package web

import (
	"net/http"
	"strings"

	"music-server/internal/backend"
	"music-server/internal/logging"

	"go.uber.org/zap"
)

// NewSearchHandler returns a handler that renders the soundtracks matching the posted search term.
func NewSearchHandler(cache *backend.SearchCache) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if err := r.ParseForm(); err != nil {
			http.Error(w, "Bad Request", http.StatusBadRequest)
			return
		}

		soundtracks, err := cache.Get(r.Context())
		if err != nil {
			logging.GetLogger().Error("Failed to load search data", zap.Error(err))
			http.Error(w, "Internal Server Error", http.StatusInternalServerError)
			return
		}

		results := search(r.FormValue("search_term"), soundtracks)
		if err := FoundSoundtracks(results).Render(r.Context(), w); err != nil {
			logging.GetLogger().Error("Failed to render search results", zap.Error(err))
			http.Error(w, "Internal Server Error", http.StatusInternalServerError)
		}
	})
}

// search returns the soundtracks matching searchText: exact matches first, then matches
// ignoring spaces and special characters, then matches with the letters in order.
func search(searchText string, soundtrackData []backend.SoundtrackData) []string {
	var results []string
	seen := make(map[string]bool)
	add := func(match func(backend.SoundtrackData) bool) {
		for _, data := range soundtrackData {
			if !seen[data.Original] && match(data) {
				results = append(results, data.Original)
				seen[data.Original] = true
			}
		}
	}

	lowercase := strings.ToLower(searchText)
	cleaned := backend.CleanSearchTerm(searchText)

	add(func(d backend.SoundtrackData) bool { return strings.Contains(d.Lowercase, lowercase) })
	add(func(d backend.SoundtrackData) bool { return strings.Contains(d.Cleaned, cleaned) })
	add(func(d backend.SoundtrackData) bool { return backend.MatchesSubsequence(cleaned, d.Cleaned) })
	return results
}