package mail

import (
	"context"
	"encoding/json"
	"errors"

	"github.com/jackc/pgx/v5"

	"github.com/ultisuite/ulti-backend/internal/mail/rules"
)

func (s *Service) SimulateRule(ctx context.Context, externalID string, req *simulateRuleRequest) (rules.SimulationResult, error) {
	conditions, actions, err := s.resolveSimulateRule(ctx, externalID, req)
	if err != nil {
		return rules.SimulationResult{}, err
	}

	msg := &rules.Message{
		ID:             "simulation",
		From:           req.Message.From,
		To:             req.Message.To,
		Subject:        req.Message.Subject,
		BodyText:       req.Message.BodyText,
		HasAttachments: req.Message.HasAttachments,
	}

	engine := rules.NewEngine(s.db)
	return engine.SimulateRule(ctx, conditions, actions, msg), nil
}

func (s *Service) resolveSimulateRule(ctx context.Context, externalID string, req *simulateRuleRequest) ([]rules.Condition, []rules.Action, error) {
	if req.RuleID != "" {
		var condJSON, actJSON []byte
		err := s.db.QueryRow(ctx, `
			SELECT conditions, actions
			FROM mail_rules
			WHERE id = $1 AND user_id = (SELECT id FROM users WHERE external_id = $2)
		`, req.RuleID, externalID).Scan(&condJSON, &actJSON)
		if err != nil {
			if errors.Is(err, pgx.ErrNoRows) {
				return nil, nil, ErrNotFound
			}
			return nil, nil, err
		}
		return unmarshalRuleConditionsActions(condJSON, actJSON)
	}

	condJSON, err := json.Marshal(req.Rule.Conditions)
	if err != nil {
		return nil, nil, err
	}
	actJSON, err := json.Marshal(req.Rule.Actions)
	if err != nil {
		return nil, nil, err
	}
	return unmarshalRuleConditionsActions(condJSON, actJSON)
}

func unmarshalRuleConditionsActions(condJSON, actJSON []byte) ([]rules.Condition, []rules.Action, error) {
	var conditions []rules.Condition
	var actions []rules.Action
	if err := json.Unmarshal(condJSON, &conditions); err != nil {
		return nil, nil, err
	}
	if err := json.Unmarshal(actJSON, &actions); err != nil {
		return nil, nil, err
	}
	return conditions, actions, nil
}