use std::{collections::HashMap, sync::Arc};
use uuid::Uuid;
use readur::{
    AppState,
    models::{CreateWebDAVDirectory, FileIngestionInfo, User, AuthProvider},
    services::webdav::{
        SmartSyncService, SmartSyncStrategy, SmartSyncDecision, 
        WebDAVService, WebDAVConfig
    },
    test_utils::{TestContext, TestAuthHelper},
};

// Note: Mocking is complex due to WebDAV service dependencies
// These tests focus on the logic we can test without full WebDAV integration

/// Helper function to create test setup with database
async fn create_test_state() -> (TestContext, Arc<AppState>, Uuid) {
    // Create a fresh test context for each test, following the pattern used in all other tests
    let test_context = TestContext::new().await;
    
    let auth_helper = TestAuthHelper::new(test_context.app().clone());
    let test_user = auth_helper.create_test_user().await;

    let state = test_context.state().clone();
    let user_id = test_user.user_response.id;
    
    (test_context, state, user_id)
}

/// Helper function to create directory info for testing
fn create_directory_info(path: &str, etag: &str) -> FileIngestionInfo {
    FileIngestionInfo {
        relative_path: path.to_string(),
        full_path: path.to_string(),
        #[allow(deprecated)]
        path: path.to_string(),
        name: path.split('/').last().unwrap_or("").to_string(),
        size: 0,
        mime_type: "".to_string(),
        last_modified: Some(chrono::Utc::now()),
        etag: etag.to_string(),
        is_directory: true,
        created_at: Some(chrono::Utc::now()),
        permissions: Some(0),
        owner: None,
        group: None,
        metadata: None,
    }
}

#[tokio::test]
async fn test_evaluate_sync_need_first_time_no_known_directories() {
    // Unit Test: First-time sync evaluation with no existing directory ETags
    // Expected: Should return RequiresSync(FullDeepScan)
    
    let (_test_context, state, user_id) = create_test_state().await;
    let smart_sync_service = SmartSyncService::new(state.clone());
    
    // Test evaluation - should detect no known directories and require deep scan
    let webdav_service = create_real_webdav_service();
    let decision = smart_sync_service.evaluate_sync_need(user_id, &webdav_service, "/Documents", None).await;
    
    match decision {
        Ok(SmartSyncDecision::RequiresSync(SmartSyncStrategy::FullDeepScan)) => {
            println!("✅ First-time sync correctly requires FullDeepScan");
        }
        Ok(other) => panic!("Expected FullDeepScan for first-time sync, got: {:?}", other),
        Err(_) => {
            println!("✅ First-time sync evaluation failed as expected in test environment");
        }
    }
}

#[tokio::test]
async fn test_evaluate_sync_need_no_changes_skip_sync() {
    // Unit Test: Smart sync evaluation with no directory changes
    // Expected: Should return SkipSync
    
    let (_test_context, state, user_id) = create_test_state().await;
    let smart_sync_service = SmartSyncService::new(state.clone());
    
    // Pre-populate database with known directory ETags
    let known_directories = vec![
        ("/Documents", "root-etag-unchanged"),
        ("/Documents/Projects", "projects-etag-unchanged"),
        ("/Documents/Archive", "archive-etag-unchanged"),
    ];
    
    for (path, etag) in &known_directories {
        let dir = CreateWebDAVDirectory {
            user_id,
            directory_path: path.to_string(),
            directory_etag: etag.to_string(),
            file_count: 5,
            total_size_bytes: 1024000,
        };
        
        state.db.create_or_update_webdav_directory(&dir).await
            .expect("Failed to create directory tracking");
    }
    
    // For this test, we need to mock the WebDAV service to return unchanged ETags
    // This would require a more sophisticated mock that can be injected into SmartSyncService
    
    // Verify known directories were created
    let stored_dirs = state.db.list_webdav_directories(user_id).await
        .expect("Failed to list directories");
    assert_eq!(stored_dirs.len(), 3, "Should have 3 known directories");
    
    println!("✅ Test setup complete: Known directories in database for no-change scenario");
    // TODO: Complete this test with mocked WebDAV service returning same ETags
}

#[tokio::test]
async fn test_strategy_selection_few_changes_targeted_scan() {
    // Unit Test: Strategy selection logic for small number of changes
    // Expected: Should use TargetedScan for few changed directories
    
    let change_ratio = 2.0 / 10.0; // 2 changed out of 10 total = 20%
    let new_dirs_count = 1;
    
    // This logic mirrors what's in SmartSyncService::evaluate_sync_need
    let should_use_targeted = change_ratio <= 0.3 && new_dirs_count <= 5;
    
    assert!(should_use_targeted, "Should use targeted scan for small changes");
    println!("✅ Strategy selection: Small changes correctly trigger targeted scan");
}

#[tokio::test]
async fn test_strategy_selection_many_changes_full_scan() {
    // Unit Test: Strategy selection logic for many changes
    // Expected: Should fall back to FullDeepScan for efficiency
    
    let scenarios = vec![
        (4.0 / 10.0, 2), // 40% change ratio > 30% threshold
        (2.0 / 10.0, 6), // Low ratio but 6 new dirs > 5 threshold
        (5.0 / 10.0, 8), // Both thresholds exceeded
    ];
    
    for (change_ratio, new_dirs_count) in scenarios {
        let should_use_full_scan = change_ratio > 0.3 || new_dirs_count > 5;
        assert!(should_use_full_scan, 
                "Ratio {:.1}% with {} new dirs should trigger full scan", 
                change_ratio * 100.0, new_dirs_count);
    }
    
    println!("✅ Strategy selection: Many changes correctly trigger full deep scan");
}

#[tokio::test]
async fn test_directory_etag_comparison_logic() {
    // Unit Test: Directory ETag comparison and change detection
    // Expected: Should correctly identify changed, new, and unchanged directories
    
    let (_test_context, state, user_id) = create_test_state().await;
    
    // Setup known directories in database
    let known_dirs = vec![
        ("/Documents", "root-etag-old"),
        ("/Documents/Projects", "projects-etag-stable"), 
        ("/Documents/Archive", "archive-etag-old"),
        ("/Documents/ToBeDeleted", "deleted-etag"), // This won't appear in "current"
    ];
    
    for (path, etag) in &known_dirs {
        let dir = CreateWebDAVDirectory {
            user_id,
            directory_path: path.to_string(),
            directory_etag: etag.to_string(),
            file_count: 3,
            total_size_bytes: 512000,
        };
        
        state.db.create_or_update_webdav_directory(&dir).await
            .expect("Failed to create known directory");
    }
    
    // Simulate current directories from WebDAV (what we'd get from discovery)
    let current_dirs = vec![
        create_directory_info("/Documents", "root-etag-new"), // Changed
        create_directory_info("/Documents/Projects", "projects-etag-stable"), // Unchanged
        create_directory_info("/Documents/Archive", "archive-etag-new"), // Changed  
        create_directory_info("/Documents/NewFolder", "new-folder-etag"), // New
    ];
    
    // Get known directories from database
    let known_map: HashMap<String, String> = state.db.list_webdav_directories(user_id).await
        .expect("Failed to get known directories")
        .into_iter()
        .filter(|dir| dir.directory_path.starts_with("/Documents"))
        .map(|dir| (dir.directory_path, dir.directory_etag))
        .collect();
    
    // Perform comparison logic (mirrors SmartSyncService logic)
    let mut changed_directories = Vec::new();
    let mut new_directories = Vec::new();
    let mut unchanged_directories = Vec::new();
    
    for current_dir in &current_dirs {
        match known_map.get(&current_dir.relative_path) {
            Some(known_etag) => {
                if known_etag != &current_dir.etag {
                    changed_directories.push(current_dir.relative_path.clone());
                } else {
                    unchanged_directories.push(current_dir.relative_path.clone());
                }
            }
            None => {
                new_directories.push(current_dir.relative_path.clone());
            }
        }
    }
    
    // Verify comparison results
    assert_eq!(changed_directories.len(), 2, "Should detect 2 changed directories");
    assert!(changed_directories.contains(&"/Documents".to_string()));
    assert!(changed_directories.contains(&"/Documents/Archive".to_string()));
    
    assert_eq!(new_directories.len(), 1, "Should detect 1 new directory");
    assert!(new_directories.contains(&"/Documents/NewFolder".to_string()));
    
    assert_eq!(unchanged_directories.len(), 1, "Should detect 1 unchanged directory");
    assert!(unchanged_directories.contains(&"/Documents/Projects".to_string()));
    
    // Note: Deleted directories (/Documents/ToBeDeleted) would need separate logic
    // to detect directories that exist in DB but not in current WebDAV response
    
    println!("✅ Directory ETag comparison correctly identifies changes, new, and unchanged directories");
}

#[tokio::test]
async fn test_bulk_directory_fetching_performance() {
    // Unit Test: Bulk directory ETag fetching vs individual queries
    // Expected: Should fetch all relevant directories in single database query
    
    let (_test_context, state, user_id) = create_test_state().await;
    
    // Create many directories across different folder hierarchies
    let directories = (0..50).map(|i| {
        let path = if i < 20 {
            format!("/Documents/Folder{}", i)
        } else if i < 35 {
            format!("/Photos/Album{}", i - 20)
        } else {
            format!("/Documents/Subfolder/Deep{}", i - 35)
        };
        
        (path, format!("etag-{}", i))
    }).collect::<Vec<_>>();
    
    // Insert all directories
    for (path, etag) in &directories {
        let dir = CreateWebDAVDirectory {
            user_id,
            directory_path: path.clone(),
            directory_etag: etag.clone(),
            file_count: 1,
            total_size_bytes: 100000,
        };
        
        state.db.create_or_update_webdav_directory(&dir).await
            .expect("Failed to create directory");
    }
    
    // Test bulk fetch for specific folder path
    let start = std::time::Instant::now();
    let documents_dirs = state.db.list_webdav_directories(user_id).await
        .expect("Failed to fetch directories");
    let fetch_duration = start.elapsed();
    
    // Filter to Documents folder (simulates SmartSyncService filtering)
    let filtered_dirs: Vec<_> = documents_dirs
        .into_iter()
        .filter(|dir| dir.directory_path.starts_with("/Documents"))
        .collect();
    
    // Verify bulk fetch results
    assert!(filtered_dirs.len() >= 35, "Should fetch Documents directories"); // 20 + 15 deep
    assert!(fetch_duration.as_millis() < 100, "Bulk fetch should be fast (< 100ms)");
    
    println!("✅ Bulk directory fetching: {} directories in {:?}", 
             filtered_dirs.len(), fetch_duration);
}

#[tokio::test] 
async fn test_smart_sync_error_handling() {
    // Unit Test: Error handling and fallback behavior
    // Expected: Should handle various error conditions gracefully
    
    let (_test_context, state, user_id) = create_test_state().await;
    let smart_sync_service = SmartSyncService::new(state.clone());
    
    // Test database error handling (simulate by using invalid user ID)
    let invalid_user_id = Uuid::new_v4();
    
    // This should not panic, but handle the error gracefully
    let webdav_service = create_real_webdav_service();
    let decision = smart_sync_service.evaluate_sync_need(invalid_user_id, &webdav_service, "/Documents", None).await;
    
    match decision {
        Ok(SmartSyncDecision::RequiresSync(SmartSyncStrategy::FullDeepScan)) => {
            println!("✅ Database error handled - falls back to full deep scan");
        }
        Err(e) => {
            println!("✅ Database error properly returned: {}", e);
        }
        other => panic!("Unexpected result for invalid user: {:?}", other),
    }
    
    println!("✅ Error handling test completed");
}

/// Helper function to create a real WebDAV service for tests that need it
fn create_real_webdav_service() -> WebDAVService {
    let config = WebDAVConfig {
        server_url: "https://test.example.com".to_string(),
        username: "test".to_string(),
        password: "test".to_string(),
        watch_folders: vec!["/Documents".to_string()],
        file_extensions: vec!["pdf".to_string(), "txt".to_string()],
        timeout_seconds: 30,
        server_type: Some("generic".to_string()),
    };
    
    WebDAVService::new(config).expect("Failed to create WebDAV service")
}

// Additional unit test stubs for specific functionality
#[tokio::test]
async fn test_targeted_scan_directory_selection() {
    // Unit Test: Targeted scan should only process changed directories
    println!("📝 Unit test stub: Targeted scan directory selection logic");
    // TODO: Test that TargetedScan only processes specific changed directories
}

#[tokio::test]
async fn test_directory_etag_update_after_scan() {
    // Unit Test: Directory ETags should be updated after successful scan
    println!("📝 Unit test stub: Directory ETag update after scan completion");
    // TODO: Test that perform_smart_sync updates directory ETags in database
}

#[tokio::test]
async fn test_deep_scan_vs_targeted_scan_coverage() {
    // Unit Test: Deep scan should process all directories, targeted scan only specific ones
    println!("📝 Unit test stub: Deep vs targeted scan coverage comparison");
    // TODO: Test that FullDeepScan processes entire hierarchy, TargetedScan processes subset
}

#[tokio::test]
async fn test_smart_sync_decision_caching() {
    // Unit Test: Smart sync decisions should be efficient for repeated calls
    println!("📝 Unit test stub: Smart sync decision efficiency");
    // TODO: Test performance of repeated smart sync evaluations
}