package speech

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	"time"
)

const whisperAPIURL = "https://api.openai.com/v1/audio/transcriptions"

type OpenAIWhisper struct {
	apiKey   string
	model    string
	language string
	client   *http.Client
}

func NewOpenAIWhisper(apiKey, model, language string) *OpenAIWhisper {
	return &OpenAIWhisper{
		apiKey:   apiKey,
		model:    model,
		language: language,
		client:   &http.Client{Timeout: 60 * time.Second},
	}
}

type whisperResponse struct {
	Text string `json:"text"`
}

func (w *OpenAIWhisper) Transcribe(ctx context.Context, audioData []byte, mimeType string) (string, error) {
	var buf bytes.Buffer
	mw := multipart.NewWriter(&buf)

	fw, err := mw.CreateFormFile("file", "audio.wav")
	if err != nil {
		return "", fmt.Errorf("create form file: %w", err)
	}
	if _, err := fw.Write(audioData); err != nil {
		return "", fmt.Errorf("write audio data: %w", err)
	}

	if err := mw.WriteField("model", w.model); err != nil {
		return "", fmt.Errorf("write model field: %w", err)
	}
	if err := mw.WriteField("response_format", "json"); err != nil {
		return "", fmt.Errorf("write response_format: %w", err)
	}
	if w.language != "" {
		if err := mw.WriteField("language", w.language); err != nil {
			return "", fmt.Errorf("write language field: %w", err)
		}
	}
	mw.Close()

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, whisperAPIURL, &buf)
	if err != nil {
		return "", fmt.Errorf("create whisper request: %w", err)
	}
	req.Header.Set("Authorization", "Bearer "+w.apiKey)
	req.Header.Set("Content-Type", mw.FormDataContentType())

	resp, err := w.client.Do(req)
	if err != nil {
		return "", fmt.Errorf("whisper API call: %w", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return "", fmt.Errorf("read whisper response: %w", err)
	}

	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("whisper API error %d: %s", resp.StatusCode, string(body))
	}

	var result whisperResponse
	if err := json.Unmarshal(body, &result); err != nil {
		return "", fmt.Errorf("parse whisper response: %w", err)
	}

	return result.Text, nil
}