"use client";

import { useEffect, useMemo, useRef, useState } from "react";
import Link from "next/link";
import { useRouter, useSearchParams } from "next/navigation";
import { ArrowLeft, Copy, ExternalLink, Loader2 } from "lucide-react";
import {
  apiAdminCreateAnnouncement,
  apiAdminUpdateAnnouncement,
  type Announcement,
  type AnnouncementColor,
  type AnnouncementInput,
} from "@/lib/api";
import { toast } from "@/lib/toast";
import MarkdownEditor from "@/components/MarkdownEditor";
import { AdminField, AdminSegmented, AdminStatusChip, AdminSwitch } from "@/components/admin";
import ConfirmDialog from "@/components/ConfirmDialog";
import useUnsavedGuard from "@/hooks/useUnsavedGuard";
import { ANNOUNCEMENT_COLORS, announcementPublicPath } from "./announcementColors";

type PublishKey = "published" | "draft";
type StatusFilter = "all" | "published" | "draft";

type FormState = {
  title: string;
  content: string;
  tag: string;
  tag_color: AnnouncementColor;
  published: boolean;
  pinned: boolean;
};

type FieldErrors = {
  title?: string;
  content?: string;
  tag?: string;
  tag_color?: string;
  form?: string;
};

function toForm(a?: Announcement | null): FormState {
  return {
    title: a?.title ?? "",
    content: a?.content ?? "",
    tag: a?.tag ?? "公告",
    tag_color: a?.tag_color ?? "blue",
    published: a?.published ?? true,
    pinned: a?.pinned ?? false,
  };
}

function sameForm(a: FormState, b: FormState): boolean {
  return (
    a.title === b.title &&
    a.content === b.content &&
    a.tag === b.tag &&
    a.tag_color === b.tag_color &&
    a.published === b.published &&
    a.pinned === b.pinned
  );
}

function runeCount(s: string): number {
  return Array.from(s).length;
}

function validate(form: FormState): FieldErrors {
  const errors: FieldErrors = {};
  const title = form.title.trim();
  if (!title) errors.title = "标题不能为空";
  else if (runeCount(title) > 200) errors.title = "标题不能超过 200 字";

  if (!form.content.trim()) errors.content = "内容不能为空";

  const tag = form.tag.trim();
  if (tag && runeCount(tag) > 32) errors.tag = "标签不能超过 32 字";
  return errors;
}

function errorsFromServer(msg: string): FieldErrors {
  if (msg.includes("标题")) return { title: msg };
  if (msg.includes("颜色")) return { tag_color: msg };
  if (msg.includes("标签")) return { tag: msg };
  if (msg.includes("内容") || msg.includes("隐藏") || msg.includes("回复")) return { content: msg };
  return { form: msg };
}

function hasErrors(errors: FieldErrors): boolean {
  return Object.values(errors).some(Boolean);
}

function readStatus(raw: string | null): StatusFilter {
  if (raw === "published" || raw === "draft") return raw;
  return "all";
}

function listHref(status: StatusFilter): string {
  return status === "all" ? "/admin/announcements" : `/admin/announcements?status=${status}`;
}

function primaryLabel(savedPublished: boolean | null, targetPublished: boolean): string {
  if (savedPublished !== true && !targetPublished) return "保存草稿";
  if (savedPublished !== true && targetPublished) return "发布公告";
  if (savedPublished && targetPublished) return "保存并更新";
  return "转为草稿";
}

export default function AnnouncementComposeClient({
  mode,
  initial,
}: {
  mode: "create" | "edit";
  initial?: Announcement | null;
}) {
  const router = useRouter();
  const searchParams = useSearchParams();
  const status = readStatus(searchParams.get("status"));
  const backHref = listHref(status);
  const loaded = useMemo(() => toForm(initial), [initial]);
  const [baseline, setBaseline] = useState<FormState>(loaded);
  const [saved, setSaved] = useState<Announcement | null>(initial ?? null);
  const [form, setForm] = useState<FormState>(loaded);
  const formRef = useRef(form);
  const [saving, setSaving] = useState(false);
  const [errors, setErrors] = useState<FieldErrors>({});
  const [origin, setOrigin] = useState("");
  const [confirmUnpublish, setConfirmUnpublish] = useState(false);
  const isEdit = mode === "edit" && saved != null;
  const dirty = !sameForm(form, baseline);
  const { leaveOpen, confirmLeave, cancelLeave } = useUnsavedGuard(dirty && !saving);
  const savedPublished = isEdit ? baseline.published : null;

  useEffect(() => {
    setOrigin(window.location.origin);
  }, []);

  const patchForm = (patch: Partial<FormState> | ((prev: FormState) => FormState)) => {
    setForm((prev) => {
      const next = typeof patch === "function" ? patch(prev) : { ...prev, ...patch };
      formRef.current = next;
      return next;
    });
  };

  const canViewOnline = saved?.published === true && saved.id > 0;
  const publicPath = saved ? announcementPublicPath(saved.id) : "";

  async function commit() {
    if (saving) return;
    const current = formRef.current;
    const payload: AnnouncementInput = {
      title: current.title.trim(),
      content: current.content.trim(),
      tag: current.tag.trim() || "公告",
      tag_color: current.tag_color,
      published: current.published,
      pinned: current.pinned,
    };
    setSaving(true);
    setErrors({});
    try {
      if (isEdit && saved) {
        const res = await apiAdminUpdateAnnouncement(saved.id, payload);
        const nextItem = res.announcement;
        const next = toForm(nextItem);
        const wasPublished = baseline.published;
        formRef.current = next;
        setForm(next);
        setBaseline(next);
        setSaved(nextItem);
        const nowPublished = nextItem.published;
        const msg = !wasPublished && nowPublished
          ? "公告已发布"
          : wasPublished && !nowPublished
            ? "已转为草稿"
            : wasPublished
              ? "公告已更新"
              : "草稿已保存";
        toast(msg, "ok");
        router.refresh();
      } else {
        const res = await apiAdminCreateAnnouncement(payload);
        toast(payload.published ? "公告已发布" : "草稿已保存", "ok");
        const id = res.announcement?.id;
        if (id) {
          const q = status === "all" ? "" : `?status=${status}`;
          router.replace(`/admin/announcements/${id}/edit${q}`);
        } else {
          router.push(backHref);
        }
        router.refresh();
      }
    } catch (e) {
      const msg = e instanceof Error ? e.message : "保存失败";
      setErrors(errorsFromServer(msg));
      toast(msg);
    } finally {
      setSaving(false);
      setConfirmUnpublish(false);
    }
  }

  function requestSave() {
    if (saving) return;
    const current = formRef.current;
    const nextErrors = validate(current);
    if (hasErrors(nextErrors)) {
      setErrors(nextErrors);
      toast("请先修正标出的字段");
      return;
    }
    if (isEdit && baseline.published && !current.published) {
      setConfirmUnpublish(true);
      return;
    }
    void commit();
  }

  function discard() {
    formRef.current = baseline;
    setForm(baseline);
    setErrors({});
  }

  async function copyAddress() {
    if (!saved) return;
    const url = `${(origin || window.location.origin).replace(/\/$/, "")}${announcementPublicPath(saved.id)}`;
    try {
      await navigator.clipboard.writeText(url);
      toast("已复制访问地址", "ok");
    } catch {
      toast("复制失败");
    }
  }

  const saveLabel = primaryLabel(savedPublished, form.published);
  const statusText = saving
    ? "正在保存…"
    : errors.form
      ? errors.form
      : dirty
        ? "有未保存的修改"
        : isEdit
          ? "已保存"
          : "尚未保存";

  return (
    <div className="admin-doc-page admin-doc-editor">
      <header className="admin-doc-head">
        <div className="min-w-0">
          <Link href={backHref} className="admin-doc-back">
            <ArrowLeft size={14} aria-hidden /> 返回列表
          </Link>
          <div className="admin-doc-head-title">
            <h1>{isEdit ? "编辑公告" : "新建公告"}</h1>
            <AdminStatusChip tone={savedPublished ? "ok" : savedPublished === false ? "warn" : "accent"}>
              {savedPublished ? "已发布" : savedPublished === false ? "草稿" : "尚未保存"}
            </AdminStatusChip>
          </div>
        </div>
        {canViewOnline ? (
          <a
            href={publicPath}
            target="_blank"
            rel="noopener noreferrer"
            className="btn btn-line"
            title="打开已发布内容。未保存的修改不会出现在这里。"
          >
            <ExternalLink size={14} aria-hidden /> 查看线上页面
          </a>
        ) : null}
      </header>

      <div className="admin-doc-split">
        <div className="admin-doc-main">
          <AdminField
            id="anno-title"
            label="标题"
            maxLength={200}
            value={form.title}
            error={errors.title}
            onChange={(title) => {
              setErrors((prev) => ({ ...prev, title: undefined }));
              patchForm({ title });
            }}
            placeholder="请输入公告标题"
          />
          <div className="admin-doc-md">
            <label className="admin-doc-label" htmlFor="anno-content">
              正文
            </label>
            <MarkdownEditor
              id="anno-content"
              value={form.content}
              onChange={(content) => {
                setErrors((prev) => ({ ...prev, content: undefined }));
                patchForm({ content });
              }}
              allowHide
              allowReplyHide={false}
              placeholder="请输入公告正文，支持 Markdown…"
              rows={16}
              onSubmitShortcut={requestSave}
            />
            {errors.content ? (
              <p className="admin-settings-row-error" role="alert">
                {errors.content}
              </p>
            ) : null}
          </div>
        </div>

        <details className="admin-doc-rail" open>
          <summary>公告设置</summary>
          <div className="admin-doc-rail-body">
            <AdminField
              id="anno-tag"
              label="标签"
              hint="显示在首页右栏和公告列表的标题旁。留空保存时会写成「公告」。"
              maxLength={32}
              value={form.tag}
              error={errors.tag}
              onChange={(tag) => {
                setErrors((prev) => ({ ...prev, tag: undefined }));
                patchForm({ tag });
              }}
              placeholder="公告"
            />

            <div className="admin-doc-field">
              <p className="admin-doc-label">标签颜色</p>
              <div className="admin-doc-colors" role="radiogroup" aria-label="标签颜色">
                {ANNOUNCEMENT_COLORS.map((c) => (
                  <button
                    key={c.value}
                    type="button"
                    role="radio"
                    aria-checked={form.tag_color === c.value}
                    data-tip={c.label}
                    aria-label={c.label}
                    className={`j13-anno-dot is-${c.value}`}
                    onClick={() => patchForm({ tag_color: c.value })}
                  />
                ))}
              </div>
              <p className="admin-doc-hint">只影响标签颜色，不改正文。</p>
              {errors.tag_color ? (
                <p className="admin-settings-row-error" role="alert">
                  {errors.tag_color}
                </p>
              ) : null}
            </div>

            <div className="admin-doc-field">
              <p className="admin-doc-label">置顶</p>
              <div className="admin-doc-switchline">
                <AdminSwitch
                  checked={form.pinned}
                  onChange={() => patchForm((f) => ({ ...f, pinned: !f.pinned }))}
                  label="置顶公告"
                />
                <span>置顶公告</span>
              </div>
              <p className="admin-doc-hint">
                已发布且置顶的公告排在首页右栏前面。草稿即使勾选也不会出现在前台。
              </p>
            </div>

            {isEdit && saved ? (
              <div className="admin-doc-field">
                <p className="admin-doc-label">访问地址</p>
                <p className="admin-doc-hint">
                  {publicPath}
                  {origin ? ` · ${origin.replace(/\/$/, "")}${publicPath}` : ""}
                </p>
                <p className="admin-doc-hint">地址按公告编号生成，不能改成自定义路径。</p>
                <button type="button" className="btn btn-line admin-doc-copy" onClick={() => void copyAddress()}>
                  <Copy size={14} aria-hidden /> 复制地址
                </button>
              </div>
            ) : (
              <p className="admin-doc-hint">保存后才会有公开地址 /announcement/编号。草稿没有公开入口。</p>
            )}

            <div className="admin-doc-field">
              <p className="admin-doc-label">保存后状态</p>
              <AdminSegmented<PublishKey>
                role="group"
                ariaLabel="保存后状态"
                size="sm"
                value={form.published ? "published" : "draft"}
                onChange={(key) => patchForm({ published: key === "published" })}
                options={[
                  { key: "draft", label: "草稿" },
                  { key: "published", label: "已发布" },
                ]}
              />
              <p className="admin-doc-hint">点选只改变这次要保存的状态，不会立刻发布或下线。</p>
            </div>
          </div>
        </details>

        <div className="admin-doc-actions" aria-busy={saving || undefined}>
          <div className="admin-doc-actions-btns">
            <button type="button" className="btn btn-line" disabled={!dirty || saving} onClick={discard}>
              撤销修改
            </button>
            <button
              type="button"
              className="btn btn-primary"
              disabled={!dirty || saving}
              onClick={requestSave}
            >
              {saving ? <Loader2 size={15} className="animate-spin" aria-hidden /> : null}
              {saving ? "保存中…" : saveLabel}
            </button>
            <p className={`admin-doc-status${errors.form ? " is-error" : ""}`} aria-live="polite">
              {statusText}
            </p>
          </div>
          <p className="admin-doc-hint">一次保存会写入标题、正文和公告设置。Ctrl/⌘ + Enter 与这个按钮相同。</p>
          {canViewOnline ? (
            <p className="admin-doc-hint">查看线上页面打开的是已发布内容，未保存的修改不会出现在那里。</p>
          ) : (
            <p className="admin-doc-hint">草稿没有公开地址。要看正文，用编辑器里的预览。</p>
          )}
        </div>
      </div>

      <ConfirmDialog
        open={leaveOpen}
        title="有未保存的修改"
        message="离开后，尚未写入的修改会丢失。确定离开？"
        confirmLabel="离开"
        danger
        onCancel={cancelLeave}
        onConfirm={confirmLeave}
      />
      <ConfirmDialog
        open={confirmUnpublish}
        title="转为草稿"
        message="转为草稿后，前台将无法打开此公告。这里没有单独的修订版本，线上内容会一起下线，不会保留旧版。"
        confirmLabel="转为草稿"
        danger
        busy={saving}
        onCancel={() => {
          if (!saving) setConfirmUnpublish(false);
        }}
        onConfirm={() => void commit()}
      />
    </div>
  );
}