"use client";

import { useRef, useEffect, useCallback } from "react";
import { useRouter, usePathname } from "next/navigation";
import { motion } from "framer-motion";
import { Search, CornerDownLeft } 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=...
 *
 * State is controlled by the parent (PageHeader) so the header can
 * hide/show adjacent elements (logo, reading settings) on mobile.
 *
 * Pressing Escape or clicking outside collapses the input.
 * Keyboard shortcut: "/" focuses the search from anywhere on the page.
 */
/** Map the current pathname to the search `type` filter value. */
function searchTypeFromPath(pathname: string): string | null {
  if (pathname.startsWith("/books")) return "books";
  if (pathname.startsWith("/letters")) return "letters";
  if (pathname.startsWith("/essays")) return "essays";
  if (pathname.startsWith("/transcriptions")) return "transcriptions";
  if (pathname.startsWith("/glossary")) return "glossary";
  if (pathname.startsWith("/journals")) return "journals";
  if (pathname.startsWith("/magazines")) return "magazines";
  if (pathname.startsWith("/other-documents")) return "other_documents";
  return null; // homepage, search page, about, etc. → "all"
}

export function HeaderSearchButton({
  expanded,
  onExpandedChange,
}: {
  expanded: boolean;
  onExpandedChange: (expanded: boolean) => void;
}) {
  const queryRef = useRef("");
  const inputRef = useRef<HTMLInputElement>(null);
  const containerRef = useRef<HTMLDivElement>(null);
  const router = useRouter();
  const pathname = usePathname();

  // Focus input when expanded
  useEffect(() => {
    if (expanded && inputRef.current) {
      const timer = setTimeout(() => inputRef.current?.focus(), 80);
      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)
      ) {
        onExpandedChange(false);
      }
    }

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

  // Global "/" shortcut to open search
  useEffect(() => {
    function handleKeyDown(e: KeyboardEvent) {
      const target = e.target as HTMLElement;
      if (
        target.tagName === "INPUT" ||
        target.tagName === "TEXTAREA" ||
        target.tagName === "SELECT" ||
        target.isContentEditable
      ) {
        return;
      }

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

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

  const handleSubmit = useCallback(() => {
    const trimmed = queryRef.current.trim();
    const params = new URLSearchParams();
    if (trimmed) params.set("q", trimmed);

    // Pre-select the search filter matching the current section
    const type = searchTypeFromPath(pathname);
    if (type) params.set("type", type);

    const qs = params.toString();
    router.push(`/search${qs ? `?${qs}` : ""}`);
    onExpandedChange(false);
    queryRef.current = "";
    if (inputRef.current) inputRef.current.value = "";
  }, [router, onExpandedChange, pathname]);

  const handleKeyDown = useCallback(
    (e: React.KeyboardEvent) => {
      if (e.key === "Enter") {
        e.preventDefault();
        handleSubmit();
      } else if (e.key === "Escape") {
        e.preventDefault();
        onExpandedChange(false);
        queryRef.current = "";
        if (inputRef.current) inputRef.current.value = "";
      }
    },
    [handleSubmit, onExpandedChange],
  );

  return (
    <div
      ref={containerRef}
      className={cn(
        "relative flex items-center",
        expanded && "max-md:flex-1 max-md:min-w-0",
      )}
    >
      {expanded ? (
        <motion.div
          key="search-input"
          initial={{ width: 36, opacity: 0 }}
          animate={{ width: "100%", opacity: 1 }}
          transition={{
            width: { type: "spring", stiffness: 400, damping: 30 },
            opacity: { duration: 0.15 },
          }}
          className={cn(
            "flex items-center gap-2 h-12 md:h-10 rounded-lg border border-border bg-background px-3 overflow-hidden",
            "max-md:w-full",
            "md:w-100!",
          )}
        >
          <input
            ref={inputRef}
            type="text"
            defaultValue=""
            onChange={(e) => {
              queryRef.current = e.target.value;
            }}
            onKeyDown={handleKeyDown}
            placeholder="Search..."
            className="flex-1 bg-transparent text-md md:text-sm text-foreground placeholder:text-muted-foreground outline-none min-w-0"
          />
          <button
            type="button"
            onClick={handleSubmit}
            className="shrink-0 inline-flex items-center gap-1.5 rounded-md bg-primary px-3 py-1.5 text-xs font-medium text-primary-foreground hover:bg-primary/90 transition-colors"
          >
            Search
            <CornerDownLeft className="size-3 opacity-70" />
          </button>
        </motion.div>
      ) : (
        <motion.button
          key="search-icon"
          initial={{ opacity: 0, scale: 0.85 }}
          animate={{ opacity: 1, scale: 1 }}
          transition={{ duration: 0.12 }}
          type="button"
          onClick={() => onExpandedChange(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-4.5" />
        </motion.button>
      )}
    </div>
  );
}