// Author: Simon-Pierre Boucher — contact@spboucher.ai
//
// Run registry with atomic persistence: every mutation writes
// runs.json.tmp then renames — the app survives kill -9 at any moment with
// either the old or the new registry, never a torn one.
import Foundation

@Observable
final class RunStore {
    private(set) var runs: [Run] = []
    let workspaceURL: URL
    private var registryURL: URL { workspaceURL.appendingPathComponent("runs.json") }

    init(workspace: URL) {
        workspaceURL = workspace
        load()
    }

    func load() {
        guard let data = try? Data(contentsOf: registryURL),
              let decoded = try? JSONDecoder().decode([Run].self, from: data) else {
            return
        }
        runs = decoded
    }

    func upsert(_ run: Run) {
        if let i = runs.firstIndex(where: { $0.id == run.id }) {
            runs[i] = run
        } else {
            runs.append(run)
        }
        persist()
    }

    func remove(_ run: Run) {
        runs.removeAll { $0.id == run.id }
        persist()
    }

    private func persist() {
        do {
            let enc = JSONEncoder()
            enc.outputFormatting = [.prettyPrinted, .sortedKeys]
            enc.dateEncodingStrategy = .iso8601
            let data = try enc.encode(runs)
            let tmp = registryURL.appendingPathExtension("tmp")
            try FileManager.default
                .createDirectory(at: workspaceURL, withIntermediateDirectories: true)
            try data.write(to: tmp, options: .atomic)
            _ = try FileManager.default.replaceItemAt(registryURL, withItemAt: tmp)
        } catch {
            // Persistence failure must be visible, never silent: kept on the
            // store for the UI to surface.
            lastPersistError = error.localizedDescription
        }
    }

    private(set) var lastPersistError: String?
}