import React, { useState, useRef, useEffect, useCallback } from 'react';
import ReactDOM from 'react-dom';
import {
  X, User as UserIcon, Lock, Trash2, AlertTriangle, Activity, RefreshCw, Loader2,
} from 'lucide-react';

const overlay = {
  position: 'fixed', inset: 0, background: 'rgba(0,0,0,0.5)',
  display: 'flex', alignItems: 'center', justifyContent: 'center', zIndex: 1000,
};

const modal = {
  background: 'var(--bg-primary)', borderRadius: 16, padding: 0, width: 560,
  maxWidth: '95vw', maxHeight: '85vh', overflow: 'hidden',
  boxShadow: 'var(--shadow-xl)', display: 'flex', flexDirection: 'column',
};

const header = {
  display: 'flex', justifyContent: 'space-between', alignItems: 'center',
  padding: '20px 24px', borderBottom: '1px solid var(--border-primary)',
};

const tabRow = {
  display: 'flex', gap: 4, padding: '12px 16px 0',
  borderBottom: '1px solid var(--border-primary)',
  flexWrap: 'wrap',
};

const tabBtn = (active) => ({
  display: 'flex', alignItems: 'center', gap: 8,
  padding: '10px 14px', background: 'transparent',
  border: 'none', borderBottom: active ? '2px solid var(--accent-primary)' : '2px solid transparent',
  color: active ? 'var(--accent-primary)' : 'var(--text-secondary)',
  cursor: 'pointer', fontSize: 13.5, fontWeight: 500,
  marginBottom: -1,
});

const body = { padding: 24, overflowY: 'auto', flex: 1 };

const label = { display: 'block', fontSize: 13, fontWeight: 600, color: 'var(--text-secondary)', marginBottom: 6 };

const input = {
  width: '100%', padding: '10px 12px', borderRadius: 8,
  border: '1px solid var(--border-primary)', background: 'var(--bg-secondary)',
  color: 'var(--text-primary)', fontSize: 14, boxSizing: 'border-box',
};

const primaryBtn = {
  padding: '10px 16px', background: 'var(--accent-fill, var(--accent-primary))',
  color: 'var(--accent-on-accent, #fff)', border: 'none', borderRadius: 8,
  cursor: 'pointer', fontSize: 14, fontWeight: 500,
};

const dangerBtn = {
  padding: '10px 16px', background: '#dc2626',
  color: '#fff', border: 'none', borderRadius: 8,
  cursor: 'pointer', fontSize: 14, fontWeight: 500,
};

const statusColors = {
  online: { bg: 'rgba(22,163,74,0.12)', color: '#16a34a', border: 'rgba(22,163,74,0.35)' },
  unavailable: { bg: 'rgba(234,179,8,0.12)', color: '#ca8a04', border: 'rgba(234,179,8,0.35)' },
  error: { bg: 'rgba(220,38,38,0.1)', color: '#dc2626', border: 'rgba(220,38,38,0.3)' },
};

const SettingsModal = ({
  user,
  authToken,
  onUserUpdate,
  onSignOut,
  onClose,
  initialTab = 'profile',
}) => {
  const [activeTab, setActiveTab] = useState(initialTab || 'profile');

  const mouseDownOnOverlay = useRef(false);
  const handleOverlayMouseDown = (e) => {
    mouseDownOnOverlay.current = e.target === e.currentTarget;
  };
  const handleOverlayMouseUp = (e) => {
    if (mouseDownOnOverlay.current && e.target === e.currentTarget) onClose();
    mouseDownOnOverlay.current = false;
  };

  const [firstName, setFirstName] = useState(user?.firstName || '');
  const [lastName, setLastName] = useState(user?.lastName || '');
  const [email, setEmail] = useState(user?.email || '');

  const [currentPassword, setCurrentPassword] = useState('');
  const [newPassword, setNewPassword] = useState('');
  const [confirmPassword, setConfirmPassword] = useState('');

  const [deleteConfirmPassword, setDeleteConfirmPassword] = useState('');
  const [deleteConfirmText, setDeleteConfirmText] = useState('');

  const [message, setMessage] = useState(null);
  const [isSubmitting, setIsSubmitting] = useState(false);

  const [modelStatus, setModelStatus] = useState(null);
  const [statusLoading, setStatusLoading] = useState(false);
  const [statusError, setStatusError] = useState(null);
  const [currentProvider, setCurrentProvider] = useState(null);
  const [switchingProvider, setSwitchingProvider] = useState(null);

  const apiUrl = process.env.REACT_APP_API_URL;

  const extractError = (data, fallback) => {
    if (!data) return fallback;
    if (typeof data.detail === 'string') return data.detail;
    if (Array.isArray(data.detail) && data.detail[0]?.msg) return data.detail[0].msg;
    return fallback;
  };

  const fetchModelStatus = useCallback(async (forceRefresh = false) => {
    setStatusLoading(true);
    setStatusError(null);
    try {
      const qs = forceRefresh ? '?refresh=true' : '';
      const response = await fetch(`${apiUrl}/models/status${qs}`);
      if (!response.ok) {
        throw new Error(`Status request failed (${response.status})`);
      }
      const data = await response.json();
      setModelStatus(data);
    } catch (err) {
      console.warn('Model status check failed; keeping unfiltered provider list.', err);
      setStatusError(err.message || 'Could not load model status.');
      setModelStatus({
        models: [],
        online_providers: null,
        check_failed: true,
        error: err.message || 'Network error',
      });
    } finally {
      setStatusLoading(false);
    }
  }, [apiUrl]);

  const fetchCurrentProvider = useCallback(async () => {
    try {
      const response = await fetch(`${apiUrl}/current-provider`);
      if (response.ok) {
        const data = await response.json();
        setCurrentProvider(data.current_provider);
      }
    } catch {
      /* provider display is best-effort */
    }
  }, [apiUrl]);

  const handleProviderSwitch = async (providerId) => {
    if (providerId === currentProvider || switchingProvider) return;
    setSwitchingProvider(providerId);
    setMessage(null);
    try {
      const response = await fetch(`${apiUrl}/switch-provider`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ provider: providerId }),
      });
      const data = await response.json().catch(() => null);
      if (!response.ok) {
        setMessage({ type: 'error', text: extractError(data, `Could not switch to ${providerId}.`) });
        return;
      }
      setCurrentProvider(providerId);
      setMessage({ type: 'success', text: `Advisors now use the ${providerId} provider.` });
    } catch {
      setMessage({ type: 'error', text: 'Network error while switching provider.' });
    } finally {
      setSwitchingProvider(null);
    }
  };

  useEffect(() => {
    if (activeTab === 'model-status') {
      fetchModelStatus(false);
      fetchCurrentProvider();
    }
  }, [activeTab, fetchModelStatus, fetchCurrentProvider]);

  useEffect(() => {
    setActiveTab(initialTab || 'profile');
  }, [initialTab]);

  const handleProfileSubmit = async (e) => {
    e.preventDefault();
    setMessage(null);
    if (!firstName.trim()) {
      setMessage({ type: 'error', text: 'First name is required.' });
      return;
    }
    if (!email.trim()) {
      setMessage({ type: 'error', text: 'Email is required.' });
      return;
    }
    setIsSubmitting(true);
    try {
      const payload = {
        firstName: firstName.trim(),
        lastName: lastName.trim(),
      };
      if (email.trim() !== (user?.email || '')) {
        payload.email = email.trim();
      }
      const response = await fetch(`${apiUrl}/auth/me`, {
        method: 'PATCH',
        headers: {
          'Content-Type': 'application/json',
          Authorization: `Bearer ${authToken}`,
        },
        body: JSON.stringify(payload),
      });
      const data = await response.json().catch(() => null);
      if (!response.ok) {
        setMessage({ type: 'error', text: extractError(data, 'Could not update profile.') });
        return;
      }
      onUserUpdate?.(data);
      setFirstName(data.firstName || '');
      setLastName(data.lastName || '');
      setEmail(data.email || '');
      setMessage({ type: 'success', text: 'Profile updated.' });
    } catch (err) {
      setMessage({ type: 'error', text: 'Network error. Please try again.' });
    } finally {
      setIsSubmitting(false);
    }
  };

  const handlePasswordSubmit = async (e) => {
    e.preventDefault();
    setMessage(null);
    if (newPassword !== confirmPassword) {
      setMessage({ type: 'error', text: 'New passwords do not match.' });
      return;
    }
    if (newPassword.length < 8) {
      setMessage({ type: 'error', text: 'New password must be at least 8 characters.' });
      return;
    }
    setIsSubmitting(true);
    try {
      const response = await fetch(`${apiUrl}/auth/me/password`, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          Authorization: `Bearer ${authToken}`,
        },
        body: JSON.stringify({
          current_password: currentPassword,
          new_password: newPassword,
        }),
      });
      const data = await response.json().catch(() => null);
      if (!response.ok) {
        setMessage({ type: 'error', text: extractError(data, 'Could not change password.') });
        return;
      }
      setCurrentPassword('');
      setNewPassword('');
      setConfirmPassword('');
      setMessage({ type: 'success', text: 'Password changed.' });
    } catch (err) {
      setMessage({ type: 'error', text: 'Network error. Please try again.' });
    } finally {
      setIsSubmitting(false);
    }
  };

  const handleDeleteAccount = async (e) => {
    e.preventDefault();
    setMessage(null);
    if (deleteConfirmText !== 'DELETE') {
      setMessage({ type: 'error', text: 'Type DELETE to confirm.' });
      return;
    }
    if (!deleteConfirmPassword) {
      setMessage({ type: 'error', text: 'Password required to delete account.' });
      return;
    }
    setIsSubmitting(true);
    try {
      const response = await fetch(`${apiUrl}/auth/me`, {
        method: 'DELETE',
        headers: {
          'Content-Type': 'application/json',
          Authorization: `Bearer ${authToken}`,
        },
        body: JSON.stringify({ password: deleteConfirmPassword }),
      });
      const data = await response.json().catch(() => null);
      if (!response.ok) {
        setMessage({ type: 'error', text: extractError(data, 'Could not delete account.') });
        return;
      }
      onClose?.();
      onSignOut?.();
    } catch (err) {
      setMessage({ type: 'error', text: 'Network error. Please try again.' });
    } finally {
      setIsSubmitting(false);
    }
  };

  const messageStyle = (type) => ({
    padding: '10px 12px', borderRadius: 8, marginBottom: 16, fontSize: 13,
    background: type === 'error'
      ? 'rgba(220,38,38,0.1)'
      : type === 'success'
        ? 'rgba(22,163,74,0.1)'
        : 'var(--bg-secondary)',
    color: type === 'error'
      ? '#dc2626'
      : type === 'success'
        ? '#16a34a'
        : 'var(--text-secondary)',
    border: `1px solid ${
      type === 'error'
        ? 'rgba(220,38,38,0.3)'
        : type === 'success'
          ? 'rgba(22,163,74,0.3)'
          : 'var(--border-primary)'
    }`,
  });

  const switchTab = (tab) => {
    setActiveTab(tab);
    setMessage(null);
  };

  return ReactDOM.createPortal(
    <div style={overlay} onMouseDown={handleOverlayMouseDown} onMouseUp={handleOverlayMouseUp}>
      <div style={modal}>
        <div style={header}>
          <h3 style={{ margin: 0, color: 'var(--text-primary)', fontSize: 18 }}>Account Settings</h3>
          <button onClick={onClose} style={{ background: 'none', border: 'none', cursor: 'pointer', color: 'var(--text-secondary)' }}>
            <X size={20} />
          </button>
        </div>

        <div style={tabRow}>
          <button style={tabBtn(activeTab === 'profile')} onClick={() => switchTab('profile')}>
            <UserIcon size={15} /> Profile
          </button>
          <button style={tabBtn(activeTab === 'password')} onClick={() => switchTab('password')}>
            <Lock size={15} /> Password
          </button>
          <button style={tabBtn(activeTab === 'danger')} onClick={() => switchTab('danger')}>
            <Trash2 size={15} /> Delete Account
          </button>
          <button style={tabBtn(activeTab === 'model-status')} onClick={() => switchTab('model-status')}>
            <Activity size={15} /> Model Status
          </button>
        </div>

        <div style={body}>
          {message && <div style={messageStyle(message.type)}>{message.text}</div>}

          {activeTab === 'profile' && (
            <form onSubmit={handleProfileSubmit}>
              <div style={{ marginBottom: 16 }}>
                <label style={label}>Email</label>
                {user?.is_guest ? (
                  <input style={{ ...input, opacity: 0.6, cursor: 'not-allowed' }} value={user?.email || ''} disabled />
                ) : (
                  <input type="email" style={input} value={email} onChange={(e) => setEmail(e.target.value)} />
                )}
              </div>
              <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 12, marginBottom: 16 }}>
                <div>
                  <label style={label}>First Name</label>
                  <input style={input} value={firstName} onChange={(e) => setFirstName(e.target.value)} />
                </div>
                <div>
                  <label style={label}>Last Name</label>
                  <input style={input} value={lastName} onChange={(e) => setLastName(e.target.value)} />
                </div>
              </div>
              <button type="submit" style={primaryBtn} disabled={isSubmitting}>
                {isSubmitting ? 'Saving…' : 'Save Changes'}
              </button>
            </form>
          )}

          {activeTab === 'password' && (
            <form onSubmit={handlePasswordSubmit}>
              <div style={{ marginBottom: 16 }}>
                <label style={label}>Current Password</label>
                <input type="password" style={input} value={currentPassword} onChange={(e) => setCurrentPassword(e.target.value)} required />
              </div>
              <div style={{ marginBottom: 16 }}>
                <label style={label}>New Password</label>
                <input type="password" style={input} value={newPassword} onChange={(e) => setNewPassword(e.target.value)} required />
              </div>
              <div style={{ marginBottom: 16 }}>
                <label style={label}>Confirm New Password</label>
                <input type="password" style={input} value={confirmPassword} onChange={(e) => setConfirmPassword(e.target.value)} required />
              </div>
              <button type="submit" style={primaryBtn} disabled={isSubmitting}>
                {isSubmitting ? 'Changing…' : 'Change Password'}
              </button>
            </form>
          )}

          {activeTab === 'danger' && (
            <form onSubmit={handleDeleteAccount}>
              <div style={{
                display: 'flex', gap: 10, padding: 12, borderRadius: 8,
                background: 'rgba(220,38,38,0.08)', border: '1px solid rgba(220,38,38,0.3)',
                marginBottom: 16,
              }}>
                <AlertTriangle size={18} style={{ color: '#dc2626', flexShrink: 0, marginTop: 2 }} />
                <div style={{ fontSize: 13, color: 'var(--text-primary)' }}>
                  Deleting your account is permanent. All chat history and personal data will be removed.
                </div>
              </div>
              <div style={{ marginBottom: 16 }}>
                <label style={label}>Confirm Password</label>
                <input type="password" style={input} value={deleteConfirmPassword} onChange={(e) => setDeleteConfirmPassword(e.target.value)} required />
              </div>
              <div style={{ marginBottom: 16 }}>
                <label style={label}>Type <strong>DELETE</strong> to confirm</label>
                <input style={input} value={deleteConfirmText} onChange={(e) => setDeleteConfirmText(e.target.value)} placeholder="DELETE" required />
              </div>
              <button type="submit" style={dangerBtn} disabled={isSubmitting}>
                {isSubmitting ? 'Deleting…' : 'Permanently Delete Account'}
              </button>
            </form>
          )}

          {activeTab === 'model-status' && (
            <div>
              <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: 16, gap: 12 }}>
                <div style={{ fontSize: 13, color: 'var(--text-secondary)' }}>
                  Probe each configured API with a tiny chat request.
                  {modelStatus?.cached ? ' Showing cached results.' : null}
                  {modelStatus?.checked_at ? (
                    <span> Last checked: {new Date(modelStatus.checked_at).toLocaleString()}</span>
                  ) : null}
                </div>
                <button
                  type="button"
                  style={{ ...primaryBtn, display: 'inline-flex', alignItems: 'center', gap: 8, flexShrink: 0 }}
                  onClick={() => fetchModelStatus(true)}
                  disabled={statusLoading}
                >
                  {statusLoading
                    ? <Loader2 size={15} className="spinning" style={{ animation: 'spin 1s linear infinite' }} />
                    : <RefreshCw size={15} />}
                  Refresh
                </button>
              </div>

              {statusError && (
                <div style={messageStyle('error')}>
                  Status check failed — provider list left unfiltered. {statusError}
                </div>
              )}

              {modelStatus?.check_failed && !statusError && (
                <div style={messageStyle('error')}>
                  Status check failed — provider list left unfiltered.
                  {modelStatus.error ? ` ${modelStatus.error}` : ''}
                </div>
              )}

              {statusLoading && !modelStatus?.models?.length && (
                <div style={{ color: 'var(--text-secondary)', fontSize: 13 }}>Checking models…</div>
              )}

              <div style={{ display: 'flex', flexDirection: 'column', gap: 10 }}>
                {(modelStatus?.models || []).map((m) => {
                  const tone = statusColors[m.status] || statusColors.unavailable;
                  const isActive = m.provider === currentProvider;
                  // Fail closed per model: only online + selectable providers can
                  // be activated. Fail open if the whole check failed (no rows
                  // render in that case, so nothing is blocked).
                  const canActivate = m.status === 'online' && m.selectable !== false && !isActive;
                  return (
                    <div
                      key={m.id}
                      style={{
                        padding: '12px 14px',
                        borderRadius: 10,
                        border: `1px solid ${isActive ? 'var(--accent-primary)' : tone.border}`,
                        background: 'var(--bg-secondary)',
                      }}
                    >
                      <div style={{ display: 'flex', justifyContent: 'space-between', gap: 12, alignItems: 'center', flexWrap: 'wrap' }}>
                        <div style={{ minWidth: 0 }}>
                          <div style={{ fontWeight: 600, color: 'var(--text-primary)', fontSize: 14 }}>
                            {m.name}
                            {m.model ? (
                              <span style={{ fontWeight: 400, color: 'var(--text-secondary)', marginLeft: 8, fontSize: 12 }}>
                                {m.model}
                              </span>
                            ) : null}
                          </div>
                          <div style={{ fontSize: 12, color: 'var(--text-secondary)', marginTop: 2 }}>
                            {m.provider}
                            {typeof m.latency_ms === 'number' ? ` · ${m.latency_ms} ms` : ''}
                          </div>
                        </div>
                        <div style={{ display: 'flex', alignItems: 'center', gap: 8, flexShrink: 0 }}>
                          <span style={{
                            fontSize: 12,
                            fontWeight: 600,
                            textTransform: 'uppercase',
                            letterSpacing: '0.03em',
                            padding: '4px 8px',
                            borderRadius: 6,
                            background: tone.bg,
                            color: tone.color,
                            border: `1px solid ${tone.border}`,
                          }}>
                            {m.status}
                          </span>
                          {isActive ? (
                            <span style={{
                              fontSize: 12,
                              fontWeight: 600,
                              padding: '4px 10px',
                              borderRadius: 6,
                              background: 'var(--accent-fill, var(--accent-primary))',
                              color: 'var(--accent-on-accent, #fff)',
                            }}>
                              Active
                            </span>
                          ) : (
                            <button
                              type="button"
                              onClick={() => handleProviderSwitch(m.provider)}
                              disabled={!canActivate || !!switchingProvider}
                              style={{
                                fontSize: 12,
                                fontWeight: 600,
                                padding: '4px 10px',
                                borderRadius: 6,
                                border: '1px solid var(--border-primary)',
                                background: 'transparent',
                                color: canActivate ? 'var(--accent-primary)' : 'var(--text-secondary)',
                                cursor: canActivate && !switchingProvider ? 'pointer' : 'not-allowed',
                                opacity: canActivate ? 1 : 0.5,
                              }}
                            >
                              {switchingProvider === m.provider ? 'Switching…' : 'Use'}
                            </button>
                          )}
                        </div>
                      </div>
                      {m.status === 'error' && m.error && (
                        <div style={{
                          marginTop: 8,
                          fontSize: 12,
                          color: '#dc2626',
                          wordBreak: 'break-word',
                          fontFamily: 'ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace',
                        }}>
                          {m.error}
                        </div>
                      )}
                    </div>
                  );
                })}
              </div>
            </div>
          )}
        </div>
      </div>
    </div>,
    document.body
  );
};

export default SettingsModal;