import type { HttpContext } from '@adonisjs/core/http'
import { getMongoDb } from '#providers/mongodb_provider'
import { verifyCwmpExchangesIndexes } from '#services/exchange_index_checker'
import { ExchangeStoreService } from '#services/exchange_store_service'

export default class HealthController {
  async checklife({ response }: HttpContext) {
    return response.json({ status: 'OK' })
  }

  async checkservice({ response }: HttpContext) {
    try {
      const db = getMongoDb()
      await db.command({ ping: 1 })

      const indexCheck = await verifyCwmpExchangesIndexes(db).catch(() => null)

      return response.json({
        status: 'OK',
        version: '1.0.0',
        indexes: indexCheck
          ? {
              cwmp_exchanges: {
                allPresent: indexCheck.allPresent,
                indexes: indexCheck.indexes,
              },
            }
          : undefined,
      })
    } catch {
      return response.status(503).json({ status: 'KO', version: '1.0.0' })
    }
  }

  /**
   * GET /api/v1/health/tr069-exchanges
   *
   * Health check endpoint for the TR-069 exchange viewer subsystem.
   * Reports:
   *  - MongoDB connectivity and latency
   *  - Active SSE connection count
   *  - Collection stats (document count, size)
   *  - Overall status: healthy / degraded / unhealthy
   *
   * Status logic:
   *  - healthy: MongoDB connected, latency < 100ms, indexes present
   *  - degraded: MongoDB connected but latency >= 100ms, or missing indexes
   *  - unhealthy: MongoDB unreachable or ping fails
   */
  async checkTr069Exchanges({ response }: HttpContext) {
    const timestamp = new Date().toISOString()
    let mongoConnected = false
    let latencyMs = -1
    let collectionStats: { count: number; sizeMb: number } | null = null
    let indexCheck: Awaited<ReturnType<typeof verifyCwmpExchangesIndexes>> | null = null

    // Check MongoDB connectivity and measure latency
    try {
      const db = getMongoDb()
      const start = Date.now()
      await db.command({ ping: 1 })
      latencyMs = Date.now() - start
      mongoConnected = true

      // Get collection stats
      const collection = db.collection('cwmp_exchanges')
      const count = await collection.estimatedDocumentCount()

      let sizeMb = 0
      try {
        const stats = await db.command({ collStats: 'cwmp_exchanges' })
        sizeMb = Math.round((stats.size / (1024 * 1024)) * 100) / 100
      } catch {
        // Collection may not exist yet or collStats may not be available
        sizeMb = 0
      }

      collectionStats = { count, sizeMb }

      // Check indexes
      indexCheck = await verifyCwmpExchangesIndexes(db)
    } catch {
      mongoConnected = false
    }

    // Get active SSE connection count
    const exchangeStore = ExchangeStoreService.getInstance()
    const activeConnections = exchangeStore.activeConnectionCount

    // Determine overall status
    let status: 'healthy' | 'degraded' | 'unhealthy'
    if (!mongoConnected) {
      status = 'unhealthy'
    } else if (latencyMs >= 100 || (indexCheck && !indexCheck.allPresent)) {
      status = 'degraded'
    } else {
      status = 'healthy'
    }

    const statusCode = status === 'unhealthy' ? 503 : 200

    return response.status(statusCode).json({
      status,
      mongodb: {
        connected: mongoConnected,
        latency_ms: latencyMs >= 0 ? latencyMs : null,
        collections: collectionStats
          ? {
              cwmp_exchanges: {
                count: collectionStats.count,
                size_mb: collectionStats.sizeMb,
              },
            }
          : null,
        indexes: indexCheck
          ? {
              allPresent: indexCheck.allPresent,
              details: indexCheck.indexes,
            }
          : null,
      },
      sse: {
        active_connections: activeConnections,
      },
      timestamp,
    })
  }
}