import { and, asc, eq, exists, or, type SQL } from 'drizzle-orm'
import { alias } from 'drizzle-orm/pg-core'
import type { Attachment, CorrectiveAction, Incident, IncidentDetail, Investigation, RootCause } from '../../shared/api-types.ts'
import { hasRole } from '../../shared/enums.ts'
import { incidentReference } from '../../shared/format.ts'
import { availableTransitions } from '../../shared/workflow.ts'
import type { SessionUser } from '../auth/sessions.ts'
import type { Db } from '../db/client.ts'
import { areas, attachments, correctiveActions, incidents, investigations, rootCauses, sites, users } from '../db/schema.ts'
import { audit } from './audit.ts'
import { iso, localDate } from './dates.ts'
import { fail } from './http.ts'

const reporters = alias(users, 'reporter')

export function selectIncidents(db: Db) {
  return db
    .select({ incident: incidents, siteName: sites.name, areaName: areas.name, reporterName: reporters.name })
    .from(incidents)
    .innerJoin(sites, eq(sites.id, incidents.siteId))
    .leftJoin(areas, eq(areas.id, incidents.areaId))
    .leftJoin(reporters, eq(reporters.id, incidents.reporterId))
}

type IncidentRow = Awaited<ReturnType<ReturnType<typeof selectIncidents>['execute']>>[number]

export function toIncident({ incident, siteName, areaName, reporterName }: IncidentRow): Incident {
  return {
    id: incident.id,
    number: incident.number,
    reference: incidentReference(incident.number),
    title: incident.title,
    type: incident.type,
    severity: incident.severity,
    status: incident.status,
    occurredAt: iso(incident.occurredAt),
    reportedAt: iso(incident.createdAt),
    updatedAt: iso(incident.updatedAt),
    closedAt: iso(incident.closedAt),
    site: { id: incident.siteId, name: siteName },
    area: incident.areaId ? { id: incident.areaId, name: areaName ?? '' } : null,
    locationDetail: incident.locationDetail,
    description: incident.description,
    immediateAction: incident.immediateAction,
    anonymous: incident.anonymous,
    reporter: incident.reporterId ? { id: incident.reporterId, name: reporterName ?? '' } : null,
  }
}

/**
 * Supervisors and above see every incident in their organization. Reporters see incidents they
 * reported, plus any where they are assigned a corrective action.
 */
export function visibleTo(db: Db, user: SessionUser): SQL | undefined {
  const inOrg = eq(incidents.organizationId, user.organizationId)
  if (hasRole(user.role, 'supervisor')) return inOrg
  const assigned = db
    .select({ id: correctiveActions.id })
    .from(correctiveActions)
    .where(and(eq(correctiveActions.incidentId, incidents.id), eq(correctiveActions.assigneeId, user.id)))
  return and(inOrg, or(eq(incidents.reporterId, user.id), exists(assigned)))
}

export async function findIncident(db: Db, user: SessionUser, number: number) {
  const [row] = await selectIncidents(db).where(and(visibleTo(db, user), eq(incidents.number, number)))
  if (!row) throw fail(404, 'Incident not found')
  return row
}

const assignees = alias(users, 'assignee')
const verifiers = alias(users, 'verifier')

export function selectActions(db: Db) {
  return db
    .select({
      action: correctiveActions,
      incidentNumber: incidents.number,
      incidentTitle: incidents.title,
      assigneeName: assignees.name,
      verifierName: verifiers.name,
    })
    .from(correctiveActions)
    .innerJoin(incidents, eq(incidents.id, correctiveActions.incidentId))
    .leftJoin(assignees, eq(assignees.id, correctiveActions.assigneeId))
    .leftJoin(verifiers, eq(verifiers.id, correctiveActions.verifiedById))
}

type ActionRow = Awaited<ReturnType<ReturnType<typeof selectActions>['execute']>>[number]

export const isOpenAction = (status: string) => status === 'open' || status === 'in_progress'

export function toAction({ action, incidentNumber, incidentTitle, assigneeName, verifierName }: ActionRow, today = localDate()): CorrectiveAction {
  return {
    id: action.id,
    incident: { number: incidentNumber, reference: incidentReference(incidentNumber), title: incidentTitle },
    rootCauseId: action.rootCauseId,
    kind: action.kind,
    title: action.title,
    description: action.description,
    assignee: action.assigneeId ? { id: action.assigneeId, name: assigneeName ?? '' } : null,
    dueDate: action.dueDate,
    status: action.status,
    overdue: isOpenAction(action.status) && !!action.dueDate && action.dueDate < today,
    completedAt: iso(action.completedAt),
    verifiedBy: action.verifiedById ? { id: action.verifiedById, name: verifierName ?? '' } : null,
    verifiedAt: iso(action.verifiedAt),
    createdAt: iso(action.createdAt),
  }
}

export function toAttachment(row: typeof attachments.$inferSelect, uploaderName: string | null): Attachment {
  return {
    id: row.id,
    fileName: row.fileName,
    contentType: row.contentType,
    sizeBytes: row.sizeBytes,
    uploadedBy: row.uploadedById ? { id: row.uploadedById, name: uploaderName ?? '' } : null,
    createdAt: iso(row.createdAt),
    url: `/api/attachments/${row.id}`,
  }
}

export async function loadDetail(db: Db, user: SessionUser, number: number): Promise<IncidentDetail> {
  const row = await findIncident(db, user, number)
  const incidentId = row.incident.id
  const leads = alias(users, 'lead')

  const [investigationRow] = await db
    .select({ investigation: investigations, leadName: leads.name })
    .from(investigations)
    .leftJoin(leads, eq(leads.id, investigations.leadId))
    .where(eq(investigations.incidentId, incidentId))

  const causes = investigationRow
    ? await db.select().from(rootCauses).where(eq(rootCauses.investigationId, investigationRow.investigation.id)).orderBy(asc(rootCauses.createdAt))
    : []
  const actionRows = await selectActions(db).where(eq(correctiveActions.incidentId, incidentId)).orderBy(asc(correctiveActions.createdAt))
  const uploaders = alias(users, 'uploader')
  const files = await db
    .select({ file: attachments, uploaderName: uploaders.name })
    .from(attachments)
    .leftJoin(uploaders, eq(uploaders.id, attachments.uploadedById))
    .where(eq(attachments.incidentId, incidentId))
    .orderBy(asc(attachments.createdAt))

  const investigation: Investigation | null = investigationRow
    ? {
        id: investigationRow.investigation.id,
        lead: investigationRow.investigation.leadId ? { id: investigationRow.investigation.leadId, name: investigationRow.leadName ?? '' } : null,
        method: investigationRow.investigation.method,
        summary: investigationRow.investigation.summary,
        startedAt: iso(investigationRow.investigation.startedAt),
        completedAt: iso(investigationRow.investigation.completedAt),
      }
    : null
  const actions = actionRows.map((action) => toAction(action))
  const manage = hasRole(user.role, 'supervisor')

  return {
    ...toIncident(row),
    investigation,
    rootCauses: causes.map((cause): RootCause => ({ id: cause.id, category: cause.category, description: cause.description, whys: cause.whys })),
    actions,
    attachments: files.map(({ file, uploaderName }) => toAttachment(file, uploaderName)),
    transitions: availableTransitions(row.incident.status, user.role, {
      severity: row.incident.severity,
      rootCauseCount: causes.length,
      actionStatuses: actions.map((action) => action.status),
    }),
    can: { edit: manage, manageInvestigation: manage, manageActions: manage },
  }
}

/** Records an event on an incident's timeline. */
export function auditIncident(db: Db, user: SessionUser | null, organizationId: string, incidentId: string, action: string, changes?: Record<string, unknown>) {
  return audit(db, { organizationId, actorId: user?.id ?? null, entityType: 'incident', entityId: incidentId, action, changes })
}

/** Throws 400 unless the user is active in the organization. */
export async function assertActiveUser(db: Db, organizationId: string, userId: string) {
  const [user] = await db
    .select({ id: users.id })
    .from(users)
    .where(and(eq(users.id, userId), eq(users.organizationId, organizationId), eq(users.active, true)))
  if (!user) throw fail(400, 'Unknown or inactive user')
}