'use client';
import { create } from 'zustand';
import type { DevTask, DevTaskStatus } from '@/lib/dev-task';
import { canTransition, generateTaskNo, isLegacyTask } from '@/lib/dev-task';
import { findTasksToAutoStart, deriveActualStartAt } from '@/lib/dev-task-transitions';

const STORAGE_KEY = 'ftb_dev_tasks_v2';
const LEGACY_KEY = 'ftb_dev_tasks_v1';

function saveLocal(items: DevTask[]) {
  try { localStorage.setItem(STORAGE_KEY, JSON.stringify(items)); } catch {}
}

function loadLocal(): DevTask[] | null {
  try {
    const raw = localStorage.getItem(STORAGE_KEY);
    if (raw) {
      const parsed = JSON.parse(raw);
      if (Array.isArray(parsed) && parsed.some(isLegacyTask)) {
        localStorage.removeItem(STORAGE_KEY);
        return null;
      }
      return parsed;
    }
    if (localStorage.getItem(LEGACY_KEY)) {
      localStorage.removeItem(LEGACY_KEY);
    }
  } catch {}
  return null;
}

interface DevTaskState {
  tasks: DevTask[];
  fetchTasks: () => void;
  createTask: (data: Omit<DevTask, 'id' | 'taskNo' | 'createdAt' | 'updatedAt' | 'isBlocked'>) => DevTask;
  updateTask: (id: string, data: Partial<DevTask>) => void;
  deleteTask: (id: string) => void;
  changeStatus: (id: string, to: DevTaskStatus, opts?: { delayReason?: string }) => { ok: boolean; message?: string };
  setBlocked: (id: string, blocked: boolean, reason?: string, blockedById?: string) => void;
  getByRequirement: (requirementId: string) => DevTask[];
  getByVersionViaRequirements: (requirementIds: string[]) => DevTask[];
  getByAssignee: (assigneeId: string) => DevTask[];
}

export const useDevTaskStore = create<DevTaskState>((set, get) => ({
  tasks: [],

  fetchTasks: () => {
    const cached = loadLocal();
    const list = cached ?? [];
    const now = new Date();
    const autoStarts = findTasksToAutoStart(list, now);
    if (autoStarts.length > 0) {
      const map = new Map(autoStarts.map((a) => [a.taskId, a.actualStartAt]));
      const updated = list.map((t) =>
        map.has(t.id)
          ? { ...t, status: 'in_progress' as DevTaskStatus, actualStartAt: map.get(t.id)!, updatedAt: now.toISOString() }
          : t,
      );
      set({ tasks: updated });
      saveLocal(updated);
    } else {
      set({ tasks: list });
    }
  },

  createTask: (data) => {
    const list = get().tasks;
    const now = new Date().toISOString();
    const task: DevTask = {
      ...data,
      id: `task-${Date.now()}`,
      taskNo: generateTaskNo(list),
      isBlocked: false,
      createdAt: now,
      updatedAt: now,
    };
    const updated = [...list, task];
    set({ tasks: updated });
    saveLocal(updated);
    return task;
  },

  updateTask: (id, data) => {
    const updated = get().tasks.map((t) =>
      t.id === id ? { ...t, ...data, updatedAt: new Date().toISOString() } : t,
    );
    set({ tasks: updated });
    saveLocal(updated);
  },

  deleteTask: (id) => {
    const updated = get().tasks.filter((t) => t.id !== id);
    set({ tasks: updated });
    saveLocal(updated);
  },

  changeStatus: (id, to, opts) => {
    const task = get().tasks.find((t) => t.id === id);
    if (!task) return { ok: false, message: '任务不存在' };
    if (!canTransition(task.status, to)) {
      return { ok: false, message: `不允许从「${task.status}」流转到「${to}」` };
    }
    const now = new Date();
    const patch: Partial<DevTask> = { status: to };
    if (to === 'in_progress' && !task.actualStartAt) {
      patch.actualStartAt = deriveActualStartAt(task, 'manual', now);
      if (opts?.delayReason) patch.delayReason = opts.delayReason;
    }
    if (to === 'submitted') {
      patch.actualEndAt = now.toISOString();
    }
    get().updateTask(id, patch);
    return { ok: true };
  },

  setBlocked: (id, blocked, reason, blockedById) => {
    get().updateTask(id, {
      isBlocked: blocked,
      blockReason: blocked ? reason : undefined,
      blockedById: blocked ? blockedById : undefined,
    });
  },

  getByRequirement: (requirementId) => {
    return get().tasks.filter((t) => t.requirementId === requirementId);
  },

  getByVersionViaRequirements: (requirementIds) => {
    const idSet = new Set(requirementIds);
    return get().tasks.filter((t) => idSet.has(t.requirementId));
  },

  getByAssignee: (assigneeId) => {
    return get().tasks.filter((t) => t.assigneeId === assigneeId);
  },
}));