import Foundation
import IndieSync

/// On-disk JSON shape for each aggregate. Independent from the SwiftData cache
/// entities so the wire format can evolve without dragging the cache schema.
///
/// One document = one aggregate root:
///   • `SplitDocument`   embeds its `[ExerciseDocument]`   → `Splits/<ULID>.json`
///   • `WorkoutDocument` embeds its `[WorkoutLogDocument]` → `Workouts/YYYY/MM/<ULID>.json`
///
/// `schemaVersion` lets us migrate old files on read without forcing a rewrite
/// at sync time, and forward-gates files written by a newer app version.
/// These documents are also the wire format for the iPhone↔Watch bridge.

// MARK: - Split

struct SplitDocument: Codable, Sendable, Equatable, Identifiable {
    var schemaVersion: Int
    var id: String                 // ULID
    var name: String
    var color: String
    var systemImage: String
    var order: Int
    var createdAt: Date
    var updatedAt: Date
    var exercises: [ExerciseDocument]
    /// Raw `WorkoutActivityType`; nil → traditional strength training. Optional and
    /// deliberately NOT schema-bumped: it's a minor categorization preference, so an
    /// older app dropping it on rewrite (reverting to the default) is preferable to
    /// quarantining the user's whole routine.
    var activityType: Int?

    // Bumped 1→2 when the weight-reminder fields (`weightLastUpdated`,
    // `weightReminderWeeks`) and `category` were removed and `machineSettings` was
    // added. Removing required fields means older apps can no longer decode new
    // files, so the forward-gate must quarantine them rather than let an older app
    // silently rewrite them.
    static let currentSchemaVersion = 2

    var relativePath: String { "Splits/\(id).json" }
}

struct ExerciseDocument: Codable, Sendable, Equatable, Identifiable {
    var id: String                 // ULID
    var name: String
    var order: Int
    var sets: Int
    var reps: Int
    var weight: Int
    var loadType: Int
    var durationSeconds: Int       // total seconds (0 when not a timed exercise)
    /// Ordered, user-defined comfort settings for machine-based exercises (seat
    /// height, back rest incline, pin position…). `nil` → not a machine exercise;
    /// empty → a machine exercise with nothing recorded yet. This optionality
    /// doubles as the machine-based flag — there is no separate Bool.
    var machineSettings: [MachineSetting]? = nil
}

/// A single free-form comfort setting for a machine-based exercise. `value` is a
/// string, not a number, because machine dials aren't uniformly numeric ("3rd
/// hole", "45°"). Ordered within `ExerciseDocument.machineSettings`.
struct MachineSetting: Codable, Sendable, Equatable {
    var name: String    // "Seat Height", "Back Rest Incline"
    var value: String   // "4", "3rd hole", "45°" — free-form; machine dials aren't uniformly numeric
}

// MARK: - Workout

struct WorkoutDocument: Codable, Sendable, Equatable, Identifiable {
    var schemaVersion: Int
    var id: String                 // ULID (chronological)
    var splitID: String?
    var splitName: String?
    var start: Date
    var end: Date?
    var status: String             // WorkoutStatus raw value
    var createdAt: Date
    var updatedAt: Date
    var logs: [WorkoutLogDocument]
    /// Health metrics captured for a finished workout (watch sensors) or estimated
    /// by the phone. Nil until the workout completes and a writer fills it in. The
    /// presence of `metrics.healthKitWorkoutUUID` is the dedupe signal that keeps the
    /// watch and the phone from both writing the same workout to Health.
    var metrics: WorkoutMetrics?

    // Bumped 1→2 when `metrics` was added: the captured HR/calorie data is
    // irreplaceable, so the forward-gate must quarantine these files on older apps
    // rather than let them strip `metrics` on rewrite.
    // Bumped 2→3 when the derived `completed` flag was removed from
    // `WorkoutLogDocument` and `machineSettings` was added to it. Dropping a
    // required field means older apps can no longer decode new files, so the
    // forward-gate must quarantine them.
    static let currentSchemaVersion = 3

    var relativePath: String { Self.relativePath(id: id, start: start) }

    static func relativePath(id: String, start: Date) -> String {
        let cal = Calendar(identifier: .gregorian)
        let comps = cal.dateComponents([.year, .month], from: start)
        let year = comps.year ?? 1970
        let month = comps.month ?? 1
        return String(format: "Workouts/%04d/%02d/%@.json", year, month, id)
    }
}

extension WorkoutDocument {
    /// Derive the aggregate `status` + `end` from the current logs. A log that is
    /// `.completed` or `.skipped` counts as *resolved*; a workout whose logs are all
    /// resolved is finished (`.completed`, with `end` stamped). This is the single
    /// source of the status-from-logs rule — every screen that mutates logs calls it,
    /// so an ended workout (remaining exercises skipped) stays finished no matter which
    /// screen the next edit comes from.
    mutating func recomputeStatusFromLogs() {
        let statuses: [WorkoutStatus] = logs.map { WorkoutStatus(rawValue: $0.status) ?? .notStarted }
        let isResolved: (WorkoutStatus) -> Bool = { $0 == .completed || $0 == .skipped }

        let allResolved = !statuses.isEmpty && statuses.allSatisfy(isResolved)
        let anyStarted = statuses.contains { $0 != .notStarted }

        if allResolved {
            status = WorkoutStatus.completed.rawValue
            end = Date()
        } else if anyStarted {
            status = WorkoutStatus.inProgress.rawValue
            end = nil
        } else {
            status = WorkoutStatus.notStarted.rawValue
            end = nil
        }
    }

    /// End the workout now, keeping progress: mark every not-completed log as skipped, then
    /// recompute so it resolves to `.completed` (with `end` stamped). This is the
    /// "End Workout → Save" operation, shared by the in-workout menu and the
    /// start-a-new-split prompt.
    mutating func endKeepingProgress() {
        for i in logs.indices where (WorkoutStatus(rawValue: logs[i].status) ?? .notStarted) != .completed {
            logs[i].transition(to: .skipped)
        }
        recomputeStatusFromLogs()
        updatedAt = Date()
    }
}

struct WorkoutLogDocument: Codable, Sendable, Equatable, Identifiable {
    var id: String                 // ULID
    var exerciseName: String
    var order: Int
    var sets: Int
    var reps: Int
    var weight: Int
    var loadType: Int
    var durationSeconds: Int       // total seconds (0 when not a timed exercise)
    var currentStateIndex: Int
    var status: String             // WorkoutStatus raw value
    var notes: String?
    var date: Date
    /// Snapshot of the exercise's machine comfort settings at plan time (like the
    /// sets/reps/weight snapshot). `nil` → not a machine exercise; empty → a machine
    /// exercise with nothing recorded yet.
    var machineSettings: [MachineSetting]? = nil
    /// When the log first moved to `.inProgress` / last moved to `.completed`.
    /// Optional additions — absent in files written before they existed.
    var startedAt: Date? = nil
    var completedAt: Date? = nil
}

extension WorkoutLogDocument {
    /// Build a fresh plan-time log from a split's exercise. Snapshots the plan
    /// fields (sets/reps/weight/duration) *and* the machine comfort settings, so a
    /// running workout carries the exercise's settings as its own editable copy —
    /// `nil` stays `nil` (not a machine exercise), and `[]` stays `[]` (machine
    /// exercise, nothing recorded yet). Every "start a workout" / "add exercise to
    /// a workout" path funnels through here so the snapshot can't drift per site.
    init(planFrom exercise: ExerciseDocument, order: Int, date: Date) {
        self.init(
            id: ULID.make(),
            exerciseName: exercise.name,
            order: order,
            sets: exercise.sets,
            reps: exercise.reps,
            weight: exercise.weight,
            loadType: exercise.loadType,
            durationSeconds: exercise.durationSeconds,
            currentStateIndex: 0,
            status: WorkoutStatus.notStarted.rawValue,
            notes: nil,
            date: date,
            machineSettings: exercise.machineSettings
        )
    }

    /// Move to a new status, keeping the started/completed timestamps consistent.
    /// Every screen that flips a log's status (phone and watch) goes through here,
    /// so the timestamps can't drift per-call-site. Completion is derived from
    /// `status` (`completed == (status == WorkoutStatus.completed.rawValue)`), so
    /// there's no separate flag to keep in sync.
    mutating func transition(to newStatus: WorkoutStatus) {
        status = newStatus.rawValue
        switch newStatus {
        case .notStarted:
            startedAt = nil
            completedAt = nil
        case .inProgress:
            if startedAt == nil { startedAt = Date() }
            completedAt = nil
        case .completed:
            if completedAt == nil { completedAt = Date() }
        case .skipped:
            completedAt = nil
        }
    }
}

// MARK: - Workout health metrics

/// Health metrics for one finished workout. Embedded in `WorkoutDocument` so they
/// ride the existing iCloud + Watch-bridge paths with the rest of the workout.
/// Every field except `source`/`recordedAt` is optional — a phone estimate carries
/// only calories + volume, while a watch session fills in heart rate too.
struct WorkoutMetrics: Codable, Sendable, Equatable {
    var activeEnergyKcal: Double?
    var avgHeartRate: Double?      // bpm
    var maxHeartRate: Double?      // bpm
    var minHeartRate: Double?      // bpm
    var totalVolume: Double?       // Σ sets×reps×weight across weighted logs
    var hrZoneSeconds: [Double]?   // seconds spent in each of 5 HR zones (low→high)
    var healthKitWorkoutUUID: String?
    var source: MetricSource
    var recordedAt: Date
}

// MARK: - Forward-compatibility gate

// `VersionedDocument` (the `isReadable` quarantine gate for files written by a
// newer app version), `Tombstone`, and `DocumentCoder` all live in IndieSync now.
extension SplitDocument: VersionedDocument {}
extension WorkoutDocument: VersionedDocument {}