package iam

import (
	"fmt"
	"strings"

	"git.frostfs.info/TrueCloudLab/policy-engine/pkg/chain"
	"git.frostfs.info/TrueCloudLab/policy-engine/schema/s3"
)

const condKeyAWSMFAPresent = "aws:MultiFactorAuthPresent"

var actionToS3OpMap = map[string][]string{
	s3ActionAbortMultipartUpload:  {s3ActionAbortMultipartUpload},
	s3ActionCreateBucket:          {s3ActionCreateBucket},
	s3ActionDeleteBucket:          {s3ActionDeleteBucket},
	s3ActionDeleteBucketPolicy:    {s3ActionDeleteBucketPolicy},
	s3ActionDeleteObjectTagging:   {s3ActionDeleteObjectTagging},
	s3ActionGetBucketLocation:     {s3ActionGetBucketLocation},
	s3ActionGetBucketNotification: {s3ActionGetBucketNotification},
	s3ActionGetBucketPolicy:       {s3ActionGetBucketPolicy},
	s3ActionGetBucketPolicyStatus: {s3ActionGetBucketPolicyStatus},
	s3ActionGetBucketTagging:      {s3ActionGetBucketTagging},
	s3ActionGetBucketVersioning:   {s3ActionGetBucketVersioning},
	s3ActionGetObjectAttributes:   {s3ActionGetObjectAttributes},
	s3ActionGetObjectLegalHold:    {s3ActionGetObjectLegalHold},
	s3ActionGetObjectRetention:    {s3ActionGetObjectRetention},
	s3ActionGetObjectTagging:      {s3ActionGetObjectTagging},
	s3ActionPutBucketNotification: {s3ActionPutBucketNotification},
	s3ActionPutBucketPolicy:       {s3ActionPutBucketPolicy},
	s3ActionPutBucketVersioning:   {s3ActionPutBucketVersioning},
	s3ActionPutObjectLegalHold:    {s3ActionPutObjectLegalHold},
	s3ActionPutObjectRetention:    {s3ActionPutObjectRetention},
	s3ActionPutObjectTagging:      {s3ActionPutObjectTagging},

	s3ActionListAllMyBuckets:                 {"s3:ListBuckets"},
	s3ActionListBucket:                       {"s3:HeadBucket", "s3:GetBucketLocation", "s3:ListObjectsV1", "s3:ListObjectsV2"},
	s3ActionListBucketVersions:               {"s3:ListBucketObjectVersions"},
	s3ActionListBucketMultipartUploads:       {"s3:ListMultipartUploads"},
	s3ActionGetBucketObjectLockConfiguration: {"s3:GetBucketObjectLockConfig"},
	s3ActionGetLifecycleConfiguration:        {"s3:GetBucketLifecycle"},
	s3ActionGetBucketACL:                     {"s3:GetBucketACL"},
	s3ActionGetBucketCORS:                    {"s3:GetBucketCors"},
	s3ActionPutBucketTagging:                 {"s3:PutBucketTagging", "s3:DeleteBucketTagging"},
	s3ActionPutBucketObjectLockConfiguration: {"s3:PutBucketObjectLockConfig"},
	s3ActionPutLifecycleConfiguration:        {"s3:PutBucketLifecycle", "s3:DeleteBucketLifecycle"},
	s3ActionPutBucketACL:                     {"s3:PutBucketACL"},
	s3ActionPutBucketCORS:                    {"s3:PutBucketCors", "s3:DeleteBucketCors"},

	s3ActionListMultipartUploadParts:   {"s3:ListParts"},
	s3ActionGetObjectACL:               {"s3:GetObjectACL"},
	s3ActionGetObject:                  {"s3:GetObject", "s3:HeadObject"},
	s3ActionGetObjectVersion:           {"s3:GetObject", "s3:HeadObject"},
	s3ActionGetObjectVersionACL:        {"s3:GetObjectACL"},
	s3ActionGetObjectVersionAttributes: {"s3:GetObjectAttributes"},
	s3ActionGetObjectVersionTagging:    {"s3:GetObjectTagging"},
	s3ActionPutObjectACL:               {"s3:PutObjectACL"},
	s3ActionPutObjectVersionACL:        {"s3:PutObjectACL"},
	s3ActionPutObjectVersionTagging:    {"s3:PutObjectTagging"},
	s3ActionPutObject: {
		"s3:PutObject", "s3:PostObject", "s3:CopyObject",
		"s3:UploadPart", "s3:UploadPartCopy", "s3:CreateMultipartUpload", "s3:CompleteMultipartUpload",
	},
	s3ActionDeleteObjectVersionTagging: {"s3:DeleteObjectTagging"},
	s3ActionDeleteObject:               {"s3:DeleteObject", "s3:DeleteMultipleObjects"},
	s3ActionDeleteObjectVersion:        {"s3:DeleteObject", "s3:DeleteMultipleObjects"},
}

type S3Resolver interface {
	GetUserAddress(account, user string) (string, error)
}

func ConvertToS3Chain(p Policy, resolver S3Resolver) (*chain.Chain, error) {
	if err := p.Validate(ResourceBasedPolicyType); err != nil {
		return nil, err
	}

	var engineChain chain.Chain

	for _, statement := range p.Statement {
		status := formStatus(statement)

		actions, actionInverted := statement.action()
		s3Actions, err := formS3ActionNames(actions)
		if err != nil {
			return nil, err
		}
		ruleAction := chain.Actions{Inverted: actionInverted, Names: s3Actions}
		if len(ruleAction.Names) == 0 {
			continue
		}

		resources, resourceInverted := statement.resource()
		if err := validateS3ResourceNames(resources); err != nil {
			return nil, err
		}
		ruleResource := chain.Resources{Inverted: resourceInverted, Names: resources}

		groupedConditions, err := convertToS3ChainCondition(statement.Conditions, resolver)
		if err != nil {
			return nil, err
		}
		splitConditions := splitGroupedConditions(groupedConditions)

		principals, principalCondFn, err := getS3PrincipalsAndConditionFunc(statement, resolver)
		if err != nil {
			return nil, err
		}

		for _, principal := range principals {
			for _, conditions := range splitConditions {
				var principalCondition []chain.Condition
				if principal != Wildcard {
					principalCondition = []chain.Condition{principalCondFn(principal)}
				}

				r := chain.Rule{
					Status:    status,
					Actions:   ruleAction,
					Resources: ruleResource,
					Condition: append(principalCondition, conditions...),
				}
				engineChain.Rules = append(engineChain.Rules, r)
			}
		}
	}

	if len(engineChain.Rules) == 0 {
		return nil, ErrActionsNotApplicable
	}

	return &engineChain, nil
}

func getS3PrincipalsAndConditionFunc(statement Statement, resolver S3Resolver) ([]string, formPrincipalConditionFunc, error) {
	var principals []string
	var op chain.ConditionType
	statementPrincipal, inverted := statement.principal()
	if _, ok := statementPrincipal[Wildcard]; ok { // this can be true only if 'inverted' false
		principals = []string{Wildcard}
		op = chain.CondStringLike
	} else {
		for principalType, principal := range statementPrincipal {
			if principalType != AWSPrincipalType {
				return nil, nil, fmt.Errorf("unsupported principal type '%s'", principalType)
			}
			parsedPrincipal, err := formS3Principal(principal, resolver)
			if err != nil {
				return nil, nil, fmt.Errorf("parse principal: %w", err)
			}
			principals = append(principals, parsedPrincipal...)
		}

		op = chain.CondStringEquals
		if inverted {
			op = chain.CondStringNotEquals
		}
	}

	return principals, func(principal string) chain.Condition {
		return chain.Condition{
			Op:    op,
			Kind:  chain.KindRequest,
			Key:   s3.PropertyKeyOwner,
			Value: principal,
		}
	}, nil
}

func convertToS3ChainCondition(c Conditions, resolver S3Resolver) ([]GroupedConditions, error) {
	return convertToChainConditions(c, func(gr GroupedConditions) (GroupedConditions, error) {
		for i := range gr.Conditions {
			switch {
			case gr.Conditions[i].Key == condKeyAWSPrincipalARN:
				gr.Conditions[i].Key = s3.PropertyKeyOwner
				val, err := formPrincipalOwner(gr.Conditions[i].Value, resolver)
				if err != nil {
					return GroupedConditions{}, err
				}
				gr.Conditions[i].Value = val

			case gr.Conditions[i].Key == condKeyAWSMFAPresent:
				gr.Conditions[i].Key = s3.PropertyKeyAccessBoxAttrMFA
			case strings.HasPrefix(gr.Conditions[i].Key, condKeyAWSResourceTagPrefix):
				gr.Conditions[i].Kind = chain.KindResource
			}
		}

		return gr, nil
	})
}

func formS3Principal(principal []string, resolver S3Resolver) ([]string, error) {
	res := make([]string, len(principal))

	var err error
	for i := range principal {
		if res[i], err = formPrincipalOwner(principal[i], resolver); err != nil {
			return nil, err
		}
	}

	return res, nil
}

func formPrincipalOwner(principal string, resolver S3Resolver) (string, error) {
	account, user, err := parsePrincipalAsIAMUser(principal)
	if err != nil {
		return "", err
	}

	address, err := resolver.GetUserAddress(account, user)
	if err != nil {
		return "", fmt.Errorf("get user address: %w", err)
	}

	return address, nil
}

func validateS3ResourceNames(names []string) error {
	for i := range names {
		if err := validateResource(names[i]); err != nil {
			return err
		}
	}

	return nil
}

func formS3ActionNames(names []string) ([]string, error) {
	uniqueActions := make(map[string]struct{}, len(names))

	for _, action := range names {
		if action == Wildcard {
			return []string{Wildcard}, nil
		}

		isIAM, err := validateAction(action)
		if err != nil {
			return nil, err
		}

		if isIAM {
			uniqueActions[action] = struct{}{}
			continue
		}

		if action[len(s3ActionPrefix):] == Wildcard {
			uniqueActions[action] = struct{}{}
			continue
		}

		s3Actions := actionToS3OpMap[action]
		if len(s3Actions) == 0 {
			return nil, ErrActionsNotApplicable
		}

		for _, s3Action := range s3Actions {
			uniqueActions[s3Action] = struct{}{}
		}
	}

	res := make([]string, 0, len(uniqueActions))
	for key := range uniqueActions {
		res = append(res, key)
	}

	return res, nil
}