package profile

import (
	"errors"
	"fmt"
	"net"
	"net/url"
	"regexp"
	"strconv"
	"strings"
)

type Mode string

const (
	SingleMode   Mode = "single"
	AdvancedMode Mode = "advanced"
)

type Profile struct {
	Name      string   `json:"name"`
	Mode      Mode     `json:"mode"`
	SingleURL string   `json:"singleUrl,omitempty"`
	HTTPURL   string   `json:"httpUrl,omitempty"`
	HTTPSURL  string   `json:"httpsUrl,omitempty"`
	AllURL    string   `json:"allUrl,omitempty"`
	Bypass    []string `json:"bypass,omitempty"`
}

type State struct {
	Profiles      []Profile `json:"profiles"`
	ActiveProfile string    `json:"activeProfile,omitempty"`
}

type Store interface {
	Load() (State, error)
	Mutate(func(State) (State, error)) (State, error)
}

func ValidateAndNormalize(input Profile) (Profile, error) {
	p := input
	p.Name = strings.TrimSpace(p.Name)
	if p.Name == "" {
		return Profile{}, errors.New("Profile name is required")
	}
	if p.Mode == "" {
		p.Mode = SingleMode
	}
	switch p.Mode {
	case SingleMode:
		value, err := validateURL("Single proxy URL", p.SingleURL)
		if err != nil {
			return Profile{}, err
		}
		p.SingleURL = value
		p.HTTPURL, p.HTTPSURL, p.AllURL = value, value, value
	case AdvancedMode:
		if p.HTTPURL == "" && p.HTTPSURL == "" && p.AllURL == "" && strings.TrimSpace(p.SingleURL) != "" {
			value, err := validateURL("Single proxy URL", p.SingleURL)
			if err != nil {
				return Profile{}, err
			}
			p.SingleURL = value
			p.HTTPURL, p.HTTPSURL, p.AllURL = value, value, value
		}
		var err error
		if p.HTTPURL, err = validateOptionalURL("HTTP proxy URL", p.HTTPURL); err != nil {
			return Profile{}, err
		}
		if p.HTTPSURL, err = validateOptionalURL("HTTPS proxy URL", p.HTTPSURL); err != nil {
			return Profile{}, err
		}
		if p.AllURL, err = validateOptionalURL("ALL/SOCKS proxy URL", p.AllURL); err != nil {
			return Profile{}, err
		}
		if p.HTTPURL == "" && p.HTTPSURL == "" && p.AllURL == "" {
			return Profile{}, errors.New("at least one advanced proxy URL is required")
		}
	default:
		return Profile{}, errors.New("proxy mode must be single or advanced")
	}

	bypass, err := normalizeBypass(p.Bypass)
	if err != nil {
		return Profile{}, err
	}
	p.Bypass = bypass
	return p, nil
}

func validateOptionalURL(field, value string) (string, error) {
	if strings.TrimSpace(value) == "" {
		return "", nil
	}
	return validateURL(field, value)
}

func validateURL(field, value string) (string, error) {
	value = strings.TrimSpace(value)
	if value == "" {
		return "", fmt.Errorf("%s is required", field)
	}
	u, err := url.Parse(value)
	if err != nil {
		return "", fmt.Errorf("%s is malformed", field)
	}
	switch strings.ToLower(u.Scheme) {
	case "http", "https", "socks5", "socks5h":
	default:
		return "", fmt.Errorf("%s must use http, https, socks5, or socks5h", field)
	}
	if u.Hostname() == "" {
		return "", fmt.Errorf("%s must include a host", field)
	}
	if u.Path != "" || u.RawQuery != "" || u.Fragment != "" {
		return "", fmt.Errorf("%s must not include a path, query, or fragment", field)
	}
	port := u.Port()
	if port == "" {
		return "", fmt.Errorf("%s must include a port", field)
	}
	n, err := strconv.Atoi(port)
	if err != nil || n < 1 || n > 65535 {
		return "", fmt.Errorf("%s port must be between 1 and 65535", field)
	}
	if net.ParseIP(u.Hostname()) == nil && (looksLikeIPv4(u.Hostname()) || !validHostname(u.Hostname())) {
		return "", fmt.Errorf("%s contains an invalid host", field)
	}
	u.Scheme = strings.ToLower(u.Scheme)
	return u.String(), nil
}

func normalizeBypass(values []string) ([]string, error) {
	result := make([]string, 0, len(values))
	seen := make(map[string]bool)
	for _, raw := range values {
		for _, item := range strings.FieldsFunc(raw, func(r rune) bool { return r == ',' || r == '\n' }) {
			value, err := normalizeBypassEntry(item)
			if err != nil {
				return nil, err
			}
			if !seen[value] {
				seen[value] = true
				result = append(result, value)
			}
		}
	}
	return result, nil
}

func normalizeBypassEntry(raw string) (string, error) {
	value := strings.TrimSpace(raw)
	if value == "" {
		return "", errors.New("Bypass entries cannot be empty")
	}
	if _, network, err := net.ParseCIDR(value); err == nil {
		return network.String(), nil
	}
	if ip := net.ParseIP(value); ip != nil {
		return ip.String(), nil
	}
	suffix := strings.HasPrefix(value, ".")
	host := strings.ToLower(strings.TrimSuffix(strings.TrimPrefix(value, "."), "."))
	if looksLikeIPv4(host) || !validHostname(host) {
		return "", errors.New("Bypass entry must be a hostname, domain suffix, IP address, or CIDR range")
	}
	if suffix {
		return "." + host, nil
	}
	return host, nil
}

var credentialPattern = regexp.MustCompile(`(?i)(https?|socks5h?)://([^/@\s:]+):([^@\s]*)@`)

// RedactText removes URL passwords from diagnostic text without requiring the
// surrounding text to be a valid URL.
func RedactText(value string) string {
	return credentialPattern.ReplaceAllString(value, `${1}://${2}:REDACTED@`)
}

func ObscureURL(value string) string {
	u, err := url.Parse(value)
	if err != nil || u.User == nil {
		return RedactText(value)
	}
	if _, present := u.User.Password(); !present {
		return value
	}
	u.User = url.UserPassword(u.User.Username(), "REDACTED")
	return u.String()
}

func looksLikeIPv4(host string) bool {
	parts := strings.Split(host, ".")
	if len(parts) != 4 {
		return false
	}
	for _, part := range parts {
		if part == "" {
			return false
		}
		for _, r := range part {
			if r < '0' || r > '9' {
				return false
			}
		}
	}
	return true
}

func validHostname(host string) bool {
	if len(host) == 0 || len(host) > 253 || strings.HasPrefix(host, ".") || strings.HasSuffix(host, ".") {
		return false
	}
	for _, label := range strings.Split(host, ".") {
		if len(label) == 0 || len(label) > 63 || label[0] == '-' || label[len(label)-1] == '-' {
			return false
		}
		for _, r := range label {
			if !((r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') || r == '-') {
				return false
			}
		}
	}
	return true
}