import { Injectable, Logger, OnModuleInit, OnModuleDestroy } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import axios from 'axios';
import { PlatformGraphqlService } from './platform/platform-graphql.service';

// On startup, registers this sidecar with the telephony dispatcher
// so Ozonetel events are routed to the correct sidecar by agentId.
//
// Flow:
//   1. Load agent list from platform (Agent entities in this workspace)
//   2. POST /api/supervisor/register to the dispatcher
//   3. Start heartbeat interval (every 30s)
//   4. On shutdown, DELETE /api/supervisor/register

const HEARTBEAT_INTERVAL_MS = 30_000;

@Injectable()
export class TelephonyRegistrationService implements OnModuleInit, OnModuleDestroy {
    private readonly logger = new Logger(TelephonyRegistrationService.name);
    private heartbeatTimer: NodeJS.Timeout | null = null;

    constructor(
        private config: ConfigService,
        private platform: PlatformGraphqlService,
    ) {}

    private get dispatcherUrl(): string {
        return this.config.get<string>('TELEPHONY_DISPATCHER_URL') ?? '';
    }

    private get sidecarUrl(): string {
        return this.config.get<string>('TELEPHONY_CALLBACK_URL') ?? '';
    }

    private get workspace(): string {
        return process.env.PLATFORM_WORKSPACE_SUBDOMAIN ?? 'unknown';
    }

    async onModuleInit() {
        if (!this.dispatcherUrl || !this.sidecarUrl) {
            this.logger.warn('TELEPHONY_DISPATCHER_URL or TELEPHONY_CALLBACK_URL not set — skipping telephony registration');
            return;
        }

        await this.register();

        this.heartbeatTimer = setInterval(async () => {
            try {
                await axios.post(`${this.dispatcherUrl}/api/supervisor/heartbeat`, {
                    sidecarUrl: this.sidecarUrl,
                }, { timeout: 5000 });
            } catch (err: any) {
                this.logger.warn(`Heartbeat failed: ${err.message} — attempting re-registration`);
                await this.register();
            }
        }, HEARTBEAT_INTERVAL_MS);
    }

    async onModuleDestroy() {
        if (this.heartbeatTimer) clearInterval(this.heartbeatTimer);

        if (this.dispatcherUrl && this.sidecarUrl) {
            try {
                await axios.delete(`${this.dispatcherUrl}/api/supervisor/register`, {
                    data: { sidecarUrl: this.sidecarUrl },
                    timeout: 5000,
                });
                this.logger.log('Deregistered from telephony dispatcher');
            } catch {
                // Best-effort — TTL will clean up anyway
            }
        }
    }

    private async register() {
        try {
            const agents = await this.loadAgentIds();
            if (agents.length === 0) {
                this.logger.warn('No agents found in workspace — skipping registration');
                return;
            }

            await axios.post(`${this.dispatcherUrl}/api/supervisor/register`, {
                sidecarUrl: this.sidecarUrl,
                workspace: this.workspace,
                agents,
            }, { timeout: 5000 });

            this.logger.log(`Registered with telephony dispatcher: ${agents.length} agents (${agents.join(', ')})`);
        } catch (err: any) {
            this.logger.error(`Registration failed: ${err.message}`);
        }
    }

    private async loadAgentIds(): Promise<string[]> {
        try {
            const apiKey = this.config.get<string>('PLATFORM_API_KEY');
            if (!apiKey) return [];

            const data = await this.platform.queryWithAuth<any>(
                `{ agents(first: 50) { edges { node { ozonetelAgentId } } } }`,
                undefined,
                `Bearer ${apiKey}`,
            );

            return (data.agents?.edges ?? [])
                .map((e: any) => e.node.ozonetelAgentId)
                .filter((id: string) => id && id !== 'PENDING');
        } catch (err: any) {
            this.logger.warn(`Failed to load agents from platform: ${err.message}`);
            return [];
        }
    }
}