import os
import json
import random
import pandas as pd
import numpy as np
from flask import Flask, render_template, request, jsonify
from datetime import datetime, timedelta

app = Flask(__name__)

# Default Configuration
app.config['MAX_CONTENT_LENGTH'] = 100 * 1024 * 1024  # 100MB limit

def process_dataframe(df):
    """Common logic to process dataframe and return RFM results."""
    # Validation
    # Normalize column names to be case-insensitive or handle variations
    df.columns = [c.strip() for c in df.columns]
    
    # Map common column names to required ones
    col_map = {
        '客户ID': 'CustomerID', 'customerid': 'CustomerID', 'customer_id': 'CustomerID',
        '订单日期': 'OrderDate', 'orderdate': 'OrderDate', 'order_date': 'OrderDate', 'date': 'OrderDate',
        '金额': 'Amount', 'amount': 'Amount', 'total': 'Amount'
    }
    df = df.rename(columns={c: col_map.get(c.lower(), c) for c in df.columns})

    required_cols = ['CustomerID', 'OrderDate', 'Amount']
    missing = [c for c in required_cols if c not in df.columns]
    if missing:
        raise ValueError(f"缺少必要列: {', '.join(missing)}。请确保包含 CustomerID(客户ID), OrderDate(订单日期), Amount(金额)。")

    # Run RFM
    return calculate_rfm(df)

@app.route('/api/upload', methods=['POST'])
def upload_file():
    try:
        if 'file' not in request.files:
            return jsonify({"error": "No file part"}), 400
        
        file = request.files['file']
        if file.filename == '':
            return jsonify({"error": "No selected file"}), 400
            
        if file and (file.filename.endswith('.csv') or file.filename.endswith('.txt')):
            try:
                df = pd.read_csv(file)
            except UnicodeDecodeError:
                # Try common encodings for Chinese users
                file.seek(0)
                df = pd.read_csv(file, encoding='gbk')
        elif file and (file.filename.endswith('.xlsx') or file.filename.endswith('.xls')):
            df = pd.read_excel(file)
        else:
            return jsonify({"error": "Unsupported file format. Please upload CSV or Excel."}), 400
            
        rfm_result = process_dataframe(df)
        
        # Statistics for Charts
        segment_counts = rfm_result['Segment'].value_counts().reset_index()
        segment_counts.columns = ['name', 'value']
        
        segment_monetary = rfm_result.groupby('Segment')['Monetary'].sum().reset_index()
        segment_monetary.columns = ['name', 'value']
        
        # Scatter Data
        scatter_data = []
        for segment in rfm_result['Segment'].unique():
            seg_df = rfm_result[rfm_result['Segment'] == segment]
            series_data = seg_df[['Recency', 'Frequency', 'Monetary', 'CustomerID', 'Segment']].values.tolist()
            scatter_data.append({
                "name": segment,
                "data": series_data
            })
            
        table_data = rfm_result.sort_values('Monetary', ascending=False).head(100).to_dict(orient='records')
        
        return jsonify({
            "segments_pie": segment_counts.to_dict(orient='records'),
            "segments_bar": segment_monetary.to_dict(orient='records'),
            "scatter_series": scatter_data,
            "table_data": table_data,
            "summary": {
                "total_customers": len(rfm_result),
                "total_revenue": float(rfm_result['Monetary'].sum()),
                "avg_order_value": float(df['Amount'].mean())
            }
        })
        
    except Exception as e:
        return jsonify({"error": str(e)}), 500

@app.route('/api/analyze', methods=['POST'])
def analyze():
    try:
        json_data = request.json
        if not json_data:
            return jsonify({"error": "No data provided"}), 400
            
        df = pd.DataFrame(json_data)
        
        # Use shared processing logic
        rfm_result = process_dataframe(df)
        
        # Statistics for Charts (Duplicate logic for now to keep it simple, or could refactor further)
        segment_counts = rfm_result['Segment'].value_counts().reset_index()
        segment_counts.columns = ['name', 'value']
        
        segment_monetary = rfm_result.groupby('Segment')['Monetary'].sum().reset_index()
        segment_monetary.columns = ['name', 'value']
        
        scatter_data = []
        for segment in rfm_result['Segment'].unique():
            seg_df = rfm_result[rfm_result['Segment'] == segment]
            series_data = seg_df[['Recency', 'Frequency', 'Monetary', 'CustomerID', 'Segment']].values.tolist()
            scatter_data.append({
                "name": segment,
                "data": series_data
            })
            
        table_data = rfm_result.sort_values('Monetary', ascending=False).head(100).to_dict(orient='records')
        
        return jsonify({
            "segments_pie": segment_counts.to_dict(orient='records'),
            "segments_bar": segment_monetary.to_dict(orient='records'),
            "scatter_series": scatter_data,
            "table_data": table_data,
            "summary": {
                "total_customers": len(rfm_result),
                "total_revenue": float(rfm_result['Monetary'].sum()),
                "avg_order_value": float(df['Amount'].mean())
            }
        })
        
    except Exception as e:
        return jsonify({"error": str(e)}), 500

def generate_demo_data(n=500):
    """Generate realistic e-commerce transaction data."""
    data = []
    end_date = datetime.now()
    customer_ids = [f"C{str(i).zfill(3)}" for i in range(1, 101)] # 100 customers
    
    for _ in range(n):
        cid = random.choice(customer_ids)
        # Random date within last 365 days
        days_offset = random.randint(0, 365)
        date = end_date - timedelta(days=days_offset)
        # Random amount with some outliers
        amount = round(random.uniform(10, 500) + (random.random() * 1000 if random.random() > 0.9 else 0), 2)
        
        data.append({
            "CustomerID": cid,
            "OrderDate": date.strftime("%Y-%m-%d"),
            "Amount": amount
        })
    return data

def calculate_rfm(df):
    """
    Calculate RFM metrics and segments.
    df columns: CustomerID, OrderDate, Amount
    """
    # Ensure date format
    df['OrderDate'] = pd.to_datetime(df['OrderDate'])
    
    # Reference date = max date + 1 day
    snapshot_date = df['OrderDate'].max() + timedelta(days=1)
    
    # Group by CustomerID
    rfm = df.groupby('CustomerID').agg({
        'OrderDate': lambda x: (snapshot_date - x.max()).days,
        'CustomerID': 'count',
        'Amount': 'sum'
    }).rename(columns={
        'OrderDate': 'Recency',
        'CustomerID': 'Frequency',
        'Amount': 'Monetary'
    })
    
    # Quintiles (1-5)
    # Recency: Lower is better (5), Higher is worse (1)
    # Frequency: Higher is better (5)
    # Monetary: Higher is better (5)
    
    # Handle small datasets where qcut might fail due to duplicate edges
    try:
        r_labels = range(5, 0, -1)
        f_labels = range(1, 6)
        m_labels = range(1, 6)
        
        rfm['R'] = pd.qcut(rfm['Recency'], q=5, labels=r_labels, duplicates='drop')
        rfm['F'] = pd.qcut(rfm['Frequency'], q=5, labels=f_labels, duplicates='drop')
        rfm['M'] = pd.qcut(rfm['Monetary'], q=5, labels=m_labels, duplicates='drop')
    except:
        # Fallback for very small data: simple ranking
        rfm['R'] = 3
        rfm['F'] = 3
        rfm['M'] = 3
        
    # Cast to int
    rfm['R'] = rfm['R'].astype(int)
    rfm['F'] = rfm['F'].astype(int)
    rfm['M'] = rfm['M'].astype(int)
    
    rfm['RFM_Score'] = rfm['R'].astype(str) + rfm['F'].astype(str) + rfm['M'].astype(str)
    
    # Segment Logic
    def segment_customer(row):
        r, f, m = row['R'], row['F'], row['M']
        avg_fm = (f + m) / 2
        
        if r >= 5 and avg_fm >= 5:
            return "Champions (至尊王者)"
        elif r >= 3 and avg_fm >= 4:
            return "Loyal Customers (忠诚客户)"
        elif r >= 4 and avg_fm >= 2:
            return "Potential Loyalist (潜力股)"
        elif r >= 5 and avg_fm == 1:
            return "New Customers (新客)"
        elif r >= 3 and avg_fm <= 2:
            return "Promising (这就去买)"
        elif r <= 2 and avg_fm >= 4:
            return "At Risk (流失预警)"
        elif r <= 2 and avg_fm >= 2:
            return "Hibernating (沉睡客户)"
        else:
            return "Lost (已流失)"

    rfm['Segment'] = rfm.apply(segment_customer, axis=1)
    
    # Prepare for JSON
    rfm['CustomerID'] = rfm.index
    result = rfm.reset_index(drop=True)
    
    return result

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

@app.route('/api/demo-data', methods=['GET'])
def get_demo_data():
    data = generate_demo_data()
    return jsonify(data)

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