package ai

import (
	"context"
	"fmt"

	"gitea.oblak.solutions/dimitar/gitFlow/internal/config"
	"gitea.oblak.solutions/dimitar/gitFlow/internal/httpclient"
	"gitea.oblak.solutions/dimitar/gitFlow/pkg/status"
)

const defaultOpenAIBaseURL = "https://api.openai.com/v1"

// OpenAIProvider talks to the OpenAI Chat Completions API.
type OpenAIProvider struct {
	model   string
	baseURL string
	apiKey  string
	http    *httpclient.Client
}

// NewOpenAI builds an OpenAI provider. base_url and model fall back to
// sensible defaults when unset in the configuration.
func NewOpenAI(cfg config.AIConfig, apiKey string) *OpenAIProvider {
	baseURL := cfg.BaseURL
	if baseURL == "" {
		baseURL = defaultOpenAIBaseURL
	}
	model := cfg.Model
	if model == "" {
		model = "gpt-4o"
	}
	return &OpenAIProvider{model: model, baseURL: baseURL, apiKey: apiKey, http: httpclient.New()}
}

// Name implements Provider.
func (p *OpenAIProvider) Name() string { return "openai" }

// chatMessage is a single chat turn, shared with the other providers.
type chatMessage struct {
	Role    string `json:"role"`
	Content string `json:"content"`
}

type chatRequest struct {
	Model          string          `json:"model"`
	Messages       []chatMessage   `json:"messages"`
	ResponseFormat *responseFormat `json:"response_format,omitempty"`
}

type responseFormat struct {
	Type string `json:"type"` // "json_object"
}

type chatResponse struct {
	Choices []struct {
		Message chatMessage `json:"message"`
	} `json:"choices"`
	Error *struct {
		Message string `json:"message"`
	} `json:"error"`
}

// Suggest implements Provider.
func (p *OpenAIProvider) Suggest(ctx context.Context, result status.ScanResult) ([]Suggestion, error) {
	req := chatRequest{
		Model: p.model,
		Messages: []chatMessage{
			{Role: "system", Content: "You are gitflow, a concise Git repository health assistant. You reply with JSON only."},
			{Role: "user", Content: BuildPrompt(result)},
		},
		ResponseFormat: &responseFormat{Type: "json_object"},
	}

	var resp chatResponse
	err := p.http.PostJSON(ctx, p.baseURL+"/chat/completions",
		map[string]string{"Authorization": "Bearer " + p.apiKey}, req, &resp)
	if err != nil {
		return nil, err
	}
	if resp.Error != nil {
		return nil, fmt.Errorf("ai: openai: %s", resp.Error.Message)
	}
	if len(resp.Choices) == 0 {
		return nil, fmt.Errorf("ai: openai: empty response")
	}
	return parseSuggestions(resp.Choices[0].Message.Content)
}