// Author: Simon-Pierre Boucher — contact@spboucher.ai
//
// A training run: identity, config, directories, and the state machine
// (RunSupervisor is the only mutator; every transition is persisted
// atomically by RunStore).
import Foundation

enum RunState: String, Codable, CaseIterable {
    case queued, launching, running, finishing, finished, failed, stopped

    var isActive: Bool {
        switch self {
        case .launching, .running, .finishing: return true
        default: return false
        }
    }

    // Legal transitions — RunSupervisor refuses anything else.
    static let transitions: [RunState: Set<RunState>] = [
        .queued: [.launching, .stopped],
        .launching: [.running, .failed, .stopped],
        .running: [.finishing, .finished, .failed, .stopped],
        .finishing: [.finished, .failed, .stopped],
        .finished: [], .failed: [], .stopped: [],
    ]
}

struct Run: Codable, Identifiable, Equatable {
    var id: UUID = UUID()
    var name: String
    var createdAt: Date
    var state: RunState = .queued
    var config: ForgeConfig
    var datasetPath: String
    var outDirectory: String        // <workspace>/runs/<name>-<timestamp>
    var resumeCheckpoint: String?   // forge train --resume
    var pid: Int32?                 // live forge process (crash recovery)
    var lastStep: Int?
    var lastTrainLoss: Double?
    var bestValLoss: Double?
    var bestValStep: Int?
    var exitCode: Int32?
    var failureReason: String?

    var logCSVPath: String { outDirectory + "/log.csv" }
    var runLogPath: String { outDirectory + "/run.log" }
    var configPath: String { outDirectory + "/config.json" }

    var progress: Double {
        guard let step = lastStep, config.train.maxSteps > 0 else { return 0 }
        return min(1.0, Double(step + 1) / Double(config.train.maxSteps))
    }
}