package tavily

import (
	"bytes"
	"encoding/json"
	"fmt"
	"net/http"
	"time"
)

const (
	baseURL    = "https://api.tavily.com"
	searchPath = "/search"
	timeout    = 30 * time.Second
)

// Client calls Tavily Search API.
type Client struct {
	APIKey     string
	HTTPClient *http.Client
}

// NewClient creates a Tavily client. apiKey is required for search.
func NewClient(apiKey string) *Client {
	return &Client{
		APIKey: apiKey,
		HTTPClient: &http.Client{
			Timeout: timeout,
		},
	}
}

// SearchRequest is the POST body for /search.
type SearchRequest struct {
	Query       string `json:"query"`
	SearchDepth string `json:"search_depth,omitempty"` // basic, advanced, etc.
	MaxResults  int    `json:"max_results,omitempty"`
}

// SearchResult is one result item.
type SearchResult struct {
	Title   string `json:"title"`
	URL     string `json:"url"`
	Content string `json:"content"`
}

// SearchResponse is the Tavily search response.
type SearchResponse struct {
	Query   string         `json:"query"`
	Answer  string         `json:"answer,omitempty"`
	Results []SearchResult `json:"results"`
}

// Search runs a web search and returns a single text suitable for passing to Ollama as tool result.
func (c *Client) Search(query string) (string, error) {
	if c.APIKey == "" {
		return "", fmt.Errorf("tavily: API key not set")
	}
	body, err := json.Marshal(SearchRequest{
		Query:      query,
		MaxResults: 5,
	})
	if err != nil {
		return "", fmt.Errorf("marshal request: %w", err)
	}

	url := baseURL + searchPath
	req, err := http.NewRequest(http.MethodPost, url, bytes.NewReader(body))
	if err != nil {
		return "", fmt.Errorf("new request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "Bearer "+c.APIKey)

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

	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("tavily returned %d", resp.StatusCode)
	}

	var out SearchResponse
	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
		return "", fmt.Errorf("decode response: %w", err)
	}

	// Build a single text for the model: prefer answer if present, else concatenate results.
	if out.Answer != "" {
		return out.Answer, nil
	}
	var b bytes.Buffer
	for i, r := range out.Results {
		if i > 0 {
			b.WriteString("\n\n")
		}
		b.WriteString(r.Title)
		b.WriteString(": ")
		b.WriteString(r.Content)
	}
	return b.String(), nil
}