package api

import (
	"log/slog"
	"net/http"
)

// pruneImages handles POST /api/docker/prune-images.
// Only removes images that belong to Docker Watcher projects (not all system images).
func (s *Server) pruneImages(w http.ResponseWriter, r *http.Request) {
	if s.docker == nil {
		respondError(w, http.StatusServiceUnavailable, "Docker is not available")
		return
	}

	// Collect all image references from our projects.
	projects, err := s.store.GetAllProjects()
	if err != nil {
		slog.Error("prune: failed to list projects", "error", err)
		respondError(w, http.StatusInternalServerError, "internal server error")
		return
	}

	// Build a set of image refs used by active instances.
	activeImages := make(map[string]bool)
	for _, p := range projects {
		stages, _ := s.store.GetStagesByProjectID(p.ID)
		for _, st := range stages {
			instances, _ := s.store.GetInstancesByStageID(st.ID)
			for _, inst := range instances {
				if inst.ImageTag != "" {
					activeImages[p.Image+":"+inst.ImageTag] = true
				}
			}
		}
	}

	// Collect all unique image bases from projects (without tags).
	projectImages := make(map[string]bool)
	for _, p := range projects {
		if p.Image != "" {
			projectImages[p.Image] = true
		}
	}

	if len(projectImages) == 0 {
		respondJSON(w, http.StatusOK, map[string]any{
			"images_removed":     0,
			"space_reclaimed_mb": 0,
			"message":            "No project images to clean up",
		})
		return
	}

	// List all local Docker images and find ones matching our projects but not actively used.
	ctx := r.Context()
	removed := 0
	var reclaimedBytes int64

	for imageBase := range projectImages {
		// List all tags for this image.
		images, err := s.docker.ListImagesByRef(ctx, imageBase)
		if err != nil {
			slog.Warn("prune: list images", "image", imageBase, "error", err)
			continue
		}

		for _, img := range images {
			// Skip images that are actively used by running instances.
			if activeImages[img.Ref] {
				continue
			}

			// Remove unused image.
			if err := s.docker.RemoveImage(ctx, img.ID); err != nil {
				slog.Warn("prune: remove image", "image", img.Ref, "error", err)
				continue
			}
			removed++
			reclaimedBytes += img.Size
			slog.Info("prune: removed image", "ref", img.Ref, "size_mb", img.Size/(1024*1024))
		}
	}

	respondJSON(w, http.StatusOK, map[string]any{
		"images_removed":     removed,
		"space_reclaimed_mb": reclaimedBytes / (1024 * 1024),
	})
}