func prepare()

in Sources/XCRemoteCache/Commands/Prepare/Prepare.swift [75:121]
37 lines of code
7 McCabe index (conditional complexity)

    func prepare() throws -> PrepareResult {
        do {
            guard fileAccessor.fileExists(atPath: PhaseCacheModeController.xcodeSelectLink.path) else {
                throw PrepareError.missingXcodeSelectDirectory
            }

            let commonSha: String
            do {
                commonSha = try gitClient.getCommonPrimarySha()
            } catch let GitClientError.noCommonShaWithPrimaryRepo(remoteName, error) {
                guard context.gracefullyHandleMissingCommonSha else {
                    throw GitClientError.noCommonShaWithPrimaryRepo(remoteName: remoteName, error: error)
                }
                infoLog("Cannot find a common sha with the primary branch: \(error). Gracefully disabling remote cache")
                try disable()
                return .failed
            }

            if context.offline {
                // Optimistically take first common sha
                return try enableCommit(sha: commonSha, age: 0)
            }
            // Remove old artifacts from local cache
            cacheInvalidator.invalidateArtifacts()

            // calling `git` is expensive, so optimistically tring the common sha first
            if try isArtifactAvailable(for: commonSha) {
                return try enableCommit(sha: commonSha, age: 0)
            }
            // Find a list of all potential commits that may have artifacts that can be used
            let allCommonCommits = try gitClient.getPreviousCommits(starting: commonSha, maximum: context.maximumSha)
            // First commit was checked already
            for (index, sha) in allCommonCommits.dropFirst().enumerated() {
                // Check if the marker file for a `sha` commit is available on the remote cache server
                if try isArtifactAvailable(for: sha) {
                    // adding 1 because current HEAD was already checked
                    return try enableCommit(sha: sha, age: index + 1)
                }
            }
            infoLog("No artifacts available")
            try disable()
        } catch {
            try disable()
            throw error
        }
        return .failed
    }