1 files changed, 65 insertions, 1 deletions

diff --git a/internal/render/table.go b/internal/render/table.go
index 3ade296..3219e9d 100644
--- a/internal/render/table.go
+++ b/internal/render/table.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/lukaszkasprzak/prognosis/internal/config"
 	"github.com/lukaszkasprzak/prognosis/internal/openmeteo"
 )
 
@@ -14,8 +15,34 @@ type cell struct {
 	left  bool
 }
 
+// custom returns the config's definition of a column, if it has one.
+func (x ctx) custom(name string) (config.CustomColumn, bool) {
+	cc, ok := x.cfg.Custom[name]
+	return cc, ok
+}
+
+// customLabel is the header for a custom column: what the user asked for, or
+// the column's own name.
+func customLabel(name string, cc config.CustomColumn) string {
+	if cc.Label != "" {
+		return cc.Label
+	}
+	return name
+}
+
 // colWidth is the reserved display width per column.
 func (x ctx) colWidth(name string) int {
+	if cc, ok := x.custom(name); ok {
+		if cc.Width > 0 {
+			return cc.Width
+		}
+		// Wide enough for the header, and for a value of a few digits.
+		w := DisplayWidth(customLabel(name, cc))
+		if w < 5 {
+			w = 5
+		}
+		return w
+	}
 	switch name {
 	case "hour":
 		// Three, not two: the Python leaves a double space after the hour.
@@ -39,6 +66,9 @@ func (x ctx) colWidth(name string) int {
 }
 
 func (x ctx) leftAligned(name string) bool {
+	if _, ok := x.custom(name); ok {
+		return false // custom columns are numeric
+	}
 	switch name {
 	case "hour", "icon", "temp", "feels", "conditions":
 		return true
@@ -86,7 +116,12 @@ func (x ctx) table(v View) []string {
 
 	headers := map[string]cell{}
 	for _, name := range x.visible() {
-		headers[name] = cell{text: x.cat.Header(name), style: ""}
+		text := x.cat.Header(name)
+		if cc, ok := x.custom(name); ok {
+			// A user-declared label is not ours to translate.
+			text = customLabel(name, cc)
+		}
+		headers[name] = cell{text: text, style: ""}
 	}
 	out = append(out, x.c(Underline, x.rowPlain(headers)))
 
@@ -129,6 +164,10 @@ func (x ctx) cells(r openmeteo.Row, isNow bool, prevCode *int) map[string]cell {
 	temp, hasTemp := r.Val("temperature_2m")
 
 	for _, name := range x.visible() {
+		if cc, ok := x.custom(name); ok {
+			out[name] = x.customCell(r, name, cc)
+			continue
+		}
 		switch name {
 		case "hour":
 			style := Reset
@@ -238,3 +277,28 @@ func abs(f float64) float64 {
 	}
 	return f
 }
+
+// CustomKey is where a custom column's value lives in a Row.
+//
+// Prefixed so a column called "temp" or "visibility" can never shadow the API
+// field of the same name that a built-in column reads.
+func CustomKey(name string) string { return "x:" + name }
+
+// customCell formats one user-declared column.
+//
+// A value the API did not supply renders blank rather than as zero: for an
+// allergen or a soil reading, "no data" and "none" are different claims.
+func (x ctx) customCell(r openmeteo.Row, name string, cc config.CustomColumn) cell {
+	key := cc.Field
+	if cc.Source == "air" {
+		key = CustomKey(name)
+	}
+	v, ok := r.Val(key)
+	if !ok {
+		return cell{text: "", style: Dim}
+	}
+	return cell{
+		text:  fmt.Sprintf("%.*f%s", cc.Decimals, v, cc.Suffix),
+		style: Dim,
+	}
+}