import type { PluginInput } from "@opencode-ai/plugin"
import type { Platform } from "./session-notification-sender"

type SessionNotificationConfig = {
  title: string
  message: string
  playSound: boolean
  soundPath: string
  idleConfirmationDelay: number
  skipIfIncompleteTodos: boolean
  maxTrackedSessions: number
}

export function createIdleNotificationScheduler(options: {
  ctx: PluginInput
  platform: Platform
  config: SessionNotificationConfig
  hasIncompleteTodos: (ctx: PluginInput, sessionID: string) => Promise<boolean>
  send: (ctx: PluginInput, platform: Platform, title: string, message: string) => Promise<void>
  playSound: (ctx: PluginInput, platform: Platform, soundPath: string) => Promise<void>
}) {
  const notifiedSessions = new Set<string>()
  const pendingTimers = new Map<string, ReturnType<typeof setTimeout>>()
  const sessionActivitySinceIdle = new Set<string>()
  const notificationVersions = new Map<string, number>()
  const executingNotifications = new Set<string>()

  function cleanupOldSessions(): void {
    const maxSessions = options.config.maxTrackedSessions
    if (notifiedSessions.size > maxSessions) {
      const sessionsToRemove = Array.from(notifiedSessions).slice(0, notifiedSessions.size - maxSessions)
      sessionsToRemove.forEach((id) => notifiedSessions.delete(id))
    }
    if (sessionActivitySinceIdle.size > maxSessions) {
      const sessionsToRemove = Array.from(sessionActivitySinceIdle).slice(0, sessionActivitySinceIdle.size - maxSessions)
      sessionsToRemove.forEach((id) => sessionActivitySinceIdle.delete(id))
    }
    if (notificationVersions.size > maxSessions) {
      const sessionsToRemove = Array.from(notificationVersions.keys()).slice(0, notificationVersions.size - maxSessions)
      sessionsToRemove.forEach((id) => notificationVersions.delete(id))
    }
    if (executingNotifications.size > maxSessions) {
      const sessionsToRemove = Array.from(executingNotifications).slice(0, executingNotifications.size - maxSessions)
      sessionsToRemove.forEach((id) => executingNotifications.delete(id))
    }
  }

  function cancelPendingNotification(sessionID: string): void {
    const timer = pendingTimers.get(sessionID)
    if (timer) {
      clearTimeout(timer)
      pendingTimers.delete(sessionID)
    }
    sessionActivitySinceIdle.add(sessionID)
    notificationVersions.set(sessionID, (notificationVersions.get(sessionID) ?? 0) + 1)
  }

  function markSessionActivity(sessionID: string): void {
    cancelPendingNotification(sessionID)
    if (!executingNotifications.has(sessionID)) {
      notifiedSessions.delete(sessionID)
    }
  }

  async function executeNotification(sessionID: string, version: number): Promise<void> {
    if (executingNotifications.has(sessionID)) {
      pendingTimers.delete(sessionID)
      return
    }

    if (notificationVersions.get(sessionID) !== version) {
      pendingTimers.delete(sessionID)
      return
    }

    if (sessionActivitySinceIdle.has(sessionID)) {
      sessionActivitySinceIdle.delete(sessionID)
      pendingTimers.delete(sessionID)
      return
    }

    if (notifiedSessions.has(sessionID)) {
      pendingTimers.delete(sessionID)
      return
    }

    executingNotifications.add(sessionID)
    try {
      if (options.config.skipIfIncompleteTodos) {
        const hasPendingWork = await options.hasIncompleteTodos(options.ctx, sessionID)
        if (notificationVersions.get(sessionID) !== version) {
          return
        }
        if (hasPendingWork) return
      }

      if (notificationVersions.get(sessionID) !== version) {
        return
      }

      if (sessionActivitySinceIdle.has(sessionID)) {
        sessionActivitySinceIdle.delete(sessionID)
        return
      }

      notifiedSessions.add(sessionID)

      await options.send(options.ctx, options.platform, options.config.title, options.config.message)

      if (options.config.playSound && options.config.soundPath) {
        await options.playSound(options.ctx, options.platform, options.config.soundPath)
      }
    } finally {
      executingNotifications.delete(sessionID)
      pendingTimers.delete(sessionID)
      if (sessionActivitySinceIdle.has(sessionID)) {
        notifiedSessions.delete(sessionID)
        sessionActivitySinceIdle.delete(sessionID)
      }
    }
  }

  function scheduleIdleNotification(sessionID: string): void {
    if (notifiedSessions.has(sessionID)) return
    if (pendingTimers.has(sessionID)) return
    if (executingNotifications.has(sessionID)) return

    sessionActivitySinceIdle.delete(sessionID)

    const currentVersion = (notificationVersions.get(sessionID) ?? 0) + 1
    notificationVersions.set(sessionID, currentVersion)

    const timer = setTimeout(() => {
      executeNotification(sessionID, currentVersion)
    }, options.config.idleConfirmationDelay)

    pendingTimers.set(sessionID, timer)
    cleanupOldSessions()
  }

  function deleteSession(sessionID: string): void {
    cancelPendingNotification(sessionID)
    notifiedSessions.delete(sessionID)
    sessionActivitySinceIdle.delete(sessionID)
    notificationVersions.delete(sessionID)
    executingNotifications.delete(sessionID)
  }

  return {
    markSessionActivity,
    scheduleIdleNotification,
    deleteSession,
  }
}