src/streamlit_app.py

import streamlit as st
import pandas as pd
import plotly.graph_objects as go
import plotly.express as px
import json
import os
from datetime import datetime

# 页面配置（必须在最开始）
st.set_page_config(
    page_title="溶剂分数转换器",
    page_icon="🧪",
    layout="wide",
    initial_sidebar_state="expanded"
)

# 访问统计功能
def manage_visit_stats():
    """管理访问统计"""
    stats_file = "visit_stats.json"
    
    # 初始化统计数据
    if os.path.exists(stats_file):
        try:
            with open(stats_file, 'r', encoding='utf-8') as f:
                stats = json.load(f)
        except:
            stats = {
                "total_visits": 0,
                "daily_visits": {},
                "first_visit": datetime.now().strftime("%Y-%m-%d %H:%M:%S"),
                "last_visit": None
            }
    else:
        stats = {
            "total_visits": 0,
            "daily_visits": {},
            "first_visit": datetime.now().strftime("%Y-%m-%d %H:%M:%S"),
            "last_visit": None
        }
    
    # 检查是否需要更新统计
    if 'visit_counted' not in st.session_state:
        st.session_state.visit_counted = True
        
        # 更新统计
        today = datetime.now().strftime("%Y-%m-%d")
        stats["total_visits"] += 1
        stats["daily_visits"][today] = stats["daily_visits"].get(today, 0) + 1
        stats["last_visit"] = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
        
        # 保存统计
        try:
            with open(stats_file, 'w', encoding='utf-8') as f:
                json.dump(stats, f, ensure_ascii=False, indent=2)
        except:
            pass  # 忽略写入错误
    
    return stats

# 在页面配置后调用
visit_stats = manage_visit_stats()

# 自定义CSS样式
st.markdown("""
<style>
    /* 主标题样式 */
    .main-title {
        font-size: 2.5rem;
        font-weight: bold;
        text-align: center;
        background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
        -webkit-background-clip: text;
        -webkit-text-fill-color: transparent;
        margin-bottom: 2rem;
    }
    
    /* 卡片样式 */
    .metric-card {
        background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        padding: 1rem;
        border-radius: 10px;
        color: white;
        box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
        margin-bottom: 1rem;
    }
    
    /* 侧边栏样式 */
    .sidebar .sidebar-content {
        background: linear-gradient(180deg, #667eea 0%, #764ba2 100%);
    }
    
    /* 公式框样式 */
    .formula-box {
        background: #f8f9fa;
        border: 2px solid #e9ecef;
        border-radius: 10px;
        padding: 1.5rem;
        margin: 1rem 0;
        box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    }
    
    /* 信息框样式 */
    .info-box {
        background: linear-gradient(135deg, #74b9ff 0%, #0984e3 100%);
        color: white;
        padding: 1rem;
        border-radius: 10px;
        margin: 1rem 0;
    }
    
    /* 警告框样式 */
    .warning-box {
        background: linear-gradient(135deg, #fd79a8 0%, #e84393 100%);
        color: white;
        padding: 1rem;
        border-radius: 10px;
        margin: 1rem 0;
    }
    
    /* 数据表格样式 */
    .dataframe {
        border-radius: 10px;
        overflow: hidden;
        box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    }
    
    /* 访问统计样式 */
    .visit-stats {
        background: linear-gradient(135deg, #00b894 0%, #00a085 100%);
        color: white;
        padding: 1rem;
        border-radius: 10px;
        margin: 1rem 0;
        text-align: center;
    }
</style>
""", unsafe_allow_html=True)

# 语言配置
LANGUAGES = {
    "中文": {
        "page_title": "溶剂分数转换器",
        "main_title": "🧪 溶剂摩尔分数、体积分数与质量分数转换器",
        "conversion_mode": "🔄 转换模式",
        "mode_mole_to_vol": "摩尔分数 → 体积分数",
        "mode_vol_to_mole": "体积分数 → 摩尔分数",
        "mode_mole_to_mass": "摩尔分数 → 质量分数",
        "mode_mass_to_mole": "质量分数 → 摩尔分数",
        "mode_vol_to_mass": "体积分数 → 质量分数",
        "mode_mass_to_vol": "质量分数 → 体积分数",
        "select_conversion": "选择转换方向:",
        "solvent_selection": "🧫 溶剂选择",
        "select_solvents": "选择两种溶剂或自定义参数:",
        "solvent_a": "溶剂A:",
        "solvent_b": "溶剂B:",
        "custom": "🛠️ 自定义",
        "molar_mass": "摩尔质量",
        "density": "密度",
        "input_mole_fraction": "📥 输入摩尔分数",
        "input_volume_fraction": "📥 输入体积分数",
        "input_mass_fraction": "📥 输入质量分数",
        "mole_fraction_of": "摩尔分数",
        "volume_fraction_of": "体积分数",
        "mass_fraction_of": "质量分数",
        "result_volume_fraction": "📊 计算结果 - 体积分数",
        "result_mole_fraction": "📊 计算结果 - 摩尔分数",
        "result_mass_fraction": "📊 计算结果 - 质量分数",
        "verification": "✅ 验证",
        "detailed_info": "📋 详细信息",
        "solvent_params": "🔬 溶剂参数",
        "solvent": "溶剂",
        "mole_fraction": "摩尔分数",
        "volume_fraction": "体积分数",
        "mass_fraction": "质量分数",
        "mole_verification": "摩尔分数验证",
        "volume_verification": "体积分数验证", 
        "mass_verification": "质量分数验证",
        "fraction_visualization": "溶剂分数可视化",
        "mole_fraction_chart": "摩尔分数",
        "volume_fraction_chart": "体积分数",
        "mass_fraction_chart": "质量分数",
        "calculation_formula": "📐 计算公式",
        "formula_mole_to_vol_title": "**摩尔分数转换为体积分数:**",
        "formula_vol_to_mole_title": "**体积分数转换为摩尔分数:**",
        "formula_mole_to_mass_title": "**摩尔分数转换为质量分数:**",
        "formula_mass_to_mole_title": "**质量分数转换为摩尔分数:**",
        "formula_vol_to_mass_title": "**体积分数转换为质量分数:**",
        "formula_mass_to_vol_title": "**质量分数转换为体积分数:**",
        "formula_where": "其中:",
        "usage_instructions": "📖 使用说明",
        "instruction_1": "1. **选择转换模式**: 在侧边栏选择转换方向",
        "instruction_2": "2. **选择溶剂**: 从预设的常见溶剂中选择，或选择\"自定义\"输入参数",
        "instruction_3": "3. **输入数值**: 输入摩尔分数、体积分数或质量分数",
        "instruction_4": "4. **查看结果**: 右侧显示转换结果和详细信息",
        "note": "⚠️ **注意**: 本计算假设理想混合，实际情况可能存在偏差。",
        "language": "🌐 语言",
        "visualization": "📈 可视化",
        "visit_stats": "📊 访问统计",
        "total_visits": "总访问量",
        "today_visits": "今日访问",
        "last_visit": "上次访问",
        "visit_trend": "访问趋势",
        "recent_days": "最近访问趋势",
        "date": "日期",
        "visits": "访问次数"
    },
    "English": {
        "page_title": "Solvent Fraction Converter",
        "main_title": "🧪 Solvent Mole Fraction, Volume Fraction & Mass Fraction Converter",
        "conversion_mode": "🔄 Conversion Mode",
        "mode_mole_to_vol": "Mole Fraction → Volume Fraction",
        "mode_vol_to_mole": "Volume Fraction → Mole Fraction",
        "mode_mole_to_mass": "Mole Fraction → Mass Fraction",
        "mode_mass_to_mole": "Mass Fraction → Mole Fraction",
        "mode_vol_to_mass": "Volume Fraction → Mass Fraction",
        "mode_mass_to_vol": "Mass Fraction → Volume Fraction",
        "select_conversion": "Select conversion direction:",
        "solvent_selection": "🧫 Solvent Selection",
        "select_solvents": "Select two solvents or customize parameters:",
        "solvent_a": "Solvent A:",
        "solvent_b": "Solvent B:",
        "custom": "🛠️ Custom",
        "molar_mass": "Molar Mass",
        "density": "Density",
        "input_mole_fraction": "📥 Input Mole Fraction",
        "input_volume_fraction": "📥 Input Volume Fraction",
        "input_mass_fraction": "📥 Input Mass Fraction",
        "mole_fraction_of": "Mole fraction of",
        "volume_fraction_of": "Volume fraction of",
        "mass_fraction_of": "Mass fraction of",
        "result_volume_fraction": "📊 Results - Volume Fraction",
        "result_mole_fraction": "📊 Results - Mole Fraction",
        "result_mass_fraction": "📊 Results - Mass Fraction",
        "verification": "✅ Verification",
        "detailed_info": "📋 Detailed Information",
        "solvent_params": "🔬 Solvent Parameters",
        "solvent": "Solvent",
        "mole_fraction": "Mole Fraction",
        "volume_fraction": "Volume Fraction",
        "mass_fraction": "Mass Fraction",
        "mole_verification": "Mole Fraction Verification",
        "volume_verification": "Volume Fraction Verification",
        "mass_verification": "Mass Fraction Verification", 
        "fraction_visualization": "Solvent Fraction Visualization",
        "mole_fraction_chart": "Mole Fraction",
        "volume_fraction_chart": "Volume Fraction",
        "mass_fraction_chart": "Mass Fraction",
        "calculation_formula": "📐 Calculation Formula",
        "formula_mole_to_vol_title": "**Mole Fraction to Volume Fraction:**",
        "formula_vol_to_mole_title": "**Volume Fraction to Mole Fraction:**",
        "formula_mole_to_mass_title": "**Mole Fraction to Mass Fraction:**",
        "formula_mass_to_mole_title": "**Mass Fraction to Mole Fraction:**",
        "formula_vol_to_mass_title": "**Volume Fraction to Mass Fraction:**",
        "formula_mass_to_vol_title": "**Mass Fraction to Volume Fraction:**",
        "formula_where": "Where:",
        "usage_instructions": "📖 Usage Instructions",
        "instruction_1": "1. **Select Conversion Mode**: Choose conversion direction in sidebar",
        "instruction_2": "2. **Select Solvents**: Choose from preset common solvents or select 'Custom' to input parameters",
        "instruction_3": "3. **Input Values**: Input mole fraction, volume fraction or mass fraction",
        "instruction_4": "4. **View Results**: Results and detailed information are displayed on the right",
        "note": "⚠️ **Note**: This calculation assumes ideal mixing; actual situations may deviate.",
        "language": "🌐 Language",
        "visualization": "📈 Visualization",
        "visit_stats": "📊 Visit Statistics",
        "total_visits": "Total Visits",
        "today_visits": "Today's Visits",
        "last_visit": "Last Visit",
        "visit_trend": "Visit Trend",
        "recent_days": "Recent Visit Trend",
        "date": "Date",
        "visits": "Visits"
    }
}

# 常见溶剂的摩尔质量和密度数据库
SOLVENTS_DB = {
    "中文": {
        "水": {"M": 18.02, "density": 1.000, "en": "Water", "color": "#3498db"},
        "乙醇": {"M": 46.07, "density": 0.789, "en": "Ethanol", "color": "#e74c3c"},
        "甲醇": {"M": 32.04, "density": 0.792, "en": "Methanol", "color": "#9b59b6"},
        "异丙醇": {"M": 60.10, "density": 0.786, "en": "Isopropanol", "color": "#f39c12"},
        "丙酮": {"M": 58.08, "density": 0.784, "en": "Acetone", "color": "#2ecc71"},
        "乙酸乙酯": {"M": 88.11, "density": 0.902, "en": "Ethyl Acetate", "color": "#1abc9c"},
        "甲苯": {"M": 92.14, "density": 0.867, "en": "Toluene", "color": "#34495e"},
        "二氯甲烷": {"M": 84.93, "density": 1.326, "en": "Dichloromethane", "color": "#e67e22"},
        "氯仿": {"M": 119.38, "density": 1.489, "en": "Chloroform", "color": "#95a5a6"},
        "四氢呋喃": {"M": 72.11, "density": 0.889, "en": "Tetrahydrofuran", "color": "#8e44ad"},
        "二甲基亚砜": {"M": 78.13, "density": 1.100, "en": "Dimethyl Sulfoxide", "color": "#27ae60"},
        "N,N-二甲基甲酰胺": {"M": 73.09, "density": 0.944, "en": "N,N-Dimethylformamide", "color": "#16a085"},
        "乙腈": {"M": 41.05, "density": 0.786, "en": "Acetonitrile", "color": "#2980b9"},
        "正己烷": {"M": 86.18, "density": 0.659, "en": "n-Hexane", "color": "#d35400"},
        "环己烷": {"M": 84.16, "density": 0.779, "en": "Cyclohexane", "color": "#7f8c8d"},
        "苯": {"M": 78.11, "density": 0.876, "en": "Benzene", "color": "#c0392b"},
        "乙二醇": {"M": 62.07, "density": 1.113, "en": "Ethylene Glycol", "color": "#8e44ad"},
        "甘油": {"M": 92.09, "density": 1.261, "en": "Glycerol", "color": "#f1c40f"}
    },
    "English": {
        "Water": {"M": 18.02, "density": 1.000, "cn": "水", "color": "#3498db"},
        "Ethanol": {"M": 46.07, "density": 0.789, "cn": "乙醇", "color": "#e74c3c"},
        "Methanol": {"M": 32.04, "density": 0.792, "cn": "甲醇", "color": "#9b59b6"},
        "Isopropanol": {"M": 60.10, "density": 0.786, "cn": "异丙醇", "color": "#f39c12"},
        "Acetone": {"M": 58.08, "density": 0.784, "cn": "丙酮", "color": "#2ecc71"},
        "Ethyl Acetate": {"M": 88.11, "density": 0.902, "cn": "乙酸乙酯", "color": "#1abc9c"},
        "Toluene": {"M": 92.14, "density": 0.867, "cn": "甲苯", "color": "#34495e"},
        "Dichloromethane": {"M": 84.93, "density": 1.326, "cn": "二氯甲烷", "color": "#e67e22"},
        "Chloroform": {"M": 119.38, "density": 1.489, "cn": "氯仿", "color": "#95a5a6"},
        "Tetrahydrofuran": {"M": 72.11, "density": 0.889, "cn": "四氢呋喃", "color": "#8e44ad"},
        "Dimethyl Sulfoxide": {"M": 78.13, "density": 1.100, "cn": "二甲基亚砜", "color": "#27ae60"},
        "N,N-Dimethylformamide": {"M": 73.09, "density": 0.944, "cn": "N,N-二甲基甲酰胺", "color": "#16a085"},
        "Acetonitrile": {"M": 41.05, "density": 0.786, "cn": "乙腈", "color": "#2980b9"},
        "n-Hexane": {"M": 86.18, "density": 0.659, "cn": "正己烷", "color": "#d35400"},
        "Cyclohexane": {"M": 84.16, "density": 0.779, "cn": "环己烷", "color": "#7f8c8d"},
        "Benzene": {"M": 78.11, "density": 0.876, "cn": "苯", "color": "#c0392b"},
        "Ethylene Glycol": {"M": 62.07, "density": 1.113, "cn": "乙二醇", "color": "#8e44ad"},
        "Glycerol": {"M": 92.09, "density": 1.261, "cn": "甘油", "color": "#f1c40f"}
    }
}

# 语言选择
language = st.sidebar.selectbox(
    "🌐 Language/语言:", 
    ["English", "中文"],
    help="Choose your preferred language / 选择您的首选语言"
)
lang = LANGUAGES[language]

# 主标题
st.markdown(f'<h1 class="main-title">{lang["main_title"]}</h1>', unsafe_allow_html=True)

# 添加分隔线
st.markdown("""
<div style="height: 2px; background: linear-gradient(90deg, #667eea 0%, #764ba2 100%); margin: 2rem 0;"></div>
""", unsafe_allow_html=True)

# 侧边栏配置
with st.sidebar:
    st.markdown("### " + lang["conversion_mode"])
    conversion_mode = st.radio(
        "",
        [lang["mode_mole_to_vol"], lang["mode_vol_to_mole"], 
         lang["mode_mole_to_mass"], lang["mode_mass_to_mole"],
         lang["mode_vol_to_mass"], lang["mode_mass_to_vol"]],
        help="选择您需要的转换方向"
    )
    
    st.markdown("---")
    st.markdown("### " + lang["solvent_selection"])
    
    # 获取当前语言的溶剂列表
    current_solvents = SOLVENTS_DB[language]
    solvent_names = list(current_solvents.keys()) + [lang["custom"]]
    
    # 溶剂A选择
    solvent_a_name = st.selectbox(
        lang["solvent_a"], 
        solvent_names,
        help="选择第一种溶剂"
    )
    
    if solvent_a_name == lang["custom"]:
        col1, col2 = st.columns(2)
        with col1:
            M_a = st.number_input(f"{lang['molar_mass']} A (g/mol):", value=18.02, min_value=0.1, step=0.01)
        with col2:
            rho_a = st.number_input(f"{lang['density']} A (g/cm³):", value=1.000, min_value=0.1, step=0.001)
    else:
        M_a = current_solvents[solvent_a_name]["M"]
        rho_a = current_solvents[solvent_a_name]["density"]
        st.info(f"📊 {lang['molar_mass']}: **{M_a}** g/mol  \n📊 {lang['density']}: **{rho_a}** g/cm³")
    
    # 溶剂B选择
    solvent_b_name = st.selectbox(
        lang["solvent_b"], 
        solvent_names,
        help="选择第二种溶剂"
    )
    
    if solvent_b_name == lang["custom"]:
        col1, col2 = st.columns(2)
        with col1:
            M_b = st.number_input(f"{lang['molar_mass']} B (g/mol):", value=46.07, min_value=0.1, step=0.01)
        with col2:
            rho_b = st.number_input(f"{lang['density']} B (g/cm³):", value=0.789, min_value=0.1, step=0.001)
    else:
        M_b = current_solvents[solvent_b_name]["M"]
        rho_b = current_solvents[solvent_b_name]["density"]
        st.info(f"📊 {lang['molar_mass']}: **{M_b}** g/mol  \n📊 {lang['density']}: **{rho_b}** g/cm³")

    # 访问统计显示
    st.markdown("---")
    st.markdown("### " + lang["visit_stats"])
    
    # 显示统计信息
    col1, col2 = st.columns(2)
    with col1:
        st.metric(lang["total_visits"], visit_stats["total_visits"])
    with col2:
        today = datetime.now().strftime("%Y-%m-%d")
        today_visits = visit_stats["daily_visits"].get(today, 0)
        st.metric(lang["today_visits"], today_visits)
    
    # 显示最近访问时间
    if visit_stats["last_visit"]:
        st.caption(f"{lang['last_visit']}: {visit_stats['last_visit']}")
    
    # 显示访问趋势（简单的条形图）
    if len(visit_stats["daily_visits"]) > 1:
        recent_days = list(visit_stats["daily_visits"].items())[-7:]  # 最近7天
        dates = [item[0] for item in recent_days]
        counts = [item[1] for item in recent_days]
        
        if len(dates) > 1:
            df_visits = pd.DataFrame({
                lang["date"]: dates,
                lang["visits"]: counts
            })
            fig_visits = px.bar(
                df_visits, 
                x=lang["date"], 
                y=lang["visits"], 
                title=lang["recent_days"],
                height=200,
                color=lang["visits"],
                color_continuous_scale="viridis"
            )
            fig_visits.update_layout(
                showlegend=False,
                margin=dict(l=20, r=20, t=40, b=20),
                xaxis_title="",
                yaxis_title="",
                font=dict(size=10)
            )
            st.plotly_chart(fig_visits, use_container_width=True)

# 主界面内容
col1, col2 = st.columns([1, 1], gap="large")

# 定义计算函数
def calculate_conversion(mode, input_val, M_a, M_b, rho_a, rho_b):
    """计算转换结果"""
    if mode == lang["mode_mole_to_vol"]:
        x_a, x_b = input_val, 1.0 - input_val
        V_ratio_a = x_a * M_a / rho_a
        V_ratio_b = x_b * M_b / rho_b
        V_total = V_ratio_a + V_ratio_b
        if V_total > 0:
            phi_a = V_ratio_a / V_total
            phi_b = V_ratio_b / V_total
        else:
            phi_a = phi_b = 0
        return (x_a, x_b), (phi_a, phi_b), None
    
    elif mode == lang["mode_vol_to_mole"]:
        phi_a, phi_b = input_val, 1.0 - input_val
        n_ratio_a = phi_a * rho_a / M_a
        n_ratio_b = phi_b * rho_b / M_b
        n_total = n_ratio_a + n_ratio_b
        if n_total > 0:
            x_a = n_ratio_a / n_total
            x_b = n_ratio_b / n_total
        else:
            x_a = x_b = 0
        return (x_a, x_b), (phi_a, phi_b), None
    
    elif mode == lang["mode_mole_to_mass"]:
        x_a, x_b = input_val, 1.0 - input_val
        mass_a = x_a * M_a
        mass_b = x_b * M_b
        mass_total = mass_a + mass_b
        if mass_total > 0:
            w_a = mass_a / mass_total
            w_b = mass_b / mass_total
        else:
            w_a = w_b = 0
        return (x_a, x_b), None, (w_a, w_b)
    
    elif mode == lang["mode_mass_to_mole"]:
        w_a, w_b = input_val, 1.0 - input_val
        n_ratio_a = w_a / M_a
        n_ratio_b = w_b / M_b
        n_total = n_ratio_a + n_ratio_b
        if n_total > 0:
            x_a = n_ratio_a / n_total
            x_b = n_ratio_b / n_total
        else:
            x_a = x_b = 0
        return (x_a, x_b), None, (w_a, w_b)
    
    elif mode == lang["mode_vol_to_mass"]:
        phi_a, phi_b = input_val, 1.0 - input_val
        mass_a = phi_a * rho_a
        mass_b = phi_b * rho_b
        mass_total = mass_a + mass_b
        if mass_total > 0:
            w_a = mass_a / mass_total
            w_b = mass_b / mass_total
        else:
            w_a = w_b = 0
        return None, (phi_a, phi_b), (w_a, w_b)
    
    elif mode == lang["mode_mass_to_vol"]:
        w_a, w_b = input_val, 1.0 - input_val
        vol_a = w_a / rho_a
        vol_b = w_b / rho_b
        vol_total = vol_a + vol_b
        if vol_total > 0:
            phi_a = vol_a / vol_total
            phi_b = vol_b / vol_total
        else:
            phi_a = phi_b = 0
        return None, (phi_a, phi_b), (w_a, w_b)

# 输入区域
with col1:
    # 初始化 input_val 默认值
    input_val = 0.5
    
    if conversion_mode in [lang["mode_mole_to_vol"], lang["mode_mole_to_mass"]]:
        st.markdown(f"### {lang['input_mole_fraction']}")
        input_val = st.number_input(
            f"{lang['mole_fraction_of']} {solvent_a_name} (x_A):",
            min_value=0.0,
            max_value=1.0,
            value=0.5,
            step=0.001,
            format="%.4f",
            help="输入溶剂A的摩尔分数"
        )
        complement_val = 1.0 - input_val
        st.metric(
            f"{lang['mole_fraction_of']} {solvent_b_name} (x_B)",
            f"{complement_val:.4f}",
            help="溶剂B的摩尔分数（自动计算）"
        )
    
    elif conversion_mode in [lang["mode_vol_to_mole"], lang["mode_vol_to_mass"]]:
        st.markdown(f"### {lang['input_volume_fraction']}")
        input_val = st.number_input(
            f"{lang['volume_fraction_of']} {solvent_a_name} (φ_A):",
            min_value=0.0,
            max_value=1.0,
            value=0.5,
            step=0.001,
            format="%.4f",
            help="输入溶剂A的体积分数"
        )
        complement_val = 1.0 - input_val
        st.metric(
            f"{lang['volume_fraction_of']} {solvent_b_name} (φ_B)",
            f"{complement_val:.4f}",
            help="溶剂B的体积分数（自动计算）"
        )
    
    elif conversion_mode in [lang["mode_mass_to_mole"], lang["mode_mass_to_vol"]]:
        st.markdown(f"### {lang['input_mass_fraction']}")
        input_val = st.number_input(
            f"{lang['mass_fraction_of']} {solvent_a_name} (w_A):",
            min_value=0.0,
            max_value=1.0,
            value=0.5,
            step=0.001,
            format="%.4f",
            help="输入溶剂A的质量分数"
        )
        complement_val = 1.0 - input_val
        st.metric(
            f"{lang['mass_fraction_of']} {solvent_b_name} (w_B)",
            f"{complement_val:.4f}",
            help="溶剂B的质量分数（自动计算）"
        )

# 计算结果
mole_result, vol_result, mass_result = calculate_conversion(
    conversion_mode, input_val, M_a, M_b, rho_a, rho_b
)

# 结果显示区域
with col2:
    if conversion_mode == lang["mode_mole_to_vol"]:
        st.markdown(f"### {lang['result_volume_fraction']}")
        col2_1, col2_2 = st.columns(2)
        with col2_1:
            st.metric(
                f"φ_A ({solvent_a_name})",
                f"{vol_result[0]:.4f}",
                delta=f"{vol_result[0] - mole_result[0]:.4f}",
                help="溶剂A的体积分数"
            )
        with col2_2:
            st.metric(
                f"φ_B ({solvent_b_name})",
                f"{vol_result[1]:.4f}",
                delta=f"{vol_result[1] - mole_result[1]:.4f}",
                help="溶剂B的体积分数"
            )
    
    elif conversion_mode == lang["mode_vol_to_mole"]:
        st.markdown(f"### {lang['result_mole_fraction']}")
        col2_1, col2_2 = st.columns(2)
        with col2_1:
            st.metric(
                f"x_A ({solvent_a_name})",
                f"{mole_result[0]:.4f}",
                delta=f"{mole_result[0] - vol_result[0]:.4f}",
                help="溶剂A的摩尔分数"
            )
        with col2_2:
            st.metric(
                f"x_B ({solvent_b_name})",
                f"{mole_result[1]:.4f}",
                delta=f"{mole_result[1] - vol_result[1]:.4f}",
                help="溶剂B的摩尔分数"
            )
    
    elif conversion_mode == lang["mode_mole_to_mass"]:
        st.markdown(f"### {lang['result_mass_fraction']}")
        col2_1, col2_2 = st.columns(2)
        with col2_1:
            st.metric(
                f"w_A ({solvent_a_name})",
                f"{mass_result[0]:.4f}",
                delta=f"{mass_result[0] - mole_result[0]:.4f}",
                help="溶剂A的质量分数"
            )
        with col2_2:
            st.metric(
                f"w_B ({solvent_b_name})",
                f"{mass_result[1]:.4f}",
                delta=f"{mass_result[1] - mole_result[1]:.4f}",
                help="溶剂B的质量分数"
            )
    
    elif conversion_mode == lang["mode_mass_to_mole"]:
        st.markdown(f"### {lang['result_mole_fraction']}")
        col2_1, col2_2 = st.columns(2)
        with col2_1:
            st.metric(
                f"x_A ({solvent_a_name})",
                f"{mole_result[0]:.4f}",
                delta=f"{mole_result[0] - mass_result[0]:.4f}",
                help="溶剂A的摩尔分数"
            )
        with col2_2:
            st.metric(
                f"x_B ({solvent_b_name})",
                f"{mole_result[1]:.4f}",
                delta=f"{mole_result[1] - mass_result[1]:.4f}",
                help="溶剂B的摩尔分数"
            )
    
    elif conversion_mode == lang["mode_vol_to_mass"]:
        st.markdown(f"### {lang['result_mass_fraction']}")
        col2_1, col2_2 = st.columns(2)
        with col2_1:
            st.metric(
                f"w_A ({solvent_a_name})",
                f"{mass_result[0]:.4f}",
                delta=f"{mass_result[0] - vol_result[0]:.4f}",
                help="溶剂A的质量分数"
            )
        with col2_2:
            st.metric(
                f"w_B ({solvent_b_name})",
                f"{mass_result[1]:.4f}",
                delta=f"{mass_result[1] - vol_result[1]:.4f}",
                help="溶剂B的质量分数"
            )
    
    elif conversion_mode == lang["mode_mass_to_vol"]:
        st.markdown(f"### {lang['result_volume_fraction']}")
        col2_1, col2_2 = st.columns(2)
        with col2_1:
            st.metric(
                f"φ_A ({solvent_a_name})",
                f"{vol_result[0]:.4f}",
                delta=f"{vol_result[0] - mass_result[0]:.4f}",
                help="溶剂A的体积分数"
            )
        with col2_2:
            st.metric(
                f"φ_B ({solvent_b_name})",
                f"{vol_result[1]:.4f}",
                delta=f"{vol_result[1] - mass_result[1]:.4f}",
                help="溶剂B的体积分数"
            )
    
    # 验证信息
    st.markdown("---")
    if mole_result:
        st.success(f"✅ {lang['mole_verification']}: {mole_result[0] + mole_result[1]:.6f}")
    if vol_result:
        st.success(f"✅ {lang['volume_verification']}: {vol_result[0] + vol_result[1]:.6f}")
    if mass_result:
        st.success(f"✅ {lang['mass_verification']}: {mass_result[0] + mass_result[1]:.6f}")

# 可视化部分修改
st.markdown("---")
st.markdown(f"### {lang['visualization']}")

# 创建饼图
fig = go.Figure()

if mole_result:
    fig.add_trace(go.Pie(
        labels=[solvent_a_name, solvent_b_name],
        values=[mole_result[0], mole_result[1]],
        name=lang["mole_fraction_chart"],
        domain=dict(x=[0, 0.3]),
        title=lang["mole_fraction_chart"],
        marker_colors=[current_solvents.get(solvent_a_name, {}).get('color', '#3498db'),
                      current_solvents.get(solvent_b_name, {}).get('color', '#e74c3c')]
    ))

if vol_result:
    fig.add_trace(go.Pie(
        labels=[solvent_a_name, solvent_b_name],
        values=[vol_result[0], vol_result[1]],
        name=lang["volume_fraction_chart"],
        domain=dict(x=[0.35, 0.65]),
        title=lang["volume_fraction_chart"],
        marker_colors=[current_solvents.get(solvent_a_name, {}).get('color', '#3498db'),
                      current_solvents.get(solvent_b_name, {}).get('color', '#e74c3c')]
    ))

if mass_result:
    fig.add_trace(go.Pie(
        labels=[solvent_a_name, solvent_b_name],
        values=[mass_result[0], mass_result[1]],
        name=lang["mass_fraction_chart"],
        domain=dict(x=[0.7, 1.0]),
        title=lang["mass_fraction_chart"],
        marker_colors=[current_solvents.get(solvent_a_name, {}).get('color', '#3498db'),
                      current_solvents.get(solvent_b_name, {}).get('color', '#e74c3c')]
    ))

fig.update_traces(textposition='inside', textinfo='percent+label')
fig.update_layout(
    title_text=lang["fraction_visualization"],
    showlegend=False,
    height=400,
    margin=dict(l=20, r=20, t=50, b=20)
)

st.plotly_chart(fig, use_container_width=True)

# 详细信息表格
st.markdown("---")
st.markdown(f"### {lang['detailed_info']}")

col1, col2, col3 = st.columns(3)

with col1:
    st.markdown(f"#### {lang['solvent_params']}")
    df_params = pd.DataFrame({
        lang["solvent"]: [solvent_a_name, solvent_b_name],
        f"{lang['molar_mass']} (g/mol)": [M_a, M_b],
        f"{lang['density']} (g/cm³)": [rho_a, rho_b]
    })
    st.dataframe(df_params, use_container_width=True)

with col2:
    if mole_result:
        st.markdown(f"#### {lang['mole_fraction']}")
        df_mole = pd.DataFrame({
            lang["solvent"]: [solvent_a_name, solvent_b_name],
            lang["mole_fraction"]: [f"{mole_result[0]:.4f}", f"{mole_result[1]:.4f}"]
        })
        st.dataframe(df_mole, use_container_width=True)
    
    if vol_result:
        st.markdown(f"#### {lang['volume_fraction']}")
        df_vol = pd.DataFrame({
            lang["solvent"]: [solvent_a_name, solvent_b_name],
            lang["volume_fraction"]: [f"{vol_result[0]:.4f}", f"{vol_result[1]:.4f}"]
        })
        st.dataframe(df_vol, use_container_width=True)

with col3:
    if mass_result:
        st.markdown(f"#### {lang['mass_fraction']}")
        df_mass = pd.DataFrame({
            lang["solvent"]: [solvent_a_name, solvent_b_name],
            lang["mass_fraction"]: [f"{mass_result[0]:.4f}", f"{mass_result[1]:.4f}"]
        })
        st.dataframe(df_mass, use_container_width=True)

# 公式说明（在可折叠容器中）
with st.expander(f"📐 {lang['calculation_formula']}", expanded=False):
    formula_dict = {
        lang["mode_mole_to_vol"]: {
            "formula": r"\phi_A = \frac{x_A \cdot M_A / \rho_A}{x_A \cdot M_A / \rho_A + x_B \cdot M_B / \rho_B}",
            "vars": "x_A, x_B: 摩尔分数; φ_A, φ_B: 体积分数; M_A, M_B: 摩尔质量 (g/mol); ρ_A, ρ_B: 密度 (g/cm³)"
        },
        lang["mode_vol_to_mole"]: {
            "formula": r"x_A = \frac{\phi_A \cdot \rho_A / M_A}{\phi_A \cdot \rho_A / M_A + \phi_B \cdot \rho_B / M_B}",
            "vars": "φ_A, φ_B: 体积分数; x_A, x_B: 摩尔分数; M_A, M_B: 摩尔质量 (g/mol); ρ_A, ρ_B: 密度 (g/cm³)"
        },
        lang["mode_mole_to_mass"]: {
            "formula": r"w_A = \frac{x_A \cdot M_A}{x_A \cdot M_A + x_B \cdot M_B}",
            "vars": "x_A, x_B: 摩尔分数; w_A, w_B: 质量分数; M_A, M_B: 摩尔质量 (g/mol)"
        },
        lang["mode_mass_to_mole"]: {
            "formula": r"x_A = \frac{w_A / M_A}{w_A / M_A + w_B / M_B}",
            "vars": "w_A, w_B: 质量分数; x_A, x_B: 摩尔分数; M_A, M_B: 摩尔质量 (g/mol)"
        },
        lang["mode_vol_to_mass"]: {
            "formula": r"w_A = \frac{\phi_A \cdot \rho_A}{\phi_A \cdot \rho_A + \phi_B \cdot \rho_B}",
            "vars": "φ_A, φ_B: 体积分数; w_A, w_B: 质量分数; ρ_A, ρ_B: 密度 (g/cm³)"
        },
        lang["mode_mass_to_vol"]: {
            "formula": r"\phi_A = \frac{w_A / \rho_A}{w_A / \rho_A + w_B / \rho_B}",
            "vars": "w_A, w_B: 质量分数; φ_A, φ_B: 体积分数; ρ_A, ρ_B: 密度 (g/cm³)"
        }
    }
    
    if conversion_mode in formula_dict:
        st.latex(formula_dict[conversion_mode]["formula"])
        st.markdown(f"**{lang['formula_where']}** {formula_dict[conversion_mode]['vars']}")

# 使用说明
with st.expander(f"📖 {lang['usage_instructions']}", expanded=False):
    st.markdown(f"""
    {lang["instruction_1"]}
    
    {lang["instruction_2"]}
    
    {lang["instruction_3"]}
    
    {lang["instruction_4"]}
    """)

# 注意事项
st.markdown(f"""
<div class="warning-box">
{lang["note"]}
</div>
""", unsafe_allow_html=True)

# 页脚
st.markdown("---")
st.markdown("""
<div style="text-align: center; color: #7f8c8d; padding: 1rem;">
    <small>🧪 溶剂分数转换器 | 基于理想混合理论 | Made with Streamlit</small>
</div>
""", unsafe_allow_html=True)