package config

import (
	"flag"
	"log"
	"os"
	"path"
	"strings"
)

type Config struct {
	Bind             string
	WifiInterface    string
	HotspotInterface string
	WifiBackend      string
	StationBackend   string // "arp", "dhcp", or "hostapd"
	DHCPLeasesPath   string
	ARPTablePath     string
	SyslogEnabled    bool
	SyslogPath       string
	SyslogFilter     []string
	SyslogSource     string
}

// ConsolidateConfig fills an Options struct by reading configuration from
// config files, environment, then command line.
//
// Should be called only one time.
func ConsolidateConfig() (opts *Config, err error) {
	// Define defaults options
	opts = &Config{
		Bind:             ":8080",
		WifiInterface:    "wlan0",
		HotspotInterface: "wlan1",
		DHCPLeasesPath:   "/var/lib/dhcp/dhcpd.leases",
		ARPTablePath:     "/proc/net/arp",
		SyslogEnabled:    false,
		SyslogPath:       "/var/log/messages",
		SyslogFilter:     []string{"daemon.info wpa_supplicant:", "daemon.info iwd:", "daemon.info hostapd:"},
		SyslogSource:     "iwd",
	}

	declareFlags(opts)

	// Establish a list of possible configuration file locations
	configLocations := []string{
		"repeater.conf",
	}

	if home, err := os.UserConfigDir(); err == nil {
		configLocations = append(configLocations, path.Join(home, "repeater", "repeater.conf"))
	}

	configLocations = append(configLocations, path.Join("etc", "repeater.conf"))

	// If config file exists, read configuration from it
	for _, filename := range configLocations {
		if _, e := os.Stat(filename); !os.IsNotExist(e) {
			log.Printf("Loading configuration from %s\n", filename)
			err = parseFile(opts, filename)
			if err != nil {
				return
			}
			break
		}
	}

	// Then, overwrite that by what is present in the environment
	err = parseEnvironmentVariables(opts)
	if err != nil {
		return
	}

	// Finaly, command line takes precedence
	err = parseCLI(opts)
	if err != nil {
		return
	}

	// Validate configuration
	if opts.WifiBackend != "iwd" && opts.WifiBackend != "wpasupplicant" {
		log.Fatalf("wifi-backend must be set to 'iwd' or 'wpasupplicant' (got: '%s')", opts.WifiBackend)
	}

	if opts.StationBackend != "arp" && opts.StationBackend != "dhcp" && opts.StationBackend != "hostapd" {
		log.Fatalf("station-backend must be set to 'arp', 'dhcp', or 'hostapd' (got: '%s')", opts.StationBackend)
	}

	return
}

// parseLine treats a config line and place the read value in the variable
// declared to the corresponding flag.
func parseLine(o *Config, line string) (err error) {
	fields := strings.SplitN(line, "=", 2)
	orig_key := strings.TrimSpace(fields[0])
	value := strings.TrimSpace(fields[1])

	key := strings.TrimPrefix(orig_key, "REPEATER_")
	key = strings.Replace(key, "_", "-", -1)
	key = strings.ToLower(key)

	err = flag.Set(key, value)

	return
}