package config

import (
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

var defaultLocalAllowedDomains = []string{"127.0.0.1", "localhost", "::1"}

func homeDir() string {
	if home := os.Getenv("HOME"); home != "" {
		return home
	}
	h, _ := os.UserHomeDir()
	return h
}

func userConfigDir() string {
	home := homeDir()
	legacyPath := filepath.Join(home, ".pinchtab")

	configDir, err := os.UserConfigDir()
	if err != nil {
		return legacyPath
	}

	newPath := filepath.Join(configDir, "pinchtab")

	// Priority 1: Check for config FILE (handles case where both dirs exist
	// but only legacy has config.json — the issue #224 scenario)
	legacyConfig := filepath.Join(legacyPath, "config.json")
	newConfig := filepath.Join(newPath, "config.json")

	if fileExists(legacyConfig) && !fileExists(newConfig) {
		return legacyPath
	}

	// Priority 2: Check for DIRECTORY (handles init scenario where
	// legacy dir exists from npm install but no config yet)
	if dirExists(legacyPath) && !dirExists(newPath) {
		return legacyPath
	}

	return newPath
}

func fileExists(path string) bool {
	info, err := os.Stat(path)
	return err == nil && !info.IsDir()
}

// DefaultConfigPath returns the default config file location used when
// PINCHTAB_CONFIG is not explicitly set.
func DefaultConfigPath() string {
	return filepath.Join(userConfigDir(), "config.json")
}

func dirExists(path string) bool {
	info, err := os.Stat(path)
	if err != nil {
		return false
	}
	return info.IsDir()
}

func (c *RuntimeConfig) ListenAddr() string {
	return c.Bind + ":" + c.Port
}

func GenerateAuthToken() (string, error) {
	buf := make([]byte, 24)
	if _, err := rand.Read(buf); err != nil {
		return "", fmt.Errorf("generate auth token: %w", err)
	}
	return hex.EncodeToString(buf), nil
}

func MaskToken(t string) string {
	if t == "" {
		return "(none)"
	}
	if len(t) <= 8 {
		return "***"
	}
	return t[:4] + "..." + t[len(t)-4:]
}

// NeedsWizard returns true if the config has no version or an older version than current.
func NeedsWizard(cfg *FileConfig) bool {
	if cfg.ConfigVersion == "" {
		return true
	}
	return CompareVersions(cfg.ConfigVersion, CurrentConfigVersion) < 0
}

// IsFirstRun returns true if the config has never been through the wizard.
func IsFirstRun(cfg *FileConfig) bool {
	return cfg.ConfigVersion == ""
}

// CompareVersions compares two semver-like version strings.
// Returns -1 if a < b, 0 if a == b, 1 if a > b.
func CompareVersions(a, b string) int {
	aParts := splitVersion(a)
	bParts := splitVersion(b)
	for i := 0; i < 3; i++ {
		if aParts[i] < bParts[i] {
			return -1
		}
		if aParts[i] > bParts[i] {
			return 1
		}
	}
	return 0
}

func splitVersion(v string) [3]int {
	parts := [3]int{}
	segs := strings.SplitN(v, ".", 3)
	for i, s := range segs {
		if i >= 3 {
			break
		}
		n := 0
		for _, c := range s {
			if c >= '0' && c <= '9' {
				n = n*10 + int(c-'0')
			}
		}
		parts[i] = n
	}
	return parts
}