Add configuration file support with organization list

- Create config package with JSON parsing support
- Define Organization struct with host and name
- Add config file auto-detection in common locations
- Add --config/-c flag for custom config path
- Add --list-orgs flag to display configured organizations
- Create example configuration file
- Add comprehensive .gitignore

Configuration supports multiple git organizations for future sync functionality.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

5 files changed, 207 insertions, 3 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..7101fd7
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,39 @@
+# Binaries
+gitsyncer
+gitsyncer-*
+
+# Configuration files (except examples)
+gitsyncer.json
+.gitsyncer.json
+*.json
+!*.example.json
+
+# IDE and editor files
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# Go build artifacts
+*.exe
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool
+*.out
+
+# Dependency directories
+vendor/
+
+# Go workspace file
+go.work
+go.work.sum
+
+# OS files
+.DS_Store
+Thumbs.db
\ No newline at end of file
diff --git a/cmd/gitsyncer/main.go b/cmd/gitsyncer/main.go
index 3a38d32..d859747 100644
--- a/cmd/gitsyncer/main.go
+++ b/cmd/gitsyncer/main.go
@@ -3,23 +3,93 @@ package main
 import (
 	"flag"
 	"fmt"
+	"log"
 	"os"
+	"path/filepath"
 
+	"github.com/paul/gitsyncer/internal/config"
 	"github.com/paul/gitsyncer/internal/version"
 )
 
 func main() {
-	var versionFlag bool
+	var (
+		versionFlag bool
+		configPath  string
+		listOrgs    bool
+	)
+
+	// Define command line flags
 	flag.BoolVar(&versionFlag, "version", false, "print version information")
 	flag.BoolVar(&versionFlag, "v", false, "print version information (short)")
+	flag.StringVar(&configPath, "config", "", "path to configuration file")
+	flag.StringVar(&configPath, "c", "", "path to configuration file (short)")
+	flag.BoolVar(&listOrgs, "list-orgs", false, "list configured organizations")
 	flag.Parse()
 
+	// Handle version flag
 	if versionFlag {
 		fmt.Println(version.GetVersion())
 		os.Exit(0)
 	}
 
+	// Determine config file path
+	if configPath == "" {
+		// Try default locations
+		home, err := os.UserHomeDir()
+		if err != nil {
+			log.Fatal("Failed to get home directory:", err)
+		}
+
+		// Check common config locations
+		configLocations := []string{
+			filepath.Join(".", "gitsyncer.json"),
+			filepath.Join(home, ".config", "gitsyncer", "config.json"),
+			filepath.Join(home, ".gitsyncer.json"),
+		}
+
+		for _, loc := range configLocations {
+			if _, err := os.Stat(loc); err == nil {
+				configPath = loc
+				break
+			}
+		}
+
+		if configPath == "" {
+			fmt.Println("No configuration file found. Please create one of:")
+			for _, loc := range configLocations {
+				fmt.Printf("  - %s\n", loc)
+			}
+			fmt.Println("\nOr specify a config file with --config flag")
+			fmt.Println("\nExample configuration:")
+			fmt.Println(`{
+  "organizations": [
+    {"host": "git@github.com", "name": "myorg"},
+    {"host": "git@codeberg.org", "name": "myorg"}
+  ]
+}`)
+			os.Exit(1)
+		}
+	}
+
+	// Load configuration
+	cfg, err := config.Load(configPath)
+	if err != nil {
+		log.Fatal("Failed to load configuration:", err)
+	}
+
+	fmt.Printf("Loaded configuration from: %s\n", configPath)
+
+	// Handle list organizations flag
+	if listOrgs {
+		fmt.Println("\nConfigured organizations:")
+		for _, org := range cfg.Organizations {
+			fmt.Printf("  - %s\n", org.GetGitURL())
+		}
+		os.Exit(0)
+	}
+
 	// TODO: Implement main gitsyncer functionality
-	fmt.Println("gitsyncer - Git repository synchronization tool")
-	fmt.Println("Use --version to display version information")
+	fmt.Println("\ngitsyncer - Git repository synchronization tool")
+	fmt.Printf("Configured with %d organization(s)\n", len(cfg.Organizations))
+	fmt.Println("\nUse --list-orgs to display configured organizations")
 }
\ No newline at end of file
diff --git a/gitsyncer b/gitsyncer
index 1f897cd..9134faa 100755
--- a/gitsyncer
+++ b/gitsyncer
diff --git a/gitsyncer.example.json b/gitsyncer.example.json
new file mode 100644
index 0000000..3170286
--- /dev/null
+++ b/gitsyncer.example.json
@@ -0,0 +1,12 @@
+{
+  "organizations": [
+    {
+      "host": "git@codeberg.org",
+      "name": "snonux"
+    },
+    {
+      "host": "git@github.com",
+      "name": "snonux"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/internal/config/config.go b/internal/config/config.go
new file mode 100644
index 0000000..91c107a
--- /dev/null
+++ b/internal/config/config.go
@@ -0,0 +1,83 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+// Organization represents a git organization with its host and name
+type Organization struct {
+	Host string `json:"host"`
+	Name string `json:"name"`
+}
+
+// Config holds the application configuration
+type Config struct {
+	Organizations []Organization `json:"organizations"`
+}
+
+// Load reads and parses the configuration file
+func Load(path string) (*Config, error) {
+	// Expand home directory if needed
+	if path[:2] == "~/" {
+		home, err := os.UserHomeDir()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get home directory: %w", err)
+		}
+		path = filepath.Join(home, path[2:])
+	}
+
+	// Read config file
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read config file: %w", err)
+	}
+
+	// Parse JSON
+	var cfg Config
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		return nil, fmt.Errorf("failed to parse config: %w", err)
+	}
+
+	// Validate configuration
+	if err := cfg.Validate(); err != nil {
+		return nil, fmt.Errorf("invalid configuration: %w", err)
+	}
+
+	return &cfg, nil
+}
+
+// Validate checks if the configuration is valid
+func (c *Config) Validate() error {
+	if len(c.Organizations) == 0 {
+		return fmt.Errorf("no organizations configured")
+	}
+
+	for i, org := range c.Organizations {
+		if org.Host == "" {
+			return fmt.Errorf("organization %d: missing host", i)
+		}
+		if org.Name == "" {
+			return fmt.Errorf("organization %d: missing name", i)
+		}
+	}
+
+	return nil
+}
+
+// GetGitURL returns the git URL for an organization
+func (o *Organization) GetGitURL() string {
+	return fmt.Sprintf("%s:%s", o.Host, o.Name)
+}
+
+// FindOrganization finds an organization by host
+func (c *Config) FindOrganization(host string) *Organization {
+	for _, org := range c.Organizations {
+		if org.Host == host {
+			return &org
+		}
+	}
+	return nil
+}
\ No newline at end of file