import inspect
import io
import os
import shutil
import tempfile
import threading
import uuid
import warnings
from datetime import datetime
from typing import Callable, Dict

import markdown
import matplotlib.pyplot as plt
import numpy as np
import orjson
import pandas as pd
from flask import Flask, Response, render_template, request, send_file
from selector.methods.distance import DISE, MaxMin, MaxSum, OptiSim
from selector.methods.partition import GridPartition, Medoid
from selector.methods.similarity import NSimilarity
from selector.measures.diversity import compute_diversity
from sklearn.metrics import pairwise_distances
from werkzeug.utils import secure_filename

# Constants
UPLOAD_FOLDER = "uploads"
ALLOWED_EXTENSIONS = {"txt", "npz", "xlsx", "xls"}

app = Flask(__name__)
app.config["MAX_CONTENT_LENGTH"] = 32 * 1024 * 1024  # 32MB max file size
app.config["UPLOAD_FOLDER"] = UPLOAD_FOLDER
file_lock = threading.Lock()

# Ensure upload directory exists
os.makedirs(app.config["UPLOAD_FOLDER"], exist_ok=True)

ALLOWED_EXTENSIONS = {"txt", "npz", "xlsx", "xls"}

# Map algorithm names to their functions
SELECTION_ALGORITHM_MAP = {
    # Distance-based methods
    "MaxMin": MaxMin,
    "MaxSum": MaxSum,
    "OptiSim": OptiSim,
    "DISE": DISE,
    # Partition-based methods
    "GridPartition": GridPartition,
    # Similarity-based methods
    "NSimilarity": NSimilarity,
}


def allowed_file(filename):
    """Check if file extension is allowed."""
    return "." in filename and filename.rsplit(".", 1)[1].lower() in ALLOWED_EXTENSIONS

def get_unique_upload_dir():
    """Create a unique directory for each upload session."""
    unique_dir = os.path.join(app.config["UPLOAD_FOLDER"], str(uuid.uuid4()))
    os.makedirs(unique_dir, exist_ok=True)
    os.chmod(unique_dir, 0o777)  # Full permissions for Docker container
    return unique_dir

def clean_upload_dir(upload_dir):
    """Clean up upload directory after processing."""
    try:
        if os.path.exists(upload_dir):
            shutil.rmtree(upload_dir)
    except Exception as e:
        print(f"Error cleaning upload directory: {e}")

def load_data(filepath):
    """Load data from various file formats."""
    try:
        ext = filepath.rsplit(".", 1)[1].lower()
        if ext == "npz":
            with np.load(filepath) as data:
                return data["arr_0"] if "arr_0" in data else next(iter(data.values()))
        elif ext == "txt":
            return np.loadtxt(filepath)
        elif ext in ["xlsx", "xls"]:
            df = pd.read_excel(filepath)
            return df.to_numpy()
    except Exception as e:
        raise ValueError(f"Error loading file {filepath}: {str(e)}")


def create_json_response(data, status=200):
    """Create a JSON response using orjson for better numpy array handling"""
    return Response(
        orjson.dumps(data, option=orjson.OPT_SERIALIZE_NUMPY, default=str),
        status=status,
        mimetype="application/json",
    )


def read_markdown_file(filename):
    """Read and convert markdown file to HTML."""
    filepath = os.path.join(os.path.dirname(__file__), "md_files", filename)
    try:
        with open(filepath, "r", encoding="utf-8") as f:
            content = f.read()

            # Pre-process math blocks to protect them
            # content = content.replace('\\\\', '\\\\\\\\')  # Escape backslashes in math

            # Convert markdown to HTML with math and table support
            md = markdown.Markdown(extensions=["tables", "fenced_code", "codehilite", "attr_list"])

            # First pass: convert markdown to HTML
            html = md.convert(content)

            # Post-process math blocks
            # Handle display math ($$...$$)
            html = html.replace("<p>$$", '<div class="math-block">$$')
            html = html.replace("$$</p>", "$$</div>")

            # Handle inline math ($...$)
            # We don't need special handling for inline math as MathJax will handle it

            return html
    except Exception as e:
        print(f"Error reading markdown file {filename}: {e}")
        return f"<p>Error loading content: {str(e)}</p>"


def get_default_parameters(func):
    """Get default parameters for a function from its signature."""
    sig = inspect.signature(func)
    defaults = {}

    for name, param in sig.parameters.items():
        if name == "self" or name == "fun_dist":  # Skip self and dist_metric
            continue
        if param.default is not param.empty:
            defaults[name] = param.default

    return defaults


@app.route("/get_default_params/<algorithm>")
def get_default_params(algorithm):
    """API endpoint to get default parameters for an algorithm."""
    if algorithm not in SELECTION_ALGORITHM_MAP:
        return create_json_response({"error": f"Unknown algorithm: {algorithm}"}, 400)

    try:
        # Get the algorithm class
        algorithm_class = SELECTION_ALGORITHM_MAP[algorithm]
        # Get default parameters from __init__
        params = get_default_parameters(algorithm_class.__init__)
        return create_json_response(params)
    except Exception as e:
        return create_json_response({"error": f"Error getting parameters: {str(e)}"}, 500)


@app.route("/get_default_selection_params/<algorithm>")
def get_default_selection_params(algorithm):
    """API endpoint to get default parameters for a selection algorithm."""
    if algorithm not in SELECTION_ALGORITHM_MAP:
        return create_json_response({"error": f"Algorithm unsupported: {algorithm}"}, 400)

    try:
        return create_json_response(get_default_selection_params(algorithm))
    except Exception as e:
        return create_json_response({"error": f"Error getting parameters: {str(e)}"}, 500)


@app.route("/")
def home():
    return render_template("index.html")


@app.route("/md/<filename>")
def get_markdown(filename):
    """Serve markdown files as HTML."""
    if not filename.endswith(".md"):
        filename = filename + ".md"
    html = read_markdown_file(filename)
    return create_json_response({"html": html})


def process_selection(arr, algorithm, parameters, dist_metric):
    """
    Process feature matrix using the specified selection algorithm.

    Parameters
    ----------
    arr : np.ndarray
        Input feature matrix
    algorithm : str
        Name of the selection algorithm to use
    parameters : dict
        Parameters for the algorithm
    dist_metric : str, optional
        Distance function to use.

    Returns
    -------
    dict
        Dictionary containing results and any warnings
    """
    result = {"success": False, "error": None, "warnings": [], "indices": None}

    try:
        # Get the algorithm class
        algorithm_class = SELECTION_ALGORITHM_MAP.get(algorithm)

        if algorithm_class is None:
            raise ValueError(f"Unknown algorithm: {algorithm}")

        # Get size parameter
        size = parameters.pop('size', None)
        if size is None:
            raise ValueError("Subset size must be specified")

        try:
            size = int(size)
            if size < 1:
                raise ValueError
        except (TypeError, ValueError):
            raise ValueError("Subset size must be a positive integer")

        # Validate size against array dimensions
        if size > arr.shape[0]:
            raise ValueError(f"Subset size ({size}) cannot be larger than the number of samples ({arr.shape[0]})")

        # Handle distance-based methods differently
        is_distance_based = algorithm in ["MaxMin", "MaxSum", "OptiSim", "DISE"]

        # Convert array to float for computations
        arr_float = arr.astype(float)

        # Compute or prepare the input matrix
        if is_distance_based:
            # For distance-based methods, compute distance matrix
            try:
                if dist_metric and dist_metric != "":
                    # Use specified distance metric
                    arr_dist = pairwise_distances(arr_float, metric=dist_metric)
                else:
                    # Default to euclidean distance
                    arr_dist = pairwise_distances(arr_float, metric='euclidean')
            except Exception as e:
                raise ValueError(f"Error computing distance matrix: {str(e)}")
        else:
            # For non-distance-based methods, use the original float array
            arr_dist = arr_float

        # Handle special case for GridPartition
        if algorithm == "GridPartition":
            # Ensure nbins_axis is provided and is an integer
            nbins_axis = parameters.get('nbins_axis')
            if nbins_axis is None:
                raise ValueError("nbins_axis must be specified for GridPartition")
            try:
                parameters['nbins_axis'] = int(nbins_axis)
                if parameters['nbins_axis'] < 1:
                    raise ValueError
            except (TypeError, ValueError):
                raise ValueError("nbins_axis must be a positive integer")

        # Initialize and run the algorithm
        try:
            collector = algorithm_class(**parameters)
            indices = collector.select(arr_dist, size=size)

            # Ensure indices are valid
            if indices is None:
                raise ValueError("Algorithm returned None instead of indices")
            if len(indices) != size:
                warnings.warn(f"Algorithm returned {len(indices)} indices but expected {size}")

            # Convert indices to list and validate
            indices_list = indices.tolist() if isinstance(indices, np.ndarray) else list(indices)
            if not all(isinstance(i, (int, np.integer)) and 0 <= i < arr.shape[0] for i in indices_list):
                raise ValueError("Algorithm returned invalid indices")

            result["success"] = True
            result["indices"] = indices_list

        except Exception as e:
            import traceback
            print(f"Traceback: {traceback.format_exc()}")
            raise ValueError(f"Error executing algorithm: {str(e)}")

    except Warning as w:
        result["warnings"].append(str(w))
    except Exception as e:
        result["error"] = str(e)

    return result


@app.route("/upload_selection", methods=["POST"])
def upload_selection_file():
    """Handle file upload and process selection."""
    try:
        print("Debug - Starting upload_selection_file")

        if "file" not in request.files:
            return create_json_response({"error": "No file provided"}, 400)

        file = request.files["file"]
        if file.filename == "":
            return create_json_response({"error": "No file selected"}, 400)

        if not allowed_file(file.filename):
            return create_json_response({"error": "File type not allowed"}, 400)

        # Get parameters
        algorithm = request.form.get("algorithm")
        if not algorithm:
            return create_json_response({"error": "No algorithm specified"}, 400)

        # Get size parameter
        size = request.form.get("size")
        if not size:
            return create_json_response({"error": "Subset size must be specified"}, 400)

        # Get distance function
        dist_metric = request.form.get("func_dist", "")

        # Parse parameters
        try:
            parameters = orjson.loads(request.form.get("parameters", "{}"))
        except Exception as e:
            parameters = {}

        # Add size to parameters
        parameters["size"] = size

        # Create a unique directory for this upload
        upload_dir = get_unique_upload_dir()

        try:
            # Save file with unique name
            file_path = os.path.join(
                upload_dir, secure_filename(str(uuid.uuid4()) + "_" + file.filename)
            )

            with file_lock:
                file.save(file_path)
                # os.chmod(file_path, 0o666)  # Read/write for all

            # Load data
            array = load_data(file_path)

            # Process the selection with separate dist_metric parameter
            result = process_selection(array, algorithm, parameters, dist_metric)

            return create_json_response(result)

        except Exception as e:
            return create_json_response({"error": str(e)}, 500)

        finally:
            # Clean up the unique upload directory
            clean_upload_dir(upload_dir)

    except Exception as e:
        return create_json_response({"error": f"Error processing request: {str(e)}"}, 400)


@app.route("/download", methods=["POST"])
def download():
    """Download selected indices in specified format."""
    try:
        data = request.get_json()
        if not data or "indices" not in data:
            return create_json_response({"error": "No indices provided"}, 400)

        indices = data["indices"]
        format = data.get("format", "txt")
        timestamp = data.get("timestamp", datetime.now().strftime("%Y%m%d-%H%M%S"))

        # Create a BytesIO buffer for the file
        buffer = io.BytesIO()

        # Define format-specific settings
        format_settings = {
            "txt": {
                "extension": "txt",
                "mimetype": "text/plain",
                "processor": lambda b, d: b.write("\n".join(map(str, d)).encode()),
            },
            "npz": {
                "extension": "npz",
                "mimetype": "application/octet-stream",
                "processor": lambda b, d: np.savez_compressed(b, indices=np.array(d)),
            },
            "xlsx": {
                "extension": "xlsx",
                "mimetype": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
                "processor": lambda b, d: pd.DataFrame({"selected_indices": d}).to_excel(
                    b, index=False
                ),
            },
        }

        if format not in format_settings:
            return create_json_response({"error": f"Unsupported format: {format}"}, 400)

        settings = format_settings[format]

        # Process the file
        settings["processor"](buffer, indices)

        # Create filename with correct extension
        filename = f'selected_indices_{timestamp}.{settings["extension"]}'

        # Seek to beginning of file
        buffer.seek(0)

        return send_file(
            buffer, mimetype=settings["mimetype"], as_attachment=True, download_name=filename
        )

    except Exception as e:
        print(f"Error in download: {str(e)}")
        return create_json_response({"error": str(e)}, 500)


@app.route("/calculate_diversity", methods=["POST"])
def calculate_diversity():
    """Calculate diversity score for the given feature subset."""
    try:
        # Get files from request
        feature_subset_file = request.files.get('feature_subset')
        features_file = request.files.get('features')

        if not feature_subset_file:
            return create_json_response({"error": "Feature subset file is required"}, 400)

        # Get other parameters
        div_type = request.form.get('div_type', 'shannon_entropy')
        div_parameters = orjson.loads(request.form.get('div_parameters', '{}'))

        # Read feature subset
        try:
            # Save the uploaded file
            feature_subset_path = os.path.join(app.config['UPLOAD_FOLDER'], secure_filename(feature_subset_file.filename))
            feature_subset_file.save(feature_subset_path)

            # Read the feature subset file
            feature_subset = load_data(feature_subset_path)
            if feature_subset is None:
                raise ValueError(f"Failed to read feature subset file: {feature_subset_file.filename}")

            # Convert to float array
            feature_subset = feature_subset.astype(float)

            # Clean up the temporary file
            os.remove(feature_subset_path)
        except Exception as e:
            return create_json_response({"error": f"Error reading feature subset file: {str(e)}"}, 400)

        # Read features if provided
        features = None
        if features_file:
            try:
                # Save the uploaded file
                features_path = os.path.join(app.config['UPLOAD_FOLDER'], secure_filename(features_file.filename))
                features_file.save(features_path)

                # Read the features file
                features = load_data(features_path)
                if features is None:
                    raise ValueError(f"Failed to read features file: {features_file.filename}")

                # Convert to float array
                features = features.astype(float)

                # Clean up the temporary file
                os.remove(features_path)
            except Exception as e:
                return create_json_response({"error": f"Error reading features file: {str(e)}"}, 400)

        # Extract parameters
        normalize = div_parameters.get('normalize', False)
        truncation = div_parameters.get('truncation', False)
        cs = div_parameters.get('cs', None)

        # Calculate diversity
        try:
            diversity_score = compute_diversity(
                feature_subset=feature_subset,
                div_type=div_type,
                normalize=normalize,
                truncation=truncation,
                features=features,
                cs=cs
            )

            return create_json_response({
                "success": True,
                "diversity_score": float(diversity_score)
            })

        except Exception as e:
            import traceback
            print(f"Error calculating diversity: {str(e)}")
            print(f"Traceback: {traceback.format_exc()}")
            return create_json_response({"error": f"Error calculating diversity: {str(e)}"}, 400)

    except Exception as e:
        return create_json_response({"error": str(e)}, 500)

@app.route('/health')
def health_check():
    """Health check endpoint for Docker"""
    return create_json_response({"status": "healthy"})

if __name__ == "__main__":
    app.run(debug=False, host="0.0.0.0", port=7860)