#!/usr/bin/env python
"""
Multi-GPU launcher for MD simulations.

Launches multiple experiment_runner.py processes across multiple GPUs,
each with a different index and proper logging.
"""

import argparse
import os
import subprocess
import time
from pathlib import Path


def launch_experiment(
    gpu_id: int,
    index: int,
    model_name: str,
    input_dir: str,
    log_dir: Path,
    runner_script: str = "experiment_runner.py",
    extra_args: list = None,
):
    """
    Launch a single experiment on a specific GPU.
    
    Args:
        gpu_id: GPU device ID (0-7)
        index: Experiment index
        model_name: Model name (e.g., 'mace_pyg')
        input_dir: Input directory path
        log_dir: Directory for log files
        runner_script: Script to run (experiment_runner.py or elastic_tensor_runner.py)
        extra_args: Additional arguments to pass to the runner script
    """
    log_file = log_dir / f"gpu{gpu_id}_index{index}.log"
    
    # Build command
    cmd = [
        "python",
        f"md_simulation/{runner_script}",
        "--model_name", model_name,
        "--input_dir", input_dir,
        "--index", str(index),
        "--device", "cuda",
    ]
    
    # Add any extra arguments
    if extra_args:
        cmd.extend(extra_args)
    
    # Set environment with specific GPU
    env = os.environ.copy()
    env["CUDA_VISIBLE_DEVICES"] = str(gpu_id)
    
    # Launch process with logging
    print(f"[GPU {gpu_id}] Launching index {index} -> {log_file}")
    
    with open(log_file, "w") as f:
        f.write(f"=== Experiment Index {index} on GPU {gpu_id} ===\n")
        f.write(f"Command: {' '.join(cmd)}\n")
        f.write(f"CUDA_VISIBLE_DEVICES={gpu_id}\n")
        f.write("=" * 80 + "\n\n")
        f.flush()
        
        process = subprocess.Popen(
            cmd,
            env=env,
            stdout=f,
            stderr=subprocess.STDOUT,
            text=True,
        )
        # wait for 5 seconds to avoid overwhelming the system
        
        time.sleep(5) # wait for 5 seconds to avoid overwhelming the system

    
    return process, log_file


def main():
    parser = argparse.ArgumentParser(
        description="Launch multiple MD simulations across multiple GPUs"
    )
    parser.add_argument(
        "--model_name",
        type=str,
        required=True,
        help="Model name (e.g., mace_pyg, orb, mattersim)",
    )
    parser.add_argument(
        "--input_dir",
        type=str,
        required=True,
        help="Input directory containing structures",
    )
    parser.add_argument(
        "--start_index",
        type=int,
        default=0,
        help="Starting index (default: 0)",
    )
    parser.add_argument(
        "--end_index",
        type=int,
        default=100,
        help="Ending index (exclusive, default: 100)",
    )
    parser.add_argument(
        "--num_gpus",
        type=int,
        default=8,
        help="Number of GPUs to use (default: 8)",
    )
    parser.add_argument(
        "--gpu_offset",
        type=int,
        default=0,
        help="GPU ID offset (default: 0, uses GPUs 0-7). Set to 4 to use GPUs 4-11.",
    )
    parser.add_argument(
        "--log_dir",
        type=str,
        default=None,
        help="Directory for log files (default: auto-generated based on input_dir, e.g., ./logs_minxhtp/)",
    )
    parser.add_argument(
        "--mode",
        type=str,
        choices=["batch", "rolling"],
        default="batch",
        help="Launch mode: 'batch' waits for all GPUs to finish before next batch, "
             "'rolling' launches new job as soon as any GPU is free (default: batch)",
    )
    parser.add_argument(
        "--runner",
        type=str,
        choices=["experiment_runner.py", "elastic_tensor_runner.py"],
        default="experiment_runner.py",
        help="Runner script to use (default: experiment_runner.py for MD simulations)",
    )
    parser.add_argument(
        "--extra_args",
        type=str,
        default="",
        help="Extra arguments to pass to the runner script (e.g., '--runsteps 1000 --timestep 0.5')",
    )
    
    args = parser.parse_args()
    
    # Auto-generate log directory based on input_dir if not specified
    if args.log_dir is None:
        # Extract dataset name from input_dir
        dataset_name = Path(args.input_dir).name.lower()
        args.log_dir = f"./logs_{dataset_name}"
    
    # Create log directory
    log_dir = Path(args.log_dir)
    log_dir.mkdir(parents=True, exist_ok=True)
    
    # Parse extra arguments
    extra_args = args.extra_args.split() if args.extra_args else []
    
    # Add dataset-specific output directory to extra args if not already specified
    dataset_name = Path(args.input_dir).name.lower()
    if not any('--log_dir_base' in arg for arg in extra_args):
        if args.runner == "experiment_runner.py":
            output_dir = f"./results_{dataset_name}"
        else:  # elastic_tensor_runner.py
            output_dir = f"./elastic_{dataset_name}"
        extra_args.extend(["--log_dir_base", output_dir])
    
    # Create list of all indices to process
    indices = list(range(args.start_index, args.end_index))
    total_jobs = len(indices)
    
    # Extract output directory from extra_args for display
    output_dir = None
    for i, arg in enumerate(extra_args):
        if arg == "--log_dir_base" and i + 1 < len(extra_args):
            output_dir = extra_args[i + 1]
            break
    
    print("=" * 80)
    print(f"Multi-GPU Launcher Configuration")
    print("=" * 80)
    print(f"Runner script: {args.runner}")
    print(f"Model: {args.model_name}")
    print(f"Input directory: {args.input_dir}")
    print(f"Indices: {args.start_index} to {args.end_index-1} ({total_jobs} total)")
    print(f"GPUs: {args.num_gpus} (IDs {args.gpu_offset} to {args.gpu_offset + args.num_gpus - 1})")
    print(f"Mode: {args.mode}")
    if args.mode == "batch":
        print(f"  - Launches {args.num_gpus} jobs, waits for all to complete, then next batch")
    else:
        print(f"  - Launches new job as soon as any GPU becomes free")
    print(f"Launch logs: {log_dir}")
    if output_dir:
        print(f"Results output: {output_dir}")
    if extra_args and not (len(extra_args) == 2 and extra_args[0] == "--log_dir_base"):
        # Only show extra args if there are more than just log_dir_base
        print(f"Extra arguments: {' '.join(extra_args)}")
    print("=" * 80)
    print()
    
    # Track progress
    completed = 0
    failed = 0
    current_idx = 0
    
    # Main loop
    try:
        if args.mode == "batch":
            # Batch mode: Launch full batch, wait for all to complete, repeat
            batch_num = 1
            while current_idx < total_jobs:
                batch_start = current_idx
                batch_end = min(current_idx + args.num_gpus, total_jobs)
                batch_size = batch_end - batch_start
                
                print("=" * 80)
                print(f"Batch {batch_num}: Launching indices {indices[batch_start]} to {indices[batch_end-1]}")
                print("=" * 80)
                
                # Launch batch
                active_processes = {}
                for i in range(batch_size):
                    gpu_id = args.gpu_offset + i
                    index = indices[current_idx]
                    
                    process, log_file = launch_experiment(
                        gpu_id=gpu_id,
                        index=index,
                        model_name=args.model_name,
                        input_dir=args.input_dir,
                        log_dir=log_dir,
                        runner_script=args.runner,
                        extra_args=extra_args,
                    )
                    
                    active_processes[process] = (gpu_id, index, log_file)
                    current_idx += 1
                    time.sleep(0.5)
                
                print(f"\nBatch {batch_num} launched ({batch_size} jobs). Waiting for completion...\n")
                
                # Wait for all jobs in batch to complete
                while active_processes:
                    completed_processes = []
                    for process, (gpu_id, index, log_file) in active_processes.items():
                        poll = process.poll()
                        if poll is not None:
                            completed_processes.append(process)
                            if poll == 0:
                                print(f"[GPU {gpu_id}] ✓ Index {index} completed successfully")
                                completed += 1
                            else:
                                print(f"[GPU {gpu_id}] ✗ Index {index} failed with exit code {poll}")
                                print(f"          Check log: {log_file}")
                                failed += 1
                    
                    for process in completed_processes:
                        del active_processes[process]
                    
                    if active_processes:
                        time.sleep(2)
                
                print(f"\nBatch {batch_num} completed!")
                print(f"Progress: {completed} completed, {failed} failed, {total_jobs - current_idx} remaining\n")
                batch_num += 1
        
        else:
            # Rolling mode: Launch new job as soon as any GPU is free
            active_processes = {}
            
            while current_idx < total_jobs or active_processes:
                # Launch new jobs if slots available
                while current_idx < total_jobs and len(active_processes) < args.num_gpus:
                    gpu_id = args.gpu_offset + (current_idx % args.num_gpus)
                    index = indices[current_idx]
                    
                    process, log_file = launch_experiment(
                        gpu_id=gpu_id,
                        index=index,
                        model_name=args.model_name,
                        input_dir=args.input_dir,
                        log_dir=log_dir,
                        runner_script=args.runner,
                        extra_args=extra_args,
                    )
                    
                    active_processes[process] = (gpu_id, index, log_file)
                    current_idx += 1
                    time.sleep(0.5)
                
                # Check for completed processes
                completed_processes = []
                for process, (gpu_id, index, log_file) in active_processes.items():
                    poll = process.poll()
                    if poll is not None:
                        completed_processes.append(process)
                        if poll == 0:
                            print(f"[GPU {gpu_id}] ✓ Index {index} completed successfully")
                            completed += 1
                        else:
                            print(f"[GPU {gpu_id}] ✗ Index {index} failed with exit code {poll}")
                            print(f"          Check log: {log_file}")
                            failed += 1
                
                for process in completed_processes:
                    del active_processes[process]
                
                # Progress update
                print(f"\nProgress: {completed} completed, {failed} failed, "
                      f"{len(active_processes)} running, "
                      f"{total_jobs - current_idx} pending\n")
                
                time.sleep(5)
    
    except KeyboardInterrupt:
        print("\n\nInterrupted by user. Terminating active processes...")
        if 'active_processes' in locals():
            for process in active_processes:
                process.terminate()
            for process in active_processes:
                try:
                    process.wait(timeout=10)
                except subprocess.TimeoutExpired:
                    process.kill()
        print("All processes terminated.")
        return
    
    print("\n" + "=" * 80)
    print("All jobs completed!")
    print(f"Successful: {completed}/{total_jobs}")
    print(f"Failed: {failed}/{total_jobs}")
    print(f"Launch logs: {log_dir}")
    if output_dir:
        print(f"Results: {output_dir}")
    print("=" * 80)


if __name__ == "__main__":
    main()