labelSyncer.ts

import { GitHub } from './github'
import { Label } from './issue'

export class LabelSyncer {
    public static syncLabels(gitHubSource: GitHub, gitHubTarget: GitHub): Promise<void> {
        // Retrieve labels in source repo
        let sourceRepoLabels: Label[] = []
        return gitHubSource
            .getLabels()
            .then(response => {
                sourceRepoLabels = response.data
            })
            .catch(err => {
                console.error('Failed to retrieve source repo labels', err)
            })
            .then(() => {
                // Retrieve labels in target repo
                let targetRepoLabels: Label[] = []
                gitHubTarget
                    .getLabels()
                    .then(response => {
                        targetRepoLabels = response.data
                    })
                    .catch(err => {
                        console.error('Failed to retrieve target repo labels', err)
                    })
                    .then(() => {
                        // Filter source repo labels: remove all that from list that are already contained in target (= delta)
                        sourceRepoLabels = sourceRepoLabels.filter(
                            label =>
                                targetRepoLabels
                                    // Match by name and description, as IDs may vary across repos
                                    .find(
                                        targetEntry =>
                                            targetEntry.name == label.name &&
                                            targetEntry.description == label.description
                                    ) == undefined
                        )

                        // Create delta of missing issues in target
                        Promise.all(
                            sourceRepoLabels.map(element => {
                                return gitHubTarget
                                    .createLabel(element.name, element.description || '', element.color)
                                    .then(() => `Successfully synced label ${element.name}`)
                                    .catch(err => `Failed to sync label ${element.name}: ${err}`)
                            })
                        )
                            .then(results => {
                                results.forEach(element => console.log(element))
                            })
                            .then((): null => {
                                console.log('Done')
                                return null
                            })
                    })
            })
    }
}