package server

import (
	"errors"
	"fmt"
	"path"
	"text/template"
	"time"

	"git.ctrlz.es/mgdelacroix/birthdaybot/model"
	"git.ctrlz.es/mgdelacroix/birthdaybot/notification"
	"git.ctrlz.es/mgdelacroix/birthdaybot/parser"
	"github.com/charmbracelet/log"
)

var (
	ErrNoNotificationServices = errors.New("there are no notification services configured")
	ErrNoLogger               = errors.New("there is no logger configured")
	ErrNoConfig               = errors.New("configuration is required to create a server")
)

type Server struct {
	Logger               *log.Logger
	Config               *model.Config
	WebServer            *WebServer
	workers              []Worker
	birthdays            []*model.Birthday
	notificationServices []notification.NotificationService
	tmpl                 *template.Template
}

func (s *Server) createNotificationServices() ([]notification.NotificationService, error) {
	notificationServices := []notification.NotificationService{}

	if s.Config.TelegramNotifications != nil {
		telegramNotificationService, err := notification.NewTelegramNotificationService(s.Logger, s.Config)
		if err != nil {
			return nil, fmt.Errorf("cannot create telegram notification service: %w", err)
		}
		notificationServices = append(notificationServices, telegramNotificationService)
	}

	if len(notificationServices) == 0 {
		return nil, ErrNoNotificationServices
	}

	return notificationServices, nil
}

func New(options ...Option) (*Server, error) {
	srv := &Server{}
	for _, option := range options {
		srv = option(srv)
	}

	if srv.Logger == nil {
		return nil, ErrNoLogger
	}

	if srv.Config == nil {
		return nil, ErrNoConfig
	}

	if len(srv.birthdays) == 0 {
		srv.Logger.Debug("parsing CSV file", "birthdayFile", srv.Config.Birthdays.File)

		var err error
		srv.birthdays, err = parser.ParseCSV(srv.Config.Birthdays.File)
		if err != nil {
			srv.Logger.Error("cannot parse CSV file", "birthdayFile", srv.Config.Birthdays.File, "error", err)
			return nil, fmt.Errorf("cannot parse CSV file %s: %w", srv.Config.Birthdays.File, err)
		}
	}

	if len(srv.notificationServices) == 0 {
		srv.Logger.Debug("creating notification services from config")

		var err error
		srv.notificationServices, err = srv.createNotificationServices()
		if err != nil {
			srv.Logger.Error("error creating notification services", "error", err)
			return nil, err
		}
	}

	if len(srv.workers) == 0 {
		srv.Logger.Debug("creating server workers")

		srv.workers = []Worker{NewSimpleWorker(srv)}
	}

	if srv.Config.Birthdays.Template != "" {
		srv.Logger.Debug("parsing birthday template", "file", srv.Config.Birthdays.Template)

		funcs := template.FuncMap{
			"getYearsOld": func(yearOfBirth int) int {
				return time.Now().Year() - yearOfBirth
			},
		}

		var err error
		srv.tmpl, err = template.
			New(path.Base(srv.Config.Birthdays.Template)).
			Funcs(funcs).
			ParseFiles(srv.Config.Birthdays.Template)
		if err != nil {
			return nil, fmt.Errorf("cannot parse template file %q: %w", srv.Config.Birthdays.Template, err)
		}
	}

	if srv.WebServer == nil {
		srv.Logger.Debug("creating web server")

		srv.WebServer = NewWebServer(srv)
	}

	return srv, nil
}

func (s *Server) Start() error {
	s.Logger.Info("starting server")

	if err := s.WebServer.Start(); err != nil {
		return fmt.Errorf("cannot start web server: %w", err)
	}

	for _, worker := range s.workers {
		worker.Start()
	}

	s.Logger.Debug("server started", "workers", len(s.workers))

	return nil
}

func (s *Server) Stop() error {
	s.Logger.Info("stopping server")

	if err := s.WebServer.Stop(); err != nil {
		return fmt.Errorf("cannot stop web server: %w", err)
	}

	for _, worker := range s.workers {
		worker.Stop()
	}

	s.Logger.Debug("server stopped", "workers", len(s.workers))

	return nil
}

func (s *Server) Notify(birthday *model.Birthday) error {
	errs := []error{}
	for _, service := range s.notificationServices {
		err := service.Notify(birthday, s.tmpl)
		if err != nil {
			errs = append(errs, err)
		}
	}

	if len(errs) == 0 {
		return nil
	}
	return errors.Join(errs...)
}

func (s *Server) Birthdays() []*model.Birthday {
	return s.birthdays
}

func (s *Server) NextBirthdays() []*model.Birthday {
	return model.NextBirthdays(s.birthdays, time.Now())
}