import { useState } from "react";
import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
import {
  ArrowDown,
  ArrowUp,
  Eye,
  EyeOff,
  History,
  Plus,
  RefreshCw,
  Search,
  UserMinus,
  X,
} from "lucide-react";
import { api, type ManagedChannel, type Tag } from "../lib/api";
import { formatEta } from "../lib/format";
import { notify } from "../lib/notifications";
import Tooltip from "./Tooltip";

export default function Channels({
  canWrite,
  onViewChannel,
}: {
  canWrite: boolean;
  onViewChannel: (id: string, name: string) => void;
}) {
  const qc = useQueryClient();
  const channelsQuery = useQuery({ queryKey: ["channels"], queryFn: api.channels });
  const tagsQuery = useQuery({ queryKey: ["tags"], queryFn: api.tags });
  const statusQuery = useQuery({ queryKey: ["my-status"], queryFn: api.myStatus });
  const [q, setQ] = useState("");
  const [newTag, setNewTag] = useState("");

  const invalidate = () => {
    qc.invalidateQueries({ queryKey: ["channels"] });
    qc.invalidateQueries({ queryKey: ["tags"] });
    qc.invalidateQueries({ queryKey: ["my-status"] });
  };

  const userTags = (tagsQuery.data ?? []).filter((t) => !t.system);

  const patch = useMutation({
    mutationFn: (v: {
      id: string;
      body: { priority?: number; hidden?: boolean; deep_requested?: boolean };
    }) => api.updateChannel(v.id, v.body),
    // Requesting full history may have just pulled in a channel's recent uploads, so
    // refresh the per-user status and feed too — not only the channel list.
    onSuccess: () => {
      qc.invalidateQueries({ queryKey: ["channels"] });
      qc.invalidateQueries({ queryKey: ["my-status"] });
      qc.invalidateQueries({ queryKey: ["feed"] });
      qc.invalidateQueries({ queryKey: ["feed-count"] });
    },
  });
  const attach = useMutation({
    mutationFn: (v: { id: string; tagId: number }) => api.attachChannelTag(v.id, v.tagId),
    onSuccess: () => qc.invalidateQueries({ queryKey: ["channels"] }),
  });
  const detach = useMutation({
    mutationFn: (v: { id: string; tagId: number }) => api.detachChannelTag(v.id, v.tagId),
    onSuccess: () => qc.invalidateQueries({ queryKey: ["channels"] }),
  });
  const syncSubs = useMutation({
    mutationFn: () => api.syncSubscriptions(),
    onSuccess: (r: { subscriptions?: number }) => {
      invalidate();
      notify({ level: "success", message: `Synced ${r.subscriptions ?? 0} subscriptions` });
    },
    onError: () => notify({ level: "error", message: "Subscription sync failed" }),
  });
  const createTag = useMutation({
    mutationFn: (name: string) => api.createTag({ name, category: "other" }),
    onSuccess: () => {
      setNewTag("");
      qc.invalidateQueries({ queryKey: ["tags"] });
    },
  });
  const deleteTag = useMutation({
    mutationFn: (id: number) => api.deleteTag(id),
    onSuccess: () => invalidate(),
  });
  const unsubscribe = useMutation({
    mutationFn: (id: string) => api.unsubscribeChannel(id),
    onSuccess: () => {
      qc.invalidateQueries({ queryKey: ["channels"] });
      qc.invalidateQueries({ queryKey: ["my-status"] });
      notify({ level: "success", message: "Unsubscribed on YouTube" });
    },
    onError: () => notify({ level: "error", message: "Unsubscribe failed" }),
  });
  const deepAll = useMutation({
    mutationFn: () => api.deepAll(true),
    onSuccess: (r: { updated?: number }) => {
      qc.invalidateQueries({ queryKey: ["channels"] });
      qc.invalidateQueries({ queryKey: ["my-status"] });
      notify({
        level: "success",
        message: `Full history requested for ${r.updated ?? 0} channels`,
      });
    },
    onError: () => notify({ level: "error", message: "Couldn't request full history" }),
  });

  const channels = (channelsQuery.data ?? []).filter(
    (c) => !q || (c.title ?? "").toLowerCase().includes(q.toLowerCase())
  );
  const s = statusQuery.data;

  return (
    <div className="p-4 max-w-4xl mx-auto">
      {/* Per-user sync status */}
      {s && (
        <div className="flex flex-wrap items-center gap-x-5 gap-y-1 text-sm text-muted mb-4">
          <Stat label="Channels" value={s.channels_total} hint="Channels you're subscribed to." />
          <Stat
            label="Recent synced"
            value={`${s.channels_recent_synced}/${s.channels_total}`}
            hint="Channels whose recent uploads are in the local DB and show in your feed."
          />
          <Stat
            label="Full history"
            value={`${s.channels_deep_done}/${s.channels_deep_requested}`}
            hint="Channels whose entire back-catalog is fetched, out of the ones you've requested full history for."
          />
          {s.deep_pending_count > 0 && (
            <Stat
              label="left"
              value={formatEta(s.deep_eta_seconds)}
              hint={`Rough estimate to finish full-history backfill of ${s.deep_pending_count} pending channel(s), based on the shared daily quota.`}
            />
          )}
          <Stat label="My videos" value={s.my_videos.toLocaleString()} hint="Total videos available across your channels." />
          <Stat
            label="Quota left"
            value={s.quota_remaining_today.toLocaleString()}
            hint="Shared YouTube API budget left today (resets midnight US Pacific)."
          />
        </div>
      )}

      {/* Toolbar */}
      <div className="flex items-center gap-2 mb-4">
        <div className="relative flex-1">
          <Search className="w-4 h-4 absolute left-3 top-1/2 -translate-y-1/2 text-muted" />
          <input
            value={q}
            onChange={(e) => setQ(e.target.value)}
            placeholder="Filter channels…"
            className="w-full bg-card border border-border rounded-full pl-9 pr-4 py-2 text-sm outline-none focus:border-accent"
          />
        </div>
        <Tooltip
          side="bottom"
          hint="Re-import your subscription list from YouTube — adds channels you've newly followed and drops ones you've unfollowed. The videos themselves keep syncing automatically in the background; this does not re-fetch them."
        >
          <button
            onClick={() => syncSubs.mutate()}
            disabled={syncSubs.isPending}
            className="glass-card glass-hover flex items-center gap-2 px-3 py-2 rounded-xl text-sm disabled:opacity-50 transition"
          >
            <RefreshCw className={`w-4 h-4 ${syncSubs.isPending ? "animate-spin" : ""}`} />
            Sync subscriptions
          </button>
        </Tooltip>
        <Tooltip
          side="bottom"
          hint="Request full back-catalog backfill for every channel you're subscribed to. Older videos and search become complete as the shared daily quota allows — this can take a while."
        >
          <button
            onClick={() => deepAll.mutate()}
            disabled={deepAll.isPending}
            className="glass-card glass-hover flex items-center gap-2 px-3 py-2 rounded-xl text-sm disabled:opacity-50 transition"
          >
            <History className={`w-4 h-4 ${deepAll.isPending ? "animate-pulse" : ""}`} />
            Backfill everything
          </button>
        </Tooltip>
      </div>

      <p className="text-xs text-muted mb-4 leading-relaxed">
        Set a channel's <b className="text-fg/80">priority</b> to push its videos up when you sort
        by “Channel priority”, attach your own <b className="text-fg/80">tags</b> to filter the feed,
        or <b className="text-fg/80">hide</b> a channel to drop it from the feed without unsubscribing.
      </p>

      {/* Your tags */}
      <div className="flex flex-wrap items-center gap-1.5 mb-4">
        <Tooltip hint="Your personal labels. Attach them to channels below, then filter the feed by tag from the sidebar. (Separate from the automatic language/topic tags.)">
          <span className="text-xs uppercase tracking-wide text-muted mr-1 cursor-help underline decoration-dotted decoration-muted/40 underline-offset-4">
            Your tags
          </span>
        </Tooltip>
        {userTags.map((t) => (
          <span
            key={t.id}
            className="inline-flex items-center gap-1 text-xs px-2 py-1 rounded-full bg-card border border-border"
          >
            {t.name}
            <button onClick={() => deleteTag.mutate(t.id)} className="text-muted hover:text-red-400">
              <X className="w-3 h-3" />
            </button>
          </span>
        ))}
        <form
          onSubmit={(e) => {
            e.preventDefault();
            if (newTag.trim()) createTag.mutate(newTag.trim());
          }}
          className="inline-flex items-center gap-1"
        >
          <input
            value={newTag}
            onChange={(e) => setNewTag(e.target.value)}
            placeholder="new tag"
            className="w-24 bg-card border border-border rounded-full px-2.5 py-1 text-xs outline-none focus:border-accent"
          />
          <button type="submit" className="text-muted hover:text-accent" title="Create tag">
            <Plus className="w-4 h-4" />
          </button>
        </form>
      </div>

      {/* Channel list */}
      {channelsQuery.isLoading ? (
        <div className="text-muted py-8">Loading channels…</div>
      ) : channels.length === 0 ? (
        <div className="text-muted py-8">No channels.</div>
      ) : (
        <div className="flex flex-col gap-1.5">
          {channels.map((c) => (
            <ChannelRow
              key={c.id}
              c={c}
              userTags={userTags}
              canWrite={canWrite}
              onUnsubscribe={() => {
                if (
                  window.confirm(
                    `Unsubscribe from "${c.title ?? c.id}" on YouTube? This changes your real YouTube account. To just remove it from your feed, hide it instead.`
                  )
                )
                  unsubscribe.mutate(c.id);
              }}
              onView={() => onViewChannel(c.id, c.title ?? "This channel")}
              onPriority={(d) => patch.mutate({ id: c.id, body: { priority: c.priority + d } })}
              onHide={() => patch.mutate({ id: c.id, body: { hidden: !c.hidden } })}
              onDeep={() =>
                patch.mutate({ id: c.id, body: { deep_requested: !c.deep_requested } })
              }
              onToggleTag={(tagId) =>
                c.tag_ids.includes(tagId)
                  ? detach.mutate({ id: c.id, tagId })
                  : attach.mutate({ id: c.id, tagId })
              }
            />
          ))}
        </div>
      )}
    </div>
  );
}

function Stat({
  label,
  value,
  hint,
}: {
  label: string;
  value: string | number;
  hint?: string;
}) {
  return (
    <Tooltip hint={hint ?? ""}>
      <span className={hint ? "cursor-help" : ""}>
        <span className="text-fg font-semibold">{value}</span> {label}
      </span>
    </Tooltip>
  );
}

function SyncBadge({ ok, label, hint }: { ok: boolean; label: string; hint?: string }) {
  return (
    <Tooltip hint={hint ?? ""}>
      <span
        className={`text-[10px] px-1.5 py-0.5 rounded-full border ${
          ok ? "border-accent/40 text-accent" : "border-border text-muted"
        }`}
      >
        {label}
      </span>
    </Tooltip>
  );
}

function ChannelRow({
  c,
  userTags,
  canWrite,
  onUnsubscribe,
  onView,
  onPriority,
  onHide,
  onDeep,
  onToggleTag,
}: {
  c: ManagedChannel;
  userTags: Tag[];
  canWrite: boolean;
  onUnsubscribe: () => void;
  onView: () => void;
  onPriority: (delta: number) => void;
  onHide: () => void;
  onDeep: () => void;
  onToggleTag: (tagId: number) => void;
}) {
  return (
    <div
      className={`glass-card glass-hover flex items-center gap-3 p-2.5 rounded-xl transition ${
        c.hidden ? "opacity-60" : ""
      }`}
    >
      <Tooltip hint="Your ranking for this channel. Sort the feed by “Channel priority” to bring higher-priority channels to the top.">
        <div className="flex flex-col items-center cursor-help">
          <button onClick={() => onPriority(1)} className="text-muted hover:text-accent" aria-label="Raise priority">
            <ArrowUp className="w-3.5 h-3.5" />
          </button>
          <span className="text-xs text-muted tabular-nums">{c.priority}</span>
          <button onClick={() => onPriority(-1)} className="text-muted hover:text-accent" aria-label="Lower priority">
            <ArrowDown className="w-3.5 h-3.5" />
          </button>
        </div>
      </Tooltip>

      {c.thumbnail_url ? (
        <img src={c.thumbnail_url} alt="" className="w-10 h-10 rounded-full shrink-0" />
      ) : (
        <div className="w-10 h-10 rounded-full bg-card shrink-0" />
      )}

      <div className="min-w-0 flex-1">
        <button onClick={onView} className="text-sm font-semibold truncate hover:text-accent block max-w-full text-left">
          {c.title ?? c.id}
        </button>
        <div className="flex items-center gap-2 text-[11px] text-muted">
          <span>{c.stored_videos.toLocaleString()} stored</span>
          {c.subscriber_count != null && <span>· {c.subscriber_count.toLocaleString()} subs</span>}
        </div>
        <div className="flex flex-wrap items-center gap-1 mt-1">
          <SyncBadge
            ok={c.recent_synced}
            label="recent"
            hint={c.recent_synced ? "Recent uploads synced." : "Recent uploads not fetched yet."}
          />
          {c.backfill_done ? (
            <SyncBadge ok label="full" hint="Full history fetched." />
          ) : (
            <Tooltip
              hint={
                c.deep_requested
                  ? "Full history requested — this channel's whole back-catalog will backfill as the shared quota allows. Click to cancel the request."
                  : "Only recent uploads so far. Click to request this channel's full back-catalog (older videos + complete search)."
              }
            >
              <button
                onClick={onDeep}
                className={`inline-flex items-center gap-1 text-[10px] px-1.5 py-0.5 rounded-full border transition ${
                  c.deep_requested
                    ? "bg-accent text-accent-fg border-accent"
                    : "bg-card border-border text-muted hover:border-accent"
                }`}
              >
                <History className="w-3 h-3" />
                {c.deep_requested ? "full history queued" : "get full history"}
              </button>
            </Tooltip>
          )}
          {userTags.map((t) => {
            const on = c.tag_ids.includes(t.id);
            return (
              <button
                key={t.id}
                onClick={() => onToggleTag(t.id)}
                className={`text-[10px] px-1.5 py-0.5 rounded-full border transition ${
                  on
                    ? "bg-accent text-accent-fg border-accent"
                    : "bg-card border-border text-muted hover:border-accent"
                }`}
              >
                {t.name}
              </button>
            );
          })}
        </div>
      </div>

      <Tooltip
        hint={
          c.hidden
            ? "Hidden — this channel's videos are kept out of your feed. Click to show them again."
            : "Hide this channel's videos from your feed. It stays subscribed; this doesn't unsubscribe on YouTube."
        }
      >
        <button onClick={onHide} className="text-muted hover:text-fg shrink-0" aria-label={c.hidden ? "Unhide" : "Hide from feed"}>
          {c.hidden ? <EyeOff className="w-4 h-4" /> : <Eye className="w-4 h-4" />}
        </button>
      </Tooltip>

      {canWrite && (
        <Tooltip hint="Unsubscribe from this channel on YouTube (changes your real account). Read-only mode hides this — use Hide instead.">
          <button
            onClick={onUnsubscribe}
            className="text-muted hover:text-red-400 shrink-0"
            aria-label="Unsubscribe on YouTube"
          >
            <UserMinus className="w-4 h-4" />
          </button>
        </Tooltip>
      )}
    </div>
  );
}