package packageduration

import (
	"sort"
	"strconv"

	"git.5iot.com/iotlcm-public/iotlcm-admin-svr/internal/consts"
	"git.5iot.com/iotlcm-public/iotlcm-admin-svr/internal/model/entity"

	"github.com/gogf/gf/v2/encoding/gjson"
	"github.com/gogf/gf/v2/errors/gerror"
	"github.com/gogf/gf/v2/util/gconv"
)

const (
	FlowCycleUnitMonth = "month"
	RenewUnitYear      = "year"
)

// Policy is the normalized duration contract used by package-related business.
// The database keeps the existing fields; this type separates their meanings.
type Policy struct {
	FlowCycleUnit  string
	RenewUnit      string
	RenewableYears []int
	ChangeMonths   []int
}

func FromPackage(pkg *entity.TSimFlowPackageInfo) (*Policy, error) {
	if pkg == nil {
		return nil, gerror.New("package information is empty")
	}
	years, err := RenewableYears(pkg)
	if err != nil {
		return nil, err
	}
	months, err := ChangeMonths(pkg)
	if err != nil {
		return nil, err
	}
	return &Policy{
		FlowCycleUnit:  FlowCycleUnitMonth,
		RenewUnit:      RenewUnitYear,
		RenewableYears: years,
		ChangeMonths:   months,
	}, nil
}

func MonthBillingMethodValue() string {
	return strconv.Itoa(consts.BillingMethodMonth)
}

func RenewableYears(pkg *entity.TSimFlowPackageInfo) ([]int, error) {
	if pkg == nil {
		return nil, gerror.New("package information is empty")
	}
	return renewableYearsFromConfig(pkg.RenewableDurationConfig)
}

func ChangeMonths(pkg *entity.TSimFlowPackageInfo) ([]int, error) {
	if pkg == nil {
		return nil, gerror.New("package information is empty")
	}
	values, legacyMonthConfig, err := rawDurationValues(pkg.RenewableDurationConfig)
	if err != nil {
		return nil, err
	}
	if legacyMonthConfig {
		return uniqueSorted(values), nil
	}

	months := make([]int, 0, len(values))
	for _, year := range values {
		if year <= 0 {
			continue
		}
		months = append(months, year*12)
	}
	months = uniqueSorted(months)
	if len(months) == 0 {
		return nil, gerror.New("package has no valid change duration options")
	}
	return months, nil
}

// NormalizeRenewableDurationConfig converts legacy month values such as
// [12,24,36] into the new year values [1,2,3] before saving a package.
func NormalizeRenewableDurationConfig(config *gjson.Json) (*gjson.Json, error) {
	values, legacyMonthConfig, err := rawDurationValues(config)
	if err != nil {
		return nil, err
	}
	if legacyMonthConfig {
		years := make([]int, 0, len(values))
		for _, month := range values {
			if month > 0 && month%12 == 0 {
				years = append(years, month/12)
			}
		}
		years = uniqueSorted(years)
		if len(years) == 0 {
			return nil, gerror.New("package has no valid renewable duration options")
		}
		return gjson.New(years), nil
	}
	return gjson.New(uniqueSorted(values)), nil
}

func NormalizeRenewableYears(values []int) []int {
	values = uniqueSorted(values)
	if len(values) == 0 {
		return nil
	}
	legacyMonthConfig := true
	for _, value := range values {
		if value < 12 || value%12 != 0 {
			legacyMonthConfig = false
			break
		}
	}
	if !legacyMonthConfig {
		return values
	}
	years := make([]int, 0, len(values))
	for _, month := range values {
		if month > 0 && month%12 == 0 {
			years = append(years, month/12)
		}
	}
	return uniqueSorted(years)
}

func RenewMonths(years int) int {
	if years <= 0 {
		return 0
	}
	return years * 12
}

func renewableYearsFromConfig(config *gjson.Json) ([]int, error) {
	values, legacyMonthConfig, err := rawDurationValues(config)
	if err != nil {
		return nil, err
	}
	years := make([]int, 0, len(values))
	for _, value := range values {
		if value <= 0 {
			continue
		}
		if legacyMonthConfig {
			if value%12 != 0 {
				continue
			}
			value /= 12
		}
		years = append(years, value)
	}
	years = uniqueSorted(years)
	if len(years) == 0 {
		return nil, gerror.New("package has no valid renewable duration options")
	}
	return years, nil
}

func rawDurationValues(config *gjson.Json) ([]int, bool, error) {
	if config == nil || config.IsNil() {
		return nil, false, gerror.New("package has no renewable duration config")
	}
	values := config.Interfaces()
	if len(values) == 0 {
		return nil, false, gerror.New("package has no renewable duration config")
	}

	result := make([]int, 0, len(values))
	for _, value := range values {
		parsed := gconv.Int(value)
		if parsed > 0 {
			result = append(result, parsed)
		}
	}
	result = uniqueSorted(result)
	if len(result) == 0 {
		return nil, false, gerror.New("package has no valid renewable duration options")
	}

	legacyMonthConfig := true
	for _, value := range result {
		if value < 12 || value%12 != 0 {
			legacyMonthConfig = false
			break
		}
	}
	return result, legacyMonthConfig, nil
}

func uniqueSorted(values []int) []int {
	if len(values) == 0 {
		return nil
	}
	seen := make(map[int]struct{}, len(values))
	result := make([]int, 0, len(values))
	for _, value := range values {
		if value <= 0 {
			continue
		}
		if _, exists := seen[value]; exists {
			continue
		}
		seen[value] = struct{}{}
		result = append(result, value)
	}
	sort.Ints(result)
	return result
}