package llm

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

	"github.com/paramah/ai_devs4/s01e01/internal/domain"
)

// LMStudioProvider implements domain.LLMProvider for local LM Studio
type LMStudioProvider struct {
	baseURL string
	model   string
	client  *http.Client
}

// NewLMStudioProvider creates a new LM Studio provider
func NewLMStudioProvider(baseURL, model string) *LMStudioProvider {
	return &LMStudioProvider{
		baseURL: baseURL,
		model:   model,
		client:  &http.Client{},
	}
}

type lmStudioRequest struct {
	Model          string                   `json:"model"`
	Messages       []map[string]interface{} `json:"messages"`
	ResponseFormat *lmResponseFormat        `json:"response_format,omitempty"`
	Temperature    float64                  `json:"temperature,omitempty"`
}

type lmResponseFormat struct {
	Type       string      `json:"type"`
	JSONSchema interface{} `json:"json_schema,omitempty"`
}

type lmStudioResponse struct {
	Choices []struct {
		Message struct {
			Content string `json:"content"`
		} `json:"message"`
	} `json:"choices"`
	Error json.RawMessage `json:"error,omitempty"`
}

// Complete sends a request to LM Studio local server
func (p *LMStudioProvider) Complete(ctx context.Context, request domain.LLMRequest) (*domain.LLMResponse, error) {
	reqBody := lmStudioRequest{
		Model: p.model,
		Messages: []map[string]interface{}{
			{
				"role":    "user",
				"content": request.Prompt,
			},
		},
		Temperature: 0.7,
	}

	if request.Schema != nil {
		reqBody.ResponseFormat = &lmResponseFormat{
			Type:       "json_schema",
			JSONSchema: request.Schema,
		}
	}

	jsonData, err := json.Marshal(reqBody)
	if err != nil {
		return nil, fmt.Errorf("marshaling request: %w", err)
	}

	url := p.baseURL + "/v1/chat/completions"
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewBuffer(jsonData))
	if err != nil {
		return nil, fmt.Errorf("creating request: %w", err)
	}

	req.Header.Set("Content-Type", "application/json")

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

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

	// Check HTTP status
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("HTTP %d: %s", resp.StatusCode, string(body))
	}

	var apiResp lmStudioResponse
	if err := json.Unmarshal(body, &apiResp); err != nil {
		return nil, fmt.Errorf("unmarshaling response: %w\nResponse body: %s", err, string(body))
	}

	// Check for error in response
	if len(apiResp.Error) > 0 {
		// Try to parse as string
		var errStr string
		if err := json.Unmarshal(apiResp.Error, &errStr); err == nil {
			return nil, fmt.Errorf("API error: %s", errStr)
		}
		// Try to parse as object with message field
		var errObj struct {
			Message string `json:"message"`
		}
		if err := json.Unmarshal(apiResp.Error, &errObj); err == nil {
			return nil, fmt.Errorf("API error: %s", errObj.Message)
		}
		// Fallback to raw error
		return nil, fmt.Errorf("API error: %s", string(apiResp.Error))
	}

	if len(apiResp.Choices) == 0 {
		return nil, fmt.Errorf("no choices in response. Response body: %s", string(body))
	}

	return &domain.LLMResponse{
		Content: apiResp.Choices[0].Message.Content,
	}, nil
}