/**
 * InMemoryGmailClient — deterministic in-memory GmailClient for local dev.
 *
 * Holds a small set of FAKE inboxes/threads in memory, partitioned by userSub
 * so a user only ever sees their own mail. searchInbox does a simple
 * case-insensitive substring match against subject/snippet; getThreadDetail
 * throws if the thread is not found or not owned by the caller. No network.
 *
 * This is for build-plan §4 "in-memory dev clients (tools return real data
 * locally)".
 */

import type {
  EmailMessage,
  EmailThread,
  GetThreadDetailParams,
  GmailClient,
  SearchInboxParams,
} from './client.js';

interface SeedInbox {
  messages: EmailMessage[];
  threads: Map<string, EmailThread>;
}

function seedInboxes(): Map<string, SeedInbox> {
  const map = new Map<string, SeedInbox>();

  map.set('lauren@seahavenind.com', {
    messages: [
      {
        id: 'msg-l-1',
        threadId: 'thr-l-1',
        subject: 'Invoice #4821 from Coastal Supply',
        from: 'billing@coastalsupply.example',
        to: 'lauren@seahavenind.com',
        date: '2026-06-22T09:15:00Z',
        snippet: 'Please find attached invoice #4821 for the dock hardware order.',
      },
      {
        id: 'msg-l-2',
        threadId: 'thr-l-2',
        subject: 'Re: Site walkthrough scheduling',
        from: 'adam@seahavenind.com',
        to: 'lauren@seahavenind.com',
        date: '2026-06-23T14:02:00Z',
        snippet: 'Friday afternoon works for the marina pier walkthrough.',
      },
    ],
    threads: new Map<string, EmailThread>([
      [
        'thr-l-1',
        {
          threadId: 'thr-l-1',
          subject: 'Invoice #4821 from Coastal Supply',
          messages: [
            {
              id: 'msg-l-1',
              from: 'billing@coastalsupply.example',
              to: 'lauren@seahavenind.com',
              date: '2026-06-22T09:15:00Z',
              body: 'Please find attached invoice #4821 for the dock hardware order. Net 30 terms apply.',
            },
          ],
        },
      ],
      [
        'thr-l-2',
        {
          threadId: 'thr-l-2',
          subject: 'Re: Site walkthrough scheduling',
          messages: [
            {
              id: 'msg-l-2',
              from: 'adam@seahavenind.com',
              to: 'lauren@seahavenind.com',
              date: '2026-06-23T14:02:00Z',
              body: 'Friday afternoon works for the marina pier walkthrough. I will bring the punch list.',
            },
          ],
        },
      ],
    ]),
  });

  map.set('adam@seahavenind.com', {
    messages: [
      {
        id: 'msg-a-1',
        threadId: 'thr-a-1',
        subject: 'Payment confirmation — check #2087',
        from: 'ap@seahavenind.com',
        to: 'adam@seahavenind.com',
        date: '2026-06-21T11:40:00Z',
        snippet: 'Check #2087 to Harbor Electric has cleared.',
      },
    ],
    threads: new Map<string, EmailThread>([
      [
        'thr-a-1',
        {
          threadId: 'thr-a-1',
          subject: 'Payment confirmation — check #2087',
          messages: [
            {
              id: 'msg-a-1',
              from: 'ap@seahavenind.com',
              to: 'adam@seahavenind.com',
              date: '2026-06-21T11:40:00Z',
              body: 'Check #2087 to Harbor Electric has cleared. The payment dashboard is updated.',
            },
          ],
        },
      ],
    ]),
  });

  return map;
}

/** In-memory GmailClient. Inboxes are partitioned by userSub. */
export class InMemoryGmailClient implements GmailClient {
  private readonly inboxes: Map<string, SeedInbox>;

  constructor() {
    this.inboxes = seedInboxes();
  }

  async searchInbox(params: SearchInboxParams): Promise<EmailMessage[]> {
    const inbox = this.inboxes.get(params.userSub);
    if (!inbox) {
      return [];
    }
    const q = params.query.toLowerCase();
    const matches = inbox.messages.filter(
      (m) => m.subject.toLowerCase().includes(q) || m.snippet.toLowerCase().includes(q),
    );
    return matches.slice(0, params.maxResults);
  }

  async getThreadDetail(params: GetThreadDetailParams): Promise<EmailThread> {
    const inbox = this.inboxes.get(params.userSub);
    const thread = inbox?.threads.get(params.threadId);
    if (!thread) {
      throw new Error(`Thread ${params.threadId} not found for user ${params.userSub}`);
    }
    return thread;
  }
}