import { useMutation, useQueryClient } from "@tanstack/react-query";
import { ExternalLink, ImagePlus, Trash2, X } from "lucide-react";
import {
  useRef,
  useState,
  type ChangeEvent,
  type DragEvent,
} from "react";
import { Link } from "react-router-dom";

import { Button, Spinner } from "@/components/ui";
import { api, errorMessage, uploadFile } from "@/lib/api";
import { cn } from "@/lib/cn";
import {
  e621ErrorMessage,
  effectiveCredentials,
  iqdbSearch,
  RATING_LABELS,
  type E621IqdbResult,
} from "@/lib/e621";
import { formatBytes, formatDate } from "@/lib/format";
import type { SimilarityCheck } from "@/lib/types";
import { useE621 } from "@/store/e621";
import { toast } from "@/store/toasts";

const VIDEO_RE = /\.(mp4|webm)$/i;

const ratingPill: Record<string, string> = {
  s: "bg-ctp-green text-ctp-crust",
  q: "bg-ctp-peach text-ctp-crust",
  e: "bg-ctp-red text-ctp-crust",
};

export default function SimilarPage() {
  const queryClient = useQueryClient();
  const credentials = useE621((state) => state.credentials);
  const inputRef = useRef<HTMLInputElement>(null);

  const [file, setFile] = useState<File | null>(null);
  const [check, setCheck] = useState<SimilarityCheck | null>(null);
  const [uploading, setUploading] = useState(false);
  const [percent, setPercent] = useState(0);
  const [dragging, setDragging] = useState(false);

  const [iqdb, setIqdb] = useState<E621IqdbResult[] | null>(null);
  const [iqdbBusy, setIqdbBusy] = useState(false);
  const [selected, setSelected] = useState<E621IqdbResult | null>(null);

  const configured = Boolean(credentials?.configured);

  const deleteMutation = useMutation({
    mutationFn: () =>
      api(`/api/similarity/${check?.check_id}/`, { method: "DELETE" }),
    onSuccess: () => {
      setCheck(null);
      setFile(null);
      setIqdb(null);
      setSelected(null);
      if (inputRef.current) inputRef.current.value = "";
      toast.ok("Temporary copy deleted.");
    },
    onError: (error) => toast.error(errorMessage(error)),
  });

  async function startCheck(selectedFile: File) {
    setFile(selectedFile);
    setCheck(null);
    setIqdb(null);
    setSelected(null);
    setPercent(0);
    setUploading(true);
    try {
      const data = await uploadFile<SimilarityCheck>(
        selectedFile,
        {},
        setPercent,
        "/api/similarity/",
      );
      setCheck(data);
      void queryClient.invalidateQueries({ queryKey: ["files"] });
    } catch (err) {
      toast.error(errorMessage(err));
    } finally {
      setUploading(false);
    }

    if (VIDEO_RE.test(selectedFile.name)) return;
    if (!configured) return;
    setIqdbBusy(true);
    try {
      const results = await iqdbSearch(
        effectiveCredentials(credentials),
        selectedFile,
        selectedFile.name,
      );
      setIqdb(results);
    } catch (err) {
      toast.error(e621ErrorMessage(err));
    } finally {
      setIqdbBusy(false);
    }
  }

  function handleInput(event: ChangeEvent<HTMLInputElement>) {
    const chosen = event.target.files?.[0];
    if (chosen) void startCheck(chosen);
  }

  function handleDrop(event: DragEvent<HTMLDivElement>) {
    event.preventDefault();
    setDragging(false);
    const dropped = event.dataTransfer.files?.[0];
    if (dropped) void startCheck(dropped);
  }

  const isVideo = file ? VIDEO_RE.test(file.name) : false;
  const exact = check?.results.exact ?? null;
  const matches = check?.results.matches ?? [];

  return (
    <div className="mx-auto flex w-full max-w-6xl flex-col gap-6">
      <header>
        <h1 className="text-lg font-semibold">Similarity check</h1>
        <p className="mt-1 text-sm text-ctp-overlay0">
          Drop a file to see whether it is already in the library and what it
          looks like on e621. Nothing is added to the library — the temporary
          copy is deleted automatically after a while and on the next server
          start.
        </p>
      </header>

      <div
        onDragOver={(event) => {
          event.preventDefault();
          setDragging(true);
        }}
        onDragLeave={() => setDragging(false)}
        onDrop={handleDrop}
        className={cn(
          "flex flex-col items-center justify-center gap-2 rounded-lg border border-dashed px-6 py-10 text-center transition",
          dragging
            ? "border-ctp-mauve bg-ctp-mauve/10"
            : "border-ctp-surface1 bg-ctp-base",
        )}
      >
        <ImagePlus className="h-6 w-6 text-ctp-overlay0" />
        <p className="text-sm text-ctp-subtext0">
          Drag a file here, or{" "}
          <button
            type="button"
            className="text-ctp-blue hover:underline"
            onClick={() => inputRef.current?.click()}
          >
            choose one
          </button>
        </p>
        <p className="text-[11px] text-ctp-overlay0">
          Images get the full check (MD5, visual hashes, e621 IQDB); videos
          only get the exact MD5 match.
        </p>
        <input
          ref={inputRef}
          type="file"
          className="hidden"
          onChange={handleInput}
        />
      </div>

      {uploading ? (
        <div className="flex items-center gap-3">
          <div className="h-1.5 w-48 overflow-hidden rounded-full bg-ctp-surface0">
            <div
              className="h-full bg-ctp-mauve transition-all"
              style={{ width: `${percent}%` }}
            />
          </div>
          <span className="font-mono text-xs text-ctp-overlay0">
            uploading… {percent}%
          </span>
        </div>
      ) : null}

      {check ? (
        <div className="grid gap-6 lg:grid-cols-[320px_minmax(0,1fr)]">
          <aside className="flex flex-col gap-4">
            <section className="overflow-hidden rounded-lg border border-ctp-surface0 bg-ctp-base">
              <div className="flex max-h-72 items-center justify-center overflow-hidden bg-ctp-mantle">
                {check.file_url ? (
                  isVideo ? (
                    <video
                      src={check.file_url}
                      controls
                      loop
                      muted
                      className="max-h-72 w-full object-contain"
                    />
                  ) : (
                    <img
                      src={check.file_url}
                      alt={check.original_filename}
                      className="max-h-72 w-full object-contain"
                    />
                  )
                ) : null}
              </div>
              <div className="p-3">
                <p
                  className="truncate font-mono text-xs text-ctp-subtext1"
                  title={check.original_filename}
                >
                  {check.original_filename}
                </p>
                <p className="mt-1 truncate font-mono text-[10px] text-ctp-overlay0">
                  {check.md5}
                </p>
                <p className="mt-1 text-[11px] text-ctp-overlay0">
                  {formatBytes(check.size)} · expires{" "}
                  {formatDate(check.expires_at)}
                </p>
                <div className="mt-3 flex items-center gap-2">
                  <Button
                    variant="danger"
                    className="px-2 py-1 text-xs"
                    disabled={deleteMutation.isPending}
                    onClick={() => deleteMutation.mutate()}
                  >
                    <Trash2 className="h-3.5 w-3.5" /> Delete now
                  </Button>
                  <Button
                    variant="ghost"
                    className="px-2 py-1 text-xs"
                    onClick={() => {
                      setCheck(null);
                      setFile(null);
                      setIqdb(null);
                      setSelected(null);
                      if (inputRef.current) inputRef.current.value = "";
                    }}
                  >
                    <X className="h-3.5 w-3.5" /> Clear
                  </Button>
                </div>
              </div>
            </section>
          </aside>

          <div className="flex min-w-0 flex-col gap-6">
            <section className="rounded-lg border border-ctp-surface0 bg-ctp-base p-4">
              <h2 className="text-sm font-semibold text-ctp-subtext1">
                In the library (exact MD5)
              </h2>
              {exact ? (
                <Link
                  to={`/detail/${exact.j_id}`}
                  className="mt-3 flex items-center gap-3 rounded-md border border-ctp-green/40 bg-ctp-green/10 p-2 transition hover:bg-ctp-green/15"
                >
                  {exact.thumbnail_url ? (
                    <img
                      src={exact.thumbnail_url}
                      alt={exact.j_id}
                      className="h-14 w-14 rounded object-cover"
                    />
                  ) : null}
                  <span className="min-w-0">
                    <span className="block font-mono text-sm text-ctp-text">
                      {exact.j_id}
                    </span>
                    <span className="block truncate text-xs text-ctp-overlay0">
                      {exact.filename} · {formatBytes(exact.size)} ·{" "}
                      {exact.location_count} cop
                      {exact.location_count === 1 ? "y" : "ies"}
                      {exact.e621_post_id
                        ? ` · e621 #${exact.e621_post_id}`
                        : ""}
                    </span>
                  </span>
                </Link>
              ) : (
                <p className="mt-3 text-xs text-ctp-overlay0">
                  Not in the library — no item has this MD5.
                </p>
              )}
            </section>

            <section className="rounded-lg border border-ctp-surface0 bg-ctp-base p-4">
              <h2 className="text-sm font-semibold text-ctp-subtext1">
                Visually similar in the library{" "}
                <span className="font-mono text-[11px] text-ctp-overlay0">
                  {matches.length}
                </span>
              </h2>
              {isVideo ? (
                <p className="mt-3 text-xs text-ctp-overlay0">
                  Visual hashing works on images only.
                </p>
              ) : matches.length === 0 ? (
                <p className="mt-3 text-xs text-ctp-overlay0">
                  Nothing above the similarity threshold.
                </p>
              ) : (
                <div className="mt-3 grid grid-cols-2 gap-3 sm:grid-cols-3 xl:grid-cols-4">
                  {matches.map((match) => (
                    <Link
                      key={match.j_id}
                      to={`/detail/${match.j_id}`}
                      className="group overflow-hidden rounded-lg border border-ctp-surface0 bg-ctp-base transition hover:border-ctp-surface2"
                    >
                      <span className="relative block aspect-square overflow-hidden bg-ctp-mantle">
                        {match.thumbnail_url ? (
                          <img
                            src={match.thumbnail_url}
                            alt={match.j_id}
                            loading="lazy"
                            className="h-full w-full object-cover transition group-hover:scale-[1.03]"
                          />
                        ) : null}
                        <span className="absolute right-2 top-2 rounded-sm bg-ctp-crust/80 px-1.5 py-0.5 font-mono text-[10px] text-ctp-subtext0">
                          {match.similarity}%
                        </span>
                      </span>
                      <span className="block px-2 py-1.5 font-mono text-[11px] text-ctp-subtext0">
                        {match.j_id}
                      </span>
                    </Link>
                  ))}
                </div>
              )}
            </section>

            <section className="rounded-lg border border-ctp-surface0 bg-ctp-base p-4">
              <div className="flex items-center justify-between gap-2">
                <h2 className="text-sm font-semibold text-ctp-subtext1">
                  e621 IQDB
                </h2>
                {iqdbBusy ? (
                  <span className="flex items-center gap-1.5 text-[11px] text-ctp-overlay0">
                    <Spinner className="h-3 w-3" /> searching…
                  </span>
                ) : iqdb ? (
                  <span className="font-mono text-[11px] text-ctp-overlay0">
                    {iqdb.length} candidate(s)
                  </span>
                ) : null}
              </div>

              {isVideo ? (
                <p className="mt-3 text-xs text-ctp-overlay0">
                  IQDB works on images only.
                </p>
              ) : !configured ? (
                <p className="mt-3 text-xs text-ctp-overlay0">
                  <Link to="/account" className="text-ctp-blue hover:underline">
                    Add e621 credentials
                  </Link>{" "}
                  to reverse-search this image on e621.
                </p>
              ) : iqdbBusy && !iqdb ? (
                <div className="mt-3 flex justify-center py-4">
                  <Spinner className="h-4 w-4" />
                </div>
              ) : iqdb && iqdb.length === 0 ? (
                <p className="mt-3 text-xs text-ctp-overlay0">
                  No similar posts found on e621.
                </p>
              ) : iqdb ? (
                <>
                  <div className="mt-3 grid grid-cols-3 gap-2 sm:grid-cols-4 xl:grid-cols-6">
                    {iqdb.map((candidate) => {
                      const isExact =
                        candidate.md5 !== null &&
                        check.md5 === candidate.md5;
                      return (
                        <button
                          key={`${candidate.post_id}-${candidate.md5}`}
                          type="button"
                          disabled={candidate.post_id === null}
                          onClick={() => setSelected(candidate)}
                          className={cn(
                            "overflow-hidden rounded-md border bg-ctp-mantle text-left transition",
                            selected?.post_id === candidate.post_id
                              ? "border-ctp-mauve ring-2 ring-ctp-mauve/40"
                              : "border-ctp-surface0 hover:border-ctp-surface2",
                          )}
                        >
                          <span className="relative block aspect-square overflow-hidden">
                            {candidate.preview_url ? (
                              <img
                                src={candidate.preview_url}
                                alt={`Post #${candidate.post_id}`}
                                loading="lazy"
                                className="h-full w-full object-cover"
                              />
                            ) : (
                              <span className="flex h-full w-full items-center justify-center text-[10px] text-ctp-overlay0">
                                No preview
                              </span>
                            )}
                            {candidate.rating ? (
                              <span
                                className={cn(
                                  "absolute left-1 top-1 rounded-full px-1 py-0.5 font-mono text-[9px] font-semibold uppercase",
                                  ratingPill[candidate.rating] ??
                                    "bg-ctp-surface1 text-ctp-text",
                                )}
                              >
                                {candidate.rating}
                              </span>
                            ) : null}
                            {isExact ? (
                              <span className="absolute right-1 top-1 rounded-full bg-ctp-green/90 px-1 py-0.5 font-mono text-[9px] font-semibold uppercase text-ctp-crust">
                                MD5
                              </span>
                            ) : null}
                          </span>
                          <span className="block px-1 py-0.5 font-mono text-[10px] text-ctp-overlay0">
                            #{candidate.post_id}
                            {candidate.score !== null
                              ? ` · ${Math.round(candidate.score)}%`
                              : ""}
                          </span>
                        </button>
                      );
                    })}
                  </div>

                  {selected ? (
                    <div className="mt-3 rounded-md border border-ctp-surface0 bg-ctp-surface0/40 p-3">
                      <p className="font-mono text-xs text-ctp-subtext1">
                        Post #{selected.post_id}
                      </p>
                      <p className="mt-1 text-xs text-ctp-overlay0">
                        {selected.rating
                          ? (RATING_LABELS[selected.rating] ??
                            selected.rating)
                          : "Unknown rating"}
                        {selected.score_total !== null
                          ? ` · ▲ ${selected.score_total}`
                          : ""}
                        {selected.fav_count !== null
                          ? ` · ${selected.fav_count} favs`
                          : ""}
                        {selected.width && selected.height
                          ? ` · ${selected.width}×${selected.height}`
                          : ""}
                      </p>
                      {selected.tags_preview.length > 0 ? (
                        <div className="mt-2 flex flex-wrap gap-1">
                          {selected.tags_preview.map((tag) => (
                            <span
                              key={tag}
                              className="rounded border border-ctp-surface1 px-1 py-0.5 font-mono text-[10px] text-ctp-subtext0"
                            >
                              {tag}
                            </span>
                          ))}
                        </div>
                      ) : null}
                      <div className="mt-3 flex items-center gap-3">
                        <Link
                          to={`/detail/${selected.post_id}`}
                          className="inline-flex items-center gap-1.5 text-xs text-ctp-blue hover:underline"
                        >
                          <ExternalLink className="h-3.5 w-3.5" /> View post
                        </Link>
                      </div>
                    </div>
                  ) : (
                    <p className="mt-2 text-[11px] text-ctp-overlay0">
                      Select a candidate for its rating, score, favorites and
                      tags.
                    </p>
                  )}
                </>
              ) : (
                <p className="mt-3 text-xs text-ctp-overlay0">
                  Waiting for the library check…
                </p>
              )}
            </section>
          </div>
        </div>
      ) : null}
    </div>
  );
}