import { useEffect, useState } from "react";
import { useNavigate } from "react-router-dom";
import { useAuth } from "../App";
import { ArrowRight, ChevronRight, Plus } from "../components/icons";
import { SideRail } from "../components/SideRail";
import { Button, EmptyState, Field, InlineAlert } from "../components/ui";
import { ApiError, api } from "../lib/client";
import type { Workspace } from "../lib/types";

function roleLabel(role: string): string {
  return { owner: "所有者", admin: "管理员", member: "成员", guest: "访客" }[role] ?? role;
}

function greeting() {
  const h = new Date().getHours();
  if (h < 6) return "夜深了";
  if (h < 11) return "早上好";
  if (h < 14) return "中午好";
  if (h < 18) return "下午好";
  return "晚上好";
}

/**
 * 首页 = 工作区总览。
 *
 * 壳和工作区里完全一样（同样的侧栏、同样的通栏内容区），
 * 这样"点进工作区"只是换内容，宽度和导航位置都不跳。
 */
export function HomePage() {
  const { user, workspaces, loading, reload } = useAuth();
  const navigate = useNavigate();
  const [name, setName] = useState("");
  const [creating, setCreating] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [busy, setBusy] = useState(false);

  useEffect(() => {
    if (!loading && !user) navigate("/login", { replace: true });
  }, [loading, user, navigate]);

  async function createWorkspace(event: React.FormEvent) {
    event.preventDefault();
    if (!name.trim()) return;
    setBusy(true);
    setError(null);
    try {
      const ws = await api.post<Workspace>("/workspaces", { name: name.trim() });
      setName("");
      setCreating(false);
      await reload();
      navigate(`/w/${ws.id}`);
    } catch (err) {
      setError(err instanceof ApiError ? err.message : "创建失败");
    } finally {
      setBusy(false);
    }
  }

  return (
    <div className="flex min-h-full flex-col bg-paper-100 lg:flex-row">
      <SideRail />

      <main className="min-w-0 flex-1">
        <div className="w-full px-5 py-6 lg:px-8 lg:py-8 xl:px-12 2xl:px-16">
          <div className="mb-7">
            <p className="text-xs font-medium tracking-wide text-clay-600">
              {new Date().toLocaleDateString("zh-CN", {
                month: "long",
                day: "numeric",
                weekday: "long",
              })}
            </p>
            <h1 className="mt-1.5 font-display text-3xl font-semibold">
              {greeting()}，{user?.nickname ?? ""}
            </h1>
            <p className="mt-2 max-w-2xl text-sm leading-relaxed text-ink-500">
              选一个工作区继续。任务、工单、知识都在里面，他们是同一件事的三个阶段。
            </p>
          </div>

          <div className="mb-3 flex items-center justify-between">
            <h2 className="text-sm font-medium text-ink-600">我的工作区</h2>
            <div className="flex items-center gap-3">
              <span className="text-2xs text-ink-400">{workspaces.length} 个</span>
              {!creating ? (
                <Button variant="ghost" size="sm" onClick={() => setCreating(true)}>
                  <Plus size={14} />
                  新建
                </Button>
              ) : null}
            </div>
          </div>

          {loading ? (
            <div className="grid gap-3 sm:grid-cols-2 xl:grid-cols-3 2xl:grid-cols-4">
              {[0, 1, 2].map((i) => (
                <div key={i} className="card h-[92px] animate-pulse bg-paper-50" />
              ))}
            </div>
          ) : (
            <div className="grid gap-3 sm:grid-cols-2 xl:grid-cols-3 2xl:grid-cols-4">
              {workspaces.map((ws) => (
                <button
                  key={ws.id}
                  onClick={() => navigate(`/w/${ws.id}`)}
                  className="group card flex items-center gap-3 p-4 text-left transition hover:-translate-y-0.5 hover:border-primary-300 hover:shadow-pop"
                >
                  <span className="grid h-10 w-10 shrink-0 place-items-center rounded-xl bg-primary-900 text-sm font-semibold text-paper-50">
                    {ws.name.trim().slice(0, 1).toUpperCase()}
                  </span>
                  <span className="min-w-0 flex-1">
                    <span className="block truncate text-sm font-medium text-ink-900">{ws.name}</span>
                    <span className="mt-0.5 block text-2xs text-ink-400">
                      {roleLabel(ws.role)} · {ws.plan === "free" ? "免费版" : ws.plan}
                    </span>
                  </span>
                  <ChevronRight
                    size={16}
                    className="shrink-0 text-ink-300 transition group-hover:translate-x-0.5 group-hover:text-primary-500"
                  />
                </button>
              ))}

              {creating ? (
                <form
                  onSubmit={createWorkspace}
                  className="card space-y-3 border-clay-500/30 p-4 sm:col-span-2 xl:col-span-1"
                >
                  <div className="flex items-center gap-2">
                    <span className="grid h-6 w-6 place-items-center rounded-md bg-clay-50 text-clay-600">
                      <Plus size={14} />
                    </span>
                    <span className="text-sm font-medium text-ink-800">新建工作区</span>
                  </div>
                  <Field label="名称">
                    <input
                      className="input"
                      placeholder="例如：达道科技 / 我的事项"
                      value={name}
                      maxLength={64}
                      autoFocus
                      onChange={(e) => setName(e.target.value)}
                    />
                  </Field>
                  {error && <InlineAlert>{error}</InlineAlert>}
                  <div className="flex items-center gap-2">
                    <Button type="submit" variant="primary" size="sm" disabled={busy || !name.trim()}>
                      {busy ? "创建中…" : "创建"}
                      {busy ? null : <ArrowRight size={14} />}
                    </Button>
                    <Button
                      type="button"
                      variant="ghost"
                      size="sm"
                      onClick={() => {
                        setCreating(false);
                        setError(null);
                      }}
                    >
                      取消
                    </Button>
                  </div>
                </form>
              ) : (
                <button
                  onClick={() => setCreating(true)}
                  className="flex min-h-[92px] items-center justify-center gap-2 rounded-xl border border-dashed border-line-300 text-sm text-ink-400 transition hover:border-primary-300 hover:text-primary-600"
                >
                  <Plus size={16} />
                  新建工作区
                </button>
              )}

              {workspaces.length === 0 && !creating ? (
                <div className="card sm:col-span-2 xl:col-span-3">
                  <EmptyState
                    icon={<Plus size={18} />}
                    title="还没有工作区"
                    hint="个人用也一样：先建一个，把「任务」放进去。需要别人帮忙时再升级成工单。"
                  />
                </div>
              ) : null}
            </div>
          )}

          <p className="mt-6 text-2xs leading-relaxed text-ink-400">
            收到邀请链接（<span className="font-mono">/join/…</span>）直接打开即可加入，不需要别人手动拉你。
          </p>
        </div>
      </main>
    </div>
  );
}