const { AppError } = require("../utils/AppError");
const { compactDateString } = require("../utils/date");

const DOCUMENT_TYPE_ALIASES = {
  expense: "reimbursement",
};

const DOCUMENT_TYPE_CONFIG = {
  reimbursement: {
    defaultCategoryCode: "reimbursement_general",
    preferLegacySequence: true,
    fallback: {
      prefix: "BX",
      dateFormat: "YYYYMMDD",
      separator: "-",
      numberLength: 4,
      resetPeriod: "none",
    },
  },
  leave: {
    defaultCategoryCode: "leave_request",
    preferLegacySequence: false,
    fallback: {
      prefix: "JQ",
      dateFormat: "YYYYMMDD",
      separator: "-",
      numberLength: 4,
      resetPeriod: "yearly",
    },
  },
  purchase_request: {
    defaultCategoryCode: "PR_STANDARD",
    preferLegacySequence: false,
    fallback: {
      prefix: "CG",
      dateFormat: "YYYYMMDD",
      separator: "-",
      numberLength: 4,
      resetPeriod: "yearly",
    },
  },
  asset_card: {
    defaultCategoryCode: "ASSET_CARD_DEFAULT",
    preferLegacySequence: false,
    fallback: {
      prefix: "ZC",
      dateFormat: "YYYYMMDD",
      separator: "-",
      numberLength: 4,
      resetPeriod: "yearly",
    },
  },
  general: {
    defaultCategoryCode: "general_record",
    preferLegacySequence: false,
    fallback: {
      prefix: "GEN",
      dateFormat: "YYYYMMDD",
      separator: "-",
      numberLength: 4,
      resetPeriod: "yearly",
    },
  },
};

function buildValidationError(details, statusCode = 400) {
  return new AppError({
    code: "VALID_001",
    message: "参数校验失败",
    statusCode,
    details,
  });
}

function normalizeDocumentType(documentType) {
  const rawValue = String(documentType ?? "").trim().toLowerCase();
  const normalized = DOCUMENT_TYPE_ALIASES[rawValue] ?? rawValue;
  if (!DOCUMENT_TYPE_CONFIG[normalized]) {
    throw buildValidationError({ documentType: "unsupported_document_type" }, 409);
  }
  return normalized;
}

function mapSequenceRecord(record) {
  if (!record) {
    return null;
  }

  return {
    documentType: record.document_type,
    prefix: record.prefix,
    dateFormat: record.date_format,
    separator: record.separator,
    numberLength: record.number_length,
    resetPeriod: record.reset_period,
    currentNumber: record.current_number,
    lastResetDate: record.last_reset_date?.toISOString?.()?.slice(0, 10) ?? null,
    updatedAt: record.updated_at?.toISOString?.() ?? null,
    updatedBy: record.updated_by ?? null,
  };
}

function buildConfigFromFallback(documentType) {
  const fallback = DOCUMENT_TYPE_CONFIG[documentType].fallback;
  return {
    exists: false,
    source: "fallback",
    documentType,
    documentCategoryCode: null,
    currentNumber: 0,
    lastResetDate: null,
    updatedAt: null,
    updatedBy: null,
    ...fallback,
  };
}

function buildConfigFromCategory(documentType, category, sequenceRecord) {
  const fallback = DOCUMENT_TYPE_CONFIG[documentType].fallback;
  const mappedSequence = mapSequenceRecord(sequenceRecord);

  return {
    exists: Boolean(sequenceRecord),
    source: "document_category",
    documentType,
    documentCategoryCode: category.code,
    prefix: category.sequence_prefix,
    dateFormat: mappedSequence?.dateFormat ?? fallback.dateFormat,
    separator: mappedSequence?.separator ?? fallback.separator,
    numberLength: category.number_length,
    resetPeriod: category.reset_period,
    currentNumber: mappedSequence?.currentNumber ?? 0,
    lastResetDate: mappedSequence?.lastResetDate ?? null,
    updatedAt: mappedSequence?.updatedAt ?? null,
    updatedBy: mappedSequence?.updatedBy ?? null,
  };
}

async function findDocumentCategory(prisma, { documentType, documentCategoryCode }) {
  const normalizedDocumentType = normalizeDocumentType(documentType);
  const defaultCategoryCode = DOCUMENT_TYPE_CONFIG[normalizedDocumentType].defaultCategoryCode;

  if (documentCategoryCode) {
    const category = await prisma.documentCategory.findUnique({
      where: { code: documentCategoryCode },
      select: {
        code: true,
        entity_type: true,
        sequence_prefix: true,
        number_length: true,
        reset_period: true,
        enabled: true,
        archived_at: true,
      },
    });

    if (!category) {
      throw buildValidationError({ documentCategoryCode: "not_found" }, 409);
    }

    if (category.entity_type !== normalizedDocumentType) {
      throw buildValidationError({ documentCategoryCode: "entity_type_mismatch" }, 409);
    }

    if (!category.enabled || category.archived_at) {
      throw buildValidationError({ documentCategoryCode: "disabled_or_archived" }, 409);
    }

    return category;
  }

  if (defaultCategoryCode) {
    const defaultCategory = await prisma.documentCategory.findUnique({
      where: { code: defaultCategoryCode },
      select: {
        code: true,
        entity_type: true,
        sequence_prefix: true,
        number_length: true,
        reset_period: true,
        enabled: true,
        archived_at: true,
      },
    });

    if (
      defaultCategory &&
      defaultCategory.entity_type === normalizedDocumentType &&
      defaultCategory.enabled &&
      !defaultCategory.archived_at
    ) {
      return defaultCategory;
    }
  }

  return prisma.documentCategory.findFirst({
    where: {
      entity_type: normalizedDocumentType,
      enabled: true,
      archived_at: null,
    },
    orderBy: [{ created_at: "asc" }, { code: "asc" }],
    select: {
      code: true,
      entity_type: true,
      sequence_prefix: true,
      number_length: true,
      reset_period: true,
      enabled: true,
      archived_at: true,
    },
  });
}

async function resolveDocumentSequenceConfig(prisma, { documentType, documentCategoryCode = null } = {}) {
  const normalizedDocumentType = normalizeDocumentType(documentType);
  const documentTypeConfig = DOCUMENT_TYPE_CONFIG[normalizedDocumentType];

  const sequenceRecord = await prisma.documentSequence.findUnique({
    where: { document_type: normalizedDocumentType },
    select: {
      document_type: true,
      prefix: true,
      date_format: true,
      separator: true,
      number_length: true,
      reset_period: true,
      current_number: true,
      last_reset_date: true,
      updated_at: true,
      updated_by: true,
    },
  });

  if (documentTypeConfig.preferLegacySequence && !documentCategoryCode && sequenceRecord) {
    return {
      exists: true,
      source: "document_sequence",
      documentCategoryCode: null,
      ...mapSequenceRecord(sequenceRecord),
    };
  }

  const category = await findDocumentCategory(prisma, {
    documentType: normalizedDocumentType,
    documentCategoryCode,
  });

  if (category) {
    return buildConfigFromCategory(normalizedDocumentType, category, sequenceRecord);
  }

  if (sequenceRecord) {
    return {
      exists: true,
      source: "document_sequence",
      documentCategoryCode: null,
      ...mapSequenceRecord(sequenceRecord),
    };
  }

  return buildConfigFromFallback(normalizedDocumentType);
}

function formatDocumentNumber(sequenceConfig, timeZone) {
  const datePart = compactDateString(timeZone);
  const serial = String(sequenceConfig.current_number).padStart(sequenceConfig.number_length, "0");
  return `${sequenceConfig.prefix}${sequenceConfig.separator}${datePart}${sequenceConfig.separator}${serial}`;
}

async function issueDocumentNumber(
  tx,
  { documentType, documentCategoryCode = null, actorId = null, timeZone = "Asia/Shanghai" } = {},
) {
  const normalizedDocumentType = normalizeDocumentType(documentType);
  const config = await resolveDocumentSequenceConfig(tx, {
    documentType: normalizedDocumentType,
    documentCategoryCode,
  });

  const sequenceRecord = await tx.documentSequence.upsert({
    where: { document_type: normalizedDocumentType },
    update: {
      prefix: config.prefix,
      date_format: config.dateFormat,
      separator: config.separator,
      number_length: config.numberLength,
      reset_period: config.resetPeriod,
      current_number: { increment: 1 },
      updated_by: actorId,
    },
    create: {
      document_type: normalizedDocumentType,
      prefix: config.prefix,
      date_format: config.dateFormat,
      separator: config.separator,
      number_length: config.numberLength,
      reset_period: config.resetPeriod,
      current_number: 1,
      updated_by: actorId,
    },
    select: {
      document_type: true,
      prefix: true,
      date_format: true,
      separator: true,
      number_length: true,
      reset_period: true,
      current_number: true,
      last_reset_date: true,
      updated_at: true,
      updated_by: true,
    },
  });

  const mappedSequence = mapSequenceRecord(sequenceRecord);
  return {
    documentNumber: formatDocumentNumber(
      {
        prefix: mappedSequence.prefix,
        separator: mappedSequence.separator,
        number_length: mappedSequence.numberLength,
        current_number: mappedSequence.currentNumber,
      },
      timeZone,
    ),
    sequence: mappedSequence,
    config: {
      ...config,
      currentNumber: mappedSequence.currentNumber,
      updatedAt: mappedSequence.updatedAt,
      updatedBy: mappedSequence.updatedBy,
    },
  };
}

module.exports = {
  normalizeDocumentType,
  resolveDocumentSequenceConfig,
  issueDocumentNumber,
};