main.js

const core = require('@actions/core')
const github = require('@actions/github')

async function main() {
    try {
        const token = core.getInput("github_token", { required: true })
        const numbers = core.getInput("numbers")
        const owner = core.getInput("owner")
        const repository = core.getInput("repository")
        const branches = core.getInput("branches")
        const exclude = core.getInput("exclude")
        const prefix = core.getInput("prefix")
        const suffix = core.getInput("suffix")
        const soft_fail = core.getInput("soft_fail")

        const client = github.getOctokit(token)

        let branchesToDelete = branches ? branches.split(",") : []

        // get all branches from repository
        const response = await client.repos.listBranches({
            ...github.context.repo
        })

        console.log("==> Found " + response.data.length + " branches")

        for (const branch of response.data) {
            branchesToDelete.push(branch.name)
        }
        console.log("==> Branches to delete: " + branchesToDelete)
        if (numbers) {
            for (const number of numbers.split(",")) {
                const pull = await client.pulls.get({
                    ...github.context.repo,
                    pull_number: number
                })
                branchesToDelete.push(pull.data.head.ref)
            }
        }

        console.log("==> Branches to delete: " + branchesToDelete)
        console.log("==> Number to delete: " + branchesToDelete.length)

        let ownerOfRepository = owner ? owner : github.context.repo.owner
        let repositoryContainingBranches = repository ? repository : github.context.repo.repo

        for (let branch of branchesToDelete) {
            if (prefix)
                branch = prefix + branch
            if (suffix)
                branch = branch + suffix
            if (exclude && exclude.includes(branch)) {
                return;
            }
            console.log("==> Deleting \"" + ownerOfRepository + "/" + repositoryContainingBranches + "/" + branch + "\" branch")

            try {
                await client.git.deleteRef({
                    owner: ownerOfRepository,
                    repo: repositoryContainingBranches,
                    ref: "heads/" + branch
                })
            } catch (error) {
                const shouldFailSoftly = (soft_fail === 'true');

                if (shouldFailSoftly)
                    core.warning(error.message)
                else
                    core.setFailed(error.message)
            }
        }
    } catch (error) {
        core.setFailed(error.message)
    }
}

main()