1 files changed, 283 insertions, 0 deletions
diff --git a/internal/render/render.go b/internal/render/render.go
new file mode 100644
index 0000000..4417763
--- /dev/null
+++ b/internal/render/render.go
@@ -0,0 +1,283 @@
+// Package render turns fetched weather into terminal output. It is pure: no
+// network, no clock beyond what it is given, so every rule below is testable.
+package render
+
+import (
+	"fmt"
+	"math"
+	"strings"
+
+	"github.com/lukaszkasprzak/prognosis/internal/config"
+	"github.com/lukaszkasprzak/prognosis/internal/i18n"
+	"github.com/lukaszkasprzak/prognosis/internal/imgw"
+	"github.com/lukaszkasprzak/prognosis/internal/openmeteo"
+)
+
+// RainInterestPct is the chance of rain below which the mm and rain columns are
+// hidden: on a dry day they are a block of zeroes that pushes real content
+// sideways.
+const RainInterestPct = 20
+
+// View is everything one run needs to render.
+type View struct {
+	Label      string
+	TZ         string
+	Rows       []openmeteo.Row
+	Sun        map[string][2]string
+	Daily      map[string]float64
+	Pollen     map[string]float64
+	Warnings   []imgw.Warning
+	WarnNote   string
+	WarnFailed bool
+}
+
+type ctx struct {
+	cfg   config.Config
+	cat   *i18n.Catalog
+	c     func(string, string) string
+	width int
+	wet   bool
+}
+
+// celsius converts a displayed temperature back to Celsius.
+//
+// IMGW's thresholds are defined in Celsius, so they must be compared in
+// Celsius: a warning threshold does not move because the display was switched
+// to Fahrenheit. Without this, 85F (a mild 29C) renders in the "IMGW would warn
+// about this" red.
+func (x ctx) celsius(v float64) float64 {
+	if x.cfg.Units == "imperial" {
+		return (v - 32) * 5 / 9
+	}
+	return v
+}
+
+// Render produces the whole output.
+func Render(v View, cfg config.Config, width int, colour bool) string {
+	cx := ctx{
+		cfg:   cfg,
+		cat:   i18n.For(cfg.DisplayLang),
+		c:     Styler(colour),
+		width: width,
+		wet:   isWet(v.Rows),
+	}
+	var out []string
+	out = append(out, cx.warnings(v)...)
+	out = append(out, cx.header(v)...)
+	out = append(out, cx.table(v)...)
+	if cfg.Graph {
+		out = append(out, cx.chart(v)...)
+	}
+	text := strings.Join(out, "\n")
+	// Applied last, one character for one, so the layout above is unaffected.
+	if cfg.ASCII {
+		text = ASCII(text, cfg.Units)
+	}
+	return text
+}
+
+func isWet(rows []openmeteo.Row) bool {
+	for _, r := range rows {
+		if mm, ok := r.Val("precipitation"); ok && mm > 0 {
+			return true
+		}
+		if p, ok := r.Val("precipitation_probability"); ok && p >= RainInterestPct {
+			return true
+		}
+	}
+	return false
+}
+
+// warnings renders IMGW warnings, or an explicit line saying why none are shown.
+//
+// WarnFailed must never look the same as "none in force": silence would be read
+// as all-clear.
+func (x ctx) warnings(v View) []string {
+	var out []string
+	switch {
+	case x.WarnDisabled():
+		return nil
+	case v.WarnFailed:
+		out = append(out, x.c(Dim, " "+x.cat.Word("warnings")+": "+x.cat.Word("could_not_check")))
+	case v.WarnNote != "":
+		out = append(out, x.c(Dim, " "+x.cat.Word("warnings")+": "+v.WarnNote))
+	}
+	for _, w := range v.Warnings {
+		style := Yellow
+		switch w.Level {
+		case "2":
+			style = Red
+		case "3":
+			style = Bold + ";" + Red
+		}
+		head := fmt.Sprintf(" ! %s  %s %s  %s -> %s  (%s%%)",
+			w.Event, x.cat.Word("level"), w.Level,
+			clip(w.From), clip(w.To), w.Probability)
+		out = append(out, x.c(style, head))
+		for _, line := range wrap(w.Text, x.width) {
+			out = append(out, x.c(Dim, "   "+line))
+		}
+	}
+	if len(out) > 0 {
+		out = append(out, "")
+	}
+	return out
+}
+
+// WarnDisabled reports whether warnings were switched off in config.
+func (x ctx) WarnDisabled() bool { return !x.cfg.Warnings }
+
+// clip shortens "2026-08-10 11:00:00" to "08-10 11:00".
+func clip(s string) string {
+	if len(s) >= 16 {
+		return s[5:16]
+	}
+	return s
+}
+
+func (x ctx) header(v View) []string {
+	var out []string
+	first := v.Rows[0].When
+	title := v.Label + "   " + x.cat.Date(first)
+	if x.cfg.Minimal {
+		// Just the place and the date: no sun times, no summary, no pollen.
+		return append(out, x.c(Bold, title))
+	}
+	sun, hasSun := v.Sun[first.Format("2006-01-02")]
+	suffix := ""
+	if hasSun {
+		suffix = fmt.Sprintf("   %s %s  %s %s",
+			sun[0], x.cat.Word("up"), sun[1], x.cat.Word("down"))
+	}
+	tz := ""
+	if v.TZ != "" {
+		tz = "  " + v.TZ
+	}
+	// Keep it to one line where it fits; a phone is narrow enough that it often
+	// does not, and a wrapped title reads worse than two deliberate lines.
+	if hasSun && DisplayWidth(title)+DisplayWidth(suffix)+DisplayWidth(tz) <= x.width {
+		out = append(out, x.c(Bold, title)+x.c(Dim, suffix+tz))
+	} else {
+		out = append(out, x.c(Bold, title)+x.c(Dim, tz))
+		if hasSun {
+			out = append(out, x.c(Dim, fmt.Sprintf(" %s  %s %s   %s %s",
+				x.cat.Word("sun"), sun[0], x.cat.Word("up"), sun[1], x.cat.Word("down"))))
+		}
+	}
+
+	if len(v.Daily) > 0 {
+		var bits []string
+		lo, okLo := v.Daily["temperature_2m_min"]
+		hi, okHi := v.Daily["temperature_2m_max"]
+		if okLo && okHi {
+			bits = append(bits, fmt.Sprintf("%d-%d°", Deg(lo), Deg(hi)))
+		}
+		if mm, ok := v.Daily["precipitation_sum"]; ok {
+			if mm == 0 {
+				bits = append(bits, x.cat.Word("dry"))
+			} else {
+				bits = append(bits, fmt.Sprintf("%s %.1fmm %s %.0fh",
+					x.cat.Word("rainfall"), mm, x.cat.Word("over"),
+					v.Daily["precipitation_hours"]))
+			}
+		}
+		if sun, ok := v.Daily["sunshine_duration"]; ok {
+			if day, ok2 := v.Daily["daylight_duration"]; ok2 {
+				bits = append(bits, fmt.Sprintf("%s %s %s %s %s",
+					x.cat.Word("sun"), hm(sun), x.cat.Word("of"), hm(day),
+					x.cat.Word("daylight")))
+			}
+		}
+		label := " " + Pad(x.cat.Word("day"), 6) + " "
+		// Joined with wide separators when it fits; only a line too long for the
+		// terminal is re-wrapped, and then on single spaces.
+		joined := strings.Join(bits, "   ")
+		lines := []string{joined}
+		if DisplayWidth(label)+DisplayWidth(joined) > x.width {
+			lines = wrap(joined, x.width-DisplayWidth(label))
+		}
+		for i, line := range lines {
+			prefix := label
+			if i > 0 {
+				prefix = strings.Repeat(" ", DisplayWidth(label))
+			}
+			out = append(out, x.c(Dim, prefix+line))
+		}
+	}
+
+	if len(v.Pollen) > 0 {
+		var bits []string
+		for _, s := range sortedByValue(v.Pollen) {
+			band := PollenBand(s, v.Pollen[s])
+			// Skip taxa that are simply absent, but never hide grass: it is the
+			// one someone may be allergic to and its absence is information.
+			if band == "none" && s != "grass" {
+				continue
+			}
+			text := fmt.Sprintf("%s %.1f", x.cat.Species(s), v.Pollen[s])
+			if band != "" {
+				text += " " + x.cat.Band(band)
+			}
+			bits = append(bits, text)
+		}
+		if len(bits) > 0 {
+			if len(bits) > 4 {
+				bits = bits[:4]
+			}
+			out = append(out, x.c(Dim, " "+Pad(x.cat.Word("pollen"), 6)+" ")+strings.Join(bits, "  "))
+		}
+	}
+	return out
+}
+
+func hm(seconds float64) string {
+	s := int(seconds)
+	return fmt.Sprintf("%dh%02dm", s/3600, (s%3600)/60)
+}
+
+func sortedByValue(m map[string]float64) []string {
+	keys := make([]string, 0, len(m))
+	for k := range m {
+		keys = append(keys, k)
+	}
+	for i := 1; i < len(keys); i++ {
+		for j := i; j > 0 && m[keys[j]] > m[keys[j-1]]; j-- {
+			keys[j], keys[j-1] = keys[j-1], keys[j]
+		}
+	}
+	return keys
+}
+
+func wrap(text string, width int) []string {
+	if width < 8 {
+		width = 8
+	}
+	var lines []string
+	var line string
+	for _, word := range strings.Fields(text) {
+		switch {
+		case line == "":
+			line = word
+		case DisplayWidth(line)+1+DisplayWidth(word) <= width:
+			line += " " + word
+		default:
+			lines = append(lines, line)
+			line = word
+		}
+	}
+	if line != "" {
+		lines = append(lines, line)
+	}
+	return lines
+}
+
+func round1(v float64) string { return fmt.Sprintf("%.1f", v) }
+
+func compass(deg float64) string {
+	dirs := []string{"↓", "↙", "←", "↖", "↑", "↗", "→", "↘"}
+	i := int(math.Mod(math.Round(deg/45), 8))
+	if i < 0 {
+		i += 8
+	}
+	return dirs[i]
+}