/**
 * Configuration shape and validation for dsh-session-archive, shared by the
 * host schema and the client settings form. Pure logic.
 * @module @linxin666/dsh-session-archive/core/config
 */

export interface SessionArchiveConfig {
  enabled?: boolean
  /** Auto-archive sessions inactive for more than this many days. Default off. */
  autoArchiveEnabled?: boolean
  /** Inactivity threshold in days for auto-archive (1-3650). */
  autoArchiveDays?: number
  /** Physically delete archived sessions older than this many days after archive time. Default off. */
  autoDeleteEnabled?: boolean
  /** Archive retention in days for auto-delete (1-3650). */
  autoDeleteDays?: number
  /**
   * Default off. When enabled, a session found already archived with no ledger
   * entry (archived from the official sidebar, which never reaches this
   * plugin) gets one backfilled `observed` entry at the moment the plugin
   * observes it, so the retention clock starts for that session.
   */
  recordManualArchive?: boolean
  /** Scheduler cadence in minutes (15-1440). */
  checkIntervalMin?: number
}

/**
 * One config field as the 0.1.7 Host delivers it to the running plugin: every
 * field the schema declares volatile arrives as a stable reference whose
 * `get()` reads the value committed for this instance (a settings write updates
 * the reference in place, without remounting the row).
 */
export interface ConfigFieldRef<T> {
  /** @returns the value currently committed for the running instance. */
  get(): T | undefined
}

/** One activation field: a volatile reference, or a plain value (profile patches, tests). */
export type ConfigField<T> = T | ConfigFieldRef<T> | undefined

/**
 * The settings the Host hands this plugin's activation (its own Config schema,
 * resolved over the composition base and the profile's user layer).
 */
export interface SessionArchiveConfigFields {
  enabled?: ConfigField<boolean>
  autoArchiveEnabled?: ConfigField<boolean>
  autoArchiveDays?: ConfigField<number>
  autoDeleteEnabled?: ConfigField<boolean>
  autoDeleteDays?: ConfigField<number>
  recordManualArchive?: ConfigField<boolean>
  checkIntervalMin?: ConfigField<number>
}

/**
 * Read one activation field's current value. A volatile reference is read at
 * call time, so the caller always sees the latest committed value.
 */
export function readConfigField<T>(field: ConfigField<T>): T | undefined {
  if (field === undefined) return undefined
  const ref = field as ConfigFieldRef<T>
  return typeof ref.get === 'function' ? ref.get() : field as T
}

/**
 * Read the effective settings of one activation. The 0.1.7 model keeps no
 * separate settings document: the plugin's own Config is what the Host serves
 * and what the row is activated with, so this is the only settings source.
 * @param config - the config the Host passed to the activation.
 * @returns the raw field values, defaults left to {@link resolveAutoConfig}.
 */
export function readArchiveConfig(config?: SessionArchiveConfigFields): SessionArchiveConfig {
  return {
    enabled: readConfigField(config?.enabled),
    autoArchiveEnabled: readConfigField(config?.autoArchiveEnabled),
    autoArchiveDays: readConfigField(config?.autoArchiveDays),
    autoDeleteEnabled: readConfigField(config?.autoDeleteEnabled),
    autoDeleteDays: readConfigField(config?.autoDeleteDays),
    recordManualArchive: readConfigField(config?.recordManualArchive),
    checkIntervalMin: readConfigField(config?.checkIntervalMin),
  }
}

export interface ResolvedAutoConfig {
  enabled: boolean
  autoArchiveEnabled: boolean
  autoArchiveDays: number
  autoDeleteEnabled: boolean
  autoDeleteDays: number
  recordManualArchive: boolean
  checkIntervalMin: number
}

export const AUTO_ARCHIVE_DAYS_MIN = 1
export const AUTO_ARCHIVE_DAYS_MAX = 3650
export const AUTO_DELETE_DAYS_MIN = 1
export const AUTO_DELETE_DAYS_MAX = 3650
export const CHECK_INTERVAL_MIN_MIN = 15
export const CHECK_INTERVAL_MIN_MAX = 1440

export const DEFAULT_AUTO_CONFIG: ResolvedAutoConfig = {
  enabled: true,
  autoArchiveEnabled: false,
  autoArchiveDays: 7,
  autoDeleteEnabled: false,
  autoDeleteDays: 7,
  recordManualArchive: false,
  checkIntervalMin: 60,
}

/** Validate one day-threshold field; returns the rounded value or undefined when invalid. */
export function validateDays(value: unknown, min: number, max: number): number | undefined {
  if (typeof value !== 'number' || !Number.isFinite(value)) return undefined
  const rounded = Math.round(value)
  if (rounded < min || rounded > max) return undefined
  return rounded
}

/**
 * Coerce a raw config into resolved values. Invalid or out-of-range fields
 * fall back to defaults — the settings UI validates before saving, and this
 * guards profile-patch hand-written values.
 */
export function resolveAutoConfig(config?: SessionArchiveConfig): ResolvedAutoConfig {
  const days = validateDays(config?.autoArchiveDays, AUTO_ARCHIVE_DAYS_MIN, AUTO_ARCHIVE_DAYS_MAX)
  const retain = validateDays(config?.autoDeleteDays, AUTO_DELETE_DAYS_MIN, AUTO_DELETE_DAYS_MAX)
  const interval = validateDays(config?.checkIntervalMin, CHECK_INTERVAL_MIN_MIN, CHECK_INTERVAL_MIN_MAX)
  return {
    enabled: config?.enabled ?? DEFAULT_AUTO_CONFIG.enabled,
    autoArchiveEnabled: config?.autoArchiveEnabled ?? DEFAULT_AUTO_CONFIG.autoArchiveEnabled,
    autoArchiveDays: days ?? DEFAULT_AUTO_CONFIG.autoArchiveDays,
    autoDeleteEnabled: config?.autoDeleteEnabled ?? DEFAULT_AUTO_CONFIG.autoDeleteEnabled,
    autoDeleteDays: retain ?? DEFAULT_AUTO_CONFIG.autoDeleteDays,
    recordManualArchive: config?.recordManualArchive ?? DEFAULT_AUTO_CONFIG.recordManualArchive,
    checkIntervalMin: interval ?? DEFAULT_AUTO_CONFIG.checkIntervalMin,
  }
}