package repository

import (
	"context"
	"errors"

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

	"financeiro-carvalho/internal/model"
)

type ManualTransactionRepository interface {
	List(ctx context.Context, month string) ([]model.Transaction, error)
	GetByID(ctx context.Context, id int) (*model.Transaction, error)
	Create(ctx context.Context, t model.Transaction) (*model.Transaction, error)
	Update(ctx context.Context, t model.Transaction) (*model.Transaction, error)
	Delete(ctx context.Context, id int) error
	// HasMatchingTransaction checks if a category has an expense in the given month.
	HasMatchingTransaction(ctx context.Context, categoryID *int, month string, amount float64) (bool, error)
}

type manualTxRepo struct{ db *pgxpool.Pool }

func NewManualTransactionRepository(db *pgxpool.Pool) ManualTransactionRepository {
	return &manualTxRepo{db: db}
}

func (r *manualTxRepo) List(ctx context.Context, month string) ([]model.Transaction, error) {
	query := `
		SELECT id, date::text, amount, description, type, source, category_id, account_id, created_at, updated_at
		FROM transactions`
	args := []any{}
	if month != "" {
		query += ` WHERE TO_CHAR(date, 'YYYY-MM') = $1`
		args = append(args, month)
	}
	query += ` ORDER BY date DESC, id DESC`

	rows, err := r.db.Query(ctx, query, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []model.Transaction
	for rows.Next() {
		var t model.Transaction
		if err := rows.Scan(&t.ID, &t.Date, &t.Amount, &t.Description, &t.Type, &t.Source, &t.CategoryID, &t.AccountID, &t.CreatedAt, &t.UpdatedAt); err != nil {
			return nil, err
		}
		out = append(out, t)
	}
	return out, rows.Err()
}

func (r *manualTxRepo) GetByID(ctx context.Context, id int) (*model.Transaction, error) {
	var t model.Transaction
	err := r.db.QueryRow(ctx, `
		SELECT id, date::text, amount, description, type, source, category_id, account_id, created_at, updated_at
		FROM transactions WHERE id = $1`, id).
		Scan(&t.ID, &t.Date, &t.Amount, &t.Description, &t.Type, &t.Source, &t.CategoryID, &t.AccountID, &t.CreatedAt, &t.UpdatedAt)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, ErrNotFound
	}
	return &t, err
}

func (r *manualTxRepo) Create(ctx context.Context, t model.Transaction) (*model.Transaction, error) {
	var out model.Transaction
	err := r.db.QueryRow(ctx, `
		INSERT INTO transactions (date, amount, description, type, source, category_id, account_id)
		VALUES ($1, $2, $3, $4, 'manual', $5, $6)
		RETURNING id, date::text, amount, description, type, source, category_id, account_id, created_at, updated_at`,
		t.Date, t.Amount, t.Description, t.Type, t.CategoryID, t.AccountID).
		Scan(&out.ID, &out.Date, &out.Amount, &out.Description, &out.Type, &out.Source, &out.CategoryID, &out.AccountID, &out.CreatedAt, &out.UpdatedAt)
	return &out, err
}

func (r *manualTxRepo) Update(ctx context.Context, t model.Transaction) (*model.Transaction, error) {
	var out model.Transaction
	err := r.db.QueryRow(ctx, `
		UPDATE transactions
		SET date=$1, amount=$2, description=$3, type=$4, category_id=$5, account_id=$6, updated_at=NOW()
		WHERE id=$7 AND source='manual'
		RETURNING id, date::text, amount, description, type, source, category_id, account_id, created_at, updated_at`,
		t.Date, t.Amount, t.Description, t.Type, t.CategoryID, t.AccountID, t.ID).
		Scan(&out.ID, &out.Date, &out.Amount, &out.Description, &out.Type, &out.Source, &out.CategoryID, &out.AccountID, &out.CreatedAt, &out.UpdatedAt)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, ErrNotFound
	}
	return &out, err
}

func (r *manualTxRepo) Delete(ctx context.Context, id int) error {
	tag, err := r.db.Exec(ctx, `DELETE FROM transactions WHERE id = $1 AND source = 'manual'`, id)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return ErrNotFound
	}
	return nil
}

func (r *manualTxRepo) HasMatchingTransaction(ctx context.Context, categoryID *int, month string, amount float64) (bool, error) {
	var count int
	var err error
	if categoryID != nil {
		err = r.db.QueryRow(ctx, `
			SELECT COUNT(*) FROM transactions
			WHERE category_id = $1
			  AND TO_CHAR(date, 'YYYY-MM') = $2
			  AND type = 'expense'
			  AND amount BETWEEN $3 * 0.9 AND $3 * 1.1`,
			*categoryID, month, amount).Scan(&count)
	} else {
		// No category set — cannot auto-match, always report as uncovered
		return false, nil
	}
	return count > 0, err
}