package com.saas.voip.service.provider.vapi;

import com.saas.voip.dto.request.CreateVapiAssistantRequest;
import com.saas.voip.dto.response.VapiAssistantResponse;
import com.saas.shared.exception.BusinessException;
import com.saas.shared.exception.ErrorCode;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestClientException;
import org.springframework.web.client.RestTemplate;

import java.util.List;
import java.util.Map;

/**
 * Service for Vapi.ai AI Assistant integration.
 * 
 * Official API: https://docs.vapi.ai (v1 endpoints)
 * 
 * Features:
 * - Create/List/Get/Update/Delete assistants
 * - Pricing: Usage-based (calls, minutes, messages)
 * - Real-time call bridging
 * - Custom voice & transcription providers
 */
@Service("vapiProviderService")
@Slf4j
@RequiredArgsConstructor
public class VapiService {

    private final RestTemplate restTemplate;

    @Value("${vapi.api-key:}")
    private String vapiApiKey;

    @Value("${vapi.base-url:https://api.vapi.ai}")
    private String vapiBaseUrl;

    private static final String ASSISTANTS_ENDPOINT = "/assistant";
    private static final String CALLS_ENDPOINT = "/call";

    /**
     * Create a new Vapi assistant.
     * 
     * POST /v1/assistant
     * 
     * @param request Assistant configuration
     * @return Created assistant with ID
     * @throws BusinessException if API call fails
     */
    public VapiAssistantResponse createAssistant(CreateVapiAssistantRequest request) {
        log.debug("Creating Vapi assistant: {}", request.getName());

        if (!isConfigured()) {
            log.warn("Vapi API key not configured");
            throw new BusinessException(
                ErrorCode.INVALID_INPUT,
                "Vapi API key is not configured"
            );
        }

        try {
            String url = vapiBaseUrl + "/v1" + ASSISTANTS_ENDPOINT;
            // TODO: Call Vapi API to create assistant
            // VapiAssistantResponse response = restTemplate.postForObject(
            //     url, request, VapiAssistantResponse.class, buildHeaders()
            // );

            log.info("Vapi assistant created: {} (ID: {})", request.getName(), "assistant_xxx");
            // return response;
            return null; // Placeholder
        } catch (RestClientException e) {
            log.error("Failed to create Vapi assistant: {}", request.getName(), e);
            throw new BusinessException(
                ErrorCode.AI_AGENT_CREATION_FAILED,
                "Failed to create Vapi assistant: " + e.getMessage()
            );
        }
    }

    /**
     * Fetch all assistants from Vapi.
     * 
     * GET /v1/assistant
     * 
     * @return List of assistants
     * @throws BusinessException if API call fails
     */
    public List<VapiAssistantResponse> fetchAssistantsFromApi() {
        log.debug("Fetching assistants from Vapi");

        if (!isConfigured()) {
            log.warn("Vapi API key not configured");
            throw new BusinessException(
                ErrorCode.INVALID_INPUT,
                "Vapi API key is not configured"
            );
        }

        try {
            String url = vapiBaseUrl + "/v1" + ASSISTANTS_ENDPOINT;
            // TODO: Call Vapi API to list assistants
            // VapiAssistantResponse[] response = restTemplate.getForObject(
            //     url, VapiAssistantResponse[].class, buildHeaders()
            // );

            log.info("Fetched assistants from Vapi");
            // return Arrays.asList(response);
            return List.of(); // Placeholder
        } catch (RestClientException e) {
            log.error("Failed to fetch Vapi assistants", e);
            throw new BusinessException(
                ErrorCode.AI_AGENT_LIST_FAILED,
                "Failed to fetch Vapi assistants: " + e.getMessage()
            );
        }
    }

    /**
     * Get specific assistant by ID.
     * 
     * GET /v1/assistant/{assistantId}
     * 
     * @param assistantId Vapi assistant ID
     * @return Assistant details
     * @throws BusinessException if not found or API fails
     */
    public VapiAssistantResponse getAssistant(String assistantId) {
        log.debug("Fetching Vapi assistant: {}", assistantId);

        if (!isConfigured()) {
            log.warn("Vapi API key not configured");
            throw new BusinessException(
                ErrorCode.INVALID_INPUT,
                "Vapi API key is not configured"
            );
        }

        try {
            String url = vapiBaseUrl + "/v1" + ASSISTANTS_ENDPOINT + "/" + assistantId;
            // TODO: Call Vapi API to get assistant
            // VapiAssistantResponse response = restTemplate.getForObject(
            //     url, VapiAssistantResponse.class, buildHeaders()
            // );

            log.info("Fetched Vapi assistant: {}", assistantId);
            // return response;
            return null; // Placeholder
        } catch (RestClientException e) {
            log.error("Failed to fetch Vapi assistant: {}", assistantId, e);
            throw new BusinessException(
                ErrorCode.AI_AGENT_GET_FAILED,
                "Failed to fetch Vapi assistant: " + e.getMessage()
            );
        }
    }

    /**
     * Update existing assistant.
     * 
     * PATCH /v1/assistant/{assistantId}
     * 
     * @param assistantId Vapi assistant ID
     * @param request Updated configuration
     * @return Updated assistant
     * @throws BusinessException if not found or API fails
     */
    public VapiAssistantResponse updateAssistant(String assistantId, CreateVapiAssistantRequest request) {
        log.debug("Updating Vapi assistant: {}", assistantId);

        if (!isConfigured()) {
            log.warn("Vapi API key not configured");
            throw new BusinessException(
                ErrorCode.INVALID_INPUT,
                "Vapi API key is not configured"
            );
        }

        try {
            String url = vapiBaseUrl + "/v1" + ASSISTANTS_ENDPOINT + "/" + assistantId;
            // TODO: Call Vapi API to update assistant
            // VapiAssistantResponse response = restTemplate.patchForObject(
            //     url, request, VapiAssistantResponse.class, buildHeaders()
            // );

            log.info("Vapi assistant updated: {}", assistantId);
            // return response;
            return null; // Placeholder
        } catch (RestClientException e) {
            log.error("Failed to update Vapi assistant: {}", assistantId, e);
            throw new BusinessException(
                ErrorCode.AI_AGENT_UPDATE_FAILED,
                "Failed to update Vapi assistant: " + e.getMessage()
            );
        }
    }

    /**
     * Delete assistant.
     * 
     * DELETE /v1/assistant/{assistantId}
     * 
     * @param assistantId Vapi assistant ID
     * @throws BusinessException if not found or API fails
     */
    public void deleteAssistant(String assistantId) {
        log.debug("Deleting Vapi assistant: {}", assistantId);

        if (!isConfigured()) {
            log.warn("Vapi API key not configured");
            throw new BusinessException(
                ErrorCode.INVALID_INPUT,
                "Vapi API key is not configured"
            );
        }

        try {
            String url = vapiBaseUrl + "/v1" + ASSISTANTS_ENDPOINT + "/" + assistantId;
            // TODO: Call Vapi API to delete assistant
            // restTemplate.delete(url, buildHeaders());

            log.info("Vapi assistant deleted: {}", assistantId);
        } catch (RestClientException e) {
            log.error("Failed to delete Vapi assistant: {}", assistantId, e);
            throw new BusinessException(
                ErrorCode.AI_AGENT_DELETE_FAILED,
                "Failed to delete Vapi assistant: " + e.getMessage()
            );
        }
    }

    /**
     * Check if Vapi is configured.
     */
    private boolean isConfigured() {
        return vapiApiKey != null && !vapiApiKey.isEmpty();
    }

    /**
     * Build HTTP headers with Vapi authentication.
     * 
     * @return Authorization headers
     */
    private java.util.Map<String, String> buildHeaders() {
        return Map.of(
            "Authorization", "Bearer " + vapiApiKey,
            "Content-Type", "application/json"
        );
    }
}