// Package config parses the clip-sync TOML configuration file and applies
// environment variable overrides.
//
// Config file location: ~/.config/clip-sync/peers.toml
// Environment overrides:
//   CLIP_SYNC_PORT       — override daemon.port
//   CLIP_SYNC_POLL_MS    — override daemon.poll_interval_ms
package config

import (
	"fmt"
	"os"
	"path/filepath"
	"strconv"
	"time"

	"github.com/BurntSushi/toml"
)

// Config represents the full clip-sync configuration.
type Config struct {
	Daemon DaemonConfig `toml:"daemon"`
	Peers  []PeerConfig `toml:"peers"`
}

// DaemonConfig holds daemon-level settings.
type DaemonConfig struct {
	Port           int `toml:"port"`
	PollIntervalMs int `toml:"poll_interval_ms"`
}

// PeerConfig represents one remote clip-sync peer.
type PeerConfig struct {
	Name string `toml:"name"`
	Addr string `toml:"addr"`
}

// Default values.
const (
	DefaultPort           = 9137
	DefaultPollIntervalMs = 500
	ConfigDir             = ".config/clip-sync"
	ConfigFile            = "peers.toml"
)

// Load reads the config file from ~/.config/clip-sync/peers.toml and applies
// environment variable overrides.
func Load() (*Config, error) {
	home, err := os.UserHomeDir()
	if err != nil {
		return nil, fmt.Errorf("config: cannot find home directory: %w", err)
	}

	cfgPath := filepath.Join(home, ConfigDir, ConfigFile)

	cfg := &Config{
		Daemon: DaemonConfig{
			Port:           DefaultPort,
			PollIntervalMs: DefaultPollIntervalMs,
		},
	}

	if _, err := toml.DecodeFile(cfgPath, cfg); err != nil {
		if !os.IsNotExist(err) {
			return nil, fmt.Errorf("config: cannot parse %s: %w", cfgPath, err)
		}
		// File doesn't exist — use defaults (no peers configured).
	}

	// Environment variable overrides.
	if v := os.Getenv("CLIP_SYNC_PORT"); v != "" {
		port, err := strconv.Atoi(v)
		if err != nil {
			return nil, fmt.Errorf("config: invalid CLIP_SYNC_PORT: %w", err)
		}
		cfg.Daemon.Port = port
	}

	if v := os.Getenv("CLIP_SYNC_POLL_MS"); v != "" {
		ms, err := strconv.Atoi(v)
		if err != nil {
			return nil, fmt.Errorf("config: invalid CLIP_SYNC_POLL_MS: %w", err)
		}
		cfg.Daemon.PollIntervalMs = ms
	}

	return cfg, nil
}

// PollInterval returns the poll interval as a time.Duration.
func (c *Config) PollInterval() time.Duration {
	return time.Duration(c.Daemon.PollIntervalMs) * time.Millisecond
}

// ListenAddr returns the HTTP listen address for this daemon.
func (c *Config) ListenAddr() string {
	return fmt.Sprintf(":%d", c.Daemon.Port)
}