import { BadRequestException } from "@nestjs/common";
import { ExpenseResponse } from "../types and interfaces/expenses.types.interfaces";
import { Prisma } from "@prisma/client";

//uppercase and trim for validation
export function normalizeType(type: string): string {
    return (type ?? '').trim().toUpperCase();
};

//required comment after trim
export function assertAndTrimComment(comment: string): string {
    const cmt = (comment ?? '').trim();
    if(cmt.length === 0) {
        throw new BadRequestException('A comment is required');
    }
    return cmt;
};

//rounding $ to 2 decimals
export function roundMoney2(num: number): number {
    return Math.round((num + Number.EPSILON) * 100)/ 100;
};

export function computeMileageAmount(km: number, modifier: number): number {
    if(km < 0)       throw new BadRequestException('mileage must be positive');
    if(modifier < 0) throw new BadRequestException('modifier must be positive');
    return roundMoney2(km * modifier);
};

//compat. types with Prisma.Decimal. work around Prisma import in utils.
export type DecimalLike = 
    | number
    | string
    | { toNumber?: () => number }
    | { toString?: () => string };


//safe conversion to number
export function toNumberSafe(value: DecimalLike): number {
    if(typeof value === 'number') return value;
    if(value && typeof (value as any).toNumber === 'function') return (value as any).toNumber();
    return Number(
        typeof (value as any)?.toString === 'function'
        ? (value as any).toString()
        : value,
    );
}

export const parseAttachmentId = (value: unknown): number | null => {
    if (value == null) {
        return null;
    }

    if (typeof value === 'number') {
        if (!Number.isInteger(value) || value <= 0) {
        throw new BadRequestException('Invalid attachment id');
        }
        return value;
    }

    if (typeof value === 'string') {

        const trimmed = value.trim();
        if (!trimmed.length) return null;      
        if (!/^\d+$/.test(trimmed)) throw new BadRequestException('Invalid attachment id');
        
        const parsed = Number(trimmed);
        if (parsed <= 0) throw new BadRequestException('Invalid attachment id');

        return parsed;
    }
    throw new BadRequestException('Invalid attachment id');
};


//map of a row for DayExpenseResponse
export function mapDbExpenseToDayResponse(row: {
    date:        Date;
    amount:      Prisma.Decimal | number | string | null;
    mileage?:    Prisma.Decimal | number | string | null;
    comment:     string;
    is_approved: boolean;
    bank_code?:  { type?: string |  null } | null;
}): ExpenseResponse {
    const yyyyMmDd = row.date.toISOString().slice(0,10);
    const toNum = (value: any)=> (value == null ? 0 : Number(value));
    return {
        date:        yyyyMmDd,
        type:        normalizeType(row.bank_code?.type ?? 'UNKNOWN'),
        amount:      toNum(row.amount),
        comment:     row.comment,
        is_approved: row.is_approved,
        ...(row.mileage !== null ? { mileage: toNum(row.mileage) }: {}),
    };
}
  
  export const computeAmountDecimal = ( 
    type: string, 
    payload: { 
      amount?:  number; 
      mileage?: number;
    },
    modifier: number,    
  ): Prisma.Decimal => {
    if(type === 'MILEAGE') {
      const km = payload.mileage ?? 0;
      const amountNumber = computeMileageAmount(km, modifier);
      return new Prisma.Decimal(amountNumber);
    }
    return new Prisma.Decimal(payload.amount!);
  };