package repository

import (
	"context"

	"github.com/jackc/pgx/v5/pgxpool"

	"financeiro-carvalho/internal/model"
)

type DashboardRepository struct {
	pool *pgxpool.Pool
}

func NewDashboardRepository(pool *pgxpool.Pool) *DashboardRepository {
	return &DashboardRepository{pool: pool}
}

func (r *DashboardRepository) MonthlySummary(ctx context.Context, month string) (income, expenses float64, err error) {
	row := r.pool.QueryRow(ctx, `
		SELECT
			COALESCE(SUM(CASE WHEN type = 'income'  THEN amount ELSE 0 END), 0),
			COALESCE(SUM(CASE WHEN type = 'expense' THEN amount ELSE 0 END), 0)
		FROM transactions
		WHERE to_char(date, 'YYYY-MM') = $1
	`, month)
	err = row.Scan(&income, &expenses)
	return
}

func (r *DashboardRepository) ByCategory(ctx context.Context, month string) ([]model.CategoryTotal, error) {
	rows, err := r.pool.Query(ctx, `
		SELECT
			t.category_id,
			COALESCE(c.name,  'Sem categoria') AS category_name,
			COALESCE(c.color, '#6B7280')       AS color,
			SUM(t.amount)                      AS total
		FROM transactions t
		LEFT JOIN categories c ON c.id = t.category_id
		WHERE to_char(t.date, 'YYYY-MM') = $1
		  AND t.type = 'expense'
		GROUP BY t.category_id, c.name, c.color
		ORDER BY total DESC
	`, month)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []model.CategoryTotal
	for rows.Next() {
		var ct model.CategoryTotal
		if err := rows.Scan(&ct.CategoryID, &ct.CategoryName, &ct.Color, &ct.Total); err != nil {
			return nil, err
		}
		out = append(out, ct)
	}
	return out, rows.Err()
}

func (r *DashboardRepository) MonthlyEvolution(ctx context.Context, month string) ([]model.MonthEvolution, error) {
	rows, err := r.pool.Query(ctx, `
		SELECT
			to_char(m.ms, 'YYYY-MM')                                                  AS month,
			COALESCE(SUM(CASE WHEN t.type = 'income'  THEN t.amount ELSE 0 END), 0)  AS income,
			COALESCE(SUM(CASE WHEN t.type = 'expense' THEN t.amount ELSE 0 END), 0)  AS expenses
		FROM generate_series(
			date_trunc('month', ($1 || '-01')::date) - INTERVAL '5 months',
			date_trunc('month', ($1 || '-01')::date),
			'1 month'::interval
		) AS m(ms)
		LEFT JOIN transactions t ON date_trunc('month', t.date) = m.ms
		GROUP BY m.ms
		ORDER BY m.ms
	`, month)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []model.MonthEvolution
	for rows.Next() {
		var me model.MonthEvolution
		if err := rows.Scan(&me.Month, &me.Income, &me.Expenses); err != nil {
			return nil, err
		}
		me.Saved = me.Income - me.Expenses
		out = append(out, me)
	}
	return out, rows.Err()
}

func (r *DashboardRepository) RecentTransactions(ctx context.Context, month string) ([]model.RecentTransaction, error) {
	rows, err := r.pool.Query(ctx, `
		SELECT
			t.id,
			t.date::text,
			t.description,
			COALESCE(c.name, 'Sem categoria') AS category_name,
			t.amount,
			t.type
		FROM transactions t
		LEFT JOIN categories c ON c.id = t.category_id
		WHERE to_char(t.date, 'YYYY-MM') = $1
		ORDER BY t.date DESC, t.id DESC
		LIMIT 10
	`, month)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []model.RecentTransaction
	for rows.Next() {
		var rt model.RecentTransaction
		if err := rows.Scan(&rt.ID, &rt.Date, &rt.Description, &rt.CategoryName, &rt.Amount, &rt.Type); err != nil {
			return nil, err
		}
		out = append(out, rt)
	}
	return out, rows.Err()
}