import { Injectable } from '@nestjs/common';
import { Prisma } from '../../../generated/prisma';
import { PrismaService } from '../../prisma/prisma.service';

export interface VoiceCaptureStats {
  byStatus: Record<string, number>;
  byError: Record<string, number>;
  tokens: { input: number; output: number };
  byModel: Record<string, number>;
}

interface CountRow {
  key: string;
  count: number;
}

interface TokenRow {
  input: bigint | number;
  output: bigint | number;
}

function toRecord(rows: readonly CountRow[]): Record<string, number> {
  return Object.fromEntries(rows.map((row) => [row.key, Number(row.count)]));
}

/**
 * Counters of the last seven days for the system area: per status, per error
 * code, per model and the token sums. Aggregates only - no user, no capture
 * id, no content. The window runs on the database clock.
 */
@Injectable()
export class VoiceCapturesStatsService {
  constructor(private readonly prisma: PrismaService) {}

  async stats(): Promise<VoiceCaptureStats> {
    const since = Prisma.sql`"createdAt" > (now() AT TIME ZONE 'UTC') - interval '7 days'`;
    const [byStatus, byError, byModel, tokens] = await Promise.all([
      this.prisma.$queryRaw<CountRow[]>(Prisma.sql`
        SELECT "status"::text AS "key", count(*)::int AS "count"
        FROM "VoiceCapture" WHERE ${since} GROUP BY "status"`),
      this.prisma.$queryRaw<CountRow[]>(Prisma.sql`
        SELECT "lastErrorCode" AS "key", count(*)::int AS "count"
        FROM "VoiceCapture"
        WHERE ${since} AND "lastErrorCode" IS NOT NULL
        GROUP BY "lastErrorCode"`),
      this.prisma.$queryRaw<CountRow[]>(Prisma.sql`
        SELECT "model" AS "key", count(*)::int AS "count"
        FROM "VoiceCapture"
        WHERE ${since} AND "model" IS NOT NULL
        GROUP BY "model"`),
      this.prisma.$queryRaw<TokenRow[]>(Prisma.sql`
        SELECT COALESCE(sum("inputTokens"), 0) AS "input",
               COALESCE(sum("outputTokens"), 0) AS "output"
        FROM "VoiceCapture" WHERE ${since}`),
    ]);
    return {
      byStatus: toRecord(byStatus),
      byError: toRecord(byError),
      tokens: {
        input: Number(tokens[0]?.input ?? 0),
        output: Number(tokens[0]?.output ?? 0),
      },
      byModel: toRecord(byModel),
    };
  }
}