import { BadRequestException, Inject, Injectable } from '@nestjs/common';
import {
  QUALITY_REPOSITORY,
  type ActiveQualityRule,
  type CreateQualityRuleInput,
  type QualityRepository,
  type QualityRuleStatus,
  type QualityRuleSummary,
  type UpdateQualityRuleInput
} from './quality.repository.js';
import { stableSamplingDecision } from './sampling.js';

interface QualityRuleBody {
  name?: unknown;
  customerId?: unknown;
  lineGroupId?: unknown;
  ratio?: unknown;
  status?: unknown;
  effectiveAt?: unknown;
  expiresAt?: unknown;
}

export interface RecordingSamplingContext {
  recordingId: string;
  customerId: string | null;
  lineGroupId: string | null;
}

export interface RecordingSamplingMatch {
  ruleId: string;
  ruleName: string;
  ratio: string;
  score: number;
  selected: boolean;
}

@Injectable()
export class QualityService {
  constructor(@Inject(QUALITY_REPOSITORY) private readonly quality: QualityRepository) {}

  listRules(): Promise<QualityRuleSummary[]> {
    return this.quality.listRules();
  }

  getRule(ruleId: string): Promise<QualityRuleSummary> {
    return this.quality.getRule(ruleId);
  }

  createRule(body: QualityRuleBody, actorId?: string): Promise<QualityRuleSummary> {
    const effectiveAt = body.effectiveAt === undefined ? undefined : this.date(body.effectiveAt, 'effectiveAt');
    const expiresAt = body.expiresAt === undefined ? undefined : this.nullableDate(body.expiresAt, 'expiresAt');
    this.ensureDateRange(effectiveAt, expiresAt);
    const input: CreateQualityRuleInput = {
      name: this.limitedString(body.name, 'name', 120),
      customerId: this.nullableId(body.customerId, 'customerId', 32),
      lineGroupId: this.nullableId(body.lineGroupId, 'lineGroupId', 32),
      ratio: this.ratio(body.ratio),
      status: body.status === undefined ? 'ENABLED' : this.status(body.status),
      effectiveAt,
      expiresAt,
      actorId
    };
    return this.quality.createRule(input);
  }

  updateRule(ruleId: string, body: QualityRuleBody, actorId?: string): Promise<QualityRuleSummary> {
    const effectiveAt = body.effectiveAt === undefined ? undefined : this.date(body.effectiveAt, 'effectiveAt');
    const expiresAt = body.expiresAt === undefined ? undefined : this.nullableDate(body.expiresAt, 'expiresAt');
    this.ensureDateRange(effectiveAt, expiresAt);
    const input: UpdateQualityRuleInput = {
      name: body.name === undefined ? undefined : this.limitedString(body.name, 'name', 120),
      customerId: body.customerId === undefined ? undefined : this.nullableId(body.customerId, 'customerId', 32),
      lineGroupId: body.lineGroupId === undefined ? undefined : this.nullableId(body.lineGroupId, 'lineGroupId', 32),
      ratio: body.ratio === undefined ? undefined : this.ratio(body.ratio),
      status: body.status === undefined ? undefined : this.status(body.status),
      effectiveAt,
      expiresAt,
      actorId
    };
    return this.quality.updateRule(ruleId, input);
  }

  enableRule(ruleId: string, actorId?: string): Promise<QualityRuleSummary> {
    return this.quality.setRuleStatus(ruleId, 'ENABLED', actorId);
  }

  disableRule(ruleId: string, actorId?: string): Promise<QualityRuleSummary> {
    return this.quality.setRuleStatus(ruleId, 'DISABLED', actorId);
  }

  deleteRule(ruleId: string, actorId?: string): Promise<QualityRuleSummary> {
    return this.quality.softDeleteRule(ruleId, actorId);
  }

  async samplingFor(context: RecordingSamplingContext, now = new Date()): Promise<{ selected: boolean; matches: RecordingSamplingMatch[] }> {
    const rules = await this.quality.listActiveRules(now);
    const matches = this.matchRules(rules, context).map((rule) => {
      const decision = stableSamplingDecision(rule.id, context.recordingId, rule.ratio);
      return {
        ruleId: rule.id,
        ruleName: rule.name,
        ratio: rule.ratio,
        score: decision.score,
        selected: decision.selected
      };
    });
    return {
      selected: matches.some((match) => match.selected),
      matches
    };
  }

  private matchRules(rules: ActiveQualityRule[], context: RecordingSamplingContext): ActiveQualityRule[] {
    return rules.filter((rule) => {
      const customerMatches = !rule.customerId || rule.customerId === context.customerId;
      const lineGroupMatches = !rule.lineGroupId || rule.lineGroupId === context.lineGroupId;
      return customerMatches && lineGroupMatches;
    });
  }

  private limitedString(value: unknown, field: string, maxLength: number): string {
    if (typeof value !== 'string' || value.trim().length === 0) {
      throw new BadRequestException({ code: 'VALIDATION_ERROR', message: `${field} is required.` });
    }
    const trimmed = value.trim();
    if (trimmed.length > maxLength) {
      throw new BadRequestException({ code: 'VALIDATION_ERROR', message: `${field} is too long.` });
    }
    return trimmed;
  }

  private nullableId(value: unknown, field: string, maxLength: number): string | null {
    if (value === undefined || value === null || value === '') {
      return null;
    }
    return this.limitedString(value, field, maxLength);
  }

  private ratio(value: unknown): string {
    const raw = typeof value === 'number' ? value.toString() : typeof value === 'string' ? value.trim() : '';
    if (!/^(?:100(?:\.0{1,2})?|\d{1,2}(?:\.\d{1,2})?)$/.test(raw)) {
      throw new BadRequestException({ code: 'QUALITY_RATIO_INVALID', message: 'ratio must be from 0 to 100 with up to 2 decimals.' });
    }
    const numeric = Number.parseFloat(raw);
    if (!Number.isFinite(numeric) || numeric < 0 || numeric > 100) {
      throw new BadRequestException({ code: 'QUALITY_RATIO_INVALID', message: 'ratio must be from 0 to 100 with up to 2 decimals.' });
    }
    const [integerPart, fractionPart = ''] = raw.split('.');
    return `${integerPart}.${fractionPart.padEnd(2, '0')}`;
  }

  private status(value: unknown): QualityRuleStatus {
    if (value !== 'ENABLED' && value !== 'DISABLED') {
      throw new BadRequestException({ code: 'STATUS_INVALID', message: 'status is invalid.' });
    }
    return value;
  }

  private date(value: unknown, field: string): Date {
    if (typeof value !== 'string') {
      throw new BadRequestException({ code: 'DATE_INVALID', message: `${field} must be an ISO date string.` });
    }
    const parsed = new Date(value);
    if (Number.isNaN(parsed.getTime())) {
      throw new BadRequestException({ code: 'DATE_INVALID', message: `${field} must be an ISO date string.` });
    }
    return parsed;
  }

  private nullableDate(value: unknown, field: string): Date | null {
    if (value === null || value === '') {
      return null;
    }
    return this.date(value, field);
  }

  private ensureDateRange(effectiveAt?: Date, expiresAt?: Date | null): void {
    if (effectiveAt && expiresAt && expiresAt <= effectiveAt) {
      throw new BadRequestException({ code: 'QUALITY_RULE_DATE_RANGE_INVALID', message: 'expiresAt must be after effectiveAt.' });
    }
  }
}