import { DRIZZLE_PROVIDER } from 'src/database/drizzle-provider';
import { Inject, Injectable, HttpException, HttpStatus } from '@nestjs/common';
import { NodePgDatabase } from 'drizzle-orm/node-postgres';
import * as schema from 'src/database/index';
import { trainingSurveys } from 'src/database/index';
import { eq, like, or, and, gte, lte, SQL, sql } from 'drizzle-orm';
import { CreateTrainingDto } from './dto/create-training.dto';
import { UpdateTrainingDto } from './dto/update-training.dto';
import { TrainingStatisticsFilterDto } from './dto/training-statistics-filter.dto';
import { states } from 'src/database/index';
import { PaginationDto } from '../../common/dto/pagination.dto';

@Injectable()
export class TrainingService {
    constructor(
        @Inject(DRIZZLE_PROVIDER) private drizzle: NodePgDatabase<typeof schema>,
    ) { }


    async findAll(paginationDto?: PaginationDto) {
        const { page = 1, limit = 10, search = '', sortBy = 'id', sortOrder = 'asc' } = paginationDto || {};

        const offset = (page - 1) * limit;

        let searchCondition: SQL<unknown> | undefined;
        if (search) {
            searchCondition = or(
                like(trainingSurveys.firstname, `%${search}%`),
                like(trainingSurveys.lastname, `%${search}%`),
                like(trainingSurveys.ospName, `%${search}%`),
                like(trainingSurveys.ospRif, `%${search}%`)
            );
        }

        const orderBy = sortOrder === 'asc'
            ? sql`${trainingSurveys[sortBy as keyof typeof trainingSurveys]} asc`
            : sql`${trainingSurveys[sortBy as keyof typeof trainingSurveys]} desc`;

        const totalCountResult = await this.drizzle
            .select({ count: sql<number>`count(*)` })
            .from(trainingSurveys)
            .where(searchCondition);

        const totalCount = Number(totalCountResult[0].count);
        const totalPages = Math.ceil(totalCount / limit);

        const data = await this.drizzle
            .select()
            .from(trainingSurveys)
            .where(searchCondition)
            .orderBy(orderBy)
            .limit(limit)
            .offset(offset);

        const meta = {
            page,
            limit,
            totalCount,
            totalPages,
            hasNextPage: page < totalPages,
            hasPreviousPage: page > 1,
            nextPage: page < totalPages ? page + 1 : null,
            previousPage: page > 1 ? page - 1 : null,
        };

        return { data, meta };
    }

    async getStatistics(filterDto: TrainingStatisticsFilterDto) {
        const { startDate, endDate, stateId, municipalityId, parishId, ospType } = filterDto;

        const filters: SQL[] = [];

        if (startDate) {
            filters.push(gte(trainingSurveys.visitDate, new Date(startDate)));
        }

        if (endDate) {
            filters.push(lte(trainingSurveys.visitDate, new Date(endDate)));
        }

        if (stateId) {
            filters.push(eq(trainingSurveys.state, stateId));
        }

        if (municipalityId) {
            filters.push(eq(trainingSurveys.municipality, municipalityId));
        }

        if (parishId) {
            filters.push(eq(trainingSurveys.parish, parishId));
        }

        if (ospType) {
            filters.push(eq(trainingSurveys.ospType, ospType));
        }

        const whereCondition = filters.length > 0 ? and(...filters) : undefined;

        const totalOspsResult = await this.drizzle
            .select({ count: sql<number>`count(*)` })
            .from(trainingSurveys)
            .where(whereCondition);
        const totalOsps = Number(totalOspsResult[0].count);

        const totalProducersResult = await this.drizzle
            .select({ sum: sql<number>`sum(${trainingSurveys.producerCount})` })
            .from(trainingSurveys)
            .where(whereCondition);
        const totalProducers = Number(totalProducersResult[0].sum || 0);

        const statusDistribution = await this.drizzle
            .select({
                name: trainingSurveys.currentStatus,
                value: sql<number>`count(*)`
            })
            .from(trainingSurveys)
            .where(whereCondition)
            .groupBy(trainingSurveys.currentStatus);

        const activityDistribution = await this.drizzle
            .select({
                name: trainingSurveys.productiveActivity,
                value: sql<number>`count(*)`
            })
            .from(trainingSurveys)
            .where(whereCondition)
            .groupBy(trainingSurveys.productiveActivity);

        const typeDistribution = await this.drizzle
            .select({
                name: trainingSurveys.ospType,
                value: sql<number>`count(*)`
            })
            .from(trainingSurveys)
            .where(whereCondition)
            .groupBy(trainingSurveys.ospType);

        // New Aggregations
        const stateDistribution = await this.drizzle
            .select({
                name: states.name,
                value: sql<number>`count(${trainingSurveys.id})`
            })
            .from(trainingSurveys)
            .leftJoin(states, eq(trainingSurveys.state, states.id))
            .where(whereCondition)
            .groupBy(states.name);

        const yearDistribution = await this.drizzle
            .select({
                name: sql<string>`cast(${trainingSurveys.companyConstitutionYear} as text)`,
                value: sql<number>`count(*)`
            })
            .from(trainingSurveys)
            .where(whereCondition)
            .groupBy(trainingSurveys.companyConstitutionYear)
            .orderBy(trainingSurveys.companyConstitutionYear);

        return {
            totalOsps,
            totalProducers,
            statusDistribution: statusDistribution.map(item => ({ ...item, value: Number(item.value) })),
            activityDistribution: activityDistribution.map(item => ({ ...item, value: Number(item.value) })),
            typeDistribution: typeDistribution.map(item => ({ ...item, value: Number(item.value) })),
            stateDistribution: stateDistribution.map(item => ({ ...item, value: Number(item.value) })),
            yearDistribution: yearDistribution.map(item => ({ ...item, value: Number(item.value) })),
        };
    }

    async findOne(id: number) {
        const find = await this.drizzle
            .select()
            .from(trainingSurveys)
            .where(eq(trainingSurveys.id, id));

        if (find.length === 0) {
            throw new HttpException('Training record not found', HttpStatus.NOT_FOUND);
        }

        return find[0];
    }

    async create(createTrainingDto: CreateTrainingDto) {
        const [newRecord] = await this.drizzle
            .insert(trainingSurveys)
            .values({
                ...createTrainingDto,
                visitDate: new Date(createTrainingDto.visitDate),
            })
            .returning();

        return newRecord;
    }

    async update(id: number, updateTrainingDto: UpdateTrainingDto) {
        await this.findOne(id);

        const updateData: any = { ...updateTrainingDto };
        if (updateTrainingDto.visitDate) {
            updateData.visitDate = new Date(updateTrainingDto.visitDate);
        }

        const [updatedRecord] = await this.drizzle
            .update(trainingSurveys)
            .set(updateData)
            .where(eq(trainingSurveys.id, id))
            .returning();

        return updatedRecord;
    }

    async remove(id: number) {
        await this.findOne(id);

        const [deletedRecord] = await this.drizzle
            .delete(trainingSurveys)
            .where(eq(trainingSurveys.id, id))
            .returning();

        return { message: 'Training record deleted successfully', data: deletedRecord };
    }
}