package services

import (
	"crypto/rand"
	"database/sql"
	"encoding/hex"
	"fmt"
	"time"

	"github.com/rede5/gohorsejobs/backend/internal/dto"
	"github.com/rede5/gohorsejobs/backend/internal/models"
)

type JobAlertService struct {
	DB           *sql.DB
	EmailService EmailService
}

func NewJobAlertService(db *sql.DB, emailService EmailService) *JobAlertService {
	return &JobAlertService{DB: db, EmailService: emailService}
}

func generateToken() string {
	bytes := make([]byte, 32)
	rand.Read(bytes)
	return hex.EncodeToString(bytes)
}

func (s *JobAlertService) CreateAlert(req dto.CreateJobAlertRequest, userID *string) (*models.JobAlert, error) {
	frequency := "daily"
	if req.Frequency != nil && *req.Frequency == "weekly" {
		frequency = *req.Frequency
	}

	currency := "BRL"
	if req.Currency != nil {
		currency = *req.Currency
	}

	token := generateToken()
	nextSend := time.Now().Add(24 * time.Hour)
	if frequency == "weekly" {
		nextSend = time.Now().Add(7 * 24 * time.Hour)
	}

	query := `
		INSERT INTO job_alerts (
			user_id, search_query, location, employment_type, work_mode,
			salary_min, salary_max, currency, frequency, is_active,
			confirmation_token, next_send_at, created_at, updated_at
		) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14)
		RETURNING id, created_at, updated_at
	`

	alert := &models.JobAlert{
		UserID:         userID,
		SearchQuery:    req.SearchQuery,
		Location:       req.Location,
		EmploymentType: req.EmploymentType,
		WorkMode:       req.WorkMode,
		SalaryMin:      req.SalaryMin,
		SalaryMax:      req.SalaryMax,
		Currency:       currency,
		Frequency:      frequency,
		IsActive:       false, // Requires email confirmation
		ConfirmationToken: &token,
		NextSendAt:     &nextSend,
		CreatedAt:       time.Now(),
		UpdatedAt:       time.Now(),
	}

	err := s.DB.QueryRow(
		query,
		alert.UserID, alert.SearchQuery, alert.Location, alert.EmploymentType, alert.WorkMode,
		alert.SalaryMin, alert.SalaryMax, alert.Currency, alert.Frequency, alert.IsActive,
		alert.ConfirmationToken, alert.NextSendAt, alert.CreatedAt, alert.UpdatedAt,
	).Scan(&alert.ID, &alert.CreatedAt, &alert.UpdatedAt)

	if err != nil {
		return nil, fmt.Errorf("failed to create alert: %w", err)
	}

	// Send confirmation email
	email := ""
	if userID == nil && req.Email != nil {
		email = *req.Email
	} else if userID != nil {
		// Get user email
		var userEmail string
		err := s.DB.QueryRow("SELECT email FROM users WHERE id = $1", userID).Scan(&userEmail)
		if err == nil {
			email = userEmail
		}
	}

	if email != "" {
		confirmLink := fmt.Sprintf("https://gohorsejobs.com/alerts/confirm?token=%s", token)
		subject := "Confirme seu alerta de vagas no GoHorse Jobs"
		body := fmt.Sprintf(`
			Olá,
			
			Confirme seu alerta de vagas para receber as melhores oportunidades.
			
			Link de confirmação: %s
			
			Se você não criou este alerta, ignore este email.
		`, confirmLink)
		go s.EmailService.SendEmail(email, subject, body)
	}

	return alert, nil
}

func (s *JobAlertService) ConfirmAlert(token string) (*models.JobAlert, error) {
	var alert models.JobAlert
	query := `
		SELECT id, user_id, search_query, location, employment_type, work_mode,
			   salary_min, salary_max, currency, frequency, is_active,
			   confirmation_token, confirmed_at, created_at, updated_at
		FROM job_alerts WHERE confirmation_token = $1
	`

	err := s.DB.QueryRow(query, token).Scan(
		&alert.ID, &alert.UserID, &alert.SearchQuery, &alert.Location, &alert.EmploymentType, &alert.WorkMode,
		&alert.SalaryMin, &alert.SalaryMax, &alert.Currency, &alert.Frequency, &alert.IsActive,
		&alert.ConfirmationToken, &alert.ConfirmedAt, &alert.CreatedAt, &alert.UpdatedAt,
	)

	if err != nil {
		return nil, err
	}

	if alert.ConfirmedAt != nil {
		return &alert, nil // Already confirmed
	}

	now := time.Now()
	nextSend := now.Add(24 * time.Hour)
	if alert.Frequency == "weekly" {
		nextSend = now.Add(7 * 24 * time.Hour)
	}

	_, err = s.DB.Exec(
		"UPDATE job_alerts SET is_active = true, confirmed_at = $1, next_send_at = $2 WHERE id = $3",
		now, nextSend, alert.ID,
	)

	if err != nil {
		return nil, err
	}

	alert.IsActive = true
	alert.ConfirmedAt = &now
	alert.NextSendAt = &nextSend

	return &alert, nil
}

func (s *JobAlertService) GetAlertsByUser(userID string) ([]models.JobAlert, error) {
	query := `
		SELECT id, user_id, search_query, location, employment_type, work_mode,
			   salary_min, salary_max, currency, frequency, is_active,
			   last_sent_at, next_send_at, confirmed_at, created_at, updated_at
		FROM job_alerts WHERE user_id = $1 ORDER BY created_at DESC
	`

	rows, err := s.DB.Query(query, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var alerts []models.JobAlert
	for rows.Next() {
		var alert models.JobAlert
		err := rows.Scan(
			&alert.ID, &alert.UserID, &alert.SearchQuery, &alert.Location, &alert.EmploymentType, &alert.WorkMode,
			&alert.SalaryMin, &alert.SalaryMax, &alert.Currency, &alert.Frequency, &alert.IsActive,
			&alert.LastSentAt, &alert.NextSendAt, &alert.ConfirmedAt, &alert.CreatedAt, &alert.UpdatedAt,
		)
		if err != nil {
			return nil, err
		}
		alerts = append(alerts, alert)
	}

	return alerts, nil
}

func (s *JobAlertService) DeleteAlert(id string, userID string) error {
	result, err := s.DB.Exec("DELETE FROM job_alerts WHERE id = $1 AND user_id = $2", id, userID)
	if err != nil {
		return err
	}

	rowsAffected, _ := result.RowsAffected()
	if rowsAffected == 0 {
		return sql.ErrNoRows
	}

	return nil
}

func (s *JobAlertService) ToggleAlert(id string, userID string, active bool) error {
	_, err := s.DB.Exec("UPDATE job_alerts SET is_active = $1, updated_at = $2 WHERE id = $3 AND user_id = $4",
		active, time.Now(), id, userID)
	return err
}