1 files changed, 84 insertions, 0 deletions
diff --git a/internal/render/icons.go b/internal/render/icons.go
new file mode 100644
index 0000000..59ae3d3
--- /dev/null
+++ b/internal/render/icons.go
@@ -0,0 +1,84 @@
+package render
+
+// Weather glyphs per icon set, keyed by WMO code group.
+//
+// The "nerd" codepoints are from the Nerd Fonts Weather range (U+E300-U+E3E3),
+// which JetBrains Mono Nerd Font and MesloLGS NF both carry. They are single
+// cell and monochrome, so they take the terminal's foreground colour and do not
+// break a remapped palette.
+//
+// The "emoji" set is colour and comes from a fallback font. Its glyphs are not
+// all one cell wide -- see width.go -- which is why every pad goes through
+// DisplayWidth.
+var iconSets = map[string]map[string]string{
+	"nerd": {
+		"clear":   "",
+		"partly":  "",
+		"cloudy":  "",
+		"fog":     "",
+		"drizzle": "",
+		"rain":    "",
+		"snow":    "",
+		"storm":   "",
+	},
+	"emoji": {
+		"clear":   "☀",
+		"partly":  "⛅",
+		"cloudy":  "☁",
+		"fog":     "\U0001F32B",
+		"drizzle": "\U0001F326",
+		"rain":    "\U0001F327",
+		"snow":    "\U0001F328",
+		"storm":   "⛈",
+	},
+}
+
+// iconGroup maps a WMO weather code onto a glyph group.
+func iconGroup(code int) string {
+	switch {
+	case code == 0 || code == 1:
+		return "clear"
+	case code == 2:
+		return "partly"
+	case code == 3:
+		return "cloudy"
+	case code == 45 || code == 48:
+		return "fog"
+	case code >= 51 && code <= 57:
+		return "drizzle"
+	case code >= 61 && code <= 67, code >= 80 && code <= 82:
+		return "rain"
+	case code >= 71 && code <= 77, code == 85 || code == 86:
+		return "snow"
+	case code >= 95:
+		return "storm"
+	}
+	return "cloudy"
+}
+
+// Icon returns the glyph for a weather code in the named set. An unknown set,
+// or "none", yields an empty string so the column simply renders blank.
+func Icon(set string, code int) string {
+	glyphs, ok := iconSets[set]
+	if !ok {
+		return ""
+	}
+	return glyphs[iconGroup(code)]
+}
+
+// IconWidth is the display width the icon column should reserve for a set.
+// The emoji set contains wide glyphs, so its column is two cells even for the
+// entries that happen to be one.
+func IconWidth(set string) int {
+	glyphs, ok := iconSets[set]
+	if !ok {
+		return 0
+	}
+	w := 1
+	for _, g := range glyphs {
+		if gw := DisplayWidth(g); gw > w {
+			w = gw
+		}
+	}
+	return w
+}