import { Injectable, NotFoundException } from '@nestjs/common';
import { PrismaService } from '../prisma/prisma.service';
import { AuditLogService } from '../audit/audit-log.service';
import { NotificationsService } from '../notifications/notifications.service';
import { WebhooksService } from '../webhooks/webhooks.service';
import {
  AutomationRule,
  AutomationTriggerType,
  Colony,
  Inspection,
  Feeding,
  Prisma,
  StockItem,
  SwarmControlCheck,
  TaskRelatedType,
  Treatment,
  VarroaMeasurement,
} from '../../generated/prisma';
import { UpdateAutomationRuleDto } from './dto/update-automation-rule.dto';
import { formatGeneratedNumber } from './number-format';

interface RuleDefaults {
  config: Record<string, unknown>;
  actionTemplate: string;
  /** Rules without a sensible built-in setting start switched off. */
  active?: boolean;
}

const DEFAULT_RULES: Record<AutomationTriggerType, RuleDefaults> = {
  QUEENLESS_NO_EGGS: {
    config: {},
    actionTemplate:
      'Kontrolle empfohlen: Königin nicht gesehen und keine Stifte vorhanden.',
  },
  VARROA_THRESHOLD: {
    config: { thresholdMitesPerDay: 10 },
    actionTemplate: 'Behandlung prüfen: Varroa-Schwellenwert überschritten.',
  },
  FEED_STATUS_CRITICAL: {
    config: {},
    actionTemplate: 'Fütterung erforderlich: Futterstatus kritisch.',
  },
  SWARM_MOOD_HIGH: {
    config: {},
    actionTemplate:
      'Schwarmkontrolle dringend: hohe Schwarmstimmung festgestellt.',
  },
  COLONY_HEALTH_CRITICAL: {
    config: {},
    actionTemplate: 'Kontrolle erforderlich: Gesundheitsstatus kritisch.',
  },
  STOCK_ITEM_LOW: {
    config: {},
    actionTemplate: 'Nachbestellung prüfen: Lagerartikel unter Mindestbestand.',
  },
  // Not task-generating rules like the ones above - `active` here toggles
  // whether HoneyBatchesService/BottlingService auto-fill the batch/lot
  // number from `config.format` instead of requiring manual entry.
  HONEY_BATCH_NUMBER_FORMAT: {
    config: { format: 'WH-{YYYY}-{SEQ:4}' },
    actionTemplate: '',
  },
  BOTTLING_LOT_NUMBER_FORMAT: {
    config: { format: 'WH-{YYYY}-{SEQ:4}' },
    actionTemplate: '',
  },
  // Follow-up checks: how many days after a treatment or feeding a check
  // makes sense depends on the product and the season, so there is no
  // built-in interval - the beekeeper switches the rule on and sets
  // config.dueInDays.
  TREATMENT_FOLLOW_UP: {
    config: {},
    actionTemplate: 'Behandlungserfolg kontrollieren',
    active: false,
  },
  FEEDING_FOLLOW_UP: {
    config: {},
    actionTemplate: 'Futterabnahme und Futtervorrat kontrollieren',
    active: false,
  },
};

/**
 * Optional per-rule follow-up interval (config.dueInDays). There is no
 * built-in default: how soon a queenless colony or a high mite fall needs a
 * look depends on season and practice, so the rule stays date-less unless the
 * beekeeper configures one.
 */
function formatDay(date: Date): string {
  return date.toLocaleDateString('de-DE', {
    day: '2-digit',
    month: '2-digit',
    year: 'numeric',
    timeZone: 'UTC',
  });
}

function dueDateFromConfig(
  dueInDays: unknown,
  baseDate: Date = new Date(),
): Date | undefined {
  if (
    typeof dueInDays !== 'number' ||
    !Number.isInteger(dueInDays) ||
    dueInDays < 0 ||
    dueInDays > 365
  ) {
    return undefined;
  }
  const due = new Date(baseDate);
  due.setUTCHours(0, 0, 0, 0);
  due.setUTCDate(due.getUTCDate() + dueInDays);
  return due;
}

@Injectable()
export class AutomationService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly auditLog: AuditLogService,
    private readonly notifications: NotificationsService,
    private readonly webhooks: WebhooksService,
  ) {}

  private async ensureDefaults(): Promise<void> {
    for (const triggerType of Object.keys(
      DEFAULT_RULES,
    ) as AutomationTriggerType[]) {
      const defaults = DEFAULT_RULES[triggerType];
      await this.prisma.automationRule.upsert({
        where: { triggerType },
        update: {},
        create: {
          triggerType,
          active: defaults.active ?? true,
          config: defaults.config as Prisma.InputJsonValue,
          actionTemplate: defaults.actionTemplate,
        },
      });
    }
  }

  async findAll(): Promise<AutomationRule[]> {
    await this.ensureDefaults();
    return this.prisma.automationRule.findMany({
      orderBy: { triggerType: 'asc' },
    });
  }

  async findById(id: string): Promise<AutomationRule> {
    const rule = await this.prisma.automationRule.findUnique({
      where: { id },
    });
    if (!rule) {
      throw new NotFoundException('Automation rule not found');
    }
    return rule;
  }

  async update(
    id: string,
    dto: UpdateAutomationRuleDto,
    actingUserId: string,
  ): Promise<AutomationRule> {
    const before = await this.findById(id);
    const rule = await this.prisma.automationRule.update({
      where: { id },
      data: {
        ...dto,
        config: dto.config as Prisma.InputJsonValue | undefined,
      },
    });
    await this.auditLog.record({
      entityType: 'AutomationRule',
      entityId: id,
      action: 'UPDATE',
      userId: actingUserId,
      beforeData: before,
      afterData: rule,
    });
    return rule;
  }

  async evaluateInspection(inspection: Inspection): Promise<void> {
    await this.ensureDefaults();
    const rules = await this.prisma.automationRule.findMany({
      where: {
        triggerType: { in: ['QUEENLESS_NO_EGGS', 'FEED_STATUS_CRITICAL'] },
        active: true,
      },
    });
    const ruleByType = new Map(rules.map((rule) => [rule.triggerType, rule]));

    const queenlessRule = ruleByType.get('QUEENLESS_NO_EGGS');
    if (
      queenlessRule &&
      inspection.queenSeen === false &&
      inspection.eggsPresent === false
    ) {
      await this.triggerAction(
        queenlessRule,
        'COLONY',
        inspection.colonyId,
        inspection.id,
      );
    }

    const feedRule = ruleByType.get('FEED_STATUS_CRITICAL');
    if (feedRule && inspection.feedStatus?.toLowerCase() === 'kritisch') {
      await this.triggerAction(
        feedRule,
        'COLONY',
        inspection.colonyId,
        inspection.id,
      );
    }
  }

  async evaluateVarroaMeasurement(
    measurement: VarroaMeasurement,
  ): Promise<void> {
    await this.ensureDefaults();
    const rule = await this.prisma.automationRule.findUnique({
      where: { triggerType: 'VARROA_THRESHOLD' },
    });
    if (!rule || !rule.active) {
      return;
    }
    // The threshold is a natural mite fall rate (mites per day). Only that
    // method yields a value in this unit - a mite count from a sugar roll or
    // wash is per bee sample and would be compared against the wrong scale,
    // as would a raw board count without the number of days it covered.
    if (measurement.method !== 'NATURAL_MITE_FALL') {
      return;
    }
    const config = rule.config as { thresholdMitesPerDay?: number } | null;
    const threshold = config?.thresholdMitesPerDay ?? 10;
    const value = measurement.calculatedValue;
    if (value !== null && value >= threshold) {
      await this.triggerAction(rule, 'COLONY', measurement.colonyId);
    }
  }

  async evaluateSwarmControlCheck(check: SwarmControlCheck): Promise<void> {
    await this.ensureDefaults();
    const rule = await this.prisma.automationRule.findUnique({
      where: { triggerType: 'SWARM_MOOD_HIGH' },
    });
    if (!rule || !rule.active) {
      return;
    }
    if (check.swarmMood === 'HIGH') {
      await this.triggerAction(rule, 'COLONY', check.colonyId);
    }
  }

  /** Fires only on the transition into CRITICAL, not on every edit while already critical. */
  async evaluateColonyHealth(before: Colony, after: Colony): Promise<void> {
    await this.ensureDefaults();
    if (
      after.healthStatus !== 'CRITICAL' ||
      before.healthStatus === 'CRITICAL'
    ) {
      return;
    }
    const rule = await this.prisma.automationRule.findUnique({
      where: { triggerType: 'COLONY_HEALTH_CRITICAL' },
    });
    if (!rule || !rule.active) {
      return;
    }
    await this.triggerAction(rule, 'COLONY', after.id);
  }

  async evaluateStockItem(item: StockItem): Promise<void> {
    await this.ensureDefaults();
    if (item.minThreshold === null || item.quantity >= item.minThreshold) {
      return;
    }
    const rule = await this.prisma.automationRule.findUnique({
      where: { triggerType: 'STOCK_ITEM_LOW' },
    });
    if (!rule || !rule.active) {
      return;
    }
    await this.triggerAction(rule, 'STORAGE', item.id);
  }

  async evaluateTreatment(treatment: Treatment): Promise<void> {
    await this.evaluateFollowUp(
      'TREATMENT_FOLLOW_UP',
      treatment.colonyId,
      treatment.endDate ?? treatment.date,
      `Nach Behandlung mit ${treatment.product} am ${formatDay(treatment.endDate ?? treatment.date)}.`,
    );
  }

  async evaluateFeeding(feeding: Feeding): Promise<void> {
    await this.evaluateFollowUp(
      'FEEDING_FOLLOW_UP',
      feeding.colonyId,
      feeding.date,
      `Nach Fütterung (${feeding.amount} ${feeding.unit}) am ${formatDay(feeding.date)}.`,
    );
  }

  /** A check counted from the measure's own date, not from today. */
  private async evaluateFollowUp(
    triggerType: 'TREATMENT_FOLLOW_UP' | 'FEEDING_FOLLOW_UP',
    colonyId: string,
    measureDate: Date,
    description: string,
  ): Promise<void> {
    await this.ensureDefaults();
    const rule = await this.prisma.automationRule.findUnique({
      where: { triggerType },
    });
    if (!rule || !rule.active) {
      return;
    }
    await this.triggerAction(rule, 'COLONY', colonyId, undefined, {
      baseDate: measureDate,
      description,
    });
  }

  // Returns null (never throws) when the rule is inactive or has no format
  // configured, so the caller can fall back to requiring manual entry.
  async generateNumber(
    triggerType: 'HONEY_BATCH_NUMBER_FORMAT' | 'BOTTLING_LOT_NUMBER_FORMAT',
  ): Promise<string | null> {
    await this.ensureDefaults();
    const rule = await this.prisma.automationRule.findUnique({
      where: { triggerType },
    });
    if (!rule || !rule.active) {
      return null;
    }
    const config = rule.config as { format?: string } | null;
    const format = config?.format;
    if (!format) {
      return null;
    }
    // Atomic `SET sequenceValue = sequenceValue + 1` - safe under concurrent
    // batch/bottling creation, no explicit transaction/lock needed.
    const updated = await this.prisma.automationRule.update({
      where: { triggerType },
      data: { sequenceValue: { increment: 1 } },
      select: { sequenceValue: true },
    });
    return formatGeneratedNumber(format, updated.sequenceValue, new Date());
  }

  async resetSequence(
    id: string,
    actingUserId: string,
  ): Promise<AutomationRule> {
    const before = await this.findById(id);
    const rule = await this.prisma.automationRule.update({
      where: { id },
      data: { sequenceValue: 0 },
    });
    await this.auditLog.record({
      entityType: 'AutomationRule',
      entityId: id,
      action: 'UPDATE',
      userId: actingUserId,
      beforeData: before,
      afterData: rule,
    });
    return rule;
  }

  /**
   * Leaves a suggestion task (never a record of work done) plus a warning.
   *
   * At most one open task per rule and object: while the reorder task for a
   * stock item or the check task for a colony is still open, further triggers
   * (the next removal below minimum, a second high varroa count) add nothing.
   * Repeating the same alarm would only bury the one task that matters.
   */
  private async triggerAction(
    rule: AutomationRule,
    relatedType: TaskRelatedType,
    relatedId: string,
    sourceInspectionId?: string,
    options: { baseDate?: Date; description?: string } = {},
  ): Promise<void> {
    const alreadyOpen = await this.prisma.task.findFirst({
      where: {
        sourceAutomationTrigger: rule.triggerType,
        relatedType,
        relatedId,
        status: { in: ['OPEN', 'IN_PROGRESS'] },
      },
      select: { id: true },
    });
    if (alreadyOpen) {
      return;
    }

    const title = rule.actionTemplate ?? 'Automatisierte Aufgabe';
    const config = rule.config as { dueInDays?: unknown } | null;
    const task = await this.prisma.task.create({
      data: {
        title,
        priority: 'HIGH',
        relatedType,
        relatedId,
        sourceInspectionId,
        sourceAutomationTrigger: rule.triggerType,
        description: options.description,
        dueDate: dueDateFromConfig(config?.dueInDays, options.baseDate),
      },
    });
    await this.webhooks.dispatch('task.created', task);
    await this.notifications.record({
      priority: 'WARNUNG',
      message: title,
      relatedType,
      relatedId,
    });
    await this.auditLog.record({
      entityType: 'AutomationRule',
      entityId: rule.id,
      action: 'CREATE',
      afterData: {
        taskId: task.id,
        relatedType,
        relatedId,
        triggerType: rule.triggerType,
      },
    });
  }
}