package resolver

import (
	"fmt"
	"log"
	"sync"
)

var (
	globalResolver *FastResolver
	resolverOnce   sync.Once
	resolverErr    error
)

// GetResolver returns a process-wide singleton FastResolver instance.
// Package index loading (and thus Sources.xz parsing) will happen at most once per process.
func GetResolver(cacheDir, mirror, suite, component string) (*FastResolver, error) {
	resolverOnce.Do(func() {
		log.Println("[resolver] Initializing global resolver (loading package index)")

		r := NewFastResolver(cacheDir)

		if err := r.LoadIndex(mirror, suite, component); err != nil {
			resolverErr = fmt.Errorf("failed to load package index: %w", err)
			return
		}

		globalResolver = r

		log.Println("[resolver] Global resolver initialized successfully")
	})

	if resolverErr != nil {
		return nil, resolverErr
	}

	if globalResolver == nil {
		return nil, fmt.Errorf("resolver initialization failed")
	}

	return globalResolver, nil
}

// GetGlobalResolver is kept for backward compatibility.
// New code should use GetResolver instead.
func GetGlobalResolver(cacheDir, mirror, suite, component string) (*FastResolver, error) {
	return GetResolver(cacheDir, mirror, suite, component)
}