bones_core/model/

item_id.rs

//! Validated identifier type for work items.
//!
//! All work items in bones carry a `bn-XXXX` identifier generated by the
//! [`terseid`] library.  `ItemId` is a validated newtype that wraps the
//! raw string and delegates to `terseid` for generation, parsing, and
//! resolution.

use serde::{Deserialize, Serialize};
use std::{fmt, str::FromStr};
use terseid::{
    IdConfig, IdGenerator, IdResolver, ParsedId, ResolverConfig, child_id as terseid_child_id,
    id_depth as terseid_id_depth, is_child_id as terseid_is_child_id, parse_id,
};

/// The prefix used for all bones work-item identifiers.
pub const BONES_PREFIX: &str = "bn";

// ---------------------------------------------------------------------------
// Core type
// ---------------------------------------------------------------------------

/// A validated work-item identifier (e.g. `bn-a7x`, `bn-a7x.1`).
///
/// The inner string is guaranteed to be a valid terseid ID with the `bn` prefix.
/// Construction goes through [`FromStr`], [`ItemId::new_unchecked`], or the
/// generator helpers.
#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Serialize, Deserialize)]
#[serde(try_from = "String", into = "String")]
pub struct ItemId(String);

// ---------------------------------------------------------------------------
// Error type
// ---------------------------------------------------------------------------

/// Errors that arise when constructing or resolving an [`ItemId`].
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ItemIdError {
    /// The raw string does not match the `<prefix>-<hash>[.<child>…]` pattern.
    InvalidFormat(String),
    /// The ID has a valid format but the wrong prefix.
    WrongPrefix { expected: String, found: String },
    /// Partial input matched more than one existing ID.
    Ambiguous {
        partial: String,
        matches: Vec<String>,
    },
    /// Partial input matched zero existing IDs.
    NotFound(String),
}

impl fmt::Display for ItemIdError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::InvalidFormat(raw) => write!(f, "invalid item ID format: '{raw}'"),
            Self::WrongPrefix { expected, found } => {
                write!(f, "expected prefix '{expected}', found '{found}'")
            }
            Self::Ambiguous { partial, matches } => {
                write!(f, "ambiguous ID '{partial}': matches {matches:?}")
            }
            Self::NotFound(id) => write!(f, "item ID not found: '{id}'"),
        }
    }
}

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

// ---------------------------------------------------------------------------
// Construction & validation
// ---------------------------------------------------------------------------

impl ItemId {
    /// Create an `ItemId` without validation.
    ///
    /// # Safety (logical)
    ///
    /// The caller **must** ensure `raw` is a valid terseid ID with the correct
    /// prefix.  Prefer [`FromStr`] or the generator helpers in production code.
    #[must_use]
    pub fn new_unchecked(raw: impl Into<String>) -> Self {
        Self(raw.into())
    }

    /// Parse and validate a raw string into an `ItemId`.
    ///
    /// The string is lower-cased and trimmed before validation.
    ///
    /// # Errors
    ///
    /// Returns [`ItemIdError::InvalidFormat`] if the format is wrong, or
    /// [`ItemIdError::WrongPrefix`] if the prefix is not `bn`.
    pub fn parse(raw: &str) -> Result<Self, ItemIdError> {
        let normalized = raw.trim().to_lowercase();

        // Validate via terseid
        let parsed =
            parse_id(&normalized).map_err(|_| ItemIdError::InvalidFormat(raw.to_string()))?;

        if parsed.prefix != BONES_PREFIX {
            return Err(ItemIdError::WrongPrefix {
                expected: BONES_PREFIX.to_string(),
                found: parsed.prefix,
            });
        }

        Ok(Self(parsed.to_id_string()))
    }

    /// Parse any valid terseid ID regardless of prefix.
    ///
    /// Used by the event parser and migration paths where IDs from external
    /// systems (e.g. beads with custom prefixes) must be accepted.
    ///
    /// # Errors
    ///
    /// Returns [`ItemIdError::InvalidFormat`] if the string is not a valid
    /// terseid ID.
    pub fn parse_any_prefix(raw: &str) -> Result<Self, ItemIdError> {
        let normalized = raw.trim().to_lowercase();
        let parsed =
            parse_id(&normalized).map_err(|_| ItemIdError::InvalidFormat(raw.to_string()))?;
        Ok(Self(parsed.to_id_string()))
    }

    /// Return the raw ID string.
    #[must_use]
    pub fn as_str(&self) -> &str {
        &self.0
    }

    /// Parse the inner string into a terseid [`ParsedId`].
    ///
    /// This never fails because `ItemId` guarantees validity at construction.
    ///
    /// # Panics
    ///
    /// Panics if the internal invariant is broken (the stored string is not a
    /// valid terseid ID).  This should never happen through the public API.
    #[must_use]
    pub fn parsed(&self) -> ParsedId {
        parse_id(&self.0).expect("ItemId invariant broken")
    }

    /// Return `true` if this is a root ID (no child path segments).
    #[must_use]
    pub fn is_root(&self) -> bool {
        !terseid_is_child_id(&self.0)
    }

    /// Return `true` if this is a child ID (has child path segments).
    #[must_use]
    pub fn is_child(&self) -> bool {
        terseid_is_child_id(&self.0)
    }

    /// Depth of the child path (0 for root IDs).
    #[must_use]
    pub fn depth(&self) -> usize {
        terseid_id_depth(&self.0)
    }

    /// Create a child ID by appending a child number.
    ///
    /// ```
    /// # use bones_core::model::item_id::ItemId;
    /// let parent = ItemId::parse("bn-a7x").unwrap();
    /// let child = parent.child(1);
    /// assert_eq!(child.as_str(), "bn-a7x.1");
    /// ```
    #[must_use]
    pub fn child(&self, number: u32) -> Self {
        Self(terseid_child_id(&self.0, number))
    }

    /// Return the parent `ItemId`, or `None` if this is a root.
    #[must_use]
    pub fn parent(&self) -> Option<Self> {
        self.parsed().parent().map(Self)
    }

    /// Return `true` if `self` is a descendant of `ancestor`.
    #[must_use]
    pub fn is_child_of(&self, ancestor: &Self) -> bool {
        self.parsed().is_child_of(ancestor.as_str())
    }
}

// ---------------------------------------------------------------------------
// Trait implementations
// ---------------------------------------------------------------------------

impl FromStr for ItemId {
    type Err = ItemIdError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        Self::parse(s)
    }
}

impl fmt::Display for ItemId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(&self.0)
    }
}

impl AsRef<str> for ItemId {
    fn as_ref(&self) -> &str {
        &self.0
    }
}

impl From<ItemId> for String {
    fn from(id: ItemId) -> Self {
        id.0
    }
}

impl TryFrom<String> for ItemId {
    type Error = ItemIdError;

    fn try_from(value: String) -> Result<Self, Self::Error> {
        Self::parse(&value)
    }
}

// ---------------------------------------------------------------------------
// Generator helper
// ---------------------------------------------------------------------------

/// Create a configured [`IdGenerator`] with the `bn` prefix and sensible
/// defaults for a bones repository.
#[must_use]
pub fn bones_id_generator() -> IdGenerator {
    IdGenerator::new(IdConfig::new(BONES_PREFIX))
}

/// Generate a new `ItemId` from a seed and current item count.
///
/// `seed` — typically `format!("{title}\0{nonce}")`.
/// `item_count` — current number of existing items (drives adaptive length).
/// `exists` — returns `true` if a candidate ID is already taken.
pub fn generate_item_id(seed: &str, item_count: usize, exists: impl Fn(&str) -> bool) -> ItemId {
    let generator = bones_id_generator();
    let id = generator.generate(
        |nonce| format!("{seed}\0{nonce}").into_bytes(),
        item_count,
        &exists,
    );
    ItemId(id)
}

// ---------------------------------------------------------------------------
// Resolver helper
// ---------------------------------------------------------------------------

/// Resolve partial CLI input into a full `ItemId`.
///
/// Resolution order (delegated to [`terseid::IdResolver`]):
/// 1. Exact match (case-insensitive)
/// 2. Prefix normalisation — bare hash `a7x` becomes `bn-a7x`
/// 3. Substring match on the hash portion
///
/// `exists` — returns `true` if a full ID exists.
/// `substring_match` — returns all full IDs whose hash contains the input.
///
/// # Errors
///
/// * [`ItemIdError::Ambiguous`] — substring matched more than one ID.
/// * [`ItemIdError::NotFound`] — no match at all.
pub fn resolve_item_id(
    input: &str,
    exists: impl Fn(&str) -> bool,
    substring_match: impl Fn(&str) -> Vec<String>,
) -> Result<ItemId, ItemIdError> {
    let cfg = ResolverConfig::new(BONES_PREFIX);
    let id_resolver = IdResolver::new(cfg);

    let result = id_resolver
        .resolve(input, &exists, &substring_match)
        .map_err(|e| match e {
            terseid::TerseIdError::AmbiguousId { partial, matches } => {
                ItemIdError::Ambiguous { partial, matches }
            }
            terseid::TerseIdError::NotFound { id } => ItemIdError::NotFound(id),
            other => ItemIdError::InvalidFormat(other.to_string()),
        })?;

    // The resolved ID came from the known-good set, so it is valid.
    Ok(ItemId(result.id))
}

// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------

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

    // === Construction & validation ==========================================

    #[test]
    fn parse_valid_root_id() {
        let id = ItemId::parse("bn-a7x").unwrap();
        assert_eq!(id.as_str(), "bn-a7x");
        assert!(id.is_root());
        assert!(!id.is_child());
        assert_eq!(id.depth(), 0);
    }

    #[test]
    fn parse_valid_child_id() {
        let id = ItemId::parse("bn-a7x.1").unwrap();
        assert_eq!(id.as_str(), "bn-a7x.1");
        assert!(!id.is_root());
        assert!(id.is_child());
        assert_eq!(id.depth(), 1);
    }

    #[test]
    fn parse_valid_grandchild_id() {
        let id = ItemId::parse("bn-a7x.1.3").unwrap();
        assert_eq!(id.depth(), 2);
    }

    #[test]
    fn parse_normalises_case() {
        let id = ItemId::parse("BN-A7X").unwrap();
        assert_eq!(id.as_str(), "bn-a7x");
    }

    #[test]
    fn parse_trims_whitespace() {
        let id = ItemId::parse("  bn-a7x  ").unwrap();
        assert_eq!(id.as_str(), "bn-a7x");
    }

    #[test]
    fn parse_rejects_wrong_prefix() {
        let err = ItemId::parse("tk-a7x").unwrap_err();
        assert!(matches!(err, ItemIdError::WrongPrefix { .. }));
    }

    #[test]
    fn parse_rejects_invalid_format() {
        assert!(ItemId::parse("notanid").is_err());
        assert!(ItemId::parse("bn-").is_err());
        assert!(ItemId::parse("").is_err());
        // 4-char hash without digit → invalid format per terseid rules
        assert!(ItemId::parse("bn-abcd").is_err());
    }

    #[test]
    fn parse_accepts_longer_hash_with_digit() {
        let id = ItemId::parse("bn-a7x3q9").unwrap();
        assert_eq!(id.as_str(), "bn-a7x3q9");
    }

    // === FromStr / Display round-trip =======================================

    #[test]
    fn display_fromstr_roundtrip() {
        let id: ItemId = "bn-a7x".parse().unwrap();
        let rendered = id.to_string();
        let reparsed: ItemId = rendered.parse().unwrap();
        assert_eq!(id, reparsed);
    }

    #[test]
    fn display_fromstr_roundtrip_child() {
        let id: ItemId = "bn-a7x.1.3".parse().unwrap();
        let rendered = id.to_string();
        let reparsed: ItemId = rendered.parse().unwrap();
        assert_eq!(id, reparsed);
    }

    // === Serde round-trip ===================================================

    #[test]
    fn serde_json_roundtrip() {
        let id = ItemId::parse("bn-a7x.1").unwrap();
        let json = serde_json::to_string(&id).unwrap();
        assert_eq!(json, "\"bn-a7x.1\"");
        let deser: ItemId = serde_json::from_str(&json).unwrap();
        assert_eq!(id, deser);
    }

    #[test]
    fn serde_rejects_invalid() {
        let result = serde_json::from_str::<ItemId>("\"notvalid\"");
        assert!(result.is_err());
    }

    // === Child / parent =====================================================

    #[test]
    fn child_creates_valid_id() {
        let parent = ItemId::parse("bn-a7x").unwrap();
        let child = parent.child(1);
        assert_eq!(child.as_str(), "bn-a7x.1");
        assert!(child.is_child());
    }

    #[test]
    fn grandchild_creation() {
        let root = ItemId::parse("bn-a7x").unwrap();
        let child = root.child(1);
        let grandchild = child.child(3);
        assert_eq!(grandchild.as_str(), "bn-a7x.1.3");
        assert_eq!(grandchild.depth(), 2);
    }

    #[test]
    fn parent_of_root_is_none() {
        let root = ItemId::parse("bn-a7x").unwrap();
        assert!(root.parent().is_none());
    }

    #[test]
    fn parent_of_child() {
        let child = ItemId::parse("bn-a7x.1").unwrap();
        let parent = child.parent().unwrap();
        assert_eq!(parent.as_str(), "bn-a7x");
    }

    #[test]
    fn parent_of_grandchild() {
        let gc = ItemId::parse("bn-a7x.1.3").unwrap();
        let parent = gc.parent().unwrap();
        assert_eq!(parent.as_str(), "bn-a7x.1");
    }

    #[test]
    fn is_child_of_works() {
        let root = ItemId::parse("bn-a7x").unwrap();
        let child = ItemId::parse("bn-a7x.1").unwrap();
        let gc = ItemId::parse("bn-a7x.1.3").unwrap();

        assert!(child.is_child_of(&root));
        assert!(gc.is_child_of(&root));
        assert!(gc.is_child_of(&child));
        assert!(!root.is_child_of(&child));
        assert!(!child.is_child_of(&gc));
    }

    // === Generation =========================================================

    #[test]
    fn generate_produces_valid_id() {
        let id = generate_item_id("my test item", 0, |_| false);
        assert!(id.as_str().starts_with("bn-"));
        assert!(id.is_root());
        // Should parse back successfully
        let reparsed = ItemId::parse(id.as_str()).unwrap();
        assert_eq!(id, reparsed);
    }

    #[test]
    fn generate_deterministic_with_same_seed() {
        let id1 = generate_item_id("seed-abc", 0, |_| false);
        let id2 = generate_item_id("seed-abc", 0, |_| false);
        assert_eq!(id1, id2);
    }

    #[test]
    fn generate_different_seeds_different_ids() {
        let id1 = generate_item_id("seed-one", 0, |_| false);
        let id2 = generate_item_id("seed-two", 0, |_| false);
        assert_ne!(id1, id2);
    }

    #[test]
    fn generate_avoids_collisions() {
        let mut taken: HashSet<String> = HashSet::new();

        for i in 0..20 {
            let id = generate_item_id(&format!("item-{i}"), taken.len(), |candidate| {
                taken.contains(candidate)
            });
            assert!(
                taken.insert(id.as_str().to_string()),
                "collision on iteration {i}: {}",
                id
            );
        }

        assert_eq!(taken.len(), 20);
    }

    #[test]
    fn generate_adaptive_length_grows() {
        // With 0 items, should use short hash (min_hash_length = 3)
        let generator = bones_id_generator();
        let short = generator.optimal_length(0);
        assert_eq!(short, 3);

        // With many items, should use longer hash
        let long = generator.optimal_length(100_000);
        assert!(long > short, "expected adaptive growth: {long} > {short}");
    }

    // === Resolution =========================================================

    #[test]
    fn resolve_exact() {
        let known = vec!["bn-a7x".to_string(), "bn-b8y".to_string()];
        let id = resolve_item_id(
            "bn-a7x",
            |candidate| known.contains(&candidate.to_string()),
            |_sub| vec![],
        )
        .unwrap();
        assert_eq!(id.as_str(), "bn-a7x");
    }

    #[test]
    fn resolve_bare_hash() {
        let known = vec!["bn-a7x".to_string()];
        let id = resolve_item_id(
            "a7x",
            |candidate| known.contains(&candidate.to_string()),
            |_sub| vec![],
        )
        .unwrap();
        assert_eq!(id.as_str(), "bn-a7x");
    }

    #[test]
    fn resolve_substring() {
        let known = vec!["bn-a7x".to_string(), "bn-b8y".to_string()];
        let id = resolve_item_id(
            "a7",
            |candidate| known.contains(&candidate.to_string()),
            |sub| {
                known
                    .iter()
                    .filter(|id| id.split('-').last().is_some_and(|hash| hash.contains(sub)))
                    .cloned()
                    .collect()
            },
        )
        .unwrap();
        assert_eq!(id.as_str(), "bn-a7x");
    }

    #[test]
    fn resolve_ambiguous() {
        let known = vec!["bn-a7x".to_string(), "bn-a7y".to_string()];
        let err = resolve_item_id(
            "a7",
            |candidate| known.contains(&candidate.to_string()),
            |sub| {
                known
                    .iter()
                    .filter(|id| id.split('-').last().is_some_and(|hash| hash.contains(sub)))
                    .cloned()
                    .collect()
            },
        )
        .unwrap_err();
        assert!(matches!(err, ItemIdError::Ambiguous { .. }));
    }

    #[test]
    fn resolve_not_found() {
        let err = resolve_item_id("zzz", |_| false, |_| vec![]).unwrap_err();
        assert!(matches!(err, ItemIdError::NotFound(_)));
    }

    // === Ordering & Hash ====================================================

    #[test]
    fn ordering_is_lexicographic() {
        let a = ItemId::parse("bn-a7x").unwrap();
        let b = ItemId::parse("bn-b8y").unwrap();
        assert!(a < b);
    }

    #[test]
    fn hash_set_deduplication() {
        let id1 = ItemId::parse("bn-a7x").unwrap();
        let id2 = ItemId::parse("bn-a7x").unwrap();
        let mut set = HashSet::new();
        set.insert(id1);
        set.insert(id2);
        assert_eq!(set.len(), 1);
    }

    // === AsRef / Into =======================================================

    #[test]
    fn as_ref_str() {
        let id = ItemId::parse("bn-a7x").unwrap();
        let s: &str = id.as_ref();
        assert_eq!(s, "bn-a7x");
    }

    #[test]
    fn into_string() {
        let id = ItemId::parse("bn-a7x").unwrap();
        let s: String = id.into();
        assert_eq!(s, "bn-a7x");
    }

    // === new_unchecked ======================================================

    #[test]
    fn new_unchecked_trusts_caller() {
        let id = ItemId::new_unchecked("bn-a7x");
        assert_eq!(id.as_str(), "bn-a7x");
    }

    // === Error display ======================================================

    #[test]
    fn error_display() {
        let e = ItemIdError::InvalidFormat("bad".into());
        assert!(e.to_string().contains("bad"));

        let e = ItemIdError::WrongPrefix {
            expected: "bn".into(),
            found: "tk".into(),
        };
        assert!(e.to_string().contains("bn"));
        assert!(e.to_string().contains("tk"));

        let e = ItemIdError::Ambiguous {
            partial: "a7".into(),
            matches: vec!["bn-a7x".into(), "bn-a7y".into()],
        };
        assert!(e.to_string().contains("a7"));

        let e = ItemIdError::NotFound("zzz".into());
        assert!(e.to_string().contains("zzz"));
    }
}