/**
 * Level 3c: Queue System with Worker Pool
 * 
 * Features:
 * 1. Task queue - register many tasks
 * 2. Worker pool - max concurrent agents
 * 3. Auto-pull - workers take next task when free
 * 4. Priority support - high/normal/low
 * 5. Backpressure - reject when queue full
 */

import { Agent, type AgentTool, type AgentMessage, type AgentEvent } from "@mariozechner/pi-agent-core";
import { registerBuiltInApiProviders } from "@mariozechner/pi-ai";
import type { Model } from "@mariozechner/pi-ai";
import { exec } from "child_process";

// ============== CONFIG ==============
const OPENROUTER_API_KEY = process.env.OPENROUTER_API_KEY || "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";
process.env.OPENROUTER_API_KEY = OPENROUTER_API_KEY;

const model: Model<"openai-responses"> = {
  id: "stepfun/step-3.5-flash:free",
  name: "Step-3.5 Flash (Free)",
  api: "openai-responses",
  provider: "openrouter",
  baseUrl: "https://openrouter.ai/api/v1",
  reasoning: false,
  input: ["text"],
  output: ["text"],
  cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
  contextWindow: 128000,
  maxTokens: 8192,
};

// ============== TASK ==============
type TaskPriority = "high" | "normal" | "low";

interface QueuedTask {
  id: string;
  message: string;
  priority: TaskPriority;
  createdAt: number;
  status: "queued" | "running" | "completed" | "failed";
}

// ============== QUEUE ==============
class TaskQueue {
  private queue: QueuedTask[] = [];
  private maxSize: number;

  constructor(maxSize: number = 100) {
    this.maxSize = maxSize;
  }

  // Add task to queue
  enqueue(task: QueuedTask): boolean {
    if (this.queue.length >= this.maxSize) {
      return false; // Queue full - backpressure
    }

    // Insert based on priority
    let insertIndex = this.queue.length;
    const priorityOrder = { high: 0, normal: 1, low: 2 };
    
    for (let i = 0; i < this.queue.length; i++) {
      if (priorityOrder[task.priority] < priorityOrder[this.queue[i].priority]) {
        insertIndex = i;
        break;
      }
    }

    this.queue.splice(insertIndex, 0, task);
    return true;
  }

  // Get next task (highest priority first)
  dequeue(): QueuedTask | undefined {
    const task = this.queue.shift();
    if (task) {
      task.status = "running";
    }
    return task;
  }

  // Peek at next task without removing
  peek(): QueuedTask | undefined {
    return this.queue[0];
  }

  // Get queue size
  size(): number {
    return this.queue.length;
  }

  // Get all queued tasks
  getAll(): QueuedTask[] {
    return [...this.queue];
  }

  // Update task status
  updateStatus(id: string, status: "completed" | "failed") {
    const task = this.queue.find(t => t.id === id);
    if (task) {
      task.status = status;
    }
  }
}

// ============== WORKER (SHADOW) ==============
class Worker {
  public id: string;
  public status: "idle" | "busy" = "idle";
  private agent: Agent;

  constructor(id: string, worktreePath: string) {
    this.id = id;
    this.agent = new Agent({
      initialState: {
        systemPrompt: "You are a helpful coding assistant.",
        model: model,
        tools: [] as any,
        messages: [],
      },
      convertToLlm: (messages: AgentMessage[]) => {
        return messages
          .filter((m) => m.role === "user" || m.role === "assistant" || m.role === "toolResult")
          .map((m) => ({ role: m.role, content: m.content }));
      },
    });

    this.agent.subscribe((event) => {
      if (event.type === "agent_start") this.status = "busy";
      if (event.type === "agent_end") this.status = "idle";
    });
  }

  async run(task: QueuedTask): Promise<string> {
    this.status = "busy";
    await this.agent.prompt(task.message);
    this.status = "idle";
    return "completed";
  }

  abort() {
    this.agent.abort();
  }
}

// ============== QUEUE SYSTEM ==============
class QueueSystem {
  private queue: TaskQueue;
  private workers: Worker[] = [];
  private maxWorkers: number;
  private maxQueueSize: number;
  private running = false;

  constructor(maxWorkers: number = 2, maxQueueSize: number = 100) {
    this.maxWorkers = maxWorkers;
    this.maxQueueSize = maxQueueSize;
    this.queue = new TaskQueue(maxQueueSize);
  }

  // Submit a task to queue
  submit(message: string, priority: TaskPriority = "normal"): boolean {
    const task: QueuedTask = {
      id: `task-${Date.now()}-${Math.random().toString(36).substr(2, 5)}`,
      message,
      priority,
      createdAt: Date.now(),
      status: "queued",
    };

    const success = this.queue.enqueue(task);
    if (success) {
      console.log(`📥 Queued: ${task.id} (priority: ${priority}, queue: ${this.queue.size()})`);
      this.dispatch(); // Try to dispatch immediately
    } else {
      console.log(`❌ Queue full! Rejected: ${task.id}`);
    }
    return success;
  }

  // Dispatch task to available worker
  private dispatch() {
    // Find idle workers
    const idleWorkers = this.workers.filter(w => w.status === "idle");
    
    // Get next task
    const task = this.queue.peek();
    
    if (!task || idleWorkers.length === 0) {
      return; // No task or no workers
    }

    // Assign task to first idle worker
    const worker = idleWorkers[0];
    this.queue.dequeue(); // Remove from queue
    
    console.log(`▶️ Dispatching ${task.id} to worker ${worker.id}`);
    
    // Run task
    worker.run(task).then(() => {
      task.status = "completed";
      console.log(`✅ Completed: ${task.id}`);
      
      // Check for more tasks
      this.dispatch();
    }).catch((error) => {
      task.status = "failed";
      console.log(`❌ Failed: ${task.id} - ${error.message}`);
      
      // Check for more tasks
      this.dispatch();
    });
  }

  // Add a worker
  addWorker(id: string, worktreePath: string): Worker {
    const worker = new Worker(id, worktreePath);
    this.workers.push(worker);
    console.log(`👷 Added worker: ${id} (total: ${this.workers.length})`);
    
    // Try to dispatch
    this.dispatch();
    
    return worker;
  }

  // Remove a worker
  removeWorker(id: string) {
    const worker = this.workers.find(w => w.id === id);
    if (worker) {
      worker.abort();
      this.workers = this.workers.filter(w => w.id !== id);
      console.log(`👷 Removed worker: ${id}`);
    }
  }

  // Get stats
  getStats() {
    return {
      queueSize: this.queue.size(),
      maxQueueSize: this.maxQueueSize,
      workers: this.workers.length,
      idleWorkers: this.workers.filter(w => w.status === "idle").length,
      busyWorkers: this.workers.filter(w => w.status === "busy").length,
      maxWorkers: this.maxWorkers,
      queuedTasks: this.queue.getAll().map(t => ({
        id: t.id,
        priority: t.priority,
        status: t.status,
      })),
    };
  }

  // Start the queue processor
  start() {
    this.running = true;
    console.log(`🚀 Queue system started (max ${this.maxWorkers} workers)`);
  }

  // Stop the queue processor
  stop() {
    this.running = false;
    this.workers.forEach(w => w.abort());
    console.log("🛑 Queue system stopped");
  }
}

// ============== TESTS ==============
async function testSequential() {
  console.log("\n" + "=" .repeat(50));
  console.log("TEST 1: Sequential (1 worker, multiple tasks)");
  console.log("=" .repeat(50));

  const queue = new QueueSystem(1, 50);
  queue.start();
  queue.addWorker("worker-1", "/tmp");

  // Submit 3 tasks
  queue.submit("Say 'Task 1'", "normal");
  queue.submit("Say 'Task 2'", "normal");
  queue.submit("Say 'Task 3'", "normal");

  // Wait for tasks to complete
  await new Promise(resolve => setTimeout(resolve, 30000));

  console.log("\n📊 Stats:", queue.getStats());
  queue.stop();
}

async function testParallel() {
  console.log("\n" + "=" .repeat(50));
  console.log("TEST 2: Parallel (2 workers, multiple tasks)");
  console.log("=" .repeat(50));

  const queue = new QueueSystem(2, 50);
  queue.start();
  queue.addWorker("worker-1", "/tmp");
  queue.addWorker("worker-2", "/tmp");

  // Submit 4 tasks
  queue.submit("Say 'Task A'", "normal");
  queue.submit("Say 'Task B'", "normal");
  queue.submit("Say 'Task C'", "normal");
  queue.submit("Say 'Task D'", "normal");

  // Wait for tasks to complete
  await new Promise(resolve => setTimeout(resolve, 30000));

  console.log("\n📊 Stats:", queue.getStats());
  queue.stop();
}

async function testPriority() {
  console.log("\n" + "=" .repeat(50));
  console.log("TEST 3: Priority (high priority first)");
  console.log("=" .repeat(50));

  const queue = new QueueSystem(1, 50);
  queue.start();
  queue.addWorker("worker-1", "/tmp");

  // Submit in random order with different priorities
  queue.submit("Say 'Normal 1'", "normal");
  queue.submit("Say 'Low'", "low");
  queue.submit("Say 'High 1'", "high");
  queue.submit("Say 'Normal 2'", "normal");
  queue.submit("Say 'High 2'", "high");

  console.log("\n📊 Queue order:", queue.getStats().queuedTasks.map(t => `${t.priority}:${t.id.slice(-3)}`));

  // Wait for tasks to complete
  await new Promise(resolve => setTimeout(resolve, 40000));

  console.log("\n📊 Stats:", queue.getStats());
  queue.stop();
}

async function testBackpressure() {
  console.log("\n" + "=" .repeat(50));
  console.log("TEST 4: Backpressure (queue full)");
  console.log("=" .repeat(50));

  // Very small queue (3 max)
  const queue = new QueueSystem(1, 3);
  queue.start();
  queue.addWorker("worker-1", "/tmp");

  // Submit 5 tasks (should reject 2)
  const results = [];
  results.push(queue.submit("Task 1", "normal"));
  results.push(queue.submit("Task 2", "normal"));
  results.push(queue.submit("Task 3", "normal"));
  results.push(queue.submit("Task 4", "normal")); // Should fail
  results.push(queue.submit("Task 5", "normal")); // Should fail

  console.log("\n📊 Submit results:", results.map((r, i) => `Task ${i+1}: ${r ? '✅' : '❌'}`).join(", "));
  console.log("\n📊 Stats:", queue.getStats());

  // Wait a bit then cleanup
  await new Promise(resolve => setTimeout(resolve, 5000));
  queue.stop();
}

// ============== MAIN ==============
async function main() {
  console.log("🧪 Level 3c: Queue System with Worker Pool\n");

  registerBuiltInApiProviders();

  await testSequential();
  await new Promise(resolve => setTimeout(resolve, 3000));

  await testParallel();
  await new Promise(resolve => setTimeout(resolve, 3000));

  await testPriority();
  await new Promise(resolve => setTimeout(resolve, 3000));

  await testBackpressure();

  console.log("\n✅ All tests complete!");
}

main().catch(console.error);