From 97f4793ec3d0e747d89669bfa1c4a7db98599f8d Mon Sep 17 00:00:00 2001
From: Sam Fredrickson <samfredrickson@gmail.com>
Date: Fri, 22 Mar 2024 22:54:32 -0700
Subject: [PATCH] Write errors to log file.

---
 moonmath.go        | 36 ++++++++++++++++++++++++++++++
 tui/asset/asset.go | 55 ++++++++++++++++++++++++++++++----------------
 2 files changed, 72 insertions(+), 19 deletions(-)

diff --git a/moonmath.go b/moonmath.go
index ae09603..5de23cf 100644
--- a/moonmath.go
+++ b/moonmath.go
@@ -2,7 +2,10 @@ package main
 
 import (
 	"fmt"
+	"io"
+	"log/slog"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"code.humancabbage.net/sam/moonmath/coindesk"
@@ -19,6 +22,10 @@ var CLI struct {
 }
 
 func main() {
+	logFile := setupLogging()
+	defer func() {
+		_ = logFile.Close()
+	}()
 	ctx := kong.Parse(&CLI)
 	if ctx.Error != nil {
 		fail(ctx.Error)
@@ -42,6 +49,35 @@ func main() {
 	}
 }
 
+func setupLogging() io.Closer {
+	homePath, err := os.UserHomeDir()
+	if err != nil {
+		panic(err)
+	}
+
+	programConfigPath := filepath.Join(homePath, ".moonmath")
+	err = os.MkdirAll(programConfigPath, 0755)
+	if err != nil {
+		panic(err)
+	}
+
+	errLogPath := filepath.Join(programConfigPath, "errors.log")
+	errLogFile, err := os.OpenFile(
+		errLogPath,
+		os.O_CREATE|os.O_APPEND|os.O_WRONLY,
+		0600,
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	slog.SetDefault(slog.New(
+		slog.NewTextHandler(errLogFile, &slog.HandlerOptions{
+			Level: slog.LevelError,
+		})))
+	return errLogFile
+}
+
 func fail(err error) {
 	fmt.Printf("program error: %v\n", err)
 	os.Exit(1)
diff --git a/tui/asset/asset.go b/tui/asset/asset.go
index ec98ee0..a9608d7 100644
--- a/tui/asset/asset.go
+++ b/tui/asset/asset.go
@@ -3,6 +3,7 @@ package asset
 import (
 	"context"
 	"fmt"
+	"log/slog"
 	"time"
 
 	"code.humancabbage.net/sam/moonmath/coindesk"
@@ -109,31 +110,16 @@ func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) {
 		case refresh:
 			m.refreshing = true
 			return m, tea.Batch(
-				func() tea.Msg {
-					return m.indicator.Tick()
-				},
-				func() tea.Msg {
-					// TODO: log errors
-					_ = m.math.Refresh(context.TODO())
-					return Msg{m.math.Asset, m.math}
-				},
+				m.resumeIndicator,
+				m.refresh,
 			)
 		case moon.Math:
 			m.math = msg
 			refillProperties(&m)
 			refillProjections(&m)
 			return m, tea.Batch(
-				// schedule the next refresh
-				tea.Tick(time.Second*30,
-					func(t time.Time) tea.Msg {
-						return Msg{m.math.Asset, refresh{}}
-					}),
-				// wait a bit to stop the indicator, so that it's more obvious
-				// even when the refresh completes quickly.
-				tea.Tick(time.Millisecond*500,
-					func(t time.Time) tea.Msg {
-						return Msg{m.math.Asset, stopIndicator{}}
-					}),
+				m.stopIndicator(),
+				m.scheduleRefresh(),
 			)
 		case stopIndicator:
 			m.refreshing = false
@@ -153,6 +139,37 @@ func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) {
 type refresh struct{}
 type stopIndicator struct{}
 
+func (m Model) refresh() tea.Msg {
+	err := m.math.Refresh(context.TODO())
+	if err != nil {
+		slog.Error("refresh",
+			"asset", m.math.Asset,
+			"err", err,
+		)
+	}
+	return Msg{m.math.Asset, m.math}
+}
+
+func (m Model) resumeIndicator() tea.Msg {
+	return m.indicator.Tick()
+}
+
+func (m Model) scheduleRefresh() tea.Cmd {
+	return tea.Tick(time.Second*30,
+		func(t time.Time) tea.Msg {
+			return Msg{m.math.Asset, refresh{}}
+		})
+}
+
+func (m Model) stopIndicator() tea.Cmd {
+	// wait a bit to stop the indicator, so that it's more obvious
+	// even when the refresh completes quickly.
+	return tea.Tick(time.Millisecond*500,
+		func(t time.Time) tea.Msg {
+			return Msg{m.math.Asset, stopIndicator{}}
+		})
+}
+
 func refillProperties(m *Model) {
 	rows := []table.Row{
 		{"Asset", string(m.math.Asset)},