package grpcserver

import (
	"context"
	"errors"
	"strings"

	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"

	pb "git.wntrmute.dev/kyle/metacrypt/gen/metacrypt/v2"
	"git.wntrmute.dev/kyle/metacrypt/internal/engine"
	"git.wntrmute.dev/kyle/metacrypt/internal/engine/transit"
	"git.wntrmute.dev/kyle/metacrypt/internal/policy"
)

type transitServer struct {
	pb.UnimplementedTransitServiceServer
	s *GRPCServer
}

func (ts *transitServer) transitHandleRequest(ctx context.Context, mount, operation string, req *engine.Request) (*engine.Response, error) {
	resp, err := ts.s.engines.HandleRequest(ctx, mount, req)
	if err != nil {
		st := codes.Internal
		switch {
		case errors.Is(err, engine.ErrMountNotFound):
			st = codes.NotFound
		case errors.Is(err, transit.ErrKeyNotFound):
			st = codes.NotFound
		case errors.Is(err, transit.ErrKeyExists):
			st = codes.AlreadyExists
		case errors.Is(err, transit.ErrUnauthorized):
			st = codes.Unauthenticated
		case errors.Is(err, transit.ErrForbidden):
			st = codes.PermissionDenied
		case errors.Is(err, transit.ErrDeletionDenied):
			st = codes.FailedPrecondition
		case errors.Is(err, transit.ErrUnsupportedOp):
			st = codes.InvalidArgument
		case errors.Is(err, transit.ErrDecryptVersion):
			st = codes.FailedPrecondition
		case errors.Is(err, transit.ErrInvalidFormat):
			st = codes.InvalidArgument
		case errors.Is(err, transit.ErrBatchTooLarge):
			st = codes.InvalidArgument
		case errors.Is(err, transit.ErrInvalidMinVer):
			st = codes.InvalidArgument
		case strings.Contains(err.Error(), "not found"):
			st = codes.NotFound
		case strings.Contains(err.Error(), "forbidden"):
			st = codes.PermissionDenied
		}
		ts.s.logger.Error("grpc: transit "+operation, "mount", mount, "error", err)
		return nil, status.Error(st, err.Error())
	}
	return resp, nil
}

func (ts *transitServer) callerInfo(ctx context.Context) *engine.CallerInfo {
	ti := tokenInfoFromContext(ctx)
	if ti == nil {
		return nil
	}
	return &engine.CallerInfo{
		Username: ti.Username,
		Roles:    ti.Roles,
		IsAdmin:  ti.IsAdmin,
	}
}

func (ts *transitServer) policyChecker(ctx context.Context) engine.PolicyChecker {
	caller := ts.callerInfo(ctx)
	if caller == nil {
		return nil
	}
	return func(resource, action string) (string, bool) {
		pReq := &policy.Request{
			Username: caller.Username,
			Roles:    caller.Roles,
			Resource: resource,
			Action:   action,
		}
		effect, matched, err := ts.s.policy.Match(ctx, pReq)
		if err != nil {
			return string(policy.EffectDeny), false
		}
		return string(effect), matched
	}
}

func (ts *transitServer) CreateKey(ctx context.Context, req *pb.CreateTransitKeyRequest) (*pb.CreateTransitKeyResponse, error) {
	if req.Mount == "" || req.Name == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and name are required")
	}
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "create-key", &engine.Request{
		Operation:  "create-key",
		CallerInfo: ts.callerInfo(ctx),
		Data: map[string]interface{}{
			"name": req.Name,
			"type": req.Type,
		},
	})
	if err != nil {
		return nil, err
	}
	name, _ := resp.Data["name"].(string)
	keyType, _ := resp.Data["type"].(string)
	version, _ := resp.Data["version"].(int)
	ts.s.logger.Info("audit: transit key created", "mount", req.Mount, "key", name, "type", keyType, "username", callerUsername(ctx))
	return &pb.CreateTransitKeyResponse{Name: name, Type: keyType, Version: int32(version)}, nil
}

func (ts *transitServer) DeleteKey(ctx context.Context, req *pb.DeleteTransitKeyRequest) (*pb.DeleteTransitKeyResponse, error) {
	if req.Mount == "" || req.Name == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and name are required")
	}
	_, err := ts.transitHandleRequest(ctx, req.Mount, "delete-key", &engine.Request{
		Operation:  "delete-key",
		CallerInfo: ts.callerInfo(ctx),
		Data:       map[string]interface{}{"name": req.Name},
	})
	if err != nil {
		return nil, err
	}
	ts.s.logger.Info("audit: transit key deleted", "mount", req.Mount, "key", req.Name, "username", callerUsername(ctx))
	return &pb.DeleteTransitKeyResponse{}, nil
}

func (ts *transitServer) GetKey(ctx context.Context, req *pb.GetTransitKeyRequest) (*pb.GetTransitKeyResponse, error) {
	if req.Mount == "" || req.Name == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and name are required")
	}
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "get-key", &engine.Request{
		Operation:  "get-key",
		CallerInfo: ts.callerInfo(ctx),
		Data:       map[string]interface{}{"name": req.Name},
	})
	if err != nil {
		return nil, err
	}
	name, _ := resp.Data["name"].(string)
	keyType, _ := resp.Data["type"].(string)
	currentVersion, _ := resp.Data["current_version"].(int)
	minDecryptionVersion, _ := resp.Data["min_decryption_version"].(int)
	allowDeletion, _ := resp.Data["allow_deletion"].(bool)
	rawVersions, _ := resp.Data["versions"].([]int)
	versions := make([]int32, len(rawVersions))
	for i, v := range rawVersions {
		versions[i] = int32(v)
	}
	return &pb.GetTransitKeyResponse{
		Name:                 name,
		Type:                 keyType,
		CurrentVersion:       int32(currentVersion),
		MinDecryptionVersion: int32(minDecryptionVersion),
		AllowDeletion:        allowDeletion,
		Versions:             versions,
	}, nil
}

func (ts *transitServer) ListKeys(ctx context.Context, req *pb.ListTransitKeysRequest) (*pb.ListTransitKeysResponse, error) {
	if req.Mount == "" {
		return nil, status.Error(codes.InvalidArgument, "mount is required")
	}
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "list-keys", &engine.Request{
		Operation:  "list-keys",
		CallerInfo: ts.callerInfo(ctx),
	})
	if err != nil {
		return nil, err
	}
	keys := toStringSliceFromInterface(resp.Data["keys"])
	return &pb.ListTransitKeysResponse{Keys: keys}, nil
}

func (ts *transitServer) RotateKey(ctx context.Context, req *pb.RotateTransitKeyRequest) (*pb.RotateTransitKeyResponse, error) {
	if req.Mount == "" || req.Name == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and name are required")
	}
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "rotate-key", &engine.Request{
		Operation:  "rotate-key",
		CallerInfo: ts.callerInfo(ctx),
		Data:       map[string]interface{}{"name": req.Name},
	})
	if err != nil {
		return nil, err
	}
	name, _ := resp.Data["name"].(string)
	version, _ := resp.Data["version"].(int)
	ts.s.logger.Info("audit: transit key rotated", "mount", req.Mount, "key", name, "version", version, "username", callerUsername(ctx))
	return &pb.RotateTransitKeyResponse{Name: name, Version: int32(version)}, nil
}

func (ts *transitServer) UpdateKeyConfig(ctx context.Context, req *pb.UpdateTransitKeyConfigRequest) (*pb.UpdateTransitKeyConfigResponse, error) {
	if req.Mount == "" || req.Name == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and name are required")
	}
	data := map[string]interface{}{"name": req.Name}
	if req.MinDecryptionVersion != 0 {
		data["min_decryption_version"] = float64(req.MinDecryptionVersion)
	}
	data["allow_deletion"] = req.AllowDeletion

	_, err := ts.transitHandleRequest(ctx, req.Mount, "update-key-config", &engine.Request{
		Operation:  "update-key-config",
		CallerInfo: ts.callerInfo(ctx),
		Data:       data,
	})
	if err != nil {
		return nil, err
	}
	return &pb.UpdateTransitKeyConfigResponse{}, nil
}

func (ts *transitServer) TrimKey(ctx context.Context, req *pb.TrimTransitKeyRequest) (*pb.TrimTransitKeyResponse, error) {
	if req.Mount == "" || req.Name == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and name are required")
	}
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "trim-key", &engine.Request{
		Operation:  "trim-key",
		CallerInfo: ts.callerInfo(ctx),
		Data:       map[string]interface{}{"name": req.Name},
	})
	if err != nil {
		return nil, err
	}
	trimmed, _ := resp.Data["trimmed"].(int)
	return &pb.TrimTransitKeyResponse{Trimmed: int32(trimmed)}, nil
}

func (ts *transitServer) Encrypt(ctx context.Context, req *pb.TransitEncryptRequest) (*pb.TransitEncryptResponse, error) {
	if req.Mount == "" || req.Key == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and key are required")
	}
	data := map[string]interface{}{
		"key":       req.Key,
		"plaintext": req.Plaintext,
	}
	if req.Context != "" {
		data["context"] = req.Context
	}
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "encrypt", &engine.Request{
		Operation:   "encrypt",
		CallerInfo:  ts.callerInfo(ctx),
		CheckPolicy: ts.policyChecker(ctx),
		Data:        data,
	})
	if err != nil {
		return nil, err
	}
	ct, _ := resp.Data["ciphertext"].(string)
	return &pb.TransitEncryptResponse{Ciphertext: ct}, nil
}

func (ts *transitServer) Decrypt(ctx context.Context, req *pb.TransitDecryptRequest) (*pb.TransitDecryptResponse, error) {
	if req.Mount == "" || req.Key == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and key are required")
	}
	data := map[string]interface{}{
		"key":        req.Key,
		"ciphertext": req.Ciphertext,
	}
	if req.Context != "" {
		data["context"] = req.Context
	}
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "decrypt", &engine.Request{
		Operation:   "decrypt",
		CallerInfo:  ts.callerInfo(ctx),
		CheckPolicy: ts.policyChecker(ctx),
		Data:        data,
	})
	if err != nil {
		return nil, err
	}
	pt, _ := resp.Data["plaintext"].(string)
	return &pb.TransitDecryptResponse{Plaintext: pt}, nil
}

func (ts *transitServer) Rewrap(ctx context.Context, req *pb.TransitRewrapRequest) (*pb.TransitRewrapResponse, error) {
	if req.Mount == "" || req.Key == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and key are required")
	}
	data := map[string]interface{}{
		"key":        req.Key,
		"ciphertext": req.Ciphertext,
	}
	if req.Context != "" {
		data["context"] = req.Context
	}
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "rewrap", &engine.Request{
		Operation:   "rewrap",
		CallerInfo:  ts.callerInfo(ctx),
		CheckPolicy: ts.policyChecker(ctx),
		Data:        data,
	})
	if err != nil {
		return nil, err
	}
	ct, _ := resp.Data["ciphertext"].(string)
	return &pb.TransitRewrapResponse{Ciphertext: ct}, nil
}

func (ts *transitServer) BatchEncrypt(ctx context.Context, req *pb.TransitBatchEncryptRequest) (*pb.TransitBatchResponse, error) {
	if req.Mount == "" || req.Key == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and key are required")
	}
	items := protoItemsToInterface(req.Items)
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "batch-encrypt", &engine.Request{
		Operation:   "batch-encrypt",
		CallerInfo:  ts.callerInfo(ctx),
		CheckPolicy: ts.policyChecker(ctx),
		Data:        map[string]interface{}{"key": req.Key, "items": items},
	})
	if err != nil {
		return nil, err
	}
	return toBatchResponse(resp), nil
}

func (ts *transitServer) BatchDecrypt(ctx context.Context, req *pb.TransitBatchDecryptRequest) (*pb.TransitBatchResponse, error) {
	if req.Mount == "" || req.Key == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and key are required")
	}
	items := protoItemsToInterface(req.Items)
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "batch-decrypt", &engine.Request{
		Operation:   "batch-decrypt",
		CallerInfo:  ts.callerInfo(ctx),
		CheckPolicy: ts.policyChecker(ctx),
		Data:        map[string]interface{}{"key": req.Key, "items": items},
	})
	if err != nil {
		return nil, err
	}
	return toBatchResponse(resp), nil
}

func (ts *transitServer) BatchRewrap(ctx context.Context, req *pb.TransitBatchRewrapRequest) (*pb.TransitBatchResponse, error) {
	if req.Mount == "" || req.Key == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and key are required")
	}
	items := protoItemsToInterface(req.Items)
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "batch-rewrap", &engine.Request{
		Operation:   "batch-rewrap",
		CallerInfo:  ts.callerInfo(ctx),
		CheckPolicy: ts.policyChecker(ctx),
		Data:        map[string]interface{}{"key": req.Key, "items": items},
	})
	if err != nil {
		return nil, err
	}
	return toBatchResponse(resp), nil
}

func (ts *transitServer) Sign(ctx context.Context, req *pb.TransitSignRequest) (*pb.TransitSignResponse, error) {
	if req.Mount == "" || req.Key == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and key are required")
	}
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "sign", &engine.Request{
		Operation:   "sign",
		CallerInfo:  ts.callerInfo(ctx),
		CheckPolicy: ts.policyChecker(ctx),
		Data:        map[string]interface{}{"key": req.Key, "input": req.Input},
	})
	if err != nil {
		return nil, err
	}
	sig, _ := resp.Data["signature"].(string)
	return &pb.TransitSignResponse{Signature: sig}, nil
}

func (ts *transitServer) Verify(ctx context.Context, req *pb.TransitVerifyRequest) (*pb.TransitVerifyResponse, error) {
	if req.Mount == "" || req.Key == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and key are required")
	}
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "verify", &engine.Request{
		Operation:   "verify",
		CallerInfo:  ts.callerInfo(ctx),
		CheckPolicy: ts.policyChecker(ctx),
		Data: map[string]interface{}{
			"key":       req.Key,
			"input":     req.Input,
			"signature": req.Signature,
		},
	})
	if err != nil {
		return nil, err
	}
	valid, _ := resp.Data["valid"].(bool)
	return &pb.TransitVerifyResponse{Valid: valid}, nil
}

func (ts *transitServer) Hmac(ctx context.Context, req *pb.TransitHmacRequest) (*pb.TransitHmacResponse, error) {
	if req.Mount == "" || req.Key == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and key are required")
	}
	data := map[string]interface{}{
		"key":   req.Key,
		"input": req.Input,
	}
	if req.Hmac != "" {
		data["hmac"] = req.Hmac
	}
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "hmac", &engine.Request{
		Operation:   "hmac",
		CallerInfo:  ts.callerInfo(ctx),
		CheckPolicy: ts.policyChecker(ctx),
		Data:        data,
	})
	if err != nil {
		return nil, err
	}
	hmacStr, _ := resp.Data["hmac"].(string)
	valid, _ := resp.Data["valid"].(bool)
	return &pb.TransitHmacResponse{Hmac: hmacStr, Valid: valid}, nil
}

func (ts *transitServer) GetPublicKey(ctx context.Context, req *pb.GetTransitPublicKeyRequest) (*pb.GetTransitPublicKeyResponse, error) {
	if req.Mount == "" || req.Name == "" {
		return nil, status.Error(codes.InvalidArgument, "mount and name are required")
	}
	data := map[string]interface{}{"name": req.Name}
	if req.Version != 0 {
		data["version"] = float64(req.Version)
	}
	resp, err := ts.transitHandleRequest(ctx, req.Mount, "get-public-key", &engine.Request{
		Operation:  "get-public-key",
		CallerInfo: ts.callerInfo(ctx),
		Data:       data,
	})
	if err != nil {
		return nil, err
	}
	pk, _ := resp.Data["public_key"].(string)
	version, _ := resp.Data["version"].(int)
	keyType, _ := resp.Data["type"].(string)
	return &pb.GetTransitPublicKeyResponse{
		PublicKey: pk,
		Version:  int32(version),
		Type:     keyType,
	}, nil
}

// --- helpers ---

func protoItemsToInterface(items []*pb.TransitBatchItem) []interface{} {
	out := make([]interface{}, len(items))
	for i, item := range items {
		m := map[string]interface{}{}
		if item.Plaintext != "" {
			m["plaintext"] = item.Plaintext
		}
		if item.Ciphertext != "" {
			m["ciphertext"] = item.Ciphertext
		}
		if item.Context != "" {
			m["context"] = item.Context
		}
		if item.Reference != "" {
			m["reference"] = item.Reference
		}
		out[i] = m
	}
	return out
}

func toBatchResponse(resp *engine.Response) *pb.TransitBatchResponse {
	raw, _ := resp.Data["results"].([]interface{})
	results := make([]*pb.TransitBatchResultItem, 0, len(raw))
	for _, item := range raw {
		switch r := item.(type) {
		case map[string]interface{}:
			pt, _ := r["plaintext"].(string)
			ct, _ := r["ciphertext"].(string)
			ref, _ := r["reference"].(string)
			errStr, _ := r["error"].(string)
			results = append(results, &pb.TransitBatchResultItem{
				Plaintext:  pt,
				Ciphertext: ct,
				Reference:  ref,
				Error:      errStr,
			})
		}
	}
	return &pb.TransitBatchResponse{Results: results}
}