import { applyDecorators } from '@nestjs/common';
import { ApiProperty } from '@nestjs/swagger';
import { Type } from 'class-transformer';
import {
  ArrayMaxSize,
  ArrayMinSize,
  ArrayUnique,
  IsArray,
  IsNotEmpty,
  IsString,
  ValidateNested,
} from 'class-validator';
import { BULK_MAX_COLONIES } from './bulk-limits';

const DUPLICATE_COLONY_MESSAGE = '$property enthält ein Volk doppelt';

// The size rule every bulk list shares: at least one colony, at most
// BULK_MAX_COLONIES.
function bulkListSize(): PropertyDecorator[] {
  return [
    IsArray({ message: '$property muss eine Liste sein' }),
    ArrayMinSize(1, { message: '$property braucht mindestens ein Volk' }),
    ArrayMaxSize(BULK_MAX_COLONIES, {
      message: `$property darf höchstens ${BULK_MAX_COLONIES} Völker enthalten`,
    }),
  ];
}

// The rule for one colony id - in colonyIds (each) and in every entry - so an
// empty id is invalid input on both paths, never an "unknown colony".
function colonyIdChecks(each: boolean): PropertyDecorator[] {
  return [
    IsString({ each, message: '$property enthält eine ungültige Volk-ID' }),
    IsNotEmpty({ each, message: '$property enthält eine leere Volk-ID' }),
  ];
}

/** `colonyIds` of a bulk entry with shared values: distinct, non-empty ids. */
export function IsBulkColonyIds(): PropertyDecorator {
  return applyDecorators(
    ApiProperty({
      type: [String],
      minItems: 1,
      maxItems: BULK_MAX_COLONIES,
      uniqueItems: true,
      description: `Die Völker, für die derselbe Eintrag gilt (1 bis ${BULK_MAX_COLONIES}, jedes nur einmal)`,
    }),
    ...bulkListSize(),
    ArrayUnique({ message: DUPLICATE_COLONY_MESSAGE }),
    ...colonyIdChecks(true),
  );
}

/** `colonyId` of one entry in `entries`: a non-empty id. */
export function IsBulkEntryColonyId(): PropertyDecorator {
  return applyDecorators(
    ApiProperty({ description: 'Das Volk dieses Eintrags' }),
    ...colonyIdChecks(false),
  );
}

/**
 * `entries` of a bulk entry with one value set per colony: each entry is
 * validated as its class, and each colony appears once.
 */
export function IsBulkEntries(
  entryType: new () => { colonyId: string },
): PropertyDecorator {
  return applyDecorators(
    ApiProperty({
      type: [entryType],
      minItems: 1,
      maxItems: BULK_MAX_COLONIES,
      description: `Ein Eintrag je Volk (1 bis ${BULK_MAX_COLONIES}, jedes Volk nur einmal)`,
    }),
    ...bulkListSize(),
    // class-validator skips null entries before calling the selector.
    ArrayUnique((entry: { colonyId?: unknown }) => entry.colonyId, {
      message: DUPLICATE_COLONY_MESSAGE,
    }),
    ValidateNested({ each: true }),
    Type(() => entryType),
  );
}