import { useState, useEffect, useCallback } from 'react';
import { useParams, useNavigate } from 'react-router-dom';
import apiClient from '../api/client';
import { useBusiness } from '../context/BusinessContext';

export default function GlobalSms() {
  const { businessId } = useParams();
  const navigate = useNavigate();
  const { isSetupComplete, setHasGlobalSms, setIsSetupComplete } = useBusiness();
  const [loading, setLoading] = useState(true);
  const [profiles, setProfiles] = useState([]);
  const [activeProfileId, setActiveProfileId] = useState(null);

  const [saving, setSaving] = useState(false);
  const [error, setError] = useState('');
  const [success, setSuccess] = useState('');

  // Form state for Create / Edit Profile
  const [editingId, setEditingId] = useState(null);
  const [formName, setFormName] = useState('');
  const [formCurl, setFormCurl] = useState('');
  const [formSetActive, setFormSetActive] = useState(true);

  // Form state for Missing Provider Fields
  const [providerForm, setProviderForm] = useState({ providerName: '', senderId: '', dltEntityId: '' });
  const [savingProvider, setSavingProvider] = useState(false);
  const eventsPath = `/${businessId}/events`;

  const loadProfiles = useCallback(async () => {
    try {
      setLoading(true);
      const res = await apiClient.get(`/api/businesses/${businessId}/global-sms/profiles`);
      const fetchedProfiles = res.data.profiles || [];
      const fetchActiveId = res.data.activeProfileId;
      setProfiles(fetchedProfiles);
      setActiveProfileId(fetchActiveId);

      const activeProfile = fetchedProfiles.find(p => p.id === fetchActiveId) || null;
      const hasProfile = !!activeProfile;
      setHasGlobalSms(hasProfile);

      const p = activeProfile?.provider || {};
      const complete = hasProfile && !!p.providerName && !!p.senderId && !!p.dltEntityId;
      setIsSetupComplete(complete);

      setProviderForm({
        providerName: p.providerName || '',
        senderId: p.senderId || '',
        dltEntityId: p.dltEntityId || '',
      });

      return { activeProfile, hasProfile, complete };
    } catch {
      setError('Failed to load cURL profiles');
      setHasGlobalSms(false);
      setIsSetupComplete(false);
      return { activeProfile: null, hasProfile: false, complete: false };
    } finally {
      setLoading(false);
    }
  }, [businessId, setHasGlobalSms, setIsSetupComplete]);

  useEffect(() => {
    loadProfiles();
  }, [loadProfiles]);

  const activeProfile = profiles.find(p => p.id === activeProfileId) || null;
  const pData = activeProfile?.provider || {};
  const missingFields = [];
  if (activeProfile && !pData.providerName) missingFields.push('providerName');
  if (activeProfile && !pData.senderId) missingFields.push('senderId');
  if (activeProfile && !pData.dltEntityId) missingFields.push('dltEntityId');

  function handleAddClick() {
    setEditingId(null);
    setFormName('');
    setFormCurl('');
    setFormSetActive(profiles.length === 0);
    setError('');
    setSuccess('');
  }

  function handleEditClick(profile) {
    setEditingId(profile.id);
    setFormName(profile.name);
    setFormCurl(profile.rawCurl);
    setFormSetActive(false);
    setError('');
    setSuccess('');
  }

  async function handleSubmit(e) {
    e.preventDefault();
    if (!formName.trim() || !formCurl.trim()) return;
    setSaving(true);
    setError('');
    setSuccess('');
    const shouldAutoAdvance = !isSetupComplete;

    try {
      if (editingId) {
        await apiClient.patch(`/api/businesses/${businessId}/global-sms/profiles/${editingId}`, {
          name: formName,
          rawCurl: formCurl,
        });
        setSuccess('Profile updated successfully.');
      } else {
        await apiClient.post(`/api/businesses/${businessId}/global-sms/profiles`, {
          name: formName,
          rawCurl: formCurl,
          setActive: formSetActive,
        });
        setSuccess('Profile created successfully.');
      }
      const nextState = await loadProfiles();
      setFormName('');
      setFormCurl('');
      setEditingId(null);
      if (shouldAutoAdvance && nextState.complete) {
        navigate(eventsPath);
      }
    } catch (err) {
      setError(err.response?.data?.error || 'Failed to save cURL profile');
    } finally {
      setSaving(false);
    }
  }

  async function handleDelete(id) {
    if (!window.confirm('Delete this cURL profile?')) return;
    try {
      await apiClient.delete(`/api/businesses/${businessId}/global-sms/profiles/${id}`);
      await loadProfiles();
    } catch (err) {
      setError(err.response?.data?.error || 'Failed to delete profile');
    }
  }

  async function handleActivate(id) {
    const shouldAutoAdvance = !isSetupComplete;
    try {
      await apiClient.post(`/api/businesses/${businessId}/global-sms/profiles/${id}/activate`);
      const nextState = await loadProfiles();
      if (shouldAutoAdvance && nextState.complete) {
        navigate(eventsPath);
      }
    } catch (err) {
      setError(err.response?.data?.error || 'Failed to activate profile');
    }
  }

  async function handleProviderSubmit(e) {
    e.preventDefault();
    if (!activeProfileId) return;
    setSavingProvider(true);
    setError('');
    setSuccess('');
    const shouldAutoAdvance = !isSetupComplete;

    try {
      await apiClient.patch(`/api/businesses/${businessId}/global-sms/profiles/${activeProfileId}`, {
        provider: {
          providerName: providerForm.providerName,
          senderId: providerForm.senderId.toUpperCase(),
          dltEntityId: providerForm.dltEntityId,
        }
      });
      setSuccess('Provider details saved successfully!');
      const nextState = await loadProfiles();
      if (shouldAutoAdvance && nextState.complete) {
        navigate(eventsPath);
      }
    } catch (err) {
      setError(err.response?.data?.error || 'Failed to save provider details');
    } finally {
      setSavingProvider(false);
    }
  }

  if (loading) {
    return (
      <div className="flex h-64 items-center justify-center">
        <span className="w-8 h-8 border-4 border-spinner-track border-t-primary-blue rounded-full animate-spin" />
      </div>
    );
  }

  return (
    <div className="max-w-4xl mx-auto space-y-8 pb-12">
      <div>
        <h2 className="text-2xl font-bold text-text-primary mb-2">Omni-channel SMS</h2>
        <p className="text-sm text-text-muted">
          Complete this flow to configure your cURL profile and brand provider data. You must finish setup before generating templates.
        </p>
      </div>

      {error && (
        <div className="px-4 py-3 rounded-md bg-delayed-bg border border-delayed-border text-error-text text-sm font-medium flex justify-between items-center">
          {error}
          <button onClick={() => setError('')} className="text-error-text hover:text-red-900 font-bold">&times;</button>
        </div>
      )}
      {success && (
        <div className="px-4 py-3 rounded-md bg-badge-bg border border-badge-border text-badge-text text-sm font-medium flex justify-between items-center">
          {success}
          <button onClick={() => setSuccess('')} className="text-badge-text hover:opacity-75 font-bold">&times;</button>
        </div>
      )}

      {/* Active Profile Setup Review Block */}
      {activeProfile && (
        <div className={`p-6 rounded-lg border ${isSetupComplete ? 'border-primary-blue bg-refresh-hover' : 'border-tags-border bg-tags-bg'} shadow-sm`}>
          <div className="flex items-center gap-3 mb-4">
            <h3 className="font-bold text-text-primary text-lg">Active Setup: {activeProfile.name}</h3>
            {isSetupComplete ? (
              <span className="px-3 py-1 bg-badge-bg text-badge-text border border-badge-border rounded-full text-xs font-bold uppercase tracking-wide">Setup Complete</span>
            ) : (
              <span className="px-3 py-1 bg-tags-bg text-tags-text border border-tags-border rounded-full text-xs font-bold uppercase tracking-wide">Missing Information</span>
            )}
          </div>

          <div className="grid md:grid-cols-2 gap-6">
            <div className="space-y-3">
              <p className="text-sm font-medium text-text-primary">Parsed Provider Data:</p>
              <ul className="space-y-2 text-sm">
                <li className="flex justify-between items-center bg-surface-white p-2 rounded border border-border-soft">
                  <span className="text-text-muted">Provider:</span>
                  <span className="font-bold text-text-primary">{pData.providerName || <span className="text-error-text text-xs uppercase">Missing</span>}</span>
                </li>
                <li className="flex justify-between items-center bg-surface-white p-2 rounded border border-border-soft">
                  <span className="text-text-muted">Sender ID:</span>
                  <span className="font-bold text-text-primary">{pData.senderId || <span className="text-error-text text-xs uppercase">Missing</span>}</span>
                </li>
                <li className="flex justify-between items-center bg-surface-white p-2 rounded border border-border-soft">
                  <span className="text-text-muted">Entity ID:</span>
                  <span className="font-bold text-text-primary">{pData.dltEntityId || <span className="text-error-text text-xs uppercase">Missing</span>}</span>
                </li>
                <li className="flex justify-between items-center bg-surface-white p-2 rounded border border-border-soft">
                  <span className="text-text-muted">Auth Key:</span>
                  <span className="font-semibold text-text-primary font-mono">{pData.authKey ? '••••••••' : 'None setup'}</span>
                </li>
              </ul>
            </div>

            {!isSetupComplete && (
              <div className="bg-surface-white p-4 rounded-lg border border-border-main shadow-sm">
                <p className="text-sm font-semibold text-text-primary mb-3">Please fill in the missing fields:</p>
                <form onSubmit={handleProviderSubmit} className="space-y-3">
                  {missingFields.includes('providerName') && (
                    <input
                      type="text"
                      placeholder="Provider Name (e.g. MSG91)"
                      value={providerForm.providerName}
                      onChange={e => setProviderForm({ ...providerForm, providerName: e.target.value })}
                      className="w-full px-3 py-2 border border-border-main rounded text-sm focus:ring-1 focus:ring-primary-blue bg-page-bg"
                      required
                    />
                  )}
                  {missingFields.includes('senderId') && (
                    <input
                      type="text"
                      placeholder="Sender ID (6 letters)"
                      maxLength={6}
                      value={providerForm.senderId}
                      onChange={e => setProviderForm({ ...providerForm, senderId: e.target.value.toUpperCase() })}
                      className="w-full px-3 py-2 border border-border-main rounded text-sm focus:ring-1 focus:ring-primary-blue bg-page-bg uppercase"
                      required
                    />
                  )}
                  {missingFields.includes('dltEntityId') && (
                    <input
                      type="text"
                      placeholder="19-digit DLT PE ID"
                      value={providerForm.dltEntityId}
                      onChange={e => setProviderForm({ ...providerForm, dltEntityId: e.target.value })}
                      className="w-full px-3 py-2 border border-border-main rounded text-sm focus:ring-1 focus:ring-primary-blue bg-page-bg"
                      required
                    />
                  )}
                  <button
                    type="submit"
                    disabled={savingProvider}
                    className="w-full py-2 bg-primary-blue hover:bg-primary-dark text-white text-sm font-bold rounded shadow-sm transition disabled:opacity-50"
                  >
                    {savingProvider ? 'Saving...' : 'Save Required Details'}
                  </button>
                </form>
              </div>
            )}

            {isSetupComplete && (
              <div className="flex flex-col justify-center items-center h-full space-y-4">
                <p className="text-center text-sm font-medium text-text-muted">Your active cURL profile is fully configured.</p>
                <button
                  onClick={() => navigate(eventsPath)}
                  className="px-6 py-3 bg-primary-blue hover:bg-primary-dark text-white rounded-lg shadow font-semibold text-sm transition w-full"
                >
                  Continue to Events →
                </button>
              </div>
            )}
          </div>
        </div>
      )}

      {/* Profiles List */}
      <div className="space-y-4 pt-4 border-t border-border-soft">
        <h3 className="font-bold text-text-primary text-lg">All Profiles</h3>
        {profiles.length > 0 ? (
          profiles.map(p => {
            const isActive = p.id === activeProfileId;
            return (
              <div key={p.id} className={`p-5 rounded-lg border ${isActive ? 'border-primary-blue bg-refresh-hover' : 'border-border-main bg-surface-white'} shadow-sm flex flex-col md:flex-row gap-4 items-start md:items-center justify-between transition-colors`}>
                <div className="flex-1 overflow-hidden">
                  <div className="flex items-center gap-3 mb-1">
                    <h3 className="font-bold text-text-primary text-base truncate">{p.name}</h3>
                    {isActive && (
                      <span className="px-2 py-0.5 rounded text-[11px] font-bold tracking-wider uppercase bg-badge-bg text-badge-text border border-badge-border shrink-0">
                        Active Profile
                      </span>
                    )}
                    {p.isDefault && !isActive && (
                      <span className="px-2 py-0.5 rounded text-[11px] font-bold tracking-wider uppercase bg-tags-bg text-tags-text border border-tags-border shrink-0">
                        Default
                      </span>
                    )}
                  </div>
                  <p className="text-xs text-text-muted font-medium mb-2">Updated: {new Date(p.updatedAt).toLocaleString()}</p>
                  <p className="text-sm font-mono text-text-muted bg-page-bg p-2 rounded border border-border-soft overflow-hidden whitespace-nowrap text-ellipsis max-w-xl">
                    {p.rawCurl}
                  </p>
                </div>
                <div className="flex items-center gap-2 shrink-0">
                  {!isActive && (
                    <button
                      onClick={() => handleActivate(p.id)}
                      className="px-4 py-2 bg-primary-blue hover:bg-primary-dark text-white text-sm font-semibold rounded-lg shadow-sm transition"
                    >
                      Use this cURL
                    </button>
                  )}
                  <button
                    onClick={() => handleEditClick(p)}
                    className="px-3 py-2 border border-border-main text-text-muted hover:text-primary-blue hover:border-primary-blue rounded-lg text-sm font-medium transition"
                  >
                    Edit
                  </button>
                  {profiles.length > 1 && (
                    <button
                      onClick={() => handleDelete(p.id)}
                      className="px-3 py-2 border border-border-main text-text-muted hover:text-error-text hover:border-error-text hover:bg-delayed-bg rounded-lg text-sm font-medium transition"
                    >
                      Delete
                    </button>
                  )}
                </div>
              </div>
            );
          })
        ) : (
          <div className="text-center py-12 bg-surface-white border border-border-main border-dashed rounded-lg">
            <p className="text-sm font-medium text-text-muted mb-4">No cURL profiles configured yet.</p>
          </div>
        )}
      </div>

      {/* Inline Form (Create / Edit) */}
      <div className="bg-surface-white border border-border-main rounded-lg shadow-sm overflow-hidden">
        <div className="px-6 py-4 border-b border-border-main bg-table-header flex items-center justify-between">
          <h3 className="font-bold text-text-primary text-md">
            {editingId ? 'Edit Profile' : 'Add New Profile'}
          </h3>
          {editingId && (
            <button onClick={handleAddClick} className="text-sm font-semibold text-primary-blue hover:underline">
              Switch to Add New
            </button>
          )}
        </div>
        <div className="p-6">
          <form onSubmit={handleSubmit} className="space-y-5">
            <div>
              <label className="block text-sm font-semibold text-text-primary mb-1.5">Profile Name</label>
              <input
                type="text"
                value={formName}
                onChange={e => setFormName(e.target.value)}
                placeholder="e.g. Production SMS, Staging Twilio"
                className="w-full px-4 py-2.5 rounded-lg bg-page-bg border border-border-main text-text-primary placeholder-placeholder-bg focus:outline-none focus:ring-2 focus:ring-primary-blue transition text-sm"
                required
              />
            </div>
            <div>
              <label className="block text-sm font-semibold text-text-primary mb-1.5">Raw cURL Command</label>
              <textarea
                value={formCurl}
                onChange={e => setFormCurl(e.target.value)}
                placeholder="curl --request POST --url ..."
                className="w-full h-40 px-4 py-3 rounded-lg font-mono text-sm bg-page-bg border border-border-main text-text-primary placeholder-placeholder-bg focus:outline-none focus:ring-2 focus:ring-primary-blue transition resize-none leading-relaxed"
                required
                spellCheck="false"
              />
            </div>
            {!editingId && profiles.length > 0 && (
              <label className="flex items-center gap-2 cursor-pointer">
                <input
                  type="checkbox"
                  className="w-4 h-4 text-primary-blue rounded border-border-main focus:ring-primary-blue"
                  checked={formSetActive}
                  onChange={e => setFormSetActive(e.target.checked)}
                />
                <span className="text-sm font-semibold text-text-primary">Set as active profile immediately</span>
              </label>
            )}
            <div className="flex gap-3 pt-2">
              <button
                type="submit"
                disabled={saving}
                className="px-6 py-2.5 rounded-lg bg-primary-blue hover:bg-primary-dark text-white font-semibold text-sm shadow-sm transition disabled:opacity-50 flex items-center justify-center gap-2"
              >
                {saving ? <><span className="w-4 h-4 border-2 border-white/30 border-t-white rounded-full animate-spin" /> Saving…</> : (editingId ? 'Update Profile' : 'Save Profile')}
              </button>
              {editingId && (
                <button
                  type="button"
                  onClick={handleAddClick}
                  disabled={saving}
                  className="px-5 py-2.5 rounded-lg border border-border-main text-text-primary hover:bg-page-bg font-medium text-sm transition"
                >
                  Cancel Edit
                </button>
              )}
            </div>
          </form>
        </div>
      </div>
    </div>
  );
}