use axum::Router;
use axum::routing::{get, post, put};
use std::time::Duration;
use uuid::Uuid;

use erp_core::error::AppResult;
use erp_core::events::EventBus;
use erp_core::module::ErpModule;

use crate::handler::{definition_handler, instance_handler, task_handler};

/// Workflow module implementing the `ErpModule` trait.
///
/// Manages workflow definitions, process instances, tasks,
/// and the token-driven execution engine.
pub struct WorkflowModule;

impl WorkflowModule {
    pub fn new() -> Self {
        Self
    }

    /// Build protected (authenticated) routes for the workflow module.
    pub fn protected_routes<S>() -> Router<S>
    where
        crate::workflow_state::WorkflowState: axum::extract::FromRef<S>,
        S: Clone + Send + Sync + 'static,
    {
        Router::new()
            // Definition routes
            .route(
                "/workflow/definitions",
                get(definition_handler::list_definitions)
                    .post(definition_handler::create_definition),
            )
            .route(
                "/workflow/definitions/{id}",
                get(definition_handler::get_definition).put(definition_handler::update_definition),
            )
            .route(
                "/workflow/definitions/{id}/publish",
                post(definition_handler::publish_definition),
            )
            .route(
                "/workflow/definitions/{id}/deprecate",
                post(definition_handler::deprecate_definition),
            )
            // Instance routes
            .route(
                "/workflow/instances",
                post(instance_handler::start_instance).get(instance_handler::list_instances),
            )
            .route(
                "/workflow/instances/{id}",
                get(instance_handler::get_instance),
            )
            .route(
                "/workflow/instances/{id}/suspend",
                post(instance_handler::suspend_instance),
            )
            .route(
                "/workflow/instances/{id}/resume",
                post(instance_handler::resume_instance),
            )
            .route(
                "/workflow/instances/{id}/terminate",
                post(instance_handler::terminate_instance),
            )
            // Task routes
            .route(
                "/workflow/tasks/pending",
                get(task_handler::list_pending_tasks),
            )
            .route(
                "/workflow/tasks/completed",
                get(task_handler::list_completed_tasks),
            )
            .route(
                "/workflow/tasks/{id}/complete",
                post(task_handler::complete_task),
            )
            .route(
                "/workflow/tasks/{id}/delegate",
                post(task_handler::delegate_task),
            )
            .route(
                "/workflow/tasks/{id}/claim",
                put(task_handler::claim_task),
            )
    }

    /// 启动超时检查后台任务。
    ///
    /// 每 60 秒扫描一次 tasks 表，查找 due_date 已过期但仍处于 pending 状态的任务。
    /// 发现超时任务时发布 `task.timeout` 事件到事件总线，并记录 warning 日志。
    pub fn start_timeout_checker(db: sea_orm::DatabaseConnection, event_bus: EventBus) {
        tokio::spawn(async move {
            let mut interval = tokio::time::interval(Duration::from_secs(60));

            // 首次跳过，等一个完整间隔再执行
            interval.tick().await;

            loop {
                interval.tick().await;

                match crate::engine::timeout::TimeoutChecker::find_all_overdue_tasks_with_details(&db).await {
                    Ok(overdue) => {
                        if !overdue.is_empty() {
                            tracing::warn!(
                                count = overdue.len(),
                                "发现超时未完成的任务，发布 task.timeout 事件"
                            );
                            for (task_id, tenant_id, instance_id, assignee_id) in &overdue {
                                // 发布超时事件
                                let event = erp_core::events::DomainEvent::new(
                                    "task.timeout",
                                    *tenant_id,
                                    erp_core::events::build_event_payload(serde_json::json!({
                                        "task_id": task_id,
                                        "instance_id": instance_id,
                                        "assignee_id": assignee_id,
                                    })),
                                );
                                event_bus.publish(event, &db).await;
                            }
                        }
                    }
                    Err(e) => {
                        tracing::warn!(error = %e, "超时检查任务执行失败");
                    }
                }
            }
        });
    }
}

impl Default for WorkflowModule {
    fn default() -> Self {
        Self::new()
    }
}

#[async_trait::async_trait]
impl ErpModule for WorkflowModule {
    fn name(&self) -> &str {
        "workflow"
    }

    fn version(&self) -> &str {
        env!("CARGO_PKG_VERSION")
    }

    fn dependencies(&self) -> Vec<&str> {
        vec!["auth"]
    }

    fn register_event_handlers(&self, _bus: &EventBus) {
        // 事件处理器已迁移到 on_startup（需要 DB 连接），此处保留空实现以兼容 trait 签名
    }

    async fn on_startup(
        &self,
        ctx: &erp_core::module::ModuleContext,
    ) -> erp_core::error::AppResult<()> {
        let db = ctx.db.clone();
        let bus = ctx.event_bus.clone();

        // 订阅 user. 前缀事件，处理 user.deleted
        let (mut receiver, _handle) = bus.subscribe_filtered("user.".to_string());

        tokio::spawn(async move {
            loop {
                match receiver.recv().await {
                    Some(event) if event.event_type == "user.deleted" => {
                        let user_id = match event.payload.get("user_id").and_then(|v| v.as_str()) {
                            Some(id) => match Uuid::parse_str(id) {
                                Ok(u) => u,
                                Err(e) => {
                                    tracing::warn!(
                                        error = %e,
                                        "user.deleted 事件的 user_id 解析失败，跳过"
                                    );
                                    continue;
                                }
                            },
                            _ => {
                                tracing::warn!("user.deleted 事件缺少 user_id 字段，跳过");
                                continue;
                            }
                        };

                        tracing::info!(
                            user_id = %user_id,
                            tenant_id = %event.tenant_id,
                            "收到 user.deleted 事件，查找并终止相关流程实例"
                        );

                        // 查找该用户有活跃任务的流程实例
                        use sea_orm::{ActiveModelTrait, ColumnTrait, EntityTrait, QueryFilter, Set};
                        use chrono::Utc;

                        // 查找该用户作为 assignee 的 pending 任务
                        let active_tasks = crate::entity::task::Entity::find()
                            .filter(crate::entity::task::Column::TenantId.eq(event.tenant_id))
                            .filter(crate::entity::task::Column::AssigneeId.eq(user_id))
                            .filter(crate::entity::task::Column::Status.eq("pending"))
                            .filter(crate::entity::task::Column::DeletedAt.is_null())
                            .all(&db)
                            .await;

                        match active_tasks {
                            Ok(tasks) if tasks.is_empty() => {
                                tracing::info!(
                                    user_id = %user_id,
                                    "该用户没有活跃的待办任务，无需终止流程"
                                );
                            }
                            Ok(tasks) => {
                                // 收集需要终止的实例 ID
                                let instance_ids: std::collections::HashSet<Uuid> =
                                    tasks.iter().map(|t| t.instance_id).collect();

                                for instance_id in &instance_ids {
                                    // 将实例状态设置为 terminated
                                    let instance = crate::entity::process_instance::Entity::find_by_id(*instance_id)
                                        .one(&db)
                                        .await;

                                    if let Ok(Some(inst)) = instance {
                                        if inst.tenant_id == event.tenant_id
                                            && inst.deleted_at.is_none()
                                            && inst.status == "running"
                                        {
                                            let ver = inst.version;
                                            let mut active: crate::entity::process_instance::ActiveModel = inst.into();
                                            active.status = Set("terminated".to_string());
                                            active.updated_at = Set(Utc::now());
                                            active.version = Set(ver + 1);
                                            match active.update(&db).await {
                                                Ok(_) => {
                                                    tracing::info!(
                                                        instance_id = %instance_id,
                                                        "流程实例已终止（用户被删除）"
                                                    );
                                                }
                                                Err(e) => {
                                                    tracing::warn!(
                                                        instance_id = %instance_id,
                                                        error = %e,
                                                        "终止流程实例失败"
                                                    );
                                                }
                                            }
                                        }
                                    }
                                }
                                tracing::info!(
                                    user_id = %user_id,
                                    instance_count = instance_ids.len(),
                                    task_count = tasks.len(),
                                    "用户删除事件处理完成"
                                );
                            }
                            Err(e) => {
                                tracing::warn!(
                                    error = %e,
                                    "查询用户活跃任务失败"
                                );
                            }
                        }
                    }
                    Some(event) => {
                        // 其他 user. 前缀事件，忽略
                        tracing::debug!(
                            event_type = %event.event_type,
                            "忽略非 user.deleted 事件"
                        );
                    }
                    None => {
                        // 通道关闭，退出循环
                        tracing::info!("Workflow 事件订阅通道已关闭");
                        break;
                    }
                }
            }
        });

        tracing::info!(module = "workflow", "Workflow 事件处理器已注册（监听 user.deleted）");
        Ok(())
    }

    async fn on_tenant_created(
        &self,
        _tenant_id: Uuid,
        _db: &sea_orm::DatabaseConnection,
        _event_bus: &EventBus,
    ) -> AppResult<()> {
        Ok(())
    }

    async fn on_tenant_deleted(
        &self,
        tenant_id: Uuid,
        db: &sea_orm::DatabaseConnection,
    ) -> AppResult<()> {
        use sea_orm::{ColumnTrait, EntityTrait, QueryFilter};

        // Delete in dependency order: variables → tasks → tokens → instances → definitions
        // process_variables
        crate::entity::process_variable::Entity::delete_many()
            .filter(crate::entity::process_variable::Column::TenantId.eq(tenant_id))
            .exec(db)
            .await?;

        // tasks
        crate::entity::task::Entity::delete_many()
            .filter(crate::entity::task::Column::TenantId.eq(tenant_id))
            .exec(db)
            .await?;

        // tokens
        crate::entity::token::Entity::delete_many()
            .filter(crate::entity::token::Column::TenantId.eq(tenant_id))
            .exec(db)
            .await?;

        // process_instances
        crate::entity::process_instance::Entity::delete_many()
            .filter(crate::entity::process_instance::Column::TenantId.eq(tenant_id))
            .exec(db)
            .await?;

        // process_definitions
        crate::entity::process_definition::Entity::delete_many()
            .filter(crate::entity::process_definition::Column::TenantId.eq(tenant_id))
            .exec(db)
            .await?;

        tracing::info!(%tenant_id, "Workflow data cleaned up for deleted tenant");
        Ok(())
    }

    fn as_any(&self) -> &dyn std::any::Any {
        self
    }
}