package config

import (
	"os"
	"path/filepath"
	"testing"
)

func TestLoadValidConfig(t *testing.T) {
	dir := t.TempDir()
	cfgFile := filepath.Join(dir, "config.toml")

	content := `
issuer = "https://id.example.com/realms/test"
client_id = "nix-cache"
cache_host = "cache.example.com"
netrc_path = "/home/user/.config/nix/netrc"
`
	if err := os.WriteFile(cfgFile, []byte(content), 0644); err != nil {
		t.Fatal(err)
	}

	cfg, err := Load(cfgFile)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if cfg.Issuer != "https://id.example.com/realms/test" {
		t.Errorf("issuer = %q, want %q", cfg.Issuer, "https://id.example.com/realms/test")
	}
	if cfg.ClientID != "nix-cache" {
		t.Errorf("client_id = %q, want %q", cfg.ClientID, "nix-cache")
	}
	if cfg.CacheHost != "cache.example.com" {
		t.Errorf("cache_host = %q, want %q", cfg.CacheHost, "cache.example.com")
	}
	if cfg.ClientSecret != "" {
		t.Errorf("client_secret = %q, want empty", cfg.ClientSecret)
	}
}

func TestLoadConfigWithClientSecret(t *testing.T) {
	dir := t.TempDir()
	cfgFile := filepath.Join(dir, "config.toml")

	content := `
issuer = "https://id.example.com/realms/test"
client_id = "nix-cache-server"
client_secret = "super-secret"
cache_host = "cache.example.com"
netrc_path = "/tmp/netrc"
`
	if err := os.WriteFile(cfgFile, []byte(content), 0644); err != nil {
		t.Fatal(err)
	}

	cfg, err := Load(cfgFile)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if cfg.ClientSecret != "super-secret" {
		t.Errorf("client_secret = %q, want %q", cfg.ClientSecret, "super-secret")
	}
}

func TestEnvVarExpansionInNetrcPath(t *testing.T) {
	dir := t.TempDir()
	cfgFile := filepath.Join(dir, "config.toml")

	t.Setenv("TEST_CONFIG_DIR", "/custom/config")

	content := `
issuer = "https://id.example.com/realms/test"
client_id = "nix-cache"
cache_host = "cache.example.com"
netrc_path = "$TEST_CONFIG_DIR/nix/netrc"
`
	if err := os.WriteFile(cfgFile, []byte(content), 0644); err != nil {
		t.Fatal(err)
	}

	cfg, err := Load(cfgFile)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if cfg.NetrcPath != "/custom/config/nix/netrc" {
		t.Errorf("netrc_path = %q, want %q", cfg.NetrcPath, "/custom/config/nix/netrc")
	}
}

func TestEnvVarExpansionBraces(t *testing.T) {
	dir := t.TempDir()
	cfgFile := filepath.Join(dir, "config.toml")

	t.Setenv("MY_HOME", "/home/testuser")

	content := `
issuer = "https://id.example.com/realms/test"
client_id = "nix-cache"
cache_host = "cache.example.com"
netrc_path = "${MY_HOME}/.config/nix/netrc"
`
	if err := os.WriteFile(cfgFile, []byte(content), 0644); err != nil {
		t.Fatal(err)
	}

	cfg, err := Load(cfgFile)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if cfg.NetrcPath != "/home/testuser/.config/nix/netrc" {
		t.Errorf("netrc_path = %q, want %q", cfg.NetrcPath, "/home/testuser/.config/nix/netrc")
	}
}

func TestMissingRequiredFields(t *testing.T) {
	tests := []struct {
		name    string
		content string
		errMsg  string
	}{
		{
			name:    "missing issuer",
			content: `client_id = "x"` + "\n" + `cache_host = "x"` + "\n" + `netrc_path = "/tmp/x"`,
			errMsg:  "issuer is required",
		},
		{
			name:    "missing client_id",
			content: `issuer = "https://x"` + "\n" + `cache_host = "x"` + "\n" + `netrc_path = "/tmp/x"`,
			errMsg:  "client_id is required",
		},
		{
			name:    "missing cache_host",
			content: `issuer = "https://x"` + "\n" + `client_id = "x"` + "\n" + `netrc_path = "/tmp/x"`,
			errMsg:  "cache_host is required",
		},
		{
			name:    "missing netrc_path",
			content: `issuer = "https://x"` + "\n" + `client_id = "x"` + "\n" + `cache_host = "x"`,
			errMsg:  "netrc_path is required",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			dir := t.TempDir()
			cfgFile := filepath.Join(dir, "config.toml")
			if err := os.WriteFile(cfgFile, []byte(tt.content), 0644); err != nil {
				t.Fatal(err)
			}

			_, err := Load(cfgFile)
			if err == nil {
				t.Fatal("expected error, got nil")
			}
			if !contains(err.Error(), tt.errMsg) {
				t.Errorf("error = %q, want to contain %q", err.Error(), tt.errMsg)
			}
		})
	}
}

func contains(s, substr string) bool {
	return len(s) >= len(substr) && searchString(s, substr)
}

func searchString(s, substr string) bool {
	for i := 0; i <= len(s)-len(substr); i++ {
		if s[i:i+len(substr)] == substr {
			return true
		}
	}
	return false
}