package cli

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

// Credentials stores the logged-in user's session info.
type Credentials struct {
	ServerURL string `json:"server_url"`
	Token     string `json:"token"`
	UserID    string `json:"user_id"`
	Email     string `json:"email"`
	Name      string `json:"name"`
}

// CredentialsPath returns ~/.pad/credentials.json.
func CredentialsPath() (string, error) {
	homeDir, err := os.UserHomeDir()
	if err != nil {
		return "", fmt.Errorf("get home directory: %w", err)
	}
	return filepath.Join(homeDir, ".pad", "credentials.json"), nil
}

// credentialsPath is retained for internal call sites.
func credentialsPath() (string, error) {
	return CredentialsPath()
}

// LoadCredentials reads the credentials file. Returns nil if the file
// doesn't exist (not an error — just means not logged in).
func LoadCredentials() (*Credentials, error) {
	path, err := credentialsPath()
	if err != nil {
		return nil, err
	}

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

	var creds Credentials
	if err := json.Unmarshal(data, &creds); err != nil {
		return nil, fmt.Errorf("parse credentials: %w", err)
	}
	return &creds, nil
}

// SaveCredentials writes credentials to disk with 0600 permissions.
func SaveCredentials(creds *Credentials) error {
	path, err := credentialsPath()
	if err != nil {
		return err
	}

	// Ensure directory exists
	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
		return fmt.Errorf("create credentials directory: %w", err)
	}

	data, err := json.MarshalIndent(creds, "", "  ")
	if err != nil {
		return fmt.Errorf("marshal credentials: %w", err)
	}

	if err := os.WriteFile(path, data, 0600); err != nil {
		return fmt.Errorf("write credentials: %w", err)
	}
	return nil
}

// DeleteCredentials removes the credentials file.
func DeleteCredentials() error {
	path, err := credentialsPath()
	if err != nil {
		return err
	}

	if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("delete credentials: %w", err)
	}
	return nil
}