/*
Copyright © The ESO 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

    https://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 gitlab implements a GitLab provider for External Secrets.
package gitlab

import (
	"context"
	"crypto/tls"
	"crypto/x509"
	"errors"
	"fmt"
	"net/http"

	gitlab "gitlab.com/gitlab-org/api/client-go"
	kclient "sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"

	esv1 "github.com/external-secrets/external-secrets/apis/externalsecrets/v1"
	"github.com/external-secrets/external-secrets/runtime/constants"
	"github.com/external-secrets/external-secrets/runtime/esutils"
	"github.com/external-secrets/external-secrets/runtime/metrics"
)

// Provider satisfies the provider interface.
type Provider struct{}

// gitlabBase satisfies the provider.SecretsClient interface.
type gitlabBase struct {
	kube      kclient.Client
	store     *esv1.GitlabProvider
	storeKind string
	namespace string

	projectsClient         ProjectsClient
	projectVariablesClient ProjectVariablesClient
	groupVariablesClient   GroupVariablesClient
}

// Capabilities returns the provider supported capabilities (ReadOnly, WriteOnly, ReadWrite).
func (g *Provider) Capabilities() esv1.SecretStoreCapabilities {
	return esv1.SecretStoreReadOnly
}

// NewClient creates a new GitLab client with the given store configuration.
// It sets up the project variables client with credentials and populates projectID and environment.
func (g *Provider) NewClient(ctx context.Context, store esv1.GenericStore, kube kclient.Client, namespace string) (esv1.SecretsClient, error) {
	storeSpec := store.GetSpec()
	if storeSpec == nil || storeSpec.Provider == nil || storeSpec.Provider.Gitlab == nil {
		return nil, errors.New("no store type or wrong store type")
	}
	storeSpecGitlab := storeSpec.Provider.Gitlab

	gl := &gitlabBase{
		kube:      kube,
		store:     storeSpecGitlab,
		namespace: namespace,
		storeKind: store.GetObjectKind().GroupVersionKind().Kind,
	}

	client, err := gl.getClient(ctx, storeSpecGitlab)
	if err != nil {
		return nil, err
	}
	gl.projectsClient = client.Projects
	gl.projectVariablesClient = client.ProjectVariables
	gl.groupVariablesClient = client.GroupVariables

	return gl, nil
}

func (g *gitlabBase) getClient(ctx context.Context, provider *esv1.GitlabProvider) (*gitlab.Client, error) {
	credentials, err := g.getAuth(ctx)
	if err != nil {
		return nil, err
	}

	// Create projectVariablesClient options
	var opts []gitlab.ClientOptionFunc
	if provider.URL != "" {
		opts = append(opts, gitlab.WithBaseURL(provider.URL))
	}

	if len(provider.CABundle) > 0 || provider.CAProvider != nil {
		caCertPool := x509.NewCertPool()
		ca, err := esutils.FetchCACertFromSource(ctx, esutils.CreateCertOpts{
			CABundle:   provider.CABundle,
			CAProvider: provider.CAProvider,
			StoreKind:  g.storeKind,
			Namespace:  g.namespace,
			Client:     g.kube,
		})
		if err != nil {
			return nil, fmt.Errorf("failed to read ca bundle: %w", err)
		}
		if ok := caCertPool.AppendCertsFromPEM(ca); !ok {
			return nil, errors.New("failed to append ca bundle")
		}

		transport := &http.Transport{
			TLSClientConfig: &tls.Config{
				RootCAs:    caCertPool,
				MinVersion: tls.VersionTLS12,
			},
		}

		httpClient := &http.Client{Transport: transport}
		opts = append(opts, gitlab.WithHTTPClient(httpClient))
	}

	// ClientOptionFunc from the gitlab package can be mapped with the CRD
	// in a similar way to extend functionality of the provider

	// Create a new GitLab Client using credentials and options
	client, err := gitlab.NewClient(credentials, opts...)
	if err != nil {
		return nil, err
	}

	return client, nil
}

func (g *gitlabBase) getVariables(ref esv1.ExternalSecretDataRemoteRef, vopts *gitlab.GetProjectVariableOptions) (*gitlab.ProjectVariable, error) {
	// First attempt to get the variable
	data, _, err := g.projectVariablesClient.GetVariable(g.store.ProjectID, ref.Key, vopts)
	metrics.ObserveAPICall(constants.ProviderGitLab, constants.CallGitLabProjectVariableGet, err)

	// If successful, return immediately
	if err == nil {
		return data, nil
	}

	// If not a "not found" error or environment is already wildcard, return the error
	if !errors.Is(err, gitlab.ErrNotFound) || isEmptyOrWildcard(g.store.Environment) {
		return nil, err
	}

	// Retry with wildcard environment scope
	opts := &gitlab.GetProjectVariableOptions{Filter: &gitlab.VariableFilter{EnvironmentScope: "*"}}
	data, _, err = g.projectVariablesClient.GetVariable(g.store.ProjectID, ref.Key, opts)
	metrics.ObserveAPICall(constants.ProviderGitLab, constants.CallGitLabProjectVariableGet, err)

	if err != nil {
		return nil, fmt.Errorf("error getting variable %s from GitLab (including wildcard retry): %w", ref.Key, err)
	}

	return data, nil
}

// ValidateStore validates the GitLab store configuration.
func (g *Provider) ValidateStore(store esv1.GenericStore) (admission.Warnings, error) {
	storeSpec := store.GetSpec()
	gitlabSpec := storeSpec.Provider.Gitlab
	accessToken := gitlabSpec.Auth.SecretRef.AccessToken
	err := esutils.ValidateSecretSelector(store, accessToken)
	if err != nil {
		return nil, err
	}

	if gitlabSpec.ProjectID == "" && len(gitlabSpec.GroupIDs) == 0 {
		return nil, errors.New("projectID and groupIDs must not both be empty")
	}

	if gitlabSpec.InheritFromGroups && len(gitlabSpec.GroupIDs) > 0 {
		return nil, errors.New("defining groupIDs and inheritFromGroups = true is not allowed")
	}

	if accessToken.Key == "" {
		return nil, errors.New("accessToken.key cannot be empty")
	}

	if accessToken.Name == "" {
		return nil, errors.New("accessToken.name cannot be empty")
	}

	return nil, nil
}

// NewProvider creates a new Provider instance.
func NewProvider() esv1.Provider {
	return &Provider{}
}

// ProviderSpec returns the provider specification for registration.
func ProviderSpec() *esv1.SecretStoreProvider {
	return &esv1.SecretStoreProvider{
		Gitlab: &esv1.GitlabProvider{},
	}
}

// MaintenanceStatus returns the maintenance status of the provider.
func MaintenanceStatus() esv1.MaintenanceStatus {
	return esv1.MaintenanceStatusMaintained
}
