package svg
import (
"errors"
"fmt"
"html"
"math"
"strings"
"time"
"b612.me/astro/internal/svgasset"
"b612.me/astro/moon"
)
const (
localPlanetOccultationSVGDefaultWidth = 1040
localPlanetOccultationSVGDefaultHeight = 760
localPlanetOccultationSVGMinimumWidth = 760
localPlanetOccultationSVGMinimumHeight = 600
localPlanetOccultationSVGDefaultStep = 2 * time.Minute
)
// ErrInvalidLocalPlanetOccultationSVGOptions 表示本地行星图表选项无效。
// ErrInvalidLocalPlanetOccultationSVGOptions reports invalid local planetary chart options.
var ErrInvalidLocalPlanetOccultationSVGOptions = errors.New("invalid local planetary occultation SVG options")
// ErrInvalidLocalPlanetOccultationInfo 表示固定地点行星事件数据格式错误。
// ErrInvalidLocalPlanetOccultationInfo reports malformed fixed-site planetary event data.
var ErrInvalidLocalPlanetOccultationInfo = errors.New("invalid local planetary occultation info")
// LocalPlanetOccultationSVGOptions 控制固定地点月球与行星盘面图。
// LocalPlanetOccultationSVGOptions controls a fixed-site Moon-planet disk chart.
type LocalPlanetOccultationSVGOptions struct {
// Width 和 Height 是 SVG 画布尺寸；非正值使用默认值。
// Width and Height are SVG canvas dimensions. Values <= 0 use defaults.
Width int
Height int
// Step 是月心行星轨迹请求采样步长；零值使用两分钟，负值无效，正值小于一秒时提升到一秒。长事件可能增大实际步长，以保持基础轨迹在有界采样预算内。
// Step is the requested Moon-centered planetary-track sampling step. Zero uses two minutes; negative values are invalid. Positive values below one second are raised to one second, and long events may use a larger effective step to keep the base track within its bounded sample budget.
Step time.Duration
// 空文本字段使用本地化的自动标签。
// Empty text fields use localized automatic labels.
Title string
SummaryText string
GreatestText string
OverviewTitle string
PhasePanelsTitle string
ContactsTitle string
DirectionText string
FooterNote string
// Language 为 "en" 时使用英文，其他值使用中文。
// Language uses English for "en" and Chinese for every other value.
Language string
// Location 控制显示的事件时刻；nil 使用 UTC+8。
// Location controls displayed event times. Nil uses UTC+8.
Location *time.Location
}
type localPlanetOccultationEventFrame struct {
label string
name string
time time.Time
hidden bool
frame moon.PlanetOccultationDiagramFrame
}
// FindLocalPlanetOccultationSVGs 搜索固定观测地点，并渲染请求时间窗口内的每次有限盘面行星月掩。空切片表示没有本地事件。
// FindLocalPlanetOccultationSVGs searches one fixed observing site and renders every finite-disk planetary occultation in the requested time window. An empty slice means no local event.
func FindLocalPlanetOccultationSVGs(
start, end time.Time,
planet moon.OccultationPlanet,
longitude, latitude, height float64,
searchOptions moon.OccultationSearchOptions,
options LocalPlanetOccultationSVGOptions,
) ([]string, error) {
if err := validateLocalPlanetOccultationSVGOptions(options); err != nil {
return nil, err
}
events, err := moon.FindPlanetOccultations(
start, end, planet, longitude, latitude, height, searchOptions,
)
if err != nil {
return nil, err
}
diagrams := make([]string, 0, len(events))
for _, event := range events {
diagram, renderErr := LocalPlanetOccultationSVG(event, options)
if renderErr != nil {
return nil, renderErr
}
diagrams = append(diagrams, diagram)
}
return diagrams, nil
}
// LocalPlanetOccultationSVG 渲染已求解的固定地点行星月掩的月心轨迹及适用的 C1-C4 阶段面板；不会运行事件搜索。
// LocalPlanetOccultationSVG renders an already solved fixed-site planetary occultation as a Moon-centered track with all applicable C1-C4 stage panels. It does not run the event search.
func LocalPlanetOccultationSVG(
info moon.PlanetOccultationInfo,
options LocalPlanetOccultationSVGOptions,
) (string, error) {
if err := validateLocalPlanetOccultationInfo(info); err != nil {
return "", err
}
if err := validateLocalPlanetOccultationSVGOptions(options); err != nil {
return "", err
}
options = normalizeLocalPlanetOccultationSVGOptions(options)
diagram := moon.PlanetOccultationDiagram(info, moon.PlanetOccultationDiagramOptions{
StepDays: options.Step.Hours() / 24,
})
if len(diagram.Frames) == 0 {
return "", fmt.Errorf("%w: diagram geometry is unavailable", ErrInvalidLocalPlanetOccultationInfo)
}
return renderLocalPlanetOccultationSVG(info, diagram, options), nil
}
func validateLocalPlanetOccultationSVGOptions(options LocalPlanetOccultationSVGOptions) error {
if options.Width > 0 && options.Width < localPlanetOccultationSVGMinimumWidth {
return fmt.Errorf("%w: width must be zero or at least %d", ErrInvalidLocalPlanetOccultationSVGOptions, localPlanetOccultationSVGMinimumWidth)
}
if options.Height > 0 && options.Height < localPlanetOccultationSVGMinimumHeight {
return fmt.Errorf("%w: height must be zero or at least %d", ErrInvalidLocalPlanetOccultationSVGOptions, localPlanetOccultationSVGMinimumHeight)
}
if options.Step < 0 {
return fmt.Errorf("%w: step cannot be negative", ErrInvalidLocalPlanetOccultationSVGOptions)
}
return nil
}
func validateLocalPlanetOccultationInfo(info moon.PlanetOccultationInfo) error {
if err := info.Planet.Validate(); err != nil {
return fmt.Errorf("%w: %v", ErrInvalidLocalPlanetOccultationInfo, err)
}
if err := info.Observer.Validate(); err != nil {
return fmt.Errorf("%w: %v", ErrInvalidLocalPlanetOccultationInfo, err)
}
if !info.ContactsComplete || info.ExternalImmersion.IsZero() || info.Greatest.IsZero() || info.ExternalEmersion.IsZero() {
return fmt.Errorf("%w: complete external contacts and greatest time are required", ErrInvalidLocalPlanetOccultationInfo)
}
if info.Greatest.Before(info.ExternalImmersion) || info.ExternalEmersion.Before(info.Greatest) {
return fmt.Errorf("%w: event times must be ordered", ErrInvalidLocalPlanetOccultationInfo)
}
if info.Type == moon.OccultationTotal {
if !info.HasInternalContacts || info.InternalImmersion.IsZero() || info.InternalEmersion.IsZero() ||
!info.InternalImmersion.After(info.ExternalImmersion) || !info.InternalImmersion.Before(info.Greatest) ||
!info.InternalEmersion.After(info.Greatest) || !info.InternalEmersion.Before(info.ExternalEmersion) {
return fmt.Errorf("%w: a total event requires ordered C2 and C3 contacts", ErrInvalidLocalPlanetOccultationInfo)
}
} else if info.Type != moon.OccultationPartial && info.Type != moon.OccultationGrazing {
return fmt.Errorf("%w: unsupported finite-disk geometry %q", ErrInvalidLocalPlanetOccultationInfo, info.Type)
} else if info.HasInternalContacts || !info.InternalImmersion.IsZero() || !info.InternalEmersion.IsZero() {
return fmt.Errorf("%w: partial and grazing events cannot contain internal contacts", ErrInvalidLocalPlanetOccultationInfo)
}
if !starOccultationFinite(info.MinimumSeparationArcsec) || info.MinimumSeparationArcsec < 0 ||
!starOccultationFinite(info.MoonSemidiameterArcsec) || info.MoonSemidiameterArcsec <= 0 ||
!starOccultationFinite(info.PlanetSemidiameterArcsec) || info.PlanetSemidiameterArcsec <= 0 ||
info.PlanetSemidiameterArcsec >= info.MoonSemidiameterArcsec ||
!starOccultationFinite(info.PositionAngleDeg) ||
!starOccultationFinite(info.MoonAltitudeAtGreatest) ||
!starOccultationFinite(info.MoonAzimuthAtGreatest) {
return fmt.Errorf("%w: event geometry must be finite", ErrInvalidLocalPlanetOccultationInfo)
}
return nil
}
func normalizeLocalPlanetOccultationSVGOptions(options LocalPlanetOccultationSVGOptions) LocalPlanetOccultationSVGOptions {
if options.Width <= 0 {
options.Width = localPlanetOccultationSVGDefaultWidth
}
if options.Height <= 0 {
options.Height = localPlanetOccultationSVGDefaultHeight
}
if options.Step <= 0 {
options.Step = localPlanetOccultationSVGDefaultStep
}
if options.Location == nil {
options.Location = time.FixedZone("UTC+8", starOccultationSVGDefaultZone)
}
if strings.EqualFold(options.Language, starOccultationSVGLanguageEnglish) {
options.Language = starOccultationSVGLanguageEnglish
} else {
options.Language = starOccultationSVGLanguageChinese
}
return options
}
func renderLocalPlanetOccultationSVG(
info moon.PlanetOccultationInfo,
diagram moon.PlanetOccultationDiagramResult,
options LocalPlanetOccultationSVGOptions,
) string {
title := localPlanetOccultationSVGTitle(info, options)
headerLines := localPlanetOccultationSVGHeaderLines(info, options)
headerBottom := 72.0 + float64(len(headerLines))*19
layout := localPlanetOccultationSVGLayoutFor(options, headerBottom)
events := localPlanetOccultationSVGEventFrames(info, diagram.Frames, options.Language)
var b strings.Builder
fmt.Fprintf(&b, ``)
return b.String()
}
func localPlanetOccultationSVGLayoutFor(
options LocalPlanetOccultationSVGOptions,
headerBottom float64,
) localStarOccultationSVGLayout {
width := float64(options.Width)
height := float64(options.Height)
margin := math.Max(34, math.Min(44, width*0.045))
gap := math.Max(18, math.Min(24, width*0.025))
panelWidth := math.Max(210, math.Min(258, width*0.25))
overviewLeft := margin
overviewRight := width - margin - panelWidth - gap
footerSpace := 88.0
stageHeight := math.Max(156, math.Min(190, height*0.25))
stageBottom := height - footerSpace
stageTop := stageBottom - stageHeight
overviewTop := headerBottom + 26
overviewBottom := stageTop - 20
return localStarOccultationSVGLayout{
width: width,
height: height,
margin: margin,
overviewLeft: overviewLeft,
overviewRight: overviewRight,
overviewTop: overviewTop,
overviewBottom: overviewBottom,
panelX: overviewRight + gap,
panelWidth: panelWidth,
stageTop: stageTop,
stageBottom: stageBottom,
footerY: height - 62,
}
}
func writeLocalPlanetOccultationOverview(
b *strings.Builder,
diagram moon.PlanetOccultationDiagramResult,
events []localPlanetOccultationEventFrame,
layout localStarOccultationSVGLayout,
options LocalPlanetOccultationSVGOptions,
) {
fmt.Fprintf(b, `%s`,
layout.overviewLeft, layout.overviewTop-10, html.EscapeString(localPlanetOccultationSVGOverviewTitle(options)))
cx := (layout.overviewLeft + layout.overviewRight) / 2
cy := (layout.overviewTop+layout.overviewBottom)/2 + 4
extent := localPlanetOccultationSVGExtent(diagram.Frames)
availableWidth := layout.overviewRight - layout.overviewLeft - 74
availableHeight := layout.overviewBottom - layout.overviewTop - 50
scale := math.Min(availableWidth/(2*extent), availableHeight/(2*extent))
if !starOccultationFinite(scale) || scale <= 0 {
scale = 1
}
mapX := func(value float64) float64 { return cx - value*scale }
mapY := func(value float64) float64 { return cy - value*scale }
moonRadius := localPlanetOccultationSVGMaximumMoonRadius(diagram.Frames) * scale
writeLocalStarOccultationAxes(b, cx, cy, moonRadius, options.Language)
writeLocalPlanetOccultationLunarPath(b, diagram.Frames, mapX, mapY, extent, options.Language)
writeLocalPlanetOccultationTrack(b, diagram.Frames, mapX, mapY)
for _, event := range events {
writeLocalPlanetOccultationDisk(b,
mapX(event.frame.PlanetXArcsec), mapY(event.frame.PlanetYArcsec),
event.frame.PlanetRadiusArcsec*scale, false, "overview-planet-disk", event.label,
)
}
writeLocalStarOccultationMoon(b, cx, cy, moonRadius, "overview-moon")
for _, event := range events {
x := mapX(event.frame.PlanetXArcsec)
y := mapY(event.frame.PlanetYArcsec)
if event.hidden {
writeLocalPlanetOccultationDisk(b, x, y, event.frame.PlanetRadiusArcsec*scale, true, "overview-planet-outline", event.label)
}
if event.label != "C2" && event.label != "C3" {
writeLocalPlanetOccultationOverviewLabel(b, event, x, y, cx, cy)
}
}
}
func localPlanetOccultationSVGExtent(frames []moon.PlanetOccultationDiagramFrame) float64 {
extent := 1.0
for _, frame := range frames {
extent = math.Max(extent, frame.MoonRadiusArcsec)
extent = math.Max(extent, math.Abs(frame.PlanetXArcsec)+frame.PlanetRadiusArcsec)
extent = math.Max(extent, math.Abs(frame.PlanetYArcsec)+frame.PlanetRadiusArcsec)
}
return extent * 1.28
}
func localPlanetOccultationSVGMaximumMoonRadius(frames []moon.PlanetOccultationDiagramFrame) float64 {
radius := 1.0
for _, frame := range frames {
radius = math.Max(radius, frame.MoonRadiusArcsec)
}
return radius
}
func writeLocalPlanetOccultationTrack(
b *strings.Builder,
frames []moon.PlanetOccultationDiagramFrame,
mapX, mapY func(float64) float64,
) {
if len(frames) < 2 {
return
}
var path strings.Builder
for index, frame := range frames {
command := "L"
if index == 0 {
command = "M"
}
fmt.Fprintf(&path, "%s %.3f %.3f ", command, mapX(frame.PlanetXArcsec), mapY(frame.PlanetYArcsec))
}
fmt.Fprintf(b, ``, strings.TrimSpace(path.String()))
}
func writeLocalPlanetOccultationLunarPath(
b *strings.Builder,
frames []moon.PlanetOccultationDiagramFrame,
mapX, mapY func(float64) float64,
extent float64,
language string,
) {
unitX, unitY, ok := localPlanetOccultationSVGLunarPathDirection(frames)
if !ok {
return
}
lineExtent := extent * 0.92
startX := mapX(-unitX * lineExtent)
startY := mapY(-unitY * lineExtent)
endX := mapX(unitX * lineExtent)
endY := mapY(unitY * lineExtent)
if !starOccultationFinite(startX) || !starOccultationFinite(startY) ||
!starOccultationFinite(endX) || !starOccultationFinite(endY) {
return
}
fmt.Fprintf(b, ``,
startX, startY, endX, endY)
labelX, labelY := startX, startY
if endX < startX {
labelX, labelY = endX, endY
}
fmt.Fprintf(b, `%s`,
labelX-6, labelY-6, html.EscapeString(localStarOccultationSVGLunarPathLabel(language)))
}
func localPlanetOccultationSVGLunarPathDirection(frames []moon.PlanetOccultationDiagramFrame) (float64, float64, bool) {
if len(frames) < 2 {
return 0, 0, false
}
greatest := -1
for index, frame := range frames {
if localPlanetOccultationSVGFrameHasLabel(frame, "Greatest") {
greatest = index
break
}
}
left, right := 0, len(frames)-1
if greatest > 0 && greatest+1 < len(frames) {
left, right = greatest-1, greatest+1
} else if greatest == 0 {
left, right = 0, 1
} else if greatest == len(frames)-1 {
left, right = len(frames)-2, len(frames)-1
}
dx := frames[right].PlanetXArcsec - frames[left].PlanetXArcsec
dy := frames[right].PlanetYArcsec - frames[left].PlanetYArcsec
length := math.Hypot(dx, dy)
if !starOccultationFinite(length) || length == 0 {
return 0, 0, false
}
return dx / length, dy / length, true
}
func writeLocalPlanetOccultationDisk(
b *strings.Builder,
x, y, radius float64,
hidden bool,
class, label string,
) {
fill, stroke, dash := "#d6ad69", "#704b2d", ""
if hidden {
fill, stroke, dash = "none", "#7d3430", ` stroke-dasharray="2 2"`
}
fmt.Fprintf(b, ``,
html.EscapeString(class), html.EscapeString(label), x, y, math.Max(radius, 0.15), fill, stroke, dash)
}
func writeLocalPlanetOccultationOverviewLabel(
b *strings.Builder,
event localPlanetOccultationEventFrame,
x, y, cx, cy float64,
) {
dx, dy, anchor := 8.0, -9.0, "start"
if x > cx {
dx, anchor = -8, "end"
}
if y < cy-20 {
dy = 15
}
fmt.Fprintf(b, `%s`,
x+dx, y+dy, anchor, html.EscapeString(event.name))
}
func writeLocalPlanetOccultationContacts(
b *strings.Builder,
events []localPlanetOccultationEventFrame,
layout localStarOccultationSVGLayout,
options LocalPlanetOccultationSVGOptions,
) {
fmt.Fprintf(b, ``,
layout.panelX-12, layout.overviewTop-12, layout.panelX-12, layout.overviewBottom)
fmt.Fprintf(b, `%s`,
layout.panelX, layout.overviewTop-10, html.EscapeString(localPlanetOccultationSVGContactsTitle(options)))
available := layout.overviewBottom - layout.overviewTop - 10
rowHeight := math.Min(66, available/math.Max(1, float64(len(events))))
for index, event := range events {
y := layout.overviewTop + 16 + float64(index)*rowHeight
if index > 0 {
fmt.Fprintf(b, ``,
layout.panelX, y-12, layout.panelX+layout.panelWidth, y-12)
}
fmt.Fprintf(b, `%s`,
layout.panelX, y, html.EscapeString(event.name))
fmt.Fprintf(b, `%s`,
layout.panelX+layout.panelWidth, y, html.EscapeString(event.time.In(options.Location).Format("15:04:05.0")))
fmt.Fprintf(b, `PA %.1f° | %s %.1f° | %s %.1f°`,
layout.panelX, y+16, event.frame.PositionAngleDeg,
localStarOccultationSVGAltitudeLabel(options.Language), event.frame.MoonAltitudeDeg,
localStarOccultationSVGAzimuthLabel(options.Language), event.frame.MoonAzimuthDeg)
fmt.Fprintf(b, `r %.2f″ | %s`,
layout.panelX, y+31, event.frame.PlanetRadiusArcsec,
html.EscapeString(localStarOccultationSVGVisibilityText(event.frame.MoonAltitudeDeg >= 0, options.Language)))
}
}
func writeLocalPlanetOccultationStages(
b *strings.Builder,
events []localPlanetOccultationEventFrame,
layout localStarOccultationSVGLayout,
options LocalPlanetOccultationSVGOptions,
) {
fmt.Fprintf(b, `%s`,
layout.margin, layout.stageTop+13, html.EscapeString(localPlanetOccultationSVGPhasePanelsTitle(options)))
if len(events) == 0 {
return
}
usableWidth := layout.width - 2*layout.margin
columnWidth := usableWidth / float64(len(events))
maxMoonRadius := localPlanetOccultationSVGMaximumMoonRadiusFromEvents(events)
radius := math.Min(43, math.Max(31, (layout.stageBottom-layout.stageTop-59)/2))
scale := radius / maxMoonRadius
cy := layout.stageTop + 35 + radius
for index, event := range events {
cx := layout.margin + columnWidth*(float64(index)+0.5)
trueRadius := event.frame.PlanetRadiusArcsec * scale
displayRadius := math.Max(trueRadius, 5.5)
magnification := displayRadius / math.Max(trueRadius, 1e-9)
x, y := localPlanetOccultationSVGStageCenter(event, cx, cy, radius, displayRadius, scale)
fmt.Fprintf(b, ``,
html.EscapeString(event.label), trueRadius, magnification, x, y, displayRadius)
writeLocalStarOccultationMoon(b, cx, cy, event.frame.MoonRadiusArcsec*scale, "stage-moon")
if event.hidden {
fmt.Fprintf(b, ``,
x, y, displayRadius)
}
fmt.Fprintf(b, `%s`,
cx, cy+radius+18, html.EscapeString(event.name))
fmt.Fprintf(b, `%s`,
cx, cy+radius+32, html.EscapeString(event.time.In(options.Location).Format("15:04:05.0")))
}
}
// 阶段面板会放大较小的行星盘面以便观察，并在接触时同步移动显示中心，使 C1/C4 仍外切、C2/C3 仍内切。这只影响展示；事件时刻和总览使用未修改的站心几何。
// The stage panels enlarge small planet disks for visibility and move the display center by the same amount at contacts so C1/C4 remain externally tangent and C2/C3 remain internally tangent. This only affects presentation; event times and the overview use the unmodified topocentric geometry.
func localPlanetOccultationSVGStageCenter(
event localPlanetOccultationEventFrame,
cx, cy, moonRadius, displayRadius, scale float64,
) (float64, float64) {
distance := event.frame.SeparationArcsec * scale
switch event.label {
case "C1", "C4":
distance = moonRadius + displayRadius
case "C2", "C3":
distance = math.Max(0, moonRadius-displayRadius)
}
angle := event.frame.PositionAngleDeg * math.Pi / 180
return cx - distance*math.Sin(angle), cy - distance*math.Cos(angle)
}
func localPlanetOccultationSVGMaximumMoonRadiusFromEvents(events []localPlanetOccultationEventFrame) float64 {
radius := 1.0
for _, event := range events {
radius = math.Max(radius, event.frame.MoonRadiusArcsec)
}
return radius
}
func writeLocalPlanetOccultationFooter(
b *strings.Builder,
info moon.PlanetOccultationInfo,
layout localStarOccultationSVGLayout,
options LocalPlanetOccultationSVGOptions,
) {
directionLines := starOccultationWrapText(localPlanetOccultationSVGDirectionText(options), layout.width-80, 10)
for index, line := range directionLines {
fmt.Fprintf(b, `%s`,
layout.margin, layout.footerY+float64(index)*14-8, html.EscapeString(line))
}
footerLines := starOccultationWrapText(localPlanetOccultationSVGFooterNote(info, options), layout.width-80, 9)
for index, line := range footerLines {
fmt.Fprintf(b, `%s`,
layout.margin, layout.footerY+float64(len(directionLines))*14+float64(index)*12-6, html.EscapeString(line))
}
}
func localPlanetOccultationSVGEventFrames(
info moon.PlanetOccultationInfo,
frames []moon.PlanetOccultationDiagramFrame,
language string,
) []localPlanetOccultationEventFrame {
times := map[string]time.Time{
"C1": info.ExternalImmersion,
"C2": info.InternalImmersion,
"Greatest": info.Greatest,
"C3": info.InternalEmersion,
"C4": info.ExternalEmersion,
}
labels := []string{"C1", "Greatest", "C4"}
if info.HasInternalContacts {
labels = []string{"C1", "C2", "Greatest", "C3", "C4"}
}
result := make([]localPlanetOccultationEventFrame, 0, len(labels))
for _, label := range labels {
for _, frame := range frames {
if localPlanetOccultationSVGFrameHasLabel(frame, label) {
hidden := frame.FullyOcculted || info.Type == moon.OccultationTotal &&
(label == "C2" || label == "Greatest" || label == "C3")
result = append(result, localPlanetOccultationEventFrame{
label: label,
name: localPlanetOccultationSVGEventName(label, language),
time: times[label],
hidden: hidden,
frame: frame,
})
break
}
}
}
return result
}
func localPlanetOccultationSVGFrameHasLabel(frame moon.PlanetOccultationDiagramFrame, label string) bool {
if frame.Label == label {
return true
}
for _, current := range frame.Labels {
if current == label {
return true
}
}
return false
}
func localPlanetOccultationSVGHeaderLines(
info moon.PlanetOccultationInfo,
options LocalPlanetOccultationSVGOptions,
) []string {
lines := make([]string, 0, 4)
for _, value := range []string{
localPlanetOccultationSVGSummaryText(info, options),
localPlanetOccultationSVGGreatestText(info, options),
} {
lines = append(lines, starOccultationWrapText(value, float64(options.Width)-80, 13)...)
}
return lines
}
func localPlanetOccultationSVGTargetName(
info moon.PlanetOccultationInfo,
language string,
) string {
target := strings.TrimSpace(info.TargetID)
if language == starOccultationSVGLanguageChinese && (target == "" || target == info.Planet.String()) {
return planetOccultationChineseName(info.Planet)
}
if target != "" {
return target
}
if language == starOccultationSVGLanguageEnglish {
return info.Planet.String()
}
return "行星"
}
func localPlanetOccultationSVGTitle(
info moon.PlanetOccultationInfo,
options LocalPlanetOccultationSVGOptions,
) string {
if options.Title != "" {
return options.Title
}
date := info.Greatest.In(options.Location).Format("2006-01-02")
target := localPlanetOccultationSVGTargetName(info, options.Language)
if options.Language == starOccultationSVGLanguageEnglish {
return fmt.Sprintf("%s Local Lunar Occultation of %s", date, target)
}
return fmt.Sprintf("%s 指定地点月掩%s", date, target)
}
func localPlanetOccultationSVGSummaryText(
info moon.PlanetOccultationInfo,
options LocalPlanetOccultationSVGOptions,
) string {
if options.SummaryText != "" {
return options.SummaryText
}
coordinates := starOccultationFormatCoordinates(info.Observer.Longitude, info.Observer.Latitude)
duration := localStarOccultationSVGFormatDuration(info.ExternalEmersion.Sub(info.ExternalImmersion), options.Language)
if options.Language == starOccultationSVGLanguageEnglish {
return fmt.Sprintf("Site %s | elevation %.0f m | %s | C1-C4 duration %s", coordinates, info.Observer.Height,
localPlanetOccultationSVGTypeName(info.Type, options.Language), duration)
}
return fmt.Sprintf("观测点 %s | 海拔 %.0f 米 | %s | C1-C4 历时 %s", coordinates, info.Observer.Height,
localPlanetOccultationSVGTypeName(info.Type, options.Language), duration)
}
func localPlanetOccultationSVGGreatestText(
info moon.PlanetOccultationInfo,
options LocalPlanetOccultationSVGOptions,
) string {
if options.GreatestText != "" {
return options.GreatestText
}
value := info.Greatest.In(options.Location)
zone := starOccultationLocationLabel(value, options.Location)
if options.Language == starOccultationSVGLanguageEnglish {
return fmt.Sprintf("Greatest %s %s | separation %.2f arcsec | radii Moon %.2f / planet %.2f arcsec | Moon altitude %+.1f°",
value.Format("2006-01-02 15:04:05.0"), zone, info.MinimumSeparationArcsec,
info.MoonSemidiameterArcsec, info.PlanetSemidiameterArcsec, info.MoonAltitudeAtGreatest)
}
return fmt.Sprintf("掩甚 %s %s | 中心角距 %.2f 角秒 | 视半径 月 %.2f / 行星 %.2f 角秒 | 月球高度 %+.1f°",
value.Format("2006-01-02 15:04:05.0"), zone, info.MinimumSeparationArcsec,
info.MoonSemidiameterArcsec, info.PlanetSemidiameterArcsec, info.MoonAltitudeAtGreatest)
}
func localPlanetOccultationSVGOverviewTitle(options LocalPlanetOccultationSVGOptions) string {
if options.OverviewTitle != "" {
return options.OverviewTitle
}
if options.Language == starOccultationSVGLanguageEnglish {
return "Topocentric planet track (true disk scale)"
}
return "站心行星轨迹（圆盘真实比例）"
}
func localPlanetOccultationSVGPhasePanelsTitle(options LocalPlanetOccultationSVGOptions) string {
if options.PhasePanelsTitle != "" {
return options.PhasePanelsTitle
}
if options.Language == starOccultationSVGLanguageEnglish {
return "C1-C4 contact stages (planet disk enlarged)"
}
return "C1-C4 接触阶段（行星圆盘放大示意）"
}
func localPlanetOccultationSVGContactsTitle(options LocalPlanetOccultationSVGOptions) string {
if options.ContactsTitle != "" {
return options.ContactsTitle
}
if options.Language == starOccultationSVGLanguageEnglish {
return "Local contacts"
}
return "本地接触时刻"
}
func localPlanetOccultationSVGDirectionText(options LocalPlanetOccultationSVGOptions) string {
if options.DirectionText != "" {
return options.DirectionText
}
if options.Language == starOccultationSVGLanguageEnglish {
return "Moon fixed at center; east is left and north is up. Blue-gray dashed: local lunar path. Red dashed: planet-center track."
}
return "月球固定在中心；图上左东右西，向上为北。灰蓝虚线为掩甚附近的站心白道，红色虚线为行星中心相对月心轨迹。"
}
func localPlanetOccultationSVGFooterNote(
info moon.PlanetOccultationInfo,
options LocalPlanetOccultationSVGOptions,
) string {
if options.FooterNote != "" {
return options.FooterNote
}
ringNote := ""
if info.Planet == moon.OccultationSaturn {
if options.Language == starOccultationSVGLanguageEnglish {
ringNote = " Saturn's rings are excluded from contact calculation and drawing."
} else {
ringNote = "土星环不参与接触计算，也不作为圆盘边界绘制。"
}
}
if options.Language == starOccultationSVGLanguageEnglish {
return "C1/C4 are external contacts; C2/C3 are internal contacts. Stage disks are enlarged for visibility; contact times use true topocentric radii." + ringNote
}
return "C1/C4 为外切，C2/C3 为内切。阶段图中的行星圆盘为可见性放大，接触时刻按真实站心视半径求解。" + ringNote
}
func localPlanetOccultationSVGEventName(label, language string) string {
if language == starOccultationSVGLanguageEnglish {
switch label {
case "C1":
return "C1 external ingress"
case "C2":
return "C2 internal ingress"
case "Greatest":
return "Greatest"
case "C3":
return "C3 internal egress"
case "C4":
return "C4 external egress"
}
}
switch label {
case "C1":
return "C1 外切始"
case "C2":
return "C2 内切始"
case "Greatest":
return "掩甚"
case "C3":
return "C3 内切终"
case "C4":
return "C4 外切终"
default:
return label
}
}
func localPlanetOccultationSVGTypeName(eventType moon.OccultationType, language string) string {
if language == starOccultationSVGLanguageEnglish {
switch eventType {
case moon.OccultationTotal:
return "total occultation"
case moon.OccultationPartial:
return "partial occultation"
default:
return "grazing occultation"
}
}
switch eventType {
case moon.OccultationTotal:
return "行星圆面全掩"
case moon.OccultationPartial:
return "行星圆面部分掩"
default:
return "行星圆面擦边"
}
}