package main

import (
	"encoding/hex"
	"fmt"
	"os"

	"gopkg.in/yaml.v3"
)

// Config holds all relay configuration loaded from config.yaml.
type Config struct {
	Addr      string   `yaml:"addr"`
	DB        string   `yaml:"db"`
	RelayURL  string   `yaml:"relay_url"`
	Allowlist []string `yaml:"allowlist"` // hex-encoded pubkeys
}

// DefaultConfig returns sensible defaults.
func DefaultConfig() Config {
	return Config{
		Addr:     ":8080",
		DB:       "axon.db",
		RelayURL: "ws://localhost:8080",
	}
}

// AllowlistBytes decodes the hex pubkeys in c.Allowlist and returns them as
// raw byte slices. Returns an error if any entry is not valid 64-char hex.
func (c *Config) AllowlistBytes() ([][]byte, error) {
	out := make([][]byte, 0, len(c.Allowlist))
	for _, h := range c.Allowlist {
		b, err := hex.DecodeString(h)
		if err != nil {
			return nil, fmt.Errorf("config: allowlist entry %q is not valid hex: %w", h, err)
		}
		if len(b) != 32 {
			return nil, fmt.Errorf("config: allowlist entry %q decoded to %d bytes, want 32", h, len(b))
		}
		out = append(out, b)
	}
	return out, nil
}

// LoadConfig reads and parses a YAML config file. Missing fields fall back to
// DefaultConfig values.
func LoadConfig(path string) (Config, error) {
	cfg := DefaultConfig()

	f, err := os.Open(path)
	if err != nil {
		if os.IsNotExist(err) {
			// No config file — use defaults.
			return cfg, nil
		}
		return cfg, fmt.Errorf("config: open %q: %w", path, err)
	}
	defer f.Close()

	dec := yaml.NewDecoder(f)
	dec.KnownFields(true)
	if err := dec.Decode(&cfg); err != nil {
		return cfg, fmt.Errorf("config: decode %q: %w", path, err)
	}
	return cfg, nil
}