package daemon

import (
	"context"
	"fmt"
	"log/slog"
	"strings"
	"sync"

	"banger/internal/imagecat"
	"banger/internal/imagepull"
	"banger/internal/model"
	"banger/internal/paths"
	"banger/internal/store"
	"banger/internal/system"
)

// ImageService owns everything image-registry-related: register /
// promote / delete / pull (bundle + OCI), plus the kernel catalog
// operations that share the same lifecycle primitives. The publication
// lock imageOpsMu lives here so its scope is obvious at the field
// definition, and the three OCI-pull test seams (pullAndFlatten,
// finalizePulledRootfs, bundleFetch) are fields on the service rather
// than mutable globals on Daemon.
//
// Kept unexported except where peer services (VMService) need it, and
// peer access goes through consumer-defined interfaces, not direct
// struct poking.
type ImageService struct {
	runner system.CommandRunner
	logger *slog.Logger
	config model.DaemonConfig
	layout paths.Layout
	store  *store.Store

	// imageOpsMu is the publication-window lock: held only across the
	// "recheck name free + atomic rename + UpsertImage" commit. See
	// internal/daemon/ARCHITECTURE.md.
	imageOpsMu sync.Mutex

	// Test seams; nil → real implementation.
	pullAndFlatten       func(ctx context.Context, ref, cacheDir, destDir string) (imagepull.Metadata, error)
	finalizePulledRootfs func(ctx context.Context, ext4File string, meta imagepull.Metadata) error
	bundleFetch          func(ctx context.Context, destDir string, entry imagecat.CatEntry) (imagecat.Manifest, error)

	// beginOperation is a test seam used by a couple of image ops that
	// want structured operation logging. Nil → Daemon's beginOperation,
	// injected at construction.
	beginOperation func(name string, attrs ...any) *operationLog
}

// imageServiceDeps names every handle ImageService needs from the
// Daemon composition root. Using a struct (rather than positional args)
// makes the wiring site in Daemon.Open read as a declaration.
type imageServiceDeps struct {
	runner         system.CommandRunner
	logger         *slog.Logger
	config         model.DaemonConfig
	layout         paths.Layout
	store          *store.Store
	beginOperation func(name string, attrs ...any) *operationLog
}

func newImageService(deps imageServiceDeps) *ImageService {
	return &ImageService{
		runner:         deps.runner,
		logger:         deps.logger,
		config:         deps.config,
		layout:         deps.layout,
		store:          deps.store,
		beginOperation: deps.beginOperation,
	}
}

// FindImage is the service-owned lookup helper. It falls back from
// exact-name → exact-id → prefix match, matching the historical
// daemon.FindImage behaviour. Kept on ImageService because image
// lookup is inherently a service concern.
func (s *ImageService) FindImage(ctx context.Context, idOrName string) (model.Image, error) {
	if idOrName == "" {
		return model.Image{}, fmt.Errorf("image id or name is required")
	}
	if image, err := s.store.GetImageByName(ctx, idOrName); err == nil {
		return image, nil
	}
	if image, err := s.store.GetImageByID(ctx, idOrName); err == nil {
		return image, nil
	}
	images, err := s.store.ListImages(ctx)
	if err != nil {
		return model.Image{}, err
	}
	matchCount := 0
	var match model.Image
	for _, image := range images {
		if strings.HasPrefix(image.ID, idOrName) || strings.HasPrefix(image.Name, idOrName) {
			match = image
			matchCount++
		}
	}
	if matchCount == 1 {
		return match, nil
	}
	if matchCount > 1 {
		return model.Image{}, fmt.Errorf("multiple images match %q", idOrName)
	}
	return model.Image{}, fmt.Errorf("image %q not found", idOrName)
}