// Package research provides the SearXNG HTTP search client and the ResearchAgent
// background worker that enriches needs_research hardware records.
package research

import (
	"context"
	"fmt"
	"net/http"
	"net/url"
	"time"

	"encoding/json"

	"git.georgsen.dk/hwlab/internal/ai"
)

const defaultSearXNGURL = "http://10.5.0.129:8080"

// searxngResponse is the parsed JSON body returned by SearXNG.
// SearXNG uses "content" for the text snippet, not "snippet".
type searxngResponse struct {
	Results []searxngResult `json:"results"`
}

type searxngResult struct {
	Title   string `json:"title"`
	URL     string `json:"url"`
	Content string `json:"content"`
}

// SearXNGClient implements ai.ResearchClient using a self-hosted SearXNG instance.
type SearXNGClient struct {
	baseURL    string
	httpClient *http.Client
}

// NewSearXNGClient creates a SearXNGClient. If baseURL is empty the default LAN
// address (http://10.5.0.129:8080) is used.
func NewSearXNGClient(baseURL string) *SearXNGClient {
	if baseURL == "" {
		baseURL = defaultSearXNGURL
	}
	return &SearXNGClient{
		baseURL: baseURL,
		httpClient: &http.Client{
			Timeout: 15 * time.Second,
		},
	}
}

// Search executes a GET {baseURL}/search?q={query}&format=json and returns parsed results.
// An HTTP non-2xx response is returned as an error. An empty results array is not an error.
func (c *SearXNGClient) Search(ctx context.Context, query string) ([]ai.SearchResult, error) {
	params := url.Values{}
	params.Set("q", query)
	params.Set("format", "json")
	reqURL := c.baseURL + "/search?" + params.Encode()

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, reqURL, nil)
	if err != nil {
		return nil, fmt.Errorf("searxng: build request: %w", err)
	}

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("searxng: http get: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return nil, fmt.Errorf("searxng: unexpected status %d", resp.StatusCode)
	}

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

	results := make([]ai.SearchResult, 0, len(body.Results))
	for _, r := range body.Results {
		results = append(results, ai.SearchResult{
			Title:   r.Title,
			URL:     r.URL,
			Snippet: r.Content,
		})
	}
	return results, nil
}