From b9f36ee948d3b1ff71c0099f579db308fe3eba4b Mon Sep 17 00:00:00 2001
From: Brian McGee <brian@bmcgee.ie>
Date: Wed, 3 Jul 2024 19:07:36 +0100
Subject: [PATCH] feat: add batch size global config value

Signed-off-by: Brian McGee <brian@bmcgee.ie>
---
 cli/format.go              | 12 ++++++++++++
 config/config.go           |  2 ++
 config/config_test.go      |  1 +
 test/examples/treefmt.toml |  1 +
 4 files changed, 16 insertions(+)

diff --git a/cli/format.go b/cli/format.go
index da9552ea..8ceac98c 100644
--- a/cli/format.go
+++ b/cli/format.go
@@ -23,6 +23,10 @@ import (
 	"golang.org/x/sync/errgroup"
 )
 
+const (
+	DefaultBatchSize = 1024
+)
+
 var (
 	ErrFailOnChange     = errors.New("unexpected changes detected, --fail-on-change is enabled")
 	ErrInvalidBatchSize = errors.New("batch size must be >= 1")
@@ -32,6 +36,8 @@ func (f *Format) Run() (err error) {
 	// set log level and other options
 	f.configureLogging()
 
+	// validate the cli batch size
+	// todo move this into kong validation
 	if f.BatchSize < 1 {
 		return ErrInvalidBatchSize
 	}
@@ -99,6 +105,12 @@ func (f *Format) Run() (err error) {
 		return fmt.Errorf("failed to read config file %v: %w", f.ConfigFile, err)
 	}
 
+	// update the batch size only if it has not already been set by the cli arg
+	// cli arg takes precedence over config
+	if f.BatchSize == DefaultBatchSize && cfg.Global.BatchSize != 0 {
+		f.BatchSize = cfg.Global.BatchSize
+	}
+
 	// compile global exclude globs
 	if f.globalExcludes, err = format.CompileGlobs(cfg.Global.Excludes); err != nil {
 		return fmt.Errorf("failed to compile global excludes: %w", err)
diff --git a/config/config.go b/config/config.go
index 553aee62..32114388 100644
--- a/config/config.go
+++ b/config/config.go
@@ -9,6 +9,8 @@ import (
 // Config is used to represent the list of configured Formatters.
 type Config struct {
 	Global struct {
+		// BatchSize controls the maximum number of paths to batch before applying them to a sequence of formatters.
+		BatchSize int `toml:"batch_size"`
 		// Excludes is an optional list of glob patterns used to exclude certain files from all formatters.
 		Excludes []string `toml:"excludes"`
 	} `toml:"global"`
diff --git a/config/config_test.go b/config/config_test.go
index abb9344c..3a44bcf8 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -14,6 +14,7 @@ func TestReadConfigFile(t *testing.T) {
 
 	as.NotNil(cfg)
 
+	as.Equal(10, cfg.Global.BatchSize)
 	as.Equal([]string{"*.toml"}, cfg.Global.Excludes)
 
 	// python
diff --git a/test/examples/treefmt.toml b/test/examples/treefmt.toml
index 2291ca82..ab2c735d 100644
--- a/test/examples/treefmt.toml
+++ b/test/examples/treefmt.toml
@@ -1,6 +1,7 @@
 # One CLI to format the code tree - https://git.numtide.com/numtide/treefmt
 
 [global]
+batch_size = 10
 excludes = ["*.toml"]
 
 [formatter.python]