package service

import (
	"context"
	"fmt"
	"time"

	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/repository"
)

// WorkingHourService implements business logic for working hours / out-of-office detection.
// Reference: Chatwoot app/models/concerns/out_of_offisable.rb
type WorkingHourService struct {
	whRepo      *repository.WorkingHourRepo
	inboxRepo   *repository.InboxRepo
	accountRepo *repository.AccountRepo
}

func NewWorkingHourService(whRepo *repository.WorkingHourRepo, inboxRepo *repository.InboxRepo, accountRepo *repository.AccountRepo) *WorkingHourService {
	return &WorkingHourService{whRepo: whRepo, inboxRepo: inboxRepo, accountRepo: accountRepo}
}

// IsOutOfOffice checks whether an inbox is currently out of office.
// Reference: Chatwoot out_of_offisable.rb — out_of_office?
//   - Returns true if: working_hours_enabled AND today's working hour says closed_now
func (s *WorkingHourService) IsOutOfOffice(ctx context.Context, inboxID uint) (bool, error) {
	inbox, err := s.inboxRepo.FindByID(ctx, inboxID)
	if err != nil {
		return false, fmt.Errorf("inbox not found: %w", err)
	}

	// Chatwoot: "working_hours_enabled?" must be true to check out-of-office
	if !inbox.WorkingHoursEnabled {
		return false, nil // working hours not enabled → always "in office"
	}

	// Get today's day_of_week in the inbox's timezone
	// Chatwoot: Time.zone.now.in_time_zone(inbox.timezone).to_date.wday
	tz := time.UTC
	if inbox.Timezone != "" {
		loc, err := time.LoadLocation(inbox.Timezone)
		if err == nil {
			tz = loc
		}
	}
	now := time.Now().In(tz)
	dayOfWeek := int(now.Weekday()) // Sunday=0 in Go, matching Chatwoot

	// Find the working hour for today
	wh, err := s.whRepo.FindByInboxAndDay(ctx, inboxID, dayOfWeek)
	if err != nil {
		// No working hour record for this day → assume closed
		return true, nil
	}

	return s.isClosedNow(wh, now, tz), nil
}

// isClosedNow checks whether a specific WorkingHour indicates the inbox is closed right now.
// Reference: Chatwoot working_hour.rb — closed_now?
//   - closed_all_day → always closed
//   - open_all_day → never closed
//   - otherwise: check if current time is outside [open_time, close_time)
func (s *WorkingHourService) isClosedNow(wh *model.WorkingHour, now time.Time, tz *time.Location) bool {
	if wh.ClosedAllDay {
		return true
	}
	if wh.OpenAllDay {
		return false
	}
	if wh.OpenHour == nil || wh.CloseHour == nil {
		return true // missing data → assume closed
	}

	// Chatwoot: open_at?(time) and closed_now? logic
	//   open_time = today at open_hour:open_minutes in inbox timezone
	//   close_time = today at close_hour:close_minutes in inbox timezone
	openMinutes := *wh.OpenHour * 60 + *wh.OpenMinutes
	closeMinutes := *wh.CloseHour * 60 + *wh.CloseMinutes
	currentMinutes := now.Hour() * 60 + now.Minute()

	// closed_now: current time is NOT within open_time..close_time
	// Chatwoot: open_at?(time) → time >= open_time && time < close_time
	return currentMinutes < openMinutes || currentMinutes >= closeMinutes
}

// GetWeeklySchedule returns the 7-day working hours schedule for an inbox.
// Reference: Chatwoot out_of_offisable.rb — weekly_schedule
func (s *WorkingHourService) GetWeeklySchedule(ctx context.Context, inboxID uint) ([]WeeklyScheduleEntry, error) {
	hours, err := s.whRepo.FindByInbox(ctx, inboxID)
	if err != nil {
		return nil, err
	}

	entries := make([]WeeklyScheduleEntry, 0, len(hours))
	for _, wh := range hours {
		entry := WeeklyScheduleEntry{
			DayOfWeek:    wh.DayOfWeek,
			ClosedAllDay: wh.ClosedAllDay,
			OpenAllDay:   wh.OpenAllDay,
			OpenHour:     wh.OpenHour,
			OpenMinutes:  wh.OpenMinutes,
			CloseHour:    wh.CloseHour,
			CloseMinutes: wh.CloseMinutes,
		}
		entries = append(entries, entry)
	}
	return entries, nil
}

// UpdateWeeklySchedule bulk-updates the working hours schedule.
// Reference: Chatwoot out_of_offisable.rb — update_working_hours(params)
//   - Validates each entry before saving
//   - Runs updates in a transaction
func (s *WorkingHourService) UpdateWeeklySchedule(ctx context.Context, inboxID uint, params []repository.WorkingHourUpdateParam) ([]WeeklyScheduleEntry, error) {
	// Validate each entry first
	for i, p := range params {
		temp := &model.WorkingHour{
			DayOfWeek:    p.DayOfWeek,
			ClosedAllDay: p.ClosedAllDay,
			OpenAllDay:   p.OpenAllDay,
			OpenHour:     p.OpenHour,
			OpenMinutes:  p.OpenMinutes,
			CloseHour:    p.CloseHour,
			CloseMinutes: p.CloseMinutes,
		}
		temp.EnsureOpenAllDayHours()
		if errs := temp.Validate(); len(errs) > 0 {
			return nil, fmt.Errorf("validation error for day %d (entry %d): %v", p.DayOfWeek, i, errs)
		}
	}

	if err := s.whRepo.UpdateWorkingHours(ctx, inboxID, params); err != nil {
		return nil, fmt.Errorf("update working hours: %w", err)
	}

	return s.GetWeeklySchedule(ctx, inboxID)
}

// InitDefaultWorkingHours creates the 7 default working hours when an inbox is created.
// Reference: Chatwoot out_of_offisable.rb — after_create :create_default_working_hours
func (s *WorkingHourService) InitDefaultWorkingHours(ctx context.Context, inboxID, accountID uint) error {
	return s.whRepo.CreateDefaultWorkingHours(ctx, inboxID, accountID)
}

// WeeklyScheduleEntry is the JSON response format for working hours.
// Reference: Chatwoot out_of_offisable.rb — weekly_schedule
type WeeklyScheduleEntry struct {
	DayOfWeek    int  `json:"day_of_week"`
	ClosedAllDay bool `json:"closed_all_day"`
	OpenAllDay   bool `json:"open_all_day"`
	OpenHour     *int `json:"open_hour"`
	OpenMinutes  *int `json:"open_minutes"`
	CloseHour    *int `json:"close_hour"`
	CloseMinutes *int `json:"close_minutes"`
}