config.ordered_list.pad, OrderedListPad::End);
    }

    #[test]
    fn test_parse_ordered_list_pad_start() {
        let config = Config::from_toml(
            r#"
[ordered_list]
pad = "start"
"#,
        )
        .unwrap();
        assert_eq!(config.ordered_list.pad, OrderedListPad::Start);
    }

    #[test]
    fn test_parse_code_block_config() {
        let config = Config::from_toml(
            r#"
[code_block]
fence_char = "`"
min_fence_length = 3
space_after_fence = false
"#,
        )
        .unwrap();
        assert_eq!(config.code_block.fence_char, FenceChar::Backtick);
        assert_eq!(config.code_block.min_fence_length.get(), 3);
        assert!(!config.code_block.space_after_fence);
        assert_eq!(config.code_block.default_language, ""); // Default is empty
    }

    #[test]
    fn test_parse_code_block_default_language() {
        let config = Config::from_toml(
            r#"
[code_block]
default_language = "text"
"#,
        )
        .unwrap();
        assert_eq!(config.code_block.default_language, "text");
    }

    #[test]
    fn test_parse_full_config() {
        let config = Config::from_toml(
            r#"
line_width = 80

[heading]
setext_h1 = true
setext_h2 = true

[unordered_list]
unordered_marker = "-"
leading_spaces = 1
trailing_spaces = 2
indent_width = 4

[ordered_list]
odd_level_marker = "."
even_level_marker = ")"

[code_block]
fence_char = "~"
min_fence_length = 4
space_after_fence = true

[thematic_break]
style = "- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -"
leading_spaces = 3
"#,
        )
        .unwrap();
        assert_eq!(config, Config::default());
    }

    #[test]
    fn test_parse_thematic_break_config() {
        let config = Config::from_toml(
            r#"
[thematic_break]
style = "---"
"#,
        )
        .unwrap();
        assert_eq!(config.thematic_break.style.as_str(), "---");
    }

    #[test]
    fn test_parse_invalid_toml() {
        let result = Config::from_toml("line_width = \"not a number\"");
        assert!(result.is_err());
    }

    #[test]
    fn test_discover_config_in_parent_dir() {
        let temp_dir = std::env::temp_dir().join("hongdown_test_parent");
        let _ = std::fs::remove_dir_all(&temp_dir);
        let sub_dir = temp_dir.join("subdir").join("nested");
        std::fs::create_dir_all(&sub_dir).unwrap();
        let config_path = temp_dir.join(CONFIG_FILE_NAME);
        std::fs::write(&config_path, "line_width = 90").unwrap();

        let result = Config::discover(&sub_dir).unwrap();
        assert!(result.is_some());
        let (path, config) = result.unwrap();
        assert_eq!(path, config_path);
        assert_eq!(config.line_width.get(), 90);

        let _ = std::fs::remove_dir_all(&temp_dir);
    }

    #[test]
    fn test_default_include_exclude() {
        let config = Config::default();
        assert!(config.include.is_empty());
        assert!(config.exclude.is_empty());
    }

    #[test]
    fn test_parse_include_patterns() {
        let config = Config::from_toml(
            r#"
include = ["*.md", "docs/**/*.md"]
"#,
        )
        .unwrap();
        assert_eq!(config.include, vec!["*.md", "docs/**/*.md"]);
    }

    #[test]
    fn test_parse_exclude_patterns() {
        let config = Config::from_toml(
            r#"
exclude = ["node_modules/**", "target/**"]
"#,
        )
        .unwrap();
        assert_eq!(config.exclude, vec!["node_modules/**", "target/**"]);
    }

    #[test]
    fn test_parse_include_and_exclude() {
        let config = Config::from_toml(
            r#"
include = ["**/*.md"]
exclude = ["vendor/**"]
"#,
        )
        .unwrap();
        assert_eq!(config.include, vec!["**/*.md"]);
        assert_eq!(config.exclude, vec!["vendor/**"]);
    }

    #[test]
    fn test_collect_files_with_include() {
        let temp_dir = std::env::temp_dir().join("hongdown_test_collect");
        let _ = std::fs::remove_dir_all(&temp_dir);
        std::fs::create_dir_all(&temp_dir).unwrap();
        std::fs::write(temp_dir.join("README.md"), "# Test").unwrap();
        std::fs::write(temp_dir.join("CHANGELOG.md"), "# Changes").unwrap();
        std::fs::write(temp_dir.join("main.rs"), "fn main() {}").unwrap();

        let config = Config::from_toml(r#"include = ["*.md"]"#).unwrap();
        let files = config.collect_files(&temp_dir).unwrap();

        assert_eq!(files.len(), 2);
        assert!(files.iter().any(|p| p.ends_with("README.md")));
        assert!(files.iter().any(|p| p.ends_with("CHANGELOG.md")));

        let _ = std::fs::remove_dir_all(&temp_dir);
    }

    #[test]
    fn test_collect_files_with_exclude() {
        let temp_dir = std::env::temp_dir().join("hongdown_test_exclude");
        let _ = std::fs::remove_dir_all(&temp_dir);
        std::fs::create_dir_all(&temp_dir).unwrap();
        std::fs::create_dir_all(temp_dir.join("vendor")).unwrap();
        std::fs::write(temp_dir.join("README.md"), "# Test").unwrap();
        std::fs::write(temp_dir.join("vendor").join("lib.md"), "# Lib").unwrap();

        let config = Config::from_toml(
            r#"
include = ["**/*.md"]
exclude = ["vendor/**"]
"#,
        )
        .unwrap();
        let files = config.collect_files(&temp_dir).unwrap();

        assert_eq!(files.len(), 1);
        assert!(files[0].ends_with("README.md"));

        let _ = std::fs::remove_dir_all(&temp_dir);
    }

    #[test]
    fn test_collect_files_empty_include() {
        let temp_dir = std::env::temp_dir().join("hongdown_test_empty");
        let _ = std::fs::remove_dir_all(&temp_dir);
        std::fs::create_dir_all(&temp_dir).unwrap();
        std::fs::write(temp_dir.join("README.md"), "# Test").unwrap();

        let config = Config::default();
        let files = config.collect_files(&temp_dir).unwrap();

        assert!(files.is_empty());

        let _ = std::fs::remove_dir_all(&temp_dir);
    }

    #[test]
    fn test_default_punctuation_config() {
        let config = PunctuationConfig::default();
        assert!(config.curly_double_quotes);
        assert!(config.curly_single_quotes);
        assert!(!config.curly_apostrophes);
        assert!(config.ellipsis);
        assert_eq!(config.en_dash, DashSetting::Disabled);
        assert_eq!(
            config.em_dash,
            DashSetting::Pattern(DashPattern::new("--".to_string()).unwrap())
        );
    }

    #[test]
    fn test_parse_punctuation_config_all_options() {
        let config = Config::from_toml(
            r#"
[punctuation]
curly_double_quotes = false
curly_single_quotes = false
curly_apostrophes = true
ellipsis = false
en_dash = "--"
em_dash = "---"
"#,
        )
        .unwrap();
        assert!(!config.punctuation.curly_double_quotes);
        assert!(!config.punctuation.curly_single_quotes);
        assert!(config.punctuation.curly_apostrophes);
        assert!(!config.punctuation.ellipsis);
        assert_eq!(
            config.punctuation.en_dash,
            DashSetting::Pattern(DashPattern::new("--".to_string()).unwrap())
        );
        assert_eq!(
            config.punctuation.em_dash,
            DashSetting::Pattern(DashPattern::new("---".to_string()).unwrap())
        );
    }

    #[test]
    fn test_parse_dash_setting_disabled() {
        let config = Config::from_toml(
            r#"
[punctuation]
em_dash = false
"#,
        )
        .unwrap();
        assert_eq!(config.punctuation.em_dash, DashSetting::Disabled);
    }

    #[test]
    fn test_parse_dash_setting_pattern() {
        let config = Config::from_toml(
            r#"
[punctuation]
en_dash = "---"
"#,
        )
        .unwrap();
        assert_eq!(
            config.punctuation.en_dash,
            DashSetting::Pattern(DashPattern::new("---".to_string()).unwrap())
        );
    }

    #[test]
    fn test_punctuation_config_in_full_config() {
        let config = Config::from_toml(
            r#"
line_width = 100

[punctuation]
curly_double_quotes = true
em_dash = "--"
"#,
        )
        .unwrap();
        assert_eq!(config.line_width.get(), 100);
        assert!(config.punctuation.curly_double_quotes);
        assert_eq!(
            config.punctuation.em_dash,
            DashSetting::Pattern(DashPattern::new("--".to_string()).unwrap())
        );
    }

    #[test]
    fn test_default_code_block_formatters() {
        let config = Config::default();
        assert!(config.code_block.formatters.is_empty());
    }

    #[test]
    fn test_parse_formatter_simple() {
        let config = Config::from_toml(
            r#"
[code_block.formatters]
javascript = ["deno", "fmt", "-"]
"#,
        )
        .unwrap();
        let formatter = config.code_block.formatters.get("javascript").unwrap();
        assert_eq!(formatter.command(), &["deno", "fmt", "-"]);
        assert_eq!(formatter.timeout(), 5);
    }

    #[test]
    fn test_parse_formatter_full() {
        let config = Config::from_toml(
            r#"
[code_block.formatters.python]
command = ["black", "-"]
timeout = 10
"#,
        )
        .unwrap();
        let formatter = config.code_block.formatters.get("python").unwrap();
        assert_eq!(formatter.command(), &["black", "-"]);
        assert_eq!(formatter.timeout(), 10);
    }

    #[test]
    fn test_parse_formatter_full_default_timeout() {
        let config = Config::from_toml(
            r#"
[code_block.formatters.rust]
command = ["rustfmt"]
"#,
        )
        .unwrap();
        let formatter = config.code_block.formatters.get("rust").unwrap();
        assert_eq!(formatter.command(), &["rustfmt"]);
        assert_eq!(formatter.timeout(), 5);
    }

    #[test]
    fn test_parse_multiple_formatters() {
        let config = Config::from_toml(
            r#"
[code_block.formatters]
javascript = ["deno", "fmt", "-"]
typescript = ["deno", "fmt", "-"]

[code_block.formatters.python]
command = ["black", "-"]
timeout = 10
"#,
        )
        .unwrap();
        assert_eq!(config.code_block.formatters.len(), 3);
        assert!(config.code_block.formatters.contains_key("javascript"));
        assert!(config.code_block.formatters.contains_key("typescript"));
        assert!(config.code_block.formatters.contains_key("python"));
    }

    #[test]
    fn test_formatter_empty_command_validation() {
        let config = Config::from_toml(
            r#"
[code_block.formatters]
javascript = []
"#,
        )
        .unwrap();
        assert!(
            config
                .code_block
                .formatters
                .get("javascript")
                .unwrap()
                .validate()
                .is_err()
        );
    }

    #[test]
    fn test_formatter_valid_command_validation() {
        let config = Config::from_toml(
            r#"
[code_block.formatters]
javascript = ["deno", "fmt", "-"]
"#,
        )
        .unwrap();
        assert!(
            config
                .code_block
                .formatters
                .get("javascript")
                .unwrap()
                .validate()
                .is_ok()
        );
    }
}

#[cfg(test)]
mod unordered_marker_tests {
    use super::*;

    #[test]
    fn test_unordered_marker_default() {
        let marker = UnorderedMarker::default();
        assert_eq!(marker, UnorderedMarker::Hyphen);
        assert_eq!(marker.as_char(), '-');
    }

    #[test]
    fn test_unordered_marker_hyphen() {
        let config = Config::from_toml(
            r#"
[unordered_list]
unordered_marker = "-"
"#,
        )
        .unwrap();
        assert_eq!(
            config.unordered_list.unordered_marker,
            UnorderedMarker::Hyphen
        );
        assert_eq!(config.unordered_list.unordered_marker.as_char(), '-');
    }

    #[test]
    fn test_unordered_marker_asterisk() {
        let config = Config::from_toml(
            r#"
[unordered_list]
unordered_marker = "*"
"#,
        )
        .unwrap();
        assert_eq!(
            config.unordered_list.unordered_marker,
            UnorderedMarker::Asterisk
        );
        assert_eq!(config.unordered_list.unordered_marker.as_char(), '*');
    }

    #[test]
    fn test_unordered_marker_plus() {
        let config = Config::from_toml(
            r#"
[unordered_list]
unordered_marker = "+"
"#,
        )
        .unwrap();
        assert_eq!(
            config.unordered_list.unordered_marker,
            UnorderedMarker::Plus
        );
        assert_eq!(config.unordered_list.unordered_marker.as_char(), '+');
    }

    #[test]
    fn test_unordered_marker_invalid_period() {
        let result = Config::from_toml(
            r#"
[unordered_list]
unordered_marker = "."
"#,
        );
        assert!(result.is_err());
        let err_msg = result.unwrap_err().to_string();
        assert!(err_msg.contains("unordered_marker"));
    }

    #[test]
    fn test_unordered_marker_invalid_letter() {
        let result = Config::from_toml(
            r#"
[unordered_list]
unordered_marker = "x"
"#,
        );
        assert!(result.is_err());
    }

    #[test]
    fn test_unordered_marker_invalid_number() {
        let result = Config::from_toml(
            r#"
[unordered_list]
unordered_marker = "1"
"#,
        );
        assert!(result.is_err());
    }

    #[test]
    fn test_unordered_marker_invalid_empty() {
        let result = Config::from_toml(
            r#"
[unordered_list]
unordered_marker = ""
"#,
        );
        assert!(result.is_err());
    }
}

#[cfg(test)]
mod ordered_marker_tests {
    use super::*;

    #[test]
    fn test_ordered_marker_default() {
        let marker = OrderedMarker::default();
        assert_eq!(marker, OrderedMarker::Period);
        assert_eq!(marker.as_char(), '.');
    }

    #[test]
    fn test_ordered_marker_period() {
        let config = Config::from_toml(
            r#"
[ordered_list]
odd_level_marker = "."
"#,
        )
        .unwrap();
        assert_eq!(config.ordered_list.odd_level_marker, OrderedMarker::Period);
        assert_eq!(config.ordered_list.odd_level_marker.as_char(), '.');
    }

    #[test]
    fn test_ordered_marker_parenthesis() {
        let config = Config::from_toml(
            r#"
[ordered_list]
even_level_marker = ")"
"#,
        )
        .unwrap();
        assert_eq!(
            config.ordered_list.even_level_marker,
            OrderedMarker::Parenthesis
        );
        assert_eq!(config.ordered_list.even_level_marker.as_char(), ')');
    }

    #[test]
    fn test_ordered_marker_invalid_hyphen() {
        let result = Config::from_toml(
            r#"
[ordered_list]
odd_level_marker = "-"
"#,
        );
        assert!(result.is_err());
        let err_msg = result.unwrap_err().to_string();
        assert!(err_msg.contains("odd_level_marker"));
    }

    #[test]
    fn test_ordered_marker_invalid_asterisk() {
        let result = Config::from_toml(
            r#"
[ordered_list]
even_level_marker = "*"
"#,
        );
        assert!(result.is_err());
    }

    #[test]
    fn test_ordered_marker_invalid_letter() {
        let result = Config::from_toml(
            r#"
[ordered_list]
odd_level_marker = "a"
"#,
        );
        assert!(result.is_err());
    }

    #[test]
    fn test_ordered_marker_invalid_empty() {
        let result = Config::from_toml(
            r#"
[ordered_list]
odd_level_marker = ""
"#,
        );
        assert!(result.is_err());
    }
}

#[cfg(test)]
mod fence_char_tests {
    use super::*;

    #[test]
    fn test_fence_char_default_is_tilde() {
        assert_eq!(FenceChar::default(), FenceChar::Tilde);
    }

    #[test]
    fn test_fence_char_as_char() {
        assert_eq!(FenceChar::Tilde.as_char(), '~');
        assert_eq!(FenceChar::Backtick.as_char(), '`');
    }

    #[test]
    fn test_fence_char_parse_tilde() {
        let config = Config::from_toml(
            r#"
[code_block]
fence_char = "~"
"#,
        )
        .unwrap();
        assert_eq!(config.code_block.fence_char, FenceChar::Tilde);
    }

    #[test]
    fn test_fence_char_parse_backtick() {
        let config = Config::from_toml(
            r#"
[code_block]
fence_char = "`"
"#,
        )
        .unwrap();
        assert_eq!(config.code_block.fence_char, FenceChar::Backtick);
    }

    #[test]
    fn test_fence_char_invalid_char() {
        let result = Config::from_toml(
            r##"
[code_block]
fence_char = "#"
"##,
        );
        assert!(result.is_err());
    }

    #[test]
    fn test_fence_char_invalid_empty() {
        let result = Config::from_toml(
            r#"
[code_block]
fence_char = ""
"#,
        );
        assert!(result.is_err());
    }
}

#[cfg(test)]
mod min_fence_length_tests {
    use super::*;

    #[test]
    fn test_min_fence_length_default() {
        assert_eq!(MinFenceLength::default().get(), 4);
    }

    #[test]
    fn test_min_fence_length_valid() {
        assert_eq!(MinFenceLength::new(3).unwrap().get(), 3);
        assert_eq!(MinFenceLength::new(4).unwrap().get(), 4);
        assert_eq!(MinFenceLength::new(10).unwrap().get(), 10);
    }

    #[test]
    fn test_min_fence_length_too_small() {
        assert!(MinFenceLength::new(0).is_err());
        assert!(MinFenceLength::new(1).is_err());
        assert!(MinFenceLength::new(2).is_err());
    }

    #[test]
    fn test_min_fence_length_parse_valid() {
        let config = Config::from_toml(
            r#"
[code_block]
min_fence_length = 3
"#,
        )
        .unwrap();
        assert_eq!(config.code_block.min_fence_length.get(), 3);
    }

    #[test]
    fn test_min_fence_length_parse_invalid() {
        let result = Config::from_toml(
            r#"
[code_block]
min_fence_length = 2
"#,
        );
        assert!(result.is_err());
    }

    #[test]
    fn test_min_fence_length_parse_zero() {
        let result = Config::from_toml(
            r#"
[code_block]
min_fence_length = 0
"#,
        );
        assert!(result.is_err());
    }
}

#[cfg(test)]
mod line_width_tests {
    use super::*;

    #[test]
    fn test_line_width_default() {
        assert_eq!(LineWidth::default().get(), 80);
    }

    #[test]
    fn test_line_width_valid() {
        assert_eq!(LineWidth::new(8).unwrap().get(), 8);
        assert_eq!(LineWidth::new(40).unwrap().get(), 40);
        assert_eq!(LineWidth::new(80).unwrap().get(), 80);
        assert_eq!(LineWidth::new(120).unwrap().get(), 120);
    }

    #[test]
    fn test_line_width_below_recommended() {
        assert!(LineWidth::new(8).unwrap().is_below_recommended());
        assert!(LineWidth::new(39).unwrap().is_below_recommended());
        assert!(!LineWidth::new(40).unwrap().is_below_recommended());
        assert!(!LineWidth::new(80).unwrap().is_below_recommended());
    }

    #[test]
    fn test_line_width_invalid() {
        assert!(LineWidth::new(0).is_err());
        assert!(LineWidth::new(7).is_err());
        assert_eq!(
            LineWidth::new(5).unwrap_err(),
            "line_width must be at least 8, got 5."
        );
    }

    #[test]
    fn test_line_width_parse_valid() {
        let config = Config::from_toml("line_width = 100").unwrap();
        assert_eq!(config.line_width.get(), 100);
    }

    #[test]
    fn test_line_width_parse_invalid() {
        let result = Config::from_toml("line_width = 5");
        assert!(result.is_err());
        let err = result.unwrap_err().to_string();
        assert!(err.contains("line_width must be at least 8"));
    }
}

#[cfg(test)]
mod thematic_break_style_tests {
    use super::*;

    #[test]
    fn test_thematic_break_style_default() {
        let style = ThematicBreakStyle::default();
        assert_eq!(
            style.as_str(),
            "- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -"
        );
    }

    #[test]
    fn test_thematic_break_style_valid_hyphens() {
        assert!(ThematicBreakStyle::new("---".to_string()).is_ok());
        assert!(ThematicBreakStyle::new("- - -".to_string()).is_ok());
        assert!(ThematicBreakStyle::new("-----".to_string()).is_ok());
        assert_eq!(
            ThematicBreakStyle::new("---".to_string()).unwrap().as_str(),
            "---"
        );
    }

    #[test]
    fn test_thematic_break_style_valid_asterisks() {
        assert!(ThematicBreakStyle::new("***".to_string()).is_ok());
        assert!(ThematicBreakStyle::new("* * *".to_string()).is_ok());
        assert!(ThematicBreakStyle::new("*****".to_string()).is_ok());
    }

    #[test]
    fn test_thematic_break_style_valid_underscores() {
        assert!(ThematicBreakStyle::new("___".to_string()).is_ok());
        assert!(ThematicBreakStyle::new("_ _ _".to_string()).is_ok());
        assert!(ThematicBreakStyle::new("_____".to_string()).is_ok());
    }

    #[test]
    fn test_thematic_break_style_empty() {
        let result = ThematicBreakStyle::new("".to_string());
        assert!(result.is_err());
        assert_eq!(result.unwrap_err(), "thematic_break style cannot be empty.");
    }

    #[test]
    fn test_thematic_break_style_too_few_markers() {
        assert!(ThematicBreakStyle::new("--".to_string()).is_err());
        assert!(ThematicBreakStyle::new("**".to_string()).is_err());
        assert!(ThematicBreakStyle::new("__".to_string()).is_err());
        let result = ThematicBreakStyle::new("--".to_string());
        assert!(
            result
                .unwrap_err()
                .contains("must contain at least 3 of the same marker")
        );
    }

    #[test]
    fn test_thematic_break_style_mixed_markers() {
        let result = ThematicBreakStyle::new("---***".to_string());
        assert!(result.is_err());
        assert!(result.unwrap_err().contains("only one type of marker"));
    }

    #[test]
    fn test_thematic_break_style_invalid_characters() {
        let result = ThematicBreakStyle::new("---abc".to_string());
        assert!(result.is_err());
        assert!(result.unwrap_err().contains("must only contain *, -, or _"));
    }

    #[test]
    fn test_thematic_break_style_parse_valid() {
        let config = Config::from_toml(
            r#"
[thematic_break]
style = "***"
"#,
        )
        .unwrap();
        assert_eq!(config.thematic_break.style.as_str(), "***");
    }

    #[test]
    fn test_thematic_break_style_parse_invalid() {
        let result = Config::from_toml(
            r#"
[thematic_break]
style = "--"
"#,
        );
        assert!(result.is_err());
        let err = result.unwrap_err().to_string();
        assert!(err.contains("must contain at least 3"));
    }
}

#[cfg(test)]
mod dash_pattern_tests {
    use super::*;

    #[test]
    fn test_dash_pattern_valid() {
        assert!(DashPattern::new("--".to_string()).is_ok());
        assert!(DashPattern::new("---".to_string()).is_ok());
        assert!(DashPattern::new("-".to_string()).is_ok());
        assert_eq!(DashPattern::new("--".to_string()).unwrap().as_str(), "--");
    }

    #[test]
    fn test_dash_pattern_empty() {
        let result = DashPattern::new("".to_string());
        assert!(result.is_err());
        assert_eq!(result.unwrap_err(), "dash pattern cannot be empty.");
    }

    #[test]
    fn test_dash_pattern_with_whitespace() {
        // Patterns cannot contain whitespace
        assert!(DashPattern::new("- -".to_string()).is_err());
        assert!(DashPattern::new(" --".to_string()).is_err());
        assert!(DashPattern::new("-- ".to_string()).is_err());
        let result = DashPattern::new("- -".to_string());
        assert!(
            result
                .unwrap_err()
                .contains("must only contain printable ASCII characters")
        );
    }

    #[test]
    fn test_dash_pattern_parse_valid() {
        let config = Config::from_toml(
            r#"
[punctuation]
em_dash = "--"
"#,
        )
        .unwrap();
        if let DashSetting::Pattern(p) = &config.punctuation.em_dash {
            assert_eq!(p.as_str(), "--");
        } else {
            panic!("Expected Pattern");
        }
    }

    #[test]
    fn test_dash_pattern_parse_invalid() {
        let result = Config::from_toml(
            r#"
[punctuation]
em_dash = ""
"#,
        );
        assert!(result.is_err());
        let err = result.unwrap_err().to_string();
        assert!(err.contains("dash pattern cannot be empty"));
    }
}

#[cfg(test)]
mod leading_spaces_tests {
    use super::*;

    #[test]
    fn test_leading_spaces_default() {
        assert_eq!(LeadingSpaces::default().get(), 1);
    }

    #[test]
    fn test_leading_spaces_valid() {
        assert_eq!(LeadingSpaces::new(0).unwrap().get(), 0);
        assert_eq!(LeadingSpaces::new(1).unwrap().get(), 1);
        assert_eq!(LeadingSpaces::new(2).unwrap().get(), 2);
        assert_eq!(LeadingSpaces::new(3).unwrap().get(), 3);
    }

    #[test]
    fn test_leading_spaces_invalid() {
        assert!(LeadingSpaces::new(4).is_err());
        assert!(LeadingSpaces::new(5).is_err());
        assert_eq!(
            LeadingSpaces::new(4).unwrap_err(),
            "leading_spaces must be at most 3, got 4."
        );
    }

    #[test]
    fn test_leading_spaces_parse_valid() {
        let config = Config::from_toml(
            r#"
[unordered_list]
leading_spaces = 2
"#,
        )
        .unwrap();
        assert_eq!(config.unordered_list.leading_spaces.get(), 2);
    }

    #[test]
    fn test_leading_spaces_parse_invalid() {
        let result = Config::from_toml(
            r#"
[unordered_list]
leading_spaces = 5
"#,
        );
        assert!(result.is_err());
        let err = result.unwrap_err().to_string();
        assert!(err.contains("leading_spaces must be at most 3"));
    }
}

#[cfg(test)]
mod trailing_spaces_tests {
    use super::*;

    #[test]
    fn test_trailing_spaces_default() {
        assert_eq!(TrailingSpaces::default().get(), 2);
    }

    #[test]
    fn test_trailing_spaces_valid() {
        assert_eq!(TrailingSpaces::new(0).unwrap().get(), 0);
        assert_eq!(TrailingSpaces::new(1).unwrap().get(), 1);
        assert_eq!(TrailingSpaces::new(2).unwrap().get(), 2);
        assert_eq!(TrailingSpaces::new(3).unwrap().get(), 3);
    }

    #[test]
    fn test_trailing_spaces_invalid() {
        assert!(TrailingSpaces::new(4).is_err());
        assert!(TrailingSpaces::new(5).is_err());
        assert_eq!(
            TrailingSpaces::new(4).unwrap_err(),
            "trailing_spaces must be at most 3, got 4."
        );
    }

    #[test]
    fn test_trailing_spaces_parse_valid() {
        let config = Config::from_toml(
            r#"
[unordered_list]
trailing_spaces = 1
"#,
        )
        .unwrap();
        assert_eq!(config.unordered_list.trailing_spaces.get(), 1);
    }

    #[test]
    fn test_trailing_spaces_parse_invalid() {
        let result = Config::from_toml(
            r#"
[unordered_list]
trailing_spaces = 4
"#,
        );
        assert!(result.is_err());
        let err = result.unwrap_err().to_string();
        assert!(err.contains("trailing_spaces must be at most 3"));
    }
}

#[cfg(test)]
mod indent_width_tests {
    use super::*;

    #[test]
    fn test_indent_width_default() {
        assert_eq!(IndentWidth::default().get(), 4);
    }

    #[test]
    fn test_indent_width_valid() {
        assert_eq!(IndentWidth::new(1).unwrap().get(), 1);
        assert_eq!(IndentWidth::new(2).unwrap().get(), 2);
        assert_eq!(IndentWidth::new(4).unwrap().get(), 4);
        assert_eq!(IndentWidth::new(8).unwrap().get(), 8);
    }

    #[test]
    fn test_indent_width_invalid() {
        assert!(IndentWidth::new(0).is_err());
        assert_eq!(
            IndentWidth::new(0).unwrap_err(),
            "indent_width must be at least 1, got 0."
        );
    }

    #[test]
    fn test_indent_width_parse_valid() {
        let config = Config::from_toml(
            r#"
[unordered_list]
indent_width = 2
"#,
        )
        .unwrap();
        assert_eq!(config.unordered_list.indent_width.get(), 2);
    }

    #[test]
    fn test_indent_width_parse_invalid() {
        let result = Config::from_toml(
            r#"
[unordered_list]
indent_width = 0
"#,
        );
        assert!(result.is_err());
        let err = result.unwrap_err().to_string();
        assert!(err.contains("indent_width must be at least 1"));
    }
}

#[cfg(test)]
mod config_layer_tests {
    use super::*;
    use tempfile::TempDir;

    #[test]
    fn test_config_layer_from_file_empty() {
        let temp_dir = TempDir::new().unwrap();
        let config_path = temp_dir.path().join(".hongdown.toml");
        std::fs::write(&config_path, "").unwrap();

        let layer = ConfigLayer::from_file(&config_path).unwrap();
        assert_eq!(layer, ConfigLayer::default());
    }

    #[test]
    fn test_config_layer_from_file_partial() {
        let temp_dir = TempDir::new().unwrap();
        let config_path = temp_dir.path().join(".hongdown.toml");
        std::fs::write(
            &config_path,
            r#"
line_width = 100
git_aware = false
"#,
        )
        .unwrap();

        let layer = ConfigLayer::from_file(&config_path).unwrap();
        assert_eq!(layer.line_width, Some(LineWidth::new(100).unwrap()));
        assert_eq!(layer.git_aware, Some(false));
        assert_eq!(layer.include, None);
        assert_eq!(layer.heading, None);
    }

    #[test]
    fn test_config_layer_from_file_no_inherit() {
        let temp_dir = TempDir::new().unwrap();
        let config_path = temp_dir.path().join(".hongdown.toml");
        std::fs::write(
            &config_path,
            r#"
no_inherit = true
line_width = 100
"#,
        )
        .unwrap();

        let layer = ConfigLayer::from_file(&config_path).unwrap();
        assert_eq!(layer.no_inherit, true);
        assert_eq!(layer.line_width, Some(LineWidth::new(100).unwrap()));
    }

    #[test]
    fn test_config_layer_from_file_not_found() {
        let result = ConfigLayer::from_file(Path::new("/nonexistent/.hongdown.toml"));
        assert!(result.is_err());
    }

    #[test]
    fn test_config_layer_merge_simple_fields() {
        let base = Config {
            line_width: LineWidth::new(80).unwrap(),
            git_aware: true,
            ..Config::default()
        };

        let layer = ConfigLayer {
            line_width: Some(LineWidth::new(100).unwrap()),
            git_aware: Some(false),
            ..ConfigLayer::default()
        };

        let merged = layer.merge_over(base);
        assert_eq!(merged.line_width.get(), 100);
        assert_eq!(merged.git_aware, false);
    }

    #[test]
    fn test_config_layer_merge_preserves_unset() {
        let base = Config {
            line_width: LineWidth::new(120).unwrap(),
            git_aware: false,
            include: vec!["*.md".to_string()],
            ..Config::default()
        };

        let layer = ConfigLayer {
            line_width: Some(LineWidth::new(100).unwrap()),
            // git_aware and include are None, should preserve base
            ..ConfigLayer::default()
        };

        let merged = layer.merge_over(base);
        assert_eq!(merged.line_width.get(), 100);
        assert_eq!(merged.git_aware, false); // Preserved
        assert_eq!(merged.include, vec!["*.md".to_string()]); // Preserved
    }

    #[test]
    fn test_config_layer_merge_nested_structs() {
        let base = Config {
            heading: HeadingConfig {
                setext_h1: true,
                setext_h2: true,
                sentence_case: false,
                proper_nouns: vec!["Rust".to_string()],
                common_nouns: Vec::new(),
            },
            ..Config::default()
        };

        let layer = ConfigLayer {
            heading: Some(HeadingConfig {
                setext_h1: false,
                setext_h2: false,
                sentence_case: true,
                proper_nouns: vec!["Python".to_string()],
                common_nouns: Vec::new(),
            }),
            ..ConfigLayer::default()
        };

        let merged = layer.merge_over(base);
        assert_eq!(merged.heading.setext_h1, false);
        assert_eq!(merged.heading.setext_h2, false);
        assert_eq!(merged.heading.sentence_case, true);
        assert_eq!(merged.heading.proper_nouns, vec!["Python".to_string()]);
    }

    #[test]
    fn test_config_layer_merge_vec_replacement() {
        let base = Config {
            include: vec!["*.md".to_string(), "*.txt".to_string()],
            exclude: vec!["test/**".to_string()],
            ..Config::default()
        };

        let layer = ConfigLayer {
            include: Some(vec!["docs/*.md".to_string()]),
            // exclude is None, should preserve base
            ..ConfigLayer::default()
        };

        let merged = layer.merge_over(base);
        assert_eq!(merged.include, vec!["docs/*.md".to_string()]);
        assert_eq!(merged.exclude, vec!["test/**".to_string()]); // Preserved
    }
}

#[cfg(test)]
mod cascading_config_tests {
    use super::*;
    use tempfile::TempDir;

    #[test]
    fn test_try_load_layer_file_exists() {
        let temp_dir = TempDir::new().unwrap();
        let config_path = temp_dir.path().join(".hongdown.toml");
        std::fs::write(
            &config_path,
            r#"
line_width = 100
"#,
        )
        .unwrap();

        let layer = Config::try_load_layer(&config_path).unwrap();
        assert!(layer.is_some());
        assert_eq!(
            layer.unwrap().line_width,
            Some(LineWidth::new(100).unwrap())
        );
    }

    #[test]
    fn test_try_load_layer_file_not_exists() {
        let result = Config::try_load_layer(Path::new("/nonexistent/.hongdown.toml")).unwrap();
        assert!(result.is_none());
    }

    #[test]
    fn test_discover_project_config() {
        let temp_dir = TempDir::new().unwrap();
        let parent = temp_dir.path();
        let child = parent.join("project");
        std::fs::create_dir(&child).unwrap();

        let config_path = parent.join(".hongdown.toml");
        std::fs::write(&config_path, "line_width = 100").unwrap();

        let result = Config::discover_project_config(&child).unwrap();
        assert!(result.is_some());
        let (path, layer) = result.unwrap();
        assert_eq!(path, config_path);
        assert_eq!(layer.line_width, Some(LineWidth::new(100).unwrap()));
    }

    #[test]
    fn test_discover_project_config_not_found() {
        let temp_dir = TempDir::new().unwrap();
        let result = Config::discover_project_config(temp_dir.path()).unwrap();
        assert!(result.is_none());
    }

    #[test]
    fn test_load_cascading_project_only() {
        let temp_dir = TempDir::new().unwrap();
        let config_path = temp_dir.path().join(".hongdown.toml");
        std::fs::write(&config_path, "line_width = 100").unwrap();

        let (config, path) = Config::load_cascading(temp_dir.path()).unwrap();
        assert_eq!(path, Some(config_path));
        assert_eq!(config.line_width.get(), 100);
    }

    #[test]
    fn test_load_cascading_no_config() {
        let temp_dir = TempDir::new().unwrap();
        let (config, path) = Config::load_cascading(temp_dir.path()).unwrap();
        assert_eq!(path, None);
        assert_eq!(config, Config::default());
    }

    #[test]
    fn test_load_cascading_with_no_inherit() {
        let temp_dir = TempDir::new().unwrap();
        let config_path = temp_dir.path().join(".hongdown.toml");

        // Config with no_inherit = true, line_width = 100
        std::fs::write(
            &config_path,
            r#"
no_inherit = true
line_width = 100
"#,
        )
        .unwrap();

        let (config, _) = Config::load_cascading(temp_dir.path()).unwrap();

        // Should use config's values, ignoring any system/user configs
        assert_eq!(config.line_width.get(), 100);
        assert_eq!(config.no_inherit, true);
    }

    #[test]
    fn test_load_cascading_nearest_project_config() {
        let temp_dir = TempDir::new().unwrap();
        let parent = temp_dir.path();
        let child = parent.join("project");
        std::fs::create_dir(&child).unwrap();

        // Parent config: line_width = 120
        std::fs::write(parent.join(".hongdown.toml"), "line_width = 120").unwrap();

        // Child config: line_width = 100
        std::fs::write(child.join(".hongdown.toml"), "line_width = 100").unwrap();

        let (config, path) = Config::load_cascading(&child).unwrap();

        // Should use nearest (child) config, parent config is ignored
        assert_eq!(config.line_width.get(), 100);
        assert_eq!(path, Some(child.join(".hongdown.toml")));
    }

    #[test]
    fn test_load_cascading_searches_parent_dirs() {
        let temp_dir = TempDir::new().unwrap();
        let parent = temp_dir.path();
        let child = parent.join("project");
        std::fs::create_dir(&child).unwrap();

        // Only parent has config
        std::fs::write(
            parent.join(".hongdown.toml"),
            r#"
line_width = 120
git_aware = false
"#,
        )
        .unwrap();

        let (config, path) = Config::load_cascading(&child).unwrap();

        // Should find parent's config when searching from child
        assert_eq!(config.line_width.get(), 120);
        assert_eq!(config.git_aware, false);
        assert_eq!(path, Some(parent.join(".hongdown.toml")));
    }
}