import { useState } from 'react';
import { Cloud, ChevronDown, ChevronRight } from 'lucide-react';

export default function ComparisonSelector({ providers, selected, onSelectionChange }) {
  const [expandedProviders, setExpandedProviders] = useState({});

  const toggleExpand = (providerId) => {
    setExpandedProviders(prev => ({ ...prev, [providerId]: !prev[providerId] }));
  };

  const toggleModel = (modelId) => {
    if (selected.includes(modelId)) {
      onSelectionChange(selected.filter(id => id !== modelId));
    } else {
      onSelectionChange([...selected, modelId]);
    }
  };

  const toggleProvider = (provider) => {
    const providerModelIds = provider.models.map(m => m.id);
    const allSelected = providerModelIds.every(id => selected.includes(id));
    if (allSelected) {
      onSelectionChange(selected.filter(id => !providerModelIds.includes(id)));
    } else {
      const newIds = providerModelIds.filter(id => !selected.includes(id));
      onSelectionChange([...selected, ...newIds]);
    }
  };

  if (!providers.length) {
    return (
      <div className="selector-section">
        <h3 className="selector-title"><Cloud size={16} /> Comparison Models</h3>
        <p className="selector-hint">Configure API keys in .env to enable comparison providers</p>
      </div>
    );
  }

  return (
    <div className="selector-section">
      <h3 className="selector-title"><Cloud size={16} /> Comparison Models</h3>
      <p className="selector-hint">Select models to compare against</p>
      <div className="comparison-providers">
        {[...providers].sort((a, b) => a.name.localeCompare(b.name)).map(provider => {
          const providerModelIds = provider.models.map(m => m.id);
          const allSelected = providerModelIds.every(id => selected.includes(id));
          const selectedCount = providerModelIds.filter(id => selected.includes(id)).length;
          const isExpanded = expandedProviders[provider.id] === true;
          return (
            <div key={provider.id} className="comparison-provider-group">
              <div className="provider-group-header">
                <label className="provider-group-checkbox" onClick={(e) => e.stopPropagation()}>
                  <input
                    type="checkbox"
                    checked={allSelected}
                    onChange={() => toggleProvider(provider)}
                  />
                </label>
                <button className="provider-group-toggle" onClick={() => toggleExpand(provider.id)}>
                  <span className="provider-group-name">{provider.name}</span>
                  {selectedCount > 0 && <span className="provider-selected-count">{selectedCount}</span>}
                  {isExpanded ? <ChevronDown size={14} /> : <ChevronRight size={14} />}
                </button>
              </div>
              {isExpanded && (
                <div className="provider-model-list">
                  {provider.models.map(model => (
                    <label key={model.id} className={`comparison-model-item ${selected.includes(model.id) ? 'selected' : ''}`}>
                      <input
                        type="checkbox"
                        checked={selected.includes(model.id)}
                        onChange={() => toggleModel(model.id)}
                      />
                      <span className="comparison-model-name">{model.name}</span>
                    </label>
                  ))}
                </div>
              )}
            </div>
          );
        })}
      </div>

      <style>{`
        .comparison-providers {
          display: flex;
          flex-direction: column;
          gap: 10px;
        }
        .comparison-provider-group {
          border: 1px solid var(--border-primary);
          border-radius: 8px;
          overflow: hidden;
          background: #E0EAFD;
        }
        :root[data-theme="dark"] .comparison-provider-group {
          background: #1E2A40;
        }
        .provider-group-header {
          display: flex;
          align-items: center;
          gap: 8px;
          padding: 8px 12px;
          font-size: 13px;
          border-bottom: 1px solid var(--border-muted);
        }
        .provider-group-checkbox {
          display: flex;
          align-items: center;
          cursor: pointer;
        }
        .provider-group-checkbox input[type="checkbox"] {
          accent-color: var(--accent-primary);
          box-shadow: 0 1px 6px 1px rgba(0, 0, 0, 0.3);
          border-radius: 3px;
        }
        .provider-group-toggle {
          display: flex;
          align-items: center;
          gap: 6px;
          flex: 1;
          background: none;
          border: none;
          color: var(--text-primary);
          font-size: 13px;
          cursor: pointer;
          padding: 0;
          text-align: left;
        }
        .provider-group-toggle:hover {
          opacity: 0.8;
        }
        .provider-selected-count {
          font-size: 11px;
          font-weight: 600;
          color: var(--accent-primary);
          background: var(--accent-light);
          padding: 1px 6px;
          border-radius: 10px;
          margin-left: auto;
        }
        .provider-model-list {
          padding: 4px;
        }
        .comparison-model-item {
          display: flex;
          align-items: center;
          gap: 8px;
          padding: 6px 8px;
          border-radius: 6px;
          cursor: pointer;
          transition: background 0.15s;
          font-size: 13px;
        }
        .comparison-model-item:hover {
          background: var(--card-hover);
        }
        .comparison-model-item.selected {
          background: var(--accent-light);
        }
        .comparison-model-item input[type="checkbox"] {
          accent-color: var(--accent-primary);
        }
        .provider-group-name {
          font-weight: 600;
          color: var(--text-primary);
          font-size: 13px;
          text-transform: uppercase;
        }
        .comparison-model-name {
          color: var(--text-primary);
        }
      `}</style>
    </div>
  );
}