package client

import (
	"encoding/json"
	"errors"
	"os"
	"path/filepath"
)

// Config is what a client remembers between runs. The session token lives
// here; the KDBX master passwords never do, because the client never opens a
// database, it only moves bytes.
type Config struct {
	ServerURL string `json:"server_url"`
	Token     string `json:"token"`
	Username  string `json:"username"`
	MirrorDir string `json:"mirror_dir"`
	// PollSeconds is how often the mirror is rescanned for local saves.
	PollSeconds int `json:"poll_seconds"`
}

// ErrNoConfig means the client has not been logged in yet.
var ErrNoConfig = errors.New("not logged in: run `keeporg login` first")

// DefaultConfigPath is the per-user configuration path on this platform.
func DefaultConfigPath() string {
	dir, err := os.UserConfigDir()
	if err != nil {
		return filepath.Join(".", ".keeporg", "config.json")
	}
	return filepath.Join(dir, "keeporg", "config.json")
}

// DefaultMirrorDir is where databases are mirrored unless told otherwise.
func DefaultMirrorDir() string {
	home, err := os.UserHomeDir()
	if err != nil {
		return "keeporg"
	}
	return filepath.Join(home, "KeepOrg")
}

// LoadConfig reads a configuration file.
func LoadConfig(path string) (*Config, error) {
	b, err := os.ReadFile(path)
	if os.IsNotExist(err) {
		return nil, ErrNoConfig
	}
	if err != nil {
		return nil, err
	}
	var c Config
	if err := json.Unmarshal(b, &c); err != nil {
		return nil, err
	}
	if c.MirrorDir == "" {
		c.MirrorDir = DefaultMirrorDir()
	}
	if c.PollSeconds <= 0 {
		c.PollSeconds = 2
	}
	return &c, nil
}

// Save writes the configuration with owner-only permissions, since it holds
// a bearer token.
func (c *Config) Save(path string) error {
	if err := os.MkdirAll(filepath.Dir(path), 0o700); err != nil {
		return err
	}
	b, err := json.MarshalIndent(c, "", "  ")
	if err != nil {
		return err
	}
	tmp := path + ".tmp"
	if err := os.WriteFile(tmp, append(b, '\n'), 0o600); err != nil {
		return err
	}
	return os.Rename(tmp, path)
}