"use client";

import { openLink } from "@/lib/open-link";
import {
  memo,
  useState,
  useRef,
  useEffect,
  useCallback,
  type ComponentProps,
  type FC,
} from "react";
import { useMessage } from "@assistant-ui/react";
import { cn } from "@/lib/utils";
import { Badge, badgeVariants, type BadgeProps } from "./badge";
import {
  HoverCard,
  HoverCardTrigger,
  HoverCardContent,
} from "@/components/ui/hover-card";

// ── Helpers ──────────────────────────────────────────────────

const extractDomain = (url: string): string => {
  try {
    return new URL(url).hostname.replace(/^www\./, "");
  } catch {
    return url;
  }
};

const getDomainInitial = (url: string): string => {
  const domain = extractDomain(url);
  return domain.charAt(0).toUpperCase();
};

// ── Sub-components ───────────────────────────────────────────

function SourceIcon({
  url,
  className,
  size = 3,
  allowRemoteIcons = true,
  ...props
}: ComponentProps<"span"> & { url: string; size?: number; allowRemoteIcons?: boolean }) {
  const [hasError, setHasError] = useState(false);
  const domain = extractDomain(url);
  const SIZE_CLASSES: Record<number, string> = { 3: "size-3", 4: "size-4", 5: "size-5" };
  const sizeClass = SIZE_CLASSES[size] ?? "size-3";

  // When disabled, render the letter fallback instead of fetching a third-party favicon.
  if (hasError || !allowRemoteIcons) {
    return (
      <span
        data-slot="source-icon-fallback"
        className={cn(
          `flex ${sizeClass} shrink-0 items-center justify-center rounded-sm bg-muted font-medium text-ui-10`,
          className,
        )}
        {...props}
      >
        {getDomainInitial(url)}
      </span>
    );
  }

  return (
    <img
      data-slot="source-icon"
      src={`https://www.google.com/s2/favicons?domain=${domain}&sz=32`}
      alt=""
      className={cn(`${sizeClass} shrink-0 rounded-sm`, className)}
      onError={() => setHasError(true)}
      {...(props as ComponentProps<"img">)}
    />
  );
}

function SourceTitle({ className, ...props }: ComponentProps<"span">) {
  return (
    <span
      data-slot="source-title"
      className={cn("max-w-37.5 truncate", className)}
      {...props}
    />
  );
}

export type SourceProps = Omit<BadgeProps, "asChild"> &
  ComponentProps<"a"> & {
    asChild?: boolean;
  };

function Source({
  className,
  variant,
  size,
  asChild = false,
  href,
  onClick,
  ...props
}: SourceProps) {
  return (
    <Badge
      asChild
      variant={variant}
      size={size}
      className={cn(
        "rounded-full cursor-pointer outline-none hover:bg-chat-icon-bg-hover! hover:text-chat-icon-fg-hover! focus-visible:border-ring",
        className,
      )}
    >
      <a
        data-slot="source"
        href={href}
        rel="noopener noreferrer"
        onClick={(e) => {
          if (href && openLink(href)) {
            e.preventDefault();
          }
          onClick?.(e);
        }}
        {...(props as ComponentProps<"a">)}
      />
    </Badge>
  );
}

// ── Source badge with hover card ─────────────────────────────

export interface SourceData {
  /**
   * Stable per-citation key. Two Anthropic citations into different spans of
   * the same source share a `url`, so React keys on `id` to keep them distinct.
   */
  id: string;
  url: string;
  title: string;
  description?: string;
}

const SourceBadge: FC<{ source: SourceData; allowRemoteIcons?: boolean }> = ({
  source,
  allowRemoteIcons = true,
}) => {
  const domain = extractDomain(source.url);
  const displayTitle = source.title || domain;

  return (
    <HoverCard openDelay={0} closeDelay={0}>
      <HoverCardTrigger asChild>
        <span className="inline-block">
          <Source href={source.url}>
            <SourceIcon url={source.url} allowRemoteIcons={allowRemoteIcons} />
            <SourceTitle>{displayTitle}</SourceTitle>
          </Source>
        </span>
      </HoverCardTrigger>
      <HoverCardContent
        side="top"
        align="start"
        className="!bg-black !text-white !w-72 !p-3 !rounded-2xl !shadow-md !ring-0 !duration-0"
        style={{ animation: "none" }}
      >
        <div className="flex gap-2.5">
          <SourceIcon
            url={source.url}
            size={4}
            className="mt-0.5 shrink-0"
            allowRemoteIcons={allowRemoteIcons}
          />
          <div className="min-w-0 space-y-1">
            <p className="text-sm font-semibold leading-tight truncate">
              {source.title || domain}
            </p>
            <p className="text-xs text-white/60 truncate">{domain}</p>
            {source.description && (
              <p className="text-xs text-white/70 leading-relaxed line-clamp-3">
                {source.description}
              </p>
            )}
          </div>
        </div>
      </HoverCardContent>
    </HoverCard>
  );
};

// ── Grouped sources with 2-row collapse ─────────────────────

const SourcesGroup: FC<{ sources?: SourceData[]; allowRemoteIcons?: boolean }> = ({
  sources: suppliedSources,
  allowRemoteIcons = true,
}) => {
  const message = useMessage();
  const containerRef = useRef<HTMLDivElement>(null);
  const [visibleCount, setVisibleCount] = useState<number | null>(null);
  const [expanded, setExpanded] = useState(false);

  const messageSources: SourceData[] = [];
  if (!suppliedSources && message.content) {
    for (const part of message.content) {
      if (
        part.type === "source" &&
        "sourceType" in part &&
        part.sourceType === "url" &&
        "url" in part &&
        part.url
      ) {
        const url = part.url as string;
        const partId =
          typeof (part as { id?: unknown }).id === "string"
            ? ((part as { id: string }).id)
            : url;
        messageSources.push({
          id: partId,
          url,
          title: (part as { title?: string }).title || "",
          description: (part as { metadata?: { description?: string } })
            .metadata?.description,
        });
      }
    }
  }
  const sources = suppliedSources ?? messageSources;

  // Measure how many badges fit in 2 rows
  const measure = useCallback(() => {
    const container = containerRef.current;
    if (!container || sources.length === 0) return;

    const children = Array.from(container.children) as HTMLElement[];
    if (children.length === 0) return;

    const firstTop = children[0].offsetTop;
    let rowCount = 1;
    let prevTop = firstTop;
    let cutoff = children.length;

    for (let i = 1; i < children.length; i++) {
      const childTop = children[i].offsetTop;
      if (childTop > prevTop) {
        rowCount++;
        prevTop = childTop;
        if (rowCount > 2) {
          cutoff = i;
          break;
        }
      }
    }

    setVisibleCount(rowCount > 2 ? cutoff : null);
  }, [sources.length]);

  useEffect(() => {
    measure();
  }, [measure]);

  // Re-measure on resize
  useEffect(() => {
    const container = containerRef.current;
    if (!container) return;
    const observer = new ResizeObserver(measure);
    observer.observe(container);
    return () => observer.disconnect();
  }, [measure]);

  if (sources.length === 0) return null;

  const shouldCollapse = visibleCount !== null && visibleCount < sources.length;
  const displayedSources =
    expanded || !shouldCollapse ? sources : sources.slice(0, visibleCount);
  const hiddenCount = sources.length - (visibleCount ?? sources.length);

  return (
    <div className="relative mt-2 mb-3">
      {/* Hidden measurement container: renders all badges off-screen to read
          each child's offsetTop and decide how many fit in two rows. The
          absolute/h-0/overflow-hidden wrapper clips the pills so they don't add
          to scrollHeight (~30px per row) and create a phantom empty scroll area
          below the message. offsetTop reads correctly because the wrapper is
          positioned (absolute) and the flex-wrapped children measure against it. */}
      <div
        aria-hidden
        className="absolute pointer-events-none overflow-hidden h-0 w-full left-0 top-0"
      >
        <div
          ref={containerRef}
          className="flex w-full flex-wrap gap-1 invisible"
        >
          {sources.map((source) => (
            <span key={source.id} className="inline-block">
              <Source href={source.url}>
                <SourceIcon url={source.url} allowRemoteIcons={allowRemoteIcons} />
                <SourceTitle>{source.title || extractDomain(source.url)}</SourceTitle>
              </Source>
            </span>
          ))}
        </div>
      </div>

      {/* Visible container */}
      <div className="flex flex-wrap gap-1">
        {displayedSources.map((source) => (
          <SourceBadge key={source.id} source={source} allowRemoteIcons={allowRemoteIcons} />
        ))}
        {shouldCollapse && !expanded && (
          <button
            type="button"
            onClick={() => setExpanded(true)}
            className={cn(
              badgeVariants({ variant: "outline", size: "default" }),
              "rounded-full cursor-pointer text-muted-foreground hover:bg-chat-icon-bg-hover! hover:text-chat-icon-fg-hover!",
            )}
          >
            +{hiddenCount} more
          </button>
        )}
        {shouldCollapse && expanded && (
          <button
            type="button"
            onClick={() => setExpanded(false)}
            className={cn(
              badgeVariants({ variant: "outline", size: "default" }),
              "rounded-full cursor-pointer text-muted-foreground hover:bg-chat-icon-bg-hover! hover:text-chat-icon-fg-hover!",
            )}
          >
            Show less
          </button>
        )}
      </div>
    </div>
  );
};

// ── Individual source (renders null — SourcesGroup handles all) ──

const SourcesNoop: FC<Record<string, unknown>> = () => null;

// ── Exports ──────────────────────────────────────────────────

const Sources = memo(SourcesNoop) as unknown as FC<Record<string, unknown>> & {
  Root: typeof Source;
  Icon: typeof SourceIcon;
  Title: typeof SourceTitle;
  Group: typeof SourcesGroup;
};

Sources.displayName = "Sources";
Sources.Root = Source;
Sources.Icon = SourceIcon;
Sources.Title = SourceTitle;
Sources.Group = SourcesGroup;

export {
  Sources,
  SourcesGroup,
  Source,
  SourceIcon,
  SourceTitle,
  badgeVariants as sourceVariants,
};
