package cli

import (
	"errors"
	"fmt"
	"time"

	"gitea.maximumdirect.net/eric/weatherreporter/internal/app"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/timeutil"
)

var (
	errReportDateRequired    = errors.New("report date is required")
	errReportDateNotAccepted = errors.New("report does not accept a date")
)

type reportDatePolicy struct {
	acceptsDate         bool
	requiresDate        bool
	defaultsToLocalDate bool
}

func reportDatePolicyFor(report app.ReportKind) reportDatePolicy {
	switch report {
	case app.ReportDaily:
		return reportDatePolicy{acceptsDate: true, requiresDate: true}
	case app.ReportToday:
		return reportDatePolicy{acceptsDate: true, defaultsToLocalDate: true}
	default:
		return reportDatePolicy{}
	}
}

func addReportDateFlag(fs interface {
	StringVar(*string, string, string, string)
}, report app.ReportKind, value *string) {
	if reportDatePolicyFor(report).acceptsDate {
		fs.StringVar(value, "date", "", "report date in YYYY-MM-DD")
	}
}

func reportDateRequiredError(action string, report app.ReportKind, value string) error {
	if reportDatePolicyFor(report).requiresDate && value == "" {
		return fmt.Errorf("%s %s requires --date YYYY-MM-DD", action, report)
	}
	return nil
}

func resolveActionReportDate(action string, report app.ReportKind, value string, location *time.Location, now time.Time) (time.Time, error) {
	date, err := resolveReportDate(report, value, location, now)
	if errors.Is(err, errReportDateRequired) {
		return time.Time{}, fmt.Errorf("%s %s requires --date YYYY-MM-DD", action, report)
	}
	return date, err
}

func resolveReportDate(report app.ReportKind, value string, location *time.Location, now time.Time) (time.Time, error) {
	policy := reportDatePolicyFor(report)
	if !policy.acceptsDate {
		if value != "" {
			return time.Time{}, errReportDateNotAccepted
		}
		return time.Time{}, nil
	}
	if value == "" {
		if policy.requiresDate {
			return time.Time{}, errReportDateRequired
		}
		if policy.defaultsToLocalDate {
			return timeutil.LocalDate(now, location), nil
		}
		return time.Time{}, nil
	}
	return timeutil.ParseLocalDate(value, location)
}