"use client";

import { useRef, useEffect, useState, useCallback } from "react";
import { IconTrash, IconGripHorizontal } from "@tabler/icons-react";
import { Button } from "@kandev/ui/button";
import { cn } from "@/lib/utils";
import type { DiffComment } from "@/lib/diff/types";

type CommentViewPopoverProps = {
  comments: DiffComment[];
  position: { x: number; y: number };
  onDelete: (commentId: string) => void;
  onClose: () => void;
};

type DragState = { startX: number; startY: number; origLeft: number; origTop: number };

function computePopoverInitialPos(
  position: { x: number; y: number },
  width: number,
  height: number,
) {
  let left = position.x;
  let top = position.y;
  if (left + width > window.innerWidth - 16) left = Math.max(16, window.innerWidth - width - 16);
  if (top + height > window.innerHeight - 16) top = Math.max(16, position.y - height);
  return { left, top };
}

function useDraggablePos(position: { x: number; y: number }, width: number, height: number) {
  const [pos, setPos] = useState(() => computePopoverInitialPos(position, width, height));
  const dragRef = useRef<DragState | null>(null);

  const onDragStart = useCallback(
    (e: React.MouseEvent) => {
      e.preventDefault();
      dragRef.current = {
        startX: e.clientX,
        startY: e.clientY,
        origLeft: pos.left,
        origTop: pos.top,
      };
      const onMove = (ev: MouseEvent) => {
        if (!dragRef.current) return;
        const dx = ev.clientX - dragRef.current.startX;
        const dy = ev.clientY - dragRef.current.startY;
        setPos({ left: dragRef.current.origLeft + dx, top: dragRef.current.origTop + dy });
      };
      const onUp = () => {
        dragRef.current = null;
        document.removeEventListener("mousemove", onMove);
        document.removeEventListener("mouseup", onUp);
      };
      document.addEventListener("mousemove", onMove);
      document.addEventListener("mouseup", onUp);
    },
    [pos.left, pos.top],
  );

  return { pos, onDragStart };
}

function usePopoverClose(onClose: () => void, popoverRef: React.RefObject<HTMLDivElement | null>) {
  useEffect(() => {
    const handleClickOutside = (e: MouseEvent) => {
      if (popoverRef.current && !popoverRef.current.contains(e.target as Node)) onClose();
    };
    const timer = setTimeout(() => {
      document.addEventListener("mousedown", handleClickOutside);
    }, 100);
    return () => {
      clearTimeout(timer);
      document.removeEventListener("mousedown", handleClickOutside);
    };
  }, [onClose, popoverRef]);

  useEffect(() => {
    const handleKeyDown = (e: KeyboardEvent) => {
      if (e.key === "Escape") {
        e.stopPropagation();
        onClose();
      }
    };
    document.addEventListener("keydown", handleKeyDown, true);
    return () => document.removeEventListener("keydown", handleKeyDown, true);
  }, [onClose]);
}

function formatLineRange(start: number, end: number) {
  return start === end ? `L${start}` : `L${start}-${end}`;
}

function CommentItem({
  comment,
  onDelete,
}: {
  comment: DiffComment;
  onDelete: (id: string) => void;
}) {
  return (
    <div className="p-3">
      <div className="flex items-center justify-between mb-2">
        <span className="px-2 py-0.5 rounded-md bg-muted text-[10px] font-mono text-muted-foreground">
          {formatLineRange(comment.startLine, comment.endLine)}
        </span>
        <Button
          size="sm"
          variant="ghost"
          className="h-6 w-6 p-0 cursor-pointer text-muted-foreground hover:text-destructive"
          onClick={() => onDelete(comment.id)}
        >
          <IconTrash className="h-3.5 w-3.5" />
        </Button>
      </div>
      {comment.codeContent && (
        <pre className="mb-2 p-2 rounded-md bg-muted/50 text-[10px] text-muted-foreground font-mono max-h-[80px] overflow-auto whitespace-pre-wrap">
          {comment.codeContent}
        </pre>
      )}
      <p className="text-xs text-foreground leading-relaxed">{comment.text}</p>
    </div>
  );
}

export function CommentViewPopover({
  comments,
  position,
  onDelete,
  onClose,
}: CommentViewPopoverProps) {
  const popoverRef = useRef<HTMLDivElement>(null);
  const { pos, onDragStart } = useDraggablePos(position, 350, 200);
  usePopoverClose(onClose, popoverRef);

  return (
    <div
      ref={popoverRef}
      className={cn(
        "fixed z-50 w-[350px] max-h-[350px] overflow-auto rounded-xl border border-border/50 bg-popover/95 backdrop-blur-sm shadow-xl",
        "animate-in fade-in-0 zoom-in-95 duration-150",
      )}
      style={{ left: pos.left, top: pos.top }}
    >
      <div
        className="flex items-center justify-between px-3 pt-2 pb-1 cursor-grab active:cursor-grabbing select-none sticky top-0 bg-popover/95 backdrop-blur-sm z-10"
        onMouseDown={onDragStart}
      >
        <span className="text-xs text-muted-foreground">
          {comments.length} comment{comments.length !== 1 ? "s" : ""}
        </span>
        <IconGripHorizontal className="h-3.5 w-3.5 text-muted-foreground/40" />
      </div>
      <div className="divide-y divide-border/30">
        {comments.map((comment) => (
          <CommentItem key={comment.id} comment={comment} onDelete={onDelete} />
        ))}
      </div>
    </div>
  );
}