using System;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using Microsoft.Win32;

namespace TimerApp
{
    public partial class MainForm : Form
    {
        private ActivityMonitor _monitor = null!;
        private AppSettings _settings;
        private RestForm? _restForm;

        // Colors
        private Color _darkBg = Color.FromArgb(30, 30, 30);
        private Color _lightBg = Color.FromArgb(240, 240, 240);
        private Color _darkPanel = Color.FromArgb(45, 45, 48);
        private Color _lightPanel = Color.FromArgb(200, 200, 200);
        private Color _darkText = Color.White;
        private Color _lightText = Color.Black;

        // Drag window support
        [DllImport("user32.dll")]
        public static extern bool ReleaseCapture();
        [DllImport("user32.dll")]
        public static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);
        [DllImport("user32.dll")]
        static extern bool CreateCaret(IntPtr hWnd, IntPtr hBitmap, int nWidth, int nHeight);
        [DllImport("user32.dll")]
        static extern bool ShowCaret(IntPtr hWnd);

        private const int WM_NCLBUTTONDOWN = 0xA1;
        private const int HT_CAPTION = 0x2;

        public MainForm()
        {
            InitializeComponent();
            // 在窗口显示前设置背景色，避免白色闪烁
            // 确保所有控件在显示前都有正确的背景色
            this.SuspendLayout();

            // 先加载设置，以便知道应该使用什么背景色
            _settings = AppSettings.Load();
            bool dark = _settings.IsDarkMode;
            Color bg = dark ? _darkBg : _lightBg;

            this.BackColor = bg;
            pnlSettings.BackColor = bg;
            lblTimeLeft.BackColor = bg;
            lblStatus.BackColor = bg;
            label1.BackColor = bg;
            label2.BackColor = bg;

            // 设置文本框和按钮的初始背景色
            Color panelColor = dark ? _darkPanel : _lightPanel;
            txtWork.BackColor = panelColor;
            txtRest.BackColor = panelColor;
            btnWorkMinus.BackColor = panelColor;
            btnWorkPlus.BackColor = panelColor;
            btnRestMinus.BackColor = panelColor;
            btnRestPlus.BackColor = panelColor;
            btnStartStop.BackColor = dark ? Color.FromArgb(63, 63, 70) : Color.White;
            btnReset.BackColor = dark ? Color.FromArgb(63, 63, 70) : Color.White;
            btnPause.BackColor = dark ? Color.FromArgb(63, 63, 70) : Color.White;

            // 优化绘制，减少闪烁
            this.SetStyle(ControlStyles.AllPaintingInWmPaint |
                         ControlStyles.UserPaint |
                         ControlStyles.DoubleBuffer |
                         ControlStyles.ResizeRedraw, true);

            this.ResumeLayout(false);
        }

        private void MainForm_Load(object sender, EventArgs e)
        {
            // Settings already loaded in constructor, just update text
            txtWork.Text = _settings.WorkMinutes.ToString();
            txtRest.Text = _settings.RestMinutes.ToString();

            // Apply Theme - 确保在窗口显示前应用主题
            ApplyTheme();

            // 强制刷新背景色，确保所有控件都正确显示
            this.Invalidate(true);
            pnlSettings.Invalidate(true);
            this.Update();

            // Init monitor
            _monitor = new ActivityMonitor();
            ApplySettings();

            // Bind events
            _monitor.StateChanged += Monitor_StateChanged;
            _monitor.WorkProgressChanged += Monitor_WorkProgressChanged;
            _monitor.RestStarted += Monitor_RestStarted;
            _monitor.RestEnded += Monitor_RestEnded;
            _monitor.RestProgressChanged += Monitor_RestProgressChanged;

            // Numeric Buttons
            btnWorkMinus.Click += (s, ev) => AdjustTime(txtWork, -1, 1, 120);
            btnWorkPlus.Click += (s, ev) => AdjustTime(txtWork, 1, 1, 120);
            btnRestMinus.Click += (s, ev) => AdjustTime(txtRest, -1, 1, 30);
            btnRestPlus.Click += (s, ev) => AdjustTime(txtRest, 1, 1, 30);

            // Manual input validation
            txtWork.KeyPress += ValidateDigitInput;
            txtRest.KeyPress += ValidateDigitInput;
            txtWork.Leave += (s, ev) => ValidateRange((TextBox)s!, 1, 120);
            txtRest.Leave += (s, ev) => ValidateRange((TextBox)s!, 1, 30);

            // Focus handling (remove custom caret)
            txtWork.KeyDown += TextBox_KeyDown;
            txtRest.KeyDown += TextBox_KeyDown;

            // Setup TextBoxes with Panels for vertical centering
            SetupTextBoxPanel(txtWork, pnlSettings);
            SetupTextBoxPanel(txtRest, pnlSettings);

            // 确保容器背景色正确（在 SetupTextBoxPanel 之后再次应用主题）
            UpdateTextBoxStyle(txtWork, _settings.IsDarkMode);
            UpdateTextBoxStyle(txtRest, _settings.IsDarkMode);

            // 再次确保 pnlSettings 的背景色正确
            bool dark = _settings.IsDarkMode;
            Color bg = dark ? _darkBg : _lightBg;
            pnlSettings.BackColor = bg;
            pnlSettings.Refresh();

            _monitor.Start();

            SystemEvents.PowerModeChanged += OnPowerModeChanged;

            // Set tray icon
            try
            {
                // Generate and set custom icon
                Icon icon = IconGenerator.GenerateClockIcon(64);
                this.Icon = icon;
                notifyIcon1.Icon = icon;

                contextMenuStrip1.ShowImageMargin = true;
                toolStripMenuItemShow.Image = null;
                toolStripMenuItemExit.Image = null;
            }
            catch
            {
                 notifyIcon1.Icon = SystemIcons.Application;
                 contextMenuStrip1.ShowImageMargin = true;
                 toolStripMenuItemShow.Image = null;
                 toolStripMenuItemExit.Image = null;
            }

            UpdateStatusUI();
        }

        private void AdjustTime(TextBox txt, int delta, int min, int max)
        {
            if (int.TryParse(txt.Text, out int val))
            {
                val += delta;
                if (val < min) val = min;
                if (val > max) val = max;
                txt.Text = val.ToString();
            }
        }

        private void ValidateDigitInput(object? sender, KeyPressEventArgs e)
        {
            // Allow control keys (backspace, etc.) and digits
            if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar))
            {
                e.Handled = true;
            }
        }

        private void SetupTextBoxPanel(TextBox txt, Panel parent)
        {
            // Create a container panel for the textbox
            Panel container = new Panel();
            container.Size = txt.Size; // 60x30
            container.Location = txt.Location;
            // 确保容器背景色与文本框背景色一致
            container.BackColor = txt.BackColor;

            // Adjust textbox to be centered inside
            txt.Parent = container;
            txt.Location = new Point(0, (container.Height - txt.Height) / 2); // Center vertically
            txt.Dock = DockStyle.None;
            txt.Width = container.Width;
            txt.BorderStyle = BorderStyle.None;

            // Add container to parent
            parent.Controls.Add(container);

            // Ensure correct tab order and tagging
            container.Tag = txt.Tag; // Copy tag if any

            // 确保容器背景色与父容器一致（如果文本框背景色与父容器不同）
            // 这里容器应该使用文本框的背景色，因为它是文本框的容器
        }

        private void ValidateRange(TextBox txt, int min, int max)
        {
            if (int.TryParse(txt.Text, out int val))
            {
                if (val < min) txt.Text = min.ToString();
                if (val > max) txt.Text = max.ToString();
            }
            else
            {
                txt.Text = min.ToString(); // Default to min if invalid/empty
            }

            // Clear selection on leave
            txt.SelectionLength = 0;
        }

        // CustomCaret removed to use system caret with centered text

        private void TextBox_KeyDown(object? sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
            {
                // Lose focus by focusing the label
                lblStatus.Focus();
                e.Handled = true;
                e.SuppressKeyPress = true; // Prevent 'ding' sound
            }
        }

        private void ApplyTheme()
        {
            bool dark = _settings.IsDarkMode;
            Color bg = dark ? _darkBg : _lightBg;
            Color panel = dark ? _darkPanel : _lightPanel;
            Color text = dark ? _darkText : _lightText;
            Color btnBg = dark ? Color.FromArgb(45, 45, 48) : Color.White;

            // 确保窗口和所有面板的背景色一致
            this.BackColor = bg;
            pnlTitle.BackColor = panel;
            // 强制设置 pnlSettings 的背景色，确保与窗口背景色一致
            pnlSettings.BackColor = bg;
            pnlSettings.Invalidate(); // 强制重绘
            lblTimeLeft.BackColor = bg;
            lblStatus.BackColor = bg;
            label1.BackColor = bg;
            label2.BackColor = bg;

            // 确保所有标签都使用正确的背景色
            foreach (Control ctrl in pnlSettings.Controls)
            {
                if (ctrl is Label label && label.BackColor != bg)
                {
                    label.BackColor = bg;
                }
            }

            lblTitle.ForeColor = dark ? Color.LightGray : Color.FromArgb(64, 64, 64);
            lblTimeLeft.ForeColor = text;

            label1.ForeColor = dark ? Color.LightGray : Color.DimGray;
            label2.ForeColor = dark ? Color.LightGray : Color.DimGray;

            // Update buttons
            UpdateButtonStyle(btnStartStop, dark);
            UpdateButtonStyle(btnReset, dark);
            UpdateButtonStyle(btnPause, dark);
            UpdateButtonStyle(btnHide, dark);

            // Numeric buttons and text
            UpdateNumericButtonStyle(btnWorkMinus, dark);
            UpdateNumericButtonStyle(btnWorkPlus, dark);
            UpdateNumericButtonStyle(btnRestMinus, dark);
            UpdateNumericButtonStyle(btnRestPlus, dark);
            UpdateTextBoxStyle(txtWork, dark);
            UpdateTextBoxStyle(txtRest, dark);

            // Title buttons
            btnClose.ForeColor = text;
            btnMin.ForeColor = text;

            // Set hover background colors for title buttons
            if (dark)
            {
                // 深色模式下使用深色悬停背景
                btnClose.FlatAppearance.MouseOverBackColor = Color.FromArgb(232, 17, 35); // 深色模式下的红色（稍微暗一点）
                btnMin.FlatAppearance.MouseOverBackColor = Color.FromArgb(63, 63, 70);
                btnTheme.FlatAppearance.MouseOverBackColor = Color.FromArgb(63, 63, 70);
            }
            else
            {
                // 浅色模式下使用浅色悬停背景
                btnClose.FlatAppearance.MouseOverBackColor = Color.Red;
                btnMin.FlatAppearance.MouseOverBackColor = Color.FromArgb(220, 220, 220); // 浅灰色，接近标题栏背景
                btnTheme.FlatAppearance.MouseOverBackColor = Color.FromArgb(220, 220, 220); // 浅灰色，接近标题栏背景
            }

            // Theme button with Segoe MDL2 Assets
            btnTheme.ForeColor = text;
            btnTheme.Font = new Font("Segoe MDL2 Assets", 10F, FontStyle.Regular, GraphicsUnit.Point);
            btnTheme.Text = dark ? "\uE706" : "\uE708"; // Sun : Moon

            // Context Menu Theme
            // 浅色模式下使用白色背景，深色模式使用深色面板色
            Color menuBg = dark ? panel : Color.White;
            var menuRenderer = new ToolStripProfessionalRenderer(new CustomColorTable(dark, menuBg));
            contextMenuStrip1.Renderer = menuRenderer;
            contextMenuStrip1.BackColor = menuBg;
            contextMenuStrip1.ForeColor = dark ? text : Color.Black;

            UpdateStatusUI(); // Re-apply status colors
        }

        private class CustomColorTable : ProfessionalColorTable
        {
            private bool _dark;
            private Color _backColor;

            public CustomColorTable(bool dark, Color backColor)
            {
                _dark = dark;
                _backColor = backColor;
            }

            public override Color MenuItemSelected => _dark ? Color.FromArgb(63, 63, 70) : base.MenuItemSelected;
            public override Color MenuItemBorder => _dark ? Color.FromArgb(63, 63, 70) : base.MenuItemBorder;
            public override Color MenuBorder => _dark ? Color.FromArgb(45, 45, 48) : base.MenuBorder;

            // Fix white margin in dark mode, and set margin color to background color in light mode
            public override Color ImageMarginGradientBegin => _backColor;
            public override Color ImageMarginGradientMiddle => _backColor;
            public override Color ImageMarginGradientEnd => _backColor;
        }

        private void UpdateButtonStyle(Button btn, bool dark)
        {
            btn.BackColor = dark ? Color.FromArgb(63, 63, 70) : Color.White;
            btn.ForeColor = dark ? Color.White : Color.Black;
        }

        private void UpdateNumericButtonStyle(Button btn, bool dark)
        {
            btn.BackColor = dark ? Color.FromArgb(45, 45, 48) : Color.FromArgb(230, 230, 230);
            btn.ForeColor = dark ? Color.White : Color.Black;
        }

        private void UpdateTextBoxStyle(TextBox txt, bool dark)
        {
            Color bgColor = dark ? Color.FromArgb(45, 45, 48) : Color.White;
            txt.BackColor = bgColor;
            txt.ForeColor = dark ? Color.White : Color.Black;

            // Also update parent container if it exists
            if (txt.Parent is Panel p)
            {
                p.BackColor = bgColor;
            }
        }

        private void btnTheme_Click(object sender, EventArgs e)
        {
            _settings.IsDarkMode = !_settings.IsDarkMode;
            _settings.Save();
            ApplyTheme();
        }

        private void btnStartStop_Click(object sender, EventArgs e)
        {
            // Save settings
            if (int.TryParse(txtWork.Text, out int w)) _settings.WorkMinutes = w;
            if (int.TryParse(txtRest.Text, out int r)) _settings.RestMinutes = r;
            _settings.Save();

            ApplySettings();
            _monitor.RefreshStatus(); // Force update UI
            // MessageBox removed to prevent blocking timer
        }

        private void btnReset_Click(object sender, EventArgs e)
        {
            _monitor.Restart();
        }

        private void btnPause_Click(object sender, EventArgs e)
        {
            if (_monitor.IsPaused)
            {
                _monitor.Resume();
                btnPause.Text = "暂停";
            }
            else
            {
                _monitor.Pause();
                btnPause.Text = "恢复";
            }
        }

        private void ApplySettings()
        {
            int workMin = 20;
            int restMin = 1;
            int.TryParse(txtWork.Text, out workMin);
            int.TryParse(txtRest.Text, out restMin);

            _monitor.WorkDuration = TimeSpan.FromMinutes(workMin);
            _monitor.RestDuration = TimeSpan.FromMinutes(restMin);
            _monitor.IdleThreshold = TimeSpan.FromSeconds(_settings.IdleThresholdSeconds);
        }

        private void Monitor_StateChanged(object? sender, EventArgs e)
        {
            if (InvokeRequired)
            {
                Invoke(new Action<object?, EventArgs>(Monitor_StateChanged), sender, e);
                return;
            }
            UpdateStatusUI();
        }

        private void UpdateStatusUI()
        {
            if (_monitor == null) return;

            bool dark = _settings.IsDarkMode;

            // 更新暂停按钮状态
            if (_monitor.CurrentState == MonitorState.Idle)
            {
                btnPause.Enabled = false;
                btnPause.Text = "暂停";
            }
            else
            {
                btnPause.Enabled = true;
                btnPause.Text = _monitor.IsPaused ? "恢复" : "暂停";
            }

            switch (_monitor.CurrentState)
            {
                case MonitorState.Idle:
                    lblStatus.Text = "状态: 空闲";
                    lblStatus.ForeColor = Color.Gray;
                    lblTimeLeft.Text = "--:--";
                    lblTimeLeft.ForeColor = Color.Gray;
                    break;
                case MonitorState.Working:
                    lblStatus.Text = _monitor.IsPaused ? "状态: 工作中 (已暂停)" : "状态: 工作中";
                    lblStatus.ForeColor = dark ? Color.LightGreen : Color.Green;
                    lblTimeLeft.ForeColor = dark ? Color.White : Color.Black;
                    break;
                case MonitorState.Resting:
                    lblStatus.Text = _monitor.IsPaused ? "状态: 休息中 (已暂停)" : "状态: 休息中";
                    lblStatus.ForeColor = dark ? Color.LightSkyBlue : Color.Blue;
                    lblTimeLeft.ForeColor = dark ? Color.LightSkyBlue : Color.Blue;
                    break;
            }
        }

        private void Monitor_WorkProgressChanged(object? sender, TimeSpan remaining)
        {
            if (InvokeRequired)
            {
                Invoke(new Action<object?, TimeSpan>(Monitor_WorkProgressChanged), sender, remaining);
                return;
            }
            lblTimeLeft.Text = $"{remaining.Minutes:D2}:{remaining.Seconds:D2}";

            // Update tray tooltip
            if (remaining.TotalMinutes < 1)
            {
                notifyIcon1.Text = $"即将休息: {remaining.Seconds}秒";
            }
            else
            {
                notifyIcon1.Text = $"工作中: 剩余 {remaining.Minutes} 分钟";
            }
        }

        private void Monitor_RestStarted(object? sender, EventArgs e)
        {
            if (InvokeRequired)
            {
                Invoke(new Action<object?, EventArgs>(Monitor_RestStarted), sender, e);
                return;
            }

            // Show rest form
            if (_restForm == null || _restForm.IsDisposed)
            {
                _restForm = new RestForm();
                _restForm.SkipRequested += RestForm_SkipRequested;
            }

            _restForm.Show();
        }

        private void RestForm_SkipRequested(object? sender, EventArgs e)
        {
            _monitor.Stop();
            _monitor.Start();
        }

        private void Monitor_RestProgressChanged(object? sender, TimeSpan remaining)
        {
            if (_restForm != null && !_restForm.IsDisposed && _restForm.Visible)
            {
                _restForm.UpdateTime(remaining);
            }
        }

        private void Monitor_RestEnded(object? sender, EventArgs e)
        {
            if (InvokeRequired)
            {
                Invoke(new Action<object?, EventArgs>(Monitor_RestEnded), sender, e);
                return;
            }

            if (_restForm != null && !_restForm.IsDisposed)
            {
                _restForm.Close();
            }

            notifyIcon1.ShowBalloonTip(3000, "休息结束", "继续加油工作吧！", ToolTipIcon.Info);
        }

        private void btnHide_Click(object sender, EventArgs e)
        {
            this.Hide();
            if (!_settings.HasShownMinimizeTip)
            {
                notifyIcon1.ShowBalloonTip(2000, "已隐藏", "程序仍在后台运行，双击托盘图标恢复。", ToolTipIcon.Info);
                _settings.HasShownMinimizeTip = true;
                _settings.Save();
            }
        }

        private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (e.CloseReason == CloseReason.UserClosing)
            {
                e.Cancel = true;
                this.Hide();
                if (!_settings.HasShownMinimizeTip)
                {
                    notifyIcon1.ShowBalloonTip(2000, "已隐藏", "程序仍在后台运行，双击托盘图标恢复。", ToolTipIcon.Info);
                    _settings.HasShownMinimizeTip = true;
                    _settings.Save();
                }
            }
            else
            {
                SystemEvents.PowerModeChanged -= OnPowerModeChanged;
                notifyIcon1.Visible = false;
                notifyIcon1.Dispose();
            }
        }

        private void notifyIcon1_MouseDoubleClick(object? sender, MouseEventArgs e)
        {
            ShowForm();
        }

        private void toolStripMenuItemShow_Click(object? sender, EventArgs e)
        {
            ShowForm();
        }

        private void ShowForm()
        {
            this.Show();
            this.WindowState = FormWindowState.Normal;
            this.Activate();
        }

        public void ActivateFromExternal()
        {
            if (InvokeRequired)
            {
                BeginInvoke(new Action(ActivateFromExternal));
                return;
            }

            this.Show();
            this.WindowState = FormWindowState.Normal;
            this.ShowInTaskbar = true;
            this.BringToFront();
            this.Activate();
            this.TopMost = true;
            this.TopMost = false;
        }

        private void toolStripMenuItemExit_Click(object sender, EventArgs e)
        {
            _monitor.Stop();
            notifyIcon1.Visible = false;
            notifyIcon1.Dispose();
            Application.Exit();
        }

        private void pnlTitle_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                ReleaseCapture();
                SendMessage(Handle, WM_NCLBUTTONDOWN, HT_CAPTION, 0);
            }
        }

        private void btnClose_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void btnMin_Click(object sender, EventArgs e)
        {
            this.WindowState = FormWindowState.Minimized;
        }

        private void OnPowerModeChanged(object sender, PowerModeChangedEventArgs e)
        {
            if (e.Mode == PowerModes.Resume)
            {
                // 系统唤醒时，强制重置媒体播放检测状态，
                // 避免因检测线程挂起导致一直误报“正在播放”而无法进入工作状态。
                NativeMethods.InvalidateMediaCache();
            }
        }
    }
}