import { Injectable } from '@nestjs/common';
import { BaseRepository } from '@edr/api-common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import type { QueryDeepPartialEntity } from 'typeorm/query-builder/QueryPartialEntity';

import { AuditLog } from './entities/audit-log.entity';
import type { AuditReferenceSource } from './audit-reference.registry';

export interface AuditLogQuery {
  type?: string;
  userId?: string;
  method?: string;
  isSuccess?: boolean;
  resourceId?: string;
  reference?: string;
  userName?: string;
  title?: string;
  q?: string;
  from?: Date;
  to?: Date;
  skip: number;
  take: number;
}

@Injectable()
export class AuditLogRepository extends BaseRepository<AuditLog> {
  constructor(
    @InjectRepository(AuditLog)
    private readonly auditLogRepository: Repository<AuditLog>,
  ) {
    super(auditLogRepository);
  }

  /**
   * Insert one audit row.
   *
   * `insert` rather than `save`: save would issue a SELECT first to decide
   * between insert and update, which is wasted work for a table that is only
   * ever appended to.
   */
  async record(entry: Partial<AuditLog>): Promise<void> {
    await this.auditLogRepository.insert(
      entry as QueryDeepPartialEntity<AuditLog>,
    );
  }

  /**
   * Resolve the human identifier for one entity row (`WHERE id = $1`).
   *
   * `source` comes from the static `AUDIT_REFERENCE_SOURCES` registry — never
   * from user input — so interpolating its table/column is safe; the id is
   * bound as a parameter. Returns null when the row doesn't exist or the
   * identifier column is empty.
   */
  async lookupReference(
    source: AuditReferenceSource,
    id: string,
  ): Promise<string | null> {
    const rows = await this.auditLogRepository.manager.query<
      { reference: string | null }[]
    >(
      `SELECT ${source.column}::varchar AS reference FROM ${source.table} WHERE id = $1::uuid`,
      [id],
    );
    return rows[0]?.reference || null;
  }

  /**
   * Paginated, filtered read. Newest first — every index on this table is
   * ordered `created_at DESC` to match.
   *
   * Query builder rather than `findAndCount`: `q` needs an OR across four
   * columns, and `reference` needs the `upper(...) LIKE` shape that matches
   * the expression index — neither fits `FindOptionsWhere`.
   */
  async search(query: AuditLogQuery): Promise<[AuditLog[], number]> {
    const qb = this.auditLogRepository.createQueryBuilder('audit_log');

    if (query.type) qb.andWhere('audit_log.type = :type', { type: query.type });
    if (query.userId) qb.andWhere('audit_log.user_id = :userId', { userId: query.userId });
    if (query.method) qb.andWhere('audit_log.method = :method', { method: query.method });
    if (query.resourceId) {
      qb.andWhere('audit_log.resource_id = :resourceId', { resourceId: query.resourceId });
    }
    if (query.isSuccess !== undefined) {
      qb.andWhere('audit_log.is_success = :isSuccess', { isSuccess: query.isSuccess });
    }

    // Case-insensitive prefix match, shaped to hit idx_audit_logs_reference_upper.
    // The explicit <> '' repeats the index's partial predicate — without it the
    // planner cannot prove the partial index applies and falls back to a scan.
    if (query.reference) {
      qb.andWhere("audit_log.reference <> ''").andWhere(
        "upper(audit_log.reference) LIKE upper(:reference) || '%'",
        { reference: escapeLike(query.reference) },
      );
    }
    if (query.userName) {
      qb.andWhere('audit_log.user_name ILIKE :userName', {
        userName: `%${escapeLike(query.userName)}%`,
      });
    }
    if (query.title) {
      qb.andWhere('audit_log.title ILIKE :title', {
        title: `%${escapeLike(query.title)}%`,
      });
    }

    // One search box across the columns staff actually search by.
    // ponytail: ILIKE %…% scans the time-bounded window; add pg_trgm GIN
    // indexes if the table grows past a few million rows.
    if (query.q) {
      const q = `%${escapeLike(query.q)}%`;
      qb.andWhere(
        `(audit_log.reference ILIKE :q
          OR audit_log.resource_id ILIKE :q
          OR audit_log.user_name ILIKE :q
          OR audit_log.title ILIKE :q)`,
        { q },
      );
    }

    // Date range: either bound may be supplied alone.
    if (query.from) qb.andWhere('audit_log.created_at >= :from', { from: query.from });
    if (query.to) qb.andWhere('audit_log.created_at <= :to', { to: query.to });

    return qb
      .orderBy('audit_log.created_at', 'DESC')
      .skip(query.skip)
      .take(query.take)
      .getManyAndCount();
  }

  /** Distinct entity types present, for populating a filter dropdown. */
  async distinctTypes(): Promise<string[]> {
    const rows = await this.auditLogRepository
      .createQueryBuilder('audit_log')
      .select('DISTINCT audit_log.type', 'type')
      .orderBy('audit_log.type', 'ASC')
      .getRawMany<{ type: string }>();

    return rows.map((row) => row.type);
  }

  /** Distinct action titles present, for the action filter dropdown. */
  async distinctTitles(): Promise<string[]> {
    const rows = await this.auditLogRepository
      .createQueryBuilder('audit_log')
      .select('DISTINCT audit_log.title', 'title')
      .orderBy('audit_log.title', 'ASC')
      .getRawMany<{ title: string }>();

    return rows.map((row) => row.title);
  }
}

/** Escape LIKE wildcards so a literal `%`/`_` in the search text stays literal. */
function escapeLike(value: string): string {
  return value.replace(/[\\%_]/g, (ch) => `\\${ch}`);
}