cargo-rail 0.13.2

//! Graph-aware change impact analysis
//!
//! This module provides intelligent change detection by combining:
//! - Git file-level changes
//! - Advanced file classification
//! - Workspace dependency graph
//! - Cargo package metadata

use crate::error::RailResult;
use crate::workspace::WorkspaceContext;
use std::collections::HashSet;
use std::path::Path;
use std::path::PathBuf;

use crate::change_detection::classify::{FileProfile, classify_path};

/// Categorization of changed files by type
#[derive(Debug, Default)]
pub struct ChangeCategories {
  /// Source code files
  pub source_files: Vec<PathBuf>,
  /// Test files
  pub test_files: Vec<PathBuf>,
  /// Example files
  pub example_files: Vec<PathBuf>,
  /// Documentation files
  pub doc_files: Vec<PathBuf>,
  /// Configuration files
  pub config_files: Vec<PathBuf>,
  /// Build scripts
  pub build_scripts: Vec<PathBuf>,
  /// Other files
  pub other_files: Vec<PathBuf>,
}

impl ChangeCategories {
  /// Check if only documentation files changed
  pub fn is_docs_only(&self) -> bool {
    self.source_files.is_empty()
      && self.test_files.is_empty()
      && self.example_files.is_empty()
      && self.config_files.is_empty()
      && self.build_scripts.is_empty()
      && !self.doc_files.is_empty()
  }

  /// Check if any source code changed (requires rebuild)
  pub fn has_source_changes(&self) -> bool {
    !self.source_files.is_empty() || !self.build_scripts.is_empty()
  }

  /// Check if any tests changed (requires re-test)
  pub fn has_test_changes(&self) -> bool {
    !self.test_files.is_empty()
  }

  /// Check if configuration changed (may affect dependencies)
  pub fn has_config_changes(&self) -> bool {
    !self.config_files.is_empty()
  }

  /// Check if any examples changed
  pub fn has_example_changes(&self) -> bool {
    !self.example_files.is_empty()
  }
}

/// Comprehensive change impact report
#[derive(Debug)]
pub struct ImpactReport {
  /// All changed files with their change types (A/M/D)
  pub changed_files: Vec<(PathBuf, char)>,

  /// Workspace crates directly containing changed files
  pub direct_crates: Vec<String>,

  /// Crates transitively depending on direct_crates
  pub transitive_crates: Vec<String>,

  /// Categorization of changes
  pub categories: ChangeCategories,

  /// Whether changes require rebuild
  pub requires_rebuild: bool,

  /// Whether changes require re-testing
  pub requires_retest: bool,
}

impl ImpactReport {
  /// Get complete set of affected crates (direct + transitive)
  pub fn all_affected_crates(&self) -> Vec<String> {
    let mut all: HashSet<String> = self.direct_crates.iter().cloned().collect();
    all.extend(self.transitive_crates.iter().cloned());
    let mut result: Vec<_> = all.into_iter().collect();
    result.sort();
    result
  }

  /// Check if a specific crate is affected
  pub fn affects_crate(&self, crate_name: &str) -> bool {
    self.direct_crates.iter().any(|name| name == crate_name)
      || self.transitive_crates.iter().any(|name| name == crate_name)
  }

  /// Get minimal test set (only affected crates)
  pub fn minimal_test_set(&self) -> Vec<String> {
    self.all_affected_crates()
  }
}

/// Graph-aware change impact analyzer
pub struct ChangeImpact<'a> {
  ctx: &'a WorkspaceContext,
}

impl<'a> ChangeImpact<'a> {
  /// Create new analyzer from workspace context
  pub fn new(ctx: &'a WorkspaceContext) -> Self {
    Self { ctx }
  }

  /// Analyze changes between two git refs with full graph awareness
  ///
  /// If `to` is None, compares against the working tree (uncommitted changes).
  pub fn analyze_changes(&self, from: &str, to: Option<&str>) -> RailResult<ImpactReport> {
    // 1. Get changed files from git (paths are relative to git root)
    let git_changed_files = self.ctx.git()?.git().get_changed_files_between(from, to)?;

    // 2. Convert git-relative paths to workspace-relative paths
    //    This handles nested workspaces (e.g., git at /repo, workspace at /repo/rust)
    let changed_files: Vec<(PathBuf, char)> = git_changed_files
      .into_iter()
      .filter_map(|(git_path, change_type)| {
        self
          .ctx
          .to_workspace_path(&git_path)
          .map(|ws_path| (ws_path, change_type))
      })
      .collect();

    // 3. Categorize changes by file type using new classification system
    let categories = self.categorize_changes(&changed_files);

    // 4. Use graph to find affected crates
    let file_paths: Vec<&Path> = changed_files.iter().map(|(p, _)| p.as_path()).collect();
    let analysis = crate::graph::analyze(&self.ctx.graph, &file_paths)?;

    // 5. Determine rebuild/retest requirements
    let requires_rebuild = categories.has_source_changes() || categories.has_config_changes();
    let requires_retest = requires_rebuild || categories.has_test_changes() || categories.has_example_changes();

    // Convert HashSets to Vecs
    let mut direct_crates: Vec<String> = analysis.impact.direct.into_iter().collect();
    direct_crates.sort();

    let mut transitive_crates: Vec<String> = analysis.impact.dependents.into_iter().collect();
    transitive_crates.sort();

    Ok(ImpactReport {
      changed_files,
      direct_crates,
      transitive_crates,
      categories,
      requires_rebuild,
      requires_retest,
    })
  }

  /// Analyze changes for a specific crate only
  pub fn analyze_crate_changes(
    &self,
    crate_name: &str,
    from: &str,
    to: Option<&str>,
  ) -> RailResult<Option<ImpactReport>> {
    let full_report = self.analyze_changes(from, to)?;

    // Filter to only this crate
    if !full_report.affects_crate(crate_name) {
      return Ok(None);
    }

    Ok(Some(full_report))
  }

  /// Categorize changed files using advanced classification
  fn categorize_changes(&self, files: &[(PathBuf, char)]) -> ChangeCategories {
    let mut categories = ChangeCategories::default();

    for (path, _change_type) in files {
      match classify_path(path) {
        FileProfile::RustSrc => categories.source_files.push(path.clone()),
        FileProfile::RustTest | FileProfile::RustBench => categories.test_files.push(path.clone()),
        FileProfile::RustExample => categories.example_files.push(path.clone()),
        FileProfile::RustBuildScript => categories.build_scripts.push(path.clone()),
        FileProfile::TomlManifest
        | FileProfile::TomlWorkspace
        | FileProfile::TomlCargoConfig
        | FileProfile::TomlRustToolchain
        | FileProfile::TomlTooling
        | FileProfile::CargoLock => {
          categories.config_files.push(path.clone());
        }
        FileProfile::Docs | FileProfile::RepoConfig => categories.doc_files.push(path.clone()),
        FileProfile::Ci | FileProfile::Script | FileProfile::Unknown => categories.other_files.push(path.clone()),
      }
    }

    categories
  }
}

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

  fn create_test_context() -> WorkspaceContext {
    let current_dir = std::env::current_dir().unwrap();
    WorkspaceContext::build(&current_dir).unwrap()
  }

  #[test]
  fn test_proc_macro_detection() {
    let ctx = create_test_context();

    // cargo-rail is not a proc-macro crate
    // Use the new cached API for O(1) lookup
    assert!(
      !ctx.cargo.is_proc_macro("cargo-rail"),
      "cargo-rail should not be detected as proc-macro crate"
    );

    // The proc_macro_crates set should be accessible
    let proc_macros = ctx.cargo.proc_macro_crates();
    assert!(
      !proc_macros.contains("cargo-rail"),
      "cargo-rail should not be in proc_macro_crates set"
    );
  }

  #[test]
  fn test_change_categories_docs_only() {
    let mut cat = ChangeCategories::default();
    cat.doc_files.push(PathBuf::from("README.md"));

    assert!(cat.is_docs_only());
    assert!(!cat.has_source_changes());
    assert!(!cat.has_test_changes());
  }

  #[test]
  fn test_change_categories_source_changes() {
    let mut cat = ChangeCategories::default();
    cat.source_files.push(PathBuf::from("src/lib.rs"));

    assert!(!cat.is_docs_only());
    assert!(cat.has_source_changes());
  }

  #[test]
  fn test_change_categories_example_changes() {
    let mut cat = ChangeCategories::default();
    cat.example_files.push(PathBuf::from("examples/demo.rs"));

    assert!(!cat.is_docs_only());
    assert!(cat.has_example_changes());
    assert!(!cat.has_source_changes());
  }

  #[test]
  fn test_categorize_comprehensive() {
    let ctx = create_test_context();
    let analyzer = ChangeImpact::new(&ctx);

    let files = vec![
      (PathBuf::from("src/lib.rs"), 'M'),
      (PathBuf::from("tests/integration.rs"), 'M'),
      (PathBuf::from("examples/demo.rs"), 'M'),
      (PathBuf::from("README.md"), 'M'),
      (PathBuf::from("Cargo.toml"), 'M'),
      (PathBuf::from("build.rs"), 'M'),
      (PathBuf::from(".cargo/config.toml"), 'M'),
    ];

    let cat = analyzer.categorize_changes(&files);

    assert_eq!(cat.source_files.len(), 1, "Expected 1 source file");
    assert_eq!(cat.test_files.len(), 1, "Expected 1 test file");
    assert_eq!(cat.example_files.len(), 1, "Expected 1 example file");
    assert_eq!(cat.doc_files.len(), 1, "Expected 1 doc file");
    assert_eq!(
      cat.config_files.len(),
      2,
      "Expected 2 config files (Cargo.toml + .cargo/config.toml)"
    );
    assert_eq!(cat.build_scripts.len(), 1, "Expected 1 build script");
  }
}