saneyaml 0.1.1

use crate::{
    Error, ErrorCategory, Node, NodeValue as Value, Number, Result, Span,
    schema::DEFAULT_MAX_NESTING_DEPTH,
};
use std::collections::HashMap;

#[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
pub(crate) enum DuplicateKey {
    Null,
    Bool(bool),
    Integer(i128),
    Unsigned(u128),
    Float(u64),
    String(String),
    Sequence(Vec<DuplicateKey>),
    Mapping(Vec<(DuplicateKey, DuplicateKey)>),
}

impl DuplicateKey {
    fn label(&self) -> String {
        match self {
            DuplicateKey::Null => "null".to_string(),
            DuplicateKey::Bool(value) => value.to_string(),
            DuplicateKey::Integer(value) => value.to_string(),
            DuplicateKey::Unsigned(value) => value.to_string(),
            DuplicateKey::Float(bits) => f64::from_bits(*bits).to_string(),
            DuplicateKey::String(value) => value.clone(),
            DuplicateKey::Sequence(items) => {
                let items = items
                    .iter()
                    .map(DuplicateKey::label)
                    .collect::<Vec<_>>()
                    .join(", ");
                format!("[{items}]")
            }
            DuplicateKey::Mapping(entries) => {
                let entries = entries
                    .iter()
                    .map(|(key, value)| format!("{}: {}", key.label(), value.label()))
                    .collect::<Vec<_>>()
                    .join(", ");
                format!("{{{entries}}}")
            }
        }
    }
}

pub(crate) fn same_key_identity(left: &Node, right: &Node) -> Result<bool> {
    Ok(duplicate_key_identity_at(left, 1)? == duplicate_key_identity_at(right, 1)?)
}

pub(crate) fn check_duplicate_at_depth(
    seen: &mut HashMap<DuplicateKey, Span>,
    key: &Node,
    depth: usize,
) -> Result<()> {
    check_duplicate_at_depth_limit(seen, key, depth, Some(DEFAULT_MAX_NESTING_DEPTH))
}

pub(crate) fn check_duplicate_at_depth_limit(
    seen: &mut HashMap<DuplicateKey, Span>,
    key: &Node,
    depth: usize,
    max_depth: Option<usize>,
) -> Result<()> {
    let Some(key_identity) = duplicate_key_identity_with_limit(key, depth, max_depth)? else {
        return Ok(());
    };
    if let Some(previous) = seen.insert(key_identity.clone(), key.span) {
        let key_text = key_identity.label();
        return Err(Error::with_related_category(
            format!("duplicate mapping key `{key_text}`"),
            key.span,
            "previous key is here",
            previous,
            ErrorCategory::DuplicateKey,
        ));
    }
    Ok(())
}

fn duplicate_key_identity_at(key: &Node, depth: usize) -> Result<Option<DuplicateKey>> {
    duplicate_key_identity_with_limit(key, depth, Some(DEFAULT_MAX_NESTING_DEPTH))
}

fn duplicate_key_identity_with_limit(
    key: &Node,
    depth: usize,
    max_depth: Option<usize>,
) -> Result<Option<DuplicateKey>> {
    if max_depth.is_some_and(|max| depth > max) {
        return Err(Error::limit(
            "maximum YAML nesting depth exceeded",
            key.span,
        ));
    }

    Ok(match &key.value {
        Value::Null => Some(DuplicateKey::Null),
        Value::Bool(value) => Some(DuplicateKey::Bool(*value)),
        Value::Number(Number::Integer(value)) if *value < 0 => Some(DuplicateKey::Integer(*value)),
        Value::Number(Number::Integer(value)) => Some(DuplicateKey::Unsigned(*value as u128)),
        Value::Number(Number::Unsigned(value)) => Some(DuplicateKey::Unsigned(*value)),
        Value::Number(Number::Float(value)) => Some(DuplicateKey::Float(float_key_bits(*value))),
        Value::String(value) => Some(DuplicateKey::String(value.clone())),
        Value::Sequence(items) => duplicate_sequence_identity(items, next_depth(depth), max_depth)?,
        Value::Mapping(entries) => {
            duplicate_mapping_identity(entries, next_depth(depth), max_depth)?
        }
        Value::Tagged(tagged) => {
            duplicate_key_identity_with_limit(&tagged.value, next_depth(depth), max_depth)?
        }
    })
}

fn duplicate_sequence_identity(
    items: &[Node],
    depth: usize,
    max_depth: Option<usize>,
) -> Result<Option<DuplicateKey>> {
    let mut identities = Vec::with_capacity(items.len());
    for item in items {
        let Some(identity) = duplicate_key_identity_with_limit(item, depth, max_depth)? else {
            return Ok(None);
        };
        identities.push(identity);
    }
    Ok(Some(DuplicateKey::Sequence(identities)))
}

fn duplicate_mapping_identity(
    entries: &[(Node, Node)],
    depth: usize,
    max_depth: Option<usize>,
) -> Result<Option<DuplicateKey>> {
    let mut identities = Vec::with_capacity(entries.len());
    for (key, value) in entries {
        let Some(key_identity) = duplicate_key_identity_with_limit(key, depth, max_depth)? else {
            return Ok(None);
        };
        let Some(value_identity) = duplicate_key_identity_with_limit(value, depth, max_depth)?
        else {
            return Ok(None);
        };
        identities.push((key_identity, value_identity));
    }
    identities.sort();
    Ok(Some(DuplicateKey::Mapping(identities)))
}

fn next_depth(depth: usize) -> usize {
    depth.saturating_add(1)
}

fn float_key_bits(value: f64) -> u64 {
    if value == 0.0 {
        return 0.0f64.to_bits();
    }
    if value.is_nan() {
        return f64::NAN.to_bits();
    }
    value.to_bits()
}