import {
  ZabbixConfig,
  ZabbixHost,
  ZabbixHostGroup,
  ZabbixTemplate,
  ZabbixHostCreateParams,
  ZabbixHostUpdateParams,
  ZabbixRpcResponse,
} from '@/lib/types/zabbix';

export type { ZabbixHostTag } from '@/lib/types/zabbix';

export class ZabbixClient {
  private config: ZabbixConfig;
  private rpcId = 0;

  constructor(config: ZabbixConfig) {
    this.config = config;
  }

  /**
   * Make a JSON-RPC 2.0 call to the Zabbix API.
   * Auth is stateless: Bearer token in Authorization header (Zabbix 6.0+ API token).
   */
  private async rpc<T>(method: string, params: Record<string, any>): Promise<T> {
    const id = ++this.rpcId;
    const url = `${this.config.apiUrl.replace(/\/$/, '')}/api_jsonrpc.php`;

    const body = JSON.stringify({
      jsonrpc: '2.0',
      method,
      params,
      id,
    });

    const response = await fetch(url, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${this.config.apiToken}`,
      },
      body,
    });

    if (!response.ok) {
      const text = await response.text();
      throw new Error(`Zabbix HTTP ${response.status}: ${text.substring(0, 200)}`);
    }

    const data: ZabbixRpcResponse<T> = await response.json();

    if (data.error) {
      throw new Error(
        `Zabbix RPC error (${data.error.code}): ${data.error.message}` +
        (data.error.data ? ` — ${data.error.data}` : '')
      );
    }

    return data.result as T;
  }

  /**
   * Get or create a host group by name. Returns the groupid.
   */
  async ensureHostGroup(name: string): Promise<string> {
    const existing = await this.rpc<ZabbixHostGroup[]>('hostgroup.get', {
      output: ['groupid', 'name'],
      filter: { name: [name] },
    });

    if (existing.length > 0) {
      return existing[0].groupid;
    }

    const created = await this.rpc<{ groupids: string[] }>('hostgroup.create', {
      name,
    });

    return created.groupids[0];
  }

  /**
   * Find a template by exact or partial host name. Returns the first match or null.
   */
  async findTemplate(name: string): Promise<ZabbixTemplate | null> {
    const results = await this.rpc<ZabbixTemplate[]>('template.get', {
      output: ['templateid', 'host', 'name'],
      search: { host: name },
      searchByAny: false,
    });

    return results.length > 0 ? results[0] : null;
  }

  /**
   * Find a host by its technical name (host field), with a fallback search by
   * display name. The fallback handles legacy hosts created before hostname
   * sanitization was introduced (their host == name == full display string).
   */
  async findHostByName(hostname: string, displayName?: string): Promise<ZabbixHost | null> {
    const results = await this.rpc<ZabbixHost[]>('host.get', {
      output: ['hostid', 'host', 'name', 'status'],
      filter: { host: [hostname] },
    });
    if (results.length > 0) return results[0];

    // Fallback: search by display name (catches pre-sanitization legacy hosts)
    if (displayName && displayName !== hostname) {
      const byName = await this.rpc<ZabbixHost[]>('host.get', {
        output: ['hostid', 'host', 'name', 'status'],
        filter: { name: [displayName] },
      });
      if (byName.length > 0) return byName[0];
    }

    return null;
  }

  /**
   * Create or update a Zabbix host. Idempotent — looks up by host name first.
   * Returns the hostid and whether the host was created or updated.
   */
  async upsertHost(params: ZabbixHostCreateParams): Promise<{
    action: 'created' | 'updated';
    hostid: string;
  }> {
    const existing = await this.findHostByName(params.host, params.name);

    if (!existing) {
      const result = await this.rpc<{ hostids: string[] }>('host.create', params);
      return { action: 'created', hostid: result.hostids[0] };
    }

    const updateParams: ZabbixHostUpdateParams = {
      hostid: existing.hostid,
      name: params.name,
      description: params.description,
      // Do not pass interfaces on update — Zabbix rejects changes when items
      // are already linked to the existing interface.
      groups: params.groups,
      templates: params.templates,
      macros: params.macros,
      tags: params.tags,
    };

    await this.rpc<{ hostids: string[] }>('host.update', updateParams);
    return { action: 'updated', hostid: existing.hostid };
  }
}