// ── Zustand Store for Routines ────────────────────────────────
import { create } from 'zustand';
import { persist, createJSONStorage } from 'zustand/middleware';
import type { Routine, CreateRoutineParams } from './routines';
import {
  createRoutine,
  startRoutine,
  pauseRoutine,
  resumeRoutine,
  completeCurrentStep,
  skipCurrentStep,
  cancelRoutine,
  instantiateTemplate,
  getBuiltInTemplates,
  shouldStepComplete,
} from './routines';
import { enqueueRoutineChange, enqueueRoutineDeleteChange, isSyncEnabled } from './platform-sync';

export interface RoutineStore {
  routines: Routine[];
  templates: Routine[];

  // CRUD
  addRoutine: (params: CreateRoutineParams) => Routine;
  addTemplate: (params: CreateRoutineParams) => Routine;
  removeRoutine: (id: string) => void;
  removeTemplate: (id: string) => void;

  // State transitions
  start: (id: string) => void;
  pause: (id: string) => void;
  resume: (id: string) => void;
  completeStep: (id: string) => void;
  skipStep: (id: string) => void;
  cancel: (id: string) => void;

  // Template
  startFromTemplate: (templateId: string) => Routine | null;

  // Tick — auto-advance steps
  tickRoutines: (now: number) => void;

  // Helpers
  getRoutine: (id: string) => Routine | undefined;
  getActiveRoutine: () => Routine | undefined;
}

function updateRoutine(routines: Routine[], id: string, updater: (r: Routine) => Routine): Routine[] {
  return routines.map((r) => (r.id === id ? updater(r) : r));
}

export const useRoutineStore = create<RoutineStore>()(
  persist(
    (set, get) => ({
      routines: [],
      templates: getBuiltInTemplates(),

      addRoutine: (params) => {
        const routine = createRoutine(params);
        set((s) => ({ routines: [...s.routines, routine] }));
        if (isSyncEnabled()) enqueueRoutineChange(routine, 'create');
        return routine;
      },

      addTemplate: (params) => {
        const template = createRoutine({ ...params, isTemplate: true });
        set((s) => ({ templates: [...s.templates, template] }));
        return template;
      },

      removeRoutine: (id) => {
        set((s) => ({ routines: s.routines.filter((r) => r.id !== id) }));
        if (isSyncEnabled()) enqueueRoutineDeleteChange(id);
      },

      removeTemplate: (id) => {
        set((s) => ({ templates: s.templates.filter((r) => r.id !== id) }));
      },

      start: (id) => {
        set((s) => ({ routines: updateRoutine(s.routines, id, startRoutine) }));
        const updated = get().routines.find((r) => r.id === id);
        if (updated && isSyncEnabled()) enqueueRoutineChange(updated, 'update');
      },

      pause: (id) => {
        set((s) => ({ routines: updateRoutine(s.routines, id, pauseRoutine) }));
        const updated = get().routines.find((r) => r.id === id);
        if (updated && isSyncEnabled()) enqueueRoutineChange(updated, 'update');
      },

      resume: (id) => {
        set((s) => ({ routines: updateRoutine(s.routines, id, resumeRoutine) }));
        const updated = get().routines.find((r) => r.id === id);
        if (updated && isSyncEnabled()) enqueueRoutineChange(updated, 'update');
      },

      completeStep: (id) => {
        set((s) => ({ routines: updateRoutine(s.routines, id, completeCurrentStep) }));
        const updated = get().routines.find((r) => r.id === id);
        if (updated && isSyncEnabled()) enqueueRoutineChange(updated, 'update');
      },

      skipStep: (id) => {
        set((s) => ({ routines: updateRoutine(s.routines, id, skipCurrentStep) }));
        const updated = get().routines.find((r) => r.id === id);
        if (updated && isSyncEnabled()) enqueueRoutineChange(updated, 'update');
      },

      cancel: (id) => {
        set((s) => ({ routines: updateRoutine(s.routines, id, cancelRoutine) }));
        const updated = get().routines.find((r) => r.id === id);
        if (updated && isSyncEnabled()) enqueueRoutineChange(updated, 'update');
      },

      startFromTemplate: (templateId) => {
        const template = get().templates.find((t) => t.id === templateId);
        if (!template) return null;
        const routine = startRoutine(instantiateTemplate(template));
        set((s) => ({ routines: [...s.routines, routine] }));
        if (isSyncEnabled()) enqueueRoutineChange(routine, 'create');
        return routine;
      },

      tickRoutines: (now) => {
        const { routines } = get();
        let changed = false;
        const updated = routines.map((r) => {
          if (r.status === 'active' && shouldStepComplete(r, now)) {
            changed = true;
            return completeCurrentStep(r);
          }
          return r;
        });
        if (changed) set({ routines: updated });
      },

      getRoutine: (id) => get().routines.find((r) => r.id === id),

      getActiveRoutine: () => get().routines.find((r) => r.status === 'active' || r.status === 'paused'),
    }),
    {
      name: 'chronomind-routines',
      storage: createJSONStorage(() => {
        if (typeof window === 'undefined') {
          return { getItem: () => null, setItem: () => {}, removeItem: () => {} };
        }
        return localStorage;
      }),
      partialize: (state) => ({ routines: state.routines, templates: state.templates }),
    }
  )
);