package config

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

func TestDefaults(t *testing.T) {
	d := Defaults()

	if d.Port != 8976 {
		t.Errorf("expected port 8976, got %d", d.Port)
	}
	if d.CursorCLIPath != "agent" {
		t.Errorf("expected cursor_cli_path 'agent', got %q", d.CursorCLIPath)
	}
	if d.DefaultModel != "auto" {
		t.Errorf("expected default_model 'auto', got %q", d.DefaultModel)
	}
	if d.Timeout != 300 {
		t.Errorf("expected timeout 300, got %d", d.Timeout)
	}
	if d.MaxConcurrent != 5 {
		t.Errorf("expected max_concurrent 5, got %d", d.MaxConcurrent)
	}
	if d.LogLevel != "INFO" {
		t.Errorf("expected log_level 'INFO', got %q", d.LogLevel)
	}
	if d.UseACP {
		t.Errorf("expected use_acp false by default, got true")
	}
}

func TestLoadValidYAML(t *testing.T) {
	content := `port: 9000
cursor_cli_path: mycli
default_model: gpt-5.2
timeout: 60
max_concurrent: 10
use_acp: true
log_level: DEBUG
available_models:
  - gpt-5.2
  - claude-sonnet-4-20250514
`
	dir := t.TempDir()
	path := filepath.Join(dir, "config.yaml")
	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
		t.Fatal(err)
	}

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

	want := Config{
		Port:              9000,
		CursorCLIPath:     "mycli",
		DefaultModel:      "gpt-5.2",
		Timeout:           60,
		MaxConcurrent:     10,
		UseACP:            true,
		ChatOnlyWorkspace: true,
		LogLevel:          "DEBUG",
		AvailableModels:   []string{"gpt-5.2", "claude-sonnet-4-20250514"},
		SystemPrompt:      DefaultSystemPrompt,
		CursorMode:        "plan",
		WorkspaceRoot:     "",
	}

	if !reflect.DeepEqual(*cfg, want) {
		t.Errorf("mismatch\n got: %+v\nwant: %+v", *cfg, want)
	}
}

func TestLoadMissingFile(t *testing.T) {
	path := filepath.Join(t.TempDir(), "does-not-exist.yaml")

	cfg, err := Load(path)
	if err != nil {
		t.Fatalf("expected no error for missing file, got: %v", err)
	}

	d := Defaults()
	if !reflect.DeepEqual(*cfg, d) {
		t.Errorf("expected defaults\n got: %+v\nwant: %+v", *cfg, d)
	}
}

func TestLoadInvalidYAML(t *testing.T) {
	content := `{{not valid yaml`
	dir := t.TempDir()
	path := filepath.Join(dir, "bad.yaml")
	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
		t.Fatal(err)
	}

	_, err := Load(path)
	if err == nil {
		t.Fatal("expected error for invalid YAML, got nil")
	}
}

func TestLoadValidation(t *testing.T) {
	tests := []struct {
		name    string
		yaml    string
		wantErr string
	}{
		{
			name:    "zero port",
			yaml:    "port: 0\ncursor_cli_path: agent\ntimeout: 10\n",
			wantErr: "port must be > 0",
		},
		{
			name:    "empty cursor_cli_path",
			yaml:    "port: 80\ncursor_cli_path: \"\"\ntimeout: 10\n",
			wantErr: "cursor_cli_path must not be empty",
		},
		{
			name:    "zero timeout",
			yaml:    "port: 80\ncursor_cli_path: agent\ntimeout: 0\n",
			wantErr: "timeout must be > 0",
		},
	}

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

			_, err := Load(path)
			if err == nil {
				t.Fatal("expected error, got nil")
			}
			if got := err.Error(); !contains(got, tt.wantErr) {
				t.Errorf("error %q should contain %q", got, tt.wantErr)
			}
		})
	}
}

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

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