import fs from 'node:fs/promises';
import path from 'node:path';
import type { ControlPlaneState } from '../../src/shared/contracts';
import { createDefaultState } from './config';

export class StateStore {
  constructor(private readonly statePath: string) {}

  async read(): Promise<ControlPlaneState> {
    await fs.mkdir(path.dirname(this.statePath), { recursive: true });

    try {
      const raw = await fs.readFile(this.statePath, 'utf8');
      const state = JSON.parse(raw) as ControlPlaneState;
      const migrated = migrateLegacyAdminServices(state);

      if (migrated !== state) {
        await this.write(migrated);
      }

      return migrated;
    } catch (error) {
      if ((error as NodeJS.ErrnoException).code !== 'ENOENT') {
        throw error;
      }

      const fallback = createDefaultState();
      await this.write(fallback);
      return fallback;
    }
  }

  async write(state: ControlPlaneState): Promise<void> {
    await fs.mkdir(path.dirname(this.statePath), { recursive: true });
    await fs.writeFile(this.statePath, `${JSON.stringify(state, null, 2)}\n`, 'utf8');
  }
}

function migrateLegacyAdminServices(state: ControlPlaneState): ControlPlaneState {
  const legacyServiceIds = new Set(
    state.system.services
      .filter((service) => (service as { command?: unknown }).command === 'admin')
      .map((service) => service.id),
  );

  if (legacyServiceIds.size === 0) {
    return state;
  }

  return {
    ...state,
    service: {
      ...state.service,
      lastEvent: 'Legacy admin service removed from stored panel state',
    },
    userRecords: state.userRecords.filter((user) => !legacyServiceIds.has(user.serviceId)),
    system: {
      ...state.system,
      services: state.system.services.filter((service) => !legacyServiceIds.has(service.id)),
    },
  };
}