package service

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"time"

	"gorm.io/gorm"

	smokemodel "wx_service/internal/smoke/model"
)

var (
	ErrSmokeProfileInvalidTime = errors.New("invalid time format, expected HH:MM")
)

type SmokeProfileService struct {
	db *gorm.DB
}

func NewSmokeProfileService(db *gorm.DB) *SmokeProfileService {
	return &SmokeProfileService{db: db}
}

type SmokeProfileView struct {
	Exists  bool                         `json:"exists"`
	Profile *smokemodel.SmokeUserProfile `json:"profile,omitempty"`

	IsCompleted            bool `json:"is_completed"`
	AwakeMinutes           int  `json:"awake_minutes"`
	BaselineIntervalMinute int  `json:"baseline_interval_minutes"`
}

func (s *SmokeProfileService) GetView(ctx context.Context, uid int) (SmokeProfileView, error) {
	profile, err := s.Get(ctx, uid)
	if err != nil {
		return SmokeProfileView{}, err
	}
	if profile == nil {
		return SmokeProfileView{
			Exists:                 false,
			Profile:                nil,
			IsCompleted:            false,
			AwakeMinutes:           defaultAwakeMinutes,
			BaselineIntervalMinute: 0,
		}, nil
	}

	awakeMinutes, err := awakeMinutesWithFallback(profile.WakeUpTime, profile.SleepTime)
	if err != nil {
		return SmokeProfileView{}, err
	}

	isCompleted := isSmokeProfileCompleted(*profile)
	interval := baselineIntervalMinutes(awakeMinutes, profile.BaselineCigsPerDay)

	return SmokeProfileView{
		Exists:                 true,
		Profile:                profile,
		IsCompleted:            isCompleted,
		AwakeMinutes:           awakeMinutes,
		BaselineIntervalMinute: interval,
	}, nil
}

func (s *SmokeProfileService) Get(ctx context.Context, uid int) (*smokemodel.SmokeUserProfile, error) {
	var profile smokemodel.SmokeUserProfile
	err := s.db.WithContext(ctx).
		Where("uid = ? AND deleted_at IS NULL", uid).
		First(&profile).Error
	if err == nil {
		return &profile, nil
	}
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, nil
	}
	return nil, fmt.Errorf("load smoke profile: %w", err)
}

type UpsertSmokeProfileRequest struct {
	BaselineCigsPerDay *int
	SmokingYears       *float64
	PackPriceCent      *int

	SmokeMotivations *[]string
	QuitMotivations  *[]string

	WakeUpTime *string
	SleepTime  *string

	QuitDateProvided bool
	QuitDate         *time.Time
}

func (s *SmokeProfileService) Upsert(ctx context.Context, uid int, req UpsertSmokeProfileRequest) (SmokeProfileView, error) {
	var profile smokemodel.SmokeUserProfile
	tx := s.db.WithContext(ctx)
	err := tx.Where("uid = ? AND deleted_at IS NULL", uid).First(&profile).Error
	if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
		return SmokeProfileView{}, fmt.Errorf("load smoke profile: %w", err)
	}
	isNew := errors.Is(err, gorm.ErrRecordNotFound)
	if isNew {
		profile = smokemodel.SmokeUserProfile{UID: uid}
	}

	applyInt := func(dst *int, v *int) {
		if v != nil {
			*dst = *v
		}
	}
	applyFloat := func(dst *float64, v *float64) {
		if v != nil {
			*dst = *v
		}
	}
	applyTimeStr := func(dst *string, v *string) error {
		if v == nil {
			return nil
		}
		value := strings.TrimSpace(*v)
		if value == "" {
			*dst = ""
			return nil
		}
		if _, err := parseHHMMToMinutes(value); err != nil {
			return ErrSmokeProfileInvalidTime
		}
		*dst = value
		return nil
	}

	applyInt(&profile.BaselineCigsPerDay, req.BaselineCigsPerDay)
	applyFloat(&profile.SmokingYears, req.SmokingYears)
	applyInt(&profile.PackPriceCent, req.PackPriceCent)

	if req.SmokeMotivations != nil {
		profile.SmokeMotivations = smokemodel.StringSlice(*req.SmokeMotivations)
	}
	if req.QuitMotivations != nil {
		profile.QuitMotivations = smokemodel.StringSlice(*req.QuitMotivations)
	}

	if err := applyTimeStr(&profile.WakeUpTime, req.WakeUpTime); err != nil {
		return SmokeProfileView{}, err
	}
	if err := applyTimeStr(&profile.SleepTime, req.SleepTime); err != nil {
		return SmokeProfileView{}, err
	}
	if req.QuitDateProvided {
		profile.QuitDate = req.QuitDate
	}

	now := time.Now()
	if profile.OnboardingCompletedAt == nil && isSmokeProfileCompleted(profile) {
		profile.OnboardingCompletedAt = &now
	}

	if isNew {
		if err := tx.Create(&profile).Error; err != nil {
			return SmokeProfileView{}, fmt.Errorf("create smoke profile: %w", err)
		}
	} else {
		if err := tx.Save(&profile).Error; err != nil {
			return SmokeProfileView{}, fmt.Errorf("save smoke profile: %w", err)
		}
	}

	return s.GetView(ctx, uid)
}

func isSmokeProfileCompleted(p smokemodel.SmokeUserProfile) bool {
	return p.BaselineCigsPerDay > 0 &&
		p.PackPriceCent > 0 &&
		len(p.QuitMotivations) > 0 &&
		strings.TrimSpace(p.WakeUpTime) != "" &&
		strings.TrimSpace(p.SleepTime) != ""
}

const defaultAwakeMinutes = 16 * 60

func awakeMinutesWithFallback(wakeUp, sleep string) (int, error) {
	wakeUp = strings.TrimSpace(wakeUp)
	sleep = strings.TrimSpace(sleep)
	if wakeUp == "" || sleep == "" {
		return defaultAwakeMinutes, nil
	}
	wakeMin, err := parseHHMMToMinutes(wakeUp)
	if err != nil {
		return 0, ErrSmokeProfileInvalidTime
	}
	sleepMin, err := parseHHMMToMinutes(sleep)
	if err != nil {
		return 0, ErrSmokeProfileInvalidTime
	}
	if sleepMin == wakeMin {
		return 24 * 60, nil
	}
	if sleepMin > wakeMin {
		return sleepMin - wakeMin, nil
	}
	return (24*60 - wakeMin) + sleepMin, nil
}

func baselineIntervalMinutes(awakeMinutes int, baselineCigsPerDay int) int {
	if awakeMinutes <= 0 || baselineCigsPerDay <= 0 {
		return 0
	}
	interval := awakeMinutes / baselineCigsPerDay
	if interval <= 0 {
		return 1
	}
	return interval
}

func parseHHMMToMinutes(s string) (int, error) {
	s = strings.TrimSpace(s)
	if len(s) != 5 || s[2] != ':' {
		return 0, ErrSmokeProfileInvalidTime
	}
	h1, h2 := s[0], s[1]
	m1, m2 := s[3], s[4]
	if h1 < '0' || h1 > '9' || h2 < '0' || h2 > '9' || m1 < '0' || m1 > '9' || m2 < '0' || m2 > '9' {
		return 0, ErrSmokeProfileInvalidTime
	}
	hour := int(h1-'0')*10 + int(h2-'0')
	min := int(m1-'0')*10 + int(m2-'0')
	if hour < 0 || hour > 23 || min < 0 || min > 59 {
		return 0, ErrSmokeProfileInvalidTime
	}
	return hour*60 + min, nil
}