//! Comprehensive migration tests for storage backend transitions
//!
//! This module tests data migration between all supported storage backends,
//! ensuring data integrity, rollback functionality, and performance characteristics.

use std::sync::Arc;
use tempfile::TempDir;
use tokio_test;

// Import test helpers and orchestrator types
mod helpers;
use helpers::{TestEnvironment, TestDataGenerator, StorageAssertions};

use orchestrator::{TaskStatus, WorkflowTask};
use orchestrator::storage::{StorageConfig, create_storage};
use orchestrator::migration::{
    StorageMigrator, MigrationConfig, MigrationOptions, MigrationStatus,
    RollbackManager, RollbackConfig, RollbackStrategy, RollbackStatus
};

/// Test basic migration between filesystem and SurrealDB embedded
#[cfg(feature = "surrealdb")]
#[tokio::test]
async fn test_filesystem_to_embedded_migration() {
    let mut env = TestEnvironment::new();
    let gen = TestDataGenerator::new();

    let source_config = env.filesystem_config().unwrap();
    let target_config = env.surrealdb_embedded_config().unwrap();

    // Setup source data
    let source_storage = create_storage(source_config.clone()).await.unwrap();
    source_storage.init().await.unwrap();

    let test_tasks = gen.workflow_tasks_batch(10);
    for task in &test_tasks {
        source_storage.enqueue(task.clone(), 1).await.unwrap();
    }

    // Add some audit entries and metrics
    let audit_entry = gen.audit_entry(test_tasks[0].id.clone());
    source_storage.record_audit_entry(audit_entry).await.unwrap();

    let metric = gen.metric("test_metric", 42.0);
    source_storage.record_metric(metric).await.unwrap();

    // Configure migration
    let migration_config = MigrationConfig {
        source_config,
        target_config,
        options: MigrationOptions {
            dry_run: false,
            verify_integrity: true,
            create_backup: true,
            ..Default::default()
        },
    };

    // Execute migration
    let migrator = StorageMigrator::new(migration_config);
    let report = migrator.execute().await.unwrap();

    // Verify migration success
    assert_eq!(report.status, MigrationStatus::Completed);
    assert_eq!(report.statistics.tasks_migrated, 10);
    assert_eq!(report.statistics.tasks_failed, 0);
    assert_eq!(report.errors.len(), 0);

    // Verify data in target storage
    let target_storage = create_storage(report.target_backend.parse().unwrap()).await.unwrap();
    StorageAssertions::assert_task_count(&target_storage, 10).await.unwrap();
}

/// Test migration with progress callback
#[tokio::test]
async fn test_migration_with_progress_tracking() {
    let mut env = TestEnvironment::new();
    let gen = TestDataGenerator::new();

    let source_config = env.filesystem_config().unwrap();
    let target_config = env.filesystem_config().unwrap(); // Different directory

    // Setup source data
    let source_storage = create_storage(source_config.clone()).await.unwrap();
    source_storage.init().await.unwrap();

    let test_tasks = gen.workflow_tasks_batch(5);
    for task in &test_tasks {
        source_storage.enqueue(task.clone(), 1).await.unwrap();
    }

    // Track progress updates
    let progress_updates = Arc::new(std::sync::Mutex::new(Vec::new()));
    let progress_updates_clone = progress_updates.clone();

    let progress_callback = Arc::new(move |progress: &orchestrator::migration::MigrationProgress| {
        progress_updates_clone.lock().unwrap().push((
            progress.phase.clone(),
            progress.percentage,
            progress.message.clone(),
        ));
    });

    // Configure migration
    let migration_config = MigrationConfig {
        source_config,
        target_config,
        options: MigrationOptions {
            dry_run: false,
            batch_size: 2,
            ..Default::default()
        },
    };

    // Execute migration with progress tracking
    let migrator = StorageMigrator::new(migration_config)
        .with_progress_callback(progress_callback);

    let report = migrator.execute().await.unwrap();

    // Verify migration success
    assert_eq!(report.status, MigrationStatus::Completed);
    assert_eq!(report.statistics.tasks_migrated, 5);

    // Verify progress was tracked
    let updates = progress_updates.lock().unwrap();
    assert!(!updates.is_empty());

    // Check that we received updates for all phases
    let phases: Vec<String> = updates.iter().map(|(phase, _, _)| phase.clone()).collect();
    assert!(phases.contains(&"validation".to_string()));
    assert!(phases.contains(&"connection".to_string()));
    assert!(phases.contains(&"discovery".to_string()));
    assert!(phases.contains(&"migration".to_string()));
}

/// Test migration with filtering options
#[tokio::test]
async fn test_migration_with_filtering() {
    let mut env = TestEnvironment::new();
    let gen = TestDataGenerator::new();

    let source_config = env.filesystem_config().unwrap();
    let target_config = env.filesystem_config().unwrap();

    // Setup source data with different statuses
    let source_storage = create_storage(source_config.clone()).await.unwrap();
    source_storage.init().await.unwrap();

    let pending_tasks = (0..3).map(|_| gen.workflow_task_with_status(TaskStatus::Pending)).collect::<Vec<_>>();
    let completed_tasks = (0..2).map(|_| gen.workflow_task_with_status(TaskStatus::Completed)).collect::<Vec<_>>();
    let failed_tasks = (0..1).map(|_| gen.workflow_task_with_status(TaskStatus::Failed)).collect::<Vec<_>>();

    for task in &pending_tasks {
        source_storage.enqueue(task.clone(), 1).await.unwrap();
    }
    for task in &completed_tasks {
        source_storage.enqueue(task.clone(), 1).await.unwrap();
    }
    for task in &failed_tasks {
        source_storage.enqueue(task.clone(), 1).await.unwrap();
    }

    // Configure migration to only migrate pending and completed tasks
    let migration_config = MigrationConfig {
        source_config,
        target_config,
        options: MigrationOptions {
            dry_run: false,
            status_filter: Some(vec![TaskStatus::Pending, TaskStatus::Completed]),
            verify_integrity: false, // Skip integrity check for filtered migration
            ..Default::default()
        },
    };

    // Execute migration
    let migrator = StorageMigrator::new(migration_config);
    let report = migrator.execute().await.unwrap();

    // Verify migration success
    assert_eq!(report.status, MigrationStatus::Completed);
    assert_eq!(report.statistics.tasks_migrated, 5); // 3 pending + 2 completed
    assert_eq!(report.statistics.tasks_failed, 0);

    // Verify target storage contains only filtered tasks
    let target_storage = create_storage(report.target_backend.parse().unwrap()).await.unwrap();
    StorageAssertions::assert_task_count(&target_storage, 5).await.unwrap();

    let failed_tasks_in_target = target_storage.list_tasks(Some(TaskStatus::Failed)).await.unwrap();
    assert_eq!(failed_tasks_in_target.len(), 0);
}

/// Test dry run migration
#[tokio::test]
async fn test_dry_run_migration() {
    let mut env = TestEnvironment::new();
    let gen = TestDataGenerator::new();

    let source_config = env.filesystem_config().unwrap();
    let target_config = env.filesystem_config().unwrap();

    // Setup source data
    let source_storage = create_storage(source_config.clone()).await.unwrap();
    source_storage.init().await.unwrap();

    let test_tasks = gen.workflow_tasks_batch(5);
    for task in &test_tasks {
        source_storage.enqueue(task.clone(), 1).await.unwrap();
    }

    // Configure dry run migration
    let migration_config = MigrationConfig {
        source_config,
        target_config: target_config.clone(),
        options: MigrationOptions {
            dry_run: true,
            ..Default::default()
        },
    };

    // Execute dry run
    let migrator = StorageMigrator::new(migration_config);
    let report = migrator.execute().await.unwrap();

    // Verify dry run completed successfully
    assert_eq!(report.status, MigrationStatus::Completed);
    assert_eq!(report.statistics.tasks_migrated, 5);

    // Verify target storage is empty (no actual migration occurred)
    let target_storage = create_storage(target_config).await.unwrap();
    target_storage.init().await.unwrap();
    StorageAssertions::assert_task_count(&target_storage, 0).await.unwrap();
}

/// Test migration failure and rollback
#[tokio::test]
async fn test_migration_failure_and_rollback() {
    let mut env = TestEnvironment::new();
    let gen = TestDataGenerator::new();

    let source_config = env.filesystem_config().unwrap();

    // Create an invalid target config to force migration failure
    let mut target_config = env.filesystem_config().unwrap();
    target_config.data_dir = "/invalid/path/that/does/not/exist".to_string();

    // Setup source data
    let source_storage = create_storage(source_config.clone()).await.unwrap();
    source_storage.init().await.unwrap();

    let test_tasks = gen.workflow_tasks_batch(3);
    for task in &test_tasks {
        source_storage.enqueue(task.clone(), 1).await.unwrap();
    }

    // Configure migration with backup for rollback
    let migration_config = MigrationConfig {
        source_config,
        target_config,
        options: MigrationOptions {
            dry_run: false,
            create_backup: true,
            ..Default::default()
        },
    };

    // Execute migration (should fail)
    let migrator = StorageMigrator::new(migration_config);
    let report = migrator.execute().await.unwrap();

    // Verify migration failed
    assert_eq!(report.status, MigrationStatus::Failed);
    assert!(!report.errors.is_empty());

    // Check if automatic rollback was attempted
    assert!(!report.warnings.is_empty());
    let rollback_warning = report.warnings.iter()
        .find(|w| w.contains("Automatic rollback executed"));
    assert!(rollback_warning.is_some());
}

/// Test manual rollback process
#[tokio::test]
async fn test_manual_rollback_process() {
    let rollback_config = RollbackConfig {
        backup_path: "/tmp/test_backup.json".to_string(),
        migration_id: "test_migration_123".to_string(),
        rollback_strategy: RollbackStrategy::Manual,
    };

    let rollback_manager = RollbackManager::new(rollback_config);

    // Create a mock target storage for rollback
    let mut env = TestEnvironment::new();
    let target_config = env.filesystem_config().unwrap();
    let target_storage = create_storage(target_config).await.unwrap();
    target_storage.init().await.unwrap();

    // Execute manual rollback
    let rollback_report = rollback_manager.execute_rollback(&target_storage).await.unwrap();

    // Verify rollback completed (manual strategy just generates instructions)
    assert_eq!(rollback_report.status, RollbackStatus::Completed);
    assert!(!rollback_report.actions_performed.is_empty());

    // Check that instructions were generated
    let instruction_action = rollback_report.actions_performed.iter()
        .find(|a| a.action.contains("manual_instructions"));
    assert!(instruction_action.is_some());
}

/// Test migration between different backend combinations
#[cfg(feature = "surrealdb")]
#[tokio::test]
async fn test_all_backend_combinations() {
    let mut env = TestEnvironment::new();
    let gen = TestDataGenerator::new();

    let configs = env.all_storage_configs();

    // Test migration between each pair of backends
    for (i, source_config) in configs.iter().enumerate() {
        for (j, target_config) in configs.iter().enumerate() {
            if i == j {
                continue; // Skip same backend migrations
            }

            println!("Testing migration from {} to {}",
                     source_config.storage_type, target_config.storage_type);

            // Setup source data
            let source_storage = create_storage(source_config.clone()).await.unwrap();
            source_storage.init().await.unwrap();

            let test_tasks = gen.workflow_tasks_batch(3);
            for task in &test_tasks {
                source_storage.enqueue(task.clone(), 1).await.unwrap();
            }

            // Configure migration
            let migration_config = MigrationConfig {
                source_config: source_config.clone(),
                target_config: target_config.clone(),
                options: MigrationOptions {
                    dry_run: false,
                    verify_integrity: true,
                    create_backup: false, // Skip backup for test speed
                    ..Default::default()
                },
            };

            // Execute migration
            let migrator = StorageMigrator::new(migration_config);
            let report = migrator.execute().await.unwrap();

            // Verify migration success
            assert_eq!(report.status, MigrationStatus::Completed);
            assert_eq!(report.statistics.tasks_migrated, 3);
            assert_eq!(report.statistics.tasks_failed, 0);

            println!("✓ Migration from {} to {} successful",
                     source_config.storage_type, target_config.storage_type);
        }
    }
}

/// Test large dataset migration performance
#[tokio::test]
async fn test_large_dataset_migration_performance() {
    let mut env = TestEnvironment::new();
    let gen = TestDataGenerator::new();

    let source_config = env.filesystem_config().unwrap();
    let target_config = env.filesystem_config().unwrap();

    // Setup large dataset
    let source_storage = create_storage(source_config.clone()).await.unwrap();
    source_storage.init().await.unwrap();

    let task_count = 1000;
    println!("Setting up {} tasks for migration...", task_count);

    let batch_tasks: Vec<(WorkflowTask, u8)> = (0..task_count)
        .map(|i| (gen.workflow_task(), (i % 10 + 1) as u8))
        .collect();

    source_storage.enqueue_batch(batch_tasks).await.unwrap();

    // Configure migration with optimized batch size
    let migration_config = MigrationConfig {
        source_config,
        target_config,
        options: MigrationOptions {
            dry_run: false,
            batch_size: 100,
            verify_integrity: false, // Skip for performance
            create_backup: false,
            ..Default::default()
        },
    };

    // Execute migration with timing
    let start = std::time::Instant::now();
    let migrator = StorageMigrator::new(migration_config);
    let report = migrator.execute().await.unwrap();
    let duration = start.elapsed();

    // Verify migration success
    assert_eq!(report.status, MigrationStatus::Completed);
    assert_eq!(report.statistics.tasks_migrated, task_count);

    println!("Migration of {} tasks completed in {:?}", task_count, duration);
    println!("Throughput: {:.2} tasks/second", report.statistics.throughput_tasks_per_second);

    // Performance should be reasonable (adjust based on requirements)
    assert!(duration.as_secs() < 30, "Migration took too long: {:?}", duration);
    assert!(report.statistics.throughput_tasks_per_second > 10.0, "Throughput too low");
}

/// Test migration with data integrity verification
#[tokio::test]
async fn test_migration_data_integrity() {
    let mut env = TestEnvironment::new();
    let gen = TestDataGenerator::new();

    let source_config = env.filesystem_config().unwrap();
    let target_config = env.filesystem_config().unwrap();

    // Setup source data with complex tasks
    let source_storage = create_storage(source_config.clone()).await.unwrap();
    source_storage.init().await.unwrap();

    let mut complex_task = gen.workflow_task();
    complex_task.args = vec!["arg1".to_string(), "arg2".to_string(), "arg3".to_string()];
    complex_task.dependencies = vec!["dep1".to_string(), "dep2".to_string()];
    complex_task.status = TaskStatus::Running;
    complex_task.started_at = Some(chrono::Utc::now());
    complex_task.output = Some("Complex output data".to_string());

    source_storage.enqueue(complex_task.clone(), 5).await.unwrap();

    // Configure migration with integrity verification
    let migration_config = MigrationConfig {
        source_config,
        target_config: target_config.clone(),
        options: MigrationOptions {
            dry_run: false,
            verify_integrity: true,
            ..Default::default()
        },
    };

    // Execute migration
    let migrator = StorageMigrator::new(migration_config);
    let report = migrator.execute().await.unwrap();

    // Verify migration success with integrity check
    assert_eq!(report.status, MigrationStatus::Completed);
    assert_eq!(report.statistics.tasks_migrated, 1);
    assert_eq!(report.errors.len(), 0);

    // Verify complex data was preserved
    let target_storage = create_storage(target_config).await.unwrap();
    target_storage.init().await.unwrap();

    let migrated_task = target_storage.get_task(&complex_task.id).await.unwrap().unwrap();
    assert_eq!(migrated_task.args, complex_task.args);
    assert_eq!(migrated_task.dependencies, complex_task.dependencies);
    assert_eq!(migrated_task.status, complex_task.status);
    assert_eq!(migrated_task.output, complex_task.output);
}

/// Test migration rollback with target storage cleanup
#[tokio::test]
async fn test_rollback_with_target_cleanup() {
    let mut env = TestEnvironment::new();
    let gen = TestDataGenerator::new();

    // Create a valid target config
    let target_config = env.filesystem_config().unwrap();
    let target_storage = create_storage(target_config.clone()).await.unwrap();
    target_storage.init().await.unwrap();

    // Add some test data to target storage (simulating partial migration)
    let test_tasks = gen.workflow_tasks_batch(3);
    for task in &test_tasks {
        target_storage.enqueue(task.clone(), 1).await.unwrap();
    }

    StorageAssertions::assert_task_count(&target_storage, 3).await.unwrap();

    // Configure rollback to clear target storage
    let rollback_config = RollbackConfig {
        backup_path: "/tmp/nonexistent_backup.json".to_string(),
        migration_id: "test_migration_456".to_string(),
        rollback_strategy: RollbackStrategy::ClearTargetRestoreSource,
    };

    let rollback_manager = RollbackManager::new(rollback_config);

    // Execute rollback
    let rollback_report = rollback_manager.execute_rollback(&target_storage).await.unwrap();

    // Note: The current implementation doesn't support task deletion
    // This test verifies the rollback process recognizes the limitation
    assert_eq!(rollback_report.status, RollbackStatus::PartiallyCompleted);
    assert!(!rollback_report.errors.is_empty());

    let limitation_error = rollback_report.errors.iter()
        .find(|e| e.contains("TaskStorage trait lacks delete_task method"));
    assert!(limitation_error.is_some());
}

/// Test migration continuation after non-critical errors
#[tokio::test]
async fn test_migration_continue_on_error() {
    let mut env = TestEnvironment::new();
    let gen = TestDataGenerator::new();

    let source_config = env.filesystem_config().unwrap();
    let target_config = env.filesystem_config().unwrap();

    // Setup source data
    let source_storage = create_storage(source_config.clone()).await.unwrap();
    source_storage.init().await.unwrap();

    let test_tasks = gen.workflow_tasks_batch(5);
    for task in &test_tasks {
        source_storage.enqueue(task.clone(), 1).await.unwrap();
    }

    // Configure migration to continue on error
    let migration_config = MigrationConfig {
        source_config,
        target_config,
        options: MigrationOptions {
            dry_run: false,
            continue_on_error: true,
            max_retries: 1,
            verify_integrity: false,
            ..Default::default()
        },
    };

    // Execute migration
    let migrator = StorageMigrator::new(migration_config);
    let report = migrator.execute().await.unwrap();

    // Migration should complete despite potential errors
    assert_eq!(report.status, MigrationStatus::Completed);
    assert_eq!(report.statistics.tasks_migrated, 5);
}

/// Test migration utility functions for common scenarios
#[cfg(feature = "surrealdb")]
#[tokio::test]
async fn test_migration_utility_functions() {
    let mut env = TestEnvironment::new();

    let source_dir = env.create_temp_dir().unwrap();
    let target_dir = env.create_temp_dir().unwrap();

    // Test filesystem to embedded utility
    let migration_options = MigrationOptions {
        dry_run: true,
        ..Default::default()
    };

    let migrator = StorageMigrator::filesystem_to_embedded(
        &source_dir.to_string_lossy(),
        &target_dir.to_string_lossy(),
        Some(migration_options),
    );

    // Verify configuration was set correctly
    let report = migrator.execute().await.unwrap();
    assert_eq!(report.source_backend, "filesystem");
    assert_eq!(report.target_backend, "surrealdb-embedded");
    assert_eq!(report.status, MigrationStatus::Completed);

    // Test embedded to server utility
    let migrator = StorageMigrator::embedded_to_server(
        &target_dir.to_string_lossy(),
        "memory://test",
        "test",
        "test",
        Some(MigrationOptions {
            dry_run: true,
            ..Default::default()
        }),
    );

    let report = migrator.execute().await.unwrap();
    assert_eq!(report.source_backend, "surrealdb-embedded");
    assert_eq!(report.target_backend, "surrealdb-server");
    assert_eq!(report.status, MigrationStatus::Completed);
}