//! Watch Mode Tests - London TDD Style
//!
//! These tests define the expected behavior for file watching and automatic regeneration.
//! They use mocks extensively (London School TDD) to test in isolation.
//!
//! All tests are designed to FAIL initially until the watch mode implementation exists.

use mockall::mock;
use mockall::predicate::*;
use std::path::{Path, PathBuf};
use std::sync::{Arc, Mutex};
use std::time::Duration;
use tempfile::TempDir;

// Mock traits that will guide implementation

/// Mock for file system watcher
mock! {
    pub FileWatcher {
        fn new<P: AsRef<Path> + 'static>(path: P) -> Result<Self, WatchError>;
        fn watch(&mut self) -> Result<(), WatchError>;
        fn set_debounce(&mut self, duration: Duration);
        fn on_change<F>(&mut self, callback: F) where F: Fn(WatchEvent) + Send + 'static;
        fn stop(&mut self) -> Result<(), WatchError>;
    }
}

/// Mock for template regeneration service
mock! {
    pub RegenerationService {
        fn new() -> Self;
        fn regenerate_template<P: AsRef<Path> + 'static>(&self, template_path: P) -> Result<(), RegenerationError>;
        fn regenerate_affected<P: AsRef<Path> + 'static>(&self, changed_file: P) -> Result<Vec<PathBuf>, RegenerationError>;
        fn get_affected_templates<P: AsRef<Path> + 'static>(&self, file_path: P) -> Vec<PathBuf>;
    }
}

/// Mock for dependency graph service
mock! {
    pub DependencyGraph {
        fn new() -> Self;
        fn build_graph<P: AsRef<Path> + 'static>(&mut self, project_root: P) -> Result<(), GraphError>;
        fn get_dependents<P: AsRef<Path> + 'static>(&self, file_path: P) -> Vec<PathBuf>;
        fn is_rdf_file<P: AsRef<Path> + 'static>(&self, file_path: P) -> bool;
        fn is_template_file<P: AsRef<Path> + 'static>(&self, file_path: P) -> bool;
        fn is_query_file<P: AsRef<Path> + 'static>(&self, file_path: P) -> bool;
    }
}

/// Mock for event filter
mock! {
    pub EventFilter {
        fn new() -> Self;
        fn should_ignore<P: AsRef<Path> + 'static>(&self, path: P) -> bool;
        fn add_ignore_pattern(&mut self, pattern: &str);
        fn is_generated_directory<P: AsRef<Path> + 'static>(&self, path: P) -> bool;
    }
}

// Error types that will be needed in implementation
#[derive(Debug, Clone, PartialEq)]
pub enum WatchError {
    NotifyError(String),
    InvalidPath(String),
    AlreadyWatching,
}

#[derive(Debug, Clone, PartialEq)]
pub enum RegenerationError {
    TemplateNotFound(String),
    RenderFailed(String),
    IoError(String),
}

#[derive(Debug, Clone, PartialEq)]
pub enum GraphError {
    ParseError(String),
    InvalidGraph(String),
}

// Event types for watch notifications
#[derive(Debug, Clone, PartialEq)]
pub enum WatchEvent {
    Created(PathBuf),
    Modified(PathBuf),
    Deleted(PathBuf),
    Renamed { from: PathBuf, to: PathBuf },
}

// Test fixtures and helpers
struct WatchTestFixture {
    temp_dir: TempDir,
    project_root: PathBuf,
}

impl WatchTestFixture {
    fn new() -> Self {
        let temp_dir = TempDir::new().expect("Failed to create temp dir");
        let project_root = temp_dir.path().to_path_buf();

        // Create standard project structure
        std::fs::create_dir_all(project_root.join("templates")).unwrap();
        std::fs::create_dir_all(project_root.join("rdf")).unwrap();
        std::fs::create_dir_all(project_root.join("queries")).unwrap();
        std::fs::create_dir_all(project_root.join("generated")).unwrap();

        Self {
            temp_dir,
            project_root,
        }
    }

    fn create_rdf_file(&self, name: &str) -> PathBuf {
        let path = self.project_root.join("rdf").join(name);
        std::fs::write(&path, "<rdf:RDF></rdf:RDF>").unwrap();
        path
    }

    fn create_template_file(&self, name: &str) -> PathBuf {
        let path = self.project_root.join("templates").join(name);
        std::fs::write(&path, "{{ data }}").unwrap();
        path
    }

    fn create_query_file(&self, name: &str) -> PathBuf {
        let path = self.project_root.join("queries").join(name);
        std::fs::write(&path, "SELECT * WHERE { ?s ?p ?o }").unwrap();
        path
    }
}

// =============================================================================
// TEST 1: Detect RDF file changes
// =============================================================================

/// # Phase 2: Watch Service Implementation
///
/// This test defines the expected behavior for detecting RDF file changes.
/// Implementation will require WatchService infrastructure and file system monitoring.
#[tokio::test]
#[ignore = "Phase 2: WatchService not yet implemented"]
async fn test_watch_detects_rdf_file_changes() {
    // ARRANGE: Set up mock watcher and dependency graph
    let fixture = WatchTestFixture::new();
    let rdf_file = fixture.create_rdf_file("data.ttl");

    let mut mock_watcher = MockFileWatcher::new();
    let mut mock_graph = MockDependencyGraph::new();
    let mock_regen = MockRegenerationService::new();

    // Expect dependency graph to be queried
    mock_graph
        .expect_is_rdf_file()
        .with(eq(rdf_file.clone()))
        .times(1)
        .returning(|_| true);

    mock_graph
        .expect_get_dependents()
        .with(eq(rdf_file.clone()))
        .times(1)
        .returning(|_| vec![PathBuf::from("templates/output.md")]);

    // Expect watcher to be configured and started
    mock_watcher.expect_watch().times(1).returning(|| Ok(()));

    let event_triggered = Arc::new(Mutex::new(false));
    let event_triggered_clone = event_triggered.clone();

    mock_watcher
        .expect_on_change()
        .times(1)
        .returning(move |_callback| {
            *event_triggered_clone.lock().unwrap() = true;
        });

    // ACT: Start watching and simulate RDF file change
    // TODO: Implement WatchService and integrate with mocks
    unimplemented!("WatchService::start() not yet implemented");

    // ASSERT: Verify event was detected
    // assert!(*event_triggered.lock().unwrap(), "RDF file change should trigger event");
}

// =============================================================================
// TEST 2: Detect template file changes
// =============================================================================

/// # Phase 2: Template Watch Implementation
///
/// This test defines the expected behavior for detecting and regenerating template files.
#[tokio::test]
#[ignore = "Phase 2: Template watch not yet implemented"]
async fn test_watch_detects_template_file_changes() {
    // ARRANGE: Set up mocks for template watching
    let fixture = WatchTestFixture::new();
    let template_file = fixture.create_template_file("template.md");

    let mut mock_watcher = MockFileWatcher::new();
    let mut mock_graph = MockDependencyGraph::new();
    let mut mock_regen = MockRegenerationService::new();

    mock_graph
        .expect_is_template_file()
        .with(eq(template_file.clone()))
        .times(1)
        .returning(|_| true);

    // When template changes, it should regenerate itself
    mock_regen
        .expect_regenerate_template()
        .with(eq(template_file.clone()))
        .times(1)
        .returning(|_| Ok(()));

    mock_watcher.expect_watch().times(1).returning(|| Ok(()));

    // ACT: Start watching and trigger template change
    unimplemented!("WatchService not yet implemented");

    // ASSERT: Verify regeneration was triggered
}

// =============================================================================
// TEST 3: Detect query file changes
// =============================================================================

/// # Phase 2: Query File Watch Implementation
///
/// This test defines the expected behavior for detecting SPARQL query file changes.
#[tokio::test]
#[ignore = "Phase 2: Query file watching not yet implemented"]
async fn test_watch_detects_query_file_changes() {
    // ARRANGE: Set up mocks for query watching
    let fixture = WatchTestFixture::new();
    let query_file = fixture.create_query_file("list.sparql");

    let mut mock_watcher = MockFileWatcher::new();
    let mut mock_graph = MockDependencyGraph::new();
    let mock_regen = MockRegenerationService::new();

    mock_graph
        .expect_is_query_file()
        .with(eq(query_file.clone()))
        .times(1)
        .returning(|_| true);

    mock_graph
        .expect_get_dependents()
        .with(eq(query_file.clone()))
        .times(1)
        .returning(|_| vec![PathBuf::from("templates/report.md")]);

    mock_watcher.expect_watch().times(1).returning(|| Ok(()));

    // ACT: Start watching and trigger query change
    unimplemented!("Query file watching not yet implemented");

    // ASSERT: Verify affected templates identified
}

// =============================================================================
// TEST 4: Trigger only affected templates
// =============================================================================

/// # Phase 2: Selective Regeneration Implementation
///
/// This test verifies that only affected templates are regenerated when dependencies change.
#[tokio::test]
#[ignore = "Phase 2: Selective regeneration not yet implemented"]
async fn test_watch_triggers_affected_templates_only() {
    // ARRANGE: Multiple templates, only some depend on changed RDF
    let fixture = WatchTestFixture::new();
    let rdf_file = fixture.create_rdf_file("data.ttl");
    let _template1 = fixture.create_template_file("dependent.md");
    let _template2 = fixture.create_template_file("independent.md");

    let mut mock_graph = MockDependencyGraph::new();
    let mut mock_regen = MockRegenerationService::new();

    // Only template1 depends on the RDF file
    mock_graph
        .expect_get_dependents()
        .with(eq(rdf_file.clone()))
        .times(1)
        .returning(|_| vec![PathBuf::from("templates/dependent.md")]);

    // Should regenerate only dependent template
    mock_regen
        .expect_regenerate_affected()
        .with(eq(rdf_file.clone()))
        .times(1)
        .returning(|_| Ok(vec![PathBuf::from("templates/dependent.md")]));

    // Should NOT regenerate independent template
    mock_regen
        .expect_regenerate_template()
        .with(eq(PathBuf::from("templates/independent.md")))
        .times(0);

    // ACT: Trigger RDF file change
    unimplemented!("Selective regeneration not yet implemented");

    // ASSERT: Verify only affected templates regenerated
}

// =============================================================================
// TEST 5: Handle rapid sequential changes (debouncing)
// =============================================================================

/// # Phase 2: Event Debouncing Implementation
///
/// This test verifies that rapid sequential file changes are debounced to avoid redundant regeneration.
#[tokio::test]
#[ignore = "Phase 2: Event debouncing not yet implemented"]
async fn test_watch_handles_rapid_sequential_changes() {
    // ARRANGE: Set up for multiple rapid changes
    let fixture = WatchTestFixture::new();
    let rdf_file = fixture.create_rdf_file("data.ttl");

    let mut mock_watcher = MockFileWatcher::new();
    let mut mock_regen = MockRegenerationService::new();

    // Set short debounce period for testing
    mock_watcher
        .expect_set_debounce()
        .with(eq(Duration::from_millis(100)))
        .times(1)
        .returning(|_| ());

    // Should regenerate only ONCE despite multiple changes
    let regen_count = Arc::new(Mutex::new(0));
    let regen_count_clone = regen_count.clone();

    mock_regen
        .expect_regenerate_affected()
        .times(1) // Only once after debounce
        .returning(move |_| {
            *regen_count_clone.lock().unwrap() += 1;
            Ok(vec![])
        });

    // ACT: Trigger multiple rapid changes
    // Change 1: t=0ms
    // Change 2: t=50ms
    // Change 3: t=80ms
    // Debounce completes: t=180ms
    // Should regenerate once at t=180ms

    unimplemented!("Debouncing not yet implemented");

    // ASSERT: Verify regeneration happened exactly once
    // assert_eq!(*regen_count.lock().unwrap(), 1, "Should regenerate exactly once after debounce");
}

// =============================================================================
// TEST 6: Respect debounce period
// =============================================================================

#[tokio::test]
#[ignore = "Phase 2: Feature not yet implemented"]
async fn test_watch_respects_debounce_period() {
    // ARRANGE: Configure specific debounce period
    let fixture = WatchTestFixture::new();
    let _rdf_file = fixture.create_rdf_file("data.ttl");

    let mut mock_watcher = MockFileWatcher::new();
    let debounce_duration = Duration::from_millis(500);

    mock_watcher
        .expect_set_debounce()
        .with(eq(debounce_duration))
        .times(1)
        .returning(|_| ());

    mock_watcher.expect_watch().times(1).returning(|| Ok(()));

    // ACT: Configure and start watcher
    unimplemented!("Debounce configuration not yet implemented");

    // ASSERT: Verify debounce was set correctly
}

// =============================================================================
// TEST 7: Handle file deletion
// =============================================================================

#[tokio::test]
#[ignore = "Phase 2: Feature not yet implemented"]
async fn test_watch_handles_file_deletion() {
    // ARRANGE: Set up for file deletion event
    let fixture = WatchTestFixture::new();
    let template_file = fixture.create_template_file("to-delete.md");

    let mut mock_watcher = MockFileWatcher::new();
    let mut mock_graph = MockDependencyGraph::new();

    let deletion_handled = Arc::new(Mutex::new(false));
    let deletion_handled_clone = deletion_handled.clone();

    mock_watcher
        .expect_on_change()
        .times(1)
        .returning(move |callback| {
            // Simulate deletion event
            callback(WatchEvent::Deleted(PathBuf::from("templates/to-delete.md")));
            *deletion_handled_clone.lock().unwrap() = true;
        });

    // On deletion, should update dependency graph
    mock_graph
        .expect_build_graph()
        .times(1)
        .returning(|_| Ok(()));

    mock_watcher.expect_watch().times(1).returning(|| Ok(()));

    // ACT: Start watching and trigger deletion
    unimplemented!("File deletion handling not yet implemented");

    // ASSERT: Verify deletion was handled
    // assert!(*deletion_handled.lock().unwrap(), "Deletion event should be handled");
}

// =============================================================================
// TEST 8: Handle new file creation
// =============================================================================

#[tokio::test]
#[ignore = "Phase 2: Feature not yet implemented"]
async fn test_watch_handles_new_file_creation() {
    // ARRANGE: Set up for file creation event
    let fixture = WatchTestFixture::new();

    let mut mock_watcher = MockFileWatcher::new();
    let mut mock_graph = MockDependencyGraph::new();
    let mut mock_regen = MockRegenerationService::new();

    let new_file = PathBuf::from("templates/new.md");

    mock_watcher
        .expect_on_change()
        .times(1)
        .returning(move |callback| {
            callback(WatchEvent::Created(new_file.clone()));
        });

    // Should rebuild dependency graph when new file created
    mock_graph
        .expect_build_graph()
        .times(1)
        .returning(|_| Ok(()));

    mock_graph
        .expect_is_template_file()
        .with(eq(new_file.clone()))
        .times(1)
        .returning(|_| true);

    // New template should be regenerated
    mock_regen
        .expect_regenerate_template()
        .with(eq(new_file.clone()))
        .times(1)
        .returning(|_| Ok(()));

    mock_watcher.expect_watch().times(1).returning(|| Ok(()));

    // ACT: Start watching and trigger file creation
    unimplemented!("File creation handling not yet implemented");

    // ASSERT: Verify new file was processed
}

// =============================================================================
// TEST 9: Handle directory creation
// =============================================================================

#[tokio::test]
#[ignore = "Phase 2: Feature not yet implemented"]
async fn test_watch_handles_directory_creation() {
    // ARRANGE: Set up for directory creation event
    let fixture = WatchTestFixture::new();

    let mut mock_watcher = MockFileWatcher::new();
    let mut mock_graph = MockDependencyGraph::new();

    let new_dir = fixture.project_root.join("templates/components");

    mock_watcher
        .expect_on_change()
        .times(1)
        .returning(move |callback| {
            callback(WatchEvent::Created(new_dir.clone()));
        });

    // Should watch the new directory
    mock_graph
        .expect_build_graph()
        .times(1)
        .returning(|_| Ok(()));

    mock_watcher.expect_watch().times(1).returning(|| Ok(()));

    // ACT: Start watching and trigger directory creation
    unimplemented!("Directory watching not yet implemented");

    // ASSERT: Verify new directory is being watched
}

// =============================================================================
// TEST 10: Ignore generated directory
// =============================================================================

#[tokio::test]
#[ignore = "Phase 2: Feature not yet implemented"]
async fn test_watch_ignores_generated_directory() {
    // ARRANGE: Set up event filter for generated directory
    let fixture = WatchTestFixture::new();
    let generated_file = fixture.project_root.join("generated/output.md");

    let mut mock_filter = MockEventFilter::new();
    let mut mock_regen = MockRegenerationService::new();

    // Filter should identify generated directory
    mock_filter
        .expect_is_generated_directory()
        .with(eq(generated_file.clone()))
        .times(1)
        .returning(|_| true);

    mock_filter
        .expect_should_ignore()
        .with(eq(generated_file.clone()))
        .times(1)
        .returning(|_| true);

    // Regeneration should NOT be triggered for generated files
    mock_regen.expect_regenerate_template().times(0);

    mock_regen.expect_regenerate_affected().times(0);

    // ACT: Trigger change in generated directory
    unimplemented!("Event filtering not yet implemented");

    // ASSERT: Verify generated files were ignored
}

// =============================================================================
// Integration test placeholder (will be moved to integration tests later)
// =============================================================================

#[tokio::test]
#[ignore = "Integration test - run separately"]
#[ignore = "Phase 2: Feature not yet implemented"]
async fn integration_test_watch_full_workflow() {
    // ARRANGE: Real file system, no mocks
    let fixture = WatchTestFixture::new();

    // Create real files
    let rdf_file = fixture.create_rdf_file("data.ttl");
    let template_file = fixture.create_template_file("output.md");

    // ACT: Start real watcher, modify RDF, wait for regeneration
    unimplemented!("Full watch integration not yet implemented");

    // ASSERT: Verify template was regenerated with new RDF data
    // assert!(fixture.project_root.join("generated/output.md").exists());
}

// =============================================================================
// Helper tests for internal components
// =============================================================================

#[test]
#[ignore = "Phase 2: Feature not yet implemented"]
fn test_event_filter_patterns() {
    // ARRANGE: Create event filter with patterns
    let mut filter = MockEventFilter::new();

    filter
        .expect_add_ignore_pattern()
        .with(eq("**/generated/**"))
        .times(1)
        .returning(|_| ());

    filter
        .expect_add_ignore_pattern()
        .with(eq("**/.git/**"))
        .times(1)
        .returning(|_| ());

    filter.expect_should_ignore().times(2).returning(|_| true);

    // ACT: Add ignore patterns
    unimplemented!("EventFilter not yet implemented");

    // ASSERT: Verify patterns work correctly
    // assert!(filter.should_ignore("generated/output.md"));
    // assert!(filter.should_ignore(".git/config"));
}

#[test]
#[ignore = "Phase 2: Feature not yet implemented"]
fn test_dependency_graph_build() {
    // ARRANGE: Create dependency graph
    let fixture = WatchTestFixture::new();
    let mut mock_graph = MockDependencyGraph::new();

    mock_graph
        .expect_build_graph()
        .with(eq(fixture.project_root.clone()))
        .times(1)
        .returning(|_| Ok(()));

    // ACT: Build dependency graph
    unimplemented!("DependencyGraph::build_graph not yet implemented");

    // ASSERT: Verify graph was built
}

// =============================================================================
// Performance test placeholder
// =============================================================================

#[tokio::test]
#[ignore = "Performance test - run separately"]
#[ignore = "Phase 2: Feature not yet implemented"]
async fn perf_test_watch_handles_high_frequency_changes() {
    // ARRANGE: Many files changing rapidly
    let fixture = WatchTestFixture::new();

    // Create 100 templates
    for i in 0..100 {
        fixture.create_template_file(&format!("template_{}.md", i));
    }

    // ACT: Trigger 1000 changes in 1 second
    unimplemented!("Performance testing not yet implemented");

    // ASSERT: Verify all changes handled without crashes
    // Verify memory usage stays reasonable
    // Verify CPU usage stays reasonable
}
