unified-agent-api-codex 0.3.5

use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::env;
use std::ffi::OsString;
use std::fs as std_fs;
use std::path::{Path, PathBuf};
use std::sync::{Mutex, OnceLock};
use std::time::SystemTime;

#[cfg(unix)]
use std::os::unix::fs::PermissionsExt;

use super::{
    CapabilityFeatureOverrides, CapabilityOverrides, CapabilityProbeStep, CodexCapabilities,
    CodexFeatureFlags,
};

/// Cache interaction policy for capability probes.
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
pub enum CapabilityCachePolicy {
    /// Use cached entries when fingerprints match; fall back to probing when
    /// fingerprints differ or are missing and write fresh snapshots back.
    #[default]
    PreferCache,
    /// Always run probes, overwriting any existing cache entry for the binary (useful for TTL/backoff windows or hot-swaps that keep the same path).
    Refresh,
    /// Skip cache reads and writes to force an isolated snapshot.
    Bypass,
}

/// Cache key for capability snapshots derived from a specific Codex binary path.
///
/// Cache lookups should canonicalize the path when possible so symlinked binaries
/// collapse to a single entry.
#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize, Deserialize)]
pub struct CapabilityCacheKey {
    /// Canonical binary path when resolvable; otherwise the original path.
    pub binary_path: PathBuf,
}

/// File metadata used to invalidate cached capability snapshots when the binary changes.
#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
pub struct BinaryFingerprint {
    /// Canonical path if the binary resolves through symlinks.
    pub canonical_path: Option<PathBuf>,
    /// Last modification time of the binary on disk (`metadata().modified()`).
    pub modified: Option<SystemTime>,
    /// File length from `metadata().len()`, useful for cheap change detection.
    pub len: Option<u64>,
}

const PATH_ENV: &str = "PATH";

pub(crate) fn capability_cache() -> &'static Mutex<HashMap<CapabilityCacheKey, CodexCapabilities>> {
    static CACHE: OnceLock<Mutex<HashMap<CapabilityCacheKey, CodexCapabilities>>> = OnceLock::new();
    CACHE.get_or_init(|| Mutex::new(HashMap::new()))
}

pub(crate) fn effective_path_env(env_overrides: &[(String, String)]) -> Option<OsString> {
    env_overrides
        .iter()
        .rev()
        .find_map(|(key, value)| path_env_key_matches(key).then(|| OsString::from(value)))
        .or_else(|| env::var_os(PATH_ENV))
}

#[cfg(windows)]
fn path_env_key_matches(key: &str) -> bool {
    key.eq_ignore_ascii_case(PATH_ENV)
}

#[cfg(not(windows))]
fn path_env_key_matches(key: &str) -> bool {
    key == PATH_ENV
}

pub(crate) fn resolve_binary_path(
    binary: &Path,
    current_dir: Option<&Path>,
    path_env: Option<OsString>,
) -> PathBuf {
    if is_path_qualified(binary) {
        return resolve_path_qualified_binary(binary.to_path_buf(), current_dir);
    }

    find_binary_on_path(binary, path_env, current_dir).unwrap_or_else(|| binary.to_path_buf())
}

pub(crate) fn capability_cache_key(binary: &Path) -> CapabilityCacheKey {
    capability_cache_key_for_current_dir(binary, None)
}

pub(crate) fn capability_cache_key_for_current_dir(
    binary: &Path,
    current_dir: Option<&Path>,
) -> CapabilityCacheKey {
    capability_cache_key_for_current_dir_with_env(binary, current_dir, &[])
}

pub(crate) fn capability_cache_key_for_current_dir_with_env(
    binary: &Path,
    current_dir: Option<&Path>,
    env_overrides: &[(String, String)],
) -> CapabilityCacheKey {
    let resolved = resolve_binary_path(binary, current_dir, effective_path_env(env_overrides));
    let canonical = std_fs::canonicalize(&resolved).unwrap_or(resolved);
    CapabilityCacheKey {
        binary_path: canonical,
    }
}

fn is_path_qualified(path: &Path) -> bool {
    path.is_absolute()
        || path
            .parent()
            .is_some_and(|parent| !parent.as_os_str().is_empty())
}

fn resolve_path_qualified_binary(binary_path: PathBuf, current_dir: Option<&Path>) -> PathBuf {
    if binary_path.is_absolute() {
        return binary_path;
    }

    let joined = effective_base_dir(current_dir)
        .map(|cwd| cwd.join(&binary_path))
        .unwrap_or(binary_path);

    std_fs::canonicalize(&joined).unwrap_or(joined)
}

fn effective_base_dir(base_dir: Option<&Path>) -> Option<PathBuf> {
    match base_dir {
        Some(path) if path.is_absolute() => Some(path.to_path_buf()),
        Some(path) => env::current_dir().ok().map(|cwd| cwd.join(path)),
        None => env::current_dir().ok(),
    }
}

fn find_binary_on_path(
    binary_name: &Path,
    path_env: Option<OsString>,
    current_dir: Option<&Path>,
) -> Option<PathBuf> {
    let path_env = path_env?;
    let effective_cwd = effective_base_dir(current_dir);
    env::split_paths(&path_env)
        .find_map(|directory| {
            let search_dir = if directory.is_absolute() {
                directory
            } else if let Some(cwd) = effective_cwd.as_deref() {
                cwd.join(directory)
            } else {
                directory
            };
            candidate_binary_path(&search_dir, binary_name)
        })
        .map(|candidate| std_fs::canonicalize(&candidate).unwrap_or(candidate))
}

fn candidate_binary_path(directory: &Path, binary_name: &Path) -> Option<PathBuf> {
    let candidate = directory.join(binary_name);
    if is_runnable_path_candidate(&candidate) {
        return Some(candidate);
    }

    #[cfg(windows)]
    {
        if candidate.extension().is_some() {
            return None;
        }

        let pathext =
            env::var_os("PATHEXT").unwrap_or_else(|| OsString::from(".COM;.EXE;.BAT;.CMD"));
        for extension in pathext.to_string_lossy().split(';') {
            let extension = extension.trim();
            if extension.is_empty() {
                continue;
            }

            let suffixed = candidate.with_extension(extension.trim_start_matches('.'));
            if is_runnable_path_candidate(&suffixed) {
                return Some(suffixed);
            }
        }
    }

    None
}

fn is_runnable_path_candidate(candidate: &Path) -> bool {
    let Ok(metadata) = std_fs::metadata(candidate) else {
        return false;
    };

    if !metadata.is_file() {
        return false;
    }

    #[cfg(unix)]
    {
        metadata.permissions().mode() & 0o111 != 0
    }

    #[cfg(not(unix))]
    {
        true
    }
}

pub(crate) fn has_fingerprint_metadata(fingerprint: &Option<BinaryFingerprint>) -> bool {
    fingerprint.is_some()
}

pub(crate) fn cached_capabilities(
    key: &CapabilityCacheKey,
    fingerprint: &Option<BinaryFingerprint>,
) -> Option<CodexCapabilities> {
    let cache = capability_cache().lock().ok()?;
    let cached = cache.get(key)?;
    if !has_fingerprint_metadata(&cached.fingerprint) || !has_fingerprint_metadata(fingerprint) {
        return None;
    }
    if fingerprints_match(&cached.fingerprint, fingerprint) {
        Some(cached.clone())
    } else {
        None
    }
}

pub(crate) fn update_capability_cache(capabilities: CodexCapabilities) {
    if !has_fingerprint_metadata(&capabilities.fingerprint) {
        return;
    }
    if let Ok(mut cache) = capability_cache().lock() {
        cache.insert(capabilities.cache_key.clone(), capabilities);
    }
}

/// Returns all capability cache entries keyed by canonical binary path.
pub fn capability_cache_entries() -> Vec<CodexCapabilities> {
    capability_cache()
        .lock()
        .map(|cache| cache.values().cloned().collect())
        .unwrap_or_default()
}

/// Returns the cached capabilities for a specific binary path if present.
pub fn capability_cache_entry(binary: &Path) -> Option<CodexCapabilities> {
    let key = capability_cache_key(binary);
    capability_cache()
        .lock()
        .ok()
        .and_then(|cache| cache.get(&key).cloned())
}

/// Removes the cached capabilities for a specific binary. Returns true when an entry was removed.
pub fn clear_capability_cache_entry(binary: &Path) -> bool {
    let key = capability_cache_key(binary);
    capability_cache()
        .lock()
        .ok()
        .map(|mut cache| cache.remove(&key).is_some())
        .unwrap_or(false)
}

/// Clears all cached capability snapshots.
pub fn clear_capability_cache() {
    if let Ok(mut cache) = capability_cache().lock() {
        cache.clear();
    }
}

pub(crate) fn current_fingerprint(key: &CapabilityCacheKey) -> Option<BinaryFingerprint> {
    let canonical = std_fs::canonicalize(&key.binary_path).ok();
    let metadata_path = canonical.as_deref().unwrap_or(key.binary_path.as_path());
    let metadata = std_fs::metadata(metadata_path).ok()?;
    Some(BinaryFingerprint {
        canonical_path: canonical,
        modified: metadata.modified().ok(),
        len: Some(metadata.len()),
    })
}

pub(crate) fn fingerprints_match(
    cached: &Option<BinaryFingerprint>,
    fresh: &Option<BinaryFingerprint>,
) -> bool {
    cached == fresh
}

pub(crate) fn finalize_capabilities_with_overrides(
    mut capabilities: CodexCapabilities,
    overrides: &CapabilityOverrides,
    cache_key: CapabilityCacheKey,
    fingerprint: Option<BinaryFingerprint>,
    manual_source: bool,
) -> CodexCapabilities {
    capabilities.cache_key = cache_key;
    capabilities.fingerprint = fingerprint;

    let mut applied = manual_source;

    if let Some(version) = overrides.version.clone() {
        capabilities.version = Some(version);
        applied = true;
    }

    if apply_feature_overrides(&mut capabilities.features, &overrides.features) {
        applied = true;
    }

    if applied
        && !capabilities
            .probe_plan
            .steps
            .contains(&CapabilityProbeStep::ManualOverride)
    {
        capabilities
            .probe_plan
            .steps
            .push(CapabilityProbeStep::ManualOverride);
    }

    capabilities
}

fn apply_feature_overrides(
    features: &mut CodexFeatureFlags,
    overrides: &CapabilityFeatureOverrides,
) -> bool {
    let mut applied = false;

    if let Some(value) = overrides.supports_features_list {
        features.supports_features_list = value;
        applied = true;
    }

    if let Some(value) = overrides.supports_output_schema {
        features.supports_output_schema = value;
        applied = true;
    }

    if let Some(value) = overrides.supports_add_dir {
        features.supports_add_dir = value;
        applied = true;
    }

    if let Some(value) = overrides.supports_mcp_login {
        features.supports_mcp_login = value;
        applied = true;
    }

    applied
}