/**
 * Shared Model Selector Component
 * Provides consistent model selection UI with search, badges, and proper scrolling
 */

import { useState, useRef, useMemo } from 'react';
import { cn } from '@cloudflare/kumo';
import { Check, ChevronDown, Search } from 'lucide-react';
import { Button } from '@/components/ui/button';
import { Badge } from '@/components/ui/badge';
import { Label } from '@/components/ui/label';
import { Input } from '@/components/ui/input';
import { Popover, PopoverContent, PopoverTrigger } from '@/components/ui/popover';

interface ModelOption {
  value: string;
  label: string;
  provider: string;
  hasUserKey: boolean;
  byokAvailable: boolean;
}

interface ModelSelectorProps {
  value: string;
  onValueChange: (value: string) => void;
  availableModels: ModelOption[];
  placeholder: string;
  label: string;
  systemDefault?: string;
  includeDefaultOption?: boolean;
  disabled?: boolean;
  className?: string;
}

// Helper to get clean model display name
const getModelDisplayName = (model: string): string => {
  return model || '';
};

export function ModelSelector({
  value,
  onValueChange,
  availableModels,
  placeholder,
  label,
  systemDefault,
  includeDefaultOption = false,
  disabled = false,
  className,
}: ModelSelectorProps) {
  const [open, setOpen] = useState(false);
  const [search, setSearch] = useState('');
  const listRef = useRef<HTMLDivElement>(null);

  // Filter models based on search
  const filteredModels = useMemo(() => {
    if (!search) return availableModels;
    return availableModels.filter(model =>
      model.label.toLowerCase().includes(search.toLowerCase())
    );
  }, [availableModels, search]);

  // Get display name for selected value
  const getSelectedDisplay = () => {
    if (value === 'default' && includeDefaultOption) {
      return 'Use default';
    }
    if (value && value !== 'default') {
      const selectedModel = availableModels.find((model) => model.value === value);
      return selectedModel?.label || value;
    }
    return '';
  };

  // Enhanced model classification for badges
  const getModelBadge = (model: ModelOption) => {
    // If model has a specific provider (not platform-only)
    if (model.provider && model.provider !== '') {
      if (model.hasUserKey) {
        return (
          <Badge variant="default" className="text-xs">
            BYOK
          </Badge>
        );
      } else {
        return (
          <Badge variant="outline" className="text-xs">
            Key needed
          </Badge>
        );
      }
    } else {
      // Platform model
      return (
        <Badge variant="secondary" className="text-xs">
          Platform
        </Badge>
      );
    }
  };

  return (
    <div className={cn('space-y-2', className)}>
      <Label className="text-sm font-medium">{label}</Label>
      <Popover open={open} onOpenChange={setOpen}>
        <PopoverTrigger asChild>
          <Button
            variant="outline"
            role="combobox"
            aria-expanded={open}
            className="w-full justify-between"
            disabled={disabled}
          >
            <span className="truncate">{getSelectedDisplay() || placeholder}</span>
            <ChevronDown className="ml-2 h-4 w-4 shrink-0 opacity-50" />
          </Button>
        </PopoverTrigger>
        <PopoverContent className="w-full p-0" style={{ width: 'var(--radix-popover-trigger-width)' }}>
          {/* Search Input */}
          <div className="flex items-center border-b px-3 py-2">
            <Search className="mr-2 h-4 w-4 shrink-0 text-text-tertiary" />
            <Input
              placeholder="Search models..."
              value={search}
              onChange={(e) => setSearch(e.target.value)}
              className="h-8 border-0 bg-transparent p-0 placeholder:text-text-tertiary focus-visible:outline-none focus-visible:ring-0 focus-visible:ring-offset-0"
            />
          </div>

          {/* Scrollable List */}
          <div
            ref={listRef}
            className="max-h-[300px] overflow-y-auto p-1 scroll-smooth"
            onWheel={(e) => {
              // Ensure wheel events are properly handled
              e.stopPropagation();
            }}
          >
            {/* No results */}
            {filteredModels.length === 0 && !includeDefaultOption && (
              <div className="py-6 text-center text-sm text-text-tertiary">
                No models found.
              </div>
            )}

            {/* Default option if requested */}
            {includeDefaultOption && (
              <div
                key="default"
                onClick={() => {
                  onValueChange('default');
                  setOpen(false);
                  setSearch('');
                }}
                className={cn(
                  "relative flex cursor-pointer select-none items-center justify-between rounded-sm px-2 py-1.5 text-sm outline-none transition-colors hover:bg-brand hover:text-text-secondary focus:bg-brand focus:text-text-secondary",
                  value === 'default' && "bg-brand text-text-secondary"
                )}
              >
                <div className="flex items-center gap-2">
                  <Check
                    className={cn(
                      "h-4 w-4 text-text-primary",
                      value === 'default' ? "opacity-100" : "opacity-0"
                    )}
                  />
                  <span className="font-medium">Use default</span>
                </div>
              </div>
            )}

            {/* Available models */}
            {filteredModels.map((model) => (
              <div
                key={model.value}
                onClick={() => {
                  onValueChange(model.value);
                  setOpen(false);
                  setSearch('');
                }}
                className={cn(
                  "relative flex cursor-pointer select-none items-center justify-between rounded-sm px-2 py-1.5 text-sm outline-none transition-colors hover:bg-brand hover:text-text-secondary focus:bg-brand focus:text-text-secondary",
                  value === model.value && "bg-brand text-text-secondary"
                )}
              >
                <div className="flex items-center gap-2 min-w-0 flex-1">
                  <Check
                    className={cn(
                      "h-4 w-4 text-text-primary shrink-0",
                      value === model.value ? "opacity-100" : "opacity-0"
                    )}
                  />
                  <span className="truncate">{model.label}</span>
                </div>
                <div className="flex items-center gap-1 ml-2 shrink-0">
                  {getModelBadge(model)}
                </div>
              </div>
            ))}
          </div>
        </PopoverContent>
      </Popover>

      {/* System default display */}
      {systemDefault && (
        <p className="text-xs text-text-tertiary truncate">
          🔧 System default: {getModelDisplayName(systemDefault)}
        </p>
      )}
    </div>
  );
}