package ai_summarizer

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	"tm/pkg/logger"
)

// Client is the HTTP client for the AI summarization on-demand API.
type Client struct {
	config     *Config
	httpClient *http.Client
	logger     logger.Logger
}

// NewClient creates a new AI summarizer HTTP client.
func NewClient(config *Config, log logger.Logger) (*Client, error) {
	if config == nil {
		config = DefaultConfig()
	}
	if err := config.ValidateAPI(); err != nil {
		return nil, fmt.Errorf("ai_summarizer: invalid config: %w", err)
	}

	return &Client{
		config: config,
		httpClient: &http.Client{
			Timeout: config.APITimeout,
		},
		logger: log,
	}, nil
}

// FetchSummaryOnDemand calls the external AI service POST /ai/summarize endpoint
// to generate a summary on demand. It retries on transient failures up to the
// configured number of attempts.
func (c *Client) FetchSummaryOnDemand(ctx context.Context, reqBody SummarizeRequest) (*SummarizeResponse, error) {
	jsonBody, err := json.Marshal(reqBody)
	if err != nil {
		return nil, fmt.Errorf("ai_summarizer: failed to marshal request body: %w", err)
	}

	url := c.config.APIBaseURL + "/ai/summarize"

	var lastErr error
	for attempt := 0; attempt <= c.config.APIRetryCount; attempt++ {
		if attempt > 0 {
			c.logger.Warn("Retrying AI summarize request", map[string]interface{}{
				"contract_folder_id":    reqBody.ContractFolderID,
				"notice_publication_id": reqBody.NoticePublicationID,
				"attempt":               attempt,
			})
			select {
			case <-ctx.Done():
				return nil, ctx.Err()
			case <-time.After(c.config.APIRetryDelay):
			}
		}

		resp, err := c.doPost(ctx, url, jsonBody)
		if err != nil {
			lastErr = err
			c.logger.Error("AI summarize request failed", map[string]interface{}{
				"contract_folder_id":    reqBody.ContractFolderID,
				"notice_publication_id": reqBody.NoticePublicationID,
				"attempt":               attempt,
				"error":                 err.Error(),
			})
			continue
		}

		return resp, nil
	}

	return nil, fmt.Errorf("ai_summarizer: all %d attempts failed, last error: %w", c.config.APIRetryCount+1, lastErr)
}

// FetchTranslationOnDemand calls the external AI service POST /ai/translate endpoint
// to generate title/description translation on demand.
func (c *Client) FetchTranslationOnDemand(ctx context.Context, reqBody TranslateRequest) (*TranslateResponse, error) {
	jsonBody, err := json.Marshal(reqBody)
	if err != nil {
		return nil, fmt.Errorf("ai_summarizer: failed to marshal translation request body: %w", err)
	}

	url := c.config.APIBaseURL + "/ai/translate"

	var lastErr error
	for attempt := 0; attempt <= c.config.APIRetryCount; attempt++ {
		if attempt > 0 {
			c.logger.Warn("Retrying AI translate request", map[string]interface{}{
				"notice_publication_id": reqBody.NoticePublicationID,
				"language":              reqBody.Language,
				"attempt":               attempt,
			})
			select {
			case <-ctx.Done():
				return nil, ctx.Err()
			case <-time.After(c.config.APIRetryDelay):
			}
		}

		resp, err := c.doTranslatePost(ctx, url, jsonBody)
		if err != nil {
			lastErr = err
			c.logger.Error("AI translate request failed", map[string]interface{}{
				"notice_publication_id": reqBody.NoticePublicationID,
				"language":              reqBody.Language,
				"attempt":               attempt,
				"error":                 err.Error(),
			})
			continue
		}

		return resp, nil
	}

	return nil, fmt.Errorf("ai_summarizer: all %d translation attempts failed, last error: %w", c.config.APIRetryCount+1, lastErr)
}

// TriggerPipelineTranslate calls POST /pipeline/translate to enqueue batch translation
// for the given target languages.
func (c *Client) TriggerPipelineTranslate(ctx context.Context, languages []string) (*PipelineTranslateResponse, error) {
	reqBody := PipelineTranslateRequest{Languages: languages}
	jsonBody, err := json.Marshal(reqBody)
	if err != nil {
		return nil, fmt.Errorf("ai_summarizer: failed to marshal pipeline translate request: %w", err)
	}

	url := c.config.APIBaseURL + "/pipeline/translate"
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(jsonBody))
	if err != nil {
		return nil, fmt.Errorf("ai_summarizer: failed to create pipeline translate request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json")

	httpResp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("ai_summarizer: pipeline translate request error: %w", err)
	}
	defer httpResp.Body.Close()

	bodyBytes, err := io.ReadAll(httpResp.Body)
	if err != nil {
		return nil, fmt.Errorf("ai_summarizer: failed to read pipeline translate response: %w", err)
	}
	if httpResp.StatusCode >= 400 {
		return nil, fmt.Errorf("%w: status %d, body: %s", ErrAPINonSuccess, httpResp.StatusCode, string(bodyBytes))
	}

	var result PipelineTranslateResponse
	if err := json.Unmarshal(bodyBytes, &result); err != nil {
		return nil, fmt.Errorf("ai_summarizer: failed to decode pipeline translate response: %w", err)
	}

	c.logger.Info("Pipeline translate triggered", map[string]interface{}{
		"status":    result.Status,
		"languages": result.Languages,
	})

	return &result, nil
}

// doPost performs a single POST request and parses the response.
func (c *Client) doPost(ctx context.Context, url string, jsonBody []byte) (*SummarizeResponse, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(jsonBody))
	if err != nil {
		return nil, fmt.Errorf("ai_summarizer: failed to create request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json")

	c.logger.Debug("Sending AI summarize request", map[string]interface{}{
		"url": url,
	})

	httpResp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("ai_summarizer: request error: %w", err)
	}
	defer httpResp.Body.Close()

	bodyBytes, err := io.ReadAll(httpResp.Body)
	if err != nil {
		return nil, fmt.Errorf("ai_summarizer: failed to read response body: %w", err)
	}

	if httpResp.StatusCode == http.StatusNotFound {
		return nil, fmt.Errorf("%w: status 404, body: %s", ErrObjectNotFound, string(bodyBytes))
	}

	if httpResp.StatusCode >= 400 {
		return nil, fmt.Errorf("%w: status %d, body: %s", ErrAPINonSuccess, httpResp.StatusCode, string(bodyBytes))
	}

	var result SummarizeResponse
	if err := json.Unmarshal(bodyBytes, &result); err != nil {
		return nil, fmt.Errorf("ai_summarizer: failed to decode response JSON: %w", err)
	}

	c.logger.Info("AI summarize request succeeded", map[string]interface{}{
		"contract_folder_id":    result.ContractFolderID,
		"notice_publication_id": result.ResolvedNoticePublicationID(),
		"summaries_count":       len(result.Summaries),
	})

	return &result, nil
}

// doTranslatePost performs a single translation POST request and parses the response.
func (c *Client) doTranslatePost(ctx context.Context, url string, jsonBody []byte) (*TranslateResponse, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(jsonBody))
	if err != nil {
		return nil, fmt.Errorf("ai_summarizer: failed to create translation request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json")

	c.logger.Debug("Sending AI translate request", map[string]interface{}{
		"url": url,
	})

	httpResp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("ai_summarizer: translation request error: %w", err)
	}
	defer httpResp.Body.Close()

	bodyBytes, err := io.ReadAll(httpResp.Body)
	if err != nil {
		return nil, fmt.Errorf("ai_summarizer: failed to read translation response body: %w", err)
	}

	if httpResp.StatusCode >= 400 {
		return nil, fmt.Errorf("%w: status %d, body: %s", ErrAPINonSuccess, httpResp.StatusCode, string(bodyBytes))
	}

	result, err := decodeTranslateResponse(bodyBytes)
	if err != nil {
		return nil, err
	}

	c.logger.Info("AI translate request succeeded", map[string]interface{}{
		"notice_publication_id": result.NoticePublicationID,
		"language":              result.Language,
	})

	return result, nil
}

type translateAPIEnvelope struct {
	Success bool              `json:"success"`
	Message string            `json:"message"`
	Data    TranslateResponse `json:"data"`
}

func decodeTranslateResponse(bodyBytes []byte) (*TranslateResponse, error) {
	var envelope translateAPIEnvelope
	if err := json.Unmarshal(bodyBytes, &envelope); err == nil && envelope.Success && envelope.Data.Language != "" {
		return &envelope.Data, nil
	}

	var direct TranslateResponse
	if err := json.Unmarshal(bodyBytes, &direct); err != nil {
		return nil, fmt.Errorf("ai_summarizer: failed to decode translation response JSON: %w", err)
	}
	if strings.TrimSpace(direct.Language) == "" {
		return nil, fmt.Errorf("ai_summarizer: translation response missing language")
	}
	return &direct, nil
}
