"use client";

import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { Label } from "@/components/ui/label";
import { Card, CardContent } from "@/components/ui/card";
import { Trash, PlusCircle, Info } from "lucide-react";
import { useState } from "react";

interface PricingTiersProps {
  pricing: any[];
  handleTierChange: (
    e: React.ChangeEvent<HTMLInputElement>,
    index: number
  ) => void;
  handleRemoveTier: (index: number) => void;
  handleAddTier: () => void;
}

export const PricingTiers = ({
  pricing,
  handleTierChange,
  handleRemoveTier, 
  handleAddTier,
}: PricingTiersProps) => {
  const [showHelp, setShowHelp] = useState(false);

  const formatNumber = (num: number) => {
    if (num === 0) return "";
    return num % 1 === 0 ? num.toString() : num.toFixed(2);
  };

  const calculateTotal = (quantity: number, pricePerUnit: number) => {
    return (quantity * pricePerUnit).toFixed(2);
  };

  const validateTier = (tier: any, index: number) => {
    const errors = [];
    
    if (tier.minQuantity <= 0) {
      errors.push("Quantity must be greater than 0");
    }
    
    if (tier.pricePerUnit <= 0) {
      errors.push("Price must be greater than 0");
    }
    
    // Check for duplicate quantities
    const duplicateIndex = pricing.findIndex((p, i) => 
      i !== index && p.minQuantity === tier.minQuantity
    );
    
    if (duplicateIndex !== -1) {
      errors.push("Duplicate quantity found");
    }
    
    return errors;
  };

  const sortedPricing = [...pricing].sort((a, b) => a.minQuantity - b.minQuantity);

  return (
    <div className="space-y-4">
      <div className="flex items-center justify-between">
        <h3 className="text-sm font-medium">Pricing Tiers</h3>
        <Button
          variant="ghost"
          size="sm"
          onClick={() => setShowHelp(!showHelp)}
          className="text-xs text-muted-foreground"
        >
          <Info className="w-3 h-3 mr-1" />
          {showHelp ? "Hide" : "Help"}
        </Button>
      </div>

      {showHelp && (
        <Card className="bg-blue-50 border-blue-200">
          <CardContent className="p-3">
            <p className="text-xs text-blue-800">
              <strong>How it works:</strong> Set different prices based on quantity. 
              For example: 1-10 units at £5 each, 11-50 units at £4 each, 51+ units at £3 each.
              Quantities should be in ascending order.
            </p>
          </CardContent>
        </Card>
      )}

      {pricing?.length > 0 ? (
        <div className="space-y-3">
          {sortedPricing.map((tier, sortedIndex) => {
            const originalIndex = pricing.findIndex(p => p === tier);
            const errors = validateTier(tier, originalIndex);
            const total = tier.minQuantity && tier.pricePerUnit 
              ? calculateTotal(tier.minQuantity, tier.pricePerUnit)
              : "0.00";

            return (
              <Card key={tier._id || originalIndex} className={`p-4 ${errors.length > 0 ? 'border-red-200 bg-red-50' : 'border-gray-200'}`}>
                <div className="grid grid-cols-1 md:grid-cols-3 gap-4">
                  <div className="space-y-2">
                    <Label htmlFor={`quantity-${originalIndex}`} className="text-xs font-medium">
                      Minimum Quantity *
                    </Label>
                    <Input
                      id={`quantity-${originalIndex}`}
                      name="minQuantity"
                      type="number"
                      min="1"
                      step="1"
                      placeholder="e.g. 10"
                      value={tier.minQuantity === 0 ? "" : tier.minQuantity}
                      onChange={(e) => handleTierChange(e, originalIndex)}
                      className={`h-10 ${errors.some(e => e.includes('Quantity')) ? 'border-red-500' : ''}`}
                    />
                    {errors.some(e => e.includes('Quantity')) && (
                      <p className="text-xs text-red-600">{errors.find(e => e.includes('Quantity'))}</p>
                    )}
                  </div>

                  <div className="space-y-2">
                    <Label htmlFor={`price-${originalIndex}`} className="text-xs font-medium">
                      Price Per Unit (£) *
                    </Label>
                    <Input
                      id={`price-${originalIndex}`}
                      name="pricePerUnit"
                      type="number"
                      min="0"
                      step="0.01"
                      placeholder="e.g. 5.00"
                      value={tier.pricePerUnit === 0 ? "" : formatNumber(tier.pricePerUnit)}
                      onChange={(e) => handleTierChange(e, originalIndex)}
                      className={`h-10 ${errors.some(e => e.includes('Price')) ? 'border-red-500' : ''}`}
                    />
                    {errors.some(e => e.includes('Price')) && (
                      <p className="text-xs text-red-600">{errors.find(e => e.includes('Price'))}</p>
                    )}
                  </div>

                  <div className="space-y-2">
                    <Label className="text-xs font-medium text-muted-foreground">
                      Total Price
                    </Label>
                    <div className="h-10 px-3 py-2 bg-gray-50 border border-gray-200 rounded-md flex items-center">
                      <span className="text-sm font-medium">£{total}</span>
                    </div>
                    <p className="text-xs text-muted-foreground">
                      {tier.minQuantity} × £{formatNumber(tier.pricePerUnit)}
                    </p>
                  </div>
                </div>

                {errors.some(e => e.includes('Duplicate')) && (
                  <p className="text-xs text-red-600 mt-2">
                    ⚠️ This quantity is already used in another tier
                  </p>
                )}

                <div className="flex justify-end mt-3">
                  <Button
                    variant="ghost"
                    size="sm"
                    onClick={() => handleRemoveTier(originalIndex)}
                    className="text-red-600 hover:text-red-700 hover:bg-red-100"
                  >
                    <Trash className="w-4 h-4 mr-1" />
                    Remove
                  </Button>
                </div>
              </Card>
            );
          })}
        </div>
      ) : (
        <Card className="border-dashed border-2 border-gray-300">
          <CardContent className="p-6 text-center">
            <p className="text-sm text-gray-500 mb-2">No pricing tiers added yet</p>
            <p className="text-xs text-gray-400">Add your first tier to get started</p>
          </CardContent>
        </Card>
      )}

      <Button 
        variant="outline" 
        onClick={handleAddTier}
        className="w-full"
      >
        <PlusCircle className="w-4 h-4 mr-2" />
        Add Pricing Tier
      </Button>
    </div>
  );
};