Move Server Pipeline Build code out of API into own package (#949)

- refactor
- create new errors to handle on them
- dedup code
- split server pipeline functionality's into dedicated functions
- add code comments to document what goes on
- add TODOs for next refactor

server/pipeline/approve.go

@@ -0,0 +1,68 @@
+// Copyright 2022 Woodpecker 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 pipeline
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/rs/zerolog/log"
+
+	"github.com/woodpecker-ci/woodpecker/server/model"
+	"github.com/woodpecker-ci/woodpecker/server/remote"
+	"github.com/woodpecker-ci/woodpecker/server/shared"
+	"github.com/woodpecker-ci/woodpecker/server/store"
+)
+
+// Approve update the status to pending for blocked build because of a gated repo
+// and start them afterwards
+func Approve(ctx context.Context, store store.Store, build *model.Build, user *model.User, repo *model.Repo) (*model.Build, error) {
+	if build.Status != model.StatusBlocked {
+		return nil, ErrBadRequest{Msg: fmt.Sprintf("cannot decline a build with status %s", build.Status)}
+	}
+
+	// fetch the build file from the database
+	configs, err := store.ConfigsForBuild(build.ID)
+	if err != nil {
+		msg := fmt.Sprintf("failure to get build config for %s. %s", repo.FullName, err)
+		log.Error().Msg(msg)
+		return nil, ErrNotFound{Msg: msg}
+	}
+
+	if build, err = shared.UpdateToStatusPending(store, *build, user.Login); err != nil {
+		return nil, fmt.Errorf("error updating build. %s", err)
+	}
+
+	var yamls []*remote.FileMeta
+	for _, y := range configs {
+		yamls = append(yamls, &remote.FileMeta{Data: y.Data, Name: y.Name})
+	}
+
+	build, buildItems, err := createBuildItems(ctx, store, build, user, repo, yamls, nil)
+	if err != nil {
+		msg := fmt.Sprintf("failure to createBuildItems for %s", repo.FullName)
+		log.Error().Err(err).Msg(msg)
+		return nil, err
+	}
+
+	build, err = start(ctx, store, build, user, repo, buildItems)
+	if err != nil {
+		msg := fmt.Sprintf("failure to start build for %s: %v", repo.FullName, err)
+		log.Error().Err(err).Msg(msg)
+		return nil, fmt.Errorf(msg)
+	}
+
+	return build, nil
+}