import { and, eq, isNull, sql } from 'drizzle-orm'
import type { IncidentType, Severity } from '../../shared/enums.ts'
import type { SessionUser } from '../auth/sessions.ts'
import { isUniqueViolation, type Db } from '../db/client.ts'
import { areas, incidentCounters, incidents, sites } from '../db/schema.ts'
import type { Notifier } from '../notifications.ts'
import { fail } from './http.ts'
import { auditIncident } from './incidents.ts'

/** Reports may be dated slightly ahead to absorb clock differences between devices. */
const MAX_CLOCK_SKEW_MS = 5 * 60 * 1000

export function parseOccurredAt(value: string): Date {
  const date = new Date(value)
  if (date.getTime() > Date.now() + MAX_CLOCK_SKEW_MS) throw fail(400, 'Occurrence time cannot be in the future')
  return date
}

export async function assertLocation(db: Db, organizationId: string, siteId: string, areaId: string | null | undefined) {
  const [site] = await db
    .select({ id: sites.id })
    .from(sites)
    .where(and(eq(sites.id, siteId), eq(sites.organizationId, organizationId), isNull(sites.archivedAt)))
  if (!site) throw fail(400, 'Unknown site')
  if (areaId) {
    const [area] = await db
      .select({ id: areas.id })
      .from(areas)
      .where(and(eq(areas.id, areaId), eq(areas.siteId, siteId)))
    if (!area) throw fail(400, 'Area must belong to the selected site')
  }
}

export interface NewReport {
  organizationId: string
  title: string
  type: IncidentType
  severity: Severity
  occurredAt: string
  siteId: string
  areaId?: string | null
  locationDetail?: string | null
  description?: string | null
  immediateAction?: string | null
  clientId?: string
  /** Signed-in reporter, or null for anonymous and kiosk reports. */
  reporter: SessionUser | null
  reporterName?: string | null
  anonymous: boolean
  kioskId?: string
}

/**
 * Files a report with the next incident number. If `clientId` was already used in the organization
 * (a retried submission), returns the existing incident instead of creating a duplicate.
 */
export async function fileReport(db: Db, notifier: Notifier, report: NewReport): Promise<{ id: string; number: number; created: boolean }> {
  const { organizationId, reporter, anonymous, kioskId, occurredAt, clientId, ...fields } = report
  await assertLocation(db, organizationId, fields.siteId, fields.areaId)
  const occurred = parseOccurredAt(occurredAt)

  const existing = async () => {
    if (!clientId) return undefined
    const [row] = await db
      .select({ id: incidents.id, number: incidents.number })
      .from(incidents)
      .where(and(eq(incidents.organizationId, organizationId), eq(incidents.clientId, clientId)))
    return row && { ...row, created: false }
  }
  const previous = await existing()
  if (previous) return previous

  try {
    const created = await db.transaction(async (tx) => {
      // Atomic increment: concurrent reports always get distinct, gap-free numbers.
      const [{ lastNumber }] = await tx
        .insert(incidentCounters)
        .values({ organizationId, lastNumber: 1 })
        .onConflictDoUpdate({ target: incidentCounters.organizationId, set: { lastNumber: sql`${incidentCounters.lastNumber} + 1` } })
        .returning({ lastNumber: incidentCounters.lastNumber })
      const [incident] = await tx
        .insert(incidents)
        .values({
          ...fields,
          occurredAt: occurred,
          organizationId,
          number: lastNumber,
          clientId,
          anonymous,
          reporterId: anonymous ? null : (reporter?.id ?? null),
          reporterName: anonymous ? null : (fields.reporterName ?? null),
          channel: kioskId ? 'kiosk' : 'web',
          kioskId,
        })
        .returning({ id: incidents.id, number: incidents.number })
      await auditIncident(tx, anonymous ? null : reporter, organizationId, incident.id, 'create', {
        number: lastNumber,
        title: fields.title,
        type: fields.type,
        severity: fields.severity,
        ...(kioskId ? { kioskId } : {}),
      })
      return incident
    })
    notifier.incidentReported(created.id)
    return { ...created, created: true }
  } catch (error) {
    // Two copies of the same submission raced; the other one won.
    if (clientId && isUniqueViolation(error)) {
      const winner = await existing()
      if (winner) return winner
    }
    throw error
  }
}