ryo-symbol 0.1.0

//! Workspace metadata provider - CargoMetadataProvider implementation

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

use camino::{Utf8Path, Utf8PathBuf};
use cargo_metadata::{Metadata, MetadataCommand};
use thiserror::Error;

use crate::crate_name::CrateName;
use crate::file_path::WorkspaceFilePath;
use crate::resolver::{CrateLayout, WorkspaceType};

/// Workspace metadata provider trait
///
/// Provides metadata about the workspace, such as crate information.
/// This trait abstracts away the details of how workspace information
/// is obtained.
///
/// # Thread Safety
/// Implementations must be `Send + Sync` for use in multi-threaded contexts.
pub trait WorkspaceMetadataProvider: Send + Sync {
    /// Get the crate name for a file path
    ///
    /// Returns the crate that contains the given file, or None if
    /// the file is not part of any known crate.
    fn crate_for_file(&self, path: &WorkspaceFilePath) -> Option<CrateName>;

    /// Get all crate names in the workspace
    fn all_crates(&self) -> Vec<CrateName>;

    /// Get the root directory of a crate
    fn crate_root(&self, crate_name: &CrateName) -> Option<PathBuf>;

    /// Get the workspace root directory
    fn workspace_root(&self) -> &Path;

    /// Get the CrateLayout for a crate.
    ///
    /// Determines the directory structure of a crate within the workspace.
    /// Used for converting crate-relative paths to workspace-relative paths.
    ///
    /// # Returns
    ///
    /// - `Some(CrateLayout::Root)` - Crate at workspace root
    /// - `Some(CrateLayout::InCrates { .. })` - Crate in `crates/` directory
    /// - `Some(CrateLayout::Custom { .. })` - Crate at custom path
    /// - `None` - Crate not found
    fn crate_layout(&self, crate_name: &CrateName) -> Option<CrateLayout>;
}

/// Error type for CargoMetadataProvider
#[derive(Debug, Error)]
pub enum MetadataError {
    /// The expected `Cargo.toml` file does not exist at the given path.
    #[error("manifest not found: {0}")]
    ManifestNotFound(PathBuf),

    /// `cargo metadata` invocation failed (I/O, parse, or non-zero exit).
    #[error("cargo metadata failed: {0}")]
    CargoMetadata(#[from] cargo_metadata::Error),

    /// The requested path is not within the resolved workspace root, so no
    /// crate mapping can be produced for it.
    #[error("path is outside workspace: {0}")]
    OutsideWorkspace(PathBuf),
}

/// Information about a crate in the workspace
#[derive(Debug, Clone)]
pub struct CrateInfo {
    /// Crate name (e.g., "ryo-app")
    pub name: String,
    /// Module name (hyphens → underscores, e.g., "ryo_app")
    pub module_name: String,
    /// Path to Cargo.toml
    pub manifest_path: Utf8PathBuf,
    /// Root source directory (typically "src")
    pub src_path: Utf8PathBuf,
    /// Is this a workspace member (vs external dependency)
    pub is_workspace_member: bool,
    /// Entry points (lib.rs, main.rs, etc.) from Cargo targets
    pub entry_points: Vec<TargetInfo>,
}

/// Information about a cargo target (lib, bin, etc.)
#[derive(Debug, Clone)]
pub struct TargetInfo {
    /// Target name
    pub name: String,
    /// Target kind ("lib", "bin", "example", "test", "bench")
    pub kind: TargetKind,
    /// Path to source file (e.g., src/lib.rs, src/main.rs)
    pub src_path: Utf8PathBuf,
}

/// Kind of cargo target
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum TargetKind {
    /// Library target (`[lib]`), including rlib / dylib / cdylib / staticlib
    /// / proc-macro flavors collapsed into one bucket.
    Lib,
    /// Binary target (`[[bin]]`).
    Bin,
    /// Example target under `examples/`.
    Example,
    /// Integration test target under `tests/`.
    Test,
    /// Benchmark target under `benches/`.
    Bench,
    /// Any cargo target kind not recognized by this crate (forward-compat
    /// catch-all for new Cargo target kinds added upstream).
    Other,
}

impl TargetKind {
    fn from_cargo_kinds(kinds: &[cargo_metadata::TargetKind]) -> Self {
        use cargo_metadata::TargetKind as CK;
        for kind in kinds {
            match kind {
                CK::Lib | CK::RLib | CK::DyLib | CK::CDyLib | CK::StaticLib | CK::ProcMacro => {
                    return Self::Lib
                }
                CK::Bin => return Self::Bin,
                CK::Example => return Self::Example,
                CK::Test => return Self::Test,
                CK::Bench => return Self::Bench,
                _ => {}
            }
        }
        Self::Other
    }
}

/// Cargo metadata based workspace provider
///
/// This is the default implementation of `WorkspaceMetadataProvider`.
/// It uses `cargo metadata` to discover workspace structure and
/// map file paths to crate names.
///
/// # Example
/// ```ignore
/// use ryo_symbol::{CargoMetadataProvider, WorkspaceMetadataProvider};
///
/// let provider = CargoMetadataProvider::from_manifest("Cargo.toml")?;
///
/// // Get crate name for a file
/// let path = provider.resolver().resolve("crates/ryo-app/src/lib.rs")?;
/// let crate_name = provider.crate_for_file(&path);
/// ```
#[derive(Debug)]
pub struct CargoMetadataProvider {
    /// Workspace root directory
    workspace_root: Utf8PathBuf,
    /// All crates in the workspace (by name)
    crates: HashMap<String, CrateInfo>,
    /// File path prefix → crate name mapping (for fast lookup)
    path_to_crate: Vec<(Utf8PathBuf, String)>,
    /// Workspace type (Workspace or Crate)
    workspace_type: WorkspaceType,
}

impl CargoMetadataProvider {
    /// Create a provider from a Cargo.toml path
    pub fn from_manifest(manifest_path: impl AsRef<Path>) -> Result<Self, MetadataError> {
        let manifest_path = manifest_path.as_ref();

        if !manifest_path.exists() {
            return Err(MetadataError::ManifestNotFound(manifest_path.to_path_buf()));
        }

        let metadata = MetadataCommand::new()
            .manifest_path(manifest_path)
            .no_deps() // Only workspace members, faster
            .exec()?;

        Self::from_metadata(metadata)
    }

    /// Create a provider from a directory containing Cargo.toml
    pub fn from_directory(dir: impl AsRef<Path>) -> Result<Self, MetadataError> {
        let dir = dir.as_ref();
        let manifest_path = dir.join("Cargo.toml");
        Self::from_manifest(manifest_path)
    }

    /// Create a provider from pre-fetched metadata
    pub fn from_metadata(metadata: Metadata) -> Result<Self, MetadataError> {
        let workspace_root = metadata.workspace_root.clone();
        let workspace_members: std::collections::HashSet<_> =
            metadata.workspace_members.iter().collect();

        let mut crates = HashMap::new();
        let mut path_to_crate = Vec::new();

        for pkg in &metadata.packages {
            let is_member = workspace_members.contains(&pkg.id);
            let manifest_dir = pkg.manifest_path.parent().unwrap_or(&pkg.manifest_path);
            let src_path_absolute = manifest_dir.join("src");

            // Convert to relative path from workspace root
            let src_path = src_path_absolute
                .strip_prefix(&workspace_root)
                .unwrap_or(&src_path_absolute)
                .to_path_buf();

            // Collect entry points from targets
            let entry_points: Vec<TargetInfo> = pkg
                .targets
                .iter()
                .map(|target| {
                    // Convert target src_path to relative
                    let target_src_relative = target
                        .src_path
                        .strip_prefix(&workspace_root)
                        .unwrap_or(&target.src_path)
                        .to_path_buf();
                    TargetInfo {
                        name: target.name.clone(),
                        kind: TargetKind::from_cargo_kinds(&target.kind),
                        src_path: target_src_relative,
                    }
                })
                .collect();

            let info = CrateInfo {
                name: pkg.name.clone(),
                module_name: pkg.name.replace('-', "_"),
                manifest_path: pkg.manifest_path.clone(),
                src_path: src_path.clone(),
                is_workspace_member: is_member,
                entry_points,
            };

            // Only index workspace members for path resolution
            if is_member {
                path_to_crate.push((src_path, info.module_name.clone()));
            }

            crates.insert(pkg.name.clone(), info);
        }

        // Sort by path length (longest first) for prefix matching
        path_to_crate.sort_by_key(|b| std::cmp::Reverse(b.0.as_str().len()));

        // Determine workspace type:
        // - Multiple members → Workspace
        // - Single member at workspace_root (manifest in root) → Crate
        // - Single member in subdirectory → Workspace
        let workspace_type = if workspace_members.len() > 1 {
            WorkspaceType::Workspace
        } else if let Some(pkg) = metadata
            .packages
            .iter()
            .find(|p| workspace_members.contains(&p.id))
        {
            // Check if the single member's manifest is at workspace root
            let manifest_dir = pkg.manifest_path.parent().unwrap_or(&pkg.manifest_path);
            if manifest_dir == workspace_root {
                WorkspaceType::Crate
            } else {
                WorkspaceType::Workspace
            }
        } else {
            WorkspaceType::Workspace
        };

        Ok(Self {
            workspace_root,
            crates,
            path_to_crate,
            workspace_type,
        })
    }

    /// Get crate info by name
    pub fn get_crate(&self, name: &str) -> Option<&CrateInfo> {
        self.crates.get(name)
    }

    /// Get the CrateLayout for a crate by module name.
    ///
    /// Determines the directory structure of a crate within the workspace
    /// based on its `src_path`. This is essential for converting crate-relative
    /// paths (e.g., `"src/lib.rs"`) to workspace-relative paths
    /// (e.g., `"crates/my-crate/src/lib.rs"`).
    ///
    /// # Returns
    ///
    /// - `Some(CrateLayout::Root)` - Crate at workspace root (`src/lib.rs`)
    /// - `Some(CrateLayout::InCrates { .. })` - Crate in `crates/` directory
    /// - `Some(CrateLayout::Custom { .. })` - Crate at custom path
    /// - `None` - Crate not found in workspace
    ///
    /// # Example
    ///
    /// ```ignore
    /// let provider = CargoMetadataProvider::from_directory(".")?;
    /// let crate_name = CrateName::new("my_crate")?;
    ///
    /// match provider.crate_layout(&crate_name) {
    ///     Some(CrateLayout::Root) => println!("Crate at workspace root"),
    ///     Some(CrateLayout::InCrates { crate_dir_name }) => {
    ///         println!("Crate in crates/{}", crate_dir_name);
    ///     }
    ///     Some(CrateLayout::Custom { prefix }) => {
    ///         println!("Crate at {}", prefix.display());
    ///     }
    ///     None => println!("Crate not found"),
    /// }
    /// ```
    pub fn crate_layout(&self, crate_name: &CrateName) -> Option<CrateLayout> {
        // Find crate by module name (underscores)
        let module_name = crate_name.to_module_name();
        let info = self
            .crates
            .values()
            .find(|c| c.module_name == module_name && c.is_workspace_member)?;

        // Analyze src_path to determine layout
        let src_path = info.src_path.as_str();

        // Pattern 1: "src" → Root (crate at workspace root)
        if src_path == "src" {
            return Some(CrateLayout::Root);
        }

        // Pattern 2: "crates/{name}/src" → InCrates
        if let Some(rest) = src_path.strip_prefix("crates/") {
            if let Some(crate_dir) = rest.strip_suffix("/src") {
                return Some(CrateLayout::InCrates {
                    crate_dir_name: crate_dir.to_string(),
                });
            }
        }

        // Pattern 3: "{prefix}/src" → Custom
        if let Some(prefix) = src_path.strip_suffix("/src") {
            return Some(CrateLayout::Custom {
                prefix: PathBuf::from(prefix),
            });
        }

        // Fallback: treat entire src_path as custom prefix
        Some(CrateLayout::Custom {
            prefix: PathBuf::from(src_path),
        })
    }

    /// Get the workspace type
    pub fn workspace_type(&self) -> WorkspaceType {
        self.workspace_type
    }

    /// Get all workspace members
    pub fn members(&self) -> impl Iterator<Item = &CrateInfo> {
        self.crates.values().filter(|c| c.is_workspace_member)
    }

    /// Check if a path is within the workspace
    pub fn is_in_workspace(&self, path: impl AsRef<Path>) -> bool {
        let path = path.as_ref();
        path.to_str()
            .map(|s| Utf8Path::new(s).starts_with(&self.workspace_root))
            .unwrap_or(false)
    }

    /// Get the module path within a crate for a file
    ///
    /// Example: "crates/ryo-app/src/config/mod.rs" → "config"
    pub fn module_path_for_file(&self, file_path: impl AsRef<Path>) -> Option<String> {
        let file_path = file_path.as_ref();
        let file_path_str = file_path.to_str()?;
        let file_path = Utf8Path::new(file_path_str);

        let file_path = if file_path.is_relative() {
            self.workspace_root.join(file_path)
        } else {
            file_path.to_path_buf()
        };

        // Find matching crate
        for (src_path, _) in &self.path_to_crate {
            if file_path.starts_with(src_path) {
                // Get relative path within src
                let relative = file_path.strip_prefix(src_path).ok()?;
                let relative_str = relative.as_str();

                // Remove .rs extension
                let module_path = relative_str.trim_end_matches(".rs");

                // Convert path separators to ::
                let module_path = module_path.replace('/', "::");

                // Handle lib.rs and mod.rs
                let module_path = if module_path == "lib" || module_path.is_empty() {
                    String::new()
                } else if module_path.ends_with("::mod") {
                    module_path.trim_end_matches("::mod").to_string()
                } else {
                    module_path
                };

                return Some(module_path);
            }
        }

        None
    }

    /// Get the full symbol path for a file
    ///
    /// Example: "crates/ryo-app/src/config/mod.rs" → "ryo_app::config"
    pub fn symbol_path_for_file(&self, file_path: impl AsRef<Path>) -> Option<String> {
        let file_path = file_path.as_ref();
        let file_path_str = file_path.to_str()?;
        let utf8_path = Utf8Path::new(file_path_str);

        let canonical_path = if utf8_path.is_relative() {
            self.workspace_root.join(utf8_path)
        } else {
            utf8_path.to_path_buf()
        };

        // Find crate name
        for (src_path, module_name) in &self.path_to_crate {
            if canonical_path.starts_with(src_path) {
                let module_path = self.module_path_for_file(file_path)?;
                return if module_path.is_empty() {
                    Some(module_name.clone())
                } else {
                    Some(format!("{}::{}", module_name, module_path))
                };
            }
        }

        None
    }

    /// Get internal crate name lookup (for trait implementation)
    fn crate_name_for_path(&self, file_path: &Path) -> Option<&str> {
        let file_path_str = file_path.to_str()?;
        let file_path = Utf8Path::new(file_path_str);

        // Convert to absolute path
        let file_path_absolute = if file_path.is_relative() {
            self.workspace_root.join(file_path)
        } else {
            file_path.to_path_buf()
        };

        // Find matching crate by src path prefix
        // Note: path_to_crate contains relative paths (relative to workspace_root)
        for (src_path, module_name) in &self.path_to_crate {
            // Convert src_path to absolute for comparison
            let src_path_absolute = self.workspace_root.join(src_path);
            if file_path_absolute.starts_with(&src_path_absolute) {
                return Some(module_name.as_str());
            }
        }

        None
    }
}

impl WorkspaceMetadataProvider for CargoMetadataProvider {
    fn crate_for_file(&self, path: &WorkspaceFilePath) -> Option<CrateName> {
        let absolute = path.to_absolute();
        let module_name = self.crate_name_for_path(&absolute)?;
        Some(CrateName::new_unchecked(module_name))
    }

    fn all_crates(&self) -> Vec<CrateName> {
        self.crates
            .values()
            .filter(|c| c.is_workspace_member)
            .map(|c| CrateName::new_unchecked(&c.module_name))
            .collect()
    }

    fn crate_root(&self, crate_name: &CrateName) -> Option<PathBuf> {
        // Try to find by module name first (underscores)
        let module_name = crate_name.to_module_name();

        for info in self.crates.values() {
            if info.module_name == module_name {
                return info
                    .manifest_path
                    .parent()
                    .map(|p| PathBuf::from(p.as_str()));
            }
        }

        // Try by cargo name (hyphens)
        self.crates
            .get(crate_name.as_str())
            .and_then(|info| info.manifest_path.parent())
            .map(|p| PathBuf::from(p.as_str()))
    }

    fn workspace_root(&self) -> &Path {
        self.workspace_root.as_std_path()
    }

    fn crate_layout(&self, crate_name: &CrateName) -> Option<CrateLayout> {
        // Delegate to the inherent method
        CargoMetadataProvider::crate_layout(self, crate_name)
    }
}

/// Mock metadata provider for testing
///
/// Provides a simple in-memory implementation of `WorkspaceMetadataProvider`
/// that returns a fixed crate name for all files.
///
/// # Example
/// ```ignore
/// use ryo_symbol::{MockMetadataProvider, WorkspaceMetadataProvider};
///
/// let provider = MockMetadataProvider::new("/workspace", "mylib");
/// let path = WorkspaceFilePath::new_for_test("src/lib.rs", "/workspace");
/// assert_eq!(provider.crate_for_file(&path).unwrap().as_str(), "mylib");
/// ```
#[cfg(any(test, feature = "test-utils"))]
#[derive(Debug, Clone)]
pub struct MockMetadataProvider {
    workspace_root: PathBuf,
    crate_name: CrateName,
}

#[cfg(any(test, feature = "test-utils"))]
impl MockMetadataProvider {
    /// Create a new mock provider with a fixed crate name
    pub fn new(workspace_root: impl Into<PathBuf>, crate_name: impl AsRef<str>) -> Self {
        Self {
            workspace_root: workspace_root.into(),
            crate_name: CrateName::new_unchecked(crate_name.as_ref()),
        }
    }
}

#[cfg(any(test, feature = "test-utils"))]
impl WorkspaceMetadataProvider for MockMetadataProvider {
    fn crate_for_file(&self, _path: &WorkspaceFilePath) -> Option<CrateName> {
        Some(self.crate_name.clone())
    }

    fn all_crates(&self) -> Vec<CrateName> {
        vec![self.crate_name.clone()]
    }

    fn crate_root(&self, _crate_name: &CrateName) -> Option<PathBuf> {
        Some(self.workspace_root.clone())
    }

    fn workspace_root(&self) -> &Path {
        &self.workspace_root
    }

    fn crate_layout(&self, _crate_name: &CrateName) -> Option<CrateLayout> {
        // Mock always returns Root layout
        Some(CrateLayout::Root)
    }
}

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

    // ========================================================================
    // crate_layout() tests - TDD RED phase
    // ========================================================================

    #[test]
    fn test_crate_layout_root_crate() {
        // Single crate at workspace root: src/lib.rs
        // src_path = "src" (relative to workspace root)
        let provider = create_test_provider_with_src_path("my_crate", "src");
        let crate_name = CrateName::new_unchecked("my_crate");

        let layout = provider.crate_layout(&crate_name);

        assert_eq!(layout, Some(CrateLayout::Root));
    }

    #[test]
    fn test_crate_layout_in_crates_directory() {
        // Crate in crates/ directory: crates/my-crate/src/lib.rs
        // src_path = "crates/my-crate/src" (relative to workspace root)
        let provider = create_test_provider_with_src_path("my_crate", "crates/my-crate/src");
        let crate_name = CrateName::new_unchecked("my_crate");

        let layout = provider.crate_layout(&crate_name);

        assert_eq!(
            layout,
            Some(CrateLayout::InCrates {
                crate_dir_name: "my-crate".to_string()
            })
        );
    }

    #[test]
    fn test_crate_layout_custom_path() {
        // Crate at custom path: packages/core/src/lib.rs
        // src_path = "packages/core/src" (relative to workspace root)
        let provider = create_test_provider_with_src_path("core", "packages/core/src");
        let crate_name = CrateName::new_unchecked("core");

        let layout = provider.crate_layout(&crate_name);

        assert_eq!(
            layout,
            Some(CrateLayout::Custom {
                prefix: PathBuf::from("packages/core")
            })
        );
    }

    #[test]
    fn test_crate_layout_unknown_crate_returns_none() {
        let provider = create_test_provider_with_src_path("my_crate", "src");
        let crate_name = CrateName::new_unchecked("unknown_crate");

        let layout = provider.crate_layout(&crate_name);

        assert_eq!(layout, None);
    }

    /// Helper: Create a test provider with specified src_path
    fn create_test_provider_with_src_path(
        module_name: &str,
        src_path: &str,
    ) -> CargoMetadataProvider {
        let workspace_root = Utf8PathBuf::from("/workspace");
        let mut crates = HashMap::new();

        let info = CrateInfo {
            name: module_name.replace('_', "-"),
            module_name: module_name.to_string(),
            manifest_path: Utf8PathBuf::from(format!(
                "/workspace/{}/Cargo.toml",
                src_path.trim_end_matches("/src")
            )),
            src_path: Utf8PathBuf::from(src_path),
            is_workspace_member: true,
            entry_points: vec![],
        };

        crates.insert(info.name.clone(), info.clone());

        let path_to_crate = vec![(Utf8PathBuf::from(src_path), module_name.to_string())];

        CargoMetadataProvider {
            workspace_root,
            crates,
            path_to_crate,
            workspace_type: WorkspaceType::Workspace,
        }
    }

    // ========================================================================
    // Existing tests
    // ========================================================================

    #[test]
    fn test_crate_info() {
        let info = CrateInfo {
            name: "ryo-app".to_string(),
            module_name: "ryo_app".to_string(),
            manifest_path: Utf8PathBuf::from("/test/Cargo.toml"),
            src_path: Utf8PathBuf::from("/test/src"),
            is_workspace_member: true,
            entry_points: vec![TargetInfo {
                name: "ryo_app".to_string(),
                kind: TargetKind::Lib,
                src_path: Utf8PathBuf::from("/test/src/lib.rs"),
            }],
        };

        assert_eq!(info.module_name, "ryo_app");
        assert!(info.is_workspace_member);
        assert_eq!(info.entry_points.len(), 1);
    }

    #[test]
    fn test_mock_provider() {
        let provider = MockMetadataProvider::new("/workspace", "mylib");
        let path = WorkspaceFilePath::new_for_test("src/lib.rs", "/workspace", "mylib");

        assert_eq!(provider.crate_for_file(&path).unwrap().as_str(), "mylib");
        assert_eq!(provider.workspace_root(), Path::new("/workspace"));
        assert_eq!(provider.all_crates().len(), 1);
    }
}