import React, { useState, useEffect, useCallback } from 'react';
import {
  BarChart,
  Bar,
  XAxis,
  YAxis,
  Tooltip,
  ResponsiveContainer,
  Cell,
} from 'recharts';
import {
  X,
  Plus,
  Trash2,
  TestTube,
  Loader2,
  AlertTriangle,
} from 'lucide-react';
import {
  getModels,
  createModel,
  updateModel,
  deleteModel,
  testModel,
  getConfig,
  updateConfig,
  testVlm,
  getPdfs,
  deletePdf,
  getProgress,
  resetProgressTopic,
  backupDatabase,
  restoreDatabase,
  downloadExamPdf,
} from '../lib/api';

function ToggleSwitch({ checked, onChange }) {
  return (
    <button
      className={`toggle-switch ${checked ? 'on' : ''}`}
      onClick={() => onChange(!checked)}
      aria-label="Toggle"
    />
  );
}

function Modal({ title, onClose, children }) {
  return (
    <div className="modal-overlay" onClick={onClose}>
      <div className="modal-content" onClick={(e) => e.stopPropagation()}>
        <div className="modal-header">
          <h3>{title}</h3>
          <button onClick={onClose} className="modal-close-btn">
            <X size={16} />
          </button>
        </div>
        {children}
      </div>
    </div>
  );
}

export default function Settings() {
  const [activeTab, setActiveTab] = useState('models');

  // Models tab
  const [models, setModels] = useState([]);
  const [modelModalOpen, setModelModalOpen] = useState(false);
  const [editingModel, setEditingModel] = useState(null);
  const [modelForm, setModelForm] = useState({
    name: '',
    api_base: '',
    api_key: '',
    provider: 'openai',
    is_default_main: false,
    is_default_fork: false,
    is_default_exam: false,
  });
  const [modelLoading, setModelLoading] = useState(false);
  const [testResults, setTestResults] = useState({});

  // PDFs & VLM tab
  const [pdfs, setPdfs] = useState([]);
  const [vlmUrl, setVlmUrl] = useState('');
  const [vlmSaving, setVlmSaving] = useState(false);
  const [vlmTestResult, setVlmTestResult] = useState(null);

  // Progress tab
  const [progress, setProgress] = useState([]);
  const [restoreFile, setRestoreFile] = useState(null);
  const [restoreLoading, setRestoreLoading] = useState(false);

  const refreshModels = useCallback(async () => {
    try {
      const rows = await getModels();
      setModels(rows);
    } catch (err) {
      console.error('[Settings] refresh models error:', err.message);
    }
  }, []);

  const refreshPdfs = useCallback(async () => {
    try {
      const rows = await getPdfs();
      setPdfs(rows);
    } catch (err) {
      console.error('[Settings] refresh pdfs error:', err.message);
    }
  }, []);

  const refreshProgress = useCallback(async () => {
    try {
      const rows = await getProgress();
      setProgress(rows);
    } catch (err) {
      console.error('[Settings] refresh progress error:', err.message);
    }
  }, []);

  const loadConfig = useCallback(async () => {
    try {
      const cfg = await getConfig();
      if (cfg.vlm_endpoint) {
        setVlmUrl(cfg.vlm_endpoint);
      }
    } catch (err) {
      console.error('[Settings] load config error:', err.message);
    }
  }, []);

  useEffect(() => {
    refreshModels();
    refreshPdfs();
    refreshProgress();
    loadConfig();
  }, []);

  // Model handlers
  const openAddModel = () => {
    setEditingModel(null);
    setModelForm({
      name: '',
      api_base: '',
      api_key: '',
      provider: 'openai',
      is_default_main: false,
      is_default_fork: false,
      is_default_exam: false,
    });
    setModelModalOpen(true);
  };

  const openEditModel = (model) => {
    setEditingModel(model);
    setModelForm({
      name: model.name || '',
      api_base: model.api_base || '',
      api_key: model.api_key || '',
      provider: model.provider || 'openai',
      is_default_main: !!model.is_default_main,
      is_default_fork: !!model.is_default_fork,
      is_default_exam: !!model.is_default_exam,
    });
    setModelModalOpen(true);
  };

  const handleSaveModel = async () => {
    if (!modelForm.name || !modelForm.api_base) return;
    setModelLoading(true);
    try {
      const body = {
        name: modelForm.name,
        api_base: modelForm.api_base,
        api_key: modelForm.api_key,
        provider: modelForm.provider,
        is_default_main: modelForm.is_default_main,
        is_default_fork: modelForm.is_default_fork,
        is_default_exam: modelForm.is_default_exam,
      };
      if (editingModel) {
        await updateModel(editingModel.id, body);
      } else {
        await createModel(body);
      }
      await refreshModels();
      setModelModalOpen(false);
    } catch (err) {
      alert(err.message);
    } finally {
      setModelLoading(false);
    }
  };

  const handleDeleteModel = async (id) => {
    if (!window.confirm('¿Eliminar este modelo? No se puede recuperar.')) return;
    try {
      await deleteModel(id);
      await refreshModels();
    } catch (err) {
      alert(err.message);
    }
  };

  const handleTestModel = async (id) => {
    setTestResults((prev) => ({ ...prev, [id]: { loading: true } }));
    try {
      const result = await testModel(id);
      setTestResults((prev) => ({ ...prev, [id]: { loading: false, result } }));
    } catch (err) {
      setTestResults((prev) => ({ ...prev, [id]: { loading: false, error: err.message } }));
    }
  };

  const handleToggleDefault = async (model, field) => {
    const newValue = !model[field];
    try {
      await updateModel(model.id, { [field]: newValue });
      await refreshModels();
    } catch (err) {
      alert(err.message);
    }
  };

  // VLM handlers
  const handleSaveVlm = async () => {
    setVlmSaving(true);
    try {
      await updateConfig('vlm_endpoint', vlmUrl);
      setVlmTestResult({ success: true, message: 'Guardado' });
    } catch (err) {
      setVlmTestResult({ success: false, message: err.message });
    } finally {
      setVlmSaving(false);
    }
  };

  const handleTestVlm = async () => {
    setVlmTestResult({ loading: true });
    try {
      const result = await testVlm(vlmUrl);
      setVlmTestResult({
        success: result.success,
        message: result.success
          ? `${result.message} (${result.latency_ms}ms)`
          : result.message,
      });
    } catch (err) {
      setVlmTestResult({
        success: false,
        message: err.message,
      });
    }
  };

  const handleDeletePdf = async (id) => {
    if (!window.confirm('¿Eliminar este PDF?')) return;
    try {
      await deletePdf(id);
      await refreshPdfs();
    } catch (err) {
      alert(err.message);
    }
  };

  // Progress handlers
  const handleResetTopic = async (topic) => {
    if (!window.confirm(`¿Resetear progreso de "${topic}"?`)) return;
    try {
      await resetProgressTopic(topic);
      await refreshProgress();
    } catch (err) {
      alert(err.message);
    }
  };

  const handleDownloadBackup = async () => {
    try {
      await backupDatabase();
    } catch (err) {
      alert(err.message);
    }
  };

  const handleRestoreBackup = async () => {
    if (!restoreFile) return;
    if (!window.confirm('¿Restaurar base de datos? Se reemplazará el estado actual.')) return;
    setRestoreLoading(true);
    try {
      await restoreDatabase(restoreFile);
      window.location.reload();
    } catch (err) {
      alert(err.message);
      setRestoreLoading(false);
    }
  };

  const progressChartData = progress.map((p) => ({
    name: p.topic,
    pct: p.percentage,
    fill:
      p.percentage >= 80
        ? 'var(--accent-green)'
        : p.percentage >= 50
        ? 'var(--accent-amber)'
        : 'var(--accent-coral)',
  }));

  return (
    <div className="settings-container">
      <h1
        style={{
          fontSize: 20,
          fontWeight: 700,
          color: 'var(--text-primary)',
          marginBottom: 24,
        }}
      >
        Settings
      </h1>

      <div className="settings-tabs">
        <button
          className={`settings-tab ${activeTab === 'models' ? 'active' : ''}`}
          onClick={() => setActiveTab('models')}
        >
          Modelos
        </button>
        <button
          className={`settings-tab ${activeTab === 'pdfs' ? 'active' : ''}`}
          onClick={() => setActiveTab('pdfs')}
        >
          PDFs & VLM
        </button>
        <button
          className={`settings-tab ${activeTab === 'progress' ? 'active' : ''}`}
          onClick={() => setActiveTab('progress')}
        >
          Progreso
        </button>
        <button
          className={`settings-tab ${activeTab === 'backup' ? 'active' : ''}`}
          onClick={() => setActiveTab('backup')}
        >
          Backup
        </button>
        <button
          className={`settings-tab ${activeTab === 'datos' ? 'active' : ''}`}
          onClick={() => setActiveTab('datos')}
        >
          Datos
        </button>
      </div>

      {/* Tab 1: Modelos */}
      {activeTab === 'models' && (
        <div>
          <div style={{ display: 'flex', justifyContent: 'flex-end', marginBottom: 16 }}>
            <button className="btn btn-primary" onClick={openAddModel}>
              <Plus size={14} style={{ marginRight: 6, verticalAlign: 'middle' }} />
              Add Model
            </button>
          </div>

          <table className="settings-table">
            <thead>
              <tr>
                <th>Name</th>
                <th>Provider</th>
                <th>API Base</th>
                <th style={{ textAlign: 'center' }}>Main</th>
                <th style={{ textAlign: 'center' }}>Fork</th>
                <th style={{ textAlign: 'center' }}>Exam</th>
                <th>Actions</th>
              </tr>
            </thead>
            <tbody>
              {models.map((model) => (
                <tr key={model.id}>
                  <td>
                    <span style={{ fontWeight: 500 }}>{model.name}</span>
                  </td>
                  <td>
                    <span className={`provider-badge ${model.provider}`}>
                      {model.provider}
                    </span>
                  </td>
                  <td>
                    <span style={{ color: 'var(--text-secondary)', fontSize: 12 }}>
                      {model.api_base}
                    </span>
                  </td>
                  <td style={{ textAlign: 'center' }}>
                    <ToggleSwitch
                      checked={!!model.is_default_main}
                      onChange={() => handleToggleDefault(model, 'is_default_main')}
                    />
                  </td>
                  <td style={{ textAlign: 'center' }}>
                    <ToggleSwitch
                      checked={!!model.is_default_fork}
                      onChange={() => handleToggleDefault(model, 'is_default_fork')}
                    />
                  </td>
                  <td style={{ textAlign: 'center' }}>
                    <ToggleSwitch
                      checked={!!model.is_default_exam}
                      onChange={() => handleToggleDefault(model, 'is_default_exam')}
                    />
                  </td>
                  <td>
                    <div style={{ display: 'flex', gap: 6, alignItems: 'center' }}>
                      <button
                        className="btn btn-sm btn-secondary"
                        onClick={() => handleTestModel(model.id)}
                        disabled={testResults[model.id]?.loading}
                      >
                        {testResults[model.id]?.loading ? (
                          <Loader2 size={12} style={{ animation: 'spin 1s linear infinite' }} />
                        ) : (
                          <TestTube size={12} />
                        )}
                        Test
                      </button>
                      {testResults[model.id]?.result && (
                        <span style={{ fontSize: 11, color: 'var(--accent-green)' }}>
                          {testResults[model.id].result.latency_ms}ms
                        </span>
                      )}
                      {testResults[model.id]?.error && (
                        <span style={{ fontSize: 11, color: 'var(--accent-coral)' }}>
                          Error
                        </span>
                      )}
                      <button
                        className="btn btn-sm btn-secondary"
                        onClick={() => openEditModel(model)}
                      >
                        Edit
                      </button>
                      <button
                        className="btn btn-sm btn-danger"
                        onClick={() => handleDeleteModel(model.id)}
                      >
                        <Trash2 size={12} />
                      </button>
                    </div>
                  </td>
                </tr>
              ))}
              {models.length === 0 && (
                <tr>
                  <td colSpan={7} style={{ textAlign: 'center', color: 'var(--text-tertiary)' }}>
                    No hay modelos configurados
                  </td>
                </tr>
              )}
            </tbody>
          </table>
        </div>
      )}

      {/* Tab 2: PDFs & VLM */}
      {activeTab === 'pdfs' && (
        <div>
          <div style={{ marginBottom: 24 }}>
            <h2
              style={{
                fontSize: 14,
                fontWeight: 600,
                color: 'var(--text-primary)',
                marginBottom: 12,
              }}
            >
              VLM Endpoint
            </h2>
            <div style={{ display: 'flex', gap: 8, alignItems: 'center' }}>
              <input
                type="text"
                value={vlmUrl}
                onChange={(e) => setVlmUrl(e.target.value)}
                placeholder="https://vlm.example.com/v1/chat"
                className="vlm-input"
              />
              <button className="btn btn-secondary" onClick={handleSaveVlm} disabled={vlmSaving}>
                {vlmSaving ? (
                  <Loader2 size={12} style={{ animation: 'spin 1s linear infinite', marginRight: 6 }} />
                ) : null}
                Guardar
              </button>
              <button className="btn btn-secondary" onClick={handleTestVlm}>
                Test VLM
              </button>
            </div>
            {vlmTestResult && (
              <div
                style={{
                  marginTop: 8,
                  fontSize: 12,
                  color: vlmTestResult.loading ? 'var(--text-tertiary)' : vlmTestResult.success ? 'var(--accent-green)' : 'var(--accent-coral)',
                  display: 'flex',
                  alignItems: 'center',
                  gap: 6,
                }}
              >
                {vlmTestResult.loading ? (
                  <Loader2 size={12} style={{ animation: 'spin 1s linear infinite' }} />
                ) : vlmTestResult.success ? (
                  <TestTube size={12} />
                ) : (
                  <AlertTriangle size={12} />
                )}
                {vlmTestResult.message}
              </div>
            )}
          </div>

          <div>
            <h2
              style={{
                fontSize: 14,
                fontWeight: 600,
                color: 'var(--text-primary)',
                marginBottom: 12,
              }}
            >
              PDFs cargados
            </h2>
            <table className="settings-table">
              <thead>
                <tr>
                  <th>Nombre</th>
                  <th>Orden</th>
                  <th>Acciones</th>
                </tr>
              </thead>
              <tbody>
                {pdfs.map((pdf) => (
                  <tr key={pdf.id}>
                    <td>{pdf.filename}</td>
                    <td>{pdf.sort_order}</td>
                    <td>
                      <button
                        className="btn btn-sm btn-danger"
                        onClick={() => handleDeletePdf(pdf.id)}
                      >
                        <Trash2 size={12} />
                      </button>
                    </td>
                  </tr>
                ))}
                {pdfs.length === 0 && (
                  <tr>
                    <td colSpan={3} style={{ textAlign: 'center', color: 'var(--text-tertiary)' }}>
                      No hay PDFs cargados
                    </td>
                  </tr>
                )}
              </tbody>
            </table>
          </div>
        </div>
      )}

      {/* Tab 3: Progreso */}
      {activeTab === 'progress' && (
        <div>
          <div style={{ marginBottom: 24 }}>
            <h2
              style={{
                fontSize: 14,
                fontWeight: 600,
                color: 'var(--text-primary)',
                marginBottom: 12,
              }}
            >
              Gráfico de progreso
            </h2>
            <div className="progress-chart-container">
              <ResponsiveContainer width="100%" height="100%">
                <BarChart data={progressChartData} margin={{ top: 8, right: 8, left: 0, bottom: 0 }}>
                  <XAxis
                    dataKey="name"
                    tick={{ fill: 'var(--text-secondary)', fontSize: 11 }}
                    axisLine={{ stroke: 'var(--border)' }}
                    tickLine={false}
                  />
                  <YAxis
                    tick={{ fill: 'var(--text-secondary)', fontSize: 11 }}
                    axisLine={false}
                    tickLine={false}
                    domain={[0, 100]}
                    unit="%"
                  />
                  <Tooltip
                    contentStyle={{
                      background: 'var(--bg-elevated)',
                      border: '1px solid var(--border)',
                      borderRadius: 'var(--radius-md)',
                      color: 'var(--text-primary)',
                      fontSize: 12,
                    }}
                    itemStyle={{ color: 'var(--text-primary)' }}
                    formatter={(value) => [`${value}%`, 'Porcentaje']}
                  />
                  <Bar dataKey="pct" radius={[4, 4, 0, 0]}>
                    {progressChartData.map((entry, index) => (
                      <Cell key={`cell-${index}`} fill={entry.fill} />
                    ))}
                  </Bar>
                </BarChart>
              </ResponsiveContainer>
            </div>
          </div>

          <table className="settings-table">
            <thead>
              <tr>
                <th>Topic</th>
                <th>Exercises Done</th>
                <th>Exercises Correct</th>
                <th>Percentage</th>
                <th>Actions</th>
              </tr>
            </thead>
            <tbody>
              {progress.map((p) => (
                <tr key={p.topic}>
                  <td>
                    <span style={{ fontWeight: 500 }}>{p.topic}</span>
                  </td>
                  <td>{p.exercises_done}</td>
                  <td>{p.exercises_correct}</td>
                  <td>
                    <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
                      <div className="progress-bar-bg" style={{ width: 120 }}>
                        <div
                          className="progress-bar-fill"
                          style={{
                            width: `${p.percentage}%`,
                            background:
                              p.percentage >= 80
                                ? 'var(--accent-green)'
                                : p.percentage >= 50
                                ? 'var(--accent-amber)'
                                : 'var(--accent-coral)',
                          }}
                        />
                      </div>
                      <span style={{ fontSize: 12, fontWeight: 600, minWidth: 32 }}>
                        {p.percentage}%
                      </span>
                    </div>
                  </td>
                  <td>
                    <button
                      className="btn btn-sm btn-danger"
                      onClick={() => handleResetTopic(p.topic)}
                    >
                      Reset
                    </button>
                  </td>
                </tr>
              ))}
              {progress.length === 0 && (
                <tr>
                  <td colSpan={5} style={{ textAlign: 'center', color: 'var(--text-tertiary)' }}>
                    No hay progreso registrado
                  </td>
                </tr>
              )}
            </tbody>
          </table>
        </div>
      )}

      {/* Tab 4: Backup */}
      {activeTab === 'backup' && (
        <div>
          <div style={{ marginBottom: 24 }}>
            <h2
              style={{
                fontSize: 14,
                fontWeight: 600,
                color: 'var(--text-primary)',
                marginBottom: 12,
              }}
            >
              Base de datos
            </h2>
            <div style={{ display: 'flex', gap: 12, alignItems: 'center', flexWrap: 'wrap' }}>
              <button className="btn btn-secondary" onClick={handleDownloadBackup}>
                Download Backup
              </button>
              <div style={{ display: 'flex', gap: 8, alignItems: 'center' }}>
                <input
                  type="file"
                  accept=".db"
                  onChange={(e) => setRestoreFile(e.target.files?.[0] || null)}
                />
                <button
                  className="btn btn-primary"
                  onClick={handleRestoreBackup}
                  disabled={!restoreFile || restoreLoading}
                >
                  {restoreLoading ? (
                    <Loader2 size={12} style={{ animation: 'spin 1s linear infinite', marginRight: 6 }} />
                  ) : null}
                  Restore Backup
                </button>
              </div>
            </div>
          </div>
        </div>
      )}

      {/* Tab 5: Datos */}
      {activeTab === 'datos' && (
        <div>
          <div style={{ marginBottom: 24 }}>
            <h2
              style={{
                fontSize: 14,
                fontWeight: 600,
                color: 'var(--text-primary)',
                marginBottom: 12,
              }}
            >
              Exportar examen simulado
            </h2>
            <p style={{ fontSize: 12, color: 'var(--text-secondary)', marginBottom: 12 }}>
              Genera un PDF con los 20 temas más recientes de tu progreso.
            </p>
            <button className="btn btn-primary" onClick={downloadExamPdf}>
              Exportar examen simulado
            </button>
          </div>
        </div>
      )}

      {/* Model Modal */}
      {modelModalOpen && (
        <Modal
          title={editingModel ? 'Editar Modelo' : 'Agregar Modelo'}
          onClose={() => setModelModalOpen(false)}
        >
          <div className="form-group">
            <label>Nombre</label>
            <input
              value={modelForm.name}
              onChange={(e) => setModelForm((f) => ({ ...f, name: e.target.value }))}
              placeholder="gpt-4o"
            />
          </div>
          <div className="form-group">
            <label>API Base</label>
            <input
              value={modelForm.api_base}
              onChange={(e) => setModelForm((f) => ({ ...f, api_base: e.target.value }))}
              placeholder="https://api.openai.com/v1"
            />
          </div>
          <div className="form-group">
            <label>API Key</label>
            <input
              type="password"
              value={modelForm.api_key}
              onChange={(e) => setModelForm((f) => ({ ...f, api_key: e.target.value }))}
              placeholder="sk-..."
            />
          </div>
          <div className="form-group">
            <label>Provider</label>
            <select
              value={modelForm.provider}
              onChange={(e) => setModelForm((f) => ({ ...f, provider: e.target.value }))}
            >
              <option value="openai">openai</option>
              <option value="anthropic">anthropic</option>
            </select>
          </div>
          <div className="form-group">
            <label style={{ display: 'flex', alignItems: 'center', gap: 8, marginBottom: 8 }}>
              <ToggleSwitch
                checked={modelForm.is_default_main}
                onChange={(v) =>
                  setModelForm((f) => ({
                    ...f,
                    is_default_main: v,
                    is_default_fork: v ? false : f.is_default_fork,
                    is_default_exam: v ? false : f.is_default_exam,
                  }))
                }
              />
              Default Main
              <span className="role-dot main" style={{ marginLeft: 4 }} />
            </label>
          </div>
          <div className="form-group">
            <label style={{ display: 'flex', alignItems: 'center', gap: 8, marginBottom: 8 }}>
              <ToggleSwitch
                checked={modelForm.is_default_fork}
                onChange={(v) =>
                  setModelForm((f) => ({
                    ...f,
                    is_default_fork: v,
                    is_default_main: v ? false : f.is_default_main,
                    is_default_exam: v ? false : f.is_default_exam,
                  }))
                }
              />
              Default Fork
              <span className="role-dot fork" style={{ marginLeft: 4 }} />
            </label>
          </div>
          <div className="form-group">
            <label style={{ display: 'flex', alignItems: 'center', gap: 8, marginBottom: 8 }}>
              <ToggleSwitch
                checked={modelForm.is_default_exam}
                onChange={(v) =>
                  setModelForm((f) => ({
                    ...f,
                    is_default_exam: v,
                    is_default_main: v ? false : f.is_default_main,
                    is_default_fork: v ? false : f.is_default_fork,
                  }))
                }
              />
              Default Exam
              <span className="role-dot exam" style={{ marginLeft: 4 }} />
            </label>
          </div>
          <div className="form-actions">
            <button className="btn btn-secondary" onClick={() => setModelModalOpen(false)}>
              Cancelar
            </button>
            <button className="btn btn-primary" onClick={handleSaveModel} disabled={modelLoading}>
              {modelLoading ? (
                <Loader2 size={14} style={{ animation: 'spin 1s linear infinite', marginRight: 6 }} />
              ) : null}
              Guardar
            </button>
          </div>
        </Modal>
      )}
    </div>
  );
}