import { create } from 'zustand';

export interface Tab { id: string; path: string; pinned: boolean; scrollTop: number; }

interface TabState {
  tabs: Tab[];
  activeId: string | null;
  openTab: (path: string) => void;
  closeTab: (id: string) => void;
  setActive: (id: string) => void;
  togglePin: (id: string) => void;
  updateScroll: (id: string, scrollTop: number) => void; // FR-T5：保存滚动位置
  closeAll: () => void;            // FR-V6: 切库时清空全部标签页
  renamePath: (oldPath: string, newPath: string) => void; // FR-T7: 重命名/移动后同步标签页路径
  activePath: () => string | null;
  persist: () => void;
  restore: () => void;
}

const SESSION_KEY = 'dsh-session';

export const useTabs = create<TabState>((set, get) => ({
  tabs: [],
  activeId: null,

  openTab: (path) => {
    const existing = get().tabs.find(t => t.path === path);
    if (existing) { set({ activeId: existing.id }); return; }
    const id = 'tab-' + Date.now() + '-' + Math.random().toString(36).slice(2, 6);
    set(s => ({ tabs: [...s.tabs, { id, path, pinned: false, scrollTop: 0 }], activeId: id }));
    get().persist();
  },

  closeTab: (id) => {
    const { tabs, activeId } = get();
    const idx = tabs.findIndex(t => t.id === id);
    const remaining = tabs.filter(t => t.id !== id);
    let newActive = activeId;
    if (activeId === id) {
      // 切到相邻（优先未固定的相邻）
      const neighbor = remaining[idx] ?? remaining[idx - 1] ?? remaining[remaining.length - 1];
      newActive = neighbor?.id ?? null;
    }
    set({ tabs: remaining, activeId: newActive });
    get().persist();
  },

  setActive: (id) => { set({ activeId: id }); get().persist(); },

  // FR-T5：更新标签页滚动位置（不触发 persist，避免频繁写入）
  updateScroll: (id, scrollTop) => {
    set(s => ({ tabs: s.tabs.map(t => t.id === id ? { ...t, scrollTop } : t) }));
  },

  togglePin: (id) => {
    set(s => {
      const tabs = s.tabs.map(t => t.id === id ? { ...t, pinned: !t.pinned } : t);
      // 固定的排前
      tabs.sort((a, b) => (a.pinned === b.pinned ? 0 : a.pinned ? -1 : 1));
      return { tabs };
    });
    get().persist();
  },

  closeAll: () => { set({ tabs: [], activeId: null }); get().persist(); },

  renamePath: (oldPath, newPath) => {
    set(s => ({
      tabs: s.tabs.map(t => {
        if (t.path === oldPath) return { ...t, path: newPath };
        // 文件夹重命名/移动：子文档标签页路径前缀替换
        if (oldPath && t.path.startsWith(oldPath + '/')) return { ...t, path: newPath + t.path.slice(oldPath.length) };
        return t;
      }),
    }));
    get().persist();
  },

  activePath: () => { const { tabs, activeId } = get(); return tabs.find(t => t.id === activeId)?.path ?? null; },

  persist: () => {
    const { tabs, activeId } = get();
    try { localStorage.setItem(SESSION_KEY, JSON.stringify({ tabs, activeId })); } catch {}
  },

  restore: () => {
    try {
      const raw = localStorage.getItem(SESSION_KEY);
      if (!raw) return;
      const saved = JSON.parse(raw);
      set({ tabs: saved.tabs ?? [], activeId: saved.activeId ?? null });
    } catch {}
  },
}));