zero/internal/config/writer.go

package config

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

func UpsertProvider(path string, profile ProviderProfile, setActive bool) (FileConfig, error) {
	path = strings.TrimSpace(path)
	if path == "" {
		return FileConfig{}, fmt.Errorf("config path is required")
	}
	profile.Name = strings.TrimSpace(profile.Name)
	if profile.Name == "" {
		return FileConfig{}, fmt.Errorf("provider name is required")
	}

	cfg := FileConfig{}
	if data, err := os.ReadFile(path); err == nil {
		if err := json.Unmarshal(data, &cfg); err != nil {
			return FileConfig{}, fmt.Errorf("invalid config JSON %s: %w", path, err)
		}
	} else if !os.IsNotExist(err) {
		return FileConfig{}, fmt.Errorf("read config %s: %w", path, err)
	}

	mergeProvider(&cfg, profile)
	if setActive || strings.TrimSpace(cfg.ActiveProvider) == "" {
		cfg.ActiveProvider = profile.Name
	}

	if err := writeConfigFile(path, cfg); err != nil {
		return FileConfig{}, err
	}
	return cfg, nil
}

func SetActiveProvider(path string, name string) (FileConfig, error) {
	path = strings.TrimSpace(path)
	if path == "" {
		return FileConfig{}, fmt.Errorf("config path is required")
	}
	name = strings.TrimSpace(name)
	if name == "" {
		return FileConfig{}, fmt.Errorf("provider name is required")
	}

	data, err := os.ReadFile(path)
	if err != nil {
		return FileConfig{}, fmt.Errorf("read config %s: %w", path, err)
	}

	cfg := FileConfig{}
	if err := json.Unmarshal(data, &cfg); err != nil {
		return FileConfig{}, fmt.Errorf("invalid config JSON %s: %w", path, err)
	}

	for _, provider := range cfg.Providers {
		if strings.EqualFold(provider.Name, name) {
			cfg.ActiveProvider = provider.Name
			if err := writeConfigFile(path, cfg); err != nil {
				return FileConfig{}, err
			}
			return cfg, nil
		}
	}

	return FileConfig{}, fmt.Errorf("provider %q not found", name)
}

func SetProviderModel(path string, name string, model string) (FileConfig, error) {
	path = strings.TrimSpace(path)
	if path == "" {
		return FileConfig{}, fmt.Errorf("config path is required")
	}
	name = strings.TrimSpace(name)
	if name == "" {
		return FileConfig{}, fmt.Errorf("provider name is required")
	}
	model = strings.TrimSpace(model)
	if model == "" {
		return FileConfig{}, fmt.Errorf("model is required")
	}

	data, err := os.ReadFile(path)
	if err != nil {
		return FileConfig{}, fmt.Errorf("read config %s: %w", path, err)
	}

	cfg := FileConfig{}
	if err := json.Unmarshal(data, &cfg); err != nil {
		return FileConfig{}, fmt.Errorf("invalid config JSON %s: %w", path, err)
	}

	for index := range cfg.Providers {
		if strings.EqualFold(cfg.Providers[index].Name, name) {
			cfg.Providers[index].Model = model
			if err := writeConfigFile(path, cfg); err != nil {
				return FileConfig{}, err
			}
			return cfg, nil
		}
	}

	return FileConfig{}, fmt.Errorf("provider %q not found", name)
}

func SetFavoriteModels(path string, models []string) (FileConfig, error) {
	path = strings.TrimSpace(path)
	if path == "" {
		return FileConfig{}, fmt.Errorf("config path is required")
	}

	cfg := FileConfig{}
	if data, err := os.ReadFile(path); err == nil {
		if err := json.Unmarshal(data, &cfg); err != nil {
			return FileConfig{}, fmt.Errorf("invalid config JSON %s: %w", path, err)
		}
	} else if !os.IsNotExist(err) {
		return FileConfig{}, fmt.Errorf("read config %s: %w", path, err)
	}

	cfg.Preferences.FavoriteModels = normalizeFavoriteModels(models)
	if err := writeConfigFile(path, cfg); err != nil {
		return FileConfig{}, err
	}
	return cfg, nil
}

// SetRecapsEnabled persists the post-turn recap preference, mirroring
// SetFavoriteModels (read-modify-atomic-write).
func SetRecapsEnabled(path string, enabled bool) (FileConfig, error) {
	path = strings.TrimSpace(path)
	if path == "" {
		return FileConfig{}, fmt.Errorf("config path is required")
	}
	cfg := FileConfig{}
	if data, err := os.ReadFile(path); err == nil {
		if err := json.Unmarshal(data, &cfg); err != nil {
			return FileConfig{}, fmt.Errorf("invalid config JSON %s: %w", path, err)
		}
	} else if !os.IsNotExist(err) {
		return FileConfig{}, fmt.Errorf("read config %s: %w", path, err)
	}
	v := enabled
	cfg.Preferences.Recaps = &v
	if err := writeConfigFile(path, cfg); err != nil {
		return FileConfig{}, err
	}
	return cfg, nil
}

// SetTheme persists the TUI theme preference, mirroring SetFavoriteModels
// (read-modify-atomic-write). A blank theme clears the stored preference.
func SetTheme(path string, theme string) (FileConfig, error) {
	path = strings.TrimSpace(path)
	if path == "" {
		return FileConfig{}, fmt.Errorf("config path is required")
	}
	cfg := FileConfig{}
	if data, err := os.ReadFile(path); err == nil {
		if err := json.Unmarshal(data, &cfg); err != nil {
			return FileConfig{}, fmt.Errorf("invalid config JSON %s: %w", path, err)
		}
	} else if !os.IsNotExist(err) {
		return FileConfig{}, fmt.Errorf("read config %s: %w", path, err)
	}
	cfg.Preferences.Theme = strings.TrimSpace(theme)
	if err := writeConfigFile(path, cfg); err != nil {
		return FileConfig{}, err
	}
	return cfg, nil
}

func normalizeFavoriteModels(models []string) []string {
	seen := map[string]bool{}
	favorites := make([]string, 0, len(models))
	for _, model := range models {
		model = strings.TrimSpace(model)
		if model == "" || seen[model] {
			continue
		}
		seen[model] = true
		favorites = append(favorites, model)
	}
	sort.Strings(favorites)
	return favorites
}

func writeConfigFile(path string, cfg FileConfig) error {
	dir := filepath.Dir(path)
	if dir != "." && dir != "" {
		if err := os.MkdirAll(dir, 0o700); err != nil {
			return fmt.Errorf("create config directory %s: %w", dir, err)
		}
	}
	data, err := json.MarshalIndent(cfg, "", "  ")
	if err != nil {
		return fmt.Errorf("encode config JSON: %w", err)
	}
	data = append(data, '\n')
	// Write-to-temp + rename: an in-place write interrupted mid-way (crash,
	// disk full) would leave the user's only config truncated or corrupt.
	tmp, err := os.CreateTemp(dir, ".zero-config-*.tmp")
	if err != nil {
		return fmt.Errorf("write config %s: %w", path, err)
	}
	tmpPath := tmp.Name()
	defer os.Remove(tmpPath)
	if err := tmp.Chmod(0o600); err != nil {
		_ = tmp.Close()
		return fmt.Errorf("secure config permissions %s: %w", path, err)
	}
	if _, err := tmp.Write(data); err != nil {
		_ = tmp.Close()
		return fmt.Errorf("write config %s: %w", path, err)
	}
	if err := tmp.Close(); err != nil {
		return fmt.Errorf("write config %s: %w", path, err)
	}
	if err := os.Rename(tmpPath, path); err != nil {
		return fmt.Errorf("write config %s: %w", path, err)
	}
	return nil
}