/*
   Copyright The containerd Authors.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package image

import (
	"context"
	"errors"
	"fmt"
	"regexp"
	"strings"
	"time"

	containerd "github.com/containerd/containerd/v2/client"
	"github.com/containerd/containerd/v2/core/images"
	"github.com/containerd/log"

	"github.com/containerd/nerdctl/v2/pkg/api/types"
	"github.com/containerd/nerdctl/v2/pkg/containerdutil"
	"github.com/containerd/nerdctl/v2/pkg/imageinspector"
	"github.com/containerd/nerdctl/v2/pkg/inspecttypes/dockercompat"
	"github.com/containerd/nerdctl/v2/pkg/referenceutil"
)

func inspectIdentifier(ctx context.Context, client *containerd.Client, identifier string) ([]images.Image, string, string, error) {
	// Figure out what we have here - digest, tag, name
	parsedReference, err := referenceutil.Parse(identifier)
	if err != nil {
		return nil, "", "", err
	}
	digest := ""
	if parsedReference.Digest != "" {
		digest = parsedReference.Digest.String()
	}
	name := parsedReference.Name()
	tag := parsedReference.Tag

	// Initialize filters
	var filters []string
	// This will hold the final image list, if any
	var imageList []images.Image

	// No digest in the request? Then assume it is a name
	if digest == "" {
		filters = []string{fmt.Sprintf("name==%s:%s", name, tag)}
		// Query it
		imageList, err = client.ImageService().List(ctx, filters...)
		if err != nil {
			return nil, "", "", fmt.Errorf("containerd image service failed: %w", err)
		}
		// Nothing? Then it could be a short id (aka truncated digest) - we are going to use this
		if len(imageList) == 0 {
			digest = fmt.Sprintf("sha256:%s.*", regexp.QuoteMeta(strings.TrimPrefix(identifier, "sha256:")))
			name = ""
			tag = ""
		} else {
			// Otherwise, we found one by name. Get the digest from it.
			digest = imageList[0].Target.Digest.String()
		}
	}

	// At this point, we DO have a digest (or short id), so, that is what we are retrieving
	filters = []string{fmt.Sprintf("target.digest~=^%s$", digest)}
	imageList, err = client.ImageService().List(ctx, filters...)
	if err != nil {
		return nil, "", "", fmt.Errorf("containerd image service failed: %w", err)
	}

	// TODO: docker does allow retrieving images by Id, so implement as a last ditch effort (probably look-up the store)

	// Return the list we found, along with normalized name and tag
	return imageList, name, tag, nil
}

// Inspect prints detailed information of each image in `images`.
func Inspect(ctx context.Context, client *containerd.Client, identifiers []string, options types.ImageInspectOptions) ([]any, error) {
	// Set a timeout
	ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
	defer cancel()

	// Will hold the final answers
	var errs []error
	var entries []interface{}

	snapshotter := containerdutil.SnapshotService(client, options.GOptions.Snapshotter)
	// We have to query per provided identifier, as we need to post-process results for the case name + digest
	for _, identifier := range identifiers {
		candidateImageList, requestedName, requestedTag, err := inspectIdentifier(ctx, client, identifier)
		if err != nil {
			errs = append(errs, fmt.Errorf("%w: %s", err, identifier))
			continue
		}

		var validatedImage *dockercompat.Image
		var repoTags []string
		var repoDigests []string

		// Go through the candidates
		for _, candidateImage := range candidateImageList {
			// Inspect the image
			candidateNativeImage, err := imageinspector.Inspect(ctx, client, candidateImage, snapshotter)
			if err != nil {
				log.G(ctx).WithError(err).WithField("name", candidateImage.Name).Error("failure inspecting image")
				continue
			}

			// If native, we just add everything in there and that's it
			if options.Mode == "native" {
				entries = append(entries, candidateNativeImage)
				continue
			}

			// If dockercompat: does the candidate have a name? Get it if so
			parsedReference, err := referenceutil.Parse(candidateNativeImage.Image.Name)
			if err != nil {
				log.G(ctx).WithError(err).WithField("name", candidateNativeImage.Image.Name).Error("the found image has an unparsable name")
				continue
			}

			// If we were ALSO asked for a specific name on top of the digest, we need to make sure we keep only the image with that name
			if requestedName != "" {
				// If the candidate did not have a name, then we should ignore this one and continue
				if parsedReference.Name() == "" {
					continue
				}

				// Otherwise, the candidate has a name. If it is the one we want, store it and continue, otherwise, fall through
				candidateTag := parsedReference.Tag
				// If the name had a digest, an empty tag is not normalized to latest, so, account for that here
				if requestedTag == "" {
					requestedTag = "latest"
				}
				if parsedReference.Name() == requestedName && candidateTag == requestedTag {
					validatedImage, err = dockercompat.ImageFromNative(candidateNativeImage)
					if err != nil {
						log.G(ctx).WithError(err).WithField("name", candidateNativeImage.Image.Name).Error("could not get a docker compat version of the native image")
					}
					continue
				}
			} else if validatedImage == nil {
				// Alternatively, we got a request by digest only, so, if we do not know about it already, store it and continue
				validatedImage, err = dockercompat.ImageFromNative(candidateNativeImage)
				if err != nil {
					log.G(ctx).WithError(err).WithField("name", candidateNativeImage.Image.Name).Error("could not get a docker compat version of the native image")
				}
				continue
			}

			// Fallthrough cases:
			// - we got a request by digest, but we already had the image stored
			// - we got a request by name, and the name of the candidate did not match the requested name
			// Now, check if the candidate has a name - if it does, populate repoTags and repoDigests
			if parsedReference.Name() != "" {
				tag := parsedReference.Tag
				if tag == "" {
					tag = "latest"
				}
				repoTags = append(repoTags, fmt.Sprintf("%s:%s", parsedReference.FamiliarName(), tag))
				repoDigests = append(repoDigests, fmt.Sprintf("%s@%s", parsedReference.FamiliarName(), candidateImage.Target.Digest.String()))
			}
		}

		// Done iterating through candidates. Did we find anything that matches?
		if options.Mode == "dockercompat" {
			if validatedImage == nil {
				errs = append(errs, fmt.Errorf("no such image: %s", identifier))
				continue
			}
			// Then slap in the repoTags and repoDigests we found from the other candidates
			validatedImage.RepoTags = append(validatedImage.RepoTags, repoTags...)
			validatedImage.RepoDigests = append(validatedImage.RepoDigests, repoDigests...)
			// Store our image
			// foundImages[validatedDigest] = validatedImage
			entries = append(entries, validatedImage)
		}
	}

	if len(errs) > 0 {
		return []any{}, fmt.Errorf("%d errors:\n%w", len(errs), errors.Join(errs...))
	}

	return entries, nil
}