package validator

import (
	"fmt"
	"net"
	"regexp"
	"strings"

	"github.com/authelia/authelia/internal/configuration/schema"
	"github.com/authelia/authelia/internal/utils"
)

// IsPolicyValid check if policy is valid.
func IsPolicyValid(policy string) bool {
	return policy == denyPolicy || policy == "one_factor" || policy == "two_factor" || policy == "bypass"
}

// IsResourceValid check if a resource is valid.
func IsResourceValid(resource string) error {
	_, err := regexp.Compile(resource)
	return err
}

// IsSubjectValid check if a subject is valid.
func IsSubjectValid(subject string) bool {
	return subject == "" || strings.HasPrefix(subject, "user:") || strings.HasPrefix(subject, "group:")
}

// IsNetworkGroupValid check if a network group is valid.
func IsNetworkGroupValid(configuration schema.AccessControlConfiguration, network string) bool {
	for _, networks := range configuration.Networks {
		if !utils.IsStringInSlice(network, networks.Name) {
			continue
		} else {
			return true
		}
	}

	return false
}

// IsNetworkValid check if a network is valid.
func IsNetworkValid(network string) bool {
	if net.ParseIP(network) == nil {
		_, _, err := net.ParseCIDR(network)
		return err == nil
	}

	return true
}

// ValidateAccessControl validates access control configuration.
func ValidateAccessControl(configuration schema.AccessControlConfiguration, validator *schema.StructValidator) {
	if !IsPolicyValid(configuration.DefaultPolicy) {
		validator.Push(fmt.Errorf("'default_policy' must either be 'deny', 'two_factor', 'one_factor' or 'bypass'"))
	}

	if configuration.Networks != nil {
		for _, n := range configuration.Networks {
			for _, networks := range n.Networks {
				if !IsNetworkValid(networks) {
					validator.Push(fmt.Errorf("Network %s from network group: %s must be a valid IP or CIDR", n.Networks, n.Name))
				}
			}
		}
	}
}

// ValidateRules validates an ACL Rule configuration.
func ValidateRules(configuration schema.AccessControlConfiguration, validator *schema.StructValidator) {
	for _, r := range configuration.Rules {
		if len(r.Domains) == 0 {
			validator.Push(fmt.Errorf("No access control rules have been defined"))
		}

		if !IsPolicyValid(r.Policy) {
			validator.Push(fmt.Errorf("Policy [%s] for domain: %s is invalid, a policy must either be 'deny', 'two_factor', 'one_factor' or 'bypass'", r.Policy, r.Domains))
		}

		for _, network := range r.Networks {
			if !IsNetworkValid(network) {
				if !IsNetworkGroupValid(configuration, network) {
					validator.Push(fmt.Errorf("Network %s for domain: %s is not a valid network or network group", r.Networks, r.Domains))
				}
			}
		}

		for _, resource := range r.Resources {
			if err := IsResourceValid(resource); err != nil {
				validator.Push(fmt.Errorf("Resource %s for domain: %s is invalid, %s", r.Resources, r.Domains, err))
			}
		}

		for _, subjectRule := range r.Subjects {
			for _, subject := range subjectRule {
				if !IsSubjectValid(subject) {
					validator.Push(fmt.Errorf("Subject %s for domain: %s must start with 'user:' or 'group:'", subjectRule, r.Domains))
				}
			}
		}
	}
}