ryo-symbol 0.1.0

//! File path resolver for converting symbol paths to file paths
//!
//! Centralizes the logic for resolving SymbolPath to WorkspaceFilePath.
//! This is the reverse of SymbolPathResolver.

use std::path::PathBuf;

use crate::crate_name::CrateName;
use crate::error::ResolutionError;
use crate::file_path::WorkspaceFilePath;
use crate::metadata::{CrateInfo, TargetKind};
use crate::path::SymbolPath;
use crate::registry::SymbolRegistry;
use crate::resolver::WorkspacePathResolver;

/// Resolves symbol paths to file paths
///
/// # Design
///
/// This resolver centralizes the conversion from Rust symbol paths to
/// file system paths (WorkspaceFilePath). It provides two resolution strategies:
///
/// 1. **Registry-based** (preferred): Uses SymbolRegistry span info
/// 2. **Inference-based** (fallback): Infers file path from module structure
///
/// # Example
///
/// ```ignore
/// let resolver = FilePathResolver::new(workspace_root);
///
/// // With registry (preferred - uses span info)
/// let path = resolver.resolve_with_registry(&symbol_path, &registry)?;
///
/// // Without registry (inference-based)
/// let path = resolver.resolve_by_inference(&symbol_path)?;
/// ```
#[derive(Debug, Clone)]
pub struct FilePathResolver {
    workspace_resolver: WorkspacePathResolver,
}

impl FilePathResolver {
    /// Create a new resolver with the given workspace root
    pub fn new(workspace_root: PathBuf) -> Self {
        Self {
            workspace_resolver: WorkspacePathResolver::new(workspace_root),
        }
    }

    /// Create from an existing WorkspacePathResolver
    pub fn from_workspace_resolver(workspace_resolver: WorkspacePathResolver) -> Self {
        Self { workspace_resolver }
    }

    /// Get the workspace root
    pub fn workspace_root(&self) -> &std::path::Path {
        self.workspace_resolver.workspace_root()
    }

    /// Resolve SymbolPath to WorkspaceFilePath using SymbolRegistry
    ///
    /// This is the preferred method as it uses span information from the registry.
    ///
    /// # Returns
    ///
    /// - `Ok(WorkspaceFilePath)` - The file containing the symbol
    /// - `Err(ResolutionError::SymbolNotFound)` - Symbol not in registry
    /// - `Err(ResolutionError::NoSpanInfo)` - Symbol found but has no span
    pub fn resolve_with_registry(
        &self,
        path: &SymbolPath,
        registry: &SymbolRegistry,
    ) -> Result<WorkspaceFilePath, ResolutionError> {
        let symbol_id = registry
            .lookup(path)
            .ok_or_else(|| ResolutionError::SymbolNotFound(path.to_string()))?;

        let span = registry
            .span(symbol_id)
            .ok_or_else(|| ResolutionError::NoSpanInfo(path.to_string()))?;

        Ok(span.file.clone())
    }

    /// Resolve SymbolPath to WorkspaceFilePath, falling back to inference
    ///
    /// Tries registry first, then falls back to inference if:
    /// - Symbol not found in registry
    /// - Symbol has no span info
    ///
    /// # Arguments
    ///
    /// - `path` - The symbol path to resolve
    /// - `registry` - Optional registry for span-based resolution
    pub fn resolve(
        &self,
        path: &SymbolPath,
        registry: Option<&SymbolRegistry>,
    ) -> Result<WorkspaceFilePath, ResolutionError> {
        // Try registry-based resolution first
        if let Some(reg) = registry {
            if let Ok(file_path) = self.resolve_with_registry(path, reg) {
                return Ok(file_path);
            }
        }

        // Fallback to inference
        self.resolve_by_inference(path)
    }

    /// Resolve SymbolPath to WorkspaceFilePath by inferring from module structure
    ///
    /// Follows Rust's module conventions:
    /// - `crate_name` → `src/lib.rs` or `src/main.rs`
    /// - `crate_name::foo` → `src/foo.rs` or `src/foo/mod.rs`
    /// - `crate_name::foo::bar` → `src/foo/bar.rs` or `src/foo/bar/mod.rs`
    /// - `crate_name::foo::bar::Item` → same as `crate_name::foo::bar`
    ///
    /// # Note
    ///
    /// This method cannot distinguish between:
    /// - A module file (`foo.rs` defines module `foo`)
    /// - An item in a parent module (`foo` is an item in `lib.rs`)
    ///
    /// Use `resolve_with_registry` when accuracy is critical.
    pub fn resolve_by_inference(
        &self,
        path: &SymbolPath,
    ) -> Result<WorkspaceFilePath, ResolutionError> {
        // Get crate name from symbol path (first segment)
        let crate_name = CrateName::new_unchecked(path.crate_name());

        // Skip crate name, get remaining segments
        let segments: Vec<&str> = path.segments().skip(1).collect();

        if segments.is_empty() {
            // Crate root → src/lib.rs
            return Ok(self
                .workspace_resolver
                .resolve_relative_with_crate("src/lib.rs", crate_name));
        }

        // Try progressively shorter paths (item might be in parent module)
        // e.g., crate::foo::bar::Baz → try foo/bar.rs, then foo.rs, then lib.rs
        for depth in (0..=segments.len()).rev() {
            let module_segments = &segments[..depth];

            if module_segments.is_empty() {
                // Check lib.rs
                return Ok(self
                    .workspace_resolver
                    .resolve_relative_with_crate("src/lib.rs", crate_name));
            }

            // Build file path: src/foo/bar.rs
            let mut path_buf = PathBuf::from("src");
            for seg in module_segments {
                path_buf.push(seg);
            }
            path_buf.set_extension("rs");

            let file_path = self
                .workspace_resolver
                .resolve_relative_with_crate(&path_buf, crate_name.clone());

            // We return the first candidate (deepest module path)
            // Caller should verify file exists if needed
            if depth == segments.len() || depth == segments.len() - 1 {
                return Ok(file_path);
            }
        }

        // Should not reach here, but return lib.rs as ultimate fallback
        Ok(self
            .workspace_resolver
            .resolve_relative_with_crate("src/lib.rs", crate_name))
    }

    /// Resolve with mod.rs fallback
    ///
    /// First tries `src/foo/bar.rs`, then `src/foo/bar/mod.rs`.
    /// Returns both candidates for caller to check existence.
    pub fn resolve_candidates(&self, path: &SymbolPath) -> Vec<WorkspaceFilePath> {
        // Get crate name from symbol path (first segment)
        let crate_name = CrateName::new_unchecked(path.crate_name());

        let segments: Vec<&str> = path.segments().skip(1).collect();

        if segments.is_empty() {
            return vec![
                self.workspace_resolver
                    .resolve_relative_with_crate("src/lib.rs", crate_name.clone()),
                self.workspace_resolver
                    .resolve_relative_with_crate("src/main.rs", crate_name),
            ];
        }

        // For module path, try both file.rs and dir/mod.rs patterns
        let mut candidates = Vec::with_capacity(2);

        // Build module path
        let mut path_buf = PathBuf::from("src");
        for seg in &segments {
            path_buf.push(seg);
        }

        // Candidate 1: src/foo/bar.rs
        let mut file_path = path_buf.clone();
        file_path.set_extension("rs");
        candidates.push(
            self.workspace_resolver
                .resolve_relative_with_crate(&file_path, crate_name.clone()),
        );

        // Candidate 2: src/foo/bar/mod.rs
        let mut mod_path = path_buf;
        mod_path.push("mod.rs");
        candidates.push(
            self.workspace_resolver
                .resolve_relative_with_crate(&mod_path, crate_name),
        );

        candidates
    }

    /// Resolve SymbolPath to WorkspaceFilePath candidates using Cargo metadata.
    ///
    /// This is the accurate, metadata-driven file resolution method that correctly handles:
    /// - Bin-only crates (no lib.rs, only main.rs)
    /// - Mixed crates (both lib.rs and main.rs)
    /// - Library-only crates
    /// - Workspace crates in subdirectories
    ///
    /// # Main Symbol Handling
    ///
    /// This method handles the `main::` prefix correctly by skipping both "main" and
    /// the crate name when processing segments:
    ///
    /// ```ignore
    /// // Library symbol:
    /// "my_crate::models::User"
    /// segments: skip(1) → ["models", "User"]
    ///
    /// // Binary symbol:
    /// "main::my_crate::models::User"
    /// segments: skip(2) → ["models", "User"]  // Skip both "main" and "my_crate"
    /// ```
    ///
    /// # Crate Root Resolution
    ///
    /// For crate root symbols (0 or 1 segments after crate name):
    ///
    /// ```ignore
    /// // Library crate:
    /// "my_crate" or "my_crate::Item" → ["src/lib.rs"]
    ///
    /// // Bin-only crate:
    /// "main::my_app" or "main::my_app::Item" → ["src/main.rs"]
    ///
    /// // Mixed crate (both lib and bin):
    /// "my_crate::Item" → ["src/lib.rs", "src/main.rs"]
    /// "main::my_crate::Item" → ["src/main.rs", "src/lib.rs"]
    /// ```
    ///
    /// The `resolve_crate_root_candidates()` method consults `crate_info.entry_points`
    /// to determine which files to include.
    ///
    /// # Sub-Module Resolution
    ///
    /// For nested modules (2+ segments after crate name):
    ///
    /// ```ignore
    /// "my_crate::models::User" → ["src/models.rs", "src/models/mod.rs"]
    /// "main::my_app::cli::Args" → ["src/cli.rs", "src/cli/mod.rs"]
    /// ```
    ///
    /// # Arguments
    ///
    /// * `path` - The symbol path to resolve (may have `main::` prefix)
    /// * `crate_info` - Cargo metadata for the target crate
    ///
    /// # Returns
    ///
    /// A vector of candidate file paths, ordered by preference:
    /// 1. For crate root: entry point files (lib.rs, main.rs, or both)
    /// 2. For modules: file.rs first, then file/mod.rs
    ///
    /// # Example
    ///
    /// ```ignore
    /// // Bin-only crate (only main.rs):
    /// let path = SymbolPath::parse("main::my_app::Status")?;
    /// let candidates = resolver.resolve_candidates_with_crate_info(&path, &crate_info);
    /// // → ["src/main.rs"] (crate root, bin-only)
    ///
    /// // Library crate with module:
    /// let path = SymbolPath::parse("my_lib::models::User")?;
    /// let candidates = resolver.resolve_candidates_with_crate_info(&path, &crate_info);
    /// // → ["src/models.rs", "src/models/mod.rs"]
    /// ```
    ///
    /// # See Also
    ///
    /// - [`SymbolPath::module_path_str()`] - Inverse operation (file → symbol path)
    /// - [`SymbolPath::is_main_symbol()`] - Checks for `main::` prefix
    /// - `resolve_crate_root_candidates()` - Handles entry point resolution
    pub fn resolve_candidates_with_crate_info(
        &self,
        path: &SymbolPath,
        crate_info: &CrateInfo,
    ) -> Vec<WorkspaceFilePath> {
        let crate_name = CrateName::new_unchecked(&crate_info.module_name);

        // For main symbols (main::my_crate::Item), skip both "main" and crate name
        // For library symbols (my_crate::Item), skip crate name only
        let skip_count = if path.is_main_symbol() { 2 } else { 1 };
        let segments: Vec<&str> = path.segments().skip(skip_count).collect();

        // Get crate's source directory relative to workspace root
        // e.g., "crates/core/src" or "src"
        let crate_src_path = &crate_info.src_path;

        if segments.is_empty() || segments.len() == 1 {
            // Crate root or crate root item (e.g., crate or crate::Item)
            // Both should resolve to the crate's entry point (lib.rs or main.rs)
            return self.resolve_crate_root_candidates(crate_info, &crate_name);
        }

        // For sub-modules (2+ segments after crate), use crate's src_path as base
        let mut candidates = Vec::with_capacity(2);

        // Build module path relative to crate's src directory
        let mut path_buf = PathBuf::from(crate_src_path.as_str());
        for seg in &segments {
            path_buf.push(seg);
        }

        // Candidate 1: crates/xxx/src/foo/bar.rs
        let mut file_path = path_buf.clone();
        file_path.set_extension("rs");
        candidates.push(
            self.workspace_resolver
                .resolve_relative_with_crate(&file_path, crate_name.clone()),
        );

        // Candidate 2: crates/xxx/src/foo/bar/mod.rs
        let mut mod_path = path_buf;
        mod_path.push("mod.rs");
        candidates.push(
            self.workspace_resolver
                .resolve_relative_with_crate(&mod_path, crate_name),
        );

        candidates
    }

    /// Resolve crate root candidates using entry_points from CrateInfo
    fn resolve_crate_root_candidates(
        &self,
        crate_info: &CrateInfo,
        crate_name: &CrateName,
    ) -> Vec<WorkspaceFilePath> {
        let mut candidates = Vec::new();

        // Check for lib target first (preferred)
        let has_lib = crate_info
            .entry_points
            .iter()
            .any(|t| t.kind == TargetKind::Lib);

        // Check for bin target
        let bin_target = crate_info
            .entry_points
            .iter()
            .find(|t| t.kind == TargetKind::Bin);

        if has_lib {
            // Lib target exists - add lib.rs
            let lib_path = crate_info.src_path.join("lib.rs");
            candidates.push(
                self.workspace_resolver
                    .resolve_relative_with_crate(lib_path.as_str(), crate_name.clone()),
            );
        }

        if let Some(bin) = bin_target {
            // Bin target exists - add its path (usually main.rs but could be custom)
            // Use the actual path from entry_points
            candidates.push(
                self.workspace_resolver
                    .resolve_relative_with_crate(bin.src_path.as_str(), crate_name.clone()),
            );
        }

        // Fallback: if no targets found, use default paths
        if candidates.is_empty() {
            let src_path = &crate_info.src_path;
            candidates.push(
                self.workspace_resolver.resolve_relative_with_crate(
                    format!("{}/lib.rs", src_path),
                    crate_name.clone(),
                ),
            );
            candidates.push(
                self.workspace_resolver.resolve_relative_with_crate(
                    format!("{}/main.rs", src_path),
                    crate_name.clone(),
                ),
            );
        }

        candidates
    }

    /// Resolve using CrateInfo, checking file existence
    ///
    /// Returns the first candidate that exists in the provided file set.
    /// This is the recommended method for production use.
    ///
    /// # Arguments
    ///
    /// * `path` - The symbol path to resolve
    /// * `crate_info` - Cargo metadata for the crate
    /// * `existing_files` - Set of files that exist (for existence checking)
    pub fn resolve_with_crate_info<F>(
        &self,
        path: &SymbolPath,
        crate_info: &CrateInfo,
        file_exists: F,
    ) -> Result<WorkspaceFilePath, ResolutionError>
    where
        F: Fn(&WorkspaceFilePath) -> bool,
    {
        let candidates = self.resolve_candidates_with_crate_info(path, crate_info);

        for candidate in candidates {
            if file_exists(&candidate) {
                return Ok(candidate);
            }
        }

        Err(ResolutionError::SymbolNotFound(format!(
            "No file found for symbol '{}' in crate '{}'",
            path, crate_info.name
        )))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::kind::SymbolKind;
    use crate::span::FileSpan;

    fn make_path(s: &str) -> SymbolPath {
        SymbolPath::parse(s).unwrap()
    }

    fn make_resolver() -> FilePathResolver {
        FilePathResolver::new(PathBuf::from("/workspace"))
    }

    #[test]
    fn test_resolve_crate_root() {
        let resolver = make_resolver();
        let path = make_path("my_crate");

        let result = resolver.resolve_by_inference(&path).unwrap();
        assert_eq!(result.as_relative(), std::path::Path::new("src/lib.rs"));
    }

    #[test]
    fn test_resolve_simple_module() {
        let resolver = make_resolver();
        let path = make_path("my_crate::foo");

        let result = resolver.resolve_by_inference(&path).unwrap();
        assert_eq!(result.as_relative(), std::path::Path::new("src/foo.rs"));
    }

    #[test]
    fn test_resolve_nested_module() {
        let resolver = make_resolver();
        let path = make_path("my_crate::foo::bar");

        let result = resolver.resolve_by_inference(&path).unwrap();
        assert_eq!(result.as_relative(), std::path::Path::new("src/foo/bar.rs"));
    }

    #[test]
    fn test_resolve_item_in_module() {
        let resolver = make_resolver();
        // Item "Baz" in module foo::bar
        let path = make_path("my_crate::foo::bar::Baz");

        let result = resolver.resolve_by_inference(&path).unwrap();
        // Should resolve to the module file
        assert_eq!(
            result.as_relative(),
            std::path::Path::new("src/foo/bar/Baz.rs")
        );
    }

    #[test]
    fn test_resolve_candidates() {
        let resolver = make_resolver();
        let path = make_path("my_crate::foo::bar");

        let candidates = resolver.resolve_candidates(&path);
        assert_eq!(candidates.len(), 2);
        assert_eq!(
            candidates[0].as_relative(),
            std::path::Path::new("src/foo/bar.rs")
        );
        assert_eq!(
            candidates[1].as_relative(),
            std::path::Path::new("src/foo/bar/mod.rs")
        );
    }

    #[test]
    fn test_resolve_with_registry() {
        let resolver = make_resolver();
        let mut registry = SymbolRegistry::new();

        let symbol_path = make_path("my_crate::MyStruct");
        let file = WorkspaceFilePath::new_for_test("src/lib.rs", "/workspace", "my_crate");
        let span = FileSpan::new(file.clone(), 100, 150);

        let id = registry
            .register(symbol_path.clone(), SymbolKind::Struct)
            .unwrap();
        registry.set_span(id, span).unwrap();

        let result = resolver
            .resolve_with_registry(&symbol_path, &registry)
            .unwrap();
        assert_eq!(result, file);
    }

    #[test]
    fn test_resolve_fallback_to_inference() {
        let resolver = make_resolver();
        let registry = SymbolRegistry::new(); // Empty registry

        let path = make_path("my_crate::foo");

        // Symbol not in registry, should fall back to inference
        let result = resolver.resolve(&path, Some(&registry)).unwrap();
        assert_eq!(result.as_relative(), std::path::Path::new("src/foo.rs"));
    }
}