"use client";

import { useState, useRef, useEffect, useCallback } from "react";
import { useRouter } from "next/navigation";
import { motion, AnimatePresence } from "framer-motion";
import { Search, X } from "lucide-react";
import { cn } from "@/lib/utils";

/**
 * HeaderSearchButton — a search icon in the page header that expands
 * into a full search input on click. Typing a query and pressing Enter
 * (or clicking the search icon again) navigates to /search?q=...
 *
 * The expansion/collapse is animated with framer-motion.
 * Pressing Escape or clicking outside collapses the input.
 * Keyboard shortcut: "/" focuses the search from anywhere on the page.
 */
export function HeaderSearchButton() {
  const [expanded, setExpanded] = useState(false);
  const [query, setQuery] = useState("");
  const inputRef = useRef<HTMLInputElement>(null);
  const containerRef = useRef<HTMLDivElement>(null);
  const router = useRouter();

  // Focus input when expanded
  useEffect(() => {
    if (expanded && inputRef.current) {
      // Small delay to let the animation start before focusing
      const timer = setTimeout(() => inputRef.current?.focus(), 50);
      return () => clearTimeout(timer);
    }
  }, [expanded]);

  // Close on outside click
  useEffect(() => {
    if (!expanded) return;

    function handleClick(e: MouseEvent) {
      if (
        containerRef.current &&
        !containerRef.current.contains(e.target as Node)
      ) {
        setExpanded(false);
      }
    }

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

  // Global "/" shortcut to open search
  useEffect(() => {
    function handleKeyDown(e: KeyboardEvent) {
      // Don't trigger if user is typing in an input/textarea
      const target = e.target as HTMLElement;
      if (
        target.tagName === "INPUT" ||
        target.tagName === "TEXTAREA" ||
        target.tagName === "SELECT" ||
        target.isContentEditable
      ) {
        return;
      }

      if (e.key === "/") {
        e.preventDefault();
        setExpanded(true);
      }
    }

    document.addEventListener("keydown", handleKeyDown);
    return () => document.removeEventListener("keydown", handleKeyDown);
  }, []);

  const handleSubmit = useCallback(() => {
    const trimmed = query.trim();
    if (trimmed) {
      router.push(`/search?q=${encodeURIComponent(trimmed)}`);
      setExpanded(false);
      setQuery("");
    } else {
      router.push("/search");
      setExpanded(false);
    }
  }, [query, router]);

  const handleKeyDown = useCallback(
    (e: React.KeyboardEvent) => {
      if (e.key === "Enter") {
        e.preventDefault();
        handleSubmit();
      } else if (e.key === "Escape") {
        e.preventDefault();
        setExpanded(false);
        setQuery("");
      }
    },
    [handleSubmit],
  );

  return (
    <div ref={containerRef} className="relative flex items-center">
      <AnimatePresence mode="wait">
        {expanded ? (
          <motion.div
            key="search-input"
            initial={{ width: 36, opacity: 0.8 }}
            animate={{ width: 280, opacity: 1 }}
            exit={{ width: 36, opacity: 0.8 }}
            transition={{ type: "spring", damping: 25, stiffness: 350 }}
            className="flex items-center gap-2 h-9 rounded-lg border border-border bg-background px-3 overflow-hidden"
          >
            <button
              type="button"
              onClick={handleSubmit}
              aria-label="Search"
              className="shrink-0 text-muted-foreground hover:text-foreground transition-colors"
            >
              <Search className="size-4" />
            </button>
            <input
              ref={inputRef}
              type="text"
              value={query}
              onChange={(e) => setQuery(e.target.value)}
              onKeyDown={handleKeyDown}
              placeholder="Search..."
              className="flex-1 bg-transparent text-sm text-foreground placeholder:text-muted-foreground outline-none min-w-0"
            />
            <button
              type="button"
              onClick={() => {
                setExpanded(false);
                setQuery("");
              }}
              aria-label="Close search"
              className="shrink-0 text-muted-foreground hover:text-foreground transition-colors"
            >
              <X className="size-3.5" />
            </button>
          </motion.div>
        ) : (
          <motion.button
            key="search-icon"
            initial={{ opacity: 0.8, scale: 0.9 }}
            animate={{ opacity: 1, scale: 1 }}
            exit={{ opacity: 0.8, scale: 0.9 }}
            transition={{ duration: 0.15 }}
            type="button"
            onClick={() => setExpanded(true)}
            aria-label="Search (press /)"
            title="Search (press /)"
            className={cn(
              "size-9 inline-flex items-center justify-center rounded-lg",
              "text-muted-foreground hover:text-foreground hover:bg-muted",
              "transition-colors outline-none",
              "focus-visible:ring-2 focus-visible:ring-ring",
            )}
          >
            <Search className="size-[18px]" />
          </motion.button>
        )}
      </AnimatePresence>
    </div>
  );
}