Search/images.go

package main

import (
	"fmt"
	"html/template"
	"log"
	"math/rand"
	"net/http"
	"sync"
	"time"
)

var (
	imageEngines    []imageEngine
	imageEngineLock sync.Mutex
)

type imageEngine struct {
	Name   string
	Func   func(string, string, string, int) ([]ImageSearchResult, error)
	Weight int
}

func init() {
	imageEngines = []imageEngine{
		{Name: "Qwant", Func: PerformQwantImageSearch, Weight: 1},
		{Name: "Imgur", Func: PerformImgurImageSearch, Weight: 2},
	}

	rand.Seed(time.Now().UnixNano())
}

func handleImageSearch(w http.ResponseWriter, query, safe, lang string, page int) {
	startTime := time.Now()

	cacheKey := CacheKey{Query: query, Page: page, Safe: safe == "true", Lang: lang, Type: "image"}
	combinedResults := getImageResultsFromCacheOrFetch(cacheKey, query, safe, lang, page)

	elapsedTime := time.Since(startTime)
	tmpl, err := template.New("images.html").Funcs(funcs).ParseFiles("templates/images.html")
	if err != nil {
		log.Printf("Error parsing template: %v", err)
		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
		return
	}

	data := struct {
		Results         []ImageSearchResult
		Query           string
		Page            int
		Fetched         string
		LanguageOptions []LanguageOption
		CurrentLang     string
		HasPrevPage     bool
		HasNextPage     bool
	}{
		Results:         combinedResults,
		Query:           query,
		Page:            page,
		Fetched:         fmt.Sprintf("%.2f seconds", elapsedTime.Seconds()),
		LanguageOptions: languageOptions,
		CurrentLang:     lang,
		HasPrevPage:     page > 1,
		HasNextPage:     len(combinedResults) >= 50,
	}

	err = tmpl.Execute(w, data)
	if err != nil {
		log.Printf("Error executing template: %v", err)
		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
	}
}

func getImageResultsFromCacheOrFetch(cacheKey CacheKey, query, safe, lang string, page int) []ImageSearchResult {
	cacheChan := make(chan []SearchResult)
	var combinedResults []ImageSearchResult

	go func() {
		results, exists := resultsCache.Get(cacheKey)
		if exists {
			log.Println("Cache hit")
			cacheChan <- results
		} else {
			log.Println("Cache miss")
			cacheChan <- nil
		}
	}()

	select {
	case results := <-cacheChan:
		if results == nil {
			combinedResults = fetchImageResults(query, safe, lang, page)
			if len(combinedResults) > 0 {
				resultsCache.Set(cacheKey, convertToSearchResults(combinedResults))
			}
		} else {
			_, _, imageResults := convertToSpecificResults(results)
			combinedResults = imageResults
		}
	case <-time.After(2 * time.Second):
		log.Println("Cache check timeout")
		combinedResults = fetchImageResults(query, safe, lang, page)
		if len(combinedResults) > 0 {
			resultsCache.Set(cacheKey, convertToSearchResults(combinedResults))
		}
	}

	return combinedResults
}

func fetchImageResults(query, safe, lang string, page int) []ImageSearchResult {
	var results []ImageSearchResult
	var err error

	for attempts := 0; attempts < len(imageEngines); attempts++ {
		engine := selectImageEngine()
		log.Printf("Using image search engine: %s", engine.Name)

		results, err = engine.Func(query, safe, lang, page)
		if err != nil {
			log.Printf("Error performing image search with %s: %v", engine.Name, err)
			continue
		}

		if len(results) > 0 {
			break
		}
	}

	return results
}

func selectImageEngine() imageEngine {
	imageEngineLock.Lock()
	defer imageEngineLock.Unlock()

	totalWeight := 0
	for _, engine := range imageEngines {
		totalWeight += engine.Weight
	}

	randValue := rand.Intn(totalWeight)
	for _, engine := range imageEngines {
		if randValue < engine.Weight {
			// Adjust weights for load balancing
			for i := range imageEngines {
				if imageEngines[i].Name == engine.Name {
					imageEngines[i].Weight = max(1, imageEngines[i].Weight-1)
				} else {
					imageEngines[i].Weight++
				}
			}
			return engine
		}
		randValue -= engine.Weight
	}

	return imageEngines[0] // fallback to the first engine
}