import { Injectable } from '@nestjs/common';
import { BaseQueryCoreDto } from './dto/base-query-core.dto';
import * as _ from 'lodash';
import { Prisma } from '@prisma/client';

@Injectable()
export class BaseQueryCoreService {
  // Cache for storing relationship metadata to avoid repeated lookups
  private relationshipCache: Map<string, 'one-to-many' | 'one-to-one'> =
    new Map();
  generatePrismaQuery(query: BaseQueryCoreDto = {}) {
    const tempQuery: any = { ...query };
    if (typeof tempQuery?.orderBy === 'string') {
      tempQuery.orderBy = [tempQuery?.orderBy];
    }
    if (typeof tempQuery?.include === 'string') {
      tempQuery.include = [tempQuery?.include];
    }
    if (typeof tempQuery?.search_column === 'string') {
      tempQuery.search_column = [tempQuery?.search_column];
    }
    // Add this: Convert multi_search to array if it's a string
    if (typeof tempQuery?.multi_search === 'string') {
      tempQuery.multi_search = [tempQuery?.multi_search];
    }

    if (tempQuery?.orderBy?.length > 0) {
      const orderBy = {};
      tempQuery.orderBy.forEach((ob) => {
        let sortField = ob.split('|')[0];

        sortField = sortField.split('.');

        if (sortField.length > 1) {
          orderBy[sortField[0]] = this.getOrderByArray(
            sortField,
            ob.split('|')[1],
          );
        } else {
          orderBy[sortField[0]] = ob.split('|')[1];
        }
      });

      tempQuery.orderBy = orderBy;
    }

    if (tempQuery?.include?.length > 0) {
      const formattedQry = this.formatIncludeQueryArray(
        tempQuery.include.sort(),
      );

      const { include } = this.getIncludeArray(formattedQry);

      tempQuery.include = include;
    }

    if (tempQuery?.search_column?.length > 0 && tempQuery?.search?.length > 0) {
      const searchType = tempQuery?.search_type || 'contains';
      const searchCondition = this.createSearchCondition(
        tempQuery.search,
        searchType,
      );

      const formattedSearchQry = this.formatSearchQueryArray(
        tempQuery.search_column.sort(),
        searchCondition,
      );

      tempQuery['where'] = formattedSearchQry;
    }

    // Handle multi-criteria search
    if (tempQuery?.multi_search?.length > 0) {
      const multiSearchConditions = this.formatMultiSearchQueryArray(
        tempQuery.multi_search,
      );
      tempQuery['where'] = { AND: multiSearchConditions };
    }

    delete tempQuery?.search_column;
    delete tempQuery?.search;
    delete tempQuery?.search_type;
    delete tempQuery?.multi_search;

    return tempQuery;
  }

  formatIncludeQueryArray(queryArr: any, baseVal: any = true) {
    let returnObj = {};

    queryArr.map((qry, i) => {
      const rslt = this.formatArray(qry, baseVal);
      if (i > 0) {
        returnObj = _.merge(returnObj, rslt);
      } else {
        returnObj = rslt;
      }
    });

    return returnObj;
  }

  formatSearchQueryArray(queryArr: any, baseVal: any) {
    const searchConditions: any[] = [];

    queryArr.forEach((qry: any) => {
      searchConditions.push(this.formatArray(qry, baseVal));
    });

    return { OR: searchConditions };
  }

  formatMultiSearchQueryArray(multiSearchArr: string[]) {
    // Group conditions by column
    const columnGroups: { [key: string]: any[] } = {};

    multiSearchArr.forEach((searchString: string) => {
      const [searchTerm, column, searchType] = searchString.split('|');

      if (searchTerm && column) {
        const condition = this.createSearchCondition(
          searchTerm.trim(),
          (searchType || 'contains').trim() as 'contains' | 'equals',
        );

        const formattedCondition = this.formatMultiSearchArray(
          column,
          condition,
        );

        // Group by column name
        if (!columnGroups[column]) {
          columnGroups[column] = [];
        }
        columnGroups[column].push(formattedCondition);
      }
    });

    // Convert grouped conditions to final query structure
    const finalConditions: any[] = [];

    Object.keys(columnGroups).forEach((column) => {
      const conditions = columnGroups[column];

      if (conditions.length === 1) {
        // Single condition for this column
        finalConditions.push(conditions[0]);
      } else {
        // Multiple conditions for same column - use OR
        finalConditions.push({ OR: conditions });
      }
    });

    return finalConditions;
  }

  createSearchCondition(
    searchValue: string,
    searchType: 'contains' | 'equals',
  ) {
    const condition: any = {};

    if (searchType === 'contains') {
      condition.contains = searchValue;
      condition.mode = 'insensitive';
    } else if (searchType === 'equals') {
      condition.equals = searchValue;
    }

    return condition;
  }

  formatArray(qry: any, baseVal: any) {
    const returnObj = {};

    const qArr = qry.split('.');

    if (qArr.length > 1) {
      const ky = qArr[0];
      qArr.shift();

      if (typeof returnObj[ky] === 'undefined') {
        returnObj[ky] = this.formatArray(qArr.join('.'), baseVal);
      } else {
        returnObj[ky] = {
          ...returnObj[ky],
          ...this.formatArray(qArr.join('.'), baseVal),
        };
      }
    } else {
      returnObj[qArr[0]] = baseVal;
    }

    return returnObj;
  }

  /**
   * Format array specifically for multi-search functionality
   * This method handles nested relations and applies dynamic relationship detection
   */
  formatMultiSearchArray(qry: any, baseVal: any) {
    const returnObj = {};

    const qArr = qry.split('.');

    if (qArr.length > 1) {
      const ky = qArr[0];
      qArr.shift();

      // Recursively build nested condition
      const nestedCondition = this.formatMultiSearchArray(
        qArr.join('.'),
        baseVal,
      );

      if (typeof returnObj[ky] === 'undefined') {
        // Apply dynamic relation wrapping for where conditions
        returnObj[ky] = this.wrapRelationCondition(ky, nestedCondition);
      } else {
        returnObj[ky] = {
          ...returnObj[ky],
          ...this.wrapRelationCondition(ky, nestedCondition),
        };
      }
    } else {
      returnObj[qArr[0]] = baseVal;
    }

    return returnObj;
  }

  /**
   * Wrap relation conditions with proper Prisma syntax
   * For one-to-many relations, use 'some'
   * For one-to-one relations, use 'is'
   * Dynamically detects relationship type from Prisma DMMF
   */
  private wrapRelationCondition(relationName: string, condition: any) {
    const relationType = this.detectRelationType(relationName);

    if (relationType === 'one-to-many') {
      return { some: condition };
    } else {
      return { is: condition };
    }
  }

  /**
   * Dynamically detect if a relation is one-to-many or one-to-one
   * Uses Prisma's DMMF (Data Model Meta Format) to introspect the schema
   */
  private detectRelationType(
    relationName: string,
  ): 'one-to-many' | 'one-to-one' {
    // Check cache first
    if (this.relationshipCache.has(relationName)) {
      return this.relationshipCache.get(relationName)!;
    }

    try {
      // Access Prisma's DMMF (Data Model Meta Format) for schema introspection
      const dmmf = Prisma.dmmf;

      // Search through all models to find the relation
      for (const model of dmmf.datamodel.models) {
        const field = model.fields.find((f) => f.name === relationName);

        if (field && field.kind === 'object') {
          // Check if it's a list (array) which indicates one-to-many
          const relationType = field.isList ? 'one-to-many' : 'one-to-one';

          // Cache the result
          this.relationshipCache.set(relationName, relationType);

          return relationType;
        }
      }

      // Default to one-to-one if not found (safer default for filtering)
      // This prevents incorrect 'some' usage on non-existent relations
      this.relationshipCache.set(relationName, 'one-to-one');
      return 'one-to-one';
    } catch {
      // Fallback: If DMMF is not accessible, use one-to-one as safe default
      console.warn(
        `Could not detect relation type for "${relationName}". Defaulting to one-to-one.`,
      );
      this.relationshipCache.set(relationName, 'one-to-one');
      return 'one-to-one';
    }
  }

  getOrderByArray(fieldArr: any, sort) {
    fieldArr.shift();

    const incO: any = {};
    incO[fieldArr[0]] =
      fieldArr.length > 1 ? this.getOrderByArray(fieldArr, sort) : sort;

    return incO;
  }

  getIncludeArray(incArr: any) {
    const include = {};

    for (const key in incArr) {
      if (incArr.hasOwnProperty(key)) {
        if (incArr[key] === true) {
          include[key] = true;
        } else {
          include[key] = this.getIncludeArray(incArr[key]);
        }
      }
    }

    return { include };
  }
}