"use client";

import * as React from "react";
import { useState, useRef, useEffect, useCallback } from "react";
import { cn } from "@/lib/utils";
import { Input } from "./input";
import { Check, ChevronDown } from "lucide-react";

interface CategoryAutocompleteProps {
  value: string;
  onChange: (value: string) => void;
  suggestions: string[];
  placeholder?: string;
  className?: string;
  disabled?: boolean;
  "data-testid"?: string;
}

export function CategoryAutocomplete({
  value,
  onChange,
  suggestions,
  placeholder = "Select or type a category...",
  className,
  disabled = false,
  "data-testid": testId,
}: CategoryAutocompleteProps) {
  const [isOpen, setIsOpen] = useState(false);
  const [inputValue, setInputValue] = useState(value);
  const [filteredSuggestions, setFilteredSuggestions] = useState<string[]>([]);
  const [highlightedIndex, setHighlightedIndex] = useState(-1);
  const containerRef = useRef<HTMLDivElement>(null);
  const inputRef = useRef<HTMLInputElement>(null);
  const listRef = useRef<HTMLUListElement>(null);

  // Update internal state when value prop changes
  useEffect(() => {
    setInputValue(value);
  }, [value]);

  // Filter suggestions based on input
  useEffect(() => {
    const searchTerm = inputValue.toLowerCase().trim();
    if (searchTerm === "") {
      setFilteredSuggestions(suggestions);
    } else {
      const filtered = suggestions.filter((s) =>
        s.toLowerCase().includes(searchTerm)
      );
      setFilteredSuggestions(filtered);
    }
    setHighlightedIndex(-1);
  }, [inputValue, suggestions]);

  // Close dropdown when clicking outside
  useEffect(() => {
    const handleClickOutside = (event: MouseEvent) => {
      if (
        containerRef.current &&
        !containerRef.current.contains(event.target as Node)
      ) {
        setIsOpen(false);
      }
    };

    document.addEventListener("mousedown", handleClickOutside);
    return () => document.removeEventListener("mousedown", handleClickOutside);
  }, []);

  // Scroll highlighted item into view
  useEffect(() => {
    if (highlightedIndex >= 0 && listRef.current) {
      const items = listRef.current.querySelectorAll("li");
      const highlightedItem = items[highlightedIndex];
      if (highlightedItem) {
        highlightedItem.scrollIntoView({ block: "nearest" });
      }
    }
  }, [highlightedIndex]);

  const handleInputChange = useCallback(
    (e: React.ChangeEvent<HTMLInputElement>) => {
      const newValue = e.target.value;
      setInputValue(newValue);
      onChange(newValue);
      setIsOpen(true);
    },
    [onChange]
  );

  const handleSelect = useCallback(
    (suggestion: string) => {
      setInputValue(suggestion);
      onChange(suggestion);
      setIsOpen(false);
      inputRef.current?.focus();
    },
    [onChange]
  );

  const handleKeyDown = useCallback(
    (e: React.KeyboardEvent) => {
      if (!isOpen) {
        if (e.key === "ArrowDown" || e.key === "Enter") {
          e.preventDefault();
          setIsOpen(true);
        }
        return;
      }

      switch (e.key) {
        case "ArrowDown":
          e.preventDefault();
          setHighlightedIndex((prev) =>
            prev < filteredSuggestions.length - 1 ? prev + 1 : prev
          );
          break;
        case "ArrowUp":
          e.preventDefault();
          setHighlightedIndex((prev) => (prev > 0 ? prev - 1 : -1));
          break;
        case "Enter":
          e.preventDefault();
          if (highlightedIndex >= 0 && filteredSuggestions[highlightedIndex]) {
            handleSelect(filteredSuggestions[highlightedIndex]);
          } else {
            setIsOpen(false);
          }
          break;
        case "Escape":
          e.preventDefault();
          setIsOpen(false);
          break;
        case "Tab":
          setIsOpen(false);
          break;
      }
    },
    [isOpen, highlightedIndex, filteredSuggestions, handleSelect]
  );

  const handleFocus = useCallback(() => {
    setIsOpen(true);
  }, []);

  return (
    <div ref={containerRef} className={cn("relative", className)}>
      <div className="relative">
        <Input
          ref={inputRef}
          value={inputValue}
          onChange={handleInputChange}
          onKeyDown={handleKeyDown}
          onFocus={handleFocus}
          placeholder={placeholder}
          disabled={disabled}
          data-testid={testId}
          className="pr-8"
        />
        <button
          type="button"
          className={cn(
            "absolute right-2 top-1/2 -translate-y-1/2 text-muted-foreground hover:text-foreground transition-colors",
            disabled && "pointer-events-none opacity-50"
          )}
          onClick={() => setIsOpen(!isOpen)}
          tabIndex={-1}
        >
          <ChevronDown
            className={cn(
              "h-4 w-4 transition-transform duration-200",
              isOpen && "rotate-180"
            )}
          />
        </button>
      </div>

      {isOpen && filteredSuggestions.length > 0 && (
        <ul
          ref={listRef}
          className="absolute z-50 mt-1 w-full max-h-60 overflow-auto rounded-md border bg-background p-1 shadow-md animate-in fade-in-0 zoom-in-95"
          role="listbox"
          data-testid="category-autocomplete-list"
        >
          {filteredSuggestions.map((suggestion, index) => (
            <li
              key={suggestion}
              role="option"
              aria-selected={highlightedIndex === index}
              className={cn(
                "relative flex cursor-pointer select-none items-center rounded-sm px-2 py-1.5 text-sm outline-none transition-colors",
                highlightedIndex === index && "bg-accent text-accent-foreground",
                inputValue === suggestion && "font-medium"
              )}
              onMouseDown={(e) => {
                e.preventDefault();
                handleSelect(suggestion);
              }}
              onMouseEnter={() => setHighlightedIndex(index)}
              data-testid={`category-option-${suggestion.toLowerCase().replace(/\s+/g, "-")}`}
            >
              {inputValue === suggestion && (
                <Check className="mr-2 h-4 w-4 text-primary" />
              )}
              <span className={cn(inputValue !== suggestion && "ml-6")}>
                {suggestion}
              </span>
            </li>
          ))}
        </ul>
      )}
    </div>
  );
}