use std::collections::HashMap;
use std::sync::Arc;
use tokio::time::{sleep, Duration};
use uuid::Uuid;
use chrono::Utc;
use serde_json;

// Simplified test structures for batch workflow testing
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum TaskType {
    Server,
    Taskserv,
    Cluster,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum TaskState {
    Pending,
    Running,
    Completed,
    Failed,
}

#[derive(Debug, Clone)]
pub struct TaskDependency {
    pub task_id: Uuid,
    pub dependency_type: String,
}

#[derive(Debug, Clone)]
pub struct BatchTask {
    pub id: Uuid,
    pub name: String,
    pub task_type: TaskType,
    pub provider: String,
    pub config: serde_json::Value,
    pub dependencies: Vec<TaskDependency>,
    pub state: TaskState,
    pub created_at: chrono::DateTime<Utc>,
    pub updated_at: chrono::DateTime<Utc>,
}

#[derive(Debug)]
pub struct BatchWorkflow {
    pub id: Uuid,
    pub name: String,
    pub tasks: Vec<BatchTask>,
}

impl BatchWorkflow {
    pub fn new(id: Uuid, name: String) -> Self {
        Self {
            id,
            name,
            tasks: Vec::new(),
        }
    }

    pub fn add_task(&mut self, task: BatchTask) {
        self.tasks.push(task);
    }

    pub fn get_execution_order(&self) -> Result<Vec<Uuid>, String> {
        let mut visited = std::collections::HashSet::new();
        let mut temp_visited = std::collections::HashSet::new();
        let mut result = Vec::new();

        // Build dependency map
        let mut task_map: HashMap<Uuid, &BatchTask> = HashMap::new();
        for task in &self.tasks {
            task_map.insert(task.id, task);
        }

        fn visit(
            task_id: Uuid,
            visited: &mut std::collections::HashSet<Uuid>,
            temp_visited: &mut std::collections::HashSet<Uuid>,
            result: &mut Vec<Uuid>,
            task_map: &HashMap<Uuid, &BatchTask>,
        ) -> Result<(), String> {
            if temp_visited.contains(&task_id) {
                return Err("Circular dependency detected".to_string());
            }
            if visited.contains(&task_id) {
                return Ok(());
            }

            temp_visited.insert(task_id);

            if let Some(task) = task_map.get(&task_id) {
                for dep in &task.dependencies {
                    visit(dep.task_id, visited, temp_visited, result, task_map)?;
                }
            }

            temp_visited.remove(&task_id);
            visited.insert(task_id);
            result.push(task_id);

            Ok(())
        }

        for task in &self.tasks {
            if !visited.contains(&task.id) {
                visit(task.id, &mut visited, &mut temp_visited, &mut result, &task_map)?;
            }
        }

        Ok(result)
    }
}

// Simple in-memory storage for testing
#[derive(Debug, Clone)]
pub struct WorkflowState {
    pub workflow_id: Uuid,
    pub current_tasks: Vec<Uuid>,
    pub completed_tasks: Vec<Uuid>,
    pub failed_tasks: Vec<Uuid>,
    pub checkpoints: Vec<serde_json::Value>,
    pub metadata: serde_json::Value,
    pub created_at: chrono::DateTime<Utc>,
    pub updated_at: chrono::DateTime<Utc>,
}

pub struct SimpleStorage {
    states: Arc<std::sync::Mutex<HashMap<Uuid, WorkflowState>>>,
}

impl SimpleStorage {
    pub fn new() -> Self {
        Self {
            states: Arc::new(std::sync::Mutex::new(HashMap::new())),
        }
    }

    pub async fn save_workflow_state(&self, state: &WorkflowState) -> Result<(), String> {
        let mut states = self.states.lock().unwrap();
        states.insert(state.workflow_id, state.clone());
        Ok(())
    }

    pub async fn load_workflow_state(&self, workflow_id: Uuid) -> Result<WorkflowState, String> {
        let states = self.states.lock().unwrap();
        states.get(&workflow_id)
            .cloned()
            .ok_or_else(|| "Workflow state not found".to_string())
    }

    pub async fn list_workflow_states(&self) -> Result<Vec<Uuid>, String> {
        let states = self.states.lock().unwrap();
        Ok(states.keys().cloned().collect())
    }
}

// Simple metrics collector
#[derive(Debug, Clone)]
pub struct WorkflowEvent {
    pub workflow_id: Uuid,
    pub task_id: Option<Uuid>,
    pub event_type: String,
    pub metadata: serde_json::Value,
    pub timestamp: chrono::DateTime<Utc>,
}

#[derive(Debug, Clone)]
pub struct WorkflowMetrics {
    pub total_tasks: u32,
    pub completed_tasks: u32,
    pub failed_tasks: u32,
    pub total_duration_ms: u64,
}

pub struct SimpleMetricsCollector {
    events: Arc<std::sync::Mutex<Vec<WorkflowEvent>>>,
}

impl SimpleMetricsCollector {
    pub fn new() -> Self {
        Self {
            events: Arc::new(std::sync::Mutex::new(Vec::new())),
        }
    }

    pub async fn record_event(&self, event: WorkflowEvent) {
        let mut events = self.events.lock().unwrap();
        events.push(event);
    }

    pub async fn get_workflow_metrics(&self, workflow_id: Uuid) -> Result<WorkflowMetrics, String> {
        let events = self.events.lock().unwrap();
        let workflow_events: Vec<_> = events
            .iter()
            .filter(|e| e.workflow_id == workflow_id)
            .collect();

        let task_events: Vec<_> = workflow_events
            .iter()
            .filter(|e| e.task_id.is_some())
            .collect();

        let mut unique_tasks = std::collections::HashSet::new();
        let mut completed = 0;
        let mut failed = 0;

        for event in &task_events {
            if let Some(task_id) = event.task_id {
                unique_tasks.insert(task_id);
                match event.event_type.as_str() {
                    "task_completed" => completed += 1,
                    "task_failed" => failed += 1,
                    _ => {}
                }
            }
        }

        let start_time = workflow_events
            .iter()
            .map(|e| e.timestamp)
            .min()
            .unwrap_or(Utc::now());

        let end_time = workflow_events
            .iter()
            .filter(|e| e.event_type == "workflow_completed")
            .map(|e| e.timestamp)
            .max();

        let duration = if let Some(end) = end_time {
            (end - start_time).num_milliseconds().max(0) as u64
        } else {
            (Utc::now() - start_time).num_milliseconds().max(0) as u64
        };

        Ok(WorkflowMetrics {
            total_tasks: unique_tasks.len() as u32,
            completed_tasks: completed,
            failed_tasks: failed,
            total_duration_ms: duration,
        })
    }

    pub async fn get_workflow_events(&self, workflow_id: Uuid) -> Result<Vec<WorkflowEvent>, String> {
        let events = self.events.lock().unwrap();
        Ok(events
            .iter()
            .filter(|e| e.workflow_id == workflow_id)
            .cloned()
            .collect())
    }
}

// Integration tests
#[tokio::test]
async fn test_complete_batch_workflow() {
    let storage = Arc::new(SimpleStorage::new());
    let metrics = Arc::new(SimpleMetricsCollector::new());

    // Create a complete infrastructure deployment workflow
    let workflow_id = Uuid::new_v4();
    let mut workflow = BatchWorkflow::new(workflow_id, "test-infrastructure".to_string());

    // Add server provisioning task
    let server_task_id = Uuid::new_v4();
    workflow.add_task(BatchTask {
        id: server_task_id,
        name: "upcloud-server-1".to_string(),
        task_type: TaskType::Server,
        provider: "upcloud".to_string(),
        config: serde_json::json!({
            "zone": "fi-hel1",
            "plan": "1xCPU-1GB",
            "image": "Ubuntu 24.04"
        }),
        dependencies: vec![],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    // Add taskserv installation
    let k8s_task_id = Uuid::new_v4();
    workflow.add_task(BatchTask {
        id: k8s_task_id,
        name: "kubernetes-installation".to_string(),
        task_type: TaskType::Taskserv,
        provider: "kubernetes".to_string(),
        config: serde_json::json!({
            "version": "1.31.0",
            "cni": "cilium"
        }),
        dependencies: vec![TaskDependency {
            task_id: server_task_id,
            dependency_type: "requires".to_string(),
        }],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    // Add cluster deployment
    let cluster_task_id = Uuid::new_v4();
    workflow.add_task(BatchTask {
        id: cluster_task_id,
        name: "web-cluster".to_string(),
        task_type: TaskType::Cluster,
        provider: "kubernetes".to_string(),
        config: serde_json::json!({
            "namespace": "web",
            "replicas": 3
        }),
        dependencies: vec![TaskDependency {
            task_id: k8s_task_id,
            dependency_type: "requires".to_string(),
        }],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    // Save initial workflow state
    let state = WorkflowState {
        workflow_id,
        current_tasks: workflow.tasks.iter().map(|t| t.id).collect(),
        completed_tasks: vec![],
        failed_tasks: vec![],
        checkpoints: vec![],
        metadata: serde_json::json!({"test": "integration"}),
        created_at: Utc::now(),
        updated_at: Utc::now(),
    };

    storage.save_workflow_state(&state).await.unwrap();

    // Test dependency resolution
    let execution_order = workflow.get_execution_order().unwrap();
    assert_eq!(execution_order.len(), 3);

    // Verify dependency order
    let server_pos = execution_order.iter().position(|&id| id == server_task_id).unwrap();
    let k8s_pos = execution_order.iter().position(|&id| id == k8s_task_id).unwrap();
    let cluster_pos = execution_order.iter().position(|&id| id == cluster_task_id).unwrap();

    assert!(server_pos < k8s_pos);
    assert!(k8s_pos < cluster_pos);

    // Record workflow start
    metrics.record_event(WorkflowEvent {
        workflow_id,
        task_id: None,
        event_type: "workflow_started".to_string(),
        metadata: serde_json::json!({"name": "test-infrastructure"}),
        timestamp: Utc::now(),
    }).await;

    // Simulate task execution in correct order
    for task_id in execution_order {
        let task = workflow.tasks.iter_mut().find(|t| t.id == task_id).unwrap();

        // Mark task as running
        task.state = TaskState::Running;
        metrics.record_event(WorkflowEvent {
            workflow_id,
            task_id: Some(task_id),
            event_type: "task_started".to_string(),
            metadata: serde_json::json!({"task_name": task.name}),
            timestamp: Utc::now(),
        }).await;

        // Simulate execution time
        sleep(Duration::from_millis(50)).await;

        // Mark task as completed
        task.state = TaskState::Completed;
        task.updated_at = Utc::now();

        metrics.record_event(WorkflowEvent {
            workflow_id,
            task_id: Some(task_id),
            event_type: "task_completed".to_string(),
            metadata: serde_json::json!({"task_name": task.name}),
            timestamp: Utc::now(),
        }).await;
    }

    // Record workflow completion
    metrics.record_event(WorkflowEvent {
        workflow_id,
        task_id: None,
        event_type: "workflow_completed".to_string(),
        metadata: serde_json::json!({"total_tasks": 3}),
        timestamp: Utc::now(),
    }).await;

    // Verify all tasks completed successfully
    for task in &workflow.tasks {
        assert_eq!(task.state, TaskState::Completed);
    }

    // Verify metrics were collected
    let workflow_metrics = metrics.get_workflow_metrics(workflow_id).await.unwrap();
    assert_eq!(workflow_metrics.total_tasks, 3);
    assert_eq!(workflow_metrics.completed_tasks, 3);
    assert_eq!(workflow_metrics.failed_tasks, 0);
    assert!(workflow_metrics.total_duration_ms > 100); // At least our sleep time
}

#[tokio::test]
async fn test_mixed_provider_deployment() {
    let workflow_id = Uuid::new_v4();
    let mut workflow = BatchWorkflow::new(workflow_id, "mixed-provider".to_string());

    let upcloud_task_id = Uuid::new_v4();
    let aws_task_id = Uuid::new_v4();

    // UpCloud server
    workflow.add_task(BatchTask {
        id: upcloud_task_id,
        name: "upcloud-web-server".to_string(),
        task_type: TaskType::Server,
        provider: "upcloud".to_string(),
        config: serde_json::json!({
            "zone": "fi-hel1",
            "plan": "2xCPU-4GB"
        }),
        dependencies: vec![],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    // AWS resources
    workflow.add_task(BatchTask {
        id: aws_task_id,
        name: "aws-s3-storage".to_string(),
        task_type: TaskType::Server,
        provider: "aws".to_string(),
        config: serde_json::json!({
            "service": "s3",
            "bucket": "test-deployment-assets",
            "region": "eu-north-1"
        }),
        dependencies: vec![],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    let execution_order = workflow.get_execution_order().unwrap();
    assert_eq!(execution_order.len(), 2);

    // Both tasks should be executable in parallel since no dependencies
    for task_id in execution_order {
        let task = workflow.tasks.iter_mut().find(|t| t.id == task_id).unwrap();
        task.state = TaskState::Completed;
    }

    // Verify mixed provider execution
    let upcloud_task = workflow.tasks.iter().find(|t| t.provider == "upcloud").unwrap();
    let aws_task = workflow.tasks.iter().find(|t| t.provider == "aws").unwrap();

    assert_eq!(upcloud_task.state, TaskState::Completed);
    assert_eq!(aws_task.state, TaskState::Completed);
}

#[tokio::test]
async fn test_complex_dependency_resolution() {
    let workflow_id = Uuid::new_v4();
    let mut workflow = BatchWorkflow::new(workflow_id, "complex-deps".to_string());

    // Create complex dependency chain:
    // Server1 -> K8s -> Storage -> App
    // Server2 -> K8s -> Networking -> App

    let server1_id = Uuid::new_v4();
    let server2_id = Uuid::new_v4();
    let k8s_id = Uuid::new_v4();
    let storage_id = Uuid::new_v4();
    let network_id = Uuid::new_v4();
    let app_id = Uuid::new_v4();

    // Add tasks in random order to test dependency resolution
    workflow.add_task(BatchTask {
        id: app_id,
        name: "application".to_string(),
        task_type: TaskType::Cluster,
        provider: "kubernetes".to_string(),
        config: serde_json::json!({}),
        dependencies: vec![
            TaskDependency { task_id: storage_id, dependency_type: "requires".to_string() },
            TaskDependency { task_id: network_id, dependency_type: "requires".to_string() },
        ],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    workflow.add_task(BatchTask {
        id: storage_id,
        name: "storage".to_string(),
        task_type: TaskType::Taskserv,
        provider: "rook-ceph".to_string(),
        config: serde_json::json!({}),
        dependencies: vec![TaskDependency { task_id: k8s_id, dependency_type: "requires".to_string() }],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    workflow.add_task(BatchTask {
        id: network_id,
        name: "networking".to_string(),
        task_type: TaskType::Taskserv,
        provider: "cilium".to_string(),
        config: serde_json::json!({}),
        dependencies: vec![TaskDependency { task_id: k8s_id, dependency_type: "requires".to_string() }],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    workflow.add_task(BatchTask {
        id: k8s_id,
        name: "kubernetes".to_string(),
        task_type: TaskType::Taskserv,
        provider: "kubernetes".to_string(),
        config: serde_json::json!({}),
        dependencies: vec![
            TaskDependency { task_id: server1_id, dependency_type: "requires".to_string() },
            TaskDependency { task_id: server2_id, dependency_type: "requires".to_string() },
        ],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    workflow.add_task(BatchTask {
        id: server1_id,
        name: "server1".to_string(),
        task_type: TaskType::Server,
        provider: "upcloud".to_string(),
        config: serde_json::json!({}),
        dependencies: vec![],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    workflow.add_task(BatchTask {
        id: server2_id,
        name: "server2".to_string(),
        task_type: TaskType::Server,
        provider: "upcloud".to_string(),
        config: serde_json::json!({}),
        dependencies: vec![],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    let execution_order = workflow.get_execution_order().unwrap();
    assert_eq!(execution_order.len(), 6);

    // Verify dependency order
    let server1_pos = execution_order.iter().position(|&id| id == server1_id).unwrap();
    let server2_pos = execution_order.iter().position(|&id| id == server2_id).unwrap();
    let k8s_pos = execution_order.iter().position(|&id| id == k8s_id).unwrap();
    let storage_pos = execution_order.iter().position(|&id| id == storage_id).unwrap();
    let network_pos = execution_order.iter().position(|&id| id == network_id).unwrap();
    let app_pos = execution_order.iter().position(|&id| id == app_id).unwrap();

    // Servers must come before K8s
    assert!(server1_pos < k8s_pos);
    assert!(server2_pos < k8s_pos);

    // K8s must come before storage and networking
    assert!(k8s_pos < storage_pos);
    assert!(k8s_pos < network_pos);

    // Storage and networking must come before app
    assert!(storage_pos < app_pos);
    assert!(network_pos < app_pos);
}

#[tokio::test]
async fn test_rollback_and_recovery() {
    let storage = Arc::new(SimpleStorage::new());

    let workflow_id = Uuid::new_v4();
    let mut workflow = BatchWorkflow::new(workflow_id, "rollback-test".to_string());

    let task1_id = Uuid::new_v4();
    let task2_id = Uuid::new_v4();
    let task3_id = Uuid::new_v4();

    workflow.add_task(BatchTask {
        id: task1_id,
        name: "server-creation".to_string(),
        task_type: TaskType::Server,
        provider: "upcloud".to_string(),
        config: serde_json::json!({}),
        dependencies: vec![],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    workflow.add_task(BatchTask {
        id: task2_id,
        name: "kubernetes-install".to_string(),
        task_type: TaskType::Taskserv,
        provider: "kubernetes".to_string(),
        config: serde_json::json!({}),
        dependencies: vec![TaskDependency { task_id: task1_id, dependency_type: "requires".to_string() }],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    workflow.add_task(BatchTask {
        id: task3_id,
        name: "app-deploy".to_string(),
        task_type: TaskType::Cluster,
        provider: "kubernetes".to_string(),
        config: serde_json::json!({}),
        dependencies: vec![TaskDependency { task_id: task2_id, dependency_type: "requires".to_string() }],
        state: TaskState::Pending,
        created_at: Utc::now(),
        updated_at: Utc::now(),
    });

    // Execute first task successfully
    workflow.tasks.iter_mut().find(|t| t.id == task1_id).unwrap().state = TaskState::Completed;

    // Create checkpoint after first task
    let checkpoint_state = WorkflowState {
        workflow_id,
        current_tasks: vec![task2_id, task3_id],
        completed_tasks: vec![task1_id],
        failed_tasks: vec![],
        checkpoints: vec![serde_json::json!({
            "checkpoint_id": "after-server-creation",
            "completed_tasks": [task1_id],
            "timestamp": Utc::now()
        })],
        metadata: serde_json::json!({"checkpoint": true}),
        created_at: Utc::now(),
        updated_at: Utc::now(),
    };

    storage.save_workflow_state(&checkpoint_state).await.unwrap();

    // Simulate failure on second task
    workflow.tasks.iter_mut().find(|t| t.id == task2_id).unwrap().state = TaskState::Failed;

    // Verify rollback capability
    let recovered_state = storage.load_workflow_state(workflow_id).await.unwrap();
    assert_eq!(recovered_state.completed_tasks.len(), 1);
    assert_eq!(recovered_state.completed_tasks[0], task1_id);
    assert_eq!(recovered_state.checkpoints.len(), 1);

    // Test that rollback preserves completed work
    assert!(recovered_state.completed_tasks.contains(&task1_id));
    assert!(recovered_state.current_tasks.contains(&task2_id));
}

#[tokio::test]
async fn test_state_persistence() {
    let storage = Arc::new(SimpleStorage::new());

    let workflow_id = Uuid::new_v4();
    let state = WorkflowState {
        workflow_id,
        current_tasks: vec![Uuid::new_v4(), Uuid::new_v4()],
        completed_tasks: vec![Uuid::new_v4()],
        failed_tasks: vec![],
        checkpoints: vec![serde_json::json!({"test": "checkpoint"})],
        metadata: serde_json::json!({"backend": "filesystem"}),
        created_at: Utc::now(),
        updated_at: Utc::now(),
    };

    // Save and load state
    storage.save_workflow_state(&state).await.unwrap();
    let loaded_state = storage.load_workflow_state(workflow_id).await.unwrap();

    assert_eq!(loaded_state.workflow_id, workflow_id);
    assert_eq!(loaded_state.current_tasks.len(), 2);
    assert_eq!(loaded_state.completed_tasks.len(), 1);
    assert_eq!(loaded_state.checkpoints.len(), 1);

    // Verify state persistence
    let all_states = storage.list_workflow_states().await.unwrap();
    assert!(all_states.contains(&workflow_id));
}

#[tokio::test]
async fn test_metrics_collection() {
    let metrics = Arc::new(SimpleMetricsCollector::new());
    let workflow_id = Uuid::new_v4();
    let task_id = Uuid::new_v4();

    // Record various events
    metrics.record_event(WorkflowEvent {
        workflow_id,
        task_id: Some(task_id),
        event_type: "workflow_started".to_string(),
        metadata: serde_json::json!({"name": "test-workflow"}),
        timestamp: Utc::now(),
    }).await;

    sleep(Duration::from_millis(10)).await;

    metrics.record_event(WorkflowEvent {
        workflow_id,
        task_id: Some(task_id),
        event_type: "task_started".to_string(),
        metadata: serde_json::json!({"task_name": "test-task"}),
        timestamp: Utc::now(),
    }).await;

    sleep(Duration::from_millis(10)).await;

    metrics.record_event(WorkflowEvent {
        workflow_id,
        task_id: Some(task_id),
        event_type: "task_completed".to_string(),
        metadata: serde_json::json!({"task_name": "test-task", "duration_ms": 100}),
        timestamp: Utc::now(),
    }).await;

    metrics.record_event(WorkflowEvent {
        workflow_id,
        task_id: None,
        event_type: "workflow_completed".to_string(),
        metadata: serde_json::json!({"total_duration_ms": 200}),
        timestamp: Utc::now(),
    }).await;

    // Verify metrics collection
    let workflow_metrics = metrics.get_workflow_metrics(workflow_id).await.unwrap();
    assert_eq!(workflow_metrics.total_tasks, 1);
    assert_eq!(workflow_metrics.completed_tasks, 1);
    assert_eq!(workflow_metrics.failed_tasks, 0);
    assert!(workflow_metrics.total_duration_ms >= 20);

    let events = metrics.get_workflow_events(workflow_id).await.unwrap();
    assert_eq!(events.len(), 4);
    assert!(events.iter().any(|e| e.event_type == "workflow_started"));
    assert!(events.iter().any(|e| e.event_type == "workflow_completed"));
}